PostgreSQL Source Code  git master
lwlock.h File Reference
#include "port/atomics.h"
#include "storage/proclist_types.h"
#include "storage/lwlocknames.h"
Include dependency graph for lwlock.h:
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Data Structures

struct  LWLock
 
union  LWLockPadded
 
union  LWLockMinimallyPadded
 
struct  NamedLWLockTranche
 

Macros

#define LWLOCK_PADDED_SIZE   PG_CACHE_LINE_SIZE
 
#define LWLOCK_MINIMAL_SIZE   (sizeof(LWLock) <= 32 ? 32 : 64)
 
#define NUM_BUFFER_PARTITIONS   128
 
#define LOG2_NUM_LOCK_PARTITIONS   4
 
#define NUM_LOCK_PARTITIONS   (1 << LOG2_NUM_LOCK_PARTITIONS)
 
#define LOG2_NUM_PREDICATELOCK_PARTITIONS   4
 
#define NUM_PREDICATELOCK_PARTITIONS   (1 << LOG2_NUM_PREDICATELOCK_PARTITIONS)
 
#define BUFFER_MAPPING_LWLOCK_OFFSET   NUM_INDIVIDUAL_LWLOCKS
 
#define LOCK_MANAGER_LWLOCK_OFFSET   (BUFFER_MAPPING_LWLOCK_OFFSET + NUM_BUFFER_PARTITIONS)
 
#define PREDICATELOCK_MANAGER_LWLOCK_OFFSET   (LOCK_MANAGER_LWLOCK_OFFSET + NUM_LOCK_PARTITIONS)
 
#define NUM_FIXED_LWLOCKS   (PREDICATELOCK_MANAGER_LWLOCK_OFFSET + NUM_PREDICATELOCK_PARTITIONS)
 

Typedefs

typedef struct LWLock LWLock
 
typedef union LWLockPadded LWLockPadded
 
typedef union LWLockMinimallyPadded LWLockMinimallyPadded
 
typedef struct NamedLWLockTranche NamedLWLockTranche
 
typedef enum LWLockMode LWLockMode
 
typedef enum BuiltinTrancheIds BuiltinTrancheIds
 
typedef LWLockLWLockId
 

Enumerations

enum  LWLockMode { LW_EXCLUSIVE, LW_SHARED, LW_WAIT_UNTIL_FREE }
 
enum  BuiltinTrancheIds {
  LWTRANCHE_XACT_BUFFER = NUM_INDIVIDUAL_LWLOCKS, LWTRANCHE_COMMITTS_BUFFER, LWTRANCHE_SUBTRANS_BUFFER, LWTRANCHE_MULTIXACTOFFSET_BUFFER,
  LWTRANCHE_MULTIXACTMEMBER_BUFFER, LWTRANCHE_NOTIFY_BUFFER, LWTRANCHE_SERIAL_BUFFER, LWTRANCHE_WAL_INSERT,
  LWTRANCHE_BUFFER_CONTENT, LWTRANCHE_BUFFER_IO, LWTRANCHE_REPLICATION_ORIGIN_STATE, LWTRANCHE_REPLICATION_SLOT_IO,
  LWTRANCHE_LOCK_FASTPATH, LWTRANCHE_BUFFER_MAPPING, LWTRANCHE_LOCK_MANAGER, LWTRANCHE_PREDICATE_LOCK_MANAGER,
  LWTRANCHE_PARALLEL_HASH_JOIN, LWTRANCHE_PARALLEL_QUERY_DSA, LWTRANCHE_PER_SESSION_DSA, LWTRANCHE_PER_SESSION_RECORD_TYPE,
  LWTRANCHE_PER_SESSION_RECORD_TYPMOD, LWTRANCHE_SHARED_TUPLESTORE, LWTRANCHE_SHARED_TIDBITMAP, LWTRANCHE_PARALLEL_APPEND,
  LWTRANCHE_PER_XACT_PREDICATE_LIST, LWTRANCHE_FIRST_USER_DEFINED
}
 

Functions

bool LWLockAcquire (LWLock *lock, LWLockMode mode)
 
bool LWLockConditionalAcquire (LWLock *lock, LWLockMode mode)
 
bool LWLockAcquireOrWait (LWLock *lock, LWLockMode mode)
 
void LWLockRelease (LWLock *lock)
 
void LWLockReleaseClearVar (LWLock *lock, uint64 *valptr, uint64 val)
 
void LWLockReleaseAll (void)
 
bool LWLockHeldByMe (LWLock *lock)
 
bool LWLockHeldByMeInMode (LWLock *lock, LWLockMode mode)
 
bool LWLockWaitForVar (LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval)
 
void LWLockUpdateVar (LWLock *lock, uint64 *valptr, uint64 value)
 
Size LWLockShmemSize (void)
 
void CreateLWLocks (void)
 
void InitLWLockAccess (void)
 
const char * GetLWLockIdentifier (uint32 classId, uint16 eventId)
 
void RequestNamedLWLockTranche (const char *tranche_name, int num_lwlocks)
 
LWLockPaddedGetNamedLWLockTranche (const char *tranche_name)
 
int LWLockNewTrancheId (void)
 
void LWLockRegisterTranche (int tranche_id, const char *tranche_name)
 
void LWLockInitialize (LWLock *lock, int tranche_id)
 

Variables

PGDLLIMPORT LWLockPaddedMainLWLockArray
 
PGDLLIMPORT NamedLWLockTrancheNamedLWLockTrancheArray
 
PGDLLIMPORT int NamedLWLockTrancheRequests
 

Macro Definition Documentation

◆ BUFFER_MAPPING_LWLOCK_OFFSET

#define BUFFER_MAPPING_LWLOCK_OFFSET   NUM_INDIVIDUAL_LWLOCKS

Definition at line 122 of file lwlock.h.

