PostgreSQL Source Code  git master
lwlock.c File Reference
#include "postgres.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "pgstat.h"
#include "port/pg_bitutils.h"
#include "postmaster/postmaster.h"
#include "storage/proc.h"
#include "storage/proclist.h"
#include "storage/spin.h"
#include "utils/memutils.h"
Include dependency graph for lwlock.c:

Go to the source code of this file.

Data Structures

struct  LWLockHandle
 
struct  NamedLWLockTrancheRequest
 

Macros

#define LW_FLAG_HAS_WAITERS   ((uint32) 1 << 30)
 
#define LW_FLAG_RELEASE_OK   ((uint32) 1 << 29)
 
#define LW_FLAG_LOCKED   ((uint32) 1 << 28)
 
#define LW_VAL_EXCLUSIVE   ((uint32) 1 << 24)
 
#define LW_VAL_SHARED   1
 
#define LW_LOCK_MASK   ((uint32) ((1 << 25)-1))
 
#define LW_SHARED_MASK   ((uint32) ((1 << 24)-1))
 
#define MAX_SIMUL_LWLOCKS   200
 
#define T_NAME(lock)    GetLWTrancheName((lock)->tranche)
 
#define PRINT_LWDEBUG(a, b, c)   ((void)0)
 
#define LOG_LWDEBUG(a, b, c)   ((void)0)
 

Typedefs

typedef struct LWLockHandle LWLockHandle
 
typedef struct NamedLWLockTrancheRequest NamedLWLockTrancheRequest
 

Functions

 StaticAssertDecl (LW_VAL_EXCLUSIVE >(uint32) MAX_BACKENDS, "MAX_BACKENDS too big for lwlock.c")
 
 StaticAssertDecl (lengthof(BuiltinTrancheNames)==LWTRANCHE_FIRST_USER_DEFINED, "missing entries in BuiltinTrancheNames[]")
 
static void InitializeLWLocks (void)
 
static void LWLockReportWaitStart (LWLock *lock)
 
static void LWLockReportWaitEnd (void)
 
static const char * GetLWTrancheName (uint16 trancheId)
 
static int NumLWLocksForNamedTranches (void)
 
Size LWLockShmemSize (void)
 
void CreateLWLocks (void)
 
void InitLWLockAccess (void)
 
LWLockPaddedGetNamedLWLockTranche (const char *tranche_name)
 
int LWLockNewTrancheId (void)
 
void LWLockRegisterTranche (int tranche_id, const char *tranche_name)
 
void RequestNamedLWLockTranche (const char *tranche_name, int num_lwlocks)
 
void LWLockInitialize (LWLock *lock, int tranche_id)
 
const char * GetLWLockIdentifier (uint32 classId, uint16 eventId)
 
static bool LWLockAttemptLock (LWLock *lock, LWLockMode mode)
 
static void LWLockWaitListLock (LWLock *lock)
 
static void LWLockWaitListUnlock (LWLock *lock)
 
static void LWLockWakeup (LWLock *lock)
 
static void LWLockQueueSelf (LWLock *lock, LWLockMode mode)
 
static void LWLockDequeueSelf (LWLock *lock)
 
bool LWLockAcquire (LWLock *lock, LWLockMode mode)
 
bool LWLockConditionalAcquire (LWLock *lock, LWLockMode mode)
 
bool LWLockAcquireOrWait (LWLock *lock, LWLockMode mode)
 
static bool LWLockConflictsWithVar (LWLock *lock, pg_atomic_uint64 *valptr, uint64 oldval, uint64 *newval, bool *result)
 
bool LWLockWaitForVar (LWLock *lock, pg_atomic_uint64 *valptr, uint64 oldval, uint64 *newval)
 
void LWLockUpdateVar (LWLock *lock, pg_atomic_uint64 *valptr, uint64 val)
 
void LWLockRelease (LWLock *lock)
 
void LWLockReleaseClearVar (LWLock *lock, pg_atomic_uint64 *valptr, uint64 val)
 
void LWLockReleaseAll (void)
 
bool LWLockHeldByMe (LWLock *lock)
 
bool LWLockAnyHeldByMe (LWLock *lock, int nlocks, size_t stride)
 
bool LWLockHeldByMeInMode (LWLock *lock, LWLockMode mode)
 

Variables

slock_tShmemLock
 
const char *const IndividualLWLockNames []
 
static const char *const BuiltinTrancheNames []
 
static const char ** LWLockTrancheNames = NULL
 
static int LWLockTrancheNamesAllocated = 0
 
LWLockPaddedMainLWLockArray = NULL
 
static int num_held_lwlocks = 0
 
static LWLockHandle held_lwlocks [MAX_SIMUL_LWLOCKS]
 
static NamedLWLockTrancheRequestNamedLWLockTrancheRequestArray = NULL
 
static int NamedLWLockTrancheRequestsAllocated = 0
 
int NamedLWLockTrancheRequests = 0
 
NamedLWLockTrancheNamedLWLockTrancheArray = NULL
 

Macro Definition Documentation

◆ LOG_LWDEBUG

#define LOG_LWDEBUG (   a,
  b,
  c 
)    ((void)0)

Definition at line 300 of file lwlock.c.

◆ LW_FLAG_HAS_WAITERS

#define LW_FLAG_HAS_WAITERS   ((uint32) 1 << 30)

Definition at line 97 of file lwlock.c.

◆ LW_FLAG_LOCKED

#define LW_FLAG_LOCKED   ((uint32) 1 << 28)

Definition at line 99 of file lwlock.c.

◆ LW_FLAG_RELEASE_OK

#define LW_FLAG_RELEASE_OK   ((uint32) 1 << 29)

Definition at line 98 of file lwlock.c.

◆ LW_LOCK_MASK

#define LW_LOCK_MASK   ((uint32) ((1 << 25)-1))

Definition at line 104 of file lwlock.c.

◆ LW_SHARED_MASK

#define LW_SHARED_MASK   ((uint32) ((1 << 24)-1))

Definition at line 106 of file lwlock.c.

◆ LW_VAL_EXCLUSIVE

#define LW_VAL_EXCLUSIVE   ((uint32) 1 << 24)

Definition at line 101 of file lwlock.c.

◆ LW_VAL_SHARED

#define LW_VAL_SHARED   1

Definition at line 102 of file lwlock.c.

◆ MAX_SIMUL_LWLOCKS

#define MAX_SIMUL_LWLOCKS   200

Definition at line 197 of file lwlock.c.

◆ PRINT_LWDEBUG

#define PRINT_LWDEBUG (   a,
  b,
  c 
)    ((void)0)

Definition at line 299 of file lwlock.c.

◆ T_NAME

#define T_NAME (   lock)     GetLWTrancheName((lock)->tranche)

Definition at line 235 of file lwlock.c.

Typedef Documentation

◆ LWLockHandle

typedef struct LWLockHandle LWLockHandle

◆ NamedLWLockTrancheRequest

Function Documentation

◆ CreateLWLocks()

void CreateLWLocks ( void  )

Definition at line 451 of file lwlock.c.

452 {
453  if (!IsUnderPostmaster)
454  {
455  Size spaceLocks = LWLockShmemSize();
456  int *LWLockCounter;
457  char *ptr;
458 
459  /* Allocate space */
460  ptr = (char *) ShmemAlloc(spaceLocks);
461 
462  /* Leave room for dynamic allocation of tranches */
463  ptr += sizeof(int);
464 
465  /* Ensure desired alignment of LWLock array */
466  ptr += LWLOCK_PADDED_SIZE - ((uintptr_t) ptr) % LWLOCK_PADDED_SIZE;
467 
468  MainLWLockArray = (LWLockPadded *) ptr;
469 
470  /*
471  * Initialize the dynamic-allocation counter for tranches, which is
472  * stored just before the first LWLock.
473  */
474  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
475  *LWLockCounter = LWTRANCHE_FIRST_USER_DEFINED;
476 
477  /* Initialize all LWLocks */
479  }
480 
481  /* Register named extension LWLock tranches in the current process. */
482  for (int i = 0; i < NamedLWLockTrancheRequests; i++)
484  NamedLWLockTrancheArray[i].trancheName);
485 }
size_t Size
Definition: c.h:592
bool IsUnderPostmaster
Definition: globals.c:117
int i
Definition: isn.c:73
NamedLWLockTranche * NamedLWLockTrancheArray
Definition: lwlock.c:228
void LWLockRegisterTranche(int tranche_id, const char *tranche_name)
Definition: lwlock.c:628
int NamedLWLockTrancheRequests
Definition: lwlock.c:225
static void InitializeLWLocks(void)
Definition: lwlock.c:491
LWLockPadded * MainLWLockArray
Definition: lwlock.c:189
Size LWLockShmemSize(void)
Definition: lwlock.c:421
#define LWLOCK_PADDED_SIZE
Definition: lwlock.h:61
@ LWTRANCHE_FIRST_USER_DEFINED
Definition: lwlock.h:219
void * ShmemAlloc(Size size)
Definition: shmem.c:152

References i, InitializeLWLocks(), IsUnderPostmaster, LWLOCK_PADDED_SIZE, LWLockRegisterTranche(), LWLockShmemSize(), LWTRANCHE_FIRST_USER_DEFINED, MainLWLockArray, NamedLWLockTrancheArray, NamedLWLockTrancheRequests, and ShmemAlloc().

Referenced by CreateOrAttachShmemStructs().

◆ GetLWLockIdentifier()

const char* GetLWLockIdentifier ( uint32  classId,
uint16  eventId 
)

Definition at line 771 of file lwlock.c.

772 {
773  Assert(classId == PG_WAIT_LWLOCK);
774  /* The event IDs are just tranche numbers. */
775  return GetLWTrancheName(eventId);
776 }
Assert(fmt[strlen(fmt) - 1] !='\n')
static const char * GetLWTrancheName(uint16 trancheId)
Definition: lwlock.c:743
#define PG_WAIT_LWLOCK
Definition: wait_event.h:18

References Assert(), GetLWTrancheName(), and PG_WAIT_LWLOCK.

Referenced by pgstat_get_wait_event().

◆ GetLWTrancheName()

static const char * GetLWTrancheName ( uint16  trancheId)
static

Definition at line 743 of file lwlock.c.

744 {
745  /* Individual LWLock? */
746  if (trancheId < NUM_INDIVIDUAL_LWLOCKS)
747  return IndividualLWLockNames[trancheId];
748 
749  /* Built-in tranche? */
750  if (trancheId < LWTRANCHE_FIRST_USER_DEFINED)
751  return BuiltinTrancheNames[trancheId];
752 
753  /*
754  * It's an extension tranche, so look in LWLockTrancheNames[]. However,
755  * it's possible that the tranche has never been registered in the current
756  * process, in which case give up and return "extension".
757  */
758  trancheId -= LWTRANCHE_FIRST_USER_DEFINED;
759 
760  if (trancheId >= LWLockTrancheNamesAllocated ||
761  LWLockTrancheNames[trancheId] == NULL)
762  return "extension";
763 
764  return LWLockTrancheNames[trancheId];
765 }
static int LWLockTrancheNamesAllocated
Definition: lwlock.c:182
const char *const IndividualLWLockNames[]
static const char *const BuiltinTrancheNames[]
Definition: lwlock.c:131
static const char ** LWLockTrancheNames
Definition: lwlock.c:181

References BuiltinTrancheNames, IndividualLWLockNames, LWLockTrancheNames, LWLockTrancheNamesAllocated, and LWTRANCHE_FIRST_USER_DEFINED.

