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lwlock.c File Reference
#include "postgres.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "pg_trace.h"
#include "postmaster/postmaster.h"
#include "replication/slot.h"
#include "storage/ipc.h"
#include "storage/predicate.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 T_NAME(lock)   (LWLockTrancheArray[(lock)->tranche])
 
#define MAX_SIMUL_LWLOCKS   200
 
#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

static void InitializeLWLocks (void)
 
static void RegisterLWLockTranches (void)
 
static void LWLockReportWaitStart (LWLock *lock)
 
static void LWLockReportWaitEnd (void)
 
static int NumLWLocksByNamedTranches (void)
 
Size LWLockShmemSize (void)
 
void CreateLWLocks (void)
 
void InitLWLockAccess (void)
 
LWLockPaddedGetNamedLWLockTranche (const char *tranche_name)
 
int LWLockNewTrancheId (void)
 
void LWLockRegisterTranche (int tranche_id, 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, uint64 *valptr, uint64 oldval, uint64 *newval, bool *result)
 
bool LWLockWaitForVar (LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval)
 
void LWLockUpdateVar (LWLock *lock, uint64 *valptr, uint64 val)
 
void LWLockRelease (LWLock *lock)
 
void LWLockReleaseClearVar (LWLock *lock, uint64 *valptr, uint64 val)
 
void LWLockReleaseAll (void)
 
bool LWLockHeldByMe (LWLock *l)
 
bool LWLockHeldByMeInMode (LWLock *l, LWLockMode mode)
 

Variables

slock_tShmemLock
 
static char ** LWLockTrancheArray = NULL
 
static int LWLockTranchesAllocated = 0
 
LWLockPaddedMainLWLockArray = NULL
 
static int num_held_lwlocks = 0
 
static LWLockHandle held_lwlocks [MAX_SIMUL_LWLOCKS]
 
NamedLWLockTrancheRequestNamedLWLockTrancheRequestArray = NULL
 
static int NamedLWLockTrancheRequestsAllocated = 0
 
int NamedLWLockTrancheRequests = 0
 
NamedLWLockTrancheNamedLWLockTrancheArray = NULL
 
static bool lock_named_request_allowed = true
 

Macro Definition Documentation

#define LOG_LWDEBUG (   a,
  b,
  c 
)    ((void)0)
#define LW_FLAG_HAS_WAITERS   ((uint32) 1 << 30)

Definition at line 99 of file lwlock.c.

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

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

Definition at line 101 of file lwlock.c.

Referenced by LWLockWaitListLock(), LWLockWaitListUnlock(), and LWLockWakeup().

#define LW_FLAG_RELEASE_OK   ((uint32) 1 << 29)
#define LW_LOCK_MASK   ((uint32) ((1 << 25)-1))

Definition at line 106 of file lwlock.c.

Referenced by LWLockAttemptLock(), and LWLockRelease().

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

Definition at line 108 of file lwlock.c.

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

Definition at line 104 of file lwlock.c.

Referenced by LWLockAttemptLock(), and LWLockRelease().

#define MAX_SIMUL_LWLOCKS   200

Definition at line 133 of file lwlock.c.

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

#define PRINT_LWDEBUG (   a,
  b,
  c 
)    ((void)0)
#define T_NAME (   lock)    (LWLockTrancheArray[(lock)->tranche])

Typedef Documentation

Function Documentation

void CreateLWLocks ( void  )

Definition at line 381 of file lwlock.c.

References InitializeLWLocks(), IsUnderPostmaster, LW_VAL_EXCLUSIVE, LWLOCK_MINIMAL_SIZE, LWLOCK_PADDED_SIZE, LWLockShmemSize(), LWTRANCHE_FIRST_USER_DEFINED, MAX_BACKENDS, RegisterLWLockTranches(), ShmemAlloc(), and StaticAssertExpr.

Referenced by CreateSharedMemoryAndSemaphores().

382 {
384  "MAX_BACKENDS too big for lwlock.c");
385 
387  sizeof(LWLock) <= LWLOCK_PADDED_SIZE,
388  "Miscalculated LWLock padding");
389 
390  if (!IsUnderPostmaster)
391  {
392  Size spaceLocks = LWLockShmemSize();
393  int *LWLockCounter;
394  char *ptr;
395 
396  /* Allocate space */
397  ptr = (char *) ShmemAlloc(spaceLocks);
398 
399  /* Leave room for dynamic allocation of tranches */
400  ptr += sizeof(int);
401 
402  /* Ensure desired alignment of LWLock array */
403  ptr += LWLOCK_PADDED_SIZE - ((uintptr_t) ptr) % LWLOCK_PADDED_SIZE;
404 
405  MainLWLockArray = (LWLockPadded *) ptr;
406 
407  /*
408  * Initialize the dynamic-allocation counter for tranches, which is
409  * stored just before the first LWLock.
410  */
411  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
412  *LWLockCounter = LWTRANCHE_FIRST_USER_DEFINED;
413 
414  /* Initialize all LWLocks */
416  }
417 
418  /* Register all LWLock tranches */
420 }
Definition: lwlock.h:32
void * ShmemAlloc(Size size)
Definition: shmem.c:157
Size LWLockShmemSize(void)
Definition: lwlock.c:349
static void RegisterLWLockTranches(void)
Definition: lwlock.c:491
#define LWLOCK_MINIMAL_SIZE
Definition: lwlock.h:74
#define MAX_BACKENDS
Definition: postmaster.h:75
bool IsUnderPostmaster
Definition: globals.c:100
unsigned int uint32
Definition: c.h:268
static void InitializeLWLocks(void)
Definition: lwlock.c:426
#define StaticAssertExpr(condition, errmessage)
Definition: c.h:759
size_t Size
Definition: c.h:356
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
#define LWLOCK_PADDED_SIZE
Definition: lwlock.h:73
LWLockPadded * MainLWLockArray
Definition: lwlock.c:125
const char* GetLWLockIdentifier ( uint32  classId,
uint16  eventId 
)

Definition at line 703 of file lwlock.c.

References Assert, LWLockTrancheArray, LWLockTranchesAllocated, NULL, and PG_WAIT_LWLOCK.

Referenced by pgstat_get_wait_event().

704 {
705  Assert(classId == PG_WAIT_LWLOCK);
706 
707  /*
708  * It is quite possible that user has registered tranche in one of the
709  * backends (e.g. by allocating lwlocks in dynamic shared memory) but not
710  * all of them, so we can't assume the tranche is registered here.
711  */
712  if (eventId >= LWLockTranchesAllocated ||
713  LWLockTrancheArray[eventId] == NULL)
714  return "extension";
715 
716  return LWLockTrancheArray[eventId];
717 }
static int LWLockTranchesAllocated
Definition: lwlock.c:115
static char ** LWLockTrancheArray
Definition: lwlock.c:114
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
#define PG_WAIT_LWLOCK
Definition: pgstat.h:737
LWLockPadded* GetNamedLWLockTranche ( const char *  tranche_name)

Definition at line 541 of file lwlock.c.

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

Referenced by pgss_shmem_startup().

542 {
543  int lock_pos;
544  int i;
545 
546  /*
547  * Obtain the position of base address of LWLock belonging to requested
548  * tranche_name in MainLWLockArray. LWLocks for named tranches are placed
549  * in MainLWLockArray after fixed locks.
550  */
551  lock_pos = NUM_FIXED_LWLOCKS;
552  for (i = 0; i < NamedLWLockTrancheRequests; i++)
553  {
554  if (strcmp(NamedLWLockTrancheRequestArray[i].tranche_name,
555  tranche_name) == 0)
556  return &MainLWLockArray[lock_pos];
557 
559  }
560 
561  if (i >= NamedLWLockTrancheRequests)
562  elog(ERROR, "requested tranche is not registered");
563 
564  /* just to keep compiler quiet */
565  return NULL;
566 }
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:129
#define ERROR
Definition: elog.h:43
int NamedLWLockTrancheRequests
Definition: lwlock.c:154
#define NULL
Definition: c.h:229
NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:152
int i
#define elog
Definition: elog.h:219
LWLockPadded * MainLWLockArray
Definition: lwlock.c:125
static void InitializeLWLocks ( void  )
static

Definition at line 426 of file lwlock.c.

References i, LWLockPadded::lock, LWLockInitialize(), LWLockNewTrancheId(), LWTRANCHE_BUFFER_MAPPING, LWTRANCHE_LOCK_MANAGER, LWTRANCHE_PREDICATE_LOCK_MANAGER, name, NamedLWLockTrancheRequests, NUM_BUFFER_PARTITIONS, NUM_FIXED_LWLOCKS, NUM_LOCK_PARTITIONS, NamedLWLockTrancheRequest::num_lwlocks, NUM_PREDICATELOCK_PARTITIONS, NumLWLocksByNamedTranches(), NamedLWLockTrancheRequest::tranche_name, NamedLWLockTranche::trancheId, and NamedLWLockTranche::trancheName.

Referenced by CreateLWLocks().

