PostgreSQL Source Code  git master
lock.c File Reference
#include "postgres.h"
#include <signal.h>
#include <unistd.h>
#include "access/transam.h"
#include "access/twophase.h"
#include "access/twophase_rmgr.h"
#include "access/xact.h"
#include "access/xlog.h"
#include "access/xlogutils.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "pgstat.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "storage/sinvaladt.h"
#include "storage/spin.h"
#include "storage/standby.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
#include "utils/resowner_private.h"
Include dependency graph for lock.c:

Go to the source code of this file.

Data Structures

struct  TwoPhaseLockRecord
 
struct  FastPathStrongRelationLockData
 

Macros

#define NLOCKENTS()    mul_size(max_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
 
#define FAST_PATH_BITS_PER_SLOT   3
 
#define FAST_PATH_LOCKNUMBER_OFFSET   1
 
#define FAST_PATH_MASK   ((1 << FAST_PATH_BITS_PER_SLOT) - 1)
 
#define FAST_PATH_GET_BITS(proc, n)    (((proc)->fpLockBits >> (FAST_PATH_BITS_PER_SLOT * n)) & FAST_PATH_MASK)
 
#define FAST_PATH_BIT_POSITION(n, l)
 
#define FAST_PATH_SET_LOCKMODE(proc, n, l)    (proc)->fpLockBits |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)
 
#define FAST_PATH_CLEAR_LOCKMODE(proc, n, l)    (proc)->fpLockBits &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))
 
#define FAST_PATH_CHECK_LOCKMODE(proc, n, l)    ((proc)->fpLockBits & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))
 
#define EligibleForRelationFastPath(locktag, mode)
 
#define ConflictsWithRelationFastPath(locktag, mode)
 
#define FAST_PATH_STRONG_LOCK_HASH_BITS   10
 
#define FAST_PATH_STRONG_LOCK_HASH_PARTITIONS    (1 << FAST_PATH_STRONG_LOCK_HASH_BITS)
 
#define FastPathStrongLockHashPartition(hashcode)    ((hashcode) % FAST_PATH_STRONG_LOCK_HASH_PARTITIONS)
 
#define LOCK_PRINT(where, lock, type)   ((void) 0)
 
#define PROCLOCK_PRINT(where, proclockP)   ((void) 0)
 

Typedefs

typedef struct TwoPhaseLockRecord TwoPhaseLockRecord
 

Functions

static bool FastPathGrantRelationLock (Oid relid, LOCKMODE lockmode)
 
static bool FastPathUnGrantRelationLock (Oid relid, LOCKMODE lockmode)
 
static bool FastPathTransferRelationLocks (LockMethod lockMethodTable, const LOCKTAG *locktag, uint32 hashcode)
 
static PROCLOCKFastPathGetRelationLockEntry (LOCALLOCK *locallock)
 
static uint32 proclock_hash (const void *key, Size keysize)
 
static void RemoveLocalLock (LOCALLOCK *locallock)
 
static PROCLOCKSetupLockInTable (LockMethod lockMethodTable, PGPROC *proc, const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode)
 
static void GrantLockLocal (LOCALLOCK *locallock, ResourceOwner owner)
 
static void BeginStrongLockAcquire (LOCALLOCK *locallock, uint32 fasthashcode)
 
static void FinishStrongLockAcquire (void)
 
static void WaitOnLock (LOCALLOCK *locallock, ResourceOwner owner)
 
static void ReleaseLockIfHeld (LOCALLOCK *locallock, bool sessionLock)
 
static void LockReassignOwner (LOCALLOCK *locallock, ResourceOwner parent)
 
static bool UnGrantLock (LOCK *lock, LOCKMODE lockmode, PROCLOCK *proclock, LockMethod lockMethodTable)
 
static void CleanUpLock (LOCK *lock, PROCLOCK *proclock, LockMethod lockMethodTable, uint32 hashcode, bool wakeupNeeded)
 
static void LockRefindAndRelease (LockMethod lockMethodTable, PGPROC *proc, LOCKTAG *locktag, LOCKMODE lockmode, bool decrement_strong_lock_count)
 
static void GetSingleProcBlockerStatusData (PGPROC *blocked_proc, BlockedProcsData *data)
 
void InitLocks (void)
 
LockMethod GetLocksMethodTable (const LOCK *lock)
 
LockMethod GetLockTagsMethodTable (const LOCKTAG *locktag)
 
uint32 LockTagHashCode (const LOCKTAG *locktag)
 
static uint32 ProcLockHashCode (const PROCLOCKTAG *proclocktag, uint32 hashcode)
 
bool DoLockModesConflict (LOCKMODE mode1, LOCKMODE mode2)
 
bool LockHeldByMe (const LOCKTAG *locktag, LOCKMODE lockmode)
 
bool LockHasWaiters (const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
 
LockAcquireResult LockAcquire (const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait)
 
LockAcquireResult LockAcquireExtended (const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait, bool reportMemoryError, LOCALLOCK **locallockp)
 
static void CheckAndSetLockHeld (LOCALLOCK *locallock, bool acquired)
 
bool LockCheckConflicts (LockMethod lockMethodTable, LOCKMODE lockmode, LOCK *lock, PROCLOCK *proclock)
 
void GrantLock (LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
 
void AbortStrongLockAcquire (void)
 
void GrantAwaitedLock (void)
 
void MarkLockClear (LOCALLOCK *locallock)
 
void RemoveFromWaitQueue (PGPROC *proc, uint32 hashcode)
 
bool LockRelease (const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
 
void LockReleaseAll (LOCKMETHODID lockmethodid, bool allLocks)
 
void LockReleaseSession (LOCKMETHODID lockmethodid)
 
void LockReleaseCurrentOwner (LOCALLOCK **locallocks, int nlocks)
 
void LockReassignCurrentOwner (LOCALLOCK **locallocks, int nlocks)
 
VirtualTransactionIdGetLockConflicts (const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
 
static void CheckForSessionAndXactLocks (void)
 
void AtPrepare_Locks (void)
 
void PostPrepare_Locks (TransactionId xid)
 
Size LockShmemSize (void)
 
LockDataGetLockStatusData (void)
 
BlockedProcsDataGetBlockerStatusData (int blocked_pid)
 
xl_standby_lockGetRunningTransactionLocks (int *nlocks)
 
const char * GetLockmodeName (LOCKMETHODID lockmethodid, LOCKMODE mode)
 
void lock_twophase_recover (TransactionId xid, uint16 info, void *recdata, uint32 len)
 
void lock_twophase_standby_recover (TransactionId xid, uint16 info, void *recdata, uint32 len)
 
void lock_twophase_postcommit (TransactionId xid, uint16 info, void *recdata, uint32 len)
 
void lock_twophase_postabort (TransactionId xid, uint16 info, void *recdata, uint32 len)
 
void VirtualXactLockTableInsert (VirtualTransactionId vxid)
 
void VirtualXactLockTableCleanup (void)
 
static bool XactLockForVirtualXact (VirtualTransactionId vxid, TransactionId xid, bool wait)
 
bool VirtualXactLock (VirtualTransactionId vxid, bool wait)
 
int LockWaiterCount (const LOCKTAG *locktag)
 

Variables

int max_locks_per_xact
 
static const LOCKMASK LockConflicts []
 
static const char *const lock_mode_names []
 
static bool Dummy_trace = false
 
static const LockMethodData default_lockmethod
 
static const LockMethodData user_lockmethod
 
static const LockMethod LockMethods []
 
static int FastPathLocalUseCount = 0
 
static bool IsRelationExtensionLockHeld PG_USED_FOR_ASSERTS_ONLY = false
 
static volatile FastPathStrongRelationLockDataFastPathStrongRelationLocks
 
static HTABLockMethodLockHash
 
static HTABLockMethodProcLockHash
 
static HTABLockMethodLocalHash
 
static LOCALLOCKStrongLockInProgress
 
static LOCALLOCKawaitedLock
 
static ResourceOwner awaitedOwner
 

Macro Definition Documentation

◆ ConflictsWithRelationFastPath

#define ConflictsWithRelationFastPath (   locktag,
  mode 
)
Value:
((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
(locktag)->locktag_type == LOCKTAG_RELATION && \
(locktag)->locktag_field1 != InvalidOid && \
#define DEFAULT_LOCKMETHOD
Definition: lock.h:130
@ LOCKTAG_RELATION
Definition: lock.h:142
#define ShareUpdateExclusiveLock
Definition: lockdefs.h:39
static PgChecksumMode mode
Definition: pg_checksums.c:65
#define InvalidOid
Definition: postgres_ext.h:36

Definition at line 233 of file lock.c.

◆ EligibleForRelationFastPath

#define EligibleForRelationFastPath (   locktag,
  mode 
)
Value:
((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
(locktag)->locktag_type == LOCKTAG_RELATION && \
(locktag)->locktag_field1 == MyDatabaseId && \
Oid MyDatabaseId
Definition: globals.c:89

Definition at line 227 of file lock.c.

◆ FAST_PATH_BIT_POSITION

#define FAST_PATH_BIT_POSITION (   n,
 
)
Value:
AssertMacro((n) < FP_LOCK_SLOTS_PER_BACKEND), \
#define AssertMacro(condition)
Definition: c.h:816
#define FAST_PATH_LOCKNUMBER_OFFSET
Definition: lock.c:203
#define FAST_PATH_BITS_PER_SLOT
Definition: lock.c:202
#define FP_LOCK_SLOTS_PER_BACKEND
Definition: proc.h:77

Definition at line 207 of file lock.c.

◆ FAST_PATH_BITS_PER_SLOT

#define FAST_PATH_BITS_PER_SLOT   3

Definition at line 202 of file lock.c.

◆ FAST_PATH_CHECK_LOCKMODE

#define FAST_PATH_CHECK_LOCKMODE (   proc,
  n,
 
)     ((proc)->fpLockBits & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))

Definition at line 216 of file lock.c.

◆ FAST_PATH_CLEAR_LOCKMODE

#define FAST_PATH_CLEAR_LOCKMODE (   proc,
  n,
 
)     (proc)->fpLockBits &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))

Definition at line 214 of file lock.c.

◆ FAST_PATH_GET_BITS

#define FAST_PATH_GET_BITS (   proc,
 
)     (((proc)->fpLockBits >> (FAST_PATH_BITS_PER_SLOT * n)) & FAST_PATH_MASK)

Definition at line 205 of file lock.c.

◆ FAST_PATH_LOCKNUMBER_OFFSET

#define FAST_PATH_LOCKNUMBER_OFFSET   1

Definition at line 203 of file lock.c.

◆ FAST_PATH_MASK

#define FAST_PATH_MASK   ((1 << FAST_PATH_BITS_PER_SLOT) - 1)

Definition at line 204 of file lock.c.

◆ FAST_PATH_SET_LOCKMODE

#define FAST_PATH_SET_LOCKMODE (   proc,
  n,
 
)     (proc)->fpLockBits |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)

Definition at line 212 of file lock.c.

◆ FAST_PATH_STRONG_LOCK_HASH_BITS

#define FAST_PATH_STRONG_LOCK_HASH_BITS   10

Definition at line 260 of file lock.c.

◆ FAST_PATH_STRONG_LOCK_HASH_PARTITIONS

#define FAST_PATH_STRONG_LOCK_HASH_PARTITIONS    (1 << FAST_PATH_STRONG_LOCK_HASH_BITS)

Definition at line 261 of file lock.c.

◆ FastPathStrongLockHashPartition

#define FastPathStrongLockHashPartition (   hashcode)     ((hashcode) % FAST_PATH_STRONG_LOCK_HASH_PARTITIONS)

Definition at line 263 of file lock.c.

◆ LOCK_PRINT

#define LOCK_PRINT (   where,
  lock,
  type 
)    ((void) 0)

Definition at line 365 of file lock.c.

◆ NLOCKENTS

Definition at line 57 of file lock.c.

◆ PROCLOCK_PRINT

#define PROCLOCK_PRINT (   where,
  proclockP 
)    ((void) 0)

Definition at line 366 of file lock.c.

Typedef Documentation

◆ TwoPhaseLockRecord

Function Documentation

◆ AbortStrongLockAcquire()

void AbortStrongLockAcquire ( void  )

Definition at line 1757 of file lock.c.

1758 {
1759  uint32 fasthashcode;
1760  LOCALLOCK *locallock = StrongLockInProgress;
1761 
1762  if (locallock == NULL)
1763  return;
1764 
1765  fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
1766  Assert(locallock->holdsStrongLockCount == true);
1768  Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
1769  FastPathStrongRelationLocks->count[fasthashcode]--;
1770  locallock->holdsStrongLockCount = false;
1771  StrongLockInProgress = NULL;
1773 }
unsigned int uint32
Definition: c.h:452
Assert(fmt[strlen(fmt) - 1] !='\n')
#define FastPathStrongLockHashPartition(hashcode)
Definition: lock.c:263
static volatile FastPathStrongRelationLockData * FastPathStrongRelationLocks
Definition: lock.c:272
static LOCALLOCK * StrongLockInProgress
Definition: lock.c:287
#define SpinLockRelease(lock)
Definition: spin.h:64
#define SpinLockAcquire(lock)
Definition: spin.h:62
uint32 count[FAST_PATH_STRONG_LOCK_HASH_PARTITIONS]
Definition: lock.c:269
uint32 hashcode
Definition: lock.h:424
bool holdsStrongLockCount
Definition: lock.h:431

References Assert(), FastPathStrongRelationLockData::count, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, LOCALLOCK::hashcode, LOCALLOCK::holdsStrongLockCount, FastPathStrongRelationLockData::mutex, SpinLockAcquire, SpinLockRelease, and StrongLockInProgress.

Referenced by LockAcquireExtended(), and LockErrorCleanup().

◆ AtPrepare_Locks()

void AtPrepare_Locks ( void  )

Definition at line 3321 of file lock.c.

3322 {
3324  LOCALLOCK *locallock;
3325 
3326  /* First, verify there aren't locks of both xact and session level */
3328 
3329  /* Now do the per-locallock cleanup work */
3331 
3332  while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
3333  {
3334  TwoPhaseLockRecord record;
3335  LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
3336  bool haveSessionLock;
3337  bool haveXactLock;
3338  int i;
3339 
3340  /*
3341  * Ignore VXID locks. We don't want those to be held by prepared
3342  * transactions, since they aren't meaningful after a restart.
3343  */
3344  if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
3345  continue;
3346 
3347  /* Ignore it if we don't actually hold the lock */
3348  if (locallock->nLocks <= 0)
3349  continue;
3350 
3351  /* Scan to see whether we hold it at session or transaction level */
3352  haveSessionLock = haveXactLock = false;
3353  for (i = locallock->numLockOwners - 1; i >= 0; i--)
3354  {
3355  if (lockOwners[i].owner == NULL)
3356  haveSessionLock = true;
3357  else
3358  haveXactLock = true;
3359  }
3360 
3361  /* Ignore it if we have only session lock */
3362  if (!haveXactLock)
3363  continue;
3364 
3365  /* This can't happen, because we already checked it */
3366  if (haveSessionLock)
3367  ereport(ERROR,
3368  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
3369  errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
3370 
3371  /*
3372  * If the local lock was taken via the fast-path, we need to move it
3373  * to the primary lock table, or just get a pointer to the existing
3374  * primary lock table entry if by chance it's already been
3375  * transferred.
3376  */
3377  if (locallock->proclock == NULL)
3378  {
3379  locallock->proclock = FastPathGetRelationLockEntry(locallock);
3380  locallock->lock = locallock->proclock->tag.myLock;
3381  }
3382 
3383  /*
3384  * Arrange to not release any strong lock count held by this lock
3385  * entry. We must retain the count until the prepared transaction is
3386  * committed or rolled back.
3387  */
3388  locallock->holdsStrongLockCount = false;
3389 
3390  /*
3391  * Create a 2PC record.
3392  */
3393  memcpy(&(record.locktag), &(locallock->tag.lock), sizeof(LOCKTAG));
3394  record.lockmode = locallock->tag.mode;
3395 
3397  &record, sizeof(TwoPhaseLockRecord));
3398  }
3399 }
void * hash_seq_search(HASH_SEQ_STATUS *status)
Definition: dynahash.c:1436
void hash_seq_init(HASH_SEQ_STATUS *status, HTAB *hashp)
Definition: dynahash.c:1426
int errcode(int sqlerrcode)
Definition: elog.c:693
int errmsg(const char *fmt,...)
Definition: elog.c:904
#define ERROR
Definition: elog.h:33
#define ereport(elevel,...)
Definition: elog.h:143
int i
Definition: isn.c:73
static PROCLOCK * FastPathGetRelationLockEntry(LOCALLOCK *locallock)
Definition: lock.c:2810
static HTAB * LockMethodLocalHash
Definition: lock.c:283
static void CheckForSessionAndXactLocks(void)
Definition: lock.c:3233
@ LOCKTAG_VIRTUALTRANSACTION
Definition: lock.h:148
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:229
LOCKTAG lock
Definition: lock.h:402
LOCKMODE mode
Definition: lock.h:403
LOCALLOCKOWNER * lockOwners
Definition: lock.h:430
LOCK * lock
Definition: lock.h:425
int64 nLocks
Definition: lock.h:427
int numLockOwners
Definition: lock.h:428
PROCLOCK * proclock
Definition: lock.h:426
LOCALLOCKTAG tag
Definition: lock.h:421
Definition: lock.h:168
uint8 locktag_type
Definition: lock.h:173
LOCK * myLock
Definition: lock.h:357
PROCLOCKTAG tag
Definition: lock.h:364
LOCKTAG locktag
Definition: lock.c:161
LOCKMODE lockmode
Definition: lock.c:162
void RegisterTwoPhaseRecord(TwoPhaseRmgrId rmid, uint16 info, const void *data, uint32 len)
Definition: twophase.c:1259
#define TWOPHASE_RM_LOCK_ID
Definition: twophase_rmgr.h:25

References CheckForSessionAndXactLocks(), ereport, errcode(), errmsg(), ERROR, FastPathGetRelationLockEntry(), hash_seq_init(), hash_seq_search(), LOCALLOCK::holdsStrongLockCount, i, LOCALLOCKTAG::lock, LOCALLOCK::lock, LockMethodLocalHash, TwoPhaseLockRecord::lockmode, LOCALLOCK::lockOwners, TwoPhaseLockRecord::locktag, LOCKTAG::locktag_type, LOCKTAG_VIRTUALTRANSACTION, LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, LOCALLOCK::nLocks, LOCALLOCK::numLockOwners, LOCALLOCK::proclock, RegisterTwoPhaseRecord(), status(), PROCLOCK::tag, LOCALLOCK::tag, and TWOPHASE_RM_LOCK_ID.

Referenced by PrepareTransaction().

◆ BeginStrongLockAcquire()

static void BeginStrongLockAcquire ( LOCALLOCK locallock,
uint32  fasthashcode 
)
static

Definition at line 1721 of file lock.c.

1722 {
1723  Assert(StrongLockInProgress == NULL);
1724  Assert(locallock->holdsStrongLockCount == false);
1725 
1726  /*
1727  * Adding to a memory location is not atomic, so we take a spinlock to
1728  * ensure we don't collide with someone else trying to bump the count at
1729  * the same time.
1730  *
1731  * XXX: It might be worth considering using an atomic fetch-and-add
1732  * instruction here, on architectures where that is supported.
1733  */
1734 
1736  FastPathStrongRelationLocks->count[fasthashcode]++;
1737  locallock->holdsStrongLockCount = true;
1738  StrongLockInProgress = locallock;
1740 }

References Assert(), FastPathStrongRelationLockData::count, FastPathStrongRelationLocks, LOCALLOCK::holdsStrongLockCount, FastPathStrongRelationLockData::mutex, SpinLockAcquire, SpinLockRelease, and StrongLockInProgress.

Referenced by LockAcquireExtended().

◆ CheckAndSetLockHeld()

static void CheckAndSetLockHeld ( LOCALLOCK locallock,
bool  acquired 
)
inlinestatic

Definition at line 1352 of file lock.c.

1353 {
1354 #ifdef USE_ASSERT_CHECKING
1355  if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_RELATION_EXTEND)
1356  IsRelationExtensionLockHeld = acquired;
1357  else if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_PAGE)
1358  IsPageLockHeld = acquired;
1359 
1360 #endif
1361 }
@ LOCKTAG_RELATION_EXTEND
Definition: lock.h:143
@ LOCKTAG_PAGE
Definition: lock.h:145
#define LOCALLOCK_LOCKTAG(llock)
Definition: lock.h:436

References LOCALLOCK_LOCKTAG, LOCKTAG_PAGE, and LOCKTAG_RELATION_EXTEND.

Referenced by GrantLockLocal(), and RemoveLocalLock().

◆ CheckForSessionAndXactLocks()

static void CheckForSessionAndXactLocks ( void  )
static

Definition at line 3233 of file lock.c.

3234 {
3235  typedef struct
3236  {
3237  LOCKTAG lock; /* identifies the lockable object */
3238  bool sessLock; /* is any lockmode held at session level? */
3239  bool xactLock; /* is any lockmode held at xact level? */
3240  } PerLockTagEntry;
3241 
3242  HASHCTL hash_ctl;
3243  HTAB *lockhtab;
3245  LOCALLOCK *locallock;
3246 
3247  /* Create a local hash table keyed by LOCKTAG only */
3248  hash_ctl.keysize = sizeof(LOCKTAG);
3249  hash_ctl.entrysize = sizeof(PerLockTagEntry);
3250  hash_ctl.hcxt = CurrentMemoryContext;
3251 
3252  lockhtab = hash_create("CheckForSessionAndXactLocks table",
3253  256, /* arbitrary initial size */
3254  &hash_ctl,
3256 
3257  /* Scan local lock table to find entries for each LOCKTAG */
3259 
3260  while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
3261  {
3262  LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
3263  PerLockTagEntry *hentry;
3264  bool found;
3265  int i;
3266 
3267  /*
3268  * Ignore VXID locks. We don't want those to be held by prepared
3269  * transactions, since they aren't meaningful after a restart.
3270  */
3271  if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
3272  continue;
3273 
3274  /* Ignore it if we don't actually hold the lock */
3275  if (locallock->nLocks <= 0)
3276  continue;
3277 
3278  /* Otherwise, find or make an entry in lockhtab */
3279  hentry = (PerLockTagEntry *) hash_search(lockhtab,
3280  (void *) &locallock->tag.lock,
3281  HASH_ENTER, &found);
3282  if (!found) /* initialize, if newly created */
3283  hentry->sessLock = hentry->xactLock = false;
3284 
3285  /* Scan to see if we hold lock at session or xact level or both */
3286  for (i = locallock->numLockOwners - 1; i >= 0; i--)
3287  {
3288  if (lockOwners[i].owner == NULL)
3289  hentry->sessLock = true;
3290  else
3291  hentry->xactLock = true;
3292  }
3293 
3294  /*
3295  * We can throw error immediately when we see both types of locks; no
3296  * need to wait around to see if there are more violations.
3297  */
3298  if (hentry->sessLock && hentry->xactLock)
3299  ereport(ERROR,
3300  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
3301  errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
3302  }
3303 
3304  /* Success, so clean up */
3305  hash_destroy(lockhtab);
3306 }
void hash_destroy(HTAB *hashp)
Definition: dynahash.c:862
void * hash_search(HTAB *hashp, const void *keyPtr, HASHACTION action, bool *foundPtr)
Definition: dynahash.c:954
HTAB * hash_create(const char *tabname, long nelem, const HASHCTL *info, int flags)
Definition: dynahash.c:349
@ HASH_ENTER
Definition: hsearch.h:114
#define HASH_CONTEXT
Definition: hsearch.h:102
#define HASH_ELEM
Definition: hsearch.h:95
#define HASH_BLOBS
Definition: hsearch.h:97
struct LOCKTAG LOCKTAG
MemoryContext CurrentMemoryContext
Definition: mcxt.c:42
Size keysize
Definition: hsearch.h:75
Size entrysize
Definition: hsearch.h:76
MemoryContext hcxt
Definition: hsearch.h:86
Definition: dynahash.c:220

References CurrentMemoryContext, HASHCTL::entrysize, ereport, errcode(), errmsg(), ERROR, HASH_BLOBS, HASH_CONTEXT, hash_create(), hash_destroy(), HASH_ELEM, HASH_ENTER, hash_search(), hash_seq_init(), hash_seq_search(), HASHCTL::hcxt, i, HASHCTL::keysize, LOCALLOCKTAG::lock, LockMethodLocalHash, LOCALLOCK::lockOwners, LOCKTAG::locktag_type, LOCKTAG_VIRTUALTRANSACTION, LOCALLOCK::nLocks, LOCALLOCK::numLockOwners, status(), and LOCALLOCK::tag.