Referenced by InitializeLWLocks().

◆ LOCK_MANAGER_LWLOCK_OFFSET

#define LOCK_MANAGER_LWLOCK_OFFSET   (BUFFER_MAPPING_LWLOCK_OFFSET + NUM_BUFFER_PARTITIONS)

Definition at line 123 of file lwlock.h.

Referenced by InitializeLWLocks().

◆ LOG2_NUM_LOCK_PARTITIONS

#define LOG2_NUM_LOCK_PARTITIONS   4

Definition at line 114 of file lwlock.h.

Referenced by proclock_hash(), and ProcLockHashCode().

◆ LOG2_NUM_PREDICATELOCK_PARTITIONS

#define LOG2_NUM_PREDICATELOCK_PARTITIONS   4

Definition at line 118 of file lwlock.h.

◆ LWLOCK_MINIMAL_SIZE

#define LWLOCK_MINIMAL_SIZE   (sizeof(LWLock) <= 32 ? 32 : 64)

Definition at line 73 of file lwlock.h.

Referenced by CreateLWLocks().

◆ LWLOCK_PADDED_SIZE

#define LWLOCK_PADDED_SIZE   PG_CACHE_LINE_SIZE

Definition at line 72 of file lwlock.h.

Referenced by CreateLWLocks(), and LWLockShmemSize().

◆ NUM_BUFFER_PARTITIONS

#define NUM_BUFFER_PARTITIONS   128

Definition at line 111 of file lwlock.h.

Referenced by InitBufTable(), InitializeLWLocks(), StrategyInitialize(), and StrategyShmemSize().

◆ NUM_FIXED_LWLOCKS

Definition at line 127 of file lwlock.h.

Referenced by GetNamedLWLockTranche(), InitializeLWLocks(), and LWLockShmemSize().

◆ NUM_LOCK_PARTITIONS

◆ NUM_PREDICATELOCK_PARTITIONS

◆ PREDICATELOCK_MANAGER_LWLOCK_OFFSET

#define PREDICATELOCK_MANAGER_LWLOCK_OFFSET   (LOCK_MANAGER_LWLOCK_OFFSET + NUM_LOCK_PARTITIONS)

Definition at line 125 of file lwlock.h.

Referenced by InitializeLWLocks().

Typedef Documentation

◆ BuiltinTrancheIds

◆ LWLock

typedef struct LWLock LWLock

◆ LWLockId

typedef LWLock* LWLockId

Definition at line 229 of file lwlock.h.

◆ LWLockMinimallyPadded

◆ LWLockMode

typedef enum LWLockMode LWLockMode

◆ LWLockPadded

typedef union LWLockPadded LWLockPadded

◆ NamedLWLockTranche

Enumeration Type Documentation

◆ BuiltinTrancheIds

Enumerator
LWTRANCHE_XACT_BUFFER 
LWTRANCHE_COMMITTS_BUFFER 
LWTRANCHE_SUBTRANS_BUFFER 
LWTRANCHE_MULTIXACTOFFSET_BUFFER 
LWTRANCHE_MULTIXACTMEMBER_BUFFER 
LWTRANCHE_NOTIFY_BUFFER 
LWTRANCHE_SERIAL_BUFFER 
LWTRANCHE_WAL_INSERT 
LWTRANCHE_BUFFER_CONTENT 
LWTRANCHE_BUFFER_IO 
LWTRANCHE_REPLICATION_ORIGIN_STATE 
LWTRANCHE_REPLICATION_SLOT_IO 
LWTRANCHE_LOCK_FASTPATH 
LWTRANCHE_BUFFER_MAPPING 
LWTRANCHE_LOCK_MANAGER 
LWTRANCHE_PREDICATE_LOCK_MANAGER 
LWTRANCHE_PARALLEL_HASH_JOIN 
LWTRANCHE_PARALLEL_QUERY_DSA 
LWTRANCHE_PER_SESSION_DSA 
LWTRANCHE_PER_SESSION_RECORD_TYPE 
LWTRANCHE_PER_SESSION_RECORD_TYPMOD 
LWTRANCHE_SHARED_TUPLESTORE 
LWTRANCHE_SHARED_TIDBITMAP 
LWTRANCHE_PARALLEL_APPEND 
LWTRANCHE_PER_XACT_PREDICATE_LIST 
LWTRANCHE_FIRST_USER_DEFINED 

Definition at line 194 of file lwlock.h.

