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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:101
unsigned int uint32
Definition: c.h:258
static void InitializeLWLocks(void)
Definition: lwlock.c:426
#define StaticAssertExpr(condition, errmessage)
Definition: c.h:765
size_t Size
Definition: c.h:350
#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 709 of file lwlock.c.

References Assert, LWLockTrancheArray, LWLockTranchesAllocated, and PG_WAIT_LWLOCK.

Referenced by pgstat_get_wait_event().

710 {
711  Assert(classId == PG_WAIT_LWLOCK);
712 
713  /*
714  * It is quite possible that user has registered tranche in one of the
715  * backends (e.g. by allocating lwlocks in dynamic shared memory) but not
716  * all of them, so we can't assume the tranche is registered here.
717  */
718  if (eventId >= LWLockTranchesAllocated ||
719  LWLockTrancheArray[eventId] == NULL)
720  return "extension";
721 
722  return LWLockTrancheArray[eventId];
723 }
static int LWLockTranchesAllocated
Definition: lwlock.c:115
static char ** LWLockTrancheArray
Definition: lwlock.c:114
#define Assert(condition)
Definition: c.h:681
#define PG_WAIT_LWLOCK
Definition: pgstat.h:737
LWLockPadded* GetNamedLWLockTranche ( const char *  tranche_name)

Definition at line 547 of file lwlock.c.

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

Referenced by pgss_shmem_startup().

548 {
549  int lock_pos;
550  int i;
551 
552  /*
553  * Obtain the position of base address of LWLock belonging to requested
554  * tranche_name in MainLWLockArray. LWLocks for named tranches are placed
555  * in MainLWLockArray after fixed locks.
556  */
557  lock_pos = NUM_FIXED_LWLOCKS;
558  for (i = 0; i < NamedLWLockTrancheRequests; i++)
559  {
560  if (strcmp(NamedLWLockTrancheRequestArray[i].tranche_name,
561  tranche_name) == 0)
562  return &MainLWLockArray[lock_pos];
563 
565  }
566 
567  if (i >= NamedLWLockTrancheRequests)
568  elog(ERROR, "requested tranche is not registered");
569 
570  /* just to keep compiler quiet */
571  return NULL;
572 }
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:129
#define ERROR
Definition: elog.h:43
int NamedLWLockTrancheRequests
Definition: lwlock.c:154
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:578
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:673
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 531 of file lwlock.c.

Referenced by InitProcess().

532 {
533 #ifdef LWLOCK_STATS
534  init_lwlock_stats();
535 #endif
536 }
bool LWLockAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1117 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, 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(), AbortBufferIO(), AbsorbFsyncRequests(), ActivateCommitTs(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), analyze_rel(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_init_shmem(), apw_load_buffers(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AsyncShmemInit(), AtAbort_Twophase(), AtPrepare_PredicateLocks(), attach_internal(), autoprewarm_main(), autoprewarm_start_worker(), 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(), DropSubscription(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), 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(), 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(), FinishPreparedTransaction(), FlushDatabaseBuffers(), FlushRelationBuffers(), ForceTransactionIdLimitUpdate(), ForwardFsyncRequest(), FreeWorkerInfo(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), 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_get_replication_slots(), 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(), 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(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquire(), ReplicationSlotCleanup(), 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(), resize(), RestoreScratchTarget(), restoreTwoPhaseData(), 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(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdLimitedForOldSnapshots(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), txid_status(), UpdateMinRecoveryPoint(), vacuum_rel(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_relation_state_change(), wait_for_worker_state_change(), WaitForReplicationWorkerAttach(), WaitIO(), WALInsertLockAcquire(), WALInsertLockAcquireExclusive(), write_relcache_init_file(), xact_redo(), xact_redo_abort(), xact_redo_commit(), XidCacheRemoveRunningXids(), xlog_redo(), and XLogBackgroundFlush().