427 {
428  int numNamedLocks = NumLWLocksByNamedTranches();
429  int id;
430  int i;
431  int j;
432  LWLockPadded *lock;
433 
434  /* Initialize all individual LWLocks in main array */
435  for (id = 0, lock = MainLWLockArray; id < NUM_INDIVIDUAL_LWLOCKS; id++, lock++)
436  LWLockInitialize(&lock->lock, id);
437 
438  /* Initialize buffer mapping LWLocks in main array */
439  lock = MainLWLockArray + NUM_INDIVIDUAL_LWLOCKS;
440  for (id = 0; id < NUM_BUFFER_PARTITIONS; id++, lock++)
442 
443  /* Initialize lmgrs' LWLocks in main array */
444  lock = MainLWLockArray + NUM_INDIVIDUAL_LWLOCKS + NUM_BUFFER_PARTITIONS;
445  for (id = 0; id < NUM_LOCK_PARTITIONS; id++, lock++)
447 
448  /* Initialize predicate lmgrs' LWLocks in main array */
449  lock = MainLWLockArray + NUM_INDIVIDUAL_LWLOCKS +
450  NUM_BUFFER_PARTITIONS + NUM_LOCK_PARTITIONS;
451  for (id = 0; id < NUM_PREDICATELOCK_PARTITIONS; id++, lock++)
453 
454  /* Initialize named tranches. */
456  {
457  char *trancheNames;
458 
460  &MainLWLockArray[NUM_FIXED_LWLOCKS + numNamedLocks];
461 
462  trancheNames = (char *) NamedLWLockTrancheArray +
465 
466  for (i = 0; i < NamedLWLockTrancheRequests; i++)
467  {
468  NamedLWLockTrancheRequest *request;
469  NamedLWLockTranche *tranche;
470  char *name;
471 
472  request = &NamedLWLockTrancheRequestArray[i];
473  tranche = &NamedLWLockTrancheArray[i];
474 
475  name = trancheNames;
476  trancheNames += strlen(request->tranche_name) + 1;
477  strcpy(name, request->tranche_name);
478  tranche->trancheId = LWLockNewTrancheId();
479  tranche->trancheName = name;
480 
481  for (j = 0; j < request->num_lwlocks; j++, lock++)
482  LWLockInitialize(&lock->lock, tranche->trancheId);
483  }
484  }
485 }
int LWLockNewTrancheId(void)
Definition: lwlock.c:572
char tranche_name[NAMEDATALEN]
Definition: lwlock.c:148
NamedLWLockTranche * NamedLWLockTrancheArray
Definition: lwlock.c:156
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:129
int NamedLWLockTrancheRequests
Definition: lwlock.c:154
#define NUM_BUFFER_PARTITIONS
Definition: lwlock.h:113
char * trancheName
Definition: lwlock.h:97
void LWLockInitialize(LWLock *lock, int tranche_id)
Definition: lwlock.c:667
LWLock lock
Definition: lwlock.h:79
static int NumLWLocksByNamedTranches(void)
Definition: lwlock.c:334
const char * name
Definition: encode.c:521
NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:152
int i
LWLockPadded * MainLWLockArray
Definition: lwlock.c:125
#define NUM_LOCK_PARTITIONS
Definition: lwlock.h:117
#define NUM_PREDICATELOCK_PARTITIONS
Definition: lwlock.h:121
void InitLWLockAccess ( void  )

Definition at line 525 of file lwlock.c.

Referenced by InitProcess().

526 {
527 #ifdef LWLOCK_STATS
528  init_lwlock_stats();
529 #endif
530 }
bool LWLockAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1111 of file lwlock.c.

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

Referenced by _bt_end_vacuum(), _bt_start_vacuum(), _bt_vacuum_cycleid(), AbortBufferIO(), AbsorbFsyncRequests(), ActivateCommitTs(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), analyze_rel(), ApplyLauncherMain(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AsyncShmemInit(), AtAbort_Twophase(), AtPrepare_PredicateLocks(), attach_internal(), AutoVacLauncherMain(), AutoVacuumRequestWork(), AutoVacWorkerMain(), BackendIdGetProc(), BackendIdGetTransactionIds(), BackendPidGetProc(), BackendXidGetPid(), BecomeLockGroupLeader(), BecomeLockGroupMember(), BootStrapCLOG(), BootStrapMultiXact(), BootStrapSUBTRANS(), BufferAlloc(), CancelDBBackends(), CancelVirtualTransaction(), check_for_freed_segments(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckRecoveryConsistency(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), CleanupInvalidationState(), ClearOldPredicateLocks(), clog_redo(), commit_ts_redo(), CountDBBackends(), CountDBConnections(), CountOtherDBBackends(), CountUserBackends(), CreateCheckPoint(), CreateEndOfRecoveryRecord(), CreateInitDecodingContext(), CreatePredicateLock(), CreateRestartPoint(), DeactivateCommitTs(), DeleteChildTargetLocks(), DeleteLockTarget(), destroy_superblock(), do_autovacuum(), do_pg_start_backup(), do_pg_stop_backup(), do_start_worker(), DropAllPredicateLocksFromTable(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), dsa_pin(), dsa_release_in_place(), dsa_set_size_limit(), dsa_trim(), dsa_unpin(), dsm_attach(), dsm_create(), dsm_detach(), dsm_pin_segment(), dsm_unpin_segment(), ensure_active_superblock(), entry_reset(), Exec_ListenPreCommit(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), FlushDatabaseBuffers(), FlushRelationBuffers(), ForceTransactionIdLimitUpdate(), ForwardFsyncRequest(), FreeWorkerInfo(), GetBackgroundWorkerPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldestXmin(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionData(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetVirtualXIDsDelayingChkpt(), HaveVirtualXIDsDelayingChkpt(), InstallXLogFileSegment(), InvalidateBuffer(), KnownAssignedXidsAdd(), KnownAssignedXidsReset(), lock_twophase_recover(), LockAcquireExtended(), LockBuffer(), LockErrorCleanup(), LockGXact(), LockHasWaiters(), LockRefindAndRelease(), LockRelease(), LockReleaseAll(), LockWaiterCount(), logicalrep_worker_attach(), logicalrep_worker_detach(), logicalrep_worker_launch(), logicalrep_worker_stop(), logicalrep_worker_wakeup(), MaintainOldSnapshotTimeMapping(), MarkAsPrepared(), MarkAsPreparing(), MaybeExtendOffsetSlru(), multixact_redo(), MultiXactAdvanceNextMXact(), MultiXactGetCheckptMulti(), MultiXactIdSetOldestMember(), MultiXactIdSetOldestVisible(), MultiXactSetNextMXact(), OldSerXidAdd(), OldSerXidGetMinConflictCommitSeqNo(), OldSerXidSetActiveSerXmin(), PageIsPredicateLocked(), perform_relmap_update(), pg_backend_random(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_get_wal_senders(), pg_stat_statements_internal(), pgss_shmem_startup(), pgss_store(), PostPrepare_Locks(), PostPrepare_MultiXact(), PostPrepare_Twophase(), PreCommit_CheckForSerializationFailure(), PreCommit_Notify(), predicatelock_twophase_recover(), PredicateLockPageSplit(), PredicateLockTwoPhaseFinish(), PrefetchBuffer(), PrepareRedoAdd(), PrepareRedoRemove(), PrescanPreparedTransactions(), ProcArrayAdd(), ProcArrayApplyRecoveryInfo(), ProcArrayApplyXidAssignment(), ProcArrayGetReplicationSlotXmin(), ProcArrayGroupClearXid(), ProcArrayInstallImportedXmin(), ProcArrayInstallRestoredXmin(), ProcArrayRemove(), ProcArraySetReplicationSlotXmin(), process_syncing_tables_for_apply(), ProcessTwoPhaseBuffer(), ProcKill(), ProcSleep(), ReadBuffer_common(), ReadMultiXactCounts(), ReadNewTransactionId(), ReadNextMultiXactId(), ReadRecord(), RecordKnownAssignedTransactionIds(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePreInvalidate(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), RemoveGXact(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquire(), ReplicationSlotCreate(), ReplicationSlotDropPtr(), ReplicationSlotRelease(), ReplicationSlotsComputeLogicalRestartLSN(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotsCountDBSlots(), ReplicationSlotsDropDBSlots(), replorigin_advance(), replorigin_drop(), replorigin_get_progress(), replorigin_session_advance(), replorigin_session_get_progress(), replorigin_session_reset(), replorigin_session_setup(), RestoreScratchTarget(), SaveSlotToPath(), SetCommitTsLimit(), SetMultiXactIdLimit(), SetOffsetVacuumLimit(), SetTransactionIdLimit(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SIInsertDataEntries(), SimpleLruFlush(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), StandbyRecoverPreparedTransactions(), StartBufferIO(), StartupCLOG(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SyncOneBuffer(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepInitConfig(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TransactionIdGetCommitTsData(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdLimitedForOldSnapshots(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), txid_status(), UpdateMinRecoveryPoint(), vacuum_rel(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_sync_status_change(), WaitForReplicationWorkerAttach(), WaitIO(), WALInsertLockAcquire(), WALInsertLockAcquireExclusive(), write_relcache_init_file(), xact_redo_abort(), xact_redo_commit(), XidCacheRemoveRunningXids(), xlog_redo(), and XLogBackgroundFlush().