195 {
196  LWTRANCHE_XACT_BUFFER = NUM_INDIVIDUAL_LWLOCKS,
BuiltinTrancheIds
Definition: lwlock.h:194

◆ LWLockMode

enum LWLockMode
Enumerator
LW_EXCLUSIVE 
LW_SHARED 
LW_WAIT_UNTIL_FREE 

Definition at line 130 of file lwlock.h.

131 {
132  LW_EXCLUSIVE,
133  LW_SHARED,
134  LW_WAIT_UNTIL_FREE /* A special mode used in PGPROC->lwWaitMode,
135  * when waiting for lock to become free. Not
136  * to be used as LWLockAcquire argument */
137 } LWLockMode;
LWLockMode
Definition: lwlock.h:130

Function Documentation

◆ CreateLWLocks()

void CreateLWLocks ( void  )

Definition at line 467 of file lwlock.c.

References i, InitializeLWLocks(), IsUnderPostmaster, LW_VAL_EXCLUSIVE, LWLOCK_MINIMAL_SIZE, LWLOCK_PADDED_SIZE, LWLockRegisterTranche(), LWLockShmemSize(), LWTRANCHE_FIRST_USER_DEFINED, MAX_BACKENDS, NamedLWLockTrancheRequests, ShmemAlloc(), and StaticAssertStmt.

Referenced by CreateSharedMemoryAndSemaphores().

468 {
470  "MAX_BACKENDS too big for lwlock.c");
471 
473  sizeof(LWLock) <= LWLOCK_PADDED_SIZE,
474  "Miscalculated LWLock padding");
475 
476  if (!IsUnderPostmaster)
477  {
478  Size spaceLocks = LWLockShmemSize();
479  int *LWLockCounter;
480  char *ptr;
481 
482  /* Allocate space */
483  ptr = (char *) ShmemAlloc(spaceLocks);
484 
485  /* Leave room for dynamic allocation of tranches */
486  ptr += sizeof(int);
487 
488  /* Ensure desired alignment of LWLock array */
489  ptr += LWLOCK_PADDED_SIZE - ((uintptr_t) ptr) % LWLOCK_PADDED_SIZE;
490 
491  MainLWLockArray = (LWLockPadded *) ptr;
492 
493  /*
494  * Initialize the dynamic-allocation counter for tranches, which is
495  * stored just before the first LWLock.
496  */
497  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
498  *LWLockCounter = LWTRANCHE_FIRST_USER_DEFINED;
499 
500  /* Initialize all LWLocks */
502  }
503 
504  /* Register named extension LWLock tranches in the current process. */
505  for (int i = 0; i < NamedLWLockTrancheRequests; i++)
507  NamedLWLockTrancheArray[i].trancheName);
508 }
Definition: lwlock.h:31
void * ShmemAlloc(Size size)
Definition: shmem.c:161
NamedLWLockTranche * NamedLWLockTrancheArray
Definition: lwlock.c:239
Size LWLockShmemSize(void)
Definition: lwlock.c:434
void LWLockRegisterTranche(int tranche_id, const char *tranche_name)
Definition: lwlock.c:651
#define StaticAssertStmt(condition, errmessage)
Definition: c.h:906
#define LWLOCK_MINIMAL_SIZE
Definition: lwlock.h:73
#define MAX_BACKENDS
Definition: postmaster.h:75
int NamedLWLockTrancheRequests
Definition: lwlock.c:236
bool IsUnderPostmaster
Definition: globals.c:110
unsigned int uint32
Definition: c.h:429
static void InitializeLWLocks(void)
Definition: lwlock.c:514
size_t Size
Definition: c.h:528
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
int i
#define LWLOCK_PADDED_SIZE
Definition: lwlock.h:72
LWLockPadded * MainLWLockArray
Definition: lwlock.c:200

◆ GetLWLockIdentifier()

const char* GetLWLockIdentifier ( uint32  classId,
uint16  eventId 
)

Definition at line 807 of file lwlock.c.

References Assert, GetLWTrancheName(), and PG_WAIT_LWLOCK.

Referenced by pgstat_get_wait_event().

808 {
809  Assert(classId == PG_WAIT_LWLOCK);
810  /* The event IDs are just tranche numbers. */
811  return GetLWTrancheName(eventId);
812 }
static const char * GetLWTrancheName(uint16 trancheId)
Definition: lwlock.c:779
#define Assert(condition)
Definition: c.h:792
#define PG_WAIT_LWLOCK
Definition: pgstat.h:895

◆ GetNamedLWLockTranche()

LWLockPadded* GetNamedLWLockTranche ( const char *  tranche_name)

Definition at line 597 of file lwlock.c.

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

Referenced by pgss_shmem_startup().