1118 {
1119  PGPROC *proc = MyProc;
1120  bool result = true;
1121  int extraWaits = 0;
1122 #ifdef LWLOCK_STATS
1123  lwlock_stats *lwstats;
1124 
1125  lwstats = get_lwlock_stats_entry(lock);
1126 #endif
1127 
1128  AssertArg(mode == LW_SHARED || mode == LW_EXCLUSIVE);
1129 
1130  PRINT_LWDEBUG("LWLockAcquire", lock, mode);
1131 
1132 #ifdef LWLOCK_STATS
1133  /* Count lock acquisition attempts */
1134  if (mode == LW_EXCLUSIVE)
1135  lwstats->ex_acquire_count++;
1136  else
1137  lwstats->sh_acquire_count++;
1138 #endif /* LWLOCK_STATS */
1139 
1140  /*
1141  * We can't wait if we haven't got a PGPROC. This should only occur
1142  * during bootstrap or shared memory initialization. Put an Assert here
1143  * to catch unsafe coding practices.
1144  */
1145  Assert(!(proc == NULL && IsUnderPostmaster));
1146 
1147  /* Ensure we will have room to remember the lock */
1149  elog(ERROR, "too many LWLocks taken");
1150 
1151  /*
1152  * Lock out cancel/die interrupts until we exit the code section protected
1153  * by the LWLock. This ensures that interrupts will not interfere with
1154  * manipulations of data structures in shared memory.
1155  */
1156  HOLD_INTERRUPTS();
1157 
1158  /*
1159  * Loop here to try to acquire lock after each time we are signaled by
1160  * LWLockRelease.
1161  *
1162  * NOTE: it might seem better to have LWLockRelease actually grant us the
1163  * lock, rather than retrying and possibly having to go back to sleep. But
1164  * in practice that is no good because it means a process swap for every
1165  * lock acquisition when two or more processes are contending for the same
1166  * lock. Since LWLocks are normally used to protect not-very-long
1167  * sections of computation, a process needs to be able to acquire and
1168  * release the same lock many times during a single CPU time slice, even
1169  * in the presence of contention. The efficiency of being able to do that
1170  * outweighs the inefficiency of sometimes wasting a process dispatch
1171  * cycle because the lock is not free when a released waiter finally gets
1172  * to run. See pgsql-hackers archives for 29-Dec-01.
1173  */
1174  for (;;)
1175  {
1176  bool mustwait;
1177 
1178  /*
1179  * Try to grab the lock the first time, we're not in the waitqueue
1180  * yet/anymore.
1181  */
1182  mustwait = LWLockAttemptLock(lock, mode);
1183 
1184  if (!mustwait)
1185  {
1186  LOG_LWDEBUG("LWLockAcquire", lock, "immediately acquired lock");
1187  break; /* got the lock */
1188  }
1189 
1190  /*
1191  * Ok, at this point we couldn't grab the lock on the first try. We
1192  * cannot simply queue ourselves to the end of the list and wait to be
1193  * woken up because by now the lock could long have been released.
1194  * Instead add us to the queue and try to grab the lock again. If we
1195  * succeed we need to revert the queuing and be happy, otherwise we
1196  * recheck the lock. If we still couldn't grab it, we know that the
1197  * other locker will see our queue entries when releasing since they
1198  * existed before we checked for the lock.
1199  */
1200 
1201  /* add to the queue */
1202  LWLockQueueSelf(lock, mode);
1203 
1204  /* we're now guaranteed to be woken up if necessary */
1205  mustwait = LWLockAttemptLock(lock, mode);
1206 
1207  /* ok, grabbed the lock the second time round, need to undo queueing */
1208  if (!mustwait)
1209  {
1210  LOG_LWDEBUG("LWLockAcquire", lock, "acquired, undoing queue");
1211 
1212  LWLockDequeueSelf(lock);
1213  break;
1214  }
1215 
1216  /*
1217  * Wait until awakened.
1218  *
1219  * Since we share the process wait semaphore with the regular lock
1220  * manager and ProcWaitForSignal, and we may need to acquire an LWLock
1221  * while one of those is pending, it is possible that we get awakened
1222  * for a reason other than being signaled by LWLockRelease. If so,
1223  * loop back and wait again. Once we've gotten the LWLock,
1224  * re-increment the sema by the number of additional signals received,
1225  * so that the lock manager or signal manager will see the received
1226  * signal when it next waits.
1227  */
1228  LOG_LWDEBUG("LWLockAcquire", lock, "waiting");
1229 
1230 #ifdef LWLOCK_STATS
1231  lwstats->block_count++;
1232 #endif
1233 
1234  LWLockReportWaitStart(lock);
1235  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1236 
1237  for (;;)
1238  {
1239  PGSemaphoreLock(proc->sem);
1240  if (!proc->lwWaiting)
1241  break;
1242  extraWaits++;
1243  }
1244 
1245  /* Retrying, allow LWLockRelease to release waiters again. */
1247 
1248 #ifdef LOCK_DEBUG
1249  {
1250  /* not waiting anymore */
1251  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1252 
1253  Assert(nwaiters < MAX_BACKENDS);
1254  }
1255 #endif
1256 
1257  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1259 
1260  LOG_LWDEBUG("LWLockAcquire", lock, "awakened");
1261 
1262  /* Now loop back and try to acquire lock again. */
1263  result = false;
1264  }
1265 
1266  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode);
1267 
1268  /* Add lock to list of locks held by this backend */
1271 
1272  /*
1273  * Fix the process wait semaphore's count for any absorbed wakeups.
1274  */
1275  while (extraWaits-- > 0)
1276  PGSemaphoreUnlock(proc->sem);
1277 
1278  return result;
1279 }
#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:735
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
PGPROC * MyProc
Definition: proc.c:67
bool lwWaiting
Definition: proc.h:127
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:133
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:101
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:700
unsigned int uint32
Definition: c.h:258
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1022
#define AssertArg(condition)
Definition: c.h:683
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:691
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:978
static int num_held_lwlocks
Definition: lwlock.c:142
#define Assert(condition)
Definition: c.h:681
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:115
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:101
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:996
Definition: proc.h:95
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
bool LWLockAcquireOrWait ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1344 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().