Referenced by GetLWLockIdentifier().

◆ GetNamedLWLockTranche()

LWLockPadded* GetNamedLWLockTranche ( const char *  tranche_name)

Definition at line 574 of file lwlock.c.

575 {
576  int lock_pos;
577  int i;
578 
579  /*
580  * Obtain the position of base address of LWLock belonging to requested
581  * tranche_name in MainLWLockArray. LWLocks for named tranches are placed
582  * in MainLWLockArray after fixed locks.
583  */
584  lock_pos = NUM_FIXED_LWLOCKS;
585  for (i = 0; i < NamedLWLockTrancheRequests; i++)
586  {
587  if (strcmp(NamedLWLockTrancheRequestArray[i].tranche_name,
588  tranche_name) == 0)
589  return &MainLWLockArray[lock_pos];
590 
592  }
593 
594  elog(ERROR, "requested tranche is not registered");
595 
596  /* just to keep compiler quiet */
597  return NULL;
598 }
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:224
static NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:216
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:111

References elog, ERROR, i, MainLWLockArray, NamedLWLockTrancheRequestArray, NamedLWLockTrancheRequests, NUM_FIXED_LWLOCKS, and NamedLWLockTrancheRequest::num_lwlocks.

Referenced by pgss_shmem_startup().

◆ InitializeLWLocks()

static void InitializeLWLocks ( void  )
static

Definition at line 491 of file lwlock.c.

492 {
493  int numNamedLocks = NumLWLocksForNamedTranches();
494  int id;
495  int i;
496  int j;
497  LWLockPadded *lock;
498 
499  /* Initialize all individual LWLocks in main array */
500  for (id = 0, lock = MainLWLockArray; id < NUM_INDIVIDUAL_LWLOCKS; id++, lock++)
501  LWLockInitialize(&lock->lock, id);
502 
503  /* Initialize buffer mapping LWLocks in main array */
505  for (id = 0; id < NUM_BUFFER_PARTITIONS; id++, lock++)
507 
508  /* Initialize lmgrs' LWLocks in main array */
510  for (id = 0; id < NUM_LOCK_PARTITIONS; id++, lock++)
512 
513  /* Initialize predicate lmgrs' LWLocks in main array */
515  for (id = 0; id < NUM_PREDICATELOCK_PARTITIONS; id++, lock++)
517 
518  /*
519  * Copy the info about any named tranches into shared memory (so that
520  * other processes can see it), and initialize the requested LWLocks.
521  */
523  {
524  char *trancheNames;
525 
527  &MainLWLockArray[NUM_FIXED_LWLOCKS + numNamedLocks];
528 
529  trancheNames = (char *) NamedLWLockTrancheArray +
532 
533  for (i = 0; i < NamedLWLockTrancheRequests; i++)
534  {
535  NamedLWLockTrancheRequest *request;
536  NamedLWLockTranche *tranche;
537  char *name;
538 
539  request = &NamedLWLockTrancheRequestArray[i];
540  tranche = &NamedLWLockTrancheArray[i];
541 
542  name = trancheNames;
543  trancheNames += strlen(request->tranche_name) + 1;
544  strcpy(name, request->tranche_name);
545  tranche->trancheId = LWLockNewTrancheId();
546  tranche->trancheName = name;
547 
548  for (j = 0; j < request->num_lwlocks; j++, lock++)
549  LWLockInitialize(&lock->lock, tranche->trancheId);
550  }
551  }
552 }
int j
Definition: isn.c:74
int LWLockNewTrancheId(void)
Definition: lwlock.c:604
static int NumLWLocksForNamedTranches(void)
Definition: lwlock.c:406
void LWLockInitialize(LWLock *lock, int tranche_id)
Definition: lwlock.c:707
#define BUFFER_MAPPING_LWLOCK_OFFSET
Definition: lwlock.h:106
#define NUM_LOCK_PARTITIONS
Definition: lwlock.h:99
@ LWTRANCHE_PREDICATE_LOCK_MANAGER
Definition: lwlock.h:195
@ LWTRANCHE_BUFFER_MAPPING
Definition: lwlock.h:193
@ LWTRANCHE_LOCK_MANAGER
Definition: lwlock.h:194
#define LOCK_MANAGER_LWLOCK_OFFSET
Definition: lwlock.h:107
#define NUM_BUFFER_PARTITIONS
Definition: lwlock.h:95
#define PREDICATELOCK_MANAGER_LWLOCK_OFFSET
Definition: lwlock.h:109
#define NUM_PREDICATELOCK_PARTITIONS
Definition: lwlock.h:103
char tranche_name[NAMEDATALEN]
Definition: lwlock.c:212
char * trancheName
Definition: lwlock.h:79
LWLock lock
Definition: lwlock.h:69
const char * name

References BUFFER_MAPPING_LWLOCK_OFFSET, i, j, LWLockPadded::lock, LOCK_MANAGER_LWLOCK_OFFSET, LWLockInitialize(), LWLockNewTrancheId(), LWTRANCHE_BUFFER_MAPPING, LWTRANCHE_LOCK_MANAGER, LWTRANCHE_PREDICATE_LOCK_MANAGER, MainLWLockArray, name, NamedLWLockTrancheArray, NamedLWLockTrancheRequestArray, NamedLWLockTrancheRequests, NUM_BUFFER_PARTITIONS, NUM_FIXED_LWLOCKS, NUM_LOCK_PARTITIONS, NamedLWLockTrancheRequest::num_lwlocks, NUM_PREDICATELOCK_PARTITIONS, NumLWLocksForNamedTranches(), PREDICATELOCK_MANAGER_LWLOCK_OFFSET, NamedLWLockTrancheRequest::tranche_name, NamedLWLockTranche::trancheId, and NamedLWLockTranche::trancheName.

Referenced by CreateLWLocks().

◆ InitLWLockAccess()

void InitLWLockAccess ( void  )

Definition at line 558 of file lwlock.c.

559 {
560 #ifdef LWLOCK_STATS
561  init_lwlock_stats();
562 #endif
563 }

Referenced by InitAuxiliaryProcess(), and InitProcess().

◆ LWLockAcquire()

bool LWLockAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1172 of file lwlock.c.

1173 {
1174  PGPROC *proc = MyProc;
1175  bool result = true;
1176  int extraWaits = 0;
1177 #ifdef LWLOCK_STATS
1178  lwlock_stats *lwstats;
1179 
1180  lwstats = get_lwlock_stats_entry(lock);
1181 #endif
1182 
1184 
1185  PRINT_LWDEBUG("LWLockAcquire", lock, mode);
1186 
1187 #ifdef LWLOCK_STATS
1188  /* Count lock acquisition attempts */
1189  if (mode == LW_EXCLUSIVE)
1190  lwstats->ex_acquire_count++;
1191  else
1192  lwstats->sh_acquire_count++;
1193 #endif /* LWLOCK_STATS */
1194 
1195  /*
1196  * We can't wait if we haven't got a PGPROC. This should only occur
1197  * during bootstrap or shared memory initialization. Put an Assert here
1198  * to catch unsafe coding practices.
1199  */
1200  Assert(!(proc == NULL && IsUnderPostmaster));
1201 
1202  /* Ensure we will have room to remember the lock */
1204  elog(ERROR, "too many LWLocks taken");
1205 
1206  /*
1207  * Lock out cancel/die interrupts until we exit the code section protected
1208  * by the LWLock. This ensures that interrupts will not interfere with
1209  * manipulations of data structures in shared memory.
1210  */
1211  HOLD_INTERRUPTS();
1212 
1213  /*
1214  * Loop here to try to acquire lock after each time we are signaled by
1215  * LWLockRelease.
1216  *
1217  * NOTE: it might seem better to have LWLockRelease actually grant us the
1218  * lock, rather than retrying and possibly having to go back to sleep. But
1219  * in practice that is no good because it means a process swap for every
1220  * lock acquisition when two or more processes are contending for the same
1221  * lock. Since LWLocks are normally used to protect not-very-long
1222  * sections of computation, a process needs to be able to acquire and
1223  * release the same lock many times during a single CPU time slice, even
1224  * in the presence of contention. The efficiency of being able to do that
1225  * outweighs the inefficiency of sometimes wasting a process dispatch
1226  * cycle because the lock is not free when a released waiter finally gets
1227  * to run. See pgsql-hackers archives for 29-Dec-01.
1228  */
1229  for (;;)
1230  {
1231  bool mustwait;
1232 
1233  /*
1234  * Try to grab the lock the first time, we're not in the waitqueue
1235  * yet/anymore.
1236  */
1237  mustwait = LWLockAttemptLock(lock, mode);
1238 
1239  if (!mustwait)
1240  {
1241  LOG_LWDEBUG("LWLockAcquire", lock, "immediately acquired lock");
1242  break; /* got the lock */
1243  }
1244 
1245  /*
1246  * Ok, at this point we couldn't grab the lock on the first try. We
1247  * cannot simply queue ourselves to the end of the list and wait to be
1248  * woken up because by now the lock could long have been released.
1249  * Instead add us to the queue and try to grab the lock again. If we
1250  * succeed we need to revert the queuing and be happy, otherwise we
1251  * recheck the lock. If we still couldn't grab it, we know that the
1252  * other locker will see our queue entries when releasing since they
1253  * existed before we checked for the lock.
1254  */
1255 
1256  /* add to the queue */
1257  LWLockQueueSelf(lock, mode);
1258 
1259  /* we're now guaranteed to be woken up if necessary */
1260  mustwait = LWLockAttemptLock(lock, mode);
1261 
1262  /* ok, grabbed the lock the second time round, need to undo queueing */
1263  if (!mustwait)
1264  {
1265  LOG_LWDEBUG("LWLockAcquire", lock, "acquired, undoing queue");
1266 
1267  LWLockDequeueSelf(lock);
1268  break;
1269  }
1270 
1271  /*
1272  * Wait until awakened.
1273  *
1274  * It is possible that we get awakened for a reason other than being
1275  * signaled by LWLockRelease. If so, loop back and wait again. Once
1276  * we've gotten the LWLock, re-increment the sema by the number of
1277  * additional signals received.
1278  */
1279  LOG_LWDEBUG("LWLockAcquire", lock, "waiting");
1280 
1281 #ifdef LWLOCK_STATS
1282  lwstats->block_count++;
1283 #endif
1284 
1285  LWLockReportWaitStart(lock);
1286  if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED())
1287  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1288 
1289  for (;;)
1290  {
1291  PGSemaphoreLock(proc->sem);
1292  if (proc->lwWaiting == LW_WS_NOT_WAITING)
1293  break;
1294  extraWaits++;
1295  }
1296 
1297  /* Retrying, allow LWLockRelease to release waiters again. */
1299 
1300 #ifdef LOCK_DEBUG
1301  {
1302  /* not waiting anymore */
1303  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1304 
1305  Assert(nwaiters < MAX_BACKENDS);
1306  }
1307 #endif
1308 
1309  if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED())
1310  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1312 
1313  LOG_LWDEBUG("LWLockAcquire", lock, "awakened");
1314 
1315  /* Now loop back and try to acquire lock again. */
1316  result = false;
1317  }
1318 
1319  if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_ENABLED())
1320  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode);
1321 
1322  /* Add lock to list of locks held by this backend */
1325 
1326  /*
1327  * Fix the process wait semaphore's count for any absorbed wakeups.
1328  */
1329  while (extraWaits-- > 0)
1330  PGSemaphoreUnlock(proc->sem);
1331 
1332  return result;
1333 }
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:405
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:376
unsigned int uint32
Definition: c.h:493
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:169
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:207
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:788
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:734
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:98
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:197
#define T_NAME(lock)
Definition: lwlock.c:235
static int num_held_lwlocks
Definition: lwlock.c:206
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:300
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1040
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:299
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:725
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1083
@ LW_WS_NOT_WAITING
Definition: lwlock.h:29
@ LW_SHARED
Definition: lwlock.h:117
@ LW_EXCLUSIVE
Definition: lwlock.h:116
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:133
static PgChecksumMode mode
Definition: pg_checksums.c:56
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:320
#define MAX_BACKENDS
Definition: postmaster.h:95
PGPROC * MyProc
Definition: proc.c:66
LWLockMode mode
Definition: lwlock.c:203
LWLock * lock
Definition: lwlock.c:202
pg_atomic_uint32 state
Definition: lwlock.h:43
Definition: proc.h:157
PGSemaphore sem
Definition: proc.h:162
uint8 lwWaiting
Definition: proc.h:219