Referenced by AtPrepare_Locks().

◆ CleanUpLock()

static void CleanUpLock ( LOCK lock,
PROCLOCK proclock,
LockMethod  lockMethodTable,
uint32  hashcode,
bool  wakeupNeeded 
)
static

Definition at line 1635 of file lock.c.

1638 {
1639  /*
1640  * If this was my last hold on this lock, delete my entry in the proclock
1641  * table.
1642  */
1643  if (proclock->holdMask == 0)
1644  {
1645  uint32 proclock_hashcode;
1646 
1647  PROCLOCK_PRINT("CleanUpLock: deleting", proclock);
1648  SHMQueueDelete(&proclock->lockLink);
1649  SHMQueueDelete(&proclock->procLink);
1650  proclock_hashcode = ProcLockHashCode(&proclock->tag, hashcode);
1652  (void *) &(proclock->tag),
1653  proclock_hashcode,
1654  HASH_REMOVE,
1655  NULL))
1656  elog(PANIC, "proclock table corrupted");
1657  }
1658 
1659  if (lock->nRequested == 0)
1660  {
1661  /*
1662  * The caller just released the last lock, so garbage-collect the lock
1663  * object.
1664  */
1665  LOCK_PRINT("CleanUpLock: deleting", lock, 0);
1666  Assert(SHMQueueEmpty(&(lock->procLocks)));
1668  (void *) &(lock->tag),
1669  hashcode,
1670  HASH_REMOVE,
1671  NULL))
1672  elog(PANIC, "lock table corrupted");
1673  }
1674  else if (wakeupNeeded)
1675  {
1676  /* There are waiters on this lock, so wake them up. */
1677  ProcLockWakeup(lockMethodTable, lock);
1678  }
1679 }
void * hash_search_with_hash_value(HTAB *hashp, const void *keyPtr, uint32 hashvalue, HASHACTION action, bool *foundPtr)
Definition: dynahash.c:967
#define PANIC
Definition: elog.h:36
#define elog(elevel,...)
Definition: elog.h:218
@ HASH_REMOVE
Definition: hsearch.h:115
#define LOCK_PRINT(where, lock, type)
Definition: lock.c:365
static uint32 ProcLockHashCode(const PROCLOCKTAG *proclocktag, uint32 hashcode)
Definition: lock.c:565
#define PROCLOCK_PRINT(where, proclockP)
Definition: lock.c:366
static HTAB * LockMethodLockHash
Definition: lock.c:281
static HTAB * LockMethodProcLockHash
Definition: lock.c:282
void SHMQueueDelete(SHM_QUEUE *queue)
Definition: shmqueue.c:68
bool SHMQueueEmpty(const SHM_QUEUE *queue)
Definition: shmqueue.c:180
void ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock)
Definition: proc.c:1702
int nRequested
Definition: lock.h:311
LOCKTAG tag
Definition: lock.h:303
SHM_QUEUE procLocks
Definition: lock.h:308
LOCKMASK holdMask
Definition: lock.h:368
SHM_QUEUE lockLink
Definition: lock.h:370
SHM_QUEUE procLink
Definition: lock.h:371

References Assert(), elog, HASH_REMOVE, hash_search_with_hash_value(), PROCLOCK::holdMask, LOCK_PRINT, PROCLOCK::lockLink, LockMethodLockHash, LockMethodProcLockHash, LOCK::nRequested, PANIC, PROCLOCK::procLink, PROCLOCK_PRINT, ProcLockHashCode(), LOCK::procLocks, ProcLockWakeup(), SHMQueueDelete(), SHMQueueEmpty(), LOCK::tag, and PROCLOCK::tag.

Referenced by LockRefindAndRelease(), LockRelease(), LockReleaseAll(), and RemoveFromWaitQueue().

◆ DoLockModesConflict()

bool DoLockModesConflict ( LOCKMODE  mode1,
LOCKMODE  mode2 
)

Definition at line 583 of file lock.c.

584 {
585  LockMethod lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
586 
587  if (lockMethodTable->conflictTab[mode1] & LOCKBIT_ON(mode2))
588  return true;
589 
590  return false;
591 }
static const LockMethod LockMethods[]
Definition: lock.c:151
#define LOCKBIT_ON(lockmode)
Definition: lock.h:89
const LOCKMASK * conflictTab
Definition: lock.h:116

References LockMethodData::conflictTab, DEFAULT_LOCKMETHOD, LOCKBIT_ON, and LockMethods.

Referenced by Do_MultiXactIdWait(), DoesMultiXactIdConflict(), initialize_reloptions(), and test_lockmode_for_conflict().

◆ FastPathGetRelationLockEntry()

static PROCLOCK * FastPathGetRelationLockEntry ( LOCALLOCK locallock)
static

Definition at line 2810 of file lock.c.

2811 {
2812  LockMethod lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
2813  LOCKTAG *locktag = &locallock->tag.lock;
2814  PROCLOCK *proclock = NULL;
2815  LWLock *partitionLock = LockHashPartitionLock(locallock->hashcode);
2816  Oid relid = locktag->locktag_field2;
2817  uint32 f;
2818 
2820 
2821  for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
2822  {
2823  uint32 lockmode;
2824 
2825  /* Look for an allocated slot matching the given relid. */
2826  if (relid != MyProc->fpRelId[f] || FAST_PATH_GET_BITS(MyProc, f) == 0)
2827  continue;
2828 
2829  /* If we don't have a lock of the given mode, forget it! */
2830  lockmode = locallock->tag.mode;
2831  if (!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
2832  break;
2833 
2834  /* Find or create lock object. */
2835  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
2836 
2837  proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
2838  locallock->hashcode, lockmode);
2839  if (!proclock)
2840  {
2841  LWLockRelease(partitionLock);
2843  ereport(ERROR,
2844  (errcode(ERRCODE_OUT_OF_MEMORY),
2845  errmsg("out of shared memory"),
2846  errhint("You might need to increase max_locks_per_transaction.")));
2847  }
2848  GrantLock(proclock->tag.myLock, proclock, lockmode);
2849  FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
2850 
2851  LWLockRelease(partitionLock);
2852 
2853  /* No need to examine remaining slots. */
2854  break;
2855  }
2856 
2858 
2859  /* Lock may have already been transferred by some other backend. */
2860  if (proclock == NULL)
2861  {
2862  LOCK *lock;
2863  PROCLOCKTAG proclocktag;
2864  uint32 proclock_hashcode;
2865 
2866  LWLockAcquire(partitionLock, LW_SHARED);
2867 
2869  (void *) locktag,
2870  locallock->hashcode,
2871  HASH_FIND,
2872  NULL);
2873  if (!lock)
2874  elog(ERROR, "failed to re-find shared lock object");
2875 
2876  proclocktag.myLock = lock;
2877  proclocktag.myProc = MyProc;
2878 
2879  proclock_hashcode = ProcLockHashCode(&proclocktag, locallock->hashcode);
2880  proclock = (PROCLOCK *)
2882  (void *) &proclocktag,
2883  proclock_hashcode,
2884  HASH_FIND,
2885  NULL);
2886  if (!proclock)
2887  elog(ERROR, "failed to re-find shared proclock object");
2888  LWLockRelease(partitionLock);
2889  }
2890 
2891  return proclock;
2892 }
int errhint(const char *fmt,...)
Definition: elog.c:1151
@ HASH_FIND
Definition: hsearch.h:113
static PROCLOCK * SetupLockInTable(LockMethod lockMethodTable, PGPROC *proc, const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode)
Definition: lock.c:1170
#define FAST_PATH_CHECK_LOCKMODE(proc, n, l)
Definition: lock.c:216
void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
Definition: lock.c:1555
#define FAST_PATH_CLEAR_LOCKMODE(proc, n, l)
Definition: lock.c:214
#define FAST_PATH_GET_BITS(proc, n)
Definition: lock.c:205
#define LockHashPartitionLock(hashcode)
Definition: lock.h:519
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1196
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1800
@ LW_SHARED
Definition: lwlock.h:105
@ LW_EXCLUSIVE
Definition: lwlock.h:104
unsigned int Oid
Definition: postgres_ext.h:31
PGPROC * MyProc
Definition: proc.c:68
uint32 locktag_field2
Definition: lock.h:170
Definition: lock.h:301
Definition: lwlock.h:32
LWLock fpInfoLock
Definition: proc.h:278
Oid fpRelId[FP_LOCK_SLOTS_PER_BACKEND]
Definition: proc.h:280
PGPROC * myProc
Definition: lock.h:358
Definition: lock.h:362

References DEFAULT_LOCKMETHOD, elog, ereport, errcode(), errhint(), errmsg(), ERROR, FAST_PATH_CHECK_LOCKMODE, FAST_PATH_CLEAR_LOCKMODE, FAST_PATH_GET_BITS, FP_LOCK_SLOTS_PER_BACKEND, PGPROC::fpInfoLock, PGPROC::fpRelId, GrantLock(), HASH_FIND, hash_search_with_hash_value(), LOCALLOCK::hashcode, LOCALLOCKTAG::lock, LockHashPartitionLock, LockMethodLockHash, LockMethodProcLockHash, LockMethods, LOCKTAG::locktag_field2, LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, PROCLOCKTAG::myProc, ProcLockHashCode(), SetupLockInTable(), PROCLOCK::tag, and LOCALLOCK::tag.

Referenced by AtPrepare_Locks().

◆ FastPathGrantRelationLock()

static bool FastPathGrantRelationLock ( Oid  relid,
LOCKMODE  lockmode 
)
static

Definition at line 2655 of file lock.c.

2656 {
2657  uint32 f;
2658  uint32 unused_slot = FP_LOCK_SLOTS_PER_BACKEND;
2659 
2660  /* Scan for existing entry for this relid, remembering empty slot. */
2661  for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
2662  {
2663  if (FAST_PATH_GET_BITS(MyProc, f) == 0)
2664  unused_slot = f;
2665  else if (MyProc->fpRelId[f] == relid)
2666  {
2667  Assert(!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode));
2668  FAST_PATH_SET_LOCKMODE(MyProc, f, lockmode);
2669  return true;
2670  }
2671  }
2672 
2673  /* If no existing entry, use any empty slot. */
2674  if (unused_slot < FP_LOCK_SLOTS_PER_BACKEND)
2675  {
2676  MyProc->fpRelId[unused_slot] = relid;
2677  FAST_PATH_SET_LOCKMODE(MyProc, unused_slot, lockmode);
2679  return true;
2680  }
2681 
2682  /* No existing entry, and no empty slot. */
2683  return false;
2684 }
#define FAST_PATH_SET_LOCKMODE(proc, n, l)
Definition: lock.c:212
static int FastPathLocalUseCount
Definition: lock.c:172

References Assert(), FAST_PATH_CHECK_LOCKMODE, FAST_PATH_GET_BITS, FAST_PATH_SET_LOCKMODE, FastPathLocalUseCount, FP_LOCK_SLOTS_PER_BACKEND, PGPROC::fpRelId, and MyProc.

Referenced by LockAcquireExtended().

◆ FastPathTransferRelationLocks()

static bool FastPathTransferRelationLocks ( LockMethod  lockMethodTable,
const LOCKTAG locktag,
uint32  hashcode 
)
static

Definition at line 2722 of file lock.c.

2724 {
2725  LWLock *partitionLock = LockHashPartitionLock(hashcode);
2726  Oid relid = locktag->locktag_field2;
2727  uint32 i;
2728 
2729  /*
2730  * Every PGPROC that can potentially hold a fast-path lock is present in
2731  * ProcGlobal->allProcs. Prepared transactions are not, but any
2732  * outstanding fast-path locks held by prepared transactions are
2733  * transferred to the main lock table.
2734  */
2735  for (i = 0; i < ProcGlobal->allProcCount; i++)
2736  {
2737  PGPROC *proc = &ProcGlobal->allProcs[i];
2738  uint32 f;
2739 
2741 
2742  /*
2743  * If the target backend isn't referencing the same database as the
2744  * lock, then we needn't examine the individual relation IDs at all;
2745  * none of them can be relevant.
2746  *
2747  * proc->databaseId is set at backend startup time and never changes
2748  * thereafter, so it might be safe to perform this test before
2749  * acquiring &proc->fpInfoLock. In particular, it's certainly safe to
2750  * assume that if the target backend holds any fast-path locks, it
2751  * must have performed a memory-fencing operation (in particular, an
2752  * LWLock acquisition) since setting proc->databaseId. However, it's
2753  * less clear that our backend is certain to have performed a memory
2754  * fencing operation since the other backend set proc->databaseId. So
2755  * for now, we test it after acquiring the LWLock just to be safe.
2756  */
2757  if (proc->databaseId != locktag->locktag_field1)
2758  {
2759  LWLockRelease(&proc->fpInfoLock);
2760  continue;
2761  }
2762 
2763  for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
2764  {
2765  uint32 lockmode;
2766 
2767  /* Look for an allocated slot matching the given relid. */
2768  if (relid != proc->fpRelId[f] || FAST_PATH_GET_BITS(proc, f) == 0)
2769  continue;
2770 
2771  /* Find or create lock object. */
2772  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
2773  for (lockmode = FAST_PATH_LOCKNUMBER_OFFSET;
2775  ++lockmode)
2776  {
2777  PROCLOCK *proclock;
2778 
2779  if (!FAST_PATH_CHECK_LOCKMODE(proc, f, lockmode))
2780  continue;
2781  proclock = SetupLockInTable(lockMethodTable, proc, locktag,
2782  hashcode, lockmode);
2783  if (!proclock)
2784  {
2785  LWLockRelease(partitionLock);
2786  LWLockRelease(&proc->fpInfoLock);
2787  return false;
2788  }
2789  GrantLock(proclock->tag.myLock, proclock, lockmode);
2790  FAST_PATH_CLEAR_LOCKMODE(proc, f, lockmode);
2791  }
2792  LWLockRelease(partitionLock);
2793 
2794  /* No need to examine remaining slots. */
2795  break;
2796  }
2797  LWLockRelease(&proc->fpInfoLock);
2798  }
2799  return true;
2800 }
PROC_HDR * ProcGlobal
Definition: proc.c:80
uint32 locktag_field1
Definition: lock.h:169
Definition: proc.h:160
Oid databaseId
Definition: proc.h:192
PGPROC * allProcs
Definition: proc.h:356
uint32 allProcCount
Definition: proc.h:374

References PROC_HDR::allProcCount, PROC_HDR::allProcs, PGPROC::databaseId, FAST_PATH_BITS_PER_SLOT, FAST_PATH_CHECK_LOCKMODE, FAST_PATH_CLEAR_LOCKMODE, FAST_PATH_GET_BITS, FAST_PATH_LOCKNUMBER_OFFSET, FP_LOCK_SLOTS_PER_BACKEND, PGPROC::fpInfoLock, PGPROC::fpRelId, GrantLock(), i, LockHashPartitionLock, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), PROCLOCKTAG::myLock, ProcGlobal, SetupLockInTable(), and PROCLOCK::tag.

Referenced by LockAcquireExtended().

◆ FastPathUnGrantRelationLock()

static bool FastPathUnGrantRelationLock ( Oid  relid,
LOCKMODE  lockmode 
)
static

Definition at line 2692 of file lock.c.

2693 {
2694  uint32 f;
2695  bool result = false;
2696 
2698  for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
2699  {
2700  if (MyProc->fpRelId[f] == relid
2701  && FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
2702  {
2703  Assert(!result);
2704  FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
2705  result = true;
2706  /* we continue iterating so as to update FastPathLocalUseCount */
2707  }
2708  if (FAST_PATH_GET_BITS(MyProc, f) != 0)
2710  }
2711  return result;
2712 }

References Assert(), FAST_PATH_CHECK_LOCKMODE, FAST_PATH_CLEAR_LOCKMODE, FAST_PATH_GET_BITS, FastPathLocalUseCount, FP_LOCK_SLOTS_PER_BACKEND, PGPROC::fpRelId, and MyProc.

Referenced by LockRelease(), and LockReleaseAll().

◆ FinishStrongLockAcquire()

static void FinishStrongLockAcquire ( void  )
static

Definition at line 1747 of file lock.c.

1748 {
1749  StrongLockInProgress = NULL;
1750 }

References StrongLockInProgress.

Referenced by LockAcquireExtended().

◆ GetBlockerStatusData()

BlockedProcsData* GetBlockerStatusData ( int  blocked_pid)

Definition at line 3838 of file lock.c.

3839 {
3841  PGPROC *proc;
3842  int i;
3843 
3845 
3846  /*
3847  * Guess how much space we'll need, and preallocate. Most of the time
3848  * this will avoid needing to do repalloc while holding the LWLocks. (We
3849  * assume, but check with an Assert, that MaxBackends is enough entries
3850  * for the procs[] array; the other two could need enlargement, though.)
3851  */
3852  data->nprocs = data->nlocks = data->npids = 0;
3853  data->maxprocs = data->maxlocks = data->maxpids = MaxBackends;
3854  data->procs = (BlockedProcData *) palloc(sizeof(BlockedProcData) * data->maxprocs);
3855  data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * data->maxlocks);
3856  data->waiter_pids = (int *) palloc(sizeof(int) * data->maxpids);
3857 
3858  /*
3859  * In order to search the ProcArray for blocked_pid and assume that that
3860  * entry won't immediately disappear under us, we must hold ProcArrayLock.
3861  * In addition, to examine the lock grouping fields of any other backend,
3862  * we must hold all the hash partition locks. (Only one of those locks is
3863  * actually relevant for any one lock group, but we can't know which one
3864  * ahead of time.) It's fairly annoying to hold all those locks
3865  * throughout this, but it's no worse than GetLockStatusData(), and it
3866  * does have the advantage that we're guaranteed to return a
3867  * self-consistent instantaneous state.
3868  */
3869  LWLockAcquire(ProcArrayLock, LW_SHARED);
3870 
3871  proc = BackendPidGetProcWithLock(blocked_pid);
3872 
3873  /* Nothing to do if it's gone */
3874  if (proc != NULL)
3875  {
3876  /*
3877  * Acquire lock on the entire shared lock data structure. See notes
3878  * in GetLockStatusData().
3879  */
3880  for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
3882 
3883  if (proc->lockGroupLeader == NULL)
3884  {
3885  /* Easy case, proc is not a lock group member */
3887  }
3888  else
3889  {
3890  /* Examine all procs in proc's lock group */
3891  dlist_iter iter;
3892 
3894  {
3895  PGPROC *memberProc;
3896 
3897  memberProc = dlist_container(PGPROC, lockGroupLink, iter.cur);
3898  GetSingleProcBlockerStatusData(memberProc, data);
3899  }
3900  }
3901 
3902  /*
3903  * And release locks. See notes in GetLockStatusData().
3904  */
3905  for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
3907 
3908  Assert(data->nprocs <= data->maxprocs);
3909  }
3910 
3911  LWLockRelease(ProcArrayLock);
3912 
3913  return data;
3914 }
int MaxBackends
Definition: globals.c:140
#define dlist_foreach(iter, lhead)
Definition: ilist.h:526
#define dlist_container(type, membername, ptr)
Definition: ilist.h:496
static void GetSingleProcBlockerStatusData(PGPROC *blocked_proc, BlockedProcsData *data)
Definition: lock.c:3918
#define LockHashPartitionLockByIndex(i)
Definition: lock.h:522
#define NUM_LOCK_PARTITIONS
Definition: lwlock.h:87
void * palloc(Size size)
Definition: mcxt.c:1068
const void * data
PGPROC * BackendPidGetProcWithLock(int pid)
Definition: procarray.c:3178
dlist_head lockGroupMembers
Definition: proc.h:290
PGPROC * lockGroupLeader
Definition: proc.h:289
dlist_node * cur
Definition: ilist.h:161

References Assert(), BackendPidGetProcWithLock(), dlist_iter::cur, data, dlist_container, dlist_foreach, GetSingleProcBlockerStatusData(), i, PGPROC::lockGroupLeader, PGPROC::lockGroupMembers, LockHashPartitionLockByIndex, LW_SHARED, LWLockAcquire(), LWLockRelease(), MaxBackends, NUM_LOCK_PARTITIONS, and palloc().

Referenced by pg_blocking_pids().

◆ GetLockConflicts()

VirtualTransactionId* GetLockConflicts ( const LOCKTAG locktag,
LOCKMODE  lockmode,
int *  countp 
)

Definition at line 2914 of file lock.c.