1112 {
1113  PGPROC *proc = MyProc;
1114  bool result = true;
1115  int extraWaits = 0;
1116 #ifdef LWLOCK_STATS
1117  lwlock_stats *lwstats;
1118 
1119  lwstats = get_lwlock_stats_entry(lock);
1120 #endif
1121 
1122  AssertArg(mode == LW_SHARED || mode == LW_EXCLUSIVE);
1123 
1124  PRINT_LWDEBUG("LWLockAcquire", lock, mode);
1125 
1126 #ifdef LWLOCK_STATS
1127  /* Count lock acquisition attempts */
1128  if (mode == LW_EXCLUSIVE)
1129  lwstats->ex_acquire_count++;
1130  else
1131  lwstats->sh_acquire_count++;
1132 #endif /* LWLOCK_STATS */
1133 
1134  /*
1135  * We can't wait if we haven't got a PGPROC. This should only occur
1136  * during bootstrap or shared memory initialization. Put an Assert here
1137  * to catch unsafe coding practices.
1138  */
1139  Assert(!(proc == NULL && IsUnderPostmaster));
1140 
1141  /* Ensure we will have room to remember the lock */
1143  elog(ERROR, "too many LWLocks taken");
1144 
1145  /*
1146  * Lock out cancel/die interrupts until we exit the code section protected
1147  * by the LWLock. This ensures that interrupts will not interfere with
1148  * manipulations of data structures in shared memory.
1149  */
1150  HOLD_INTERRUPTS();
1151 
1152  /*
1153  * Loop here to try to acquire lock after each time we are signaled by
1154  * LWLockRelease.
1155  *
1156  * NOTE: it might seem better to have LWLockRelease actually grant us the
1157  * lock, rather than retrying and possibly having to go back to sleep. But
1158  * in practice that is no good because it means a process swap for every
1159  * lock acquisition when two or more processes are contending for the same
1160  * lock. Since LWLocks are normally used to protect not-very-long
1161  * sections of computation, a process needs to be able to acquire and
1162  * release the same lock many times during a single CPU time slice, even
1163  * in the presence of contention. The efficiency of being able to do that
1164  * outweighs the inefficiency of sometimes wasting a process dispatch
1165  * cycle because the lock is not free when a released waiter finally gets
1166  * to run. See pgsql-hackers archives for 29-Dec-01.
1167  */
1168  for (;;)
1169  {
1170  bool mustwait;
1171 
1172  /*
1173  * Try to grab the lock the first time, we're not in the waitqueue
1174  * yet/anymore.
1175  */
1176  mustwait = LWLockAttemptLock(lock, mode);
1177 
1178  if (!mustwait)
1179  {
1180  LOG_LWDEBUG("LWLockAcquire", lock, "immediately acquired lock");
1181  break; /* got the lock */
1182  }
1183 
1184  /*
1185  * Ok, at this point we couldn't grab the lock on the first try. We
1186  * cannot simply queue ourselves to the end of the list and wait to be
1187  * woken up because by now the lock could long have been released.
1188  * Instead add us to the queue and try to grab the lock again. If we
1189  * succeed we need to revert the queuing and be happy, otherwise we
1190  * recheck the lock. If we still couldn't grab it, we know that the
1191  * other locker will see our queue entries when releasing since they
1192  * existed before we checked for the lock.
1193  */
1194 
1195  /* add to the queue */
1196  LWLockQueueSelf(lock, mode);
1197 
1198  /* we're now guaranteed to be woken up if necessary */
1199  mustwait = LWLockAttemptLock(lock, mode);
1200 
1201  /* ok, grabbed the lock the second time round, need to undo queueing */
1202  if (!mustwait)
1203  {
1204  LOG_LWDEBUG("LWLockAcquire", lock, "acquired, undoing queue");
1205 
1206  LWLockDequeueSelf(lock);
1207  break;
1208  }
1209 
1210  /*
1211  * Wait until awakened.
1212  *
1213  * Since we share the process wait semaphore with the regular lock
1214  * manager and ProcWaitForSignal, and we may need to acquire an LWLock
1215  * while one of those is pending, it is possible that we get awakened
1216  * for a reason other than being signaled by LWLockRelease. If so,
1217  * loop back and wait again. Once we've gotten the LWLock,
1218  * re-increment the sema by the number of additional signals received,
1219  * so that the lock manager or signal manager will see the received
1220  * signal when it next waits.
1221  */
1222  LOG_LWDEBUG("LWLockAcquire", lock, "waiting");
1223 
1224 #ifdef LWLOCK_STATS
1225  lwstats->block_count++;
1226 #endif
1227 
1228  LWLockReportWaitStart(lock);
1229  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1230 
1231  for (;;)
1232  {
1233  PGSemaphoreLock(proc->sem);
1234  if (!proc->lwWaiting)
1235  break;
1236  extraWaits++;
1237  }
1238 
1239  /* Retrying, allow LWLockRelease to release waiters again. */
1241 
1242 #ifdef LOCK_DEBUG
1243  {
1244  /* not waiting anymore */
1245  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1246 
1247  Assert(nwaiters < MAX_BACKENDS);
1248  }
1249 #endif
1250 
1251  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1253 
1254  LOG_LWDEBUG("LWLockAcquire", lock, "awakened");
1255 
1256  /* Now loop back and try to acquire lock again. */
1257  result = false;
1258  }
1259 
1260  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode);
1261 
1262  /* Add lock to list of locks held by this backend */
1265 
1266  /*
1267  * Fix the process wait semaphore's count for any absorbed wakeups.
1268  */
1269  while (extraWaits-- > 0)
1270  PGSemaphoreUnlock(proc->sem);
1271 
1272  return result;
1273 }
#define T_NAME(lock)
Definition: lwlock.c:117
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:354
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:729
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
PGPROC * MyProc
Definition: proc.c:67
bool lwWaiting
Definition: proc.h:126
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:133
return result
Definition: formatting.c:1618
pg_atomic_uint32 state
Definition: lwlock.h:35
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:143
#define ERROR
Definition: elog.h:43
#define MAX_BACKENDS
Definition: postmaster.h:75
LWLockMode mode
Definition: lwlock.c:139
bool IsUnderPostmaster
Definition: globals.c:100
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:694
unsigned int uint32
Definition: c.h:268
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1016
#define AssertArg(condition)
Definition: c.h:677
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:685
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:972
static int num_held_lwlocks
Definition: lwlock.c:142
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
LWLock * lock
Definition: lwlock.c:138
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:227
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:303
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:114
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:383
#define elog
Definition: elog.h:219
PGSemaphore sem
Definition: proc.h:100
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:990
Definition: proc.h:94
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
bool LWLockAcquireOrWait ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1338 of file lwlock.c.

References Assert, elog, ERROR, HOLD_INTERRUPTS, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_SHARED, LW_WAIT_UNTIL_FREE, LWLockAttemptLock(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MAX_SIMUL_LWLOCKS, LWLockHandle::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().

1339 {
1340  PGPROC *proc = MyProc;
1341  bool mustwait;
1342  int extraWaits = 0;
1343 #ifdef LWLOCK_STATS
1344  lwlock_stats *lwstats;
1345 
1346  lwstats = get_lwlock_stats_entry(lock);
1347 #endif
1348 
1349  Assert(mode == LW_SHARED || mode == LW_EXCLUSIVE);
1350 
1351  PRINT_LWDEBUG("LWLockAcquireOrWait", lock, mode);
1352 
1353  /* Ensure we will have room to remember the lock */
1355  elog(ERROR, "too many LWLocks taken");
1356 
1357  /*
1358  * Lock out cancel/die interrupts until we exit the code section protected
1359  * by the LWLock. This ensures that interrupts will not interfere with
1360  * manipulations of data structures in shared memory.
1361  */
1362  HOLD_INTERRUPTS();
1363 
1364  /*
1365  * NB: We're using nearly the same twice-in-a-row lock acquisition
1366  * protocol as LWLockAcquire(). Check its comments for details.
1367  */
1368  mustwait = LWLockAttemptLock(lock, mode);
1369 
1370  if (mustwait)
1371  {
1373 
1374  mustwait = LWLockAttemptLock(lock, mode);
1375 
1376  if (mustwait)
1377  {
1378  /*
1379  * Wait until awakened. Like in LWLockAcquire, be prepared for
1380  * bogus wakeups, because we share the semaphore with
1381  * ProcWaitForSignal.
1382  */
1383  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "waiting");
1384 
1385 #ifdef LWLOCK_STATS
1386  lwstats->block_count++;
1387 #endif
1388 
1389  LWLockReportWaitStart(lock);
1390  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1391 
1392  for (;;)
1393  {
1394  PGSemaphoreLock(proc->sem);
1395  if (!proc->lwWaiting)
1396  break;
1397  extraWaits++;
1398  }
1399 
1400 #ifdef LOCK_DEBUG
1401  {
1402  /* not waiting anymore */
1403  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1404 
1405  Assert(nwaiters < MAX_BACKENDS);
1406  }
1407 #endif
1408  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1410 
1411  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "awakened");
1412  }
1413  else
1414  {
1415  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "acquired, undoing queue");
1416 
1417  /*
1418  * Got lock in the second attempt, undo queueing. We need to treat
1419  * this as having successfully acquired the lock, otherwise we'd
1420  * not necessarily wake up people we've prevented from acquiring
1421  * the lock.
1422  */
1423  LWLockDequeueSelf(lock);
1424  }
1425  }
1426 
1427  /*
1428  * Fix the process wait semaphore's count for any absorbed wakeups.
1429  */
1430  while (extraWaits-- > 0)
1431  PGSemaphoreUnlock(proc->sem);
1432 
1433  if (mustwait)
1434  {
1435  /* Failed to get lock, so release interrupt holdoff */
1437  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "failed");
1438  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode);
1439  }
1440  else
1441  {
1442  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "succeeded");
1443  /* Add lock to list of locks held by this backend */
1446  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode);
1447  }
1448 
1449  return !mustwait;
1450 }
#define T_NAME(lock)
Definition: lwlock.c:117
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:354
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:729
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
PGPROC * MyProc
Definition: proc.c:67
bool lwWaiting
Definition: proc.h:126
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:133
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:116
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:143
#define ERROR
Definition: elog.h:43
#define MAX_BACKENDS
Definition: postmaster.h:75
LWLockMode mode
Definition: lwlock.c:139
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:694
unsigned int uint32
Definition: c.h:268
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1016
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:685
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:972
static int num_held_lwlocks
Definition: lwlock.c:142
#define Assert(condition)
Definition: c.h:675
LWLock * lock
Definition: lwlock.c:138
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:227
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:303
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:114
#define elog
Definition: elog.h:219
PGSemaphore sem
Definition: proc.h:100
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:990
Definition: proc.h:94
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
static bool LWLockAttemptLock ( LWLock lock,
LWLockMode  mode 
)
static

Definition at line 729 of file lwlock.c.