References Assert(), elog, ERROR, held_lwlocks, HOLD_INTERRUPTS, IsUnderPostmaster, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_RELEASE_OK, LW_SHARED, LW_WS_NOT_WAITING, LWLockAttemptLock(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MAX_SIMUL_LWLOCKS, LWLockHandle::mode, mode, MyProc, num_held_lwlocks, pg_atomic_fetch_or_u32(), pg_atomic_fetch_sub_u32(), PG_USED_FOR_ASSERTS_ONLY, PGSemaphoreLock(), PGSemaphoreUnlock(), PRINT_LWDEBUG, PGPROC::sem, LWLock::state, and T_NAME.

Referenced by _bt_end_vacuum(), _bt_start_vacuum(), _bt_vacuum_cycleid(), AbsorbSyncRequests(), ActivateCommitTs(), AdjustToFullTransactionId(), AdvanceNextFullTransactionIdPastXid(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_load_buffers(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AtAbort_Twophase(), AtEOXact_LogicalRepWorkers(), AtPrepare_PredicateLocks(), attach_internal(), autoprewarm_main(), autoprewarm_start_worker(), AutoVacuumRequestWork(), AutoVacWorkerMain(), BackendPidGetProc(), BackendXidGetPid(), BecomeLockGroupLeader(), BecomeLockGroupMember(), BootStrapCLOG(), BootStrapMultiXact(), BootStrapSUBTRANS(), BufferAlloc(), CancelDBBackends(), check_for_freed_segments(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), choose_next_subplan_for_leader(), choose_next_subplan_for_worker(), CleanupInvalidationState(), ClearOldPredicateLocks(), clog_redo(), commit_ts_redo(), ComputeXidHorizons(), consume_xids_shortcut(), copy_replication_slot(), CountDBBackends(), CountDBConnections(), CountOtherDBBackends(), CountUserBackends(), CreateCheckPoint(), CreateEndOfRecoveryRecord(), CreateInitDecodingContext(), CreatePredicateLock(), CreateRestartPoint(), DeactivateCommitTs(), DeleteChildTargetLocks(), DeleteLockTarget(), destroy_superblock(), do_autovacuum(), do_pg_backup_start(), do_pg_backup_stop(), do_start_worker(), DropAllPredicateLocksFromTable(), DropSubscription(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), dsa_get_total_size(), dsa_pin(), dsa_release_in_place(), dsa_set_size_limit(), dsa_trim(), dsa_unpin(), dshash_delete_key(), dshash_dump(), dshash_find(), dshash_find_or_insert(), dshash_seq_next(), dsm_attach(), dsm_create(), dsm_detach(), dsm_pin_segment(), dsm_unpin_segment(), ensure_active_superblock(), entry_reset(), Exec_ListenPreCommit(), ExecParallelHashMergeCounters(), ExecParallelHashPopChunkQueue(), ExecParallelHashTupleAlloc(), ExecParallelHashTuplePrealloc(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendBufferedRelShared(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), FindAndDropRelationBuffers(), FinishPreparedTransaction(), FlushDatabaseBuffers(), FlushRelationBuffers(), FlushRelationsAllBuffers(), ForceTransactionIdLimitUpdate(), ForwardSyncRequest(), FreeWorkerInfo(), get_local_synced_slots(), get_val_in_shmem(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLeaderApplyWorkerPid(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldestUnsummarizedLSN(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionData(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetVirtualXIDsDelayingChkpt(), GetWaitEventExtensionIdentifier(), GetWaitEventExtensionNames(), GetWalSummarizerState(), HaveVirtualXIDsDelayingChkpt(), init_dsm_registry(), InjectionPointAttach(), InjectionPointDetach(), InjectionPointRun(), InstallXLogFileSegment(), InvalidateBuffer(), InvalidateObsoleteReplicationSlots(), InvalidatePossiblyObsoleteSlot(), InvalidateVictimBuffer(), IsInstallXLogFileSegmentActive(), KnownAssignedXidsCompress(), KnownAssignedXidsReset(), lock_twophase_recover(), LockAcquireExtended(), LockBuffer(), LockErrorCleanup(), LockGXact(), LockHasWaiters(), LockRefindAndRelease(), LockRelease(), LockReleaseAll(), LockWaiterCount(), logicalrep_launcher_attach_dshmem(), logicalrep_pa_worker_stop(), logicalrep_worker_attach(), logicalrep_worker_detach(), logicalrep_worker_launch(), logicalrep_worker_stop(), logicalrep_worker_stop_internal(), logicalrep_worker_wakeup(), LookupGXact(), MarkAsPrepared(), MarkAsPreparing(), MaybeExtendOffsetSlru(), multixact_redo(), MultiXactAdvanceNextMXact(), MultiXactGetCheckptMulti(), MultiXactIdSetOldestMember(), MultiXactIdSetOldestVisible(), MultiXactSetNextMXact(), PageIsPredicateLocked(), perform_relmap_update(), pg_control_checkpoint(), pg_control_init(), pg_control_recovery(), pg_control_system(), pg_get_replication_slots(), pg_get_shmem_allocations(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_statements_internal(), pg_xact_status(), pgss_shmem_startup(), pgss_store(), pgstat_archiver_reset_all_cb(), pgstat_archiver_snapshot_cb(), pgstat_bgwriter_reset_all_cb(), pgstat_bgwriter_snapshot_cb(), pgstat_build_snapshot(), pgstat_checkpointer_reset_all_cb(), pgstat_checkpointer_snapshot_cb(), pgstat_fetch_replslot(), pgstat_flush_io(), pgstat_flush_wal(), pgstat_io_reset_all_cb(), pgstat_io_snapshot_cb(), pgstat_lock_entry(), pgstat_lock_entry_shared(), pgstat_reset_matching_entries(), pgstat_reset_replslot(), pgstat_reset_slru_counter_internal(), pgstat_slru_flush(), pgstat_slru_snapshot_cb(), pgstat_wal_reset_all_cb(), pgstat_wal_snapshot_cb(), PostPrepare_Locks(), PostPrepare_MultiXact(), PostPrepare_Twophase(), PreCommit_CheckForSerializationFailure(), PreCommit_Notify(), predicatelock_twophase_recover(), PredicateLockPageSplit(), PredicateLockTwoPhaseFinish(), PrefetchSharedBuffer(), PrescanPreparedTransactions(), ProcArrayAdd(), ProcArrayApplyRecoveryInfo(), ProcArrayApplyXidAssignment(), ProcArrayClearTransaction(), ProcArrayEndTransaction(), ProcArrayGetReplicationSlotXmin(), ProcArrayGroupClearXid(), ProcArrayInstallImportedXmin(), ProcArrayInstallRestoredXmin(), ProcArrayRemove(), ProcArraySetReplicationSlotXmin(), process_syncing_tables_for_apply(), ProcKill(), ProcNumberGetTransactionIds(), ProcSleep(), ReachedEndOfBackup(), read_relmap_file(), ReadBuffer_common(), ReadMultiXactCounts(), ReadMultiXactIdRange(), ReadNextFullTransactionId(), ReadNextMultiXactId(), ReadReplicationSlot(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePreInvalidate(), RelationMapCopy(), RelationMapFinishBootstrap(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), relmap_redo(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquire(), ReplicationSlotCleanup(), ReplicationSlotCreate(), ReplicationSlotDropPtr(), ReplicationSlotName(), ReplicationSlotRelease(), ReplicationSlotsComputeLogicalRestartLSN(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotsCountDBSlots(), ReplicationSlotsDropDBSlots(), replorigin_advance(), replorigin_get_progress(), replorigin_session_advance(), replorigin_session_get_progress(), replorigin_session_reset(), replorigin_session_setup(), replorigin_state_clear(), resize(), RestoreScratchTarget(), restoreTwoPhaseData(), SaveSlotToPath(), SearchNamedReplicationSlot(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), SerialInit(), SerialSetActiveSerXmin(), set_indexsafe_procflags(), set_val_in_shmem(), SetCommitTsLimit(), SetInstallXLogFileSegmentActive(), SetMultiXactIdLimit(), SetNextObjectId(), SetOffsetVacuumLimit(), SetTransactionIdLimit(), SetWalSummarizerLatch(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SignalVirtualTransaction(), SIInsertDataEntries(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SimpleLruWriteAll(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), StandbyRecoverPreparedTransactions(), StandbySlotsHaveCaughtup(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), sts_parallel_scan_next(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SummarizeWAL(), SwitchIntoArchiveRecovery(), synchronize_one_slot(), SyncOneBuffer(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateOtherDBBackends(), test_slru_page_exists(), test_slru_page_read(), test_slru_page_write(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), TwoPhaseGetXidByVirtualXID(), update_cached_xid_range(), UpdateMinRecoveryPoint(), vac_truncate_clog(), vacuum_rel(), VacuumUpdateCosts(), validate_standby_slots(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_relation_state_change(), wait_for_worker_state_change(), WaitEventExtensionNew(), WaitForReplicationWorkerAttach(), WaitForWalSummarization(), WALInsertLockAcquire(), WALInsertLockAcquireExclusive(), WalSummarizerMain(), WalSummarizerShutdown(), write_relcache_init_file(), xact_redo(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), XLogReportParameters(), and XLogShutdownWalRcv().

◆ LWLockAcquireOrWait()

bool LWLockAcquireOrWait ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1400 of file lwlock.c.