2915 {
2916  static VirtualTransactionId *vxids;
2917  LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
2918  LockMethod lockMethodTable;
2919  LOCK *lock;
2920  LOCKMASK conflictMask;
2921  SHM_QUEUE *procLocks;
2922  PROCLOCK *proclock;
2923  uint32 hashcode;
2924  LWLock *partitionLock;
2925  int count = 0;
2926  int fast_count = 0;
2927 
2928  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
2929  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
2930  lockMethodTable = LockMethods[lockmethodid];
2931  if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
2932  elog(ERROR, "unrecognized lock mode: %d", lockmode);
2933 
2934  /*
2935  * Allocate memory to store results, and fill with InvalidVXID. We only
2936  * need enough space for MaxBackends + max_prepared_xacts + a terminator.
2937  * InHotStandby allocate once in TopMemoryContext.
2938  */
2939  if (InHotStandby)
2940  {
2941  if (vxids == NULL)
2942  vxids = (VirtualTransactionId *)
2944  sizeof(VirtualTransactionId) *
2946  }
2947  else
2948  vxids = (VirtualTransactionId *)
2949  palloc0(sizeof(VirtualTransactionId) *
2951 
2952  /* Compute hash code and partition lock, and look up conflicting modes. */
2953  hashcode = LockTagHashCode(locktag);
2954  partitionLock = LockHashPartitionLock(hashcode);
2955  conflictMask = lockMethodTable->conflictTab[lockmode];
2956 
2957  /*
2958  * Fast path locks might not have been entered in the primary lock table.
2959  * If the lock we're dealing with could conflict with such a lock, we must
2960  * examine each backend's fast-path array for conflicts.
2961  */
2962  if (ConflictsWithRelationFastPath(locktag, lockmode))
2963  {
2964  int i;
2965  Oid relid = locktag->locktag_field2;
2966  VirtualTransactionId vxid;
2967 
2968  /*
2969  * Iterate over relevant PGPROCs. Anything held by a prepared
2970  * transaction will have been transferred to the primary lock table,
2971  * so we need not worry about those. This is all a bit fuzzy, because
2972  * new locks could be taken after we've visited a particular
2973  * partition, but the callers had better be prepared to deal with that
2974  * anyway, since the locks could equally well be taken between the
2975  * time we return the value and the time the caller does something
2976  * with it.
2977  */
2978  for (i = 0; i < ProcGlobal->allProcCount; i++)
2979  {
2980  PGPROC *proc = &ProcGlobal->allProcs[i];
2981  uint32 f;
2982 
2983  /* A backend never blocks itself */
2984  if (proc == MyProc)
2985  continue;
2986 
2988 
2989  /*
2990  * If the target backend isn't referencing the same database as
2991  * the lock, then we needn't examine the individual relation IDs
2992  * at all; none of them can be relevant.
2993  *
2994  * See FastPathTransferRelationLocks() for discussion of why we do
2995  * this test after acquiring the lock.
2996  */
2997  if (proc->databaseId != locktag->locktag_field1)
2998  {
2999  LWLockRelease(&proc->fpInfoLock);
3000  continue;
3001  }
3002 
3003  for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
3004  {
3005  uint32 lockmask;
3006 
3007  /* Look for an allocated slot matching the given relid. */
3008  if (relid != proc->fpRelId[f])
3009  continue;
3010  lockmask = FAST_PATH_GET_BITS(proc, f);
3011  if (!lockmask)
3012  continue;
3013  lockmask <<= FAST_PATH_LOCKNUMBER_OFFSET;
3014 
3015  /*
3016  * There can only be one entry per relation, so if we found it
3017  * and it doesn't conflict, we can skip the rest of the slots.
3018  */
3019  if ((lockmask & conflictMask) == 0)
3020  break;
3021 
3022  /* Conflict! */
3023  GET_VXID_FROM_PGPROC(vxid, *proc);
3024 
3025  if (VirtualTransactionIdIsValid(vxid))
3026  vxids[count++] = vxid;
3027  /* else, xact already committed or aborted */
3028 
3029  /* No need to examine remaining slots. */
3030  break;
3031  }
3032 
3033  LWLockRelease(&proc->fpInfoLock);
3034  }
3035  }
3036 
3037  /* Remember how many fast-path conflicts we found. */
3038  fast_count = count;
3039 
3040  /*
3041  * Look up the lock object matching the tag.
3042  */
3043  LWLockAcquire(partitionLock, LW_SHARED);
3044 
3046  (const void *) locktag,
3047  hashcode,
3048  HASH_FIND,
3049  NULL);
3050  if (!lock)
3051  {
3052  /*
3053  * If the lock object doesn't exist, there is nothing holding a lock
3054  * on this lockable object.
3055  */
3056  LWLockRelease(partitionLock);
3057  vxids[count].backendId = InvalidBackendId;
3059  if (countp)
3060  *countp = count;
3061  return vxids;
3062  }
3063 
3064  /*
3065  * Examine each existing holder (or awaiter) of the lock.
3066  */
3067 
3068  procLocks = &(lock->procLocks);
3069 
3070  proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
3071  offsetof(PROCLOCK, lockLink));
3072 
3073  while (proclock)
3074  {
3075  if (conflictMask & proclock->holdMask)
3076  {
3077  PGPROC *proc = proclock->tag.myProc;
3078 
3079  /* A backend never blocks itself */
3080  if (proc != MyProc)
3081  {
3082  VirtualTransactionId vxid;
3083 
3084  GET_VXID_FROM_PGPROC(vxid, *proc);
3085 
3086  if (VirtualTransactionIdIsValid(vxid))
3087  {
3088  int i;
3089 
3090  /* Avoid duplicate entries. */
3091  for (i = 0; i < fast_count; ++i)
3092  if (VirtualTransactionIdEquals(vxids[i], vxid))
3093  break;
3094  if (i >= fast_count)
3095  vxids[count++] = vxid;
3096  }
3097  /* else, xact already committed or aborted */
3098  }
3099  }
3100 
3101  proclock = (PROCLOCK *) SHMQueueNext(procLocks, &proclock->lockLink,
3102  offsetof(PROCLOCK, lockLink));
3103  }
3104 
3105  LWLockRelease(partitionLock);
3106 
3107  if (count > MaxBackends + max_prepared_xacts) /* should never happen */
3108  elog(PANIC, "too many conflicting locks found");
3109 
3110  vxids[count].backendId = InvalidBackendId;
3112  if (countp)
3113  *countp = count;
3114  return vxids;
3115 }
#define InvalidBackendId
Definition: backendid.h:23
#define offsetof(type, field)
Definition: c.h:738
#define lengthof(array)
Definition: c.h:745
#define ConflictsWithRelationFastPath(locktag, mode)
Definition: lock.c:233
uint32 LockTagHashCode(const LOCKTAG *locktag)
Definition: lock.c:517
uint16 LOCKMETHODID
Definition: lock.h:127
#define VirtualTransactionIdIsValid(vxid)
Definition: lock.h:72
#define InvalidLocalTransactionId
Definition: lock.h:70
#define VirtualTransactionIdEquals(vxid1, vxid2)
Definition: lock.h:76
#define GET_VXID_FROM_PGPROC(vxid, proc)
Definition: lock.h:82
int LOCKMASK
Definition: lockdefs.h:25
MemoryContext TopMemoryContext
Definition: mcxt.c:48
void * palloc0(Size size)
Definition: mcxt.c:1099
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:863
Pointer SHMQueueNext(const SHM_QUEUE *queue, const SHM_QUEUE *curElem, Size linkOffset)
Definition: shmqueue.c:145
uint8 locktag_lockmethodid
Definition: lock.h:174
int numLockModes
Definition: lock.h:115
LocalTransactionId localTransactionId
Definition: lock.h:67
BackendId backendId
Definition: lock.h:66
int max_prepared_xacts
Definition: twophase.c:117
#define InHotStandby
Definition: xlogutils.h:57

References PROC_HDR::allProcCount, PROC_HDR::allProcs, VirtualTransactionId::backendId, ConflictsWithRelationFastPath, LockMethodData::conflictTab, PGPROC::databaseId, elog, ERROR, FAST_PATH_GET_BITS, FAST_PATH_LOCKNUMBER_OFFSET, FP_LOCK_SLOTS_PER_BACKEND, PGPROC::fpInfoLock, PGPROC::fpRelId, GET_VXID_FROM_PGPROC, HASH_FIND, hash_search_with_hash_value(), PROCLOCK::holdMask, i, InHotStandby, InvalidBackendId, InvalidLocalTransactionId, lengthof, VirtualTransactionId::localTransactionId, LockHashPartitionLock, PROCLOCK::lockLink, LockMethodLockHash, LockMethods, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LockTagHashCode(), LW_SHARED, LWLockAcquire(), LWLockRelease(), max_prepared_xacts, MaxBackends, MemoryContextAlloc(), MyProc, PROCLOCKTAG::myProc, LockMethodData::numLockModes, offsetof, palloc0(), PANIC, ProcGlobal, LOCK::procLocks, SHMQueueNext(), PROCLOCK::tag, TopMemoryContext, VirtualTransactionIdEquals, and VirtualTransactionIdIsValid.

Referenced by ProcSleep(), ResolveRecoveryConflictWithLock(), and WaitForLockersMultiple().

◆ GetLockmodeName()

const char* GetLockmodeName ( LOCKMETHODID  lockmethodid,
LOCKMODE  mode 
)

Definition at line 4100 of file lock.c.

4101 {
4102  Assert(lockmethodid > 0 && lockmethodid < lengthof(LockMethods));
4103  Assert(mode > 0 && mode <= LockMethods[lockmethodid]->numLockModes);
4104  return LockMethods[lockmethodid]->lockModeNames[mode];
4105 }
const char *const * lockModeNames
Definition: lock.h:117

References Assert(), lengthof, LockMethods, LockMethodData::lockModeNames, and mode.

Referenced by CheckRelationLockedByMe(), DeadLockReport(), pg_lock_status(), and ProcSleep().

◆ GetLocksMethodTable()

LockMethod GetLocksMethodTable ( const LOCK lock)

Definition at line 487 of file lock.c.

488 {
489  LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*lock);
490 
491  Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
492  return LockMethods[lockmethodid];
493 }
#define LOCK_LOCKMETHOD(lock)
Definition: lock.h:316

References Assert(), lengthof, LOCK_LOCKMETHOD, and LockMethods.

Referenced by DeadLockCheck(), and FindLockCycleRecurseMember().

◆ GetLockStatusData()

LockData* GetLockStatusData ( void  )

Definition at line 3646 of file lock.c.

3647 {
3648  LockData *data;
3649  PROCLOCK *proclock;
3650  HASH_SEQ_STATUS seqstat;
3651  int els;
3652  int el;
3653  int i;
3654 
3655  data = (LockData *) palloc(sizeof(LockData));
3656 
3657  /* Guess how much space we'll need. */
3658  els = MaxBackends;
3659  el = 0;
3660  data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * els);
3661 
3662  /*
3663  * First, we iterate through the per-backend fast-path arrays, locking
3664  * them one at a time. This might produce an inconsistent picture of the
3665  * system state, but taking all of those LWLocks at the same time seems
3666  * impractical (in particular, note MAX_SIMUL_LWLOCKS). It shouldn't
3667  * matter too much, because none of these locks can be involved in lock
3668  * conflicts anyway - anything that might must be present in the main lock
3669  * table. (For the same reason, we don't sweat about making leaderPid
3670  * completely valid. We cannot safely dereference another backend's
3671  * lockGroupLeader field without holding all lock partition locks, and
3672  * it's not worth that.)
3673  */
3674  for (i = 0; i < ProcGlobal->allProcCount; ++i)
3675  {
3676  PGPROC *proc = &ProcGlobal->allProcs[i];
3677  uint32 f;
3678 
3680 
3681  for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; ++f)
3682  {
3683  LockInstanceData *instance;
3684  uint32 lockbits = FAST_PATH_GET_BITS(proc, f);
3685 
3686  /* Skip unallocated slots. */
3687  if (!lockbits)
3688  continue;
3689 
3690  if (el >= els)
3691  {
3692  els += MaxBackends;
3693  data->locks = (LockInstanceData *)
3694  repalloc(data->locks, sizeof(LockInstanceData) * els);
3695  }
3696 
3697  instance = &data->locks[el];
3698  SET_LOCKTAG_RELATION(instance->locktag, proc->databaseId,
3699  proc->fpRelId[f]);
3700  instance->holdMask = lockbits << FAST_PATH_LOCKNUMBER_OFFSET;
3701  instance->waitLockMode = NoLock;
3702  instance->backend = proc->backendId;
3703  instance->lxid = proc->lxid;
3704  instance->pid = proc->pid;
3705  instance->leaderPid = proc->pid;
3706  instance->fastpath = true;
3707 
3708  /*
3709  * Successfully taking fast path lock means there were no
3710  * conflicting locks.
3711  */
3712  instance->waitStart = 0;
3713 
3714  el++;
3715  }
3716 
3717  if (proc->fpVXIDLock)
3718  {
3719  VirtualTransactionId vxid;
3720  LockInstanceData *instance;
3721 
3722  if (el >= els)
3723  {
3724  els += MaxBackends;
3725  data->locks = (LockInstanceData *)
3726  repalloc(data->locks, sizeof(LockInstanceData) * els);
3727  }
3728 
3729  vxid.backendId = proc->backendId;
3731 
3732  instance = &data->locks[el];
3733  SET_LOCKTAG_VIRTUALTRANSACTION(instance->locktag, vxid);
3734  instance->holdMask = LOCKBIT_ON(ExclusiveLock);
3735  instance->waitLockMode = NoLock;
3736  instance->backend = proc->backendId;
3737  instance->lxid = proc->lxid;
3738  instance->pid = proc->pid;
3739  instance->leaderPid = proc->pid;
3740  instance->fastpath = true;
3741  instance->waitStart = 0;
3742 
3743  el++;
3744  }
3745 
3746  LWLockRelease(&proc->fpInfoLock);
3747  }
3748 
3749  /*
3750  * Next, acquire lock on the entire shared lock data structure. We do
3751  * this so that, at least for locks in the primary lock table, the state
3752  * will be self-consistent.
3753  *
3754  * Since this is a read-only operation, we take shared instead of
3755  * exclusive lock. There's not a whole lot of point to this, because all
3756  * the normal operations require exclusive lock, but it doesn't hurt
3757  * anything either. It will at least allow two backends to do
3758  * GetLockStatusData in parallel.
3759  *
3760  * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
3761  */
3762  for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
3764 
3765  /* Now we can safely count the number of proclocks */
3767  if (data->nelements > els)
3768  {
3769  els = data->nelements;
3770  data->locks = (LockInstanceData *)
3771  repalloc(data->locks, sizeof(LockInstanceData) * els);
3772  }
3773 
3774  /* Now scan the tables to copy the data */
3776 
3777  while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
3778  {
3779  PGPROC *proc = proclock->tag.myProc;
3780  LOCK *lock = proclock->tag.myLock;
3781  LockInstanceData *instance = &data->locks[el];
3782 
3783  memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
3784  instance->holdMask = proclock->holdMask;
3785  if (proc->waitLock == proclock->tag.myLock)
3786  instance->waitLockMode = proc->waitLockMode;
3787  else
3788  instance->waitLockMode = NoLock;
3789  instance->backend = proc->backendId;
3790  instance->lxid = proc->lxid;
3791  instance->pid = proc->pid;
3792  instance->leaderPid = proclock->groupLeader->pid;
3793  instance->fastpath = false;
3794  instance->waitStart = (TimestampTz) pg_atomic_read_u64(&proc->waitStart);
3795 
3796  el++;
3797  }
3798 
3799  /*
3800  * And release locks. We do this in reverse order for two reasons: (1)
3801  * Anyone else who needs more than one of the locks will be trying to lock
3802  * them in increasing order; we don't want to release the other process
3803  * until it can get all the locks it needs. (2) This avoids O(N^2)
3804  * behavior inside LWLockRelease.
3805  */
3806  for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
3808 
3809  Assert(el == data->nelements);
3810 
3811  return data;
3812 }
static uint64 pg_atomic_read_u64(volatile pg_atomic_uint64 *ptr)
Definition: atomics.h:429
int64 TimestampTz
Definition: timestamp.h:39
long hash_get_num_entries(HTAB *hashp)
Definition: dynahash.c:1382
#define SET_LOCKTAG_VIRTUALTRANSACTION(locktag, vxid)
Definition: lock.h:238
#define SET_LOCKTAG_RELATION(locktag, dboid, reloid)
Definition: lock.h:184
#define NoLock
Definition: lockdefs.h:34
#define ExclusiveLock
Definition: lockdefs.h:42
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1188
Definition: lock.h:459
LOCKMASK holdMask
Definition: lock.h:447
LOCKMODE waitLockMode
Definition: lock.h:448
bool fastpath
Definition: lock.h:455
LOCKTAG locktag
Definition: lock.h:446
TimestampTz waitStart
Definition: lock.h:451
int leaderPid
Definition: lock.h:454
BackendId backend
Definition: lock.h:449
LocalTransactionId lxid
Definition: lock.h:450
LocalTransactionId lxid
Definition: proc.h:181
pg_atomic_uint64 waitStart
Definition: proc.h:222
bool fpVXIDLock
Definition: proc.h:281
BackendId backendId
Definition: proc.h:191
int pid
Definition: proc.h:184
LOCK * waitLock
Definition: proc.h:217
LOCKMODE waitLockMode
Definition: proc.h:219
LocalTransactionId fpLocalTransactionId
Definition: proc.h:282
PGPROC * groupLeader
Definition: lock.h:367

References PROC_HDR::allProcCount, PROC_HDR::allProcs, Assert(), LockInstanceData::backend, VirtualTransactionId::backendId, PGPROC::backendId, data, PGPROC::databaseId, ExclusiveLock, FAST_PATH_GET_BITS, FAST_PATH_LOCKNUMBER_OFFSET, LockInstanceData::fastpath, FP_LOCK_SLOTS_PER_BACKEND, PGPROC::fpInfoLock, PGPROC::fpLocalTransactionId, PGPROC::fpRelId, PGPROC::fpVXIDLock, PROCLOCK::groupLeader, hash_get_num_entries(), hash_seq_init(), hash_seq_search(), PROCLOCK::holdMask, LockInstanceData::holdMask, i, LockInstanceData::leaderPid, VirtualTransactionId::localTransactionId, LOCKBIT_ON, LockHashPartitionLockByIndex, LockMethodProcLockHash, LockInstanceData::locktag, LW_SHARED, LWLockAcquire(), LWLockRelease(), LockInstanceData::lxid, PGPROC::lxid, MaxBackends, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, NoLock, NUM_LOCK_PARTITIONS, palloc(), pg_atomic_read_u64(), LockInstanceData::pid, PGPROC::pid, ProcGlobal, repalloc(), SET_LOCKTAG_RELATION, SET_LOCKTAG_VIRTUALTRANSACTION, LOCK::tag, PROCLOCK::tag, PGPROC::waitLock, LockInstanceData::waitLockMode, PGPROC::waitLockMode, LockInstanceData::waitStart, and PGPROC::waitStart.

Referenced by pg_lock_status().

◆ GetLockTagsMethodTable()

LockMethod GetLockTagsMethodTable ( const LOCKTAG locktag)

Definition at line 499 of file lock.c.

500 {
501  LOCKMETHODID lockmethodid = (LOCKMETHODID) locktag->locktag_lockmethodid;
502 
503  Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
504  return LockMethods[lockmethodid];
505 }

References Assert(), lengthof, LockMethods, and LOCKTAG::locktag_lockmethodid.

Referenced by pg_blocking_pids().

◆ GetRunningTransactionLocks()

xl_standby_lock* GetRunningTransactionLocks ( int *  nlocks)

Definition at line 4018 of file lock.c.

4019 {
4020  xl_standby_lock *accessExclusiveLocks;
4021  PROCLOCK *proclock;
4022  HASH_SEQ_STATUS seqstat;
4023  int i;
4024  int index;
4025  int els;
4026 
4027  /*
4028  * Acquire lock on the entire shared lock data structure.
4029  *
4030  * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
4031  */
4032  for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
4034 
4035  /* Now we can safely count the number of proclocks */
4037 
4038  /*
4039  * Allocating enough space for all locks in the lock table is overkill,
4040  * but it's more convenient and faster than having to enlarge the array.
4041  */
4042  accessExclusiveLocks = palloc(els * sizeof(xl_standby_lock));
4043 
4044  /* Now scan the tables to copy the data */
4046 
4047  /*
4048  * If lock is a currently granted AccessExclusiveLock then it will have
4049  * just one proclock holder, so locks are never accessed twice in this
4050  * particular case. Don't copy this code for use elsewhere because in the
4051  * general case this will give you duplicate locks when looking at
4052  * non-exclusive lock types.
4053  */
4054  index = 0;
4055  while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
4056  {
4057  /* make sure this definition matches the one used in LockAcquire */
4058  if ((proclock->holdMask & LOCKBIT_ON(AccessExclusiveLock)) &&
4059  proclock->tag.myLock->tag.locktag_type == LOCKTAG_RELATION)
4060  {
4061  PGPROC *proc = proclock->tag.myProc;
4062  LOCK *lock = proclock->tag.myLock;
4063  TransactionId xid = proc->xid;
4064 
4065  /*
4066  * Don't record locks for transactions if we know they have
4067  * already issued their WAL record for commit but not yet released
4068  * lock. It is still possible that we see locks held by already
4069  * complete transactions, if they haven't yet zeroed their xids.
4070  */
4071  if (!TransactionIdIsValid(xid))
4072  continue;
4073 
4074  accessExclusiveLocks[index].xid = xid;
4075  accessExclusiveLocks[index].dbOid = lock->tag.locktag_field1;
4076  accessExclusiveLocks[index].relOid = lock->tag.locktag_field2;
4077 
4078  index++;
4079  }
4080  }
4081 
4082  Assert(index <= els);
4083 
4084  /*
4085  * And release locks. We do this in reverse order for two reasons: (1)
4086  * Anyone else who needs more than one of the locks will be trying to lock
4087  * them in increasing order; we don't want to release the other process
4088  * until it can get all the locks it needs. (2) This avoids O(N^2)
4089  * behavior inside LWLockRelease.
4090  */
4091  for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
4093 
4094  *nlocks = index;
4095  return accessExclusiveLocks;
4096 }
uint32 TransactionId
Definition: c.h:598
#define AccessExclusiveLock
Definition: lockdefs.h:43
TransactionId xid
Definition: proc.h:171
Definition: type.h:90
TransactionId xid
Definition: lockdefs.h:51
#define TransactionIdIsValid(xid)
Definition: transam.h:41

References AccessExclusiveLock, Assert(), xl_standby_lock::dbOid, hash_get_num_entries(), hash_seq_init(), hash_seq_search(), PROCLOCK::holdMask, i, LOCKBIT_ON, LockHashPartitionLockByIndex, LockMethodProcLockHash, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG_RELATION, LOCKTAG::locktag_type, LW_SHARED, LWLockAcquire(), LWLockRelease(), PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, NUM_LOCK_PARTITIONS, palloc(), xl_standby_lock::relOid, LOCK::tag, PROCLOCK::tag, TransactionIdIsValid, xl_standby_lock::xid, and PGPROC::xid.

Referenced by LogStandbySnapshot().

◆ GetSingleProcBlockerStatusData()

static void GetSingleProcBlockerStatusData ( PGPROC blocked_proc,
BlockedProcsData data 
)
static

Definition at line 3918 of file lock.c.

3919 {
3920  LOCK *theLock = blocked_proc->waitLock;
3921  BlockedProcData *bproc;
3922  SHM_QUEUE *procLocks;
3923  PROCLOCK *proclock;
3924  PROC_QUEUE *waitQueue;
3925  PGPROC *proc;
3926  int queue_size;
3927  int i;
3928 
3929  /* Nothing to do if this proc is not blocked */
3930  if (theLock == NULL)
3931  return;
3932 
3933  /* Set up a procs[] element */
3934  bproc = &data->procs[data->nprocs++];
3935  bproc->pid = blocked_proc->pid;
3936  bproc->first_lock = data->nlocks;
3937  bproc->first_waiter = data->npids;
3938 
3939  /*
3940  * We may ignore the proc's fast-path arrays, since nothing in those could
3941  * be related to a contended lock.
3942  */
3943 
3944  /* Collect all PROCLOCKs associated with theLock */
3945  procLocks = &(theLock->procLocks);
3946  proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
3947  offsetof(PROCLOCK, lockLink));
3948  while (proclock)
3949  {
3950  PGPROC *proc = proclock->tag.myProc;
3951  LOCK *lock = proclock->tag.myLock;
3952  LockInstanceData *instance;
3953 
3954  if (data->nlocks >= data->maxlocks)
3955  {
3956  data->maxlocks += MaxBackends;
3957  data->locks = (LockInstanceData *)
3958  repalloc(data->locks, sizeof(LockInstanceData) * data->maxlocks);
3959  }
3960 
3961  instance = &data->locks[data->nlocks];
3962  memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
3963  instance->holdMask = proclock->holdMask;
3964  if (proc->waitLock == lock)
3965  instance->waitLockMode = proc->waitLockMode;
3966  else
3967  instance->waitLockMode = NoLock;
3968  instance->backend = proc->backendId;
3969  instance->lxid = proc->lxid;
3970  instance->pid = proc->pid;
3971  instance->leaderPid = proclock->groupLeader->pid;
3972  instance->fastpath = false;
3973  data->nlocks++;
3974 
3975  proclock = (PROCLOCK *) SHMQueueNext(procLocks, &proclock->lockLink,
3976  offsetof(PROCLOCK, lockLink));
3977  }
3978 
3979  /* Enlarge waiter_pids[] if it's too small to hold all wait queue PIDs */
3980  waitQueue = &(theLock->waitProcs);
3981  queue_size = waitQueue->size;
3982 
3983  if (queue_size > data->maxpids - data->npids)
3984  {
3985  data->maxpids = Max(data->maxpids + MaxBackends,
3986  data->npids + queue_size);
3987  data->waiter_pids = (int *) repalloc(data->waiter_pids,
3988  sizeof(int) * data->maxpids);
3989  }
3990 
3991  /* Collect PIDs from the lock's wait queue, stopping at blocked_proc */
3992  proc = (PGPROC *) waitQueue->links.next;
3993  for (i = 0; i < queue_size; i++)
3994  {
3995  if (proc == blocked_proc)
3996  break;
3997  data->waiter_pids[data->npids++] = proc->pid;
3998  proc = (PGPROC *) proc->links.next;
3999  }
4000 
4001  bproc->num_locks = data->nlocks - bproc->first_lock;
4002  bproc->num_waiters = data->npids - bproc->first_waiter;
4003 }
#define Max(x, y)
Definition: c.h:991
int first_lock
Definition: lock.h:469
int first_waiter
Definition: lock.h:473
int num_waiters
Definition: lock.h:474
int num_locks
Definition: lock.h:470
PROC_QUEUE waitProcs
Definition: lock.h:309
SHM_QUEUE links
Definition: proc.h:162
SHM_QUEUE links
Definition: lock.h:32
int size
Definition: lock.h:33
struct SHM_QUEUE * next
Definition: shmem.h:31

References LockInstanceData::backend, PGPROC::backendId, data, LockInstanceData::fastpath, BlockedProcData::first_lock, BlockedProcData::first_waiter, PROCLOCK::groupLeader, PROCLOCK::holdMask, LockInstanceData::holdMask, i, LockInstanceData::leaderPid, PROC_QUEUE::links, PGPROC::links, PROCLOCK::lockLink, LockInstanceData::locktag, LockInstanceData::lxid, PGPROC::lxid, Max, MaxBackends, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, SHM_QUEUE::next, NoLock, BlockedProcData::num_locks, BlockedProcData::num_waiters, offsetof, LockInstanceData::pid, BlockedProcData::pid, PGPROC::pid, LOCK::procLocks, repalloc(), SHMQueueNext(), PROC_QUEUE::size, LOCK::tag, PROCLOCK::tag, PGPROC::waitLock, LockInstanceData::waitLockMode, PGPROC::waitLockMode, and LOCK::waitProcs.