1345 {
1346  PGPROC *proc = MyProc;
1347  bool mustwait;
1348  int extraWaits = 0;
1349 #ifdef LWLOCK_STATS
1350  lwlock_stats *lwstats;
1351 
1352  lwstats = get_lwlock_stats_entry(lock);
1353 #endif
1354 
1355  Assert(mode == LW_SHARED || mode == LW_EXCLUSIVE);
1356 
1357  PRINT_LWDEBUG("LWLockAcquireOrWait", lock, mode);
1358 
1359  /* Ensure we will have room to remember the lock */
1361  elog(ERROR, "too many LWLocks taken");
1362 
1363  /*
1364  * Lock out cancel/die interrupts until we exit the code section protected
1365  * by the LWLock. This ensures that interrupts will not interfere with
1366  * manipulations of data structures in shared memory.
1367  */
1368  HOLD_INTERRUPTS();
1369 
1370  /*
1371  * NB: We're using nearly the same twice-in-a-row lock acquisition
1372  * protocol as LWLockAcquire(). Check its comments for details.
1373  */
1374  mustwait = LWLockAttemptLock(lock, mode);
1375 
1376  if (mustwait)
1377  {
1379 
1380  mustwait = LWLockAttemptLock(lock, mode);
1381 
1382  if (mustwait)
1383  {
1384  /*
1385  * Wait until awakened. Like in LWLockAcquire, be prepared for
1386  * bogus wakeups, because we share the semaphore with
1387  * ProcWaitForSignal.
1388  */
1389  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "waiting");
1390 
1391 #ifdef LWLOCK_STATS
1392  lwstats->block_count++;
1393 #endif
1394 
1395  LWLockReportWaitStart(lock);
1396  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1397 
1398  for (;;)
1399  {
1400  PGSemaphoreLock(proc->sem);
1401  if (!proc->lwWaiting)
1402  break;
1403  extraWaits++;
1404  }
1405 
1406 #ifdef LOCK_DEBUG
1407  {
1408  /* not waiting anymore */
1409  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1410 
1411  Assert(nwaiters < MAX_BACKENDS);
1412  }
1413 #endif
1414  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1416 
1417  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "awakened");
1418  }
1419  else
1420  {
1421  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "acquired, undoing queue");
1422 
1423  /*
1424  * Got lock in the second attempt, undo queueing. We need to treat
1425  * this as having successfully acquired the lock, otherwise we'd
1426  * not necessarily wake up people we've prevented from acquiring
1427  * the lock.
1428  */
1429  LWLockDequeueSelf(lock);
1430  }
1431  }
1432 
1433  /*
1434  * Fix the process wait semaphore's count for any absorbed wakeups.
1435  */
1436  while (extraWaits-- > 0)
1437  PGSemaphoreUnlock(proc->sem);
1438 
1439  if (mustwait)
1440  {
1441  /* Failed to get lock, so release interrupt holdoff */
1443  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "failed");
1444  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode);
1445  }
1446  else
1447  {
1448  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "succeeded");
1449  /* Add lock to list of locks held by this backend */
1452  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode);
1453  }
1454 
1455  return !mustwait;
1456 }
#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:735
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
PGPROC * MyProc
Definition: proc.c:67
bool lwWaiting
Definition: proc.h:127
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:133
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:117
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:700
unsigned int uint32
Definition: c.h:258
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1022
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:691
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:978
static int num_held_lwlocks
Definition: lwlock.c:142
#define Assert(condition)
Definition: c.h:681
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:115
#define elog
Definition: elog.h:219
PGSemaphore sem
Definition: proc.h:101
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:996
Definition: proc.h:95
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
static bool LWLockAttemptLock ( LWLock lock,
LWLockMode  mode 
)
static

Definition at line 735 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().

736 {
737  uint32 old_state;
738 
739  AssertArg(mode == LW_EXCLUSIVE || mode == LW_SHARED);
740 
741  /*
742  * Read once outside the loop, later iterations will get the newer value
743  * via compare & exchange.
744  */
745  old_state = pg_atomic_read_u32(&lock->state);
746 
747  /* loop until we've determined whether we could acquire the lock or not */
748  while (true)
749  {
750  uint32 desired_state;
751  bool lock_free;
752 
753  desired_state = old_state;
754 
755  if (mode == LW_EXCLUSIVE)
756  {
757  lock_free = (old_state & LW_LOCK_MASK) == 0;
758  if (lock_free)
759  desired_state += LW_VAL_EXCLUSIVE;
760  }
761  else
762  {
763  lock_free = (old_state & LW_VAL_EXCLUSIVE) == 0;
764  if (lock_free)
765  desired_state += LW_VAL_SHARED;
766  }
767 
768  /*
769  * Attempt to swap in the state we are expecting. If we didn't see
770  * lock to be free, that's just the old value. If we saw it as free,
771  * we'll attempt to mark it acquired. The reason that we always swap
772  * in the value is that this doubles as a memory barrier. We could try
773  * to be smarter and only swap in values if we saw the lock as free,
774  * but benchmark haven't shown it as beneficial so far.
775  *
776  * Retry if the value changed since we last looked at it.
777  */
779  &old_state, desired_state))
780  {
781  if (lock_free)
782  {
783  /* Great! Got the lock. */
784 #ifdef LOCK_DEBUG
785  if (mode == LW_EXCLUSIVE)
786  lock->owner = MyProc;
787 #endif
788  return false;
789  }
790  else
791  return true; /* somebody else has the lock */
792  }
793  }
794  pg_unreachable();
795 }
#define pg_unreachable()
Definition: c.h:952
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:258
#define AssertArg(condition)
Definition: c.h:683
#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 1289 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(), TransactionIdSetPageStatus(), and XLogNeedsFlush().