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

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

730 {
731  uint32 old_state;
732 
733  AssertArg(mode == LW_EXCLUSIVE || mode == LW_SHARED);
734 
735  /*
736  * Read once outside the loop, later iterations will get the newer value
737  * via compare & exchange.
738  */
739  old_state = pg_atomic_read_u32(&lock->state);
740 
741  /* loop until we've determined whether we could acquire the lock or not */
742  while (true)
743  {
744  uint32 desired_state;
745  bool lock_free;
746 
747  desired_state = old_state;
748 
749  if (mode == LW_EXCLUSIVE)
750  {
751  lock_free = (old_state & LW_LOCK_MASK) == 0;
752  if (lock_free)
753  desired_state += LW_VAL_EXCLUSIVE;
754  }
755  else
756  {
757  lock_free = (old_state & LW_VAL_EXCLUSIVE) == 0;
758  if (lock_free)
759  desired_state += LW_VAL_SHARED;
760  }
761 
762  /*
763  * Attempt to swap in the state we are expecting. If we didn't see
764  * lock to be free, that's just the old value. If we saw it as free,
765  * we'll attempt to mark it acquired. The reason that we always swap
766  * in the value is that this doubles as a memory barrier. We could try
767  * to be smarter and only swap in values if we saw the lock as free,
768  * but benchmark haven't shown it as beneficial so far.
769  *
770  * Retry if the value changed since we last looked at it.
771  */
773  &old_state, desired_state))
774  {
775  if (lock_free)
776  {
777  /* Great! Got the lock. */
778 #ifdef LOCK_DEBUG
779  if (mode == LW_EXCLUSIVE)
780  lock->owner = MyProc;
781 #endif
782  return false;
783  }
784  else
785  return true; /* somebody else has the lock */
786  }
787  }
788  pg_unreachable();
789 }
#define pg_unreachable()
Definition: c.h:946
static bool pg_atomic_compare_exchange_u32(volatile pg_atomic_uint32 *ptr, uint32 *expected, uint32 newval)
Definition: atomics.h:322
PGPROC * MyProc
Definition: proc.c:67
pg_atomic_uint32 state
Definition: lwlock.h:35
#define LW_LOCK_MASK
Definition: lwlock.c:106
#define LW_VAL_SHARED
Definition: lwlock.c:104
unsigned int uint32
Definition: c.h:268
#define AssertArg(condition)
Definition: c.h:677
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:252
bool LWLockConditionalAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1283 of file lwlock.c.

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

Referenced by BufferAlloc(), ConditionalLockBuffer(), ProcArrayEndTransaction(), SimpleLruWaitIO(), ss_report_location(), and XLogNeedsFlush().

1284 {
1285  bool mustwait;
1286 
1287  AssertArg(mode == LW_SHARED || mode == LW_EXCLUSIVE);
1288 
1289  PRINT_LWDEBUG("LWLockConditionalAcquire", lock, mode);
1290 
1291  /* Ensure we will have room to remember the lock */
1293  elog(ERROR, "too many LWLocks taken");
1294 
1295  /*
1296  * Lock out cancel/die interrupts until we exit the code section protected
1297  * by the LWLock. This ensures that interrupts will not interfere with
1298  * manipulations of data structures in shared memory.
1299  */
1300  HOLD_INTERRUPTS();
1301 
1302  /* Check for the lock */
1303  mustwait = LWLockAttemptLock(lock, mode);
1304 
1305  if (mustwait)
1306  {
1307  /* Failed to get lock, so release interrupt holdoff */
1309 
1310  LOG_LWDEBUG("LWLockConditionalAcquire", lock, "failed");
1311  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode);
1312  }
1313  else
1314  {
1315  /* Add lock to list of locks held by this backend */
1318  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode);
1319  }
1320  return !mustwait;
1321 }
#define T_NAME(lock)
Definition: lwlock.c:117
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:729
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:133
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:116
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:143
#define ERROR
Definition: elog.h:43
LWLockMode mode
Definition: lwlock.c:139
#define AssertArg(condition)
Definition: c.h:677
static int num_held_lwlocks
Definition: lwlock.c:142
LWLock * lock
Definition: lwlock.c:138
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:227
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:114
#define elog
Definition: elog.h:219
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
static bool LWLockConflictsWithVar ( LWLock lock,
uint64 *  valptr,
uint64  oldval,
uint64 *  newval,
bool result 
)
static

Definition at line 1462 of file lwlock.c.

References LW_VAL_EXCLUSIVE, LWLockWaitListLock(), LWLockWaitListUnlock(), pg_atomic_read_u32(), LWLock::state, and value.

Referenced by LWLockWaitForVar().

1465 {
1466  bool mustwait;
1467  uint64 value;
1468 
1469  /*
1470  * Test first to see if it the slot is free right now.
1471  *
1472  * XXX: the caller uses a spinlock before this, so we don't need a memory
1473  * barrier here as far as the current usage is concerned. But that might
1474  * not be safe in general.
1475  */
1476  mustwait = (pg_atomic_read_u32(&lock->state) & LW_VAL_EXCLUSIVE) != 0;
1477 
1478  if (!mustwait)
1479  {
1480  *result = true;
1481  return false;
1482  }
1483 
1484  *result = false;
1485 
1486  /*
1487  * Read value using the lwlock's wait list lock, as we can't generally
1488  * rely on atomic 64 bit reads/stores. TODO: On platforms with a way to
1489  * do atomic 64 bit reads/writes the spinlock should be optimized away.
1490  */
1491  LWLockWaitListLock(lock);
1492  value = *valptr;
1493  LWLockWaitListUnlock(lock);
1494 
1495  if (value != oldval)
1496  {
1497  mustwait = false;
1498  *newval = value;
1499  }
1500  else
1501  {
1502  mustwait = true;
1503  }
1504 
1505  return mustwait;
1506 }
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:852
return result
Definition: formatting.c:1618
pg_atomic_uint32 state
Definition: lwlock.h:35
#define newval
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:800
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
static struct @121 value
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:252
static void LWLockDequeueSelf ( LWLock lock)
static

Definition at line 1016 of file lwlock.c.

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

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

1017 {
1018  bool found = false;
1019  proclist_mutable_iter iter;
1020 
1021 #ifdef LWLOCK_STATS
1022  lwlock_stats *lwstats;
1023 
1024  lwstats = get_lwlock_stats_entry(lock);
1025 
1026  lwstats->dequeue_self_count++;
1027 #endif
1028 
1029  LWLockWaitListLock(lock);
1030 
1031  /*
1032  * Can't just remove ourselves from the list, but we need to iterate over
1033  * all entries as somebody else could have dequeued us.
1034  */
1035  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
1036  {
1037  if (iter.cur == MyProc->pgprocno)
1038  {
1039  found = true;
1040  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
1041  break;
1042  }
1043  }
1044 
1045  if (proclist_is_empty(&lock->waiters) &&
1046  (pg_atomic_read_u32(&lock->state) & LW_FLAG_HAS_WAITERS) != 0)
1047  {
1049  }
1050 
1051  /* XXX: combine with fetch_and above? */
1052  LWLockWaitListUnlock(lock);
1053 
1054  /* clear waiting state again, nice for debugging */
1055  if (found)
1056  MyProc->lwWaiting = false;
1057  else
1058  {
1059  int extraWaits = 0;
1060 
1061  /*
1062  * Somebody else dequeued us and has or will wake us up. Deal with the
1063  * superfluous absorption of a wakeup.
1064  */
1065 
1066  /*
1067  * Reset releaseOk if somebody woke us before we removed ourselves -
1068  * they'll have set it to false.
1069  */
1071 
1072  /*
1073  * Now wait for the scheduled wakeup, otherwise our ->lwWaiting would
1074  * get reset at some inconvenient point later. Most of the time this
1075  * will immediately return.
1076  */
1077  for (;;)
1078  {
1080  if (!MyProc->lwWaiting)
1081  break;
1082  extraWaits++;
1083  }
1084 
1085  /*
1086  * Fix the process wait semaphore's count for any absorbed wakeups.
1087  */
1088  while (extraWaits-- > 0)
1090  }
1091 
1092 #ifdef LOCK_DEBUG
1093  {
1094  /* not waiting anymore */
1095  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1096 
1097  Assert(nwaiters < MAX_BACKENDS);
1098  }
1099 #endif
1100 }
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:354
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
#define LW_FLAG_HAS_WAITERS
Definition: lwlock.c:99
PGPROC * MyProc
Definition: proc.c:67
proclist_head waiters
Definition: lwlock.h:36
bool lwWaiting
Definition: proc.h:126
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:852
#define proclist_foreach_modify(iter, lhead, link_member)
Definition: proclist.h:195
pg_atomic_uint32 state
Definition: lwlock.h:35
#define proclist_delete(list, procno, link_member)
Definition: proclist.h:176
#define MAX_BACKENDS
Definition: postmaster.h:75
static uint32 pg_atomic_fetch_and_u32(volatile pg_atomic_uint32 *ptr, uint32 and_)
Definition: atomics.h:369
unsigned int uint32
Definition: c.h:268
#define Assert(condition)
Definition: c.h:675
static bool proclist_is_empty(proclist_head *list)
Definition: proclist.h:38
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:303
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:800
int pgprocno
Definition: proc.h:109
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:383
PGSemaphore sem
Definition: proc.h:100
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:990
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:252
bool LWLockHeldByMeInMode ( LWLock l,
LWLockMode  mode 
)

Definition at line 1849 of file lwlock.c.