1401 {
1402  PGPROC *proc = MyProc;
1403  bool mustwait;
1404  int extraWaits = 0;
1405 #ifdef LWLOCK_STATS
1406  lwlock_stats *lwstats;
1407 
1408  lwstats = get_lwlock_stats_entry(lock);
1409 #endif
1410 
1412 
1413  PRINT_LWDEBUG("LWLockAcquireOrWait", lock, mode);
1414 
1415  /* Ensure we will have room to remember the lock */
1417  elog(ERROR, "too many LWLocks taken");
1418 
1419  /*
1420  * Lock out cancel/die interrupts until we exit the code section protected
1421  * by the LWLock. This ensures that interrupts will not interfere with
1422  * manipulations of data structures in shared memory.
1423  */
1424  HOLD_INTERRUPTS();
1425 
1426  /*
1427  * NB: We're using nearly the same twice-in-a-row lock acquisition
1428  * protocol as LWLockAcquire(). Check its comments for details.
1429  */
1430  mustwait = LWLockAttemptLock(lock, mode);
1431 
1432  if (mustwait)
1433  {
1435 
1436  mustwait = LWLockAttemptLock(lock, mode);
1437 
1438  if (mustwait)
1439  {
1440  /*
1441  * Wait until awakened. Like in LWLockAcquire, be prepared for
1442  * bogus wakeups.
1443  */
1444  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "waiting");
1445 
1446 #ifdef LWLOCK_STATS
1447  lwstats->block_count++;
1448 #endif
1449 
1450  LWLockReportWaitStart(lock);
1451  if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED())
1452  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1453 
1454  for (;;)
1455  {
1456  PGSemaphoreLock(proc->sem);
1457  if (proc->lwWaiting == LW_WS_NOT_WAITING)
1458  break;
1459  extraWaits++;
1460  }
1461 
1462 #ifdef LOCK_DEBUG
1463  {
1464  /* not waiting anymore */
1465  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1466 
1467  Assert(nwaiters < MAX_BACKENDS);
1468  }
1469 #endif
1470  if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED())
1471  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1473 
1474  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "awakened");
1475  }
1476  else
1477  {
1478  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "acquired, undoing queue");
1479 
1480  /*
1481  * Got lock in the second attempt, undo queueing. We need to treat
1482  * this as having successfully acquired the lock, otherwise we'd
1483  * not necessarily wake up people we've prevented from acquiring
1484  * the lock.
1485  */
1486  LWLockDequeueSelf(lock);
1487  }
1488  }
1489 
1490  /*
1491  * Fix the process wait semaphore's count for any absorbed wakeups.
1492  */
1493  while (extraWaits-- > 0)
1494  PGSemaphoreUnlock(proc->sem);
1495 
1496  if (mustwait)
1497  {
1498  /* Failed to get lock, so release interrupt holdoff */
1500  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "failed");
1501  if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL_ENABLED())
1502  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode);
1503  }
1504  else
1505  {
1506  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "succeeded");
1507  /* Add lock to list of locks held by this backend */
1510  if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_ENABLED())
1511  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode);
1512  }
1513 
1514  return !mustwait;
1515 }
@ LW_WAIT_UNTIL_FREE
Definition: lwlock.h:118
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:135

References Assert(), elog, ERROR, held_lwlocks, HOLD_INTERRUPTS, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_SHARED, LW_WAIT_UNTIL_FREE, LW_WS_NOT_WAITING, LWLockAttemptLock(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MAX_SIMUL_LWLOCKS, LWLockHandle::mode, mode, MyProc, num_held_lwlocks, pg_atomic_fetch_sub_u32(), PG_USED_FOR_ASSERTS_ONLY, PGSemaphoreLock(), PGSemaphoreUnlock(), PRINT_LWDEBUG, RESUME_INTERRUPTS, PGPROC::sem, and T_NAME.

Referenced by XLogFlush().

◆ LWLockAnyHeldByMe()

bool LWLockAnyHeldByMe ( LWLock lock,
int  nlocks,
size_t  stride 
)

Definition at line 1915 of file lwlock.c.

1916 {
1917  char *held_lock_addr;
1918  char *begin;
1919  char *end;
1920  int i;
1921 
1922  begin = (char *) lock;
1923  end = begin + nlocks * stride;
1924  for (i = 0; i < num_held_lwlocks; i++)
1925  {
1926  held_lock_addr = (char *) held_lwlocks[i].lock;
1927  if (held_lock_addr >= begin &&
1928  held_lock_addr < end &&
1929  (held_lock_addr - begin) % stride == 0)
1930  return true;
1931  }
1932  return false;
1933 }

References held_lwlocks, i, and num_held_lwlocks.

◆ LWLockAttemptLock()

static bool LWLockAttemptLock ( LWLock lock,
LWLockMode  mode 
)
static

Definition at line 788 of file lwlock.c.

789 {
790  uint32 old_state;
791 
793 
794  /*
795  * Read once outside the loop, later iterations will get the newer value
796  * via compare & exchange.
797  */
798  old_state = pg_atomic_read_u32(&lock->state);
799 
800  /* loop until we've determined whether we could acquire the lock or not */
801  while (true)
802  {
803  uint32 desired_state;
804  bool lock_free;
805 
806  desired_state = old_state;
807 
808  if (mode == LW_EXCLUSIVE)
809  {
810  lock_free = (old_state & LW_LOCK_MASK) == 0;
811  if (lock_free)
812  desired_state += LW_VAL_EXCLUSIVE;
813  }
814  else
815  {
816  lock_free = (old_state & LW_VAL_EXCLUSIVE) == 0;
817  if (lock_free)
818  desired_state += LW_VAL_SHARED;
819  }
820 
821  /*
822  * Attempt to swap in the state we are expecting. If we didn't see
823  * lock to be free, that's just the old value. If we saw it as free,
824  * we'll attempt to mark it acquired. The reason that we always swap
825  * in the value is that this doubles as a memory barrier. We could try
826  * to be smarter and only swap in values if we saw the lock as free,
827  * but benchmark haven't shown it as beneficial so far.
828  *
829  * Retry if the value changed since we last looked at it.
830  */
832  &old_state, desired_state))
833  {
834  if (lock_free)
835  {
836  /* Great! Got the lock. */
837 #ifdef LOCK_DEBUG
838  if (mode == LW_EXCLUSIVE)
839  lock->owner = MyProc;
840 #endif
841  return false;
842  }
843  else
844  return true; /* somebody else has the lock */
845  }
846  }
847  pg_unreachable();
848 }
static bool pg_atomic_compare_exchange_u32(volatile pg_atomic_uint32 *ptr, uint32 *expected, uint32 newval)
Definition: atomics.h:344
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:234
#define pg_unreachable()
Definition: c.h:283
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:101
#define LW_VAL_SHARED
Definition: lwlock.c:102
#define LW_LOCK_MASK
Definition: lwlock.c:104

References Assert(), LW_EXCLUSIVE, LW_LOCK_MASK, LW_SHARED, LW_VAL_EXCLUSIVE, LW_VAL_SHARED, mode, MyProc, pg_atomic_compare_exchange_u32(), pg_atomic_read_u32(), pg_unreachable, and LWLock::state.

Referenced by LWLockAcquire(), LWLockAcquireOrWait(), and LWLockConditionalAcquire().

◆ LWLockConditionalAcquire()

bool LWLockConditionalAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1343 of file lwlock.c.

1344 {
1345  bool mustwait;
1346 
1348 
1349  PRINT_LWDEBUG("LWLockConditionalAcquire", lock, mode);
1350 
1351  /* Ensure we will have room to remember the lock */
1353  elog(ERROR, "too many LWLocks taken");
1354 
1355  /*
1356  * Lock out cancel/die interrupts until we exit the code section protected
1357  * by the LWLock. This ensures that interrupts will not interfere with
1358  * manipulations of data structures in shared memory.
1359  */
1360  HOLD_INTERRUPTS();
1361 
1362  /* Check for the lock */
1363  mustwait = LWLockAttemptLock(lock, mode);
1364 
1365  if (mustwait)
1366  {
1367  /* Failed to get lock, so release interrupt holdoff */
1369 
1370  LOG_LWDEBUG("LWLockConditionalAcquire", lock, "failed");
1371  if (TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL_ENABLED())
1372  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode);
1373  }
1374  else
1375  {
1376  /* Add lock to list of locks held by this backend */
1379  if (TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_ENABLED())
1380  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode);
1381  }
1382  return !mustwait;
1383 }

References Assert(), elog, ERROR, held_lwlocks, HOLD_INTERRUPTS, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_SHARED, LWLockAttemptLock(), MAX_SIMUL_LWLOCKS, LWLockHandle::mode, mode, num_held_lwlocks, PRINT_LWDEBUG, RESUME_INTERRUPTS, and T_NAME.

Referenced by ConditionalLockBuffer(), GetVictimBuffer(), pgstat_flush_io(), pgstat_flush_wal(), pgstat_lock_entry(), pgstat_lock_entry_shared(), pgstat_slru_flush(), ProcArrayEndTransaction(), SimpleLruWaitIO(), ss_report_location(), TransactionIdSetPageStatus(), and XLogNeedsFlush().

◆ LWLockConflictsWithVar()

static bool LWLockConflictsWithVar ( LWLock lock,
pg_atomic_uint64 valptr,
uint64  oldval,
uint64 *  newval,
bool result 
)
static

Definition at line 1527 of file lwlock.c.

1529 {
1530  bool mustwait;
1531  uint64 value;
1532 
1533  /*
1534  * Test first to see if it the slot is free right now.
1535  *
1536  * XXX: the unique caller of this routine, WaitXLogInsertionsToFinish()
1537  * via LWLockWaitForVar(), uses an implied barrier with a spinlock before
1538  * this, so we don't need a memory barrier here as far as the current
1539  * usage is concerned. But that might not be safe in general.
1540  */
1541  mustwait = (pg_atomic_read_u32(&lock->state) & LW_VAL_EXCLUSIVE) != 0;
1542 
1543  if (!mustwait)
1544  {
1545  *result = true;
1546  return false;
1547  }
1548 
1549  *result = false;
1550 
1551  /*
1552  * Reading this value atomically is safe even on platforms where uint64
1553  * cannot be read without observing a torn value.
1554  */
1555  value = pg_atomic_read_u64(valptr);
1556 
1557  if (value != oldval)
1558  {
1559  mustwait = false;
1560  *newval = value;
1561  }
1562  else
1563  {
1564  mustwait = true;
1565  }
1566 
1567  return mustwait;
1568 }
static uint64 pg_atomic_read_u64(volatile pg_atomic_uint64 *ptr)
Definition: atomics.h:462
#define newval
static struct @150 value

References LW_VAL_EXCLUSIVE, newval, pg_atomic_read_u32(), pg_atomic_read_u64(), LWLock::state, and value.

Referenced by LWLockWaitForVar().

◆ LWLockDequeueSelf()

static void LWLockDequeueSelf ( LWLock lock)
static

Definition at line 1083 of file lwlock.c.