1290 {
1291  bool mustwait;
1292 
1293  AssertArg(mode == LW_SHARED || mode == LW_EXCLUSIVE);
1294 
1295  PRINT_LWDEBUG("LWLockConditionalAcquire", lock, mode);
1296 
1297  /* Ensure we will have room to remember the lock */
1299  elog(ERROR, "too many LWLocks taken");
1300 
1301  /*
1302  * Lock out cancel/die interrupts until we exit the code section protected
1303  * by the LWLock. This ensures that interrupts will not interfere with
1304  * manipulations of data structures in shared memory.
1305  */
1306  HOLD_INTERRUPTS();
1307 
1308  /* Check for the lock */
1309  mustwait = LWLockAttemptLock(lock, mode);
1310 
1311  if (mustwait)
1312  {
1313  /* Failed to get lock, so release interrupt holdoff */
1315 
1316  LOG_LWDEBUG("LWLockConditionalAcquire", lock, "failed");
1317  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode);
1318  }
1319  else
1320  {
1321  /* Add lock to list of locks held by this backend */
1324  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode);
1325  }
1326  return !mustwait;
1327 }
#define T_NAME(lock)
Definition: lwlock.c:117
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:735
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:133
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:117
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:683
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:115
#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 1468 of file lwlock.c.

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

Referenced by LWLockWaitForVar().

1471 {
1472  bool mustwait;
1473  uint64 value;
1474 
1475  /*
1476  * Test first to see if it the slot is free right now.
1477  *
1478  * XXX: the caller uses a spinlock before this, so we don't need a memory
1479  * barrier here as far as the current usage is concerned. But that might
1480  * not be safe in general.
1481  */
1482  mustwait = (pg_atomic_read_u32(&lock->state) & LW_VAL_EXCLUSIVE) != 0;
1483 
1484  if (!mustwait)
1485  {
1486  *result = true;
1487  return false;
1488  }
1489 
1490  *result = false;
1491 
1492  /*
1493  * Read value using the lwlock's wait list lock, as we can't generally
1494  * rely on atomic 64 bit reads/stores. TODO: On platforms with a way to
1495  * do atomic 64 bit reads/writes the spinlock should be optimized away.
1496  */
1497  LWLockWaitListLock(lock);
1498  value = *valptr;
1499  LWLockWaitListUnlock(lock);
1500 
1501  if (value != oldval)
1502  {
1503  mustwait = false;
1504  *newval = value;
1505  }
1506  else
1507  {
1508  mustwait = true;
1509  }
1510 
1511  return mustwait;
1512 }
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:858
pg_atomic_uint32 state
Definition: lwlock.h:35
static struct @121 value
#define newval
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:806
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:252
static void LWLockDequeueSelf ( LWLock lock)
static

Definition at line 1022 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().

1023 {
1024  bool found = false;
1025  proclist_mutable_iter iter;
1026 
1027 #ifdef LWLOCK_STATS
1028  lwlock_stats *lwstats;
1029 
1030  lwstats = get_lwlock_stats_entry(lock);
1031 
1032  lwstats->dequeue_self_count++;
1033 #endif
1034 
1035  LWLockWaitListLock(lock);
1036 
1037  /*
1038  * Can't just remove ourselves from the list, but we need to iterate over
1039  * all entries as somebody else could have dequeued us.
1040  */
1041  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
1042  {
1043  if (iter.cur == MyProc->pgprocno)
1044  {
1045  found = true;
1046  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
1047  break;
1048  }
1049  }
1050 
1051  if (proclist_is_empty(&lock->waiters) &&
1052  (pg_atomic_read_u32(&lock->state) & LW_FLAG_HAS_WAITERS) != 0)
1053  {
1055  }
1056 
1057  /* XXX: combine with fetch_and above? */
1058  LWLockWaitListUnlock(lock);
1059 
1060  /* clear waiting state again, nice for debugging */
1061  if (found)
1062  MyProc->lwWaiting = false;
1063  else
1064  {
1065  int extraWaits = 0;
1066 
1067  /*
1068  * Somebody else dequeued us and has or will wake us up. Deal with the
1069  * superfluous absorption of a wakeup.
1070  */
1071 
1072  /*
1073  * Reset releaseOk if somebody woke us before we removed ourselves -
1074  * they'll have set it to false.
1075  */
1077 
1078  /*
1079  * Now wait for the scheduled wakeup, otherwise our ->lwWaiting would
1080  * get reset at some inconvenient point later. Most of the time this
1081  * will immediately return.
1082  */
1083  for (;;)
1084  {
1086  if (!MyProc->lwWaiting)
1087  break;
1088  extraWaits++;
1089  }
1090 
1091  /*
1092  * Fix the process wait semaphore's count for any absorbed wakeups.
1093  */
1094  while (extraWaits-- > 0)
1096  }
1097 
1098 #ifdef LOCK_DEBUG
1099  {
1100  /* not waiting anymore */
1101  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1102 
1103  Assert(nwaiters < MAX_BACKENDS);
1104  }
1105 #endif
1106 }
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:127
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:858
#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:258
#define Assert(condition)
Definition: c.h:681
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:806
int pgprocno
Definition: proc.h:110
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:383
PGSemaphore sem
Definition: proc.h:101
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:996
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:252
bool LWLockHeldByMeInMode ( LWLock l,
LWLockMode  mode 
)

Definition at line 1855 of file lwlock.c.

References i, and num_held_lwlocks.

Referenced by dshash_delete_entry(), dshash_release_lock(), IsBufferCleanupOK(), logicalrep_worker_cleanup(), MarkAsPreparingGuts(), MarkBufferDirty(), PrepareRedoAdd(), PrepareRedoRemove(), ProcessTwoPhaseBuffer(), RemoveGXact(), and TransactionIdSetPageStatusInternal().

1856 {
1857  int i;
1858 
1859  for (i = 0; i < num_held_lwlocks; i++)
1860  {
1861  if (held_lwlocks[i].lock == l && held_lwlocks[i].mode == mode)
1862  return true;
1863  }
1864  return false;
1865 }
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 673 of file lwlock.c.