Referenced by GetBlockerStatusData().

◆ GrantAwaitedLock()

void GrantAwaitedLock ( void  )

Definition at line 1786 of file lock.c.

1787 {
1789 }
static LOCALLOCK * awaitedLock
Definition: lock.c:288
static ResourceOwner awaitedOwner
Definition: lock.c:289
static void GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner)
Definition: lock.c:1689

References awaitedLock, awaitedOwner, and GrantLockLocal().

Referenced by LockErrorCleanup(), and ProcSleep().

◆ GrantLock()

void GrantLock ( LOCK lock,
PROCLOCK proclock,
LOCKMODE  lockmode 
)

Definition at line 1555 of file lock.c.

1556 {
1557  lock->nGranted++;
1558  lock->granted[lockmode]++;
1559  lock->grantMask |= LOCKBIT_ON(lockmode);
1560  if (lock->granted[lockmode] == lock->requested[lockmode])
1561  lock->waitMask &= LOCKBIT_OFF(lockmode);
1562  proclock->holdMask |= LOCKBIT_ON(lockmode);
1563  LOCK_PRINT("GrantLock", lock, lockmode);
1564  Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
1565  Assert(lock->nGranted <= lock->nRequested);
1566 }
#define LOCKBIT_OFF(lockmode)
Definition: lock.h:90
int requested[MAX_LOCKMODES]
Definition: lock.h:310
int granted[MAX_LOCKMODES]
Definition: lock.h:312
LOCKMASK grantMask
Definition: lock.h:306
LOCKMASK waitMask
Definition: lock.h:307
int nGranted
Definition: lock.h:313

References Assert(), LOCK::granted, LOCK::grantMask, PROCLOCK::holdMask, LOCK_PRINT, LOCKBIT_OFF, LOCKBIT_ON, LOCK::nGranted, LOCK::nRequested, LOCK::requested, and LOCK::waitMask.

Referenced by FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), lock_twophase_recover(), LockAcquireExtended(), ProcLockWakeup(), ProcSleep(), and VirtualXactLock().

◆ GrantLockLocal()

static void GrantLockLocal ( LOCALLOCK locallock,
ResourceOwner  owner 
)
static

Definition at line 1689 of file lock.c.

1690 {
1691  LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
1692  int i;
1693 
1694  Assert(locallock->numLockOwners < locallock->maxLockOwners);
1695  /* Count the total */
1696  locallock->nLocks++;
1697  /* Count the per-owner lock */
1698  for (i = 0; i < locallock->numLockOwners; i++)
1699  {
1700  if (lockOwners[i].owner == owner)
1701  {
1702  lockOwners[i].nLocks++;
1703  return;
1704  }
1705  }
1706  lockOwners[i].owner = owner;
1707  lockOwners[i].nLocks = 1;
1708  locallock->numLockOwners++;
1709  if (owner != NULL)
1710  ResourceOwnerRememberLock(owner, locallock);
1711 
1712  /* Indicate that the lock is acquired for certain types of locks. */
1713  CheckAndSetLockHeld(locallock, true);
1714 }
static void CheckAndSetLockHeld(LOCALLOCK *locallock, bool acquired)
Definition: lock.c:1352
void ResourceOwnerRememberLock(ResourceOwner owner, LOCALLOCK *locallock)
Definition: resowner.c:985
int64 nLocks
Definition: lock.h:415
struct ResourceOwnerData * owner
Definition: lock.h:414
int maxLockOwners
Definition: lock.h:429

References Assert(), CheckAndSetLockHeld(), i, LOCALLOCK::lockOwners, LOCALLOCK::maxLockOwners, LOCALLOCKOWNER::nLocks, LOCALLOCK::nLocks, LOCALLOCK::numLockOwners, LOCALLOCKOWNER::owner, and ResourceOwnerRememberLock().

Referenced by GrantAwaitedLock(), and LockAcquireExtended().

◆ InitLocks()

void InitLocks ( void  )

Definition at line 405 of file lock.c.

406 {
407  HASHCTL info;
408  long init_table_size,
409  max_table_size;
410  bool found;
411 
412  /*
413  * Compute init/max size to request for lock hashtables. Note these
414  * calculations must agree with LockShmemSize!
415  */
416  max_table_size = NLOCKENTS();
417  init_table_size = max_table_size / 2;
418 
419  /*
420  * Allocate hash table for LOCK structs. This stores per-locked-object
421  * information.
422  */
423  info.keysize = sizeof(LOCKTAG);
424  info.entrysize = sizeof(LOCK);
426 
427  LockMethodLockHash = ShmemInitHash("LOCK hash",
428  init_table_size,
429  max_table_size,
430  &info,
432 
433  /* Assume an average of 2 holders per lock */
434  max_table_size *= 2;
435  init_table_size *= 2;
436 
437  /*
438  * Allocate hash table for PROCLOCK structs. This stores
439  * per-lock-per-holder information.
440  */
441  info.keysize = sizeof(PROCLOCKTAG);
442  info.entrysize = sizeof(PROCLOCK);
443  info.hash = proclock_hash;
445 
446  LockMethodProcLockHash = ShmemInitHash("PROCLOCK hash",
447  init_table_size,
448  max_table_size,
449  &info,
451 
452  /*
453  * Allocate fast-path structures.
454  */
456  ShmemInitStruct("Fast Path Strong Relation Lock Data",
457  sizeof(FastPathStrongRelationLockData), &found);
458  if (!found)
460 
461  /*
462  * Allocate non-shared hash table for LOCALLOCK structs. This stores lock
463  * counts and resource owner information.
464  *
465  * The non-shared table could already exist in this process (this occurs
466  * when the postmaster is recreating shared memory after a backend crash).
467  * If so, delete and recreate it. (We could simply leave it, since it
468  * ought to be empty in the postmaster, but for safety let's zap it.)
469  */
472 
473  info.keysize = sizeof(LOCALLOCKTAG);
474  info.entrysize = sizeof(LOCALLOCK);
475 
476  LockMethodLocalHash = hash_create("LOCALLOCK hash",
477  16,
478  &info,
480 }
#define HASH_FUNCTION
Definition: hsearch.h:98
#define HASH_PARTITION
Definition: hsearch.h:92
#define NLOCKENTS()
Definition: lock.c:57
static uint32 proclock_hash(const void *key, Size keysize)
Definition: lock.c:534
struct LOCALLOCK LOCALLOCK
struct LOCK LOCK
struct PROCLOCK PROCLOCK
struct PROCLOCKTAG PROCLOCKTAG
struct LOCALLOCKTAG LOCALLOCKTAG
void * ShmemInitStruct(const char *name, Size size, bool *foundPtr)
Definition: shmem.c:396
HTAB * ShmemInitHash(const char *name, long init_size, long max_size, HASHCTL *infoP, int hash_flags)
Definition: shmem.c:341
#define SpinLockInit(lock)
Definition: spin.h:60
HashValueFunc hash
Definition: hsearch.h:78
long num_partitions
Definition: hsearch.h:68

References HASHCTL::entrysize, FastPathStrongRelationLocks, HASHCTL::hash, HASH_BLOBS, hash_create(), hash_destroy(), HASH_ELEM, HASH_FUNCTION, HASH_PARTITION, HASHCTL::keysize, LockMethodLocalHash, LockMethodLockHash, LockMethodProcLockHash, FastPathStrongRelationLockData::mutex, NLOCKENTS, NUM_LOCK_PARTITIONS, HASHCTL::num_partitions, proclock_hash(), ShmemInitHash(), ShmemInitStruct(), and SpinLockInit.

Referenced by CreateSharedMemoryAndSemaphores().

◆ lock_twophase_postabort()

void lock_twophase_postabort ( TransactionId  xid,
uint16  info,
void *  recdata,
uint32  len 
)

Definition at line 4452 of file lock.c.

4454 {
4455  lock_twophase_postcommit(xid, info, recdata, len);
4456 }
void lock_twophase_postcommit(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4426
const void size_t len

References len, and lock_twophase_postcommit().

◆ lock_twophase_postcommit()

void lock_twophase_postcommit ( TransactionId  xid,
uint16  info,
void *  recdata,
uint32  len 
)

Definition at line 4426 of file lock.c.

4428 {
4429  TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
4430  PGPROC *proc = TwoPhaseGetDummyProc(xid, true);
4431  LOCKTAG *locktag;
4432  LOCKMETHODID lockmethodid;
4433  LockMethod lockMethodTable;
4434 
4435  Assert(len == sizeof(TwoPhaseLockRecord));
4436  locktag = &rec->locktag;
4437  lockmethodid = locktag->locktag_lockmethodid;
4438 
4439  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
4440  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
4441  lockMethodTable = LockMethods[lockmethodid];
4442 
4443  LockRefindAndRelease(lockMethodTable, proc, locktag, rec->lockmode, true);
4444 }
static void LockRefindAndRelease(LockMethod lockMethodTable, PGPROC *proc, LOCKTAG *locktag, LOCKMODE lockmode, bool decrement_strong_lock_count)
Definition: lock.c:3129
PGPROC * TwoPhaseGetDummyProc(TransactionId xid, bool lock_held)
Definition: twophase.c:935

References Assert(), elog, ERROR, len, lengthof, LockMethods, TwoPhaseLockRecord::lockmode, LockRefindAndRelease(), TwoPhaseLockRecord::locktag, LOCKTAG::locktag_lockmethodid, and TwoPhaseGetDummyProc().

Referenced by lock_twophase_postabort().

◆ lock_twophase_recover()

void lock_twophase_recover ( TransactionId  xid,
uint16  info,
void *  recdata,
uint32  len 
)

Definition at line 4213 of file lock.c.

4215 {
4216  TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
4217  PGPROC *proc = TwoPhaseGetDummyProc(xid, false);
4218  LOCKTAG *locktag;
4219  LOCKMODE lockmode;
4220  LOCKMETHODID lockmethodid;
4221  LOCK *lock;
4222  PROCLOCK *proclock;
4223  PROCLOCKTAG proclocktag;
4224  bool found;
4225  uint32 hashcode;
4226  uint32 proclock_hashcode;
4227  int partition;
4228  LWLock *partitionLock;
4229  LockMethod lockMethodTable;
4230 
4231  Assert(len == sizeof(TwoPhaseLockRecord));
4232  locktag = &rec->locktag;
4233  lockmode = rec->lockmode;
4234  lockmethodid = locktag->locktag_lockmethodid;
4235 
4236  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
4237  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
4238  lockMethodTable = LockMethods[lockmethodid];
4239 
4240  hashcode = LockTagHashCode(locktag);
4241  partition = LockHashPartition(hashcode);
4242  partitionLock = LockHashPartitionLock(hashcode);
4243 
4244  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
4245 
4246  /*
4247  * Find or create a lock with this tag.
4248  */
4250  (void *) locktag,
4251  hashcode,
4253  &found);
4254  if (!lock)
4255  {
4256  LWLockRelease(partitionLock);
4257  ereport(ERROR,
4258  (errcode(ERRCODE_OUT_OF_MEMORY),
4259  errmsg("out of shared memory"),
4260  errhint("You might need to increase max_locks_per_transaction.")));
4261  }
4262 
4263  /*
4264  * if it's a new lock object, initialize it
4265  */
4266  if (!found)
4267  {
4268  lock->grantMask = 0;
4269  lock->waitMask = 0;
4270  SHMQueueInit(&(lock->procLocks));
4271  ProcQueueInit(&(lock->waitProcs));
4272  lock->nRequested = 0;
4273  lock->nGranted = 0;
4274  MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
4275  MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
4276  LOCK_PRINT("lock_twophase_recover: new", lock, lockmode);
4277  }
4278  else
4279  {
4280  LOCK_PRINT("lock_twophase_recover: found", lock, lockmode);
4281  Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
4282  Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
4283  Assert(lock->nGranted <= lock->nRequested);
4284  }
4285 
4286  /*
4287  * Create the hash key for the proclock table.
4288  */
4289  proclocktag.myLock = lock;
4290  proclocktag.myProc = proc;
4291 
4292  proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
4293 
4294  /*
4295  * Find or create a proclock entry with this tag
4296  */
4298  (void *) &proclocktag,
4299  proclock_hashcode,
4301  &found);
4302  if (!proclock)
4303  {
4304  /* Oops, not enough shmem for the proclock */
4305  if (lock->nRequested == 0)
4306  {
4307  /*
4308  * There are no other requestors of this lock, so garbage-collect
4309  * the lock object. We *must* do this to avoid a permanent leak
4310  * of shared memory, because there won't be anything to cause
4311  * anyone to release the lock object later.
4312  */
4313  Assert(SHMQueueEmpty(&(lock->procLocks)));
4315  (void *) &(lock->tag),
4316  hashcode,
4317  HASH_REMOVE,
4318  NULL))
4319  elog(PANIC, "lock table corrupted");
4320  }
4321  LWLockRelease(partitionLock);
4322  ereport(ERROR,
4323  (errcode(ERRCODE_OUT_OF_MEMORY),
4324  errmsg("out of shared memory"),
4325  errhint("You might need to increase max_locks_per_transaction.")));
4326  }
4327 
4328  /*
4329  * If new, initialize the new entry
4330  */
4331  if (!found)
4332  {
4333  Assert(proc->lockGroupLeader == NULL);
4334  proclock->groupLeader = proc;
4335  proclock->holdMask = 0;
4336  proclock->releaseMask = 0;
4337  /* Add proclock to appropriate lists */
4338  SHMQueueInsertBefore(&lock->procLocks, &proclock->lockLink);
4339  SHMQueueInsertBefore(&(proc->myProcLocks[partition]),
4340  &proclock->procLink);
4341  PROCLOCK_PRINT("lock_twophase_recover: new", proclock);
4342  }
4343  else
4344  {
4345  PROCLOCK_PRINT("lock_twophase_recover: found", proclock);
4346  Assert((proclock->holdMask & ~lock->grantMask) == 0);
4347  }
4348 
4349  /*
4350  * lock->nRequested and lock->requested[] count the total number of
4351  * requests, whether granted or waiting, so increment those immediately.
4352  */
4353  lock->nRequested++;
4354  lock->requested[lockmode]++;
4355  Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
4356 
4357  /*
4358  * We shouldn't already hold the desired lock.
4359  */
4360  if (proclock->holdMask & LOCKBIT_ON(lockmode))
4361  elog(ERROR, "lock %s on object %u/%u/%u is already held",
4362  lockMethodTable->lockModeNames[lockmode],
4363  lock->tag.locktag_field1, lock->tag.locktag_field2,
4364  lock->tag.locktag_field3);
4365 
4366  /*
4367  * We ignore any possible conflicts and just grant ourselves the lock. Not
4368  * only because we don't bother, but also to avoid deadlocks when
4369  * switching from standby to normal mode. See function comment.
4370  */
4371  GrantLock(lock, proclock, lockmode);
4372 
4373  /*
4374  * Bump strong lock count, to make sure any fast-path lock requests won't
4375  * be granted without consulting the primary lock table.
4376  */
4377  if (ConflictsWithRelationFastPath(&lock->tag, lockmode))
4378  {
4379  uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
4380 
4382  FastPathStrongRelationLocks->count[fasthashcode]++;
4384  }
4385 
4386  LWLockRelease(partitionLock);
4387 }
#define MemSet(start, val, len)
Definition: c.h:1019
@ HASH_ENTER_NULL
Definition: hsearch.h:116
#define MAX_LOCKMODES
Definition: lock.h:87
#define LockHashPartition(hashcode)
Definition: lock.h:517
int LOCKMODE
Definition: lockdefs.h:26
void SHMQueueInit(SHM_QUEUE *queue)
Definition: shmqueue.c:36
void SHMQueueInsertBefore(SHM_QUEUE *queue, SHM_QUEUE *elem)
Definition: shmqueue.c:89
void ProcQueueInit(PROC_QUEUE *queue)
Definition: proc.c:1021
uint32 locktag_field3
Definition: lock.h:171
SHM_QUEUE myProcLocks[NUM_LOCK_PARTITIONS]
Definition: proc.h:246
LOCKMASK releaseMask
Definition: lock.h:369

References Assert(), ConflictsWithRelationFastPath, FastPathStrongRelationLockData::count, elog, ereport, errcode(), errhint(), errmsg(), ERROR, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, LOCK::granted, GrantLock(), LOCK::grantMask, PROCLOCK::groupLeader, HASH_ENTER_NULL, HASH_REMOVE, hash_search_with_hash_value(), PROCLOCK::holdMask, len, lengthof, LOCK_PRINT, LOCKBIT_ON, PGPROC::lockGroupLeader, LockHashPartition, LockHashPartitionLock, PROCLOCK::lockLink, LockMethodLockHash, LockMethodProcLockHash, LockMethods, TwoPhaseLockRecord::lockmode, LockMethodData::lockModeNames, TwoPhaseLockRecord::locktag, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_field3, LOCKTAG::locktag_lockmethodid, LockTagHashCode(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MAX_LOCKMODES, MemSet, FastPathStrongRelationLockData::mutex, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, PGPROC::myProcLocks, LOCK::nGranted, LOCK::nRequested, PANIC, PROCLOCK::procLink, PROCLOCK_PRINT, ProcLockHashCode(), LOCK::procLocks, ProcQueueInit(), PROCLOCK::releaseMask, LOCK::requested, SHMQueueEmpty(), SHMQueueInit(), SHMQueueInsertBefore(), SpinLockAcquire, SpinLockRelease, LOCK::tag, TwoPhaseGetDummyProc(), LOCK::waitMask, and LOCK::waitProcs.

◆ lock_twophase_standby_recover()

void lock_twophase_standby_recover ( TransactionId  xid,
uint16  info,
void *  recdata,
uint32  len 
)

Definition at line 4394 of file lock.c.

4396 {
4397  TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
4398  LOCKTAG *locktag;
4399  LOCKMODE lockmode;
4400  LOCKMETHODID lockmethodid;
4401 
4402  Assert(len == sizeof(TwoPhaseLockRecord));
4403  locktag = &rec->locktag;
4404  lockmode = rec->lockmode;
4405  lockmethodid = locktag->locktag_lockmethodid;
4406 
4407  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
4408  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
4409 
4410  if (lockmode == AccessExclusiveLock &&
4411  locktag->locktag_type == LOCKTAG_RELATION)
4412  {
4414  locktag->locktag_field1 /* dboid */ ,
4415  locktag->locktag_field2 /* reloid */ );
4416  }
4417 }
void StandbyAcquireAccessExclusiveLock(TransactionId xid, Oid dbOid, Oid relOid)
Definition: standby.c:948

References AccessExclusiveLock, Assert(), elog, ERROR, len, lengthof, LockMethods, TwoPhaseLockRecord::lockmode, TwoPhaseLockRecord::locktag, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LOCKTAG_RELATION, LOCKTAG::locktag_type, and StandbyAcquireAccessExclusiveLock().

◆ LockAcquire()

LockAcquireResult LockAcquire ( const LOCKTAG locktag,
LOCKMODE  lockmode,
bool  sessionLock,
bool  dontWait 
)

◆ LockAcquireExtended()

LockAcquireResult LockAcquireExtended ( const LOCKTAG locktag,
LOCKMODE  lockmode,
bool  sessionLock,
bool  dontWait,
bool  reportMemoryError,
LOCALLOCK **  locallockp 
)

Definition at line 771 of file lock.c.