1084 {
1085  bool on_waitlist;
1086 
1087 #ifdef LWLOCK_STATS
1088  lwlock_stats *lwstats;
1089 
1090  lwstats = get_lwlock_stats_entry(lock);
1091 
1092  lwstats->dequeue_self_count++;
1093 #endif
1094 
1095  LWLockWaitListLock(lock);
1096 
1097  /*
1098  * Remove ourselves from the waitlist, unless we've already been removed.
1099  * The removal happens with the wait list lock held, so there's no race in
1100  * this check.
1101  */
1102  on_waitlist = MyProc->lwWaiting == LW_WS_WAITING;
1103  if (on_waitlist)
1104  proclist_delete(&lock->waiters, MyProcNumber, lwWaitLink);
1105 
1106  if (proclist_is_empty(&lock->waiters) &&
1107  (pg_atomic_read_u32(&lock->state) & LW_FLAG_HAS_WAITERS) != 0)
1108  {
1110  }
1111 
1112  /* XXX: combine with fetch_and above? */
1113  LWLockWaitListUnlock(lock);
1114 
1115  /* clear waiting state again, nice for debugging */
1116  if (on_waitlist)
1118  else
1119  {
1120  int extraWaits = 0;
1121 
1122  /*
1123  * Somebody else dequeued us and has or will wake us up. Deal with the
1124  * superfluous absorption of a wakeup.
1125  */
1126 
1127  /*
1128  * Reset RELEASE_OK flag if somebody woke us before we removed
1129  * ourselves - they'll have set it to false.
1130  */
1132 
1133  /*
1134  * Now wait for the scheduled wakeup, otherwise our ->lwWaiting would
1135  * get reset at some inconvenient point later. Most of the time this
1136  * will immediately return.
1137  */
1138  for (;;)
1139  {
1142  break;
1143  extraWaits++;
1144  }
1145 
1146  /*
1147  * Fix the process wait semaphore's count for any absorbed wakeups.
1148  */
1149  while (extraWaits-- > 0)
1151  }
1152 
1153 #ifdef LOCK_DEBUG
1154  {
1155  /* not waiting anymore */
1156  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1157 
1158  Assert(nwaiters < MAX_BACKENDS);
1159  }
1160 #endif
1161 }
static uint32 pg_atomic_fetch_and_u32(volatile pg_atomic_uint32 *ptr, uint32 and_)
Definition: atomics.h:391
ProcNumber MyProcNumber
Definition: globals.c:87
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:859
#define LW_FLAG_HAS_WAITERS
Definition: lwlock.c:97
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:911
@ LW_WS_WAITING
Definition: lwlock.h:30
#define proclist_delete(list, procno, link_member)
Definition: proclist.h:187
static bool proclist_is_empty(const proclist_head *list)
Definition: proclist.h:38
proclist_head waiters
Definition: lwlock.h:44

References Assert(), LW_FLAG_HAS_WAITERS, LW_FLAG_RELEASE_OK, LW_WS_NOT_WAITING, LW_WS_WAITING, LWLockWaitListLock(), LWLockWaitListUnlock(), PGPROC::lwWaiting, MAX_BACKENDS, MyProc, MyProcNumber, pg_atomic_fetch_and_u32(), pg_atomic_fetch_or_u32(), pg_atomic_fetch_sub_u32(), pg_atomic_read_u32(), PG_USED_FOR_ASSERTS_ONLY, PGSemaphoreLock(), PGSemaphoreUnlock(), proclist_delete, proclist_is_empty(), PGPROC::sem, LWLock::state, and LWLock::waiters.

Referenced by LWLockAcquire(), LWLockAcquireOrWait(), and LWLockWaitForVar().

◆ LWLockHeldByMe()

◆ LWLockHeldByMeInMode()

◆ LWLockInitialize()

void LWLockInitialize ( LWLock lock,
int  tranche_id 
)

Definition at line 707 of file lwlock.c.

708 {
710 #ifdef LOCK_DEBUG
711  pg_atomic_init_u32(&lock->nwaiters, 0);
712 #endif
713  lock->tranche = tranche_id;
714  proclist_init(&lock->waiters);
715 }
static void pg_atomic_init_u32(volatile pg_atomic_uint32 *ptr, uint32 val)
Definition: atomics.h:216
static void proclist_init(proclist_head *list)
Definition: proclist.h:29
uint16 tranche
Definition: lwlock.h:42

References LW_FLAG_RELEASE_OK, pg_atomic_init_u32(), proclist_init(), LWLock::state, LWLock::tranche, and LWLock::waiters.

Referenced by apw_init_state(), create_internal(), dshash_create(), ExecAppendInitializeDSM(), ExecHashJoinInitializeDSM(), InitBufferPool(), InitializeLWLocks(), InitPredicateLocks(), InitProcGlobal(), pgstat_init_entry(), ReplicationOriginShmemInit(), ReplicationSlotsShmemInit(), SimpleLruInit(), StatsShmemInit(), sts_initialize(), tbm_prepare_shared_iterate(), tdr_init_shmem(), and XLOGShmemInit().

◆ LWLockNewTrancheId()

int LWLockNewTrancheId ( void  )

Definition at line 604 of file lwlock.c.

605 {
606  int result;
607  int *LWLockCounter;
608 
609  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
611  result = (*LWLockCounter)++;
613 
614  return result;
615 }
slock_t * ShmemLock
Definition: shmem.c:87
#define SpinLockRelease(lock)
Definition: spin.h:64
#define SpinLockAcquire(lock)
Definition: spin.h:62

References MainLWLockArray, ShmemLock, SpinLockAcquire, and SpinLockRelease.

Referenced by apw_init_state(), InitializeLWLocks(), tdr_init_shmem(), test_basic(), test_dsa_basic(), test_dsa_resowners(), test_empty(), test_random(), and test_slru_shmem_startup().

◆ LWLockQueueSelf()

static void LWLockQueueSelf ( LWLock lock,
LWLockMode  mode 
)
static

Definition at line 1040 of file lwlock.c.

1041 {
1042  /*
1043  * If we don't have a PGPROC structure, there's no way to wait. This
1044  * should never occur, since MyProc should only be null during shared
1045  * memory initialization.
1046  */
1047  if (MyProc == NULL)
1048  elog(PANIC, "cannot wait without a PGPROC structure");
1049 
1051  elog(PANIC, "queueing for lock while waiting on another one");
1052 
1053  LWLockWaitListLock(lock);
1054 
1055  /* setting the flag is protected by the spinlock */
1057 
1059  MyProc->lwWaitMode = mode;
1060 
1061  /* LW_WAIT_UNTIL_FREE waiters are always at the front of the queue */
1062  if (mode == LW_WAIT_UNTIL_FREE)
1063  proclist_push_head(&lock->waiters, MyProcNumber, lwWaitLink);
1064  else
1065  proclist_push_tail(&lock->waiters, MyProcNumber, lwWaitLink);
1066 
1067  /* Can release the mutex now */
1068  LWLockWaitListUnlock(lock);
1069 
1070 #ifdef LOCK_DEBUG
1071  pg_atomic_fetch_add_u32(&lock->nwaiters, 1);
1072 #endif
1073 }
static uint32 pg_atomic_fetch_add_u32(volatile pg_atomic_uint32 *ptr, int32 add_)
Definition: atomics.h:361
#define PANIC
Definition: elog.h:42
#define proclist_push_tail(list, procno, link_member)
Definition: proclist.h:191
#define proclist_push_head(list, procno, link_member)
Definition: proclist.h:189
uint8 lwWaitMode
Definition: proc.h:220

References elog, LW_FLAG_HAS_WAITERS, LW_WAIT_UNTIL_FREE, LW_WS_NOT_WAITING, LW_WS_WAITING, LWLockWaitListLock(), LWLockWaitListUnlock(), PGPROC::lwWaiting, PGPROC::lwWaitMode, mode, MyProc, MyProcNumber, PANIC, pg_atomic_fetch_add_u32(), pg_atomic_fetch_or_u32(), proclist_push_head, proclist_push_tail, LWLock::state, and LWLock::waiters.

Referenced by LWLockAcquire(), LWLockAcquireOrWait(), and LWLockWaitForVar().

◆ LWLockRegisterTranche()

void LWLockRegisterTranche ( int  tranche_id,
const char *  tranche_name 
)

Definition at line 628 of file lwlock.c.

629 {
630  /* This should only be called for user-defined tranches. */
631  if (tranche_id < LWTRANCHE_FIRST_USER_DEFINED)
632  return;
633 
634  /* Convert to array index. */
635  tranche_id -= LWTRANCHE_FIRST_USER_DEFINED;
636 
637  /* If necessary, create or enlarge array. */
638  if (tranche_id >= LWLockTrancheNamesAllocated)
639  {
640  int newalloc;
641 
642  newalloc = pg_nextpower2_32(Max(8, tranche_id + 1));
643 
644  if (LWLockTrancheNames == NULL)
645  LWLockTrancheNames = (const char **)
647  newalloc * sizeof(char *));
648  else
651  LWLockTrancheNamesAllocated = newalloc;
652  }
653 
654  LWLockTrancheNames[tranche_id] = tranche_name;
655 }
#define Max(x, y)
Definition: c.h:985
MemoryContext TopMemoryContext
Definition: mcxt.c:137
void * MemoryContextAllocZero(MemoryContext context, Size size)
Definition: mcxt.c:1202
#define repalloc0_array(pointer, type, oldcount, count)
Definition: palloc.h:109
static uint32 pg_nextpower2_32(uint32 num)
Definition: pg_bitutils.h:189

References LWLockTrancheNames, LWLockTrancheNamesAllocated, LWTRANCHE_FIRST_USER_DEFINED, Max, MemoryContextAllocZero(), pg_nextpower2_32(), repalloc0_array, and TopMemoryContext.

Referenced by apw_init_shmem(), CreateLWLocks(), tdr_attach_shmem(), test_basic(), test_dsa_basic(), test_dsa_resowners(), test_empty(), test_random(), and test_slru_shmem_startup().

◆ LWLockRelease()

void LWLockRelease ( LWLock lock)

Definition at line 1785 of file lwlock.c.