598 {
599  int lock_pos;
600  int i;
601 
602  /*
603  * Obtain the position of base address of LWLock belonging to requested
604  * tranche_name in MainLWLockArray. LWLocks for named tranches are placed
605  * in MainLWLockArray after fixed locks.
606  */
607  lock_pos = NUM_FIXED_LWLOCKS;
608  for (i = 0; i < NamedLWLockTrancheRequests; i++)
609  {
610  if (strcmp(NamedLWLockTrancheRequestArray[i].tranche_name,
611  tranche_name) == 0)
612  return &MainLWLockArray[lock_pos];
613 
615  }
616 
617  elog(ERROR, "requested tranche is not registered");
618 
619  /* just to keep compiler quiet */
620  return NULL;
621 }
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:127
#define ERROR
Definition: elog.h:45
int NamedLWLockTrancheRequests
Definition: lwlock.c:236
static NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:227
#define elog(elevel,...)
Definition: elog.h:228
int i
LWLockPadded * MainLWLockArray
Definition: lwlock.c:200

◆ InitLWLockAccess()

void InitLWLockAccess ( void  )

Definition at line 581 of file lwlock.c.

Referenced by InitProcess().

582 {
583 #ifdef LWLOCK_STATS
584  init_lwlock_stats();
585 #endif
586 }

◆ LWLockAcquire()

bool LWLockAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1206 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(), AbsorbSyncRequests(), ActivateCommitTs(), AdvanceNextFullTransactionIdPastXid(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_init_shmem(), apw_load_buffers(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), 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(), check_for_freed_segments(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckRecoveryConsistency(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), choose_next_subplan_for_leader(), choose_next_subplan_for_worker(), CleanupInvalidationState(), ClearOldPredicateLocks(), clog_redo(), commit_ts_redo(), ComputeXidHorizons(), copy_replication_slot(), 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(), ExecParallelHashMergeCounters(), ExecParallelHashPopChunkQueue(), ExecParallelHashTupleAlloc(), ExecParallelHashTuplePrealloc(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), FindAndDropRelFileNodeBuffers(), FinishPreparedTransaction(), FlushDatabaseBuffers(), FlushRelationBuffers(), FlushRelationsAllBuffers(), ForceTransactionIdLimitUpdate(), ForwardSyncRequest(), FreeWorkerInfo(), get_xid_status(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldSnapshotFromTimeMapping(), GetOldSnapshotTimeMapping(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionData(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetVirtualXIDsDelayingChkpt(), HandleAutoVacLauncherInterrupts(), HaveVirtualXIDsDelayingChkpt(), InstallXLogFileSegment(), InvalidateBuffer(), InvalidateObsoleteReplicationSlots(), 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(), PageIsPredicateLocked(), perform_relmap_update(), pg_get_replication_slots(), pg_get_shmem_allocations(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_statements_internal(), pg_xact_status(), pgss_shmem_startup(), pgss_store(), pgstat_reset_replslot_counter(), PostPrepare_Locks(), PostPrepare_MultiXact(), PostPrepare_Twophase(), PreCommit_CheckForSerializationFailure(), PreCommit_Notify(), predicatelock_twophase_recover(), PredicateLockPageSplit(), PredicateLockTwoPhaseFinish(), PrefetchSharedBuffer(), PrescanPreparedTransactions(), ProcArrayAdd(), ProcArrayApplyRecoveryInfo(), ProcArrayApplyXidAssignment(), ProcArrayClearTransaction(), ProcArrayEndTransaction(), ProcArrayGetReplicationSlotXmin(), ProcArrayGroupClearXid(), ProcArrayInstallImportedXmin(), ProcArrayInstallRestoredXmin(), ProcArrayRemove(), ProcArraySetReplicationSlotXmin(), process_syncing_tables_for_apply(), ProcKill(), ProcSleep(), ReadBuffer_common(), ReadMultiXactCounts(), ReadMultiXactIdRange(), ReadNextFullTransactionId(), ReadNextMultiXactId(), ReadRecord(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePreInvalidate(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquireInternal(), 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(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), SerialSetActiveSerXmin(), set_indexsafe_procflags(), SetCommitTsLimit(), SetMultiXactIdLimit(), SetOffsetVacuumLimit(), SetTransactionIdLimit(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SignalVirtualTransaction(), SIInsertDataEntries(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SimpleLruWriteAll(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), StandbyRecoverPreparedTransactions(), StartBufferIO(), StartupCLOG(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), sts_parallel_scan_next(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SyncOneBuffer(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateOtherDBBackends(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), update_cached_xid_range(), UpdateMinRecoveryPoint(), vac_truncate_clog(), 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(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), and XLogReportParameters().