777 {
778  LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
779  LockMethod lockMethodTable;
780  LOCALLOCKTAG localtag;
781  LOCALLOCK *locallock;
782  LOCK *lock;
783  PROCLOCK *proclock;
784  bool found;
785  ResourceOwner owner;
786  uint32 hashcode;
787  LWLock *partitionLock;
788  bool found_conflict;
789  bool log_lock = false;
790 
791  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
792  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
793  lockMethodTable = LockMethods[lockmethodid];
794  if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
795  elog(ERROR, "unrecognized lock mode: %d", lockmode);
796 
797  if (RecoveryInProgress() && !InRecovery &&
798  (locktag->locktag_type == LOCKTAG_OBJECT ||
799  locktag->locktag_type == LOCKTAG_RELATION) &&
800  lockmode > RowExclusiveLock)
801  ereport(ERROR,
802  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
803  errmsg("cannot acquire lock mode %s on database objects while recovery is in progress",
804  lockMethodTable->lockModeNames[lockmode]),
805  errhint("Only RowExclusiveLock or less can be acquired on database objects during recovery.")));
806 
807 #ifdef LOCK_DEBUG
808  if (LOCK_DEBUG_ENABLED(locktag))
809  elog(LOG, "LockAcquire: lock [%u,%u] %s",
810  locktag->locktag_field1, locktag->locktag_field2,
811  lockMethodTable->lockModeNames[lockmode]);
812 #endif
813 
814  /* Identify owner for lock */
815  if (sessionLock)
816  owner = NULL;
817  else
818  owner = CurrentResourceOwner;
819 
820  /*
821  * Find or create a LOCALLOCK entry for this lock and lockmode
822  */
823  MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
824  localtag.lock = *locktag;
825  localtag.mode = lockmode;
826 
827  locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
828  (void *) &localtag,
829  HASH_ENTER, &found);
830 
831  /*
832  * if it's a new locallock object, initialize it
833  */
834  if (!found)
835  {
836  locallock->lock = NULL;
837  locallock->proclock = NULL;
838  locallock->hashcode = LockTagHashCode(&(localtag.lock));
839  locallock->nLocks = 0;
840  locallock->holdsStrongLockCount = false;
841  locallock->lockCleared = false;
842  locallock->numLockOwners = 0;
843  locallock->maxLockOwners = 8;
844  locallock->lockOwners = NULL; /* in case next line fails */
845  locallock->lockOwners = (LOCALLOCKOWNER *)
847  locallock->maxLockOwners * sizeof(LOCALLOCKOWNER));
848  }
849  else
850  {
851  /* Make sure there will be room to remember the lock */
852  if (locallock->numLockOwners >= locallock->maxLockOwners)
853  {
854  int newsize = locallock->maxLockOwners * 2;
855 
856  locallock->lockOwners = (LOCALLOCKOWNER *)
857  repalloc(locallock->lockOwners,
858  newsize * sizeof(LOCALLOCKOWNER));
859  locallock->maxLockOwners = newsize;
860  }
861  }
862  hashcode = locallock->hashcode;
863 
864  if (locallockp)
865  *locallockp = locallock;
866 
867  /*
868  * If we already hold the lock, we can just increase the count locally.
869  *
870  * If lockCleared is already set, caller need not worry about absorbing
871  * sinval messages related to the lock's object.
872  */
873  if (locallock->nLocks > 0)
874  {
875  GrantLockLocal(locallock, owner);
876  if (locallock->lockCleared)
878  else
880  }
881 
882  /*
883  * We don't acquire any other heavyweight lock while holding the relation
884  * extension lock. We do allow to acquire the same relation extension
885  * lock more than once but that case won't reach here.
886  */
887  Assert(!IsRelationExtensionLockHeld);
888 
889  /*
890  * We don't acquire any other heavyweight lock while holding the page lock
891  * except for relation extension.
892  */
893  Assert(!IsPageLockHeld ||
894  (locktag->locktag_type == LOCKTAG_RELATION_EXTEND));
895 
896  /*
897  * Prepare to emit a WAL record if acquisition of this lock needs to be
898  * replayed in a standby server.
899  *
900  * Here we prepare to log; after lock is acquired we'll issue log record.
901  * This arrangement simplifies error recovery in case the preparation step
902  * fails.
903  *
904  * Only AccessExclusiveLocks can conflict with lock types that read-only
905  * transactions can acquire in a standby server. Make sure this definition
906  * matches the one in GetRunningTransactionLocks().
907  */
908  if (lockmode >= AccessExclusiveLock &&
909  locktag->locktag_type == LOCKTAG_RELATION &&
910  !RecoveryInProgress() &&
912  {
914  log_lock = true;
915  }
916 
917  /*
918  * Attempt to take lock via fast path, if eligible. But if we remember
919  * having filled up the fast path array, we don't attempt to make any
920  * further use of it until we release some locks. It's possible that some
921  * other backend has transferred some of those locks to the shared hash
922  * table, leaving space free, but it's not worth acquiring the LWLock just
923  * to check. It's also possible that we're acquiring a second or third
924  * lock type on a relation we have already locked using the fast-path, but
925  * for now we don't worry about that case either.
926  */
927  if (EligibleForRelationFastPath(locktag, lockmode) &&
929  {
930  uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
931  bool acquired;
932 
933  /*
934  * LWLockAcquire acts as a memory sequencing point, so it's safe to
935  * assume that any strong locker whose increment to
936  * FastPathStrongRelationLocks->counts becomes visible after we test
937  * it has yet to begin to transfer fast-path locks.
938  */
940  if (FastPathStrongRelationLocks->count[fasthashcode] != 0)
941  acquired = false;
942  else
943  acquired = FastPathGrantRelationLock(locktag->locktag_field2,
944  lockmode);
946  if (acquired)
947  {
948  /*
949  * The locallock might contain stale pointers to some old shared
950  * objects; we MUST reset these to null before considering the
951  * lock to be acquired via fast-path.
952  */
953  locallock->lock = NULL;
954  locallock->proclock = NULL;
955  GrantLockLocal(locallock, owner);
956  return LOCKACQUIRE_OK;
957  }
958  }
959 
960  /*
961  * If this lock could potentially have been taken via the fast-path by
962  * some other backend, we must (temporarily) disable further use of the
963  * fast-path for this lock tag, and migrate any locks already taken via
964  * this method to the main lock table.
965  */
966  if (ConflictsWithRelationFastPath(locktag, lockmode))
967  {
968  uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
969 
970  BeginStrongLockAcquire(locallock, fasthashcode);
971  if (!FastPathTransferRelationLocks(lockMethodTable, locktag,
972  hashcode))
973  {
975  if (locallock->nLocks == 0)
976  RemoveLocalLock(locallock);
977  if (locallockp)
978  *locallockp = NULL;
979  if (reportMemoryError)
980  ereport(ERROR,
981  (errcode(ERRCODE_OUT_OF_MEMORY),
982  errmsg("out of shared memory"),
983  errhint("You might need to increase max_locks_per_transaction.")));
984  else
985  return LOCKACQUIRE_NOT_AVAIL;
986  }
987  }
988 
989  /*
990  * We didn't find the lock in our LOCALLOCK table, and we didn't manage to
991  * take it via the fast-path, either, so we've got to mess with the shared
992  * lock table.
993  */
994  partitionLock = LockHashPartitionLock(hashcode);
995 
996  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
997 
998  /*
999  * Find or create lock and proclock entries with this tag
1000  *
1001  * Note: if the locallock object already existed, it might have a pointer
1002  * to the lock already ... but we should not assume that that pointer is
1003  * valid, since a lock object with zero hold and request counts can go
1004  * away anytime. So we have to use SetupLockInTable() to recompute the
1005  * lock and proclock pointers, even if they're already set.
1006  */
1007  proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
1008  hashcode, lockmode);
1009  if (!proclock)
1010  {
1012  LWLockRelease(partitionLock);
1013  if (locallock->nLocks == 0)
1014  RemoveLocalLock(locallock);
1015  if (locallockp)
1016  *locallockp = NULL;
1017  if (reportMemoryError)
1018  ereport(ERROR,
1019  (errcode(ERRCODE_OUT_OF_MEMORY),
1020  errmsg("out of shared memory"),
1021  errhint("You might need to increase max_locks_per_transaction.")));
1022  else
1023  return LOCKACQUIRE_NOT_AVAIL;
1024  }
1025  locallock->proclock = proclock;
1026  lock = proclock->tag.myLock;
1027  locallock->lock = lock;
1028 
1029  /*
1030  * If lock requested conflicts with locks requested by waiters, must join
1031  * wait queue. Otherwise, check for conflict with already-held locks.
1032  * (That's last because most complex check.)
1033  */
1034  if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
1035  found_conflict = true;
1036  else
1037  found_conflict = LockCheckConflicts(lockMethodTable, lockmode,
1038  lock, proclock);
1039 
1040  if (!found_conflict)
1041  {
1042  /* No conflict with held or previously requested locks */
1043  GrantLock(lock, proclock, lockmode);
1044  GrantLockLocal(locallock, owner);
1045  }
1046  else
1047  {
1048  /*
1049  * We can't acquire the lock immediately. If caller specified no
1050  * blocking, remove useless table entries and return
1051  * LOCKACQUIRE_NOT_AVAIL without waiting.
1052  */
1053  if (dontWait)
1054  {
1056  if (proclock->holdMask == 0)
1057  {
1058  uint32 proclock_hashcode;
1059 
1060  proclock_hashcode = ProcLockHashCode(&proclock->tag, hashcode);
1061  SHMQueueDelete(&proclock->lockLink);
1062  SHMQueueDelete(&proclock->procLink);
1064  (void *) &(proclock->tag),
1065  proclock_hashcode,
1066  HASH_REMOVE,
1067  NULL))
1068  elog(PANIC, "proclock table corrupted");
1069  }
1070  else
1071  PROCLOCK_PRINT("LockAcquire: NOWAIT", proclock);
1072  lock->nRequested--;
1073  lock->requested[lockmode]--;
1074  LOCK_PRINT("LockAcquire: conditional lock failed", lock, lockmode);
1075  Assert((lock->nRequested > 0) && (lock->requested[lockmode] >= 0));
1076  Assert(lock->nGranted <= lock->nRequested);
1077  LWLockRelease(partitionLock);
1078  if (locallock->nLocks == 0)
1079  RemoveLocalLock(locallock);
1080  if (locallockp)
1081  *locallockp = NULL;
1082  return LOCKACQUIRE_NOT_AVAIL;
1083  }
1084 
1085  /*
1086  * Set bitmask of locks this process already holds on this object.
1087  */
1088  MyProc->heldLocks = proclock->holdMask;
1089 
1090  /*
1091  * Sleep till someone wakes me up.
1092  */
1093 
1094  TRACE_POSTGRESQL_LOCK_WAIT_START(locktag->locktag_field1,
1095  locktag->locktag_field2,
1096  locktag->locktag_field3,
1097  locktag->locktag_field4,
1098  locktag->locktag_type,
1099  lockmode);
1100 
1101  WaitOnLock(locallock, owner);
1102 
1103  TRACE_POSTGRESQL_LOCK_WAIT_DONE(locktag->locktag_field1,
1104  locktag->locktag_field2,
1105  locktag->locktag_field3,
1106  locktag->locktag_field4,
1107  locktag->locktag_type,
1108  lockmode);
1109 
1110  /*
1111  * NOTE: do not do any material change of state between here and
1112  * return. All required changes in locktable state must have been
1113  * done when the lock was granted to us --- see notes in WaitOnLock.
1114  */
1115 
1116  /*
1117  * Check the proclock entry status, in case something in the ipc
1118  * communication doesn't work correctly.
1119  */
1120  if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
1121  {
1123  PROCLOCK_PRINT("LockAcquire: INCONSISTENT", proclock);
1124  LOCK_PRINT("LockAcquire: INCONSISTENT", lock, lockmode);
1125  /* Should we retry ? */
1126  LWLockRelease(partitionLock);
1127  elog(ERROR, "LockAcquire failed");
1128  }
1129  PROCLOCK_PRINT("LockAcquire: granted", proclock);
1130  LOCK_PRINT("LockAcquire: granted", lock, lockmode);
1131  }
1132 
1133  /*
1134  * Lock state is fully up-to-date now; if we error out after this, no
1135  * special error cleanup is required.
1136  */
1138 
1139  LWLockRelease(partitionLock);
1140 
1141  /*
1142  * Emit a WAL record if acquisition of this lock needs to be replayed in a
1143  * standby server.
1144  */
1145  if (log_lock)
1146  {
1147  /*
1148  * Decode the locktag back to the original values, to avoid sending
1149  * lots of empty bytes with every message. See lock.h to check how a
1150  * locktag is defined for LOCKTAG_RELATION
1151  */
1153  locktag->locktag_field2);
1154  }
1155 
1156  return LOCKACQUIRE_OK;
1157 }
#define LOG
Definition: elog.h:25
static void RemoveLocalLock(LOCALLOCK *locallock)
Definition: lock.c:1367
static bool FastPathTransferRelationLocks(LockMethod lockMethodTable, const LOCKTAG *locktag, uint32 hashcode)
Definition: lock.c:2722
void AbortStrongLockAcquire(void)
Definition: lock.c:1757
static bool FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode)
Definition: lock.c:2655
static void WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
Definition: lock.c:1814
#define EligibleForRelationFastPath(locktag, mode)
Definition: lock.c:227
static void BeginStrongLockAcquire(LOCALLOCK *locallock, uint32 fasthashcode)
Definition: lock.c:1721
bool LockCheckConflicts(LockMethod lockMethodTable, LOCKMODE lockmode, LOCK *lock, PROCLOCK *proclock)
Definition: lock.c:1420
static void FinishStrongLockAcquire(void)
Definition: lock.c:1747
@ LOCKTAG_OBJECT
Definition: lock.h:150
@ LOCKACQUIRE_ALREADY_CLEAR
Definition: lock.h:497
@ LOCKACQUIRE_OK
Definition: lock.h:495
@ LOCKACQUIRE_ALREADY_HELD
Definition: lock.h:496
@ LOCKACQUIRE_NOT_AVAIL
Definition: lock.h:494
#define RowExclusiveLock
Definition: lockdefs.h:38
ResourceOwner CurrentResourceOwner
Definition: resowner.c:146
void LogAccessExclusiveLockPrepare(void)
Definition: standby.c:1377
void LogAccessExclusiveLock(Oid dbOid, Oid relOid)
Definition: standby.c:1360
bool lockCleared
Definition: lock.h:432
uint16 locktag_field4
Definition: lock.h:172
LOCKMASK heldLocks
Definition: proc.h:220
bool RecoveryInProgress(void)
Definition: xlog.c:5762
#define XLogStandbyInfoActive()
Definition: xlog.h:118
bool InRecovery
Definition: xlogutils.c:53

References AbortStrongLockAcquire(), AccessExclusiveLock, Assert(), BeginStrongLockAcquire(), ConflictsWithRelationFastPath, LockMethodData::conflictTab, FastPathStrongRelationLockData::count, CurrentResourceOwner, EligibleForRelationFastPath, elog, ereport, errcode(), errhint(), errmsg(), ERROR, FastPathGrantRelationLock(), FastPathLocalUseCount, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, FastPathTransferRelationLocks(), FinishStrongLockAcquire(), FP_LOCK_SLOTS_PER_BACKEND, PGPROC::fpInfoLock, GrantLock(), GrantLockLocal(), HASH_ENTER, HASH_REMOVE, hash_search(), hash_search_with_hash_value(), LOCALLOCK::hashcode, PGPROC::heldLocks, PROCLOCK::holdMask, LOCALLOCK::holdsStrongLockCount, InRecovery, lengthof, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_PRINT, LOCKACQUIRE_ALREADY_CLEAR, LOCKACQUIRE_ALREADY_HELD, LOCKACQUIRE_NOT_AVAIL, LOCKACQUIRE_OK, LOCKBIT_ON, LockCheckConflicts(), LOCALLOCK::lockCleared, LockHashPartitionLock, PROCLOCK::lockLink, LockMethodLocalHash, LockMethodProcLockHash, LockMethods, LockMethodData::lockModeNames, LOCALLOCK::lockOwners, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_field3, LOCKTAG::locktag_field4, LOCKTAG::locktag_lockmethodid, LOCKTAG_OBJECT, LOCKTAG_RELATION, LOCKTAG_RELATION_EXTEND, LOCKTAG::locktag_type, LockTagHashCode(), LOG, LogAccessExclusiveLock(), LogAccessExclusiveLockPrepare(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), LOCALLOCK::maxLockOwners, MemoryContextAlloc(), MemSet, LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, LOCK::nGranted, LOCALLOCK::nLocks, LOCK::nRequested, LockMethodData::numLockModes, LOCALLOCK::numLockOwners, PANIC, PROCLOCK::procLink, LOCALLOCK::proclock, PROCLOCK_PRINT, ProcLockHashCode(), RecoveryInProgress(), RemoveLocalLock(), repalloc(), LOCK::requested, RowExclusiveLock, SetupLockInTable(), SHMQueueDelete(), PROCLOCK::tag, TopMemoryContext, LOCK::waitMask, WaitOnLock(), and XLogStandbyInfoActive.

Referenced by ConditionalLockRelation(), ConditionalLockRelationOid(), LockAcquire(), LockRelation(), LockRelationId(), and LockRelationOid().

◆ LockCheckConflicts()

bool LockCheckConflicts ( LockMethod  lockMethodTable,
LOCKMODE  lockmode,
LOCK lock,
PROCLOCK proclock 
)

Definition at line 1420 of file lock.c.

1424 {
1425  int numLockModes = lockMethodTable->numLockModes;
1426  LOCKMASK myLocks;
1427  int conflictMask = lockMethodTable->conflictTab[lockmode];
1428  int conflictsRemaining[MAX_LOCKMODES];
1429  int totalConflictsRemaining = 0;
1430  int i;
1431  SHM_QUEUE *procLocks;
1432  PROCLOCK *otherproclock;
1433 
1434  /*
1435  * first check for global conflicts: If no locks conflict with my request,
1436  * then I get the lock.
1437  *
1438  * Checking for conflict: lock->grantMask represents the types of
1439  * currently held locks. conflictTable[lockmode] has a bit set for each
1440  * type of lock that conflicts with request. Bitwise compare tells if
1441  * there is a conflict.
1442  */
1443  if (!(conflictMask & lock->grantMask))
1444  {
1445  PROCLOCK_PRINT("LockCheckConflicts: no conflict", proclock);
1446  return false;
1447  }
1448 
1449  /*
1450  * Rats. Something conflicts. But it could still be my own lock, or a
1451  * lock held by another member of my locking group. First, figure out how
1452  * many conflicts remain after subtracting out any locks I hold myself.
1453  */
1454  myLocks = proclock->holdMask;
1455  for (i = 1; i <= numLockModes; i++)
1456  {
1457  if ((conflictMask & LOCKBIT_ON(i)) == 0)
1458  {
1459  conflictsRemaining[i] = 0;
1460  continue;
1461  }
1462  conflictsRemaining[i] = lock->granted[i];
1463  if (myLocks & LOCKBIT_ON(i))
1464  --conflictsRemaining[i];
1465  totalConflictsRemaining += conflictsRemaining[i];
1466  }
1467 
1468  /* If no conflicts remain, we get the lock. */
1469  if (totalConflictsRemaining == 0)
1470  {
1471  PROCLOCK_PRINT("LockCheckConflicts: resolved (simple)", proclock);
1472  return false;
1473  }
1474 
1475  /* If no group locking, it's definitely a conflict. */
1476  if (proclock->groupLeader == MyProc && MyProc->lockGroupLeader == NULL)
1477  {
1478  Assert(proclock->tag.myProc == MyProc);
1479  PROCLOCK_PRINT("LockCheckConflicts: conflicting (simple)",
1480  proclock);
1481  return true;
1482  }
1483 
1484  /*
1485  * The relation extension or page lock conflict even between the group
1486  * members.
1487  */
1488  if (LOCK_LOCKTAG(*lock) == LOCKTAG_RELATION_EXTEND ||
1489  (LOCK_LOCKTAG(*lock) == LOCKTAG_PAGE))
1490  {
1491  PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)",
1492  proclock);
1493  return true;
1494  }
1495 
1496  /*
1497  * Locks held in conflicting modes by members of our own lock group are
1498  * not real conflicts; we can subtract those out and see if we still have
1499  * a conflict. This is O(N) in the number of processes holding or
1500  * awaiting locks on this object. We could improve that by making the
1501  * shared memory state more complex (and larger) but it doesn't seem worth
1502  * it.
1503  */
1504  procLocks = &(lock->procLocks);
1505  otherproclock = (PROCLOCK *)
1506  SHMQueueNext(procLocks, procLocks, offsetof(PROCLOCK, lockLink));
1507  while (otherproclock != NULL)
1508  {
1509  if (proclock != otherproclock &&
1510  proclock->groupLeader == otherproclock->groupLeader &&
1511  (otherproclock->holdMask & conflictMask) != 0)
1512  {
1513  int intersectMask = otherproclock->holdMask & conflictMask;
1514 
1515  for (i = 1; i <= numLockModes; i++)
1516  {
1517  if ((intersectMask & LOCKBIT_ON(i)) != 0)
1518  {
1519  if (conflictsRemaining[i] <= 0)
1520  elog(PANIC, "proclocks held do not match lock");
1521  conflictsRemaining[i]--;
1522  totalConflictsRemaining--;
1523  }
1524  }
1525 
1526  if (totalConflictsRemaining == 0)
1527  {
1528  PROCLOCK_PRINT("LockCheckConflicts: resolved (group)",
1529  proclock);
1530  return false;
1531  }
1532  }
1533  otherproclock = (PROCLOCK *)
1534  SHMQueueNext(procLocks, &otherproclock->lockLink,
1535  offsetof(PROCLOCK, lockLink));
1536  }
1537 
1538  /* Nope, it's a real conflict. */
1539  PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)", proclock);
1540  return true;
1541 }
#define LOCK_LOCKTAG(lock)
Definition: lock.h:317

References Assert(), LockMethodData::conflictTab, elog, LOCK::granted, LOCK::grantMask, PROCLOCK::groupLeader, PROCLOCK::holdMask, i, LOCK_LOCKTAG, LOCKBIT_ON, PGPROC::lockGroupLeader, PROCLOCK::lockLink, LOCKTAG_PAGE, LOCKTAG_RELATION_EXTEND, MAX_LOCKMODES, MyProc, PROCLOCKTAG::myProc, LockMethodData::numLockModes, offsetof, PANIC, PROCLOCK_PRINT, LOCK::procLocks, SHMQueueNext(), and PROCLOCK::tag.

Referenced by LockAcquireExtended(), ProcLockWakeup(), and ProcSleep().

◆ LockHasWaiters()

bool LockHasWaiters ( const LOCKTAG locktag,
LOCKMODE  lockmode,
bool  sessionLock 
)

Definition at line 634 of file lock.c.

635 {
636  LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
637  LockMethod lockMethodTable;
638  LOCALLOCKTAG localtag;
639  LOCALLOCK *locallock;
640  LOCK *lock;
641  PROCLOCK *proclock;
642  LWLock *partitionLock;
643  bool hasWaiters = false;
644 
645  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
646  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
647  lockMethodTable = LockMethods[lockmethodid];
648  if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
649  elog(ERROR, "unrecognized lock mode: %d", lockmode);
650 
651 #ifdef LOCK_DEBUG
652  if (LOCK_DEBUG_ENABLED(locktag))
653  elog(LOG, "LockHasWaiters: lock [%u,%u] %s",
654  locktag->locktag_field1, locktag->locktag_field2,
655  lockMethodTable->lockModeNames[lockmode]);
656 #endif
657 
658  /*
659  * Find the LOCALLOCK entry for this lock and lockmode
660  */
661  MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
662  localtag.lock = *locktag;
663  localtag.mode = lockmode;
664 
665  locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
666  (void *) &localtag,
667  HASH_FIND, NULL);
668 
669  /*
670  * let the caller print its own error message, too. Do not ereport(ERROR).
671  */
672  if (!locallock || locallock->nLocks <= 0)
673  {
674  elog(WARNING, "you don't own a lock of type %s",
675  lockMethodTable->lockModeNames[lockmode]);
676  return false;
677  }
678 
679  /*
680  * Check the shared lock table.
681  */
682  partitionLock = LockHashPartitionLock(locallock->hashcode);
683 
684  LWLockAcquire(partitionLock, LW_SHARED);
685 
686  /*
687  * We don't need to re-find the lock or proclock, since we kept their
688  * addresses in the locallock table, and they couldn't have been removed
689  * while we were holding a lock on them.
690  */
691  lock = locallock->lock;
692  LOCK_PRINT("LockHasWaiters: found", lock, lockmode);
693  proclock = locallock->proclock;
694  PROCLOCK_PRINT("LockHasWaiters: found", proclock);
695 
696  /*
697  * Double-check that we are actually holding a lock of the type we want to
698  * release.
699  */
700  if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
701  {
702  PROCLOCK_PRINT("LockHasWaiters: WRONGTYPE", proclock);
703  LWLockRelease(partitionLock);
704  elog(WARNING, "you don't own a lock of type %s",
705  lockMethodTable->lockModeNames[lockmode]);
706  RemoveLocalLock(locallock);
707  return false;
708  }
709 
710  /*
711  * Do the checking.
712  */
713  if ((lockMethodTable->conflictTab[lockmode] & lock->waitMask) != 0)
714  hasWaiters = true;
715 
716  LWLockRelease(partitionLock);
717 
718  return hasWaiters;
719 }
#define WARNING
Definition: elog.h:30

References LockMethodData::conflictTab, elog, ERROR, HASH_FIND, hash_search(), LOCALLOCK::hashcode, PROCLOCK::holdMask, lengthof, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_PRINT, LOCKBIT_ON, LockHashPartitionLock, LockMethodLocalHash, LockMethods, LockMethodData::lockModeNames, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LOG, LW_SHARED, LWLockAcquire(), LWLockRelease(), MemSet, LOCALLOCKTAG::mode, LOCALLOCK::nLocks, LockMethodData::numLockModes, LOCALLOCK::proclock, PROCLOCK_PRINT, RemoveLocalLock(), LOCK::waitMask, and WARNING.

Referenced by LockHasWaitersRelation().

◆ LockHeldByMe()

bool LockHeldByMe ( const LOCKTAG locktag,
LOCKMODE  lockmode 
)

Definition at line 598 of file lock.c.

599 {
600  LOCALLOCKTAG localtag;
601  LOCALLOCK *locallock;
602 
603  /*
604  * See if there is a LOCALLOCK entry for this lock and lockmode
605  */
606  MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
607  localtag.lock = *locktag;
608  localtag.mode = lockmode;
609 
610  locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
611  (void *) &localtag,
612  HASH_FIND, NULL);
613 
614  return (locallock && locallock->nLocks > 0);
615 }

References HASH_FIND, hash_search(), LOCALLOCKTAG::lock, LockMethodLocalHash, MemSet, LOCALLOCKTAG::mode, and LOCALLOCK::nLocks.

Referenced by CheckRelationLockedByMe().

◆ LockReassignCurrentOwner()

void LockReassignCurrentOwner ( LOCALLOCK **  locallocks,
int  nlocks 
)

Definition at line 2579 of file lock.c.