References i, and num_held_lwlocks.

Referenced by IsBufferCleanupOK(), logicalrep_worker_cleanup(), and MarkBufferDirty().

1850 {
1851  int i;
1852 
1853  for (i = 0; i < num_held_lwlocks; i++)
1854  {
1855  if (held_lwlocks[i].lock == l && held_lwlocks[i].mode == mode)
1856  return true;
1857  }
1858  return false;
1859 }
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:143
static int num_held_lwlocks
Definition: lwlock.c:142
int i
void LWLockInitialize ( LWLock lock,
int  tranche_id 
)

Definition at line 667 of file lwlock.c.

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

Referenced by create_internal(), InitBufferPool(), InitializeLWLocks(), InitProcGlobal(), ReplicationOriginShmemInit(), ReplicationSlotsShmemInit(), SimpleLruInit(), tbm_prepare_shared_iterate(), and XLOGShmemInit().

668 {
670 #ifdef LOCK_DEBUG
671  pg_atomic_init_u32(&lock->nwaiters, 0);
672 #endif
673  lock->tranche = tranche_id;
674  proclist_init(&lock->waiters);
675 }
proclist_head waiters
Definition: lwlock.h:36
pg_atomic_uint32 state
Definition: lwlock.h:35
uint16 tranche
Definition: lwlock.h:34
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
static void proclist_init(proclist_head *list)
Definition: proclist.h:29
static void pg_atomic_init_u32(volatile pg_atomic_uint32 *ptr, uint32 val)
Definition: atomics.h:234
int LWLockNewTrancheId ( void  )

Definition at line 572 of file lwlock.c.

References result, ShmemLock, SpinLockAcquire, and SpinLockRelease.

Referenced by InitializeLWLocks().

573 {
574  int result;
575  int *LWLockCounter;
576 
577  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
579  result = (*LWLockCounter)++;
581 
582  return result;
583 }
return result
Definition: formatting.c:1618
#define SpinLockAcquire(lock)
Definition: spin.h:62
#define SpinLockRelease(lock)
Definition: spin.h:64
slock_t * ShmemLock
Definition: shmem.c:84
LWLockPadded * MainLWLockArray
Definition: lwlock.c:125
static void LWLockQueueSelf ( LWLock lock,
LWLockMode  mode 
)
static

Definition at line 972 of file lwlock.c.

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

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

973 {
974  /*
975  * If we don't have a PGPROC structure, there's no way to wait. This
976  * should never occur, since MyProc should only be null during shared
977  * memory initialization.
978  */
979  if (MyProc == NULL)
980  elog(PANIC, "cannot wait without a PGPROC structure");
981 
982  if (MyProc->lwWaiting)
983  elog(PANIC, "queueing for lock while waiting on another one");
984 
985  LWLockWaitListLock(lock);
986 
987  /* setting the flag is protected by the spinlock */
989 
990  MyProc->lwWaiting = true;
991  MyProc->lwWaitMode = mode;
992 
993  /* LW_WAIT_UNTIL_FREE waiters are always at the front of the queue */
994  if (mode == LW_WAIT_UNTIL_FREE)
995  proclist_push_head(&lock->waiters, MyProc->pgprocno, lwWaitLink);
996  else
997  proclist_push_tail(&lock->waiters, MyProc->pgprocno, lwWaitLink);
998 
999  /* Can release the mutex now */
1000  LWLockWaitListUnlock(lock);
1001 
1002 #ifdef LOCK_DEBUG
1003  pg_atomic_fetch_add_u32(&lock->nwaiters, 1);
1004 #endif
1005 
1006 }
#define LW_FLAG_HAS_WAITERS
Definition: lwlock.c:99
PGPROC * MyProc
Definition: proc.c:67
proclist_head waiters
Definition: lwlock.h:36
bool lwWaiting
Definition: proc.h:126
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:852
uint8 lwWaitMode
Definition: proc.h:127
pg_atomic_uint32 state
Definition: lwlock.h:35
#define PANIC
Definition: elog.h:53
#define proclist_push_head(list, procno, link_member)
Definition: proclist.h:178
static uint32 pg_atomic_fetch_add_u32(volatile pg_atomic_uint32 *ptr, int32 add_)
Definition: atomics.h:339
#define NULL
Definition: c.h:229
#define proclist_push_tail(list, procno, link_member)
Definition: proclist.h:180
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:800
int pgprocno
Definition: proc.h:109
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:383
#define elog
Definition: elog.h:219
void LWLockRegisterTranche ( int  tranche_id,
char *  tranche_name 
)

Definition at line 592 of file lwlock.c.

References Assert, i, LWLockTrancheArray, LWLockTranchesAllocated, NULL, and repalloc().

Referenced by CreateSharedProcArray(), InitBufferPool(), RegisterLWLockTranches(), ReplicationOriginShmemInit(), ReplicationSlotsShmemInit(), SimpleLruInit(), and XLOGShmemInit().

593 {
595 
596  if (tranche_id >= LWLockTranchesAllocated)
597  {
599  int j = LWLockTranchesAllocated;
600 
601  while (i <= tranche_id)
602  i *= 2;
603 
604  LWLockTrancheArray = (char **)
605  repalloc(LWLockTrancheArray, i * sizeof(char *));
607  while (j < LWLockTranchesAllocated)
608  LWLockTrancheArray[j++] = NULL;
609  }
610 
611  LWLockTrancheArray[tranche_id] = tranche_name;
612 }
static int LWLockTranchesAllocated
Definition: lwlock.c:115
static char ** LWLockTrancheArray
Definition: lwlock.c:114
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:963
int i
void LWLockRelease ( LWLock lock)

Definition at line 1715 of file lwlock.c.

References Assert, elog, ERROR, 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, num_held_lwlocks, pg_atomic_sub_fetch_u32(), PRINT_LWDEBUG, RESUME_INTERRUPTS, and T_NAME.

Referenced by _bt_end_vacuum(), _bt_start_vacuum(), _bt_vacuum_cycleid(), AbsorbFsyncRequests(), ActivateCommitTs(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), analyze_rel(), ApplyLauncherMain(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AsyncShmemInit(), AtAbort_Twophase(), AtPrepare_PredicateLocks(), attach_internal(), AutoVacLauncherMain(), AutoVacuumRequestWork(), AutoVacWorkerMain(), BackendIdGetProc(), BackendIdGetTransactionIds(), BackendPidGetProc(), BackendXidGetPid(), BecomeLockGroupLeader(), BecomeLockGroupMember(), BootStrapCLOG(), BootStrapMultiXact(), BootStrapSUBTRANS(), BufferAlloc(), CancelDBBackends(), CancelVirtualTransaction(), check_for_freed_segments(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckRecoveryConsistency(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), CleanupInvalidationState(), ClearOldPredicateLocks(), clog_redo(), commit_ts_redo(), CountDBBackends(), CountDBConnections(), CountOtherDBBackends(), CountUserBackends(), CreateCheckPoint(), CreateEndOfRecoveryRecord(), CreateInitDecodingContext(), CreatePredicateLock(), CreateRestartPoint(), DeactivateCommitTs(), DeleteChildTargetLocks(), DeleteLockTarget(), destroy_superblock(), do_autovacuum(), do_pg_start_backup(), do_pg_stop_backup(), do_start_worker(), DropAllPredicateLocksFromTable(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), dsa_pin(), dsa_release_in_place(), dsa_set_size_limit(), dsa_trim(), dsa_unpin(), dsm_attach(), dsm_create(), dsm_detach(), dsm_pin_segment(), dsm_unpin_segment(), ensure_active_superblock(), entry_reset(), Exec_ListenPreCommit(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), find_multixact_start(), FlushDatabaseBuffers(), FlushRelationBuffers(), ForceTransactionIdLimitUpdate(), ForwardFsyncRequest(), FreeWorkerInfo(), GetBackgroundWorkerPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldestXmin(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetVirtualXIDsDelayingChkpt(), HaveVirtualXIDsDelayingChkpt(), InstallXLogFileSegment(), InvalidateBuffer(), KnownAssignedXidsAdd(), KnownAssignedXidsReset(), lock_twophase_recover(), LockAcquireExtended(), LockBuffer(), LockErrorCleanup(), LockGXact(), LockHasWaiters(), LockRefindAndRelease(), LockRelease(), LockReleaseAll(), LockWaiterCount(), logicalrep_worker_attach(), logicalrep_worker_detach(), logicalrep_worker_launch(), logicalrep_worker_stop(), logicalrep_worker_wakeup(), LogStandbySnapshot(), LWLockReleaseAll(), LWLockReleaseClearVar(), MaintainOldSnapshotTimeMapping(), MarkAsPrepared(), MarkAsPreparing(), MaybeExtendOffsetSlru(), multixact_redo(), MultiXactAdvanceNextMXact(), MultiXactGetCheckptMulti(), MultiXactIdSetOldestMember(), MultiXactIdSetOldestVisible(), MultiXactSetNextMXact(), OldSerXidAdd(), OldSerXidGetMinConflictCommitSeqNo(), OldSerXidSetActiveSerXmin(), OnConflict_CheckForSerializationFailure(), PageIsPredicateLocked(), perform_relmap_update(), pg_backend_random(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_get_wal_senders(), pg_stat_statements_internal(), pgss_shmem_startup(), pgss_store(), PostPrepare_Locks(), PostPrepare_MultiXact(), PostPrepare_Twophase(), PreCommit_CheckForSerializationFailure(), PreCommit_Notify(), predicatelock_twophase_recover(), PredicateLockPageSplit(), PredicateLockTwoPhaseFinish(), PrefetchBuffer(), PrepareRedoAdd(), PrepareRedoRemove(), PrescanPreparedTransactions(), ProcArrayAdd(), ProcArrayApplyRecoveryInfo(), ProcArrayApplyXidAssignment(), ProcArrayEndTransaction(), ProcArrayGetReplicationSlotXmin(), ProcArrayGroupClearXid(), ProcArrayInstallImportedXmin(), ProcArrayInstallRestoredXmin(), ProcArrayRemove(), ProcArraySetReplicationSlotXmin(), process_syncing_tables_for_apply(), ProcessTwoPhaseBuffer(), ProcKill(), ProcSleep(), ReadMultiXactCounts(), ReadNewTransactionId(), ReadNextMultiXactId(), ReadRecord(), RecordKnownAssignedTransactionIds(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePostInvalidate(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), RemoveGXact(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquire(), ReplicationSlotCreate(), ReplicationSlotDropPtr(), ReplicationSlotRelease(), ReplicationSlotsComputeLogicalRestartLSN(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotsCountDBSlots(), ReplicationSlotsDropDBSlots(), replorigin_advance(), replorigin_drop(), replorigin_get_progress(), replorigin_session_advance(), replorigin_session_get_progress(), replorigin_session_reset(), replorigin_session_setup(), RestoreScratchTarget(), SaveSlotToPath(), SetCommitTsLimit(), SetMultiXactIdLimit(), SetOffsetVacuumLimit(), SetTransactionIdLimit(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SIInsertDataEntries(), SimpleLruFlush(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), ss_report_location(), StandbyRecoverPreparedTransactions(), StartBufferIO(), StartupCLOG(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), SubTransGetParent(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SyncOneBuffer(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepInitConfig(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateBufferIO(), TransactionIdGetCommitTsData(), TransactionIdGetStatus(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdLimitedForOldSnapshots(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), txid_status(), UpdateMinRecoveryPoint(), vacuum_rel(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_sync_status_change(), WaitForReplicationWorkerAttach(), WaitIO(), WaitOnLock(), write_relcache_init_file(), xact_redo_abort(), xact_redo_commit(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), XLogFlush(), and XLogNeedsFlush().