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

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

674 {
676 #ifdef LOCK_DEBUG
677  pg_atomic_init_u32(&lock->nwaiters, 0);
678 #endif
679  lock->tranche = tranche_id;
680  proclist_init(&lock->waiters);
681 }
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 578 of file lwlock.c.

References ShmemLock, SpinLockAcquire, and SpinLockRelease.

Referenced by apw_init_shmem(), and InitializeLWLocks().

579 {
580  int result;
581  int *LWLockCounter;
582 
583  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
585  result = (*LWLockCounter)++;
587 
588  return result;
589 }
#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 978 of file lwlock.c.

References elog, LW_FLAG_HAS_WAITERS, LW_WAIT_UNTIL_FREE, LWLockWaitListLock(), LWLockWaitListUnlock(), PGPROC::lwWaiting, PGPROC::lwWaitMode, MyProc, 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().

979 {
980  /*
981  * If we don't have a PGPROC structure, there's no way to wait. This
982  * should never occur, since MyProc should only be null during shared
983  * memory initialization.
984  */
985  if (MyProc == NULL)
986  elog(PANIC, "cannot wait without a PGPROC structure");
987 
988  if (MyProc->lwWaiting)
989  elog(PANIC, "queueing for lock while waiting on another one");
990 
991  LWLockWaitListLock(lock);
992 
993  /* setting the flag is protected by the spinlock */
995 
996  MyProc->lwWaiting = true;
997  MyProc->lwWaitMode = mode;
998 
999  /* LW_WAIT_UNTIL_FREE waiters are always at the front of the queue */
1000  if (mode == LW_WAIT_UNTIL_FREE)
1001  proclist_push_head(&lock->waiters, MyProc->pgprocno, lwWaitLink);
1002  else
1003  proclist_push_tail(&lock->waiters, MyProc->pgprocno, lwWaitLink);
1004 
1005  /* Can release the mutex now */
1006  LWLockWaitListUnlock(lock);
1007 
1008 #ifdef LOCK_DEBUG
1009  pg_atomic_fetch_add_u32(&lock->nwaiters, 1);
1010 #endif
1011 
1012 }
#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:127
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:858
uint8 lwWaitMode
Definition: proc.h:128
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 proclist_push_tail(list, procno, link_member)
Definition: proclist.h:180
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:806
int pgprocno
Definition: proc.h:110
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 598 of file lwlock.c.

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

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

599 {
600  Assert(LWLockTrancheArray != NULL);
601 
602  if (tranche_id >= LWLockTranchesAllocated)
603  {
605  int j = LWLockTranchesAllocated;
606 
607  while (i <= tranche_id)
608  i *= 2;
609 
610  LWLockTrancheArray = (char **)
611  repalloc(LWLockTrancheArray, i * sizeof(char *));
613  while (j < LWLockTranchesAllocated)
614  LWLockTrancheArray[j++] = NULL;
615  }
616 
617  LWLockTrancheArray[tranche_id] = tranche_name;
618 }
static int LWLockTranchesAllocated
Definition: lwlock.c:115
static char ** LWLockTrancheArray
Definition: lwlock.c:114
#define Assert(condition)
Definition: c.h:681
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:962
int i
void LWLockRelease ( LWLock lock)

Definition at line 1721 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(), apw_detach_shmem(), apw_dump_now(), apw_init_shmem(), apw_load_buffers(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AsyncShmemInit(), AtAbort_Twophase(), AtPrepare_PredicateLocks(), attach_internal(), autoprewarm_main(), autoprewarm_start_worker(), 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(), DropSubscription(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), 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(), 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(), FinishPreparedTransaction(), FlushDatabaseBuffers(), FlushRelationBuffers(), ForceTransactionIdLimitUpdate(), ForwardFsyncRequest(), FreeWorkerInfo(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), 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_get_replication_slots(), 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(), 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(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquire(), ReplicationSlotCleanup(), 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(), resize(), RestoreScratchTarget(), restoreTwoPhaseData(), 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(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdGetStatus(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdLimitedForOldSnapshots(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), txid_status(), UpdateMinRecoveryPoint(), vacuum_rel(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_relation_state_change(), wait_for_worker_state_change(), WaitForReplicationWorkerAttach(), WaitIO(), WaitOnLock(), write_relcache_init_file(), xact_redo(), xact_redo_abort(), xact_redo_commit(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), XLogFlush(), and XLogNeedsFlush().