2580 {
2582 
2583  Assert(parent != NULL);
2584 
2585  if (locallocks == NULL)
2586  {
2588  LOCALLOCK *locallock;
2589 
2591 
2592  while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
2593  LockReassignOwner(locallock, parent);
2594  }
2595  else
2596  {
2597  int i;
2598 
2599  for (i = nlocks - 1; i >= 0; i--)
2600  LockReassignOwner(locallocks[i], parent);
2601  }
2602 }
static void LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent)
Definition: lock.c:2609
ResourceOwner ResourceOwnerGetParent(ResourceOwner owner)
Definition: resowner.c:792

References Assert(), CurrentResourceOwner, hash_seq_init(), hash_seq_search(), i, LockMethodLocalHash, LockReassignOwner(), ResourceOwnerGetParent(), and status().

Referenced by ResourceOwnerReleaseInternal().

◆ LockReassignOwner()

static void LockReassignOwner ( LOCALLOCK locallock,
ResourceOwner  parent 
)
static

Definition at line 2609 of file lock.c.

2610 {
2611  LOCALLOCKOWNER *lockOwners;
2612  int i;
2613  int ic = -1;
2614  int ip = -1;
2615 
2616  /*
2617  * Scan to see if there are any locks belonging to current owner or its
2618  * parent
2619  */
2620  lockOwners = locallock->lockOwners;
2621  for (i = locallock->numLockOwners - 1; i >= 0; i--)
2622  {
2623  if (lockOwners[i].owner == CurrentResourceOwner)
2624  ic = i;
2625  else if (lockOwners[i].owner == parent)
2626  ip = i;
2627  }
2628 
2629  if (ic < 0)
2630  return; /* no current locks */
2631 
2632  if (ip < 0)
2633  {
2634  /* Parent has no slot, so just give it the child's slot */
2635  lockOwners[ic].owner = parent;
2636  ResourceOwnerRememberLock(parent, locallock);
2637  }
2638  else
2639  {
2640  /* Merge child's count with parent's */
2641  lockOwners[ip].nLocks += lockOwners[ic].nLocks;
2642  /* compact out unused slot */
2643  locallock->numLockOwners--;
2644  if (ic < locallock->numLockOwners)
2645  lockOwners[ic] = lockOwners[locallock->numLockOwners];
2646  }
2648 }
void ResourceOwnerForgetLock(ResourceOwner owner, LOCALLOCK *locallock)
Definition: resowner.c:1005

References CurrentResourceOwner, i, LOCALLOCK::lockOwners, LOCALLOCKOWNER::nLocks, LOCALLOCK::numLockOwners, LOCALLOCKOWNER::owner, ResourceOwnerForgetLock(), and ResourceOwnerRememberLock().

Referenced by LockReassignCurrentOwner().

◆ LockRefindAndRelease()

static void LockRefindAndRelease ( LockMethod  lockMethodTable,
PGPROC proc,
LOCKTAG locktag,
LOCKMODE  lockmode,
bool  decrement_strong_lock_count 
)
static

Definition at line 3129 of file lock.c.

3132 {
3133  LOCK *lock;
3134  PROCLOCK *proclock;
3135  PROCLOCKTAG proclocktag;
3136  uint32 hashcode;
3137  uint32 proclock_hashcode;
3138  LWLock *partitionLock;
3139  bool wakeupNeeded;
3140 
3141  hashcode = LockTagHashCode(locktag);
3142  partitionLock = LockHashPartitionLock(hashcode);
3143 
3144  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
3145 
3146  /*
3147  * Re-find the lock object (it had better be there).
3148  */
3150  (void *) locktag,
3151  hashcode,
3152  HASH_FIND,
3153  NULL);
3154  if (!lock)
3155  elog(PANIC, "failed to re-find shared lock object");
3156 
3157  /*
3158  * Re-find the proclock object (ditto).
3159  */
3160  proclocktag.myLock = lock;
3161  proclocktag.myProc = proc;
3162 
3163  proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
3164 
3166  (void *) &proclocktag,
3167  proclock_hashcode,
3168  HASH_FIND,
3169  NULL);
3170  if (!proclock)
3171  elog(PANIC, "failed to re-find shared proclock object");
3172 
3173  /*
3174  * Double-check that we are actually holding a lock of the type we want to
3175  * release.
3176  */
3177  if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
3178  {
3179  PROCLOCK_PRINT("lock_twophase_postcommit: WRONGTYPE", proclock);
3180  LWLockRelease(partitionLock);
3181  elog(WARNING, "you don't own a lock of type %s",
3182  lockMethodTable->lockModeNames[lockmode]);
3183  return;
3184  }
3185 
3186  /*
3187  * Do the releasing. CleanUpLock will waken any now-wakable waiters.
3188  */
3189  wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
3190 
3191  CleanUpLock(lock, proclock,
3192  lockMethodTable, hashcode,
3193  wakeupNeeded);
3194 
3195  LWLockRelease(partitionLock);
3196 
3197  /*
3198  * Decrement strong lock count. This logic is needed only for 2PC.
3199  */
3200  if (decrement_strong_lock_count
3201  && ConflictsWithRelationFastPath(locktag, lockmode))
3202  {
3203  uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
3204 
3206  Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
3207  FastPathStrongRelationLocks->count[fasthashcode]--;
3209  }
3210 }
static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode, PROCLOCK *proclock, LockMethod lockMethodTable)
Definition: lock.c:1578
static void CleanUpLock(LOCK *lock, PROCLOCK *proclock, LockMethod lockMethodTable, uint32 hashcode, bool wakeupNeeded)
Definition: lock.c:1635

References Assert(), CleanUpLock(), ConflictsWithRelationFastPath, FastPathStrongRelationLockData::count, elog, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, HASH_FIND, hash_search_with_hash_value(), PROCLOCK::holdMask, LOCKBIT_ON, LockHashPartitionLock, LockMethodLockHash, LockMethodProcLockHash, LockMethodData::lockModeNames, LockTagHashCode(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), FastPathStrongRelationLockData::mutex, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, PANIC, PROCLOCK_PRINT, ProcLockHashCode(), SpinLockAcquire, SpinLockRelease, UnGrantLock(), and WARNING.

Referenced by lock_twophase_postcommit(), LockReleaseAll(), and VirtualXactLockTableCleanup().

◆ LockRelease()

bool LockRelease ( const LOCKTAG locktag,
LOCKMODE  lockmode,
bool  sessionLock 
)

Definition at line 1975 of file lock.c.

1976 {
1977  LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
1978  LockMethod lockMethodTable;
1979  LOCALLOCKTAG localtag;
1980  LOCALLOCK *locallock;
1981  LOCK *lock;
1982  PROCLOCK *proclock;
1983  LWLock *partitionLock;
1984  bool wakeupNeeded;
1985 
1986  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
1987  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
1988  lockMethodTable = LockMethods[lockmethodid];
1989  if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
1990  elog(ERROR, "unrecognized lock mode: %d", lockmode);
1991 
1992 #ifdef LOCK_DEBUG
1993  if (LOCK_DEBUG_ENABLED(locktag))
1994  elog(LOG, "LockRelease: lock [%u,%u] %s",
1995  locktag->locktag_field1, locktag->locktag_field2,
1996  lockMethodTable->lockModeNames[lockmode]);
1997 #endif
1998 
1999  /*
2000  * Find the LOCALLOCK entry for this lock and lockmode
2001  */
2002  MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
2003  localtag.lock = *locktag;
2004  localtag.mode = lockmode;
2005 
2006  locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
2007  (void *) &localtag,
2008  HASH_FIND, NULL);
2009 
2010  /*
2011  * let the caller print its own error message, too. Do not ereport(ERROR).
2012  */
2013  if (!locallock || locallock->nLocks <= 0)
2014  {
2015  elog(WARNING, "you don't own a lock of type %s",
2016  lockMethodTable->lockModeNames[lockmode]);
2017  return false;
2018  }
2019 
2020  /*
2021  * Decrease the count for the resource owner.
2022  */
2023  {
2024  LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
2025  ResourceOwner owner;
2026  int i;
2027 
2028  /* Identify owner for lock */
2029  if (sessionLock)
2030  owner = NULL;
2031  else
2032  owner = CurrentResourceOwner;
2033 
2034  for (i = locallock->numLockOwners - 1; i >= 0; i--)
2035  {
2036  if (lockOwners[i].owner == owner)
2037  {
2038  Assert(lockOwners[i].nLocks > 0);
2039  if (--lockOwners[i].nLocks == 0)
2040  {
2041  if (owner != NULL)
2042  ResourceOwnerForgetLock(owner, locallock);
2043  /* compact out unused slot */
2044  locallock->numLockOwners--;
2045  if (i < locallock->numLockOwners)
2046  lockOwners[i] = lockOwners[locallock->numLockOwners];
2047  }
2048  break;
2049  }
2050  }
2051  if (i < 0)
2052  {
2053  /* don't release a lock belonging to another owner */
2054  elog(WARNING, "you don't own a lock of type %s",
2055  lockMethodTable->lockModeNames[lockmode]);
2056  return false;
2057  }
2058  }
2059 
2060  /*
2061  * Decrease the total local count. If we're still holding the lock, we're
2062  * done.
2063  */
2064  locallock->nLocks--;
2065 
2066  if (locallock->nLocks > 0)
2067  return true;
2068 
2069  /*
2070  * At this point we can no longer suppose we are clear of invalidation
2071  * messages related to this lock. Although we'll delete the LOCALLOCK
2072  * object before any intentional return from this routine, it seems worth
2073  * the trouble to explicitly reset lockCleared right now, just in case
2074  * some error prevents us from deleting the LOCALLOCK.
2075  */
2076  locallock->lockCleared = false;
2077 
2078  /* Attempt fast release of any lock eligible for the fast path. */
2079  if (EligibleForRelationFastPath(locktag, lockmode) &&
2081  {
2082  bool released;
2083 
2084  /*
2085  * We might not find the lock here, even if we originally entered it
2086  * here. Another backend may have moved it to the main table.
2087  */
2089  released = FastPathUnGrantRelationLock(locktag->locktag_field2,
2090  lockmode);
2092  if (released)
2093  {
2094  RemoveLocalLock(locallock);
2095  return true;
2096  }
2097  }
2098 
2099  /*
2100  * Otherwise we've got to mess with the shared lock table.
2101  */
2102  partitionLock = LockHashPartitionLock(locallock->hashcode);
2103 
2104  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
2105 
2106  /*
2107  * Normally, we don't need to re-find the lock or proclock, since we kept
2108  * their addresses in the locallock table, and they couldn't have been
2109  * removed while we were holding a lock on them. But it's possible that
2110  * the lock was taken fast-path and has since been moved to the main hash
2111  * table by another backend, in which case we will need to look up the
2112  * objects here. We assume the lock field is NULL if so.
2113  */
2114  lock = locallock->lock;
2115  if (!lock)
2116  {
2117  PROCLOCKTAG proclocktag;
2118 
2119  Assert(EligibleForRelationFastPath(locktag, lockmode));
2121  (const void *) locktag,
2122  locallock->hashcode,
2123  HASH_FIND,
2124  NULL);
2125  if (!lock)
2126  elog(ERROR, "failed to re-find shared lock object");
2127  locallock->lock = lock;
2128 
2129  proclocktag.myLock = lock;
2130  proclocktag.myProc = MyProc;
2132  (void *) &proclocktag,
2133  HASH_FIND,
2134  NULL);
2135  if (!locallock->proclock)
2136  elog(ERROR, "failed to re-find shared proclock object");
2137  }
2138  LOCK_PRINT("LockRelease: found", lock, lockmode);
2139  proclock = locallock->proclock;
2140  PROCLOCK_PRINT("LockRelease: found", proclock);
2141 
2142  /*
2143  * Double-check that we are actually holding a lock of the type we want to
2144  * release.
2145  */
2146  if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
2147  {
2148  PROCLOCK_PRINT("LockRelease: WRONGTYPE", proclock);
2149  LWLockRelease(partitionLock);
2150  elog(WARNING, "you don't own a lock of type %s",
2151  lockMethodTable->lockModeNames[lockmode]);
2152  RemoveLocalLock(locallock);
2153  return false;
2154  }
2155 
2156  /*
2157  * Do the releasing. CleanUpLock will waken any now-wakable waiters.
2158  */
2159  wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
2160 
2161  CleanUpLock(lock, proclock,
2162  lockMethodTable, locallock->hashcode,
2163  wakeupNeeded);
2164 
2165  LWLockRelease(partitionLock);
2166 
2167  RemoveLocalLock(locallock);
2168  return true;
2169 }
static bool FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode)
Definition: lock.c:2692

References Assert(), CleanUpLock(), CurrentResourceOwner, EligibleForRelationFastPath, elog, ERROR, FastPathLocalUseCount, FastPathUnGrantRelationLock(), PGPROC::fpInfoLock, HASH_FIND, hash_search(), hash_search_with_hash_value(), LOCALLOCK::hashcode, PROCLOCK::holdMask, i, lengthof, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_PRINT, LOCKBIT_ON, LOCALLOCK::lockCleared, LockHashPartitionLock, LockMethodLocalHash, LockMethodLockHash, LockMethodProcLockHash, LockMethods, LockMethodData::lockModeNames, LOCALLOCK::lockOwners, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LOG, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MemSet, LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, PROCLOCKTAG::myProc, LOCALLOCK::nLocks, LockMethodData::numLockModes, LOCALLOCK::numLockOwners, LOCALLOCK::proclock, PROCLOCK_PRINT, RemoveLocalLock(), ResourceOwnerForgetLock(), UnGrantLock(), and WARNING.

Referenced by ConditionalXactLockTableWait(), pg_advisory_unlock_int4(), pg_advisory_unlock_int8(), pg_advisory_unlock_shared_int4(), pg_advisory_unlock_shared_int8(), ReleaseLockIfHeld(), SpeculativeInsertionLockRelease(), SpeculativeInsertionWait(), StandbyReleaseLockList(), UnlockDatabaseObject(), UnlockPage(), UnlockRelation(), UnlockRelationForExtension(), UnlockRelationId(), UnlockRelationIdForSession(), UnlockRelationOid(), UnlockSharedObject(), UnlockSharedObjectForSession(), UnlockTuple(), VirtualXactLock(), XactLockForVirtualXact(), XactLockTableDelete(), and XactLockTableWait().

◆ LockReleaseAll()

void LockReleaseAll ( LOCKMETHODID  lockmethodid,
bool  allLocks 
)

Definition at line 2180 of file lock.c.

2181 {
2183  LockMethod lockMethodTable;
2184  int i,
2185  numLockModes;
2186  LOCALLOCK *locallock;
2187  LOCK *lock;
2188  PROCLOCK *proclock;
2189  int partition;
2190  bool have_fast_path_lwlock = false;
2191 
2192  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
2193  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
2194  lockMethodTable = LockMethods[lockmethodid];
2195 
2196 #ifdef LOCK_DEBUG
2197  if (*(lockMethodTable->trace_flag))
2198  elog(LOG, "LockReleaseAll: lockmethod=%d", lockmethodid);
2199 #endif
2200 
2201  /*
2202  * Get rid of our fast-path VXID lock, if appropriate. Note that this is
2203  * the only way that the lock we hold on our own VXID can ever get
2204  * released: it is always and only released when a toplevel transaction
2205  * ends.
2206  */
2207  if (lockmethodid == DEFAULT_LOCKMETHOD)
2209 
2210  numLockModes = lockMethodTable->numLockModes;
2211 
2212  /*
2213  * First we run through the locallock table and get rid of unwanted
2214  * entries, then we scan the process's proclocks and get rid of those. We
2215  * do this separately because we may have multiple locallock entries
2216  * pointing to the same proclock, and we daren't end up with any dangling
2217  * pointers. Fast-path locks are cleaned up during the locallock table
2218  * scan, though.
2219  */
2221 
2222  while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
2223  {
2224  /*
2225  * If the LOCALLOCK entry is unused, we must've run out of shared
2226  * memory while trying to set up this lock. Just forget the local
2227  * entry.
2228  */
2229  if (locallock->nLocks == 0)
2230  {
2231  RemoveLocalLock(locallock);
2232  continue;
2233  }
2234 
2235  /* Ignore items that are not of the lockmethod to be removed */
2236  if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
2237  continue;
2238 
2239  /*
2240  * If we are asked to release all locks, we can just zap the entry.
2241  * Otherwise, must scan to see if there are session locks. We assume
2242  * there is at most one lockOwners entry for session locks.
2243  */
2244  if (!allLocks)
2245  {
2246  LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
2247 
2248  /* If session lock is above array position 0, move it down to 0 */
2249  for (i = 0; i < locallock->numLockOwners; i++)
2250  {
2251  if (lockOwners[i].owner == NULL)
2252  lockOwners[0] = lockOwners[i];
2253  else
2254  ResourceOwnerForgetLock(lockOwners[i].owner, locallock);
2255  }
2256 
2257  if (locallock->numLockOwners > 0 &&
2258  lockOwners[0].owner == NULL &&
2259  lockOwners[0].nLocks > 0)
2260  {
2261  /* Fix the locallock to show just the session locks */
2262  locallock->nLocks = lockOwners[0].nLocks;
2263  locallock->numLockOwners = 1;
2264  /* We aren't deleting this locallock, so done */
2265  continue;
2266  }
2267  else
2268  locallock->numLockOwners = 0;
2269  }
2270 
2271  /*
2272  * If the lock or proclock pointers are NULL, this lock was taken via
2273  * the relation fast-path (and is not known to have been transferred).
2274  */
2275  if (locallock->proclock == NULL || locallock->lock == NULL)
2276  {
2277  LOCKMODE lockmode = locallock->tag.mode;
2278  Oid relid;
2279 
2280  /* Verify that a fast-path lock is what we've got. */
2281  if (!EligibleForRelationFastPath(&locallock->tag.lock, lockmode))
2282  elog(PANIC, "locallock table corrupted");
2283 
2284  /*
2285  * If we don't currently hold the LWLock that protects our
2286  * fast-path data structures, we must acquire it before attempting
2287  * to release the lock via the fast-path. We will continue to
2288  * hold the LWLock until we're done scanning the locallock table,
2289  * unless we hit a transferred fast-path lock. (XXX is this
2290  * really such a good idea? There could be a lot of entries ...)
2291  */
2292  if (!have_fast_path_lwlock)
2293  {
2295  have_fast_path_lwlock = true;
2296  }
2297 
2298  /* Attempt fast-path release. */
2299  relid = locallock->tag.lock.locktag_field2;
2300  if (FastPathUnGrantRelationLock(relid, lockmode))
2301  {
2302  RemoveLocalLock(locallock);
2303  continue;
2304  }
2305 
2306  /*
2307  * Our lock, originally taken via the fast path, has been
2308  * transferred to the main lock table. That's going to require
2309  * some extra work, so release our fast-path lock before starting.
2310  */
2312  have_fast_path_lwlock = false;
2313 
2314  /*
2315  * Now dump the lock. We haven't got a pointer to the LOCK or
2316  * PROCLOCK in this case, so we have to handle this a bit
2317  * differently than a normal lock release. Unfortunately, this
2318  * requires an extra LWLock acquire-and-release cycle on the
2319  * partitionLock, but hopefully it shouldn't happen often.
2320  */
2321  LockRefindAndRelease(lockMethodTable, MyProc,
2322  &locallock->tag.lock, lockmode, false);
2323  RemoveLocalLock(locallock);
2324  continue;
2325  }
2326 
2327  /* Mark the proclock to show we need to release this lockmode */
2328  if (locallock->nLocks > 0)
2329  locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
2330 
2331  /* And remove the locallock hashtable entry */
2332  RemoveLocalLock(locallock);
2333  }
2334 
2335  /* Done with the fast-path data structures */
2336  if (have_fast_path_lwlock)
2338 
2339  /*
2340  * Now, scan each lock partition separately.
2341  */
2342  for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
2343  {
2344  LWLock *partitionLock;
2345  SHM_QUEUE *procLocks = &(MyProc->myProcLocks[partition]);
2346  PROCLOCK *nextplock;
2347 
2348  partitionLock = LockHashPartitionLockByIndex(partition);
2349 
2350  /*
2351  * If the proclock list for this partition is empty, we can skip
2352  * acquiring the partition lock. This optimization is trickier than
2353  * it looks, because another backend could be in process of adding
2354  * something to our proclock list due to promoting one of our
2355  * fast-path locks. However, any such lock must be one that we
2356  * decided not to delete above, so it's okay to skip it again now;
2357  * we'd just decide not to delete it again. We must, however, be
2358  * careful to re-fetch the list header once we've acquired the
2359  * partition lock, to be sure we have a valid, up-to-date pointer.
2360  * (There is probably no significant risk if pointer fetch/store is
2361  * atomic, but we don't wish to assume that.)
2362  *
2363  * XXX This argument assumes that the locallock table correctly
2364  * represents all of our fast-path locks. While allLocks mode
2365  * guarantees to clean up all of our normal locks regardless of the
2366  * locallock situation, we lose that guarantee for fast-path locks.
2367  * This is not ideal.
2368  */
2369  if (SHMQueueNext(procLocks, procLocks,
2370  offsetof(PROCLOCK, procLink)) == NULL)
2371  continue; /* needn't examine this partition */
2372 
2373  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
2374 
2375  for (proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
2376  offsetof(PROCLOCK, procLink));
2377  proclock;
2378  proclock = nextplock)
2379  {
2380  bool wakeupNeeded = false;
2381 
2382  /* Get link first, since we may unlink/delete this proclock */
2383  nextplock = (PROCLOCK *)
2384  SHMQueueNext(procLocks, &proclock->procLink,
2385  offsetof(PROCLOCK, procLink));
2386 
2387  Assert(proclock->tag.myProc == MyProc);
2388 
2389  lock = proclock->tag.myLock;
2390 
2391  /* Ignore items that are not of the lockmethod to be removed */
2392  if (LOCK_LOCKMETHOD(*lock) != lockmethodid)
2393  continue;
2394 
2395  /*
2396  * In allLocks mode, force release of all locks even if locallock
2397  * table had problems
2398  */
2399  if (allLocks)
2400  proclock->releaseMask = proclock->holdMask;
2401  else
2402  Assert((proclock->releaseMask & ~proclock->holdMask) == 0);
2403 
2404  /*
2405  * Ignore items that have nothing to be released, unless they have
2406  * holdMask == 0 and are therefore recyclable
2407  */
2408  if (proclock->releaseMask == 0 && proclock->holdMask != 0)
2409  continue;
2410 
2411  PROCLOCK_PRINT("LockReleaseAll", proclock);
2412  LOCK_PRINT("LockReleaseAll", lock, 0);
2413  Assert(lock->nRequested >= 0);
2414  Assert(lock->nGranted >= 0);
2415  Assert(lock->nGranted <= lock->nRequested);
2416  Assert((proclock->holdMask & ~lock->grantMask) == 0);
2417 
2418  /*
2419  * Release the previously-marked lock modes
2420  */
2421  for (i = 1; i <= numLockModes; i++)
2422  {
2423  if (proclock->releaseMask & LOCKBIT_ON(i))
2424  wakeupNeeded |= UnGrantLock(lock, i, proclock,
2425  lockMethodTable);
2426  }
2427  Assert((lock->nRequested >= 0) && (lock->nGranted >= 0));
2428  Assert(lock->nGranted <= lock->nRequested);
2429  LOCK_PRINT("LockReleaseAll: updated", lock, 0);
2430 
2431  proclock->releaseMask = 0;
2432 
2433  /* CleanUpLock will wake up waiters if needed. */
2434  CleanUpLock(lock, proclock,
2435  lockMethodTable,
2436  LockTagHashCode(&lock->tag),
2437  wakeupNeeded);
2438  } /* loop over PROCLOCKs within this partition */
2439 
2440  LWLockRelease(partitionLock);
2441  } /* loop over partitions */
2442 
2443 #ifdef LOCK_DEBUG
2444  if (*(lockMethodTable->trace_flag))
2445  elog(LOG, "LockReleaseAll done");
2446 #endif
2447 }
void VirtualXactLockTableCleanup(void)
Definition: lock.c:4499
#define LOCALLOCK_LOCKMETHOD(llock)
Definition: lock.h:435
const bool * trace_flag
Definition: lock.h:118

References Assert(), CleanUpLock(), DEFAULT_LOCKMETHOD, EligibleForRelationFastPath, elog, ERROR, FastPathUnGrantRelationLock(), PGPROC::fpInfoLock, LOCK::grantMask, hash_seq_init(), hash_seq_search(), PROCLOCK::holdMask, i, lengthof, LOCALLOCK_LOCKMETHOD, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_LOCKMETHOD, LOCK_PRINT, LOCKBIT_ON, LockHashPartitionLockByIndex, LockMethodLocalHash, LockMethods, LOCALLOCK::lockOwners, LockRefindAndRelease(), LOCKTAG::locktag_field2, LockTagHashCode(), LOG, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, PROCLOCKTAG::myProc, PGPROC::myProcLocks, LOCK::nGranted, LOCALLOCKOWNER::nLocks, LOCALLOCK::nLocks, LOCK::nRequested, NUM_LOCK_PARTITIONS, LockMethodData::numLockModes, LOCALLOCK::numLockOwners, offsetof, LOCALLOCKOWNER::owner, PANIC, PROCLOCK::procLink, LOCALLOCK::proclock, PROCLOCK_PRINT, PROCLOCK::releaseMask, RemoveLocalLock(), ResourceOwnerForgetLock(), SHMQueueNext(), status(), LOCK::tag, PROCLOCK::tag, LOCALLOCK::tag, LockMethodData::trace_flag, UnGrantLock(), and VirtualXactLockTableCleanup().