1207 {
1208  PGPROC *proc = MyProc;
1209  bool result = true;
1210  int extraWaits = 0;
1211 #ifdef LWLOCK_STATS
1212  lwlock_stats *lwstats;
1213 
1214  lwstats = get_lwlock_stats_entry(lock);
1215 #endif
1216 
1218 
1219  PRINT_LWDEBUG("LWLockAcquire", lock, mode);
1220 
1221 #ifdef LWLOCK_STATS
1222  /* Count lock acquisition attempts */
1223  if (mode == LW_EXCLUSIVE)
1224  lwstats->ex_acquire_count++;
1225  else
1226  lwstats->sh_acquire_count++;
1227 #endif /* LWLOCK_STATS */
1228 
1229  /*
1230  * We can't wait if we haven't got a PGPROC. This should only occur
1231  * during bootstrap or shared memory initialization. Put an Assert here
1232  * to catch unsafe coding practices.
1233  */
1234  Assert(!(proc == NULL && IsUnderPostmaster));
1235 
1236  /* Ensure we will have room to remember the lock */
1238  elog(ERROR, "too many LWLocks taken");
1239 
1240  /*
1241  * Lock out cancel/die interrupts until we exit the code section protected
1242  * by the LWLock. This ensures that interrupts will not interfere with
1243  * manipulations of data structures in shared memory.
1244  */
1245  HOLD_INTERRUPTS();
1246 
1247  /*
1248  * Loop here to try to acquire lock after each time we are signaled by
1249  * LWLockRelease.
1250  *
1251  * NOTE: it might seem better to have LWLockRelease actually grant us the
1252  * lock, rather than retrying and possibly having to go back to sleep. But
1253  * in practice that is no good because it means a process swap for every
1254  * lock acquisition when two or more processes are contending for the same
1255  * lock. Since LWLocks are normally used to protect not-very-long
1256  * sections of computation, a process needs to be able to acquire and
1257  * release the same lock many times during a single CPU time slice, even
1258  * in the presence of contention. The efficiency of being able to do that
1259  * outweighs the inefficiency of sometimes wasting a process dispatch
1260  * cycle because the lock is not free when a released waiter finally gets
1261  * to run. See pgsql-hackers archives for 29-Dec-01.
1262  */
1263  for (;;)
1264  {
1265  bool mustwait;
1266 
1267  /*
1268  * Try to grab the lock the first time, we're not in the waitqueue
1269  * yet/anymore.
1270  */
1271  mustwait = LWLockAttemptLock(lock, mode);
1272 
1273  if (!mustwait)
1274  {
1275  LOG_LWDEBUG("LWLockAcquire", lock, "immediately acquired lock");
1276  break; /* got the lock */
1277  }
1278 
1279  /*
1280  * Ok, at this point we couldn't grab the lock on the first try. We
1281  * cannot simply queue ourselves to the end of the list and wait to be
1282  * woken up because by now the lock could long have been released.
1283  * Instead add us to the queue and try to grab the lock again. If we
1284  * succeed we need to revert the queuing and be happy, otherwise we
1285  * recheck the lock. If we still couldn't grab it, we know that the
1286  * other locker will see our queue entries when releasing since they
1287  * existed before we checked for the lock.
1288  */
1289 
1290  /* add to the queue */
1291  LWLockQueueSelf(lock, mode);
1292 
1293  /* we're now guaranteed to be woken up if necessary */
1294  mustwait = LWLockAttemptLock(lock, mode);
1295 
1296  /* ok, grabbed the lock the second time round, need to undo queueing */
1297  if (!mustwait)
1298  {
1299  LOG_LWDEBUG("LWLockAcquire", lock, "acquired, undoing queue");
1300 
1301  LWLockDequeueSelf(lock);
1302  break;
1303  }
1304 
1305  /*
1306  * Wait until awakened.
1307  *
1308  * Since we share the process wait semaphore with the regular lock
1309  * manager and ProcWaitForSignal, and we may need to acquire an LWLock
1310  * while one of those is pending, it is possible that we get awakened
1311  * for a reason other than being signaled by LWLockRelease. If so,
1312  * loop back and wait again. Once we've gotten the LWLock,
1313  * re-increment the sema by the number of additional signals received,
1314  * so that the lock manager or signal manager will see the received
1315  * signal when it next waits.
1316  */
1317  LOG_LWDEBUG("LWLockAcquire", lock, "waiting");
1318 
1319 #ifdef LWLOCK_STATS
1320  lwstats->block_count++;
1321 #endif
1322 
1323  LWLockReportWaitStart(lock);
1324  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1325 
1326  for (;;)
1327  {
1328  PGSemaphoreLock(proc->sem);
1329  if (!proc->lwWaiting)
1330  break;
1331  extraWaits++;
1332  }
1333 
1334  /* Retrying, allow LWLockRelease to release waiters again. */
1336 
1337 #ifdef LOCK_DEBUG
1338  {
1339  /* not waiting anymore */
1340  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1341 
1342  Assert(nwaiters < MAX_BACKENDS);
1343  }
1344 #endif
1345 
1346  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1348 
1349  LOG_LWDEBUG("LWLockAcquire", lock, "awakened");
1350 
1351  /* Now loop back and try to acquire lock again. */
1352  result = false;
1353  }
1354 
1355  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode);
1356 
1357  /* Add lock to list of locks held by this backend */
1360 
1361  /*
1362  * Fix the process wait semaphore's count for any absorbed wakeups.
1363  */
1364  while (extraWaits-- > 0)
1365  PGSemaphoreUnlock(proc->sem);
1366 
1367  return result;
1368 }
#define T_NAME(lock)
Definition: lwlock.c:248
static PgChecksumMode mode
Definition: pg_checksums.c:61
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:343
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:824
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
PGPROC * MyProc
Definition: proc.c:68
bool lwWaiting
Definition: proc.h:170
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:208
pg_atomic_uint32 state
Definition: lwlock.h:34
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
#define ERROR
Definition: elog.h:45
#define MAX_BACKENDS
Definition: postmaster.h:75
LWLockMode mode
Definition: lwlock.c:214
bool IsUnderPostmaster
Definition: globals.c:110
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:770
unsigned int uint32
Definition: c.h:429
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1111
#define AssertArg(condition)
Definition: c.h:794
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:761
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1067
static int num_held_lwlocks
Definition: lwlock.c:217
#define Assert(condition)
Definition: c.h:792
LWLock * lock
Definition: lwlock.c:213
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:320
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:117
#define elog(elevel,...)
Definition: elog.h:228
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:372
PGSemaphore sem
Definition: proc.h:127
Definition: proc.h:121
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:143
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ LWLockAcquireOrWait()

bool LWLockAcquireOrWait ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1433 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().