1786 {
1787  LWLockMode mode;
1788  uint32 oldstate;
1789  bool check_waiters;
1790  int i;
1791 
1792  /*
1793  * Remove lock from list of locks held. Usually, but not always, it will
1794  * be the latest-acquired lock; so search array backwards.
1795  */
1796  for (i = num_held_lwlocks; --i >= 0;)
1797  if (lock == held_lwlocks[i].lock)
1798  break;
1799 
1800  if (i < 0)
1801  elog(ERROR, "lock %s is not held", T_NAME(lock));
1802 
1803  mode = held_lwlocks[i].mode;
1804 
1805  num_held_lwlocks--;
1806  for (; i < num_held_lwlocks; i++)
1807  held_lwlocks[i] = held_lwlocks[i + 1];
1808 
1809  PRINT_LWDEBUG("LWLockRelease", lock, mode);
1810 
1811  /*
1812  * Release my hold on lock, after that it can immediately be acquired by
1813  * others, even if we still have to wakeup other waiters.
1814  */
1815  if (mode == LW_EXCLUSIVE)
1816  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_EXCLUSIVE);
1817  else
1818  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_SHARED);
1819 
1820  /* nobody else can have that kind of lock */
1821  Assert(!(oldstate & LW_VAL_EXCLUSIVE));
1822 
1823  if (TRACE_POSTGRESQL_LWLOCK_RELEASE_ENABLED())
1824  TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
1825 
1826  /*
1827  * We're still waiting for backends to get scheduled, don't wake them up
1828  * again.
1829  */
1830  if ((oldstate & (LW_FLAG_HAS_WAITERS | LW_FLAG_RELEASE_OK)) ==
1832  (oldstate & LW_LOCK_MASK) == 0)
1833  check_waiters = true;
1834  else
1835  check_waiters = false;
1836 
1837  /*
1838  * As waking up waiters requires the spinlock to be acquired, only do so
1839  * if necessary.
1840  */
1841  if (check_waiters)
1842  {
1843  /* XXX: remove before commit? */
1844  LOG_LWDEBUG("LWLockRelease", lock, "releasing waiters");
1845  LWLockWakeup(lock);
1846  }
1847 
1848  /*
1849  * Now okay to allow cancel/die interrupts.
1850  */
1852 }
static uint32 pg_atomic_sub_fetch_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:434
static void LWLockWakeup(LWLock *lock)
Definition: lwlock.c:924
LWLockMode
Definition: lwlock.h:115

References Assert(), elog, ERROR, held_lwlocks, i, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_HAS_WAITERS, LW_FLAG_RELEASE_OK, LW_LOCK_MASK, LW_VAL_EXCLUSIVE, LW_VAL_SHARED, LWLockWakeup(), LWLockHandle::mode, mode, num_held_lwlocks, pg_atomic_sub_fetch_u32(), PRINT_LWDEBUG, RESUME_INTERRUPTS, LWLock::state, and T_NAME.

Referenced by _bt_end_vacuum(), _bt_start_vacuum(), _bt_vacuum_cycleid(), AbsorbSyncRequests(), ActivateCommitTs(), AdjustToFullTransactionId(), AdvanceNextFullTransactionIdPastXid(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_load_buffers(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AtAbort_Twophase(), AtEOXact_LogicalRepWorkers(), AtPrepare_PredicateLocks(), attach_internal(), autoprewarm_main(), autoprewarm_start_worker(), AutoVacuumRequestWork(), AutoVacWorkerMain(), BackendPidGetProc(), BackendXidGetPid(), BecomeLockGroupLeader(), BecomeLockGroupMember(), BootStrapCLOG(), BootStrapMultiXact(), BootStrapSUBTRANS(), BufferAlloc(), CancelDBBackends(), check_for_freed_segments(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), choose_next_subplan_for_leader(), choose_next_subplan_for_worker(), CleanupInvalidationState(), ClearOldPredicateLocks(), clog_redo(), commit_ts_redo(), ComputeXidHorizons(), consume_xids_shortcut(), copy_replication_slot(), CountDBBackends(), CountDBConnections(), CountOtherDBBackends(), CountUserBackends(), CreateCheckPoint(), CreateEndOfRecoveryRecord(), CreateInitDecodingContext(), CreatePredicateLock(), CreateRestartPoint(), DeactivateCommitTs(), DeleteChildTargetLocks(), DeleteLockTarget(), destroy_superblock(), do_autovacuum(), do_pg_backup_start(), do_pg_backup_stop(), do_start_worker(), DropAllPredicateLocksFromTable(), DropSubscription(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), dsa_get_total_size(), dsa_pin(), dsa_release_in_place(), dsa_set_size_limit(), dsa_trim(), dsa_unpin(), dshash_delete_entry(), dshash_delete_key(), dshash_dump(), dshash_find(), dshash_find_or_insert(), dshash_release_lock(), dshash_seq_next(), dshash_seq_term(), dsm_attach(), dsm_create(), dsm_detach(), dsm_pin_segment(), dsm_unpin_segment(), ensure_active_superblock(), entry_reset(), Exec_ListenPreCommit(), ExecParallelHashMergeCounters(), ExecParallelHashPopChunkQueue(), ExecParallelHashTupleAlloc(), ExecParallelHashTuplePrealloc(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendBufferedRelShared(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), find_multixact_start(), FindAndDropRelationBuffers(), FinishPreparedTransaction(), FlushDatabaseBuffers(), FlushRelationBuffers(), FlushRelationsAllBuffers(), ForceTransactionIdLimitUpdate(), ForwardSyncRequest(), FreeWorkerInfo(), get_local_synced_slots(), get_val_in_shmem(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLeaderApplyWorkerPid(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldestUnsummarizedLSN(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetStrictOldestNonRemovableTransactionId(), GetVictimBuffer(), GetVirtualXIDsDelayingChkpt(), GetWaitEventExtensionIdentifier(), GetWaitEventExtensionNames(), GetWalSummarizerState(), HaveVirtualXIDsDelayingChkpt(), init_dsm_registry(), InjectionPointAttach(), InjectionPointDetach(), InjectionPointRun(), InstallXLogFileSegment(), InvalidateBuffer(), InvalidateObsoleteReplicationSlots(), InvalidatePossiblyObsoleteSlot(), InvalidateVictimBuffer(), IsInstallXLogFileSegmentActive(), KnownAssignedXidsCompress(), KnownAssignedXidsReset(), lock_twophase_recover(), LockAcquireExtended(), LockBuffer(), LockErrorCleanup(), LockGXact(), LockHasWaiters(), LockRefindAndRelease(), LockRelease(), LockReleaseAll(), LockWaiterCount(), logicalrep_launcher_attach_dshmem(), logicalrep_pa_worker_stop(), logicalrep_worker_attach(), logicalrep_worker_detach(), logicalrep_worker_launch(), logicalrep_worker_stop(), logicalrep_worker_stop_internal(), logicalrep_worker_wakeup(), LogStandbySnapshot(), LookupGXact(), LWLockReleaseAll(), LWLockReleaseClearVar(), MarkAsPrepared(), MarkAsPreparing(), MaybeExtendOffsetSlru(), multixact_redo(), MultiXactAdvanceNextMXact(), MultiXactGetCheckptMulti(), MultiXactIdSetOldestMember(), MultiXactIdSetOldestVisible(), MultiXactSetNextMXact(), OnConflict_CheckForSerializationFailure(), PageIsPredicateLocked(), perform_relmap_update(), pg_control_checkpoint(), pg_control_init(), pg_control_recovery(), pg_control_system(), pg_get_replication_slots(), pg_get_shmem_allocations(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_statements_internal(), pg_xact_status(), pgss_shmem_startup(), pgss_store(), pgstat_archiver_reset_all_cb(), pgstat_archiver_snapshot_cb(), pgstat_bgwriter_reset_all_cb(), pgstat_bgwriter_snapshot_cb(), pgstat_build_snapshot(), pgstat_checkpointer_reset_all_cb(), pgstat_checkpointer_snapshot_cb(), pgstat_fetch_replslot(), pgstat_flush_io(), pgstat_flush_wal(), pgstat_io_reset_all_cb(), pgstat_io_snapshot_cb(), pgstat_reset_matching_entries(), pgstat_reset_replslot(), pgstat_reset_slru_counter_internal(), pgstat_slru_flush(), pgstat_slru_snapshot_cb(), pgstat_unlock_entry(), pgstat_wal_reset_all_cb(), pgstat_wal_snapshot_cb(), PostPrepare_Locks(), PostPrepare_MultiXact(), PostPrepare_Twophase(), PreCommit_CheckForSerializationFailure(), PreCommit_Notify(), predicatelock_twophase_recover(), PredicateLockPageSplit(), PredicateLockTwoPhaseFinish(), PrefetchSharedBuffer(), PrescanPreparedTransactions(), ProcArrayAdd(), ProcArrayApplyRecoveryInfo(), ProcArrayApplyXidAssignment(), ProcArrayClearTransaction(), ProcArrayEndTransaction(), ProcArrayGetReplicationSlotXmin(), ProcArrayGroupClearXid(), ProcArrayInstallImportedXmin(), ProcArrayInstallRestoredXmin(), ProcArrayRemove(), ProcArraySetReplicationSlotXmin(), process_syncing_tables_for_apply(), ProcKill(), ProcNumberGetTransactionIds(), ProcSleep(), ReachedEndOfBackup(), read_relmap_file(), ReadMultiXactCounts(), ReadMultiXactIdRange(), ReadNextFullTransactionId(), ReadNextMultiXactId(), ReadReplicationSlot(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePostInvalidate(), RelationMapCopy(), RelationMapFinishBootstrap(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), relmap_redo(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquire(), ReplicationSlotCleanup(), ReplicationSlotCreate(), ReplicationSlotDropPtr(), ReplicationSlotName(), ReplicationSlotRelease(), ReplicationSlotsComputeLogicalRestartLSN(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotsCountDBSlots(), ReplicationSlotsDropDBSlots(), replorigin_advance(), replorigin_get_progress(), replorigin_session_advance(), replorigin_session_get_progress(), replorigin_session_reset(), replorigin_session_setup(), replorigin_state_clear(), resize(), RestoreScratchTarget(), restoreTwoPhaseData(), SaveSlotToPath(), SearchNamedReplicationSlot(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), SerialInit(), SerialSetActiveSerXmin(), set_indexsafe_procflags(), set_val_in_shmem(), SetCommitTsLimit(), SetInstallXLogFileSegmentActive(), SetMultiXactIdLimit(), SetNextObjectId(), SetOffsetVacuumLimit(), SetTransactionIdLimit(), SetWalSummarizerLatch(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SignalVirtualTransaction(), SIInsertDataEntries(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SimpleLruWriteAll(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), ss_report_location(), StandbyRecoverPreparedTransactions(), StandbySlotsHaveCaughtup(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), sts_parallel_scan_next(), SubTransGetParent(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SummarizeWAL(), SwitchIntoArchiveRecovery(), synchronize_one_slot(), SyncOneBuffer(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateOtherDBBackends(), test_slru_page_exists(), test_slru_page_read(), test_slru_page_readonly(), test_slru_page_write(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdGetStatus(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), TwoPhaseGetXidByVirtualXID(), update_cached_xid_range(), UpdateMinRecoveryPoint(), vac_truncate_clog(), vacuum_rel(), VacuumUpdateCosts(), validate_standby_slots(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_relation_state_change(), wait_for_worker_state_change(), WaitEventExtensionNew(), WaitForReplicationWorkerAttach(), WaitForWalSummarization(), WaitOnLock(), WalSummarizerMain(), WalSummarizerShutdown(), write_relcache_init_file(), xact_redo(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), XLogFlush(), XLogNeedsFlush(), XLogReportParameters(), and XLogShutdownWalRcv().

◆ LWLockReleaseAll()

void LWLockReleaseAll ( void  )

Definition at line 1880 of file lwlock.c.

1881 {
1882  while (num_held_lwlocks > 0)
1883  {
1884  HOLD_INTERRUPTS(); /* match the upcoming RESUME_INTERRUPTS */
1885 
1887  }
1888 }
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1785

References held_lwlocks, HOLD_INTERRUPTS, LWLockRelease(), and num_held_lwlocks.