Referenced by DiscardAll(), ProcReleaseLocks(), and ShutdownPostgres().

◆ LockReleaseCurrentOwner()

void LockReleaseCurrentOwner ( LOCALLOCK **  locallocks,
int  nlocks 
)

Definition at line 2484 of file lock.c.

2485 {
2486  if (locallocks == NULL)
2487  {
2489  LOCALLOCK *locallock;
2490 
2492 
2493  while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
2494  ReleaseLockIfHeld(locallock, false);
2495  }
2496  else
2497  {
2498  int i;
2499 
2500  for (i = nlocks - 1; i >= 0; i--)
2501  ReleaseLockIfHeld(locallocks[i], false);
2502  }
2503 }
static void ReleaseLockIfHeld(LOCALLOCK *locallock, bool sessionLock)
Definition: lock.c:2519

References hash_seq_init(), hash_seq_search(), i, LockMethodLocalHash, ReleaseLockIfHeld(), and status().

Referenced by ResourceOwnerReleaseInternal().

◆ LockReleaseSession()

void LockReleaseSession ( LOCKMETHODID  lockmethodid)

Definition at line 2454 of file lock.c.

2455 {
2457  LOCALLOCK *locallock;
2458 
2459  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
2460  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
2461 
2463 
2464  while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
2465  {
2466  /* Ignore items that are not of the specified lock method */
2467  if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
2468  continue;
2469 
2470  ReleaseLockIfHeld(locallock, true);
2471  }
2472 }

References elog, ERROR, hash_seq_init(), hash_seq_search(), lengthof, LOCALLOCK_LOCKMETHOD, LockMethodLocalHash, LockMethods, ReleaseLockIfHeld(), and status().

Referenced by pg_advisory_unlock_all().

◆ LockShmemSize()

Size LockShmemSize ( void  )

Definition at line 3609 of file lock.c.

3610 {
3611  Size size = 0;
3612  long max_table_size;
3613 
3614  /* lock hash table */
3615  max_table_size = NLOCKENTS();
3616  size = add_size(size, hash_estimate_size(max_table_size, sizeof(LOCK)));
3617 
3618  /* proclock hash table */
3619  max_table_size *= 2;
3620  size = add_size(size, hash_estimate_size(max_table_size, sizeof(PROCLOCK)));
3621 
3622  /*
3623  * Since NLOCKENTS is only an estimate, add 10% safety margin.
3624  */
3625  size = add_size(size, size / 10);
3626 
3627  return size;
3628 }
size_t Size
Definition: c.h:551
Size hash_estimate_size(long num_entries, Size entrysize)
Definition: dynahash.c:780
Size add_size(Size s1, Size s2)
Definition: shmem.c:502

References add_size(), hash_estimate_size(), and NLOCKENTS.

Referenced by CalculateShmemSize().

◆ LockTagHashCode()

uint32 LockTagHashCode ( const LOCKTAG locktag)

Definition at line 517 of file lock.c.

518 {
519  return get_hash_value(LockMethodLockHash, (const void *) locktag);
520 }
uint32 get_hash_value(HTAB *hashp, const void *keyPtr)
Definition: dynahash.c:908

References get_hash_value(), and LockMethodLockHash.

Referenced by CheckDeadLock(), GetLockConflicts(), lock_twophase_recover(), LockAcquireExtended(), LockRefindAndRelease(), LockReleaseAll(), LockWaiterCount(), proclock_hash(), and VirtualXactLock().

◆ LockWaiterCount()

int LockWaiterCount ( const LOCKTAG locktag)

Definition at line 4710 of file lock.c.

4711 {
4712  LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
4713  LOCK *lock;
4714  bool found;
4715  uint32 hashcode;
4716  LWLock *partitionLock;
4717  int waiters = 0;
4718 
4719  if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
4720  elog(ERROR, "unrecognized lock method: %d", lockmethodid);
4721 
4722  hashcode = LockTagHashCode(locktag);
4723  partitionLock = LockHashPartitionLock(hashcode);
4724  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
4725 
4727  (const void *) locktag,
4728  hashcode,
4729  HASH_FIND,
4730  &found);
4731  if (found)
4732  {
4733  Assert(lock != NULL);
4734  waiters = lock->nRequested;
4735  }
4736  LWLockRelease(partitionLock);
4737 
4738  return waiters;
4739 }

References Assert(), elog, ERROR, HASH_FIND, hash_search_with_hash_value(), lengthof, LockHashPartitionLock, LockMethodLockHash, LockMethods, LOCKTAG::locktag_lockmethodid, LockTagHashCode(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), and LOCK::nRequested.

Referenced by RelationExtensionLockWaiterCount().

◆ MarkLockClear()

void MarkLockClear ( LOCALLOCK locallock)

Definition at line 1799 of file lock.c.

1800 {
1801  Assert(locallock->nLocks > 0);
1802  locallock->lockCleared = true;
1803 }

References Assert(), LOCALLOCK::lockCleared, and LOCALLOCK::nLocks.

Referenced by ConditionalLockRelation(), ConditionalLockRelationOid(), LockRelation(), LockRelationId(), and LockRelationOid().

◆ PostPrepare_Locks()

void PostPrepare_Locks ( TransactionId  xid)

Definition at line 3417 of file lock.c.

3418 {
3419  PGPROC *newproc = TwoPhaseGetDummyProc(xid, false);
3421  LOCALLOCK *locallock;
3422  LOCK *lock;
3423  PROCLOCK *proclock;
3424  PROCLOCKTAG proclocktag;
3425  int partition;
3426 
3427  /* Can't prepare a lock group follower. */
3428  Assert(MyProc->lockGroupLeader == NULL ||
3430 
3431  /* This is a critical section: any error means big trouble */
3433 
3434  /*
3435  * First we run through the locallock table and get rid of unwanted
3436  * entries, then we scan the process's proclocks and transfer them to the
3437  * target proc.
3438  *
3439  * We do this separately because we may have multiple locallock entries
3440  * pointing to the same proclock, and we daren't end up with any dangling
3441  * pointers.
3442  */
3444 
3445  while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
3446  {
3447  LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
3448  bool haveSessionLock;
3449  bool haveXactLock;
3450  int i;
3451 
3452  if (locallock->proclock == NULL || locallock->lock == NULL)
3453  {
3454  /*
3455  * We must've run out of shared memory while trying to set up this
3456  * lock. Just forget the local entry.
3457  */
3458  Assert(locallock->nLocks == 0);
3459  RemoveLocalLock(locallock);
3460  continue;
3461  }
3462 
3463  /* Ignore VXID locks */
3464  if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
3465  continue;
3466 
3467  /* Scan to see whether we hold it at session or transaction level */
3468  haveSessionLock = haveXactLock = false;
3469  for (i = locallock->numLockOwners - 1; i >= 0; i--)
3470  {
3471  if (lockOwners[i].owner == NULL)
3472  haveSessionLock = true;
3473  else
3474  haveXactLock = true;
3475  }
3476 
3477  /* Ignore it if we have only session lock */
3478  if (!haveXactLock)
3479  continue;
3480 
3481  /* This can't happen, because we already checked it */
3482  if (haveSessionLock)
3483  ereport(PANIC,
3484  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
3485  errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
3486 
3487  /* Mark the proclock to show we need to release this lockmode */
3488  if (locallock->nLocks > 0)
3489  locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
3490 
3491  /* And remove the locallock hashtable entry */
3492  RemoveLocalLock(locallock);
3493  }
3494 
3495  /*
3496  * Now, scan each lock partition separately.
3497  */
3498  for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
3499  {
3500  LWLock *partitionLock;
3501  SHM_QUEUE *procLocks = &(MyProc->myProcLocks[partition]);
3502  PROCLOCK *nextplock;
3503 
3504  partitionLock = LockHashPartitionLockByIndex(partition);
3505 
3506  /*
3507  * If the proclock list for this partition is empty, we can skip
3508  * acquiring the partition lock. This optimization is safer than the
3509  * situation in LockReleaseAll, because we got rid of any fast-path
3510  * locks during AtPrepare_Locks, so there cannot be any case where
3511  * another backend is adding something to our lists now. For safety,
3512  * though, we code this the same way as in LockReleaseAll.
3513  */
3514  if (SHMQueueNext(procLocks, procLocks,
3515  offsetof(PROCLOCK, procLink)) == NULL)
3516  continue; /* needn't examine this partition */
3517 
3518  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
3519 
3520  for (proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
3521  offsetof(PROCLOCK, procLink));
3522  proclock;
3523  proclock = nextplock)
3524  {
3525  /* Get link first, since we may unlink/relink this proclock */
3526  nextplock = (PROCLOCK *)
3527  SHMQueueNext(procLocks, &proclock->procLink,
3528  offsetof(PROCLOCK, procLink));
3529 
3530  Assert(proclock->tag.myProc == MyProc);
3531 
3532  lock = proclock->tag.myLock;
3533 
3534  /* Ignore VXID locks */
3536  continue;
3537 
3538  PROCLOCK_PRINT("PostPrepare_Locks", proclock);
3539  LOCK_PRINT("PostPrepare_Locks", lock, 0);
3540  Assert(lock->nRequested >= 0);
3541  Assert(lock->nGranted >= 0);
3542  Assert(lock->nGranted <= lock->nRequested);
3543  Assert((proclock->holdMask & ~lock->grantMask) == 0);
3544 
3545  /* Ignore it if nothing to release (must be a session lock) */
3546  if (proclock->releaseMask == 0)
3547  continue;
3548 
3549  /* Else we should be releasing all locks */
3550  if (proclock->releaseMask != proclock->holdMask)
3551  elog(PANIC, "we seem to have dropped a bit somewhere");
3552 
3553  /*
3554  * We cannot simply modify proclock->tag.myProc to reassign
3555  * ownership of the lock, because that's part of the hash key and
3556  * the proclock would then be in the wrong hash chain. Instead
3557  * use hash_update_hash_key. (We used to create a new hash entry,
3558  * but that risks out-of-memory failure if other processes are
3559  * busy making proclocks too.) We must unlink the proclock from
3560  * our procLink chain and put it into the new proc's chain, too.
3561  *
3562  * Note: the updated proclock hash key will still belong to the
3563  * same hash partition, cf proclock_hash(). So the partition lock
3564  * we already hold is sufficient for this.
3565  */
3566  SHMQueueDelete(&proclock->procLink);
3567 
3568  /*
3569  * Create the new hash key for the proclock.
3570  */
3571  proclocktag.myLock = lock;
3572  proclocktag.myProc = newproc;
3573 
3574  /*
3575  * Update groupLeader pointer to point to the new proc. (We'd
3576  * better not be a member of somebody else's lock group!)
3577  */
3578  Assert(proclock->groupLeader == proclock->tag.myProc);
3579  proclock->groupLeader = newproc;
3580 
3581  /*
3582  * Update the proclock. We should not find any existing entry for
3583  * the same hash key, since there can be only one entry for any
3584  * given lock with my own proc.
3585  */
3587  (void *) proclock,
3588  (void *) &proclocktag))
3589  elog(PANIC, "duplicate entry found while reassigning a prepared transaction's locks");
3590 
3591  /* Re-link into the new proc's proclock list */
3592  SHMQueueInsertBefore(&(newproc->myProcLocks[partition]),
3593  &proclock->procLink);
3594 
3595  PROCLOCK_PRINT("PostPrepare_Locks: updated", proclock);
3596  } /* loop over PROCLOCKs within this partition */
3597 
3598  LWLockRelease(partitionLock);
3599  } /* loop over partitions */
3600 
3601  END_CRIT_SECTION();
3602 }
bool hash_update_hash_key(HTAB *hashp, void *existingEntry, const void *newKeyPtr)
Definition: dynahash.c:1162
#define START_CRIT_SECTION()
Definition: miscadmin.h:148
#define END_CRIT_SECTION()
Definition: miscadmin.h:150

References Assert(), elog, END_CRIT_SECTION, ereport, errcode(), errmsg(), LOCK::grantMask, PROCLOCK::groupLeader, hash_seq_init(), hash_seq_search(), hash_update_hash_key(), PROCLOCK::holdMask, i, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_PRINT, LOCKBIT_ON, PGPROC::lockGroupLeader, LockHashPartitionLockByIndex, LockMethodLocalHash, LockMethodProcLockHash, LOCALLOCK::lockOwners, LOCKTAG::locktag_type, LOCKTAG_VIRTUALTRANSACTION, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, PROCLOCKTAG::myProc, PGPROC::myProcLocks, LOCK::nGranted, LOCALLOCK::nLocks, LOCK::nRequested, NUM_LOCK_PARTITIONS, LOCALLOCK::numLockOwners, offsetof, PANIC, PROCLOCK::procLink, LOCALLOCK::proclock, PROCLOCK_PRINT, PROCLOCK::releaseMask, RemoveLocalLock(), SHMQueueDelete(), SHMQueueInsertBefore(), SHMQueueNext(), START_CRIT_SECTION, status(), LOCK::tag, PROCLOCK::tag, LOCALLOCK::tag, and TwoPhaseGetDummyProc().

Referenced by PrepareTransaction().

◆ proclock_hash()

static uint32 proclock_hash ( const void *  key,
Size  keysize 
)
static

Definition at line 534 of file lock.c.

535 {
536  const PROCLOCKTAG *proclocktag = (const PROCLOCKTAG *) key;
537  uint32 lockhash;
538  Datum procptr;
539 
540  Assert(keysize == sizeof(PROCLOCKTAG));
541 
542  /* Look into the associated LOCK object, and compute its hash code */
543  lockhash = LockTagHashCode(&proclocktag->myLock->tag);
544 
545  /*
546  * To make the hash code also depend on the PGPROC, we xor the proc
547  * struct's address into the hash code, left-shifted so that the
548  * partition-number bits don't change. Since this is only a hash, we
549  * don't care if we lose high-order bits of the address; use an
550  * intermediate variable to suppress cast-pointer-to-int warnings.
551  */
552  procptr = PointerGetDatum(proclocktag->myProc);
553  lockhash ^= ((uint32) procptr) << LOG2_NUM_LOCK_PARTITIONS;
554 
555  return lockhash;
556 }
#define LOG2_NUM_LOCK_PARTITIONS
Definition: lwlock.h:86
uintptr_t Datum
Definition: postgres.h:411
#define PointerGetDatum(X)
Definition: postgres.h:600

References Assert(), sort-test::key, LockTagHashCode(), LOG2_NUM_LOCK_PARTITIONS, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, PointerGetDatum, and LOCK::tag.

Referenced by InitLocks().

◆ ProcLockHashCode()

static uint32 ProcLockHashCode ( const PROCLOCKTAG proclocktag,
uint32  hashcode 
)
inlinestatic

Definition at line 565 of file lock.c.

566 {
567  uint32 lockhash = hashcode;
568  Datum procptr;
569 
570  /*
571  * This must match proclock_hash()!
572  */
573  procptr = PointerGetDatum(proclocktag->myProc);
574  lockhash ^= ((uint32) procptr) << LOG2_NUM_LOCK_PARTITIONS;
575 
576  return lockhash;
577 }

References LOG2_NUM_LOCK_PARTITIONS, PROCLOCKTAG::myProc, and PointerGetDatum.

Referenced by CleanUpLock(), FastPathGetRelationLockEntry(), lock_twophase_recover(), LockAcquireExtended(), LockRefindAndRelease(), and SetupLockInTable().

◆ ReleaseLockIfHeld()

static void ReleaseLockIfHeld ( LOCALLOCK locallock,
bool  sessionLock 
)
static

Definition at line 2519 of file lock.c.

2520 {
2521  ResourceOwner owner;
2522  LOCALLOCKOWNER *lockOwners;
2523  int i;
2524 
2525  /* Identify owner for lock (must match LockRelease!) */
2526  if (sessionLock)
2527  owner = NULL;
2528  else
2529  owner = CurrentResourceOwner;
2530 
2531  /* Scan to see if there are any locks belonging to the target owner */
2532  lockOwners = locallock->lockOwners;
2533  for (i = locallock->numLockOwners - 1; i >= 0; i--)
2534  {
2535  if (lockOwners[i].owner == owner)
2536  {
2537  Assert(lockOwners[i].nLocks > 0);
2538  if (lockOwners[i].nLocks < locallock->nLocks)
2539  {
2540  /*
2541  * We will still hold this lock after forgetting this
2542  * ResourceOwner.
2543  */
2544  locallock->nLocks -= lockOwners[i].nLocks;
2545  /* compact out unused slot */
2546  locallock->numLockOwners--;
2547  if (owner != NULL)
2548  ResourceOwnerForgetLock(owner, locallock);
2549  if (i < locallock->numLockOwners)
2550  lockOwners[i] = lockOwners[locallock->numLockOwners];
2551  }
2552  else
2553  {
2554  Assert(lockOwners[i].nLocks == locallock->nLocks);
2555  /* We want to call LockRelease just once */
2556  lockOwners[i].nLocks = 1;
2557  locallock->nLocks = 1;
2558  if (!LockRelease(&locallock->tag.lock,
2559  locallock->tag.mode,
2560  sessionLock))
2561  elog(WARNING, "ReleaseLockIfHeld: failed??");
2562  }
2563  break;
2564  }
2565  }
2566 }
bool LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
Definition: lock.c:1975

References Assert(), CurrentResourceOwner, elog, i, LOCALLOCKTAG::lock, LOCALLOCK::lockOwners, LockRelease(), LOCALLOCKTAG::mode, LOCALLOCKOWNER::nLocks, LOCALLOCK::nLocks, LOCALLOCK::numLockOwners, ResourceOwnerForgetLock(), LOCALLOCK::tag, and WARNING.

Referenced by LockReleaseCurrentOwner(), and LockReleaseSession().

◆ RemoveFromWaitQueue()

void RemoveFromWaitQueue ( PGPROC proc,
uint32  hashcode 
)

Definition at line 1918 of file lock.c.

1919 {
1920  LOCK *waitLock = proc->waitLock;
1921  PROCLOCK *proclock = proc->waitProcLock;
1922  LOCKMODE lockmode = proc->waitLockMode;
1923  LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*waitLock);
1924 
1925  /* Make sure proc is waiting */
1927  Assert(proc->links.next != NULL);
1928  Assert(waitLock);
1929  Assert(waitLock->waitProcs.size > 0);
1930  Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
1931 
1932  /* Remove proc from lock's wait queue */
1933  SHMQueueDelete(&(proc->links));
1934  waitLock->waitProcs.size--;
1935 
1936  /* Undo increments of request counts by waiting process */
1937  Assert(waitLock->nRequested > 0);
1938  Assert(waitLock->nRequested > proc->waitLock->nGranted);
1939  waitLock->nRequested--;
1940  Assert(waitLock->requested[lockmode] > 0);
1941  waitLock->requested[lockmode]--;
1942  /* don't forget to clear waitMask bit if appropriate */
1943  if (waitLock->granted[lockmode] == waitLock->requested[lockmode])
1944  waitLock->waitMask &= LOCKBIT_OFF(lockmode);
1945 
1946  /* Clean up the proc's own state, and pass it the ok/fail signal */
1947  proc->waitLock = NULL;
1948  proc->waitProcLock = NULL;
1950 
1951  /*
1952  * Delete the proclock immediately if it represents no already-held locks.
1953  * (This must happen now because if the owner of the lock decides to
1954  * release it, and the requested/granted counts then go to zero,
1955  * LockRelease expects there to be no remaining proclocks.) Then see if
1956  * any other waiters for the lock can be woken up now.
1957  */
1958  CleanUpLock(waitLock, proclock,
1959  LockMethods[lockmethodid], hashcode,
1960  true);
1961 }
@ PROC_WAIT_STATUS_WAITING
Definition: proc.h:123
@ PROC_WAIT_STATUS_ERROR
Definition: proc.h:124
PROCLOCK * waitProcLock
Definition: proc.h:218
ProcWaitStatus waitStatus
Definition: proc.h:166

References Assert(), CleanUpLock(), LOCK::granted, lengthof, PGPROC::links, LOCK_LOCKMETHOD, LOCKBIT_OFF, LockMethods, SHM_QUEUE::next, LOCK::nGranted, LOCK::nRequested, PROC_WAIT_STATUS_ERROR, PROC_WAIT_STATUS_WAITING, LOCK::requested, SHMQueueDelete(), PROC_QUEUE::size, PGPROC::waitLock, PGPROC::waitLockMode, LOCK::waitMask, PGPROC::waitProcLock, LOCK::waitProcs, and PGPROC::waitStatus.

Referenced by CheckDeadLock(), LockErrorCleanup(), and ProcSleep().

◆ RemoveLocalLock()

static void RemoveLocalLock ( LOCALLOCK locallock)
static

Definition at line 1367 of file lock.c.

1368 {
1369  int i;
1370 
1371  for (i = locallock->numLockOwners - 1; i >= 0; i--)
1372  {
1373  if (locallock->lockOwners[i].owner != NULL)
1374  ResourceOwnerForgetLock(locallock->lockOwners[i].owner, locallock);
1375  }
1376  locallock->numLockOwners = 0;
1377  if (locallock->lockOwners != NULL)
1378  pfree(locallock->lockOwners);
1379  locallock->lockOwners = NULL;
1380 
1381  if (locallock->holdsStrongLockCount)
1382  {
1383  uint32 fasthashcode;
1384 
1385  fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
1386 
1388  Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
1389  FastPathStrongRelationLocks->count[fasthashcode]--;
1390  locallock->holdsStrongLockCount = false;
1392  }
1393 
1395  (void *) &(locallock->tag),
1396  HASH_REMOVE, NULL))
1397  elog(WARNING, "locallock table corrupted");
1398 
1399  /*
1400  * Indicate that the lock is released for certain types of locks
1401  */
1402  CheckAndSetLockHeld(locallock, false);
1403 }
void pfree(void *pointer)
Definition: mcxt.c:1175

References Assert(), CheckAndSetLockHeld(), FastPathStrongRelationLockData::count, elog, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, HASH_REMOVE, hash_search(), LOCALLOCK::hashcode, LOCALLOCK::holdsStrongLockCount, i, LockMethodLocalHash, LOCALLOCK::lockOwners, FastPathStrongRelationLockData::mutex, LOCALLOCK::numLockOwners, LOCALLOCKOWNER::owner, pfree(), ResourceOwnerForgetLock(), SpinLockAcquire, SpinLockRelease, LOCALLOCK::tag, and WARNING.

Referenced by LockAcquireExtended(), LockHasWaiters(), LockRelease(), LockReleaseAll(), and PostPrepare_Locks().

◆ SetupLockInTable()

static PROCLOCK * SetupLockInTable ( LockMethod  lockMethodTable,
PGPROC proc,
const LOCKTAG locktag,
uint32  hashcode,
LOCKMODE  lockmode 
)
static

Definition at line 1170 of file lock.c.