1434 {
1435  PGPROC *proc = MyProc;
1436  bool mustwait;
1437  int extraWaits = 0;
1438 #ifdef LWLOCK_STATS
1439  lwlock_stats *lwstats;
1440 
1441  lwstats = get_lwlock_stats_entry(lock);
1442 #endif
1443 
1445 
1446  PRINT_LWDEBUG("LWLockAcquireOrWait", lock, mode);
1447 
1448  /* Ensure we will have room to remember the lock */
1450  elog(ERROR, "too many LWLocks taken");
1451 
1452  /*
1453  * Lock out cancel/die interrupts until we exit the code section protected
1454  * by the LWLock. This ensures that interrupts will not interfere with
1455  * manipulations of data structures in shared memory.
1456  */
1457  HOLD_INTERRUPTS();
1458 
1459  /*
1460  * NB: We're using nearly the same twice-in-a-row lock acquisition
1461  * protocol as LWLockAcquire(). Check its comments for details.
1462  */
1463  mustwait = LWLockAttemptLock(lock, mode);
1464 
1465  if (mustwait)
1466  {
1468 
1469  mustwait = LWLockAttemptLock(lock, mode);
1470 
1471  if (mustwait)
1472  {
1473  /*
1474  * Wait until awakened. Like in LWLockAcquire, be prepared for
1475  * bogus wakeups, because we share the semaphore with
1476  * ProcWaitForSignal.
1477  */
1478  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "waiting");
1479 
1480 #ifdef LWLOCK_STATS
1481  lwstats->block_count++;
1482 #endif
1483 
1484  LWLockReportWaitStart(lock);
1485  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1486 
1487  for (;;)
1488  {
1489  PGSemaphoreLock(proc->sem);
1490  if (!proc->lwWaiting)
1491  break;
1492  extraWaits++;
1493  }
1494 
1495 #ifdef LOCK_DEBUG
1496  {
1497  /* not waiting anymore */
1498  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1499 
1500  Assert(nwaiters < MAX_BACKENDS);
1501  }
1502 #endif
1503  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1505 
1506  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "awakened");
1507  }
1508  else
1509  {
1510  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "acquired, undoing queue");
1511 
1512  /*
1513  * Got lock in the second attempt, undo queueing. We need to treat
1514  * this as having successfully acquired the lock, otherwise we'd
1515  * not necessarily wake up people we've prevented from acquiring
1516  * the lock.
1517  */
1518  LWLockDequeueSelf(lock);
1519  }
1520  }
1521 
1522  /*
1523  * Fix the process wait semaphore's count for any absorbed wakeups.
1524  */
1525  while (extraWaits-- > 0)
1526  PGSemaphoreUnlock(proc->sem);
1527 
1528  if (mustwait)
1529  {
1530  /* Failed to get lock, so release interrupt holdoff */
1532  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "failed");
1533  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode);
1534  }
1535  else
1536  {
1537  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "succeeded");
1538  /* Add lock to list of locks held by this backend */
1541  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode);
1542  }
1543 
1544  return !mustwait;
1545 }
#define T_NAME(lock)
Definition: lwlock.c:248
static PgChecksumMode mode
Definition: pg_checksums.c:61
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:343
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:824
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
PGPROC * MyProc
Definition: proc.c:68
bool lwWaiting
Definition: proc.h:170
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:208
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:119
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
#define ERROR
Definition: elog.h:45
#define MAX_BACKENDS
Definition: postmaster.h:75
LWLockMode mode
Definition: lwlock.c:214
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:770
unsigned int uint32
Definition: c.h:429
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1111
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:761
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1067
static int num_held_lwlocks
Definition: lwlock.c:217
#define Assert(condition)
Definition: c.h:792
LWLock * lock
Definition: lwlock.c:213
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:320
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:117
#define elog(elevel,...)
Definition: elog.h:228
PGSemaphore sem
Definition: proc.h:127
Definition: proc.h:121
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:143
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ LWLockConditionalAcquire()

bool LWLockConditionalAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1378 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().