1716 {
1717  LWLockMode mode;
1718  uint32 oldstate;
1719  bool check_waiters;
1720  int i;
1721 
1722  /*
1723  * Remove lock from list of locks held. Usually, but not always, it will
1724  * be the latest-acquired lock; so search array backwards.
1725  */
1726  for (i = num_held_lwlocks; --i >= 0;)
1727  if (lock == held_lwlocks[i].lock)
1728  break;
1729 
1730  if (i < 0)
1731  elog(ERROR, "lock %s is not held", T_NAME(lock));
1732 
1733  mode = held_lwlocks[i].mode;
1734 
1735  num_held_lwlocks--;
1736  for (; i < num_held_lwlocks; i++)
1737  held_lwlocks[i] = held_lwlocks[i + 1];
1738 
1739  PRINT_LWDEBUG("LWLockRelease", lock, mode);
1740 
1741  /*
1742  * Release my hold on lock, after that it can immediately be acquired by
1743  * others, even if we still have to wakeup other waiters.
1744  */
1745  if (mode == LW_EXCLUSIVE)
1746  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_EXCLUSIVE);
1747  else
1748  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_SHARED);
1749 
1750  /* nobody else can have that kind of lock */
1751  Assert(!(oldstate & LW_VAL_EXCLUSIVE));
1752 
1753 
1754  /*
1755  * We're still waiting for backends to get scheduled, don't wake them up
1756  * again.
1757  */
1758  if ((oldstate & (LW_FLAG_HAS_WAITERS | LW_FLAG_RELEASE_OK)) ==
1760  (oldstate & LW_LOCK_MASK) == 0)
1761  check_waiters = true;
1762  else
1763  check_waiters = false;
1764 
1765  /*
1766  * As waking up waiters requires the spinlock to be acquired, only do so
1767  * if necessary.
1768  */
1769  if (check_waiters)
1770  {
1771  /* XXX: remove before commit? */
1772  LOG_LWDEBUG("LWLockRelease", lock, "releasing waiters");
1773  LWLockWakeup(lock);
1774  }
1775 
1776  TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
1777 
1778  /*
1779  * Now okay to allow cancel/die interrupts.
1780  */
1782 }
#define T_NAME(lock)
Definition: lwlock.c:117
LWLockMode
Definition: lwlock.h:132
#define LW_FLAG_HAS_WAITERS
Definition: lwlock.c:99
static uint32 pg_atomic_sub_fetch_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:412
#define LW_LOCK_MASK
Definition: lwlock.c:106
#define LW_VAL_SHARED
Definition: lwlock.c:104
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:116
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:143
#define ERROR
Definition: elog.h:43
LWLockMode mode
Definition: lwlock.c:139
static void LWLockWakeup(LWLock *lock)
Definition: lwlock.c:865
unsigned int uint32
Definition: c.h:268
static int num_held_lwlocks
Definition: lwlock.c:142
#define Assert(condition)
Definition: c.h:675
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:227
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
int i
#define elog
Definition: elog.h:219
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
void LWLockReleaseAll ( void  )

Definition at line 1814 of file lwlock.c.

References HOLD_INTERRUPTS, LWLockRelease(), and num_held_lwlocks.

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

1815 {
1816  while (num_held_lwlocks > 0)
1817  {
1818  HOLD_INTERRUPTS(); /* match the upcoming RESUME_INTERRUPTS */
1819 
1821  }
1822 }
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:143
static int num_held_lwlocks
Definition: lwlock.c:142
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:114
void LWLockReleaseClearVar ( LWLock lock,
uint64 *  valptr,
uint64  val 
)

Definition at line 1788 of file lwlock.c.

References LWLockRelease(), LWLockWaitListLock(), LWLockWaitListUnlock(), and val.

Referenced by WALInsertLockRelease().

1789 {
1790  LWLockWaitListLock(lock);
1791 
1792  /*
1793  * Set the variable's value before releasing the lock, that prevents race
1794  * a race condition wherein a new locker acquires the lock, but hasn't yet
1795  * set the variables value.
1796  */
1797  *valptr = val;
1798  LWLockWaitListUnlock(lock);
1799 
1800  LWLockRelease(lock);
1801 }
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:852
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1715
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:800
long val
Definition: informix.c:689
static void LWLockReportWaitEnd ( void  )
inlinestatic

Definition at line 694 of file lwlock.c.

References pgstat_report_wait_end().

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

695 {
697 }
static void pgstat_report_wait_end(void)
Definition: pgstat.h:1232
static void LWLockReportWaitStart ( LWLock lock)
inlinestatic

Definition at line 685 of file lwlock.c.

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

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

686 {
688 }
uint16 tranche
Definition: lwlock.h:34
static void pgstat_report_wait_start(uint32 wait_event_info)
Definition: pgstat.h:1208
#define PG_WAIT_LWLOCK
Definition: pgstat.h:737
Size LWLockShmemSize ( void  )

Definition at line 349 of file lwlock.c.

References add_size(), i, lock_named_request_allowed, LWLOCK_PADDED_SIZE, mul_size(), NamedLWLockTrancheRequests, NUM_FIXED_LWLOCKS, and NumLWLocksByNamedTranches().

Referenced by CreateLWLocks(), and CreateSharedMemoryAndSemaphores().

350 {
351  Size size;
352  int i;
353  int numLocks = NUM_FIXED_LWLOCKS;
354 
355  numLocks += NumLWLocksByNamedTranches();
356 
357  /* Space for the LWLock array. */
358  size = mul_size(numLocks, sizeof(LWLockPadded));
359 
360  /* Space for dynamic allocation counter, plus room for alignment. */
361  size = add_size(size, sizeof(int) + LWLOCK_PADDED_SIZE);
362 
363  /* space for named tranches. */
365 
366  /* space for name of each tranche. */
367  for (i = 0; i < NamedLWLockTrancheRequests; i++)
368  size = add_size(size, strlen(NamedLWLockTrancheRequestArray[i].tranche_name) + 1);
369 
370  /* Disallow named LWLocks' requests after startup */
372 
373  return size;
374 }
static bool lock_named_request_allowed
Definition: lwlock.c:158
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:129
int NamedLWLockTrancheRequests
Definition: lwlock.c:154
Size mul_size(Size s1, Size s2)
Definition: shmem.c:492
Size add_size(Size s1, Size s2)
Definition: shmem.c:475
size_t Size
Definition: c.h:356
static int NumLWLocksByNamedTranches(void)
Definition: lwlock.c:334
NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:152
int i
#define LWLOCK_PADDED_SIZE
Definition: lwlock.h:73
void LWLockUpdateVar ( LWLock lock,
uint64 *  valptr,
uint64  val 
)

Definition at line 1661 of file lwlock.c.

References Assert, proclist_mutable_iter::cur, GetPGProcByNumber, LW_EXCLUSIVE, LW_VAL_EXCLUSIVE, LW_WAIT_UNTIL_FREE, LWLockWaitListLock(), LWLockWaitListUnlock(), PGPROC::lwWaiting, PGPROC::lwWaitMode, 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, and LWLock::waiters.

Referenced by WALInsertLockAcquireExclusive(), and WALInsertLockUpdateInsertingAt().