1172 {
1173  LOCK *lock;
1174  PROCLOCK *proclock;
1175  PROCLOCKTAG proclocktag;
1176  uint32 proclock_hashcode;
1177  bool found;
1178 
1179  /*
1180  * Find or create a lock with this tag.
1181  */
1183  (const void *) locktag,
1184  hashcode,
1186  &found);
1187  if (!lock)
1188  return NULL;
1189 
1190  /*
1191  * if it's a new lock object, initialize it
1192  */
1193  if (!found)
1194  {
1195  lock->grantMask = 0;
1196  lock->waitMask = 0;
1197  SHMQueueInit(&(lock->procLocks));
1198  ProcQueueInit(&(lock->waitProcs));
1199  lock->nRequested = 0;
1200  lock->nGranted = 0;
1201  MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
1202  MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
1203  LOCK_PRINT("LockAcquire: new", lock, lockmode);
1204  }
1205  else
1206  {
1207  LOCK_PRINT("LockAcquire: found", lock, lockmode);
1208  Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
1209  Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
1210  Assert(lock->nGranted <= lock->nRequested);
1211  }
1212 
1213  /*
1214  * Create the hash key for the proclock table.
1215  */
1216  proclocktag.myLock = lock;
1217  proclocktag.myProc = proc;
1218 
1219  proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
1220 
1221  /*
1222  * Find or create a proclock entry with this tag
1223  */
1225  (void *) &proclocktag,
1226  proclock_hashcode,
1228  &found);
1229  if (!proclock)
1230  {
1231  /* Oops, not enough shmem for the proclock */
1232  if (lock->nRequested == 0)
1233  {
1234  /*
1235  * There are no other requestors of this lock, so garbage-collect
1236  * the lock object. We *must* do this to avoid a permanent leak
1237  * of shared memory, because there won't be anything to cause
1238  * anyone to release the lock object later.
1239  */
1240  Assert(SHMQueueEmpty(&(lock->procLocks)));
1242  (void *) &(lock->tag),
1243  hashcode,
1244  HASH_REMOVE,
1245  NULL))
1246  elog(PANIC, "lock table corrupted");
1247  }
1248  return NULL;
1249  }
1250 
1251  /*
1252  * If new, initialize the new entry
1253  */
1254  if (!found)
1255  {
1256  uint32 partition = LockHashPartition(hashcode);
1257 
1258  /*
1259  * It might seem unsafe to access proclock->groupLeader without a
1260  * lock, but it's not really. Either we are initializing a proclock
1261  * on our own behalf, in which case our group leader isn't changing
1262  * because the group leader for a process can only ever be changed by
1263  * the process itself; or else we are transferring a fast-path lock to
1264  * the main lock table, in which case that process can't change it's
1265  * lock group leader without first releasing all of its locks (and in
1266  * particular the one we are currently transferring).
1267  */
1268  proclock->groupLeader = proc->lockGroupLeader != NULL ?
1269  proc->lockGroupLeader : proc;
1270  proclock->holdMask = 0;
1271  proclock->releaseMask = 0;
1272  /* Add proclock to appropriate lists */
1273  SHMQueueInsertBefore(&lock->procLocks, &proclock->lockLink);
1274  SHMQueueInsertBefore(&(proc->myProcLocks[partition]),
1275  &proclock->procLink);
1276  PROCLOCK_PRINT("LockAcquire: new", proclock);
1277  }
1278  else
1279  {
1280  PROCLOCK_PRINT("LockAcquire: found", proclock);
1281  Assert((proclock->holdMask & ~lock->grantMask) == 0);
1282 
1283 #ifdef CHECK_DEADLOCK_RISK
1284 
1285  /*
1286  * Issue warning if we already hold a lower-level lock on this object
1287  * and do not hold a lock of the requested level or higher. This
1288  * indicates a deadlock-prone coding practice (eg, we'd have a
1289  * deadlock if another backend were following the same code path at
1290  * about the same time).
1291  *
1292  * This is not enabled by default, because it may generate log entries
1293  * about user-level coding practices that are in fact safe in context.
1294  * It can be enabled to help find system-level problems.
1295  *
1296  * XXX Doing numeric comparison on the lockmodes is a hack; it'd be
1297  * better to use a table. For now, though, this works.
1298  */
1299  {
1300  int i;
1301 
1302  for (i = lockMethodTable->numLockModes; i > 0; i--)
1303  {
1304  if (proclock->holdMask & LOCKBIT_ON(i))
1305  {
1306  if (i >= (int) lockmode)
1307  break; /* safe: we have a lock >= req level */
1308  elog(LOG, "deadlock risk: raising lock level"
1309  " from %s to %s on object %u/%u/%u",
1310  lockMethodTable->lockModeNames[i],
1311  lockMethodTable->lockModeNames[lockmode],
1312  lock->tag.locktag_field1, lock->tag.locktag_field2,
1313  lock->tag.locktag_field3);
1314  break;
1315  }
1316  }
1317  }
1318 #endif /* CHECK_DEADLOCK_RISK */
1319  }
1320 
1321  /*
1322  * lock->nRequested and lock->requested[] count the total number of
1323  * requests, whether granted or waiting, so increment those immediately.
1324  * The other counts don't increment till we get the lock.
1325  */
1326  lock->nRequested++;
1327  lock->requested[lockmode]++;
1328  Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
1329 
1330  /*
1331  * We shouldn't already hold the desired lock; else locallock table is
1332  * broken.
1333  */
1334  if (proclock->holdMask & LOCKBIT_ON(lockmode))
1335  elog(ERROR, "lock %s on object %u/%u/%u is already held",
1336  lockMethodTable->lockModeNames[lockmode],
1337  lock->tag.locktag_field1, lock->tag.locktag_field2,
1338  lock->tag.locktag_field3);
1339 
1340  return proclock;
1341 }

References Assert(), elog, ERROR, LOCK::granted, LOCK::grantMask, PROCLOCK::groupLeader, HASH_ENTER_NULL, HASH_REMOVE, hash_search_with_hash_value(), PROCLOCK::holdMask, i, LOCK_PRINT, LOCKBIT_ON, PGPROC::lockGroupLeader, LockHashPartition, PROCLOCK::lockLink, LockMethodLockHash, LockMethodProcLockHash, LockMethodData::lockModeNames, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_field3, LOG, MAX_LOCKMODES, MemSet, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, PGPROC::myProcLocks, LOCK::nGranted, LOCK::nRequested, LockMethodData::numLockModes, PANIC, PROCLOCK::procLink, PROCLOCK_PRINT, ProcLockHashCode(), LOCK::procLocks, ProcQueueInit(), PROCLOCK::releaseMask, LOCK::requested, SHMQueueEmpty(), SHMQueueInit(), SHMQueueInsertBefore(), LOCK::tag, LOCK::waitMask, and LOCK::waitProcs.

Referenced by FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), LockAcquireExtended(), and VirtualXactLock().

◆ UnGrantLock()

static bool UnGrantLock ( LOCK lock,
LOCKMODE  lockmode,
PROCLOCK proclock,
LockMethod  lockMethodTable 
)
static

Definition at line 1578 of file lock.c.

1580 {
1581  bool wakeupNeeded = false;
1582 
1583  Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
1584  Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
1585  Assert(lock->nGranted <= lock->nRequested);
1586 
1587  /*
1588  * fix the general lock stats
1589  */
1590  lock->nRequested--;
1591  lock->requested[lockmode]--;
1592  lock->nGranted--;
1593  lock->granted[lockmode]--;
1594 
1595  if (lock->granted[lockmode] == 0)
1596  {
1597  /* change the conflict mask. No more of this lock type. */
1598  lock->grantMask &= LOCKBIT_OFF(lockmode);
1599  }
1600 
1601  LOCK_PRINT("UnGrantLock: updated", lock, lockmode);
1602 
1603  /*
1604  * We need only run ProcLockWakeup if the released lock conflicts with at
1605  * least one of the lock types requested by waiter(s). Otherwise whatever
1606  * conflict made them wait must still exist. NOTE: before MVCC, we could
1607  * skip wakeup if lock->granted[lockmode] was still positive. But that's
1608  * not true anymore, because the remaining granted locks might belong to
1609  * some waiter, who could now be awakened because he doesn't conflict with
1610  * his own locks.
1611  */
1612  if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
1613  wakeupNeeded = true;
1614 
1615  /*
1616  * Now fix the per-proclock state.
1617  */
1618  proclock->holdMask &= LOCKBIT_OFF(lockmode);
1619  PROCLOCK_PRINT("UnGrantLock: updated", proclock);
1620 
1621  return wakeupNeeded;
1622 }

References Assert(), LockMethodData::conflictTab, LOCK::granted, LOCK::grantMask, PROCLOCK::holdMask, LOCK_PRINT, LOCKBIT_OFF, LOCK::nGranted, LOCK::nRequested, PROCLOCK_PRINT, LOCK::requested, and LOCK::waitMask.

Referenced by LockRefindAndRelease(), LockRelease(), and LockReleaseAll().

◆ VirtualXactLock()

bool VirtualXactLock ( VirtualTransactionId  vxid,
bool  wait 
)

Definition at line 4599 of file lock.c.

4600 {
4601  LOCKTAG tag;
4602  PGPROC *proc;
4604 
4606 
4608  /* no vxid lock; localTransactionId is a normal, locked XID */
4609  return XactLockForVirtualXact(vxid, vxid.localTransactionId, wait);
4610 
4611  SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
4612 
4613  /*
4614  * If a lock table entry must be made, this is the PGPROC on whose behalf
4615  * it must be done. Note that the transaction might end or the PGPROC
4616  * might be reassigned to a new backend before we get around to examining
4617  * it, but it doesn't matter. If we find upon examination that the
4618  * relevant lxid is no longer running here, that's enough to prove that
4619  * it's no longer running anywhere.
4620  */
4621  proc = BackendIdGetProc(vxid.backendId);
4622  if (proc == NULL)
4623  return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
4624 
4625  /*
4626  * We must acquire this lock before checking the backendId and lxid
4627  * against the ones we're waiting for. The target backend will only set
4628  * or clear lxid while holding this lock.
4629  */
4631 
4632  if (proc->backendId != vxid.backendId
4633  || proc->fpLocalTransactionId != vxid.localTransactionId)
4634  {
4635  /* VXID ended */
4636  LWLockRelease(&proc->fpInfoLock);
4637  return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
4638  }
4639 
4640  /*
4641  * If we aren't asked to wait, there's no need to set up a lock table
4642  * entry. The transaction is still in progress, so just return false.
4643  */
4644  if (!wait)
4645  {
4646  LWLockRelease(&proc->fpInfoLock);
4647  return false;
4648  }
4649 
4650  /*
4651  * OK, we're going to need to sleep on the VXID. But first, we must set
4652  * up the primary lock table entry, if needed (ie, convert the proc's
4653  * fast-path lock on its VXID to a regular lock).
4654  */
4655  if (proc->fpVXIDLock)
4656  {
4657  PROCLOCK *proclock;
4658  uint32 hashcode;
4659  LWLock *partitionLock;
4660 
4661  hashcode = LockTagHashCode(&tag);
4662 
4663  partitionLock = LockHashPartitionLock(hashcode);
4664  LWLockAcquire(partitionLock, LW_EXCLUSIVE);
4665 
4667  &tag, hashcode, ExclusiveLock);
4668  if (!proclock)
4669  {
4670  LWLockRelease(partitionLock);
4671  LWLockRelease(&proc->fpInfoLock);
4672  ereport(ERROR,
4673  (errcode(ERRCODE_OUT_OF_MEMORY),
4674  errmsg("out of shared memory"),
4675  errhint("You might need to increase max_locks_per_transaction.")));
4676  }
4677  GrantLock(proclock->tag.myLock, proclock, ExclusiveLock);
4678 
4679  LWLockRelease(partitionLock);
4680 
4681  proc->fpVXIDLock = false;
4682  }
4683 
4684  /*
4685  * If the proc has an XID now, we'll avoid a TwoPhaseGetXidByVirtualXID()
4686  * search. The proc might have assigned this XID but not yet locked it,
4687  * in which case the proc will lock this XID before releasing the VXID.
4688  * The fpInfoLock critical section excludes VirtualXactLockTableCleanup(),
4689  * so we won't save an XID of a different VXID. It doesn't matter whether
4690  * we save this before or after setting up the primary lock table entry.
4691  */
4692  xid = proc->xid;
4693 
4694  /* Done with proc->fpLockBits */
4695  LWLockRelease(&proc->fpInfoLock);
4696 
4697  /* Time to wait. */
4698  (void) LockAcquire(&tag, ShareLock, false, false);
4699 
4700  LockRelease(&tag, ShareLock, false);
4701  return XactLockForVirtualXact(vxid, xid, wait);
4702 }
static bool XactLockForVirtualXact(VirtualTransactionId vxid, TransactionId xid, bool wait)
Definition: lock.c:4548
LockAcquireResult LockAcquire(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait)
Definition: lock.c:747
#define VirtualTransactionIdIsRecoveredPreparedXact(vxid)
Definition: lock.h:74
#define ShareLock
Definition: lockdefs.h:40
PGPROC * BackendIdGetProc(int backendID)
Definition: sinvaladt.c:385
#define InvalidTransactionId
Definition: transam.h:31

References Assert(), VirtualTransactionId::backendId, PGPROC::backendId, BackendIdGetProc(), DEFAULT_LOCKMETHOD, ereport, errcode(), errhint(), errmsg(), ERROR, ExclusiveLock, PGPROC::fpInfoLock, PGPROC::fpLocalTransactionId, PGPROC::fpVXIDLock, GrantLock(), InvalidTransactionId, VirtualTransactionId::localTransactionId, LockAcquire(), LockHashPartitionLock, LockMethods, LockRelease(), LockTagHashCode(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), PROCLOCKTAG::myLock, SET_LOCKTAG_VIRTUALTRANSACTION, SetupLockInTable(), ShareLock, PROCLOCK::tag, VirtualTransactionIdIsRecoveredPreparedXact, VirtualTransactionIdIsValid, XactLockForVirtualXact(), and PGPROC::xid.

Referenced by ResolveRecoveryConflictWithVirtualXIDs(), WaitForLockersMultiple(), and WaitForOlderSnapshots().

◆ VirtualXactLockTableCleanup()

void VirtualXactLockTableCleanup ( void  )

Definition at line 4499 of file lock.c.

4500 {
4501  bool fastpath;
4502  LocalTransactionId lxid;
4503 
4505 
4506  /*
4507  * Clean up shared memory state.
4508  */
4510 
4511  fastpath = MyProc->fpVXIDLock;
4512  lxid = MyProc->fpLocalTransactionId;
4513  MyProc->fpVXIDLock = false;
4515 
4517 
4518  /*
4519  * If fpVXIDLock has been cleared without touching fpLocalTransactionId,
4520  * that means someone transferred the lock to the main lock table.
4521  */
4522  if (!fastpath && LocalTransactionIdIsValid(lxid))
4523  {
4524  VirtualTransactionId vxid;
4525  LOCKTAG locktag;
4526 
4527  vxid.backendId = MyBackendId;
4528  vxid.localTransactionId = lxid;
4529  SET_LOCKTAG_VIRTUALTRANSACTION(locktag, vxid);
4530 
4532  &locktag, ExclusiveLock, false);
4533  }
4534 }
uint32 LocalTransactionId
Definition: c.h:600
BackendId MyBackendId
Definition: globals.c:85
#define LocalTransactionIdIsValid(lxid)
Definition: lock.h:71

References Assert(), VirtualTransactionId::backendId, PGPROC::backendId, DEFAULT_LOCKMETHOD, ExclusiveLock, PGPROC::fpInfoLock, PGPROC::fpLocalTransactionId, PGPROC::fpVXIDLock, InvalidBackendId, InvalidLocalTransactionId, VirtualTransactionId::localTransactionId, LocalTransactionIdIsValid, LockMethods, LockRefindAndRelease(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MyBackendId, MyProc, and SET_LOCKTAG_VIRTUALTRANSACTION.

Referenced by LockReleaseAll(), and ShutdownRecoveryTransactionEnvironment().

◆ VirtualXactLockTableInsert()

◆ WaitOnLock()

static void WaitOnLock ( LOCALLOCK locallock,
ResourceOwner  owner 
)
static

Definition at line 1814 of file lock.c.

1815 {
1816  LOCKMETHODID lockmethodid = LOCALLOCK_LOCKMETHOD(*locallock);
1817  LockMethod lockMethodTable = LockMethods[lockmethodid];
1818  char *volatile new_status = NULL;
1819 
1820  LOCK_PRINT("WaitOnLock: sleeping on lock",
1821  locallock->lock, locallock->tag.mode);
1822 
1823  /* Report change to waiting status */
1825  {
1826  const char *old_status;
1827  int len;
1828 
1829  old_status = get_ps_display(&len);
1830  new_status = (char *) palloc(len + 8 + 1);
1831  memcpy(new_status, old_status, len);
1832  strcpy(new_status + len, " waiting");
1833  set_ps_display(new_status);
1834  new_status[len] = '\0'; /* truncate off " waiting" */
1835  }
1836 
1837  awaitedLock = locallock;
1838  awaitedOwner = owner;
1839 
1840  /*
1841  * NOTE: Think not to put any shared-state cleanup after the call to
1842  * ProcSleep, in either the normal or failure path. The lock state must
1843  * be fully set by the lock grantor, or by CheckDeadLock if we give up
1844  * waiting for the lock. This is necessary because of the possibility
1845  * that a cancel/die interrupt will interrupt ProcSleep after someone else
1846  * grants us the lock, but before we've noticed it. Hence, after granting,
1847  * the locktable state must fully reflect the fact that we own the lock;
1848  * we can't do additional work on return.
1849  *
1850  * We can and do use a PG_TRY block to try to clean up after failure, but
1851  * this still has a major limitation: elog(FATAL) can occur while waiting
1852  * (eg, a "die" interrupt), and then control won't come back here. So all
1853  * cleanup of essential state should happen in LockErrorCleanup, not here.
1854  * We can use PG_TRY to clear the "waiting" status flags, since doing that
1855  * is unimportant if the process exits.
1856  */
1857  PG_TRY();
1858  {
1859  if (ProcSleep(locallock, lockMethodTable) != PROC_WAIT_STATUS_OK)
1860  {
1861  /*
1862  * We failed as a result of a deadlock, see CheckDeadLock(). Quit
1863  * now.
1864  */
1865  awaitedLock = NULL;
1866  LOCK_PRINT("WaitOnLock: aborting on lock",
1867  locallock->lock, locallock->tag.mode);
1869 
1870  /*
1871  * Now that we aren't holding the partition lock, we can give an
1872  * error report including details about the detected deadlock.
1873  */
1874  DeadLockReport();
1875  /* not reached */
1876  }
1877  }
1878  PG_CATCH();
1879  {
1880  /* In this path, awaitedLock remains set until LockErrorCleanup */
1881 
1882  /* Report change to non-waiting status */
1884  {
1885  set_ps_display(new_status);
1886  pfree(new_status);
1887  }
1888 
1889  /* and propagate the error */
1890  PG_RE_THROW();
1891  }
1892  PG_END_TRY();
1893 
1894  awaitedLock = NULL;
1895 
1896  /* Report change to non-waiting status */
1898  {
1899  set_ps_display(new_status);
1900  pfree(new_status);
1901  }
1902 
1903  LOCK_PRINT("WaitOnLock: wakeup on lock",
1904  locallock->lock, locallock->tag.mode);
1905 }
void DeadLockReport(void)
Definition: deadlock.c:1090
#define PG_RE_THROW()
Definition: elog.h:340
#define PG_END_TRY()
Definition: elog.h:324
#define PG_TRY()
Definition: elog.h:299
#define PG_CATCH()
Definition: elog.h:309
@ PROC_WAIT_STATUS_OK
Definition: proc.h:122
const char * get_ps_display(int *displen)
Definition: ps_status.c:430
bool update_process_title
Definition: ps_status.c:36
void set_ps_display(const char *activity)
Definition: ps_status.c:349
ProcWaitStatus ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
Definition: proc.c:1045

References awaitedLock, awaitedOwner, DeadLockReport(), get_ps_display(), LOCALLOCK::hashcode, len, LOCALLOCK_LOCKMETHOD, LOCALLOCK::lock, LOCK_PRINT, LockHashPartitionLock, LockMethods, LWLockRelease(), LOCALLOCKTAG::mode, palloc(), pfree(), PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, PROC_WAIT_STATUS_OK, ProcSleep(), set_ps_display(), LOCALLOCK::tag, and update_process_title.

Referenced by LockAcquireExtended().

◆ XactLockForVirtualXact()

static bool XactLockForVirtualXact ( VirtualTransactionId  vxid,
TransactionId  xid,
bool  wait 
)
static

Definition at line 4548 of file lock.c.

4550 {
4551  bool more = false;
4552 
4553  /* There is no point to wait for 2PCs if you have no 2PCs. */
4554  if (max_prepared_xacts == 0)
4555  return true;
4556 
4557  do
4558  {
4559  LockAcquireResult lar;
4560  LOCKTAG tag;
4561 
4562  /* Clear state from previous iterations. */
4563  if (more)
4564  {
4565  xid = InvalidTransactionId;
4566  more = false;
4567  }
4568 
4569  /* If we have no xid, try to find one. */
4570  if (!TransactionIdIsValid(xid))
4571  xid = TwoPhaseGetXidByVirtualXID(vxid, &more);
4572  if (!TransactionIdIsValid(xid))
4573  {
4574  Assert(!more);
4575  return true;
4576  }
4577 
4578  /* Check or wait for XID completion. */
4579  SET_LOCKTAG_TRANSACTION(tag, xid);
4580  lar = LockAcquire(&tag, ShareLock, false, !wait);
4581  if (lar == LOCKACQUIRE_NOT_AVAIL)
4582  return false;
4583  LockRelease(&tag, ShareLock, false);
4584  } while (more);
4585 
4586  return true;
4587 }
#define SET_LOCKTAG_TRANSACTION(locktag, xid)
Definition: lock.h:229
LockAcquireResult
Definition: lock.h:493
TransactionId TwoPhaseGetXidByVirtualXID(VirtualTransactionId vxid, bool *have_more)
Definition: twophase.c:872

References Assert(), InvalidTransactionId, LockAcquire(), LOCKACQUIRE_NOT_AVAIL, LockRelease(), max_prepared_xacts, SET_LOCKTAG_TRANSACTION, ShareLock, TransactionIdIsValid, and TwoPhaseGetXidByVirtualXID().

Referenced by VirtualXactLock().

Variable Documentation

◆ awaitedLock

LOCALLOCK* awaitedLock
static

Definition at line 288 of file lock.c.

Referenced by GrantAwaitedLock(), and WaitOnLock().

◆ awaitedOwner

ResourceOwner awaitedOwner
static

Definition at line 289 of file lock.c.

Referenced by GrantAwaitedLock(), and WaitOnLock().

◆ default_lockmethod

const LockMethodData default_lockmethod
static
Initial value:
= {
}
static bool Dummy_trace
Definition: lock.c:123
static const char *const lock_mode_names[]
Definition: lock.c:109
static const LOCKMASK LockConflicts[]
Definition: lock.c:66
#define MaxLockMode
Definition: lockdefs.h:45

Definition at line 126 of file lock.c.

◆ Dummy_trace

bool Dummy_trace = false
static

Definition at line 123 of file lock.c.

◆ FastPathLocalUseCount

int FastPathLocalUseCount = 0
static

◆ FastPathStrongRelationLocks

◆ lock_mode_names

const char* const lock_mode_names[]
static
Initial value:
=
{
"INVALID",
"AccessShareLock",
"RowShareLock",
"RowExclusiveLock",
"ShareUpdateExclusiveLock",
"ShareLock",
"ShareRowExclusiveLock",
"ExclusiveLock",
"AccessExclusiveLock"
}

Definition at line 109 of file lock.c.

◆ LockConflicts

const LOCKMASK LockConflicts[]
static

Definition at line 66 of file lock.c.

◆ LockMethodLocalHash