1722 {
1723  LWLockMode mode;
1724  uint32 oldstate;
1725  bool check_waiters;
1726  int i;
1727 
1728  /*
1729  * Remove lock from list of locks held. Usually, but not always, it will
1730  * be the latest-acquired lock; so search array backwards.
1731  */
1732  for (i = num_held_lwlocks; --i >= 0;)
1733  if (lock == held_lwlocks[i].lock)
1734  break;
1735 
1736  if (i < 0)
1737  elog(ERROR, "lock %s is not held", T_NAME(lock));
1738 
1739  mode = held_lwlocks[i].mode;
1740 
1741  num_held_lwlocks--;
1742  for (; i < num_held_lwlocks; i++)
1743  held_lwlocks[i] = held_lwlocks[i + 1];
1744 
1745  PRINT_LWDEBUG("LWLockRelease", lock, mode);
1746 
1747  /*
1748  * Release my hold on lock, after that it can immediately be acquired by
1749  * others, even if we still have to wakeup other waiters.
1750  */
1751  if (mode == LW_EXCLUSIVE)
1752  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_EXCLUSIVE);
1753  else
1754  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_SHARED);
1755 
1756  /* nobody else can have that kind of lock */
1757  Assert(!(oldstate & LW_VAL_EXCLUSIVE));
1758 
1759 
1760  /*
1761  * We're still waiting for backends to get scheduled, don't wake them up
1762  * again.
1763  */
1764  if ((oldstate & (LW_FLAG_HAS_WAITERS | LW_FLAG_RELEASE_OK)) ==
1766  (oldstate & LW_LOCK_MASK) == 0)
1767  check_waiters = true;
1768  else
1769  check_waiters = false;
1770 
1771  /*
1772  * As waking up waiters requires the spinlock to be acquired, only do so
1773  * if necessary.
1774  */
1775  if (check_waiters)
1776  {
1777  /* XXX: remove before commit? */
1778  LOG_LWDEBUG("LWLockRelease", lock, "releasing waiters");
1779  LWLockWakeup(lock);
1780  }
1781 
1782  TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
1783 
1784  /*
1785  * Now okay to allow cancel/die interrupts.
1786  */
1788 }
#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:117
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:871
unsigned int uint32
Definition: c.h:258
static int num_held_lwlocks
Definition: lwlock.c:142
#define Assert(condition)
Definition: c.h:681
#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 1820 of file lwlock.c.

References HOLD_INTERRUPTS, LWLockRelease(), and num_held_lwlocks.

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

1821 {
1822  while (num_held_lwlocks > 0)
1823  {
1824  HOLD_INTERRUPTS(); /* match the upcoming RESUME_INTERRUPTS */
1825 
1827  }
1828 }
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1721
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:115
void LWLockReleaseClearVar ( LWLock lock,
uint64 *  valptr,
uint64  val 
)

Definition at line 1794 of file lwlock.c.

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

Referenced by WALInsertLockRelease().

1795 {
1796  LWLockWaitListLock(lock);
1797 
1798  /*
1799  * Set the variable's value before releasing the lock, that prevents race
1800  * a race condition wherein a new locker acquires the lock, but hasn't yet
1801  * set the variables value.
1802  */
1803  *valptr = val;
1804  LWLockWaitListUnlock(lock);
1805 
1806  LWLockRelease(lock);
1807 }
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:858
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1721
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:806
long val
Definition: informix.c:689
static void LWLockReportWaitEnd ( void  )
inlinestatic

Definition at line 700 of file lwlock.c.

References pgstat_report_wait_end().

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

701 {
703 }
static void pgstat_report_wait_end(void)
Definition: pgstat.h:1244
static void LWLockReportWaitStart ( LWLock lock)
inlinestatic

Definition at line 691 of file lwlock.c.

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

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

692 {
694 }
uint16 tranche
Definition: lwlock.h:34
static void pgstat_report_wait_start(uint32 wait_event_info)
Definition: pgstat.h:1220
#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:350
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 1667 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().

1668 {
1669  proclist_head wakeup;
1670  proclist_mutable_iter iter;
1671 
1672  PRINT_LWDEBUG("LWLockUpdateVar", lock, LW_EXCLUSIVE);
1673 
1674  proclist_init(&wakeup);
1675 
1676  LWLockWaitListLock(lock);
1677 
1679 
1680  /* Update the lock's value */
1681  *valptr = val;
1682 
1683  /*
1684  * See if there are any LW_WAIT_UNTIL_FREE waiters that need to be woken
1685  * up. They are always in the front of the queue.
1686  */
1687  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
1688  {
1689  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1690 
1691  if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
1692  break;
1693 
1694  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
1695  proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
1696  }
1697 
1698  /* We are done updating shared state of the lock itself. */
1699  LWLockWaitListUnlock(lock);
1700 
1701  /*
1702  * Awaken any waiters I removed from the queue.
1703  */
1704  proclist_foreach_modify(iter, &wakeup, lwWaitLink)
1705  {
1706  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1707 
1708  proclist_delete(&wakeup, iter.cur, lwWaitLink);
1709  /* check comment in LWLockWakeup() about this barrier */
1710  pg_write_barrier();
1711  waiter->lwWaiting = false;
1712  PGSemaphoreUnlock(waiter->sem);
1713  }
1714 }
#define GetPGProcByNumber(n)
Definition: proc.h:277
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:323
proclist_head waiters
Definition: lwlock.h:36
bool lwWaiting
Definition: proc.h:127
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:858
#define proclist_foreach_modify(iter, lhead, link_member)
Definition: proclist.h:195
uint8 lwWaitMode
Definition: proc.h:128
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:681
#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:806
#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:101
Definition: proc.h:95
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 1528 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, RESUME_INTERRUPTS, PGPROC::sem, LWLock::state, and T_NAME.

Referenced by WaitXLogInsertionsToFinish().