1379 {
1380  bool mustwait;
1381 
1383 
1384  PRINT_LWDEBUG("LWLockConditionalAcquire", lock, mode);
1385 
1386  /* Ensure we will have room to remember the lock */
1388  elog(ERROR, "too many LWLocks taken");
1389 
1390  /*
1391  * Lock out cancel/die interrupts until we exit the code section protected
1392  * by the LWLock. This ensures that interrupts will not interfere with
1393  * manipulations of data structures in shared memory.
1394  */
1395  HOLD_INTERRUPTS();
1396 
1397  /* Check for the lock */
1398  mustwait = LWLockAttemptLock(lock, mode);
1399 
1400  if (mustwait)
1401  {
1402  /* Failed to get lock, so release interrupt holdoff */
1404 
1405  LOG_LWDEBUG("LWLockConditionalAcquire", lock, "failed");
1406  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode);
1407  }
1408  else
1409  {
1410  /* Add lock to list of locks held by this backend */
1413  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode);
1414  }
1415  return !mustwait;
1416 }
#define T_NAME(lock)
Definition: lwlock.c:248
static PgChecksumMode mode
Definition: pg_checksums.c:61
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:824
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:208
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:119
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
#define ERROR
Definition: elog.h:45
LWLockMode mode
Definition: lwlock.c:214
#define AssertArg(condition)
Definition: c.h:794
static int num_held_lwlocks
Definition: lwlock.c:217
LWLock * lock
Definition: lwlock.c:213
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:117
#define elog(elevel,...)
Definition: elog.h:228
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ LWLockHeldByMe()

◆ LWLockHeldByMeInMode()

bool LWLockHeldByMeInMode ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1944 of file lwlock.c.

References i, and num_held_lwlocks.

Referenced by DeleteLockTarget(), dshash_delete_entry(), dshash_release_lock(), IsBufferCleanupOK(), logicalrep_worker_cleanup(), MarkAsPreparingGuts(), MarkBufferDirty(), PrepareRedoAdd(), PrepareRedoRemove(), ProcArrayEndTransactionInternal(), ProcessTwoPhaseBuffer(), RemoveGXact(), SearchNamedReplicationSlot(), SyncRepWakeQueue(), TransactionIdSetPageStatusInternal(), and TransferPredicateLocksToNewTarget().

1945 {
1946  int i;
1947 
1948  for (i = 0; i < num_held_lwlocks; i++)
1949  {
1950  if (held_lwlocks[i].lock == l && held_lwlocks[i].mode == mode)
1951  return true;
1952  }
1953  return false;
1954 }
static PgChecksumMode mode
Definition: pg_checksums.c:61
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
static int num_held_lwlocks
Definition: lwlock.c:217
int i

◆ LWLockInitialize()

void LWLockInitialize ( LWLock lock,
int  tranche_id 
)

Definition at line 743 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(), ExecAppendInitializeDSM(), ExecHashJoinInitializeDSM(), InitBufferPool(), InitializeLWLocks(), InitPredicateLocks(), InitProcGlobal(), ReplicationOriginShmemInit(), ReplicationSlotsShmemInit(), SimpleLruInit(), sts_initialize(), tbm_prepare_shared_iterate(), and XLOGShmemInit().

744 {
746 #ifdef LOCK_DEBUG
747  pg_atomic_init_u32(&lock->nwaiters, 0);
748 #endif
749  lock->tranche = tranche_id;
750  proclist_init(&lock->waiters);
751 }
proclist_head waiters
Definition: lwlock.h:35
pg_atomic_uint32 state
Definition: lwlock.h:34
uint16 tranche
Definition: lwlock.h:33
#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:223

◆ LWLockNewTrancheId()

int LWLockNewTrancheId ( void  )

Definition at line 627 of file lwlock.c.

References ShmemLock, SpinLockAcquire, and SpinLockRelease.

Referenced by apw_init_shmem(), and InitializeLWLocks().

628 {
629  int result;
630  int *LWLockCounter;
631 
632  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
634  result = (*LWLockCounter)++;
636 
637  return result;
638 }
#define SpinLockAcquire(lock)
Definition: spin.h:62
#define SpinLockRelease(lock)
Definition: spin.h:64
slock_t * ShmemLock
Definition: shmem.c:88
LWLockPadded * MainLWLockArray
Definition: lwlock.c:200

◆ LWLockRegisterTranche()

void LWLockRegisterTranche ( int  tranche_id,
const char *  tranche_name 
)

Definition at line 651 of file lwlock.c.

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

Referenced by apw_init_shmem(), and CreateLWLocks().

652 {
653  /* This should only be called for user-defined tranches. */
654  if (tranche_id < LWTRANCHE_FIRST_USER_DEFINED)
655  return;
656 
657  /* Convert to array index. */
658  tranche_id -= LWTRANCHE_FIRST_USER_DEFINED;
659 
660  /* If necessary, create or enlarge array. */
661  if (tranche_id >= LWLockTrancheNamesAllocated)
662  {
663  int newalloc;
664 
665  newalloc = Max(LWLockTrancheNamesAllocated, 8);
666  while (newalloc <= tranche_id)
667  newalloc *= 2;
668 
669  if (LWLockTrancheNames == NULL)
670  LWLockTrancheNames = (const char **)
672  newalloc * sizeof(char *));
673  else
674  {
675  LWLockTrancheNames = (const char **)
676  repalloc(LWLockTrancheNames, newalloc * sizeof(char *));
678  0,
679  (newalloc - LWLockTrancheNamesAllocated) * sizeof(char *));
680  }
681  LWLockTrancheNamesAllocated = newalloc;
682  }
683 
684  LWLockTrancheNames[tranche_id] = tranche_name;
685 }
static int LWLockTrancheNamesAllocated
Definition: lwlock.c:193
MemoryContext TopMemoryContext
Definition: mcxt.c:44
void * MemoryContextAllocZero(MemoryContext context, Size size)
Definition: mcxt.c:840
#define Max(x, y)
Definition: c.h:968
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1070
static const char ** LWLockTrancheNames
Definition: lwlock.c:192