Referenced by AbortSubTransaction(), AbortTransaction(), AuxiliaryProcKill(), BackgroundWriterMain(), CheckpointerMain(), ProcKill(), ShutdownAuxiliaryProcess(), WalSndErrorCleanup(), WalSummarizerMain(), and WalWriterMain().

◆ LWLockReleaseClearVar()

void LWLockReleaseClearVar ( LWLock lock,
pg_atomic_uint64 valptr,
uint64  val 
)

Definition at line 1858 of file lwlock.c.

1859 {
1860  /*
1861  * Note that pg_atomic_exchange_u64 is a full barrier, so we're guaranteed
1862  * that the variable is updated before releasing the lock.
1863  */
1864  pg_atomic_exchange_u64(valptr, val);
1865 
1866  LWLockRelease(lock);
1867 }
static uint64 pg_atomic_exchange_u64(volatile pg_atomic_uint64 *ptr, uint64 newval)
Definition: atomics.h:498
long val
Definition: informix.c:664

References LWLockRelease(), pg_atomic_exchange_u64(), and val.

Referenced by WALInsertLockRelease().

◆ LWLockReportWaitEnd()

static void LWLockReportWaitEnd ( void  )
inlinestatic

Definition at line 734 of file lwlock.c.

735 {
737 }
static void pgstat_report_wait_end(void)
Definition: wait_event.h:104

References pgstat_report_wait_end().

Referenced by LWLockAcquire(), LWLockAcquireOrWait(), and LWLockWaitForVar().

◆ LWLockReportWaitStart()

static void LWLockReportWaitStart ( LWLock lock)
inlinestatic

Definition at line 725 of file lwlock.c.

726 {
728 }
static void pgstat_report_wait_start(uint32 wait_event_info)
Definition: wait_event.h:88

References PG_WAIT_LWLOCK, pgstat_report_wait_start(), and LWLock::tranche.

Referenced by LWLockAcquire(), LWLockAcquireOrWait(), and LWLockWaitForVar().

◆ LWLockShmemSize()

Size LWLockShmemSize ( void  )

Definition at line 421 of file lwlock.c.

422 {
423  Size size;
424  int i;
425  int numLocks = NUM_FIXED_LWLOCKS;
426 
427  /* Calculate total number of locks needed in the main array. */
428  numLocks += NumLWLocksForNamedTranches();
429 
430  /* Space for the LWLock array. */
431  size = mul_size(numLocks, sizeof(LWLockPadded));
432 
433  /* Space for dynamic allocation counter, plus room for alignment. */
434  size = add_size(size, sizeof(int) + LWLOCK_PADDED_SIZE);
435 
436  /* space for named tranches. */
438 
439  /* space for name of each tranche. */
440  for (i = 0; i < NamedLWLockTrancheRequests; i++)
441  size = add_size(size, strlen(NamedLWLockTrancheRequestArray[i].tranche_name) + 1);
442 
443  return size;
444 }
Size add_size(Size s1, Size s2)
Definition: shmem.c:493
Size mul_size(Size s1, Size s2)
Definition: shmem.c:510
static pg_noinline void Size size
Definition: slab.c:607

References add_size(), i, LWLOCK_PADDED_SIZE, mul_size(), NamedLWLockTrancheRequestArray, NamedLWLockTrancheRequests, NUM_FIXED_LWLOCKS, NumLWLocksForNamedTranches(), and size.

Referenced by CalculateShmemSize(), and CreateLWLocks().

◆ LWLockUpdateVar()

void LWLockUpdateVar ( LWLock lock,
pg_atomic_uint64 valptr,
uint64  val 
)

Definition at line 1724 of file lwlock.c.

1725 {
1727  proclist_mutable_iter iter;
1728 
1729  PRINT_LWDEBUG("LWLockUpdateVar", lock, LW_EXCLUSIVE);
1730 
1731  /*
1732  * Note that pg_atomic_exchange_u64 is a full barrier, so we're guaranteed
1733  * that the variable is updated before waking up waiters.
1734  */
1735  pg_atomic_exchange_u64(valptr, val);
1736 
1738 
1739  LWLockWaitListLock(lock);
1740 
1742 
1743  /*
1744  * See if there are any LW_WAIT_UNTIL_FREE waiters that need to be woken
1745  * up. They are always in the front of the queue.
1746  */
1747  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
1748  {
1749  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1750 
1751  if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
1752  break;
1753 
1754  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
1755  proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
1756 
1757  /* see LWLockWakeup() */
1758  Assert(waiter->lwWaiting == LW_WS_WAITING);
1759  waiter->lwWaiting = LW_WS_PENDING_WAKEUP;
1760  }
1761 
1762  /* We are done updating shared state of the lock itself. */
1763  LWLockWaitListUnlock(lock);
1764 
1765  /*
1766  * Awaken any waiters I removed from the queue.
1767  */
1768  proclist_foreach_modify(iter, &wakeup, lwWaitLink)
1769  {
1770  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1771 
1772  proclist_delete(&wakeup, iter.cur, lwWaitLink);
1773  /* check comment in LWLockWakeup() about this barrier */
1774  pg_write_barrier();
1775  waiter->lwWaiting = LW_WS_NOT_WAITING;
1776  PGSemaphoreUnlock(waiter->sem);
1777  }
1778 }
#define pg_write_barrier()
Definition: atomics.h:152
@ LW_WS_PENDING_WAKEUP
Definition: lwlock.h:31
#define GetPGProcByNumber(n)
Definition: proc.h:428
#define proclist_foreach_modify(iter, lhead, link_member)
Definition: proclist.h:206
static TimestampTz wakeup[NUM_WALRCV_WAKEUPS]
Definition: walreceiver.c:129

References Assert(), proclist_mutable_iter::cur, GetPGProcByNumber, LW_EXCLUSIVE, LW_VAL_EXCLUSIVE, LW_WAIT_UNTIL_FREE, LW_WS_NOT_WAITING, LW_WS_PENDING_WAKEUP, LW_WS_WAITING, LWLockWaitListLock(), LWLockWaitListUnlock(), PGPROC::lwWaiting, PGPROC::lwWaitMode, pg_atomic_exchange_u64(), pg_atomic_read_u32(), pg_write_barrier, PGSemaphoreUnlock(), PRINT_LWDEBUG, proclist_delete, proclist_foreach_modify, proclist_init(), proclist_push_tail, PGPROC::sem, LWLock::state, val, LWLock::waiters, and wakeup.

Referenced by WALInsertLockAcquireExclusive(), and WALInsertLockUpdateInsertingAt().

◆ LWLockWaitForVar()

bool LWLockWaitForVar ( LWLock lock,
pg_atomic_uint64 valptr,
uint64  oldval,
uint64 *  newval 
)

Definition at line 1588 of file lwlock.c.

1590 {
1591  PGPROC *proc = MyProc;
1592  int extraWaits = 0;
1593  bool result = false;
1594 #ifdef LWLOCK_STATS
1595  lwlock_stats *lwstats;
1596 
1597  lwstats = get_lwlock_stats_entry(lock);
1598 #endif
1599 
1600  PRINT_LWDEBUG("LWLockWaitForVar", lock, LW_WAIT_UNTIL_FREE);
1601 
1602  /*
1603  * Lock out cancel/die interrupts while we sleep on the lock. There is no
1604  * cleanup mechanism to remove us from the wait queue if we got
1605  * interrupted.
1606  */
1607  HOLD_INTERRUPTS();
1608 
1609  /*
1610  * Loop here to check the lock's status after each time we are signaled.
1611  */
1612  for (;;)
1613  {
1614  bool mustwait;
1615 
1616  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1617  &result);
1618 
1619  if (!mustwait)
1620  break; /* the lock was free or value didn't match */
1621 
1622  /*
1623  * Add myself to wait queue. Note that this is racy, somebody else
1624  * could wakeup before we're finished queuing. NB: We're using nearly
1625  * the same twice-in-a-row lock acquisition protocol as
1626  * LWLockAcquire(). Check its comments for details. The only
1627  * difference is that we also have to check the variable's values when
1628  * checking the state of the lock.
1629  */
1631 
1632  /*
1633  * Set RELEASE_OK flag, to make sure we get woken up as soon as the
1634  * lock is released.
1635  */
1637 
1638  /*
1639  * We're now guaranteed to be woken up if necessary. Recheck the lock
1640  * and variables state.
1641  */
1642  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1643  &result);
1644 
1645  /* Ok, no conflict after we queued ourselves. Undo queueing. */
1646  if (!mustwait)
1647  {
1648  LOG_LWDEBUG("LWLockWaitForVar", lock, "free, undoing queue");
1649 
1650  LWLockDequeueSelf(lock);
1651  break;
1652  }
1653 
1654  /*
1655  * Wait until awakened.
1656  *
1657  * It is possible that we get awakened for a reason other than being
1658  * signaled by LWLockRelease. If so, loop back and wait again. Once
1659  * we've gotten the LWLock, re-increment the sema by the number of
1660  * additional signals received.
1661  */
1662  LOG_LWDEBUG("LWLockWaitForVar", lock, "waiting");
1663 
1664 #ifdef LWLOCK_STATS
1665  lwstats->block_count++;
1666 #endif
1667 
1668  LWLockReportWaitStart(lock);
1669  if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED())
1670  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE);
1671 
1672  for (;;)
1673  {
1674  PGSemaphoreLock(proc->sem);
1675  if (proc->lwWaiting == LW_WS_NOT_WAITING)
1676  break;
1677  extraWaits++;
1678  }
1679 
1680 #ifdef LOCK_DEBUG
1681  {
1682  /* not waiting anymore */
1683  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1684 
1685  Assert(nwaiters < MAX_BACKENDS);
1686  }
1687 #endif
1688 
1689  if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED())
1690  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE);
1692 
1693  LOG_LWDEBUG("LWLockWaitForVar", lock, "awakened");
1694 
1695  /* Now loop back and check the status of the lock again. */
1696  }
1697 
1698  /*
1699  * Fix the process wait semaphore's count for any absorbed wakeups.
1700  */
1701  while (extraWaits-- > 0)
1702  PGSemaphoreUnlock(proc->sem);
1703 
1704  /*
1705  * Now okay to allow cancel/die interrupts.
1706  */
1708 
1709  return result;
1710 }
static bool LWLockConflictsWithVar(LWLock *lock, pg_atomic_uint64 *valptr, uint64 oldval, uint64 *newval, bool *result)
Definition: lwlock.c:1527

References Assert(), HOLD_INTERRUPTS, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_RELEASE_OK, LW_WAIT_UNTIL_FREE, LW_WS_NOT_WAITING, LWLockConflictsWithVar(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MyProc, newval, pg_atomic_fetch_or_u32(), pg_atomic_fetch_sub_u32(), PG_USED_FOR_ASSERTS_ONLY, PGSemaphoreLock(), PGSemaphoreUnlock(), PRINT_LWDEBUG, RESUME_INTERRUPTS, PGPROC::sem, LWLock::state, and T_NAME.