1529 {
1530  PGPROC *proc = MyProc;
1531  int extraWaits = 0;
1532  bool result = false;
1533 #ifdef LWLOCK_STATS
1534  lwlock_stats *lwstats;
1535 
1536  lwstats = get_lwlock_stats_entry(lock);
1537 #endif
1538 
1539  PRINT_LWDEBUG("LWLockWaitForVar", lock, LW_WAIT_UNTIL_FREE);
1540 
1541  /*
1542  * Lock out cancel/die interrupts while we sleep on the lock. There is no
1543  * cleanup mechanism to remove us from the wait queue if we got
1544  * interrupted.
1545  */
1546  HOLD_INTERRUPTS();
1547 
1548  /*
1549  * Loop here to check the lock's status after each time we are signaled.
1550  */
1551  for (;;)
1552  {
1553  bool mustwait;
1554 
1555  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1556  &result);
1557 
1558  if (!mustwait)
1559  break; /* the lock was free or value didn't match */
1560 
1561  /*
1562  * Add myself to wait queue. Note that this is racy, somebody else
1563  * could wakeup before we're finished queuing. NB: We're using nearly
1564  * the same twice-in-a-row lock acquisition protocol as
1565  * LWLockAcquire(). Check its comments for details. The only
1566  * difference is that we also have to check the variable's values when
1567  * checking the state of the lock.
1568  */
1570 
1571  /*
1572  * Set RELEASE_OK flag, to make sure we get woken up as soon as the
1573  * lock is released.
1574  */
1576 
1577  /*
1578  * We're now guaranteed to be woken up if necessary. Recheck the lock
1579  * and variables state.
1580  */
1581  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1582  &result);
1583 
1584  /* Ok, no conflict after we queued ourselves. Undo queueing. */
1585  if (!mustwait)
1586  {
1587  LOG_LWDEBUG("LWLockWaitForVar", lock, "free, undoing queue");
1588 
1589  LWLockDequeueSelf(lock);
1590  break;
1591  }
1592 
1593  /*
1594  * Wait until awakened.
1595  *
1596  * Since we share the process wait semaphore with the regular lock
1597  * manager and ProcWaitForSignal, and we may need to acquire an LWLock
1598  * while one of those is pending, it is possible that we get awakened
1599  * for a reason other than being signaled by LWLockRelease. If so,
1600  * loop back and wait again. Once we've gotten the LWLock,
1601  * re-increment the sema by the number of additional signals received,
1602  * so that the lock manager or signal manager will see the received
1603  * signal when it next waits.
1604  */
1605  LOG_LWDEBUG("LWLockWaitForVar", lock, "waiting");
1606 
1607 #ifdef LWLOCK_STATS
1608  lwstats->block_count++;
1609 #endif
1610 
1611  LWLockReportWaitStart(lock);
1612  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE);
1613 
1614  for (;;)
1615  {
1616  PGSemaphoreLock(proc->sem);
1617  if (!proc->lwWaiting)
1618  break;
1619  extraWaits++;
1620  }
1621 
1622 #ifdef LOCK_DEBUG
1623  {
1624  /* not waiting anymore */
1625  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1626 
1627  Assert(nwaiters < MAX_BACKENDS);
1628  }
1629 #endif
1630 
1631  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE);
1633 
1634  LOG_LWDEBUG("LWLockWaitForVar", lock, "awakened");
1635 
1636  /* Now loop back and check the status of the lock again. */
1637  }
1638 
1639  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), LW_EXCLUSIVE);
1640 
1641  /*
1642  * Fix the process wait semaphore's count for any absorbed wakeups.
1643  */
1644  while (extraWaits-- > 0)
1645  PGSemaphoreUnlock(proc->sem);
1646 
1647  /*
1648  * Now okay to allow cancel/die interrupts.
1649  */
1651 
1652  return result;
1653 }
#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:127
pg_atomic_uint32 state
Definition: lwlock.h:35
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:117
#define MAX_BACKENDS
Definition: postmaster.h:75
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:700
unsigned int uint32
Definition: c.h:258
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1022
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:691
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:978
#define Assert(condition)
Definition: c.h:681
#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:1468
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:115
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:383
PGSemaphore sem
Definition: proc.h:101
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:996
Definition: proc.h:95
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:228
static void LWLockWaitListLock ( LWLock lock)
static

Definition at line 806 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().

807 {
808  uint32 old_state;
809 #ifdef LWLOCK_STATS
810  lwlock_stats *lwstats;
811  uint32 delays = 0;
812 
813  lwstats = get_lwlock_stats_entry(lock);
814 #endif
815 
816  while (true)
817  {
818  /* always try once to acquire lock directly */
819  old_state = pg_atomic_fetch_or_u32(&lock->state, LW_FLAG_LOCKED);
820  if (!(old_state & LW_FLAG_LOCKED))
821  break; /* got lock */
822 
823  /* and then spin without atomic operations until lock is released */
824  {
825  SpinDelayStatus delayStatus;
826 
827  init_local_spin_delay(&delayStatus);
828 
829  while (old_state & LW_FLAG_LOCKED)
830  {
831  perform_spin_delay(&delayStatus);
832  old_state = pg_atomic_read_u32(&lock->state);
833  }
834 #ifdef LWLOCK_STATS
835  delays += delayStatus.delays;
836 #endif
837  finish_spin_delay(&delayStatus);
838  }
839 
840  /*
841  * Retry. The lock might obviously already be re-acquired by the time
842  * we're attempting to get it again.
843  */
844  }
845 
846 #ifdef LWLOCK_STATS
847  lwstats->spin_delay_count += delays;
848 #endif
849 }
#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:258
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 858 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().

859 {
861 
862  old_state = pg_atomic_fetch_and_u32(&lock->state, ~LW_FLAG_LOCKED);
863 
864  Assert(old_state & LW_FLAG_LOCKED);
865 }
#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:258
#define Assert(condition)
Definition: c.h:681
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:996
static void LWLockWakeup ( LWLock lock)
static

Definition at line 871 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().