1662 {
1663  proclist_head wakeup;
1664  proclist_mutable_iter iter;
1665 
1666  PRINT_LWDEBUG("LWLockUpdateVar", lock, LW_EXCLUSIVE);
1667 
1668  proclist_init(&wakeup);
1669 
1670  LWLockWaitListLock(lock);
1671 
1673 
1674  /* Update the lock's value */
1675  *valptr = val;
1676 
1677  /*
1678  * See if there are any LW_WAIT_UNTIL_FREE waiters that need to be woken
1679  * up. They are always in the front of the queue.
1680  */
1681  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
1682  {
1683  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1684 
1685  if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
1686  break;
1687 
1688  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
1689  proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
1690  }
1691 
1692  /* We are done updating shared state of the lock itself. */
1693  LWLockWaitListUnlock(lock);
1694 
1695  /*
1696  * Awaken any waiters I removed from the queue.
1697  */
1698  proclist_foreach_modify(iter, &wakeup, lwWaitLink)
1699  {
1700  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1701 
1702  proclist_delete(&wakeup, iter.cur, lwWaitLink);
1703  /* check comment in LWLockWakeup() about this barrier */
1704  pg_write_barrier();
1705  waiter->lwWaiting = false;
1706  PGSemaphoreUnlock(waiter->sem);
1707  }
1708 }
#define GetPGProcByNumber(n)
Definition: proc.h:263
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
proclist_head waiters
Definition: lwlock.h:36
bool lwWaiting
Definition: proc.h:126
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:852
#define proclist_foreach_modify(iter, lhead, link_member)
Definition: proclist.h:195
uint8 lwWaitMode
Definition: proc.h:127
pg_atomic_uint32 state
Definition: lwlock.h:35
#define proclist_delete(list, procno, link_member)
Definition: proclist.h:176
#define Assert(condition)
Definition: c.h:675
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:227
#define proclist_push_tail(list, procno, link_member)
Definition: proclist.h:180
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:800
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
static void proclist_init(proclist_head *list)
Definition: proclist.h:29
#define pg_write_barrier()
Definition: atomics.h:162
PGSemaphore sem
Definition: proc.h:100
Definition: proc.h:94
long val
Definition: informix.c:689
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:252
bool LWLockWaitForVar ( LWLock lock,
uint64 *  valptr,
uint64  oldval,
uint64 *  newval 
)

Definition at line 1522 of file lwlock.c.

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

Referenced by WaitXLogInsertionsToFinish().

1523 {
1524  PGPROC *proc = MyProc;
1525  int extraWaits = 0;
1526  bool result = false;
1527 #ifdef LWLOCK_STATS
1528  lwlock_stats *lwstats;
1529 
1530  lwstats = get_lwlock_stats_entry(lock);
1531 #endif
1532 
1533  PRINT_LWDEBUG("LWLockWaitForVar", lock, LW_WAIT_UNTIL_FREE);
1534 
1535  /*
1536  * Lock out cancel/die interrupts while we sleep on the lock. There is no
1537  * cleanup mechanism to remove us from the wait queue if we got
1538  * interrupted.
1539  */
1540  HOLD_INTERRUPTS();
1541 
1542  /*
1543  * Loop here to check the lock's status after each time we are signaled.
1544  */
1545  for (;;)
1546  {
1547  bool mustwait;
1548 
1549  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1550  &result);
1551 
1552  if (!mustwait)
1553  break; /* the lock was free or value didn't match */
1554 
1555  /*
1556  * Add myself to wait queue. Note that this is racy, somebody else
1557  * could wakeup before we're finished queuing. NB: We're using nearly
1558  * the same twice-in-a-row lock acquisition protocol as
1559  * LWLockAcquire(). Check its comments for details. The only
1560  * difference is that we also have to check the variable's values when
1561  * checking the state of the lock.
1562  */
1564 
1565  /*
1566  * Set RELEASE_OK flag, to make sure we get woken up as soon as the
1567  * lock is released.
1568  */
1570 
1571  /*
1572  * We're now guaranteed to be woken up if necessary. Recheck the lock
1573  * and variables state.
1574  */
1575  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1576  &result);
1577 
1578  /* Ok, no conflict after we queued ourselves. Undo queueing. */
1579  if (!mustwait)
1580  {
1581  LOG_LWDEBUG("LWLockWaitForVar", lock, "free, undoing queue");
1582 
1583  LWLockDequeueSelf(lock);
1584  break;
1585  }
1586 
1587  /*
1588  * Wait until awakened.
1589  *
1590  * Since we share the process wait semaphore with the regular lock
1591  * manager and ProcWaitForSignal, and we may need to acquire an LWLock
1592  * while one of those is pending, it is possible that we get awakened
1593  * for a reason other than being signaled by LWLockRelease. If so,
1594  * loop back and wait again. Once we've gotten the LWLock,
1595  * re-increment the sema by the number of additional signals received,
1596  * so that the lock manager or signal manager will see the received
1597  * signal when it next waits.
1598  */
1599  LOG_LWDEBUG("LWLockWaitForVar", lock, "waiting");
1600 
1601 #ifdef LWLOCK_STATS
1602  lwstats->block_count++;
1603 #endif
1604 
1605  LWLockReportWaitStart(lock);
1606  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE);
1607 
1608  for (;;)
1609  {
1610  PGSemaphoreLock(proc->sem);
1611  if (!proc->lwWaiting)
1612  break;
1613  extraWaits++;
1614  }
1615 
1616 #ifdef LOCK_DEBUG
1617  {
1618  /* not waiting anymore */
1619  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1620 
1621  Assert(nwaiters < MAX_BACKENDS);
1622  }
1623 #endif
1624 
1625  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE);
1627 
1628  LOG_LWDEBUG("LWLockWaitForVar", lock, "awakened");
1629 
1630  /* Now loop back and check the status of the lock again. */
1631  }
1632 
1633  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), LW_EXCLUSIVE);
1634 
1635  /*
1636  * Fix the process wait semaphore's count for any absorbed wakeups.
1637  */
1638  while (extraWaits-- > 0)
1639  PGSemaphoreUnlock(proc->sem);
1640 
1641  /*
1642  * Now okay to allow cancel/die interrupts.
1643  */
1645 
1646  return result;
1647 }
#define T_NAME(lock)
Definition: lwlock.c:117
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:354
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
PGPROC * MyProc
Definition: proc.c:67
bool lwWaiting
Definition: proc.h:126
return result
Definition: formatting.c:1618
pg_atomic_uint32 state
Definition: lwlock.h:35
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:116
#define MAX_BACKENDS
Definition: postmaster.h:75
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:694
unsigned int uint32
Definition: c.h:268
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1016
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:685
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:972
#define Assert(condition)
Definition: c.h:675
#define newval
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:227
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:303
static bool LWLockConflictsWithVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval, bool *result)
Definition: lwlock.c:1462
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:114
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:383
PGSemaphore sem
Definition: proc.h:100
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:990
Definition: proc.h:94
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
static void LWLockWaitListLock ( LWLock lock)
static

Definition at line 800 of file lwlock.c.

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 LWLockConflictsWithVar(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReleaseClearVar(), LWLockUpdateVar(), and LWLockWakeup().

801 {
802  uint32 old_state;
803 #ifdef LWLOCK_STATS
804  lwlock_stats *lwstats;
805  uint32 delays = 0;
806 
807  lwstats = get_lwlock_stats_entry(lock);
808 #endif
809 
810  while (true)
811  {
812  /* always try once to acquire lock directly */
813  old_state = pg_atomic_fetch_or_u32(&lock->state, LW_FLAG_LOCKED);
814  if (!(old_state & LW_FLAG_LOCKED))
815  break; /* got lock */
816 
817  /* and then spin without atomic operations until lock is released */
818  {
819  SpinDelayStatus delayStatus;
820 
821  init_local_spin_delay(&delayStatus);
822 
823  while (old_state & LW_FLAG_LOCKED)
824  {
825  perform_spin_delay(&delayStatus);
826  old_state = pg_atomic_read_u32(&lock->state);
827  }
828 #ifdef LWLOCK_STATS
829  delays += delayStatus.delays;
830 #endif
831  finish_spin_delay(&delayStatus);
832  }
833 
834  /*
835  * Retry. The lock might obviously already be re-acquired by the time
836  * we're attempting to get it again.
837  */
838  }
839 
840 #ifdef LWLOCK_STATS
841  lwstats->spin_delay_count += delays;
842 #endif
843 }
#define init_local_spin_delay(status)
Definition: s_lock.h:997
#define LW_FLAG_LOCKED
Definition: lwlock.c:101
pg_atomic_uint32 state
Definition: lwlock.h:35
void finish_spin_delay(SpinDelayStatus *status)
Definition: s_lock.c:175
unsigned int uint32
Definition: c.h:268
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:383
void perform_spin_delay(SpinDelayStatus *status)
Definition: s_lock.c:125
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:252
static void LWLockWaitListUnlock ( LWLock lock)
static

Definition at line 852 of file lwlock.c.

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

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

853 {
855 
856  old_state = pg_atomic_fetch_and_u32(&lock->state, ~LW_FLAG_LOCKED);
857 
858  Assert(old_state & LW_FLAG_LOCKED);
859 }
#define LW_FLAG_LOCKED
Definition: lwlock.c:101
pg_atomic_uint32 state
Definition: lwlock.h:35
static uint32 pg_atomic_fetch_and_u32(volatile pg_atomic_uint32 *ptr, uint32 and_)
Definition: atomics.h:369
unsigned int uint32
Definition: c.h:268
#define Assert(condition)
Definition: c.h:675
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:990
static void LWLockWakeup ( LWLock lock)
static

Definition at line 865 of file lwlock.c.

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, 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, and LWLock::waiters.

Referenced by LWLockRelease().