Referenced by WaitXLogInsertionsToFinish().

◆ LWLockWaitListLock()

static void LWLockWaitListLock ( LWLock lock)
static

Definition at line 859 of file lwlock.c.

860 {
861  uint32 old_state;
862 #ifdef LWLOCK_STATS
863  lwlock_stats *lwstats;
864  uint32 delays = 0;
865 
866  lwstats = get_lwlock_stats_entry(lock);
867 #endif
868 
869  while (true)
870  {
871  /* always try once to acquire lock directly */
872  old_state = pg_atomic_fetch_or_u32(&lock->state, LW_FLAG_LOCKED);
873  if (!(old_state & LW_FLAG_LOCKED))
874  break; /* got lock */
875 
876  /* and then spin without atomic operations until lock is released */
877  {
878  SpinDelayStatus delayStatus;
879 
880  init_local_spin_delay(&delayStatus);
881 
882  while (old_state & LW_FLAG_LOCKED)
883  {
884  perform_spin_delay(&delayStatus);
885  old_state = pg_atomic_read_u32(&lock->state);
886  }
887 #ifdef LWLOCK_STATS
888  delays += delayStatus.delays;
889 #endif
890  finish_spin_delay(&delayStatus);
891  }
892 
893  /*
894  * Retry. The lock might obviously already be re-acquired by the time
895  * we're attempting to get it again.
896  */
897  }
898 
899 #ifdef LWLOCK_STATS
900  lwstats->spin_delay_count += delays;
901 #endif
902 }
#define LW_FLAG_LOCKED
Definition: lwlock.c:99
void perform_spin_delay(SpinDelayStatus *status)
Definition: s_lock.c:132
void finish_spin_delay(SpinDelayStatus *status)
Definition: s_lock.c:192
#define init_local_spin_delay(status)
Definition: s_lock.h:843

References SpinDelayStatus::delays, finish_spin_delay(), init_local_spin_delay, LW_FLAG_LOCKED, perform_spin_delay(), pg_atomic_fetch_or_u32(), pg_atomic_read_u32(), and LWLock::state.

Referenced by LWLockDequeueSelf(), LWLockQueueSelf(), LWLockUpdateVar(), and LWLockWakeup().

◆ LWLockWaitListUnlock()

static void LWLockWaitListUnlock ( LWLock lock)
static

Definition at line 911 of file lwlock.c.

912 {
914 
915  old_state = pg_atomic_fetch_and_u32(&lock->state, ~LW_FLAG_LOCKED);
916 
917  Assert(old_state & LW_FLAG_LOCKED);
918 }

References Assert(), LW_FLAG_LOCKED, pg_atomic_fetch_and_u32(), PG_USED_FOR_ASSERTS_ONLY, and LWLock::state.

Referenced by LWLockDequeueSelf(), LWLockQueueSelf(), and LWLockUpdateVar().

◆ LWLockWakeup()

static void LWLockWakeup ( LWLock lock)
static

Definition at line 924 of file lwlock.c.

925 {
926  bool new_release_ok;
927  bool wokeup_somebody = false;
930 
932 
933  new_release_ok = true;
934 
935  /* lock wait list while collecting backends to wake up */
936  LWLockWaitListLock(lock);
937 
938  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
939  {
940  PGPROC *waiter = GetPGProcByNumber(iter.cur);
941 
942  if (wokeup_somebody && waiter->lwWaitMode == LW_EXCLUSIVE)
943  continue;
944 
945  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
946  proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
947 
948  if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
949  {
950  /*
951  * Prevent additional wakeups until retryer gets to run. Backends
952  * that are just waiting for the lock to become free don't retry
953  * automatically.
954  */
955  new_release_ok = false;
956 
957  /*
958  * Don't wakeup (further) exclusive locks.
959  */
960  wokeup_somebody = true;
961  }
962 
963  /*
964  * Signal that the process isn't on the wait list anymore. This allows
965  * LWLockDequeueSelf() to remove itself of the waitlist with a
966  * proclist_delete(), rather than having to check if it has been
967  * removed from the list.
968  */
969  Assert(waiter->lwWaiting == LW_WS_WAITING);
971 
972  /*
973  * Once we've woken up an exclusive lock, there's no point in waking
974  * up anybody else.
975  */
976  if (waiter->lwWaitMode == LW_EXCLUSIVE)
977  break;
978  }
979 
981 
982  /* unset required flags, and release lock, in one fell swoop */
983  {
984  uint32 old_state;
985  uint32 desired_state;
986 
987  old_state = pg_atomic_read_u32(&lock->state);
988  while (true)
989  {
990  desired_state = old_state;
991 
992  /* compute desired flags */
993 
994  if (new_release_ok)
995  desired_state |= LW_FLAG_RELEASE_OK;
996  else
997  desired_state &= ~LW_FLAG_RELEASE_OK;
998 
1000  desired_state &= ~LW_FLAG_HAS_WAITERS;
1001 
1002  desired_state &= ~LW_FLAG_LOCKED; /* release lock */
1003 
1004  if (pg_atomic_compare_exchange_u32(&lock->state, &old_state,
1005  desired_state))
1006  break;
1007  }
1008  }
1009 
1010  /* Awaken any waiters I removed from the queue. */
1011  proclist_foreach_modify(iter, &wakeup, lwWaitLink)
1012  {
1013  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1014 
1015  LOG_LWDEBUG("LWLockRelease", lock, "release waiter");
1016  proclist_delete(&wakeup, iter.cur, lwWaitLink);
1017 
1018  /*
1019  * Guarantee that lwWaiting being unset only becomes visible once the
1020  * unlink from the link has completed. Otherwise the target backend
1021  * could be woken up for other reason and enqueue for a new lock - if
1022  * that happens before the list unlink happens, the list would end up
1023  * being corrupted.
1024  *
1025  * The barrier pairs with the LWLockWaitListLock() when enqueuing for
1026  * another lock.
1027  */
1028  pg_write_barrier();
1029  waiter->lwWaiting = LW_WS_NOT_WAITING;
1030  PGSemaphoreUnlock(waiter->sem);
1031  }
1032 }

References Assert(), proclist_mutable_iter::cur, GetPGProcByNumber, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_HAS_WAITERS, LW_FLAG_LOCKED, LW_FLAG_RELEASE_OK, LW_WAIT_UNTIL_FREE, LW_WS_NOT_WAITING, LW_WS_PENDING_WAKEUP, LW_WS_WAITING, LWLockWaitListLock(), PGPROC::lwWaiting, PGPROC::lwWaitMode, pg_atomic_compare_exchange_u32(), pg_atomic_read_u32(), pg_write_barrier, PGSemaphoreUnlock(), proclist_delete, proclist_foreach_modify, proclist_init(), proclist_is_empty(), proclist_push_tail, PGPROC::sem, LWLock::state, LWLock::waiters, and wakeup.

Referenced by LWLockRelease().

◆ NumLWLocksForNamedTranches()

static int NumLWLocksForNamedTranches ( void  )
static

Definition at line 406 of file lwlock.c.

407 {
408  int numLocks = 0;
409  int i;
410 
411  for (i = 0; i < NamedLWLockTrancheRequests; i++)
412  numLocks += NamedLWLockTrancheRequestArray[i].num_lwlocks;
413 
414  return numLocks;
415 }

References i, NamedLWLockTrancheRequestArray, and NamedLWLockTrancheRequests.

Referenced by InitializeLWLocks(), and LWLockShmemSize().

◆ RequestNamedLWLockTranche()

void RequestNamedLWLockTranche ( const char *  tranche_name,
int  num_lwlocks 
)

Definition at line 670 of file lwlock.c.

671 {
672  NamedLWLockTrancheRequest *request;
673 
675  elog(FATAL, "cannot request additional LWLocks outside shmem_request_hook");
676 
677  if (NamedLWLockTrancheRequestArray == NULL)
678  {
683  * sizeof(NamedLWLockTrancheRequest));
684  }
685 
687  {
689 
692  i * sizeof(NamedLWLockTrancheRequest));
694  }
695 
697  Assert(strlen(tranche_name) + 1 <= NAMEDATALEN);
698  strlcpy(request->tranche_name, tranche_name, NAMEDATALEN);
699  request->num_lwlocks = num_lwlocks;
701 }
#define FATAL
Definition: elog.h:41
static int NamedLWLockTrancheRequestsAllocated
Definition: lwlock.c:217
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1528
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:1168
bool process_shmem_requests_in_progress
Definition: miscinit.c:1782
#define NAMEDATALEN
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45

References Assert(), elog, FATAL, i, MemoryContextAlloc(), NAMEDATALEN, NamedLWLockTrancheRequestArray, NamedLWLockTrancheRequests, NamedLWLockTrancheRequestsAllocated, NamedLWLockTrancheRequest::num_lwlocks, pg_nextpower2_32(), process_shmem_requests_in_progress, repalloc(), strlcpy(), TopMemoryContext, and NamedLWLockTrancheRequest::tranche_name.

Referenced by pgss_shmem_request().

◆ StaticAssertDecl() [1/2]

StaticAssertDecl ( lengthof(BuiltinTrancheNames = =LWTRANCHE_FIRST_USER_DEFINED,
"missing entries in BuiltinTrancheNames [] 
)

◆ StaticAssertDecl() [2/2]

StaticAssertDecl ( LW_VAL_EXCLUSIVE  ,
(uint32 MAX_BACKENDS,
"MAX_BACKENDS too big for lwlock.c  
)

Variable Documentation

◆ BuiltinTrancheNames

const char* const BuiltinTrancheNames[]
static

Definition at line 131 of file lwlock.c.

Referenced by GetLWTrancheName().

◆ held_lwlocks

◆ IndividualLWLockNames

const char* const IndividualLWLockNames[]
extern

Referenced by GetLWTrancheName().

◆ LWLockTrancheNames

const char** LWLockTrancheNames = NULL
static

Definition at line 181 of file lwlock.c.

Referenced by GetLWTrancheName(), and LWLockRegisterTranche().

◆ LWLockTrancheNamesAllocated

int LWLockTrancheNamesAllocated = 0
static

Definition at line 182 of file lwlock.c.

Referenced by GetLWTrancheName(), and LWLockRegisterTranche().

◆ MainLWLockArray

◆ NamedLWLockTrancheArray

NamedLWLockTranche* NamedLWLockTrancheArray = NULL

Definition at line 228 of file lwlock.c.

Referenced by CreateLWLocks(), and InitializeLWLocks().

◆ NamedLWLockTrancheRequestArray

NamedLWLockTrancheRequest* NamedLWLockTrancheRequestArray = NULL
static

◆ NamedLWLockTrancheRequests

int NamedLWLockTrancheRequests = 0

◆ NamedLWLockTrancheRequestsAllocated

int NamedLWLockTrancheRequestsAllocated = 0
static

Definition at line 217 of file lwlock.c.

Referenced by RequestNamedLWLockTranche().

◆ num_held_lwlocks

◆ ShmemLock

slock_t* ShmemLock
extern

Definition at line 87 of file shmem.c.

Referenced by InitShmemAllocation(), LWLockNewTrancheId(), and ShmemAllocRaw().