872 {
873  bool new_release_ok;
874  bool wokeup_somebody = false;
875  proclist_head wakeup;
877 
878  proclist_init(&wakeup);
879 
880  new_release_ok = true;
881 
882  /* lock wait list while collecting backends to wake up */
883  LWLockWaitListLock(lock);
884 
885  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
886  {
887  PGPROC *waiter = GetPGProcByNumber(iter.cur);
888 
889  if (wokeup_somebody && waiter->lwWaitMode == LW_EXCLUSIVE)
890  continue;
891 
892  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
893  proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
894 
895  if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
896  {
897  /*
898  * Prevent additional wakeups until retryer gets to run. Backends
899  * that are just waiting for the lock to become free don't retry
900  * automatically.
901  */
902  new_release_ok = false;
903 
904  /*
905  * Don't wakeup (further) exclusive locks.
906  */
907  wokeup_somebody = true;
908  }
909 
910  /*
911  * Once we've woken up an exclusive lock, there's no point in waking
912  * up anybody else.
913  */
914  if (waiter->lwWaitMode == LW_EXCLUSIVE)
915  break;
916  }
917 
919 
920  /* unset required flags, and release lock, in one fell swoop */
921  {
922  uint32 old_state;
923  uint32 desired_state;
924 
925  old_state = pg_atomic_read_u32(&lock->state);
926  while (true)
927  {
928  desired_state = old_state;
929 
930  /* compute desired flags */
931 
932  if (new_release_ok)
933  desired_state |= LW_FLAG_RELEASE_OK;
934  else
935  desired_state &= ~LW_FLAG_RELEASE_OK;
936 
937  if (proclist_is_empty(&wakeup))
938  desired_state &= ~LW_FLAG_HAS_WAITERS;
939 
940  desired_state &= ~LW_FLAG_LOCKED; /* release lock */
941 
942  if (pg_atomic_compare_exchange_u32(&lock->state, &old_state,
943  desired_state))
944  break;
945  }
946  }
947 
948  /* Awaken any waiters I removed from the queue. */
949  proclist_foreach_modify(iter, &wakeup, lwWaitLink)
950  {
951  PGPROC *waiter = GetPGProcByNumber(iter.cur);
952 
953  LOG_LWDEBUG("LWLockRelease", lock, "release waiter");
954  proclist_delete(&wakeup, iter.cur, lwWaitLink);
955 
956  /*
957  * Guarantee that lwWaiting being unset only becomes visible once the
958  * unlink from the link has completed. Otherwise the target backend
959  * could be woken up for other reason and enqueue for a new lock - if
960  * that happens before the list unlink happens, the list would end up
961  * being corrupted.
962  *
963  * The barrier pairs with the LWLockWaitListLock() when enqueuing for
964  * another lock.
965  */
967  waiter->lwWaiting = false;
968  PGSemaphoreUnlock(waiter->sem);
969  }
970 }
#define GetPGProcByNumber(n)
Definition: proc.h:277
#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:127
#define proclist_foreach_modify(iter, lhead, link_member)
Definition: proclist.h:195
uint8 lwWaitMode
Definition: proc.h:128
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:258
#define Assert(condition)
Definition: c.h:681
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:806
static void proclist_init(proclist_head *list)
Definition: proclist.h:29
#define pg_write_barrier()
Definition: atomics.h:162
PGSemaphore sem
Definition: proc.h:101
Definition: proc.h:95
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_SESSION_DSA, LWTRANCHE_SESSION_RECORD_TABLE, LWTRANCHE_SESSION_TYPMOD_TABLE, LWTRANCHE_TBM, MainLWLockNames, MemoryContextAllocZero(), NamedLWLockTrancheRequests, 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  "session_dsa");
516  "session_record_table");
518  "session_typmod_table");
520 
521  /* Register named tranches. */
522  for (i = 0; i < NamedLWLockTrancheRequests; i++)
524  NamedLWLockTrancheArray[i].trancheName);
525 }
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:741
static char ** LWLockTrancheArray
Definition: lwlock.c:114
#define Assert(condition)
Definition: c.h:681
void LWLockRegisterTranche(int tranche_id, char *tranche_name)
Definition: lwlock.c:598
char * MainLWLockNames[]
int i
void RequestNamedLWLockTranche ( const char *  tranche_name,
int  num_lwlocks 
)

Definition at line 633 of file lwlock.c.

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

Referenced by _PG_init().

634 {
635  NamedLWLockTrancheRequest *request;
636 
638  return; /* too late */
639 
640  if (NamedLWLockTrancheRequestArray == NULL)
641  {
646  * sizeof(NamedLWLockTrancheRequest));
647  }
648 
650  {
652 
653  while (i <= NamedLWLockTrancheRequests)
654  i *= 2;
655 
658  i * sizeof(NamedLWLockTrancheRequest));
660  }
661 
663  Assert(strlen(tranche_name) + 1 < NAMEDATALEN);
664  StrNCpy(request->tranche_name, tranche_name, NAMEDATALEN);
665  request->num_lwlocks = num_lwlocks;
667 }
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:101
MemoryContext TopMemoryContext
Definition: mcxt.c:43
static int NamedLWLockTrancheRequestsAllocated
Definition: lwlock.c:153
#define Assert(condition)
Definition: c.h:681
#define StrNCpy(dst, src, len)
Definition: c.h:836
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:962
NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:152
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:706
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().