866 {
867  bool new_release_ok;
868  bool wokeup_somebody = false;
869  proclist_head wakeup;
871 
872  proclist_init(&wakeup);
873 
874  new_release_ok = true;
875 
876  /* lock wait list while collecting backends to wake up */
877  LWLockWaitListLock(lock);
878 
879  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
880  {
881  PGPROC *waiter = GetPGProcByNumber(iter.cur);
882 
883  if (wokeup_somebody && waiter->lwWaitMode == LW_EXCLUSIVE)
884  continue;
885 
886  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
887  proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
888 
889  if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
890  {
891  /*
892  * Prevent additional wakeups until retryer gets to run. Backends
893  * that are just waiting for the lock to become free don't retry
894  * automatically.
895  */
896  new_release_ok = false;
897 
898  /*
899  * Don't wakeup (further) exclusive locks.
900  */
901  wokeup_somebody = true;
902  }
903 
904  /*
905  * Once we've woken up an exclusive lock, there's no point in waking
906  * up anybody else.
907  */
908  if (waiter->lwWaitMode == LW_EXCLUSIVE)
909  break;
910  }
911 
913 
914  /* unset required flags, and release lock, in one fell swoop */
915  {
916  uint32 old_state;
917  uint32 desired_state;
918 
919  old_state = pg_atomic_read_u32(&lock->state);
920  while (true)
921  {
922  desired_state = old_state;
923 
924  /* compute desired flags */
925 
926  if (new_release_ok)
927  desired_state |= LW_FLAG_RELEASE_OK;
928  else
929  desired_state &= ~LW_FLAG_RELEASE_OK;
930 
931  if (proclist_is_empty(&wakeup))
932  desired_state &= ~LW_FLAG_HAS_WAITERS;
933 
934  desired_state &= ~LW_FLAG_LOCKED; /* release lock */
935 
936  if (pg_atomic_compare_exchange_u32(&lock->state, &old_state,
937  desired_state))
938  break;
939  }
940  }
941 
942  /* Awaken any waiters I removed from the queue. */
943  proclist_foreach_modify(iter, &wakeup, lwWaitLink)
944  {
945  PGPROC *waiter = GetPGProcByNumber(iter.cur);
946 
947  LOG_LWDEBUG("LWLockRelease", lock, "release waiter");
948  proclist_delete(&wakeup, iter.cur, lwWaitLink);
949 
950  /*
951  * Guarantee that lwWaiting being unset only becomes visible once the
952  * unlink from the link has completed. Otherwise the target backend
953  * could be woken up for other reason and enqueue for a new lock - if
954  * that happens before the list unlink happens, the list would end up
955  * being corrupted.
956  *
957  * The barrier pairs with the LWLockWaitListLock() when enqueuing for
958  * another lock.
959  */
961  waiter->lwWaiting = false;
962  PGSemaphoreUnlock(waiter->sem);
963  }
964 }
#define GetPGProcByNumber(n)
Definition: proc.h:263
#define LW_FLAG_LOCKED
Definition: lwlock.c:101
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
#define LW_FLAG_HAS_WAITERS
Definition: lwlock.c:99
static bool pg_atomic_compare_exchange_u32(volatile pg_atomic_uint32 *ptr, uint32 *expected, uint32 newval)
Definition: atomics.h:322
proclist_head waiters
Definition: lwlock.h:36
bool lwWaiting
Definition: proc.h:126
#define proclist_foreach_modify(iter, lhead, link_member)
Definition: proclist.h:195
uint8 lwWaitMode
Definition: proc.h:127
pg_atomic_uint32 state
Definition: lwlock.h:35
#define proclist_delete(list, procno, link_member)
Definition: proclist.h:176
unsigned int uint32
Definition: c.h:268
#define Assert(condition)
Definition: c.h:675
static bool proclist_is_empty(proclist_head *list)
Definition: proclist.h:38
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
#define proclist_push_tail(list, procno, link_member)
Definition: proclist.h:180
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:800
static void proclist_init(proclist_head *list)
Definition: proclist.h:29
#define pg_write_barrier()
Definition: atomics.h:162
PGSemaphore sem
Definition: proc.h:100
Definition: proc.h:94
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:252
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
static int NumLWLocksByNamedTranches ( void  )
static

Definition at line 334 of file lwlock.c.

References i, and NamedLWLockTrancheRequests.

Referenced by InitializeLWLocks(), and LWLockShmemSize().

335 {
336  int numLocks = 0;
337  int i;
338 
339  for (i = 0; i < NamedLWLockTrancheRequests; i++)
340  numLocks += NamedLWLockTrancheRequestArray[i].num_lwlocks;
341 
342  return numLocks;
343 }
int NamedLWLockTrancheRequests
Definition: lwlock.c:154
NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:152
int i
static void RegisterLWLockTranches ( void  )
static

Definition at line 491 of file lwlock.c.

References Assert, i, LWLockRegisterTranche(), LWLockTrancheArray, LWLockTranchesAllocated, LWTRANCHE_BUFFER_MAPPING, LWTRANCHE_FIRST_USER_DEFINED, LWTRANCHE_LOCK_MANAGER, LWTRANCHE_PARALLEL_QUERY_DSA, LWTRANCHE_PREDICATE_LOCK_MANAGER, LWTRANCHE_TBM, MainLWLockNames, MemoryContextAllocZero(), NamedLWLockTrancheRequests, NULL, and TopMemoryContext.

Referenced by CreateLWLocks().

492 {
493  int i;
494 
495  if (LWLockTrancheArray == NULL)
496  {
498  LWLockTrancheArray = (char **)
500  LWLockTranchesAllocated * sizeof(char *));
502  }
503 
504  for (i = 0; i < NUM_INDIVIDUAL_LWLOCKS; ++i)
506 
510  "predicate_lock_manager");
512  "parallel_query_dsa");
514 
515  /* Register named tranches. */
516  for (i = 0; i < NamedLWLockTrancheRequests; i++)
518  NamedLWLockTrancheArray[i].trancheName);
519 }
NamedLWLockTranche * NamedLWLockTrancheArray
Definition: lwlock.c:156
static int LWLockTranchesAllocated
Definition: lwlock.c:115
int NamedLWLockTrancheRequests
Definition: lwlock.c:154
MemoryContext TopMemoryContext
Definition: mcxt.c:43
void * MemoryContextAllocZero(MemoryContext context, Size size)
Definition: mcxt.c:742
static char ** LWLockTrancheArray
Definition: lwlock.c:114
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
void LWLockRegisterTranche(int tranche_id, char *tranche_name)
Definition: lwlock.c:592
char * MainLWLockNames[]
int i
void RequestNamedLWLockTranche ( const char *  tranche_name,
int  num_lwlocks 
)

Definition at line 627 of file lwlock.c.

References Assert, i, IsUnderPostmaster, lock_named_request_allowed, MemoryContextAlloc(), NAMEDATALEN, NamedLWLockTrancheRequests, NamedLWLockTrancheRequestsAllocated, NULL, NamedLWLockTrancheRequest::num_lwlocks, repalloc(), StrNCpy, TopMemoryContext, and NamedLWLockTrancheRequest::tranche_name.

Referenced by _PG_init().

628 {
629  NamedLWLockTrancheRequest *request;
630 
632  return; /* too late */
633 
635  {
640  * sizeof(NamedLWLockTrancheRequest));
641  }
642 
644  {
646 
647  while (i <= NamedLWLockTrancheRequests)
648  i *= 2;
649 
652  i * sizeof(NamedLWLockTrancheRequest));
654  }
655 
657  Assert(strlen(tranche_name) + 1 < NAMEDATALEN);
658  StrNCpy(request->tranche_name, tranche_name, NAMEDATALEN);
659  request->num_lwlocks = num_lwlocks;
661 }
static bool lock_named_request_allowed
Definition: lwlock.c:158
char tranche_name[NAMEDATALEN]
Definition: lwlock.c:148
#define NAMEDATALEN
int NamedLWLockTrancheRequests
Definition: lwlock.c:154
bool IsUnderPostmaster
Definition: globals.c:100
MemoryContext TopMemoryContext
Definition: mcxt.c:43
static int NamedLWLockTrancheRequestsAllocated
Definition: lwlock.c:153
#define NULL
Definition: c.h:229
#define Assert(condition)
Definition: c.h:675
#define StrNCpy(dst, src, len)
Definition: c.h:830
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:963
NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:152
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:707
int i

Variable Documentation

LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
static

Definition at line 143 of file lwlock.c.

bool lock_named_request_allowed = true
static

Definition at line 158 of file lwlock.c.

Referenced by LWLockShmemSize(), and RequestNamedLWLockTranche().

char** LWLockTrancheArray = NULL
static

Definition at line 114 of file lwlock.c.

Referenced by GetLWLockIdentifier(), LWLockRegisterTranche(), and RegisterLWLockTranches().

int LWLockTranchesAllocated = 0
static

Definition at line 115 of file lwlock.c.

Referenced by GetLWLockIdentifier(), LWLockRegisterTranche(), and RegisterLWLockTranches().

LWLockPadded* MainLWLockArray = NULL

Definition at line 125 of file lwlock.c.

NamedLWLockTranche* NamedLWLockTrancheArray = NULL

Definition at line 156 of file lwlock.c.

NamedLWLockTrancheRequest* NamedLWLockTrancheRequestArray = NULL

Definition at line 152 of file lwlock.c.

int NamedLWLockTrancheRequestsAllocated = 0
static

Definition at line 153 of file lwlock.c.

Referenced by RequestNamedLWLockTranche().

slock_t* ShmemLock

Definition at line 84 of file shmem.c.

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