◆ LWLockRelease()

void LWLockRelease ( LWLock lock)

Definition at line 1810 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(), AbsorbSyncRequests(), ActivateCommitTs(), AdvanceNextFullTransactionIdPastXid(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_init_shmem(), apw_load_buffers(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), 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(), check_for_freed_segments(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckRecoveryConsistency(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), choose_next_subplan_for_leader(), choose_next_subplan_for_worker(), CleanupInvalidationState(), ClearOldPredicateLocks(), clog_redo(), commit_ts_redo(), ComputeXidHorizons(), copy_replication_slot(), 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(), ExecParallelHashMergeCounters(), ExecParallelHashPopChunkQueue(), ExecParallelHashTupleAlloc(), ExecParallelHashTuplePrealloc(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), find_multixact_start(), FindAndDropRelFileNodeBuffers(), FinishPreparedTransaction(), FlushDatabaseBuffers(), FlushRelationBuffers(), FlushRelationsAllBuffers(), ForceTransactionIdLimitUpdate(), ForwardSyncRequest(), FreeWorkerInfo(), get_xid_status(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldSnapshotFromTimeMapping(), GetOldSnapshotTimeMapping(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetVirtualXIDsDelayingChkpt(), HandleAutoVacLauncherInterrupts(), HaveVirtualXIDsDelayingChkpt(), InstallXLogFileSegment(), InvalidateBuffer(), InvalidateObsoleteReplicationSlots(), 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(), OnConflict_CheckForSerializationFailure(), PageIsPredicateLocked(), perform_relmap_update(), pg_get_replication_slots(), pg_get_shmem_allocations(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_statements_internal(), pg_xact_status(), pgss_shmem_startup(), pgss_store(), pgstat_reset_replslot_counter(), PostPrepare_Locks(), PostPrepare_MultiXact(), PostPrepare_Twophase(), PreCommit_CheckForSerializationFailure(), PreCommit_Notify(), predicatelock_twophase_recover(), PredicateLockPageSplit(), PredicateLockTwoPhaseFinish(), PrefetchSharedBuffer(), PrescanPreparedTransactions(), ProcArrayAdd(), ProcArrayApplyRecoveryInfo(), ProcArrayApplyXidAssignment(), ProcArrayClearTransaction(), ProcArrayEndTransaction(), ProcArrayGetReplicationSlotXmin(), ProcArrayGroupClearXid(), ProcArrayInstallImportedXmin(), ProcArrayInstallRestoredXmin(), ProcArrayRemove(), ProcArraySetReplicationSlotXmin(), process_syncing_tables_for_apply(), ProcKill(), ProcSleep(), ReadMultiXactCounts(), ReadMultiXactIdRange(), ReadNextFullTransactionId(), ReadNextMultiXactId(), ReadRecord(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePostInvalidate(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquireInternal(), 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(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), SerialSetActiveSerXmin(), set_indexsafe_procflags(), SetCommitTsLimit(), SetMultiXactIdLimit(), SetOffsetVacuumLimit(), SetTransactionIdLimit(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SignalVirtualTransaction(), SIInsertDataEntries(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SimpleLruWriteAll(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), ss_report_location(), StandbyRecoverPreparedTransactions(), StartBufferIO(), StartupCLOG(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), sts_parallel_scan_next(), SubTransGetParent(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SyncOneBuffer(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateBufferIO(), TerminateOtherDBBackends(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdGetStatus(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), update_cached_xid_range(), UpdateMinRecoveryPoint(), vac_truncate_clog(), vacuum_rel(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_relation_state_change(), wait_for_worker_state_change(), WaitForReplicationWorkerAttach(), WaitIO(), WaitOnLock(), write_relcache_init_file(), xact_redo(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), XLogFlush(), XLogNeedsFlush(), and XLogReportParameters().

1811 {
1812  LWLockMode mode;
1813  uint32 oldstate;
1814  bool check_waiters;
1815  int i;
1816 
1817  /*
1818  * Remove lock from list of locks held. Usually, but not always, it will
1819  * be the latest-acquired lock; so search array backwards.
1820  */
1821  for (i = num_held_lwlocks; --i >= 0;)
1822  if (lock == held_lwlocks[i].lock)
1823  break;
1824 
1825  if (i < 0)
1826  elog(ERROR, "lock %s is not held", T_NAME(lock));
1827 
1828  mode = held_lwlocks[i].mode;
1829 
1830  num_held_lwlocks--;
1831  for (; i < num_held_lwlocks; i++)
1832  held_lwlocks[i] = held_lwlocks[i + 1];
1833 
1834  PRINT_LWDEBUG("LWLockRelease", lock, mode);
1835 
1836  /*
1837  * Release my hold on lock, after that it can immediately be acquired by
1838  * others, even if we still have to wakeup other waiters.
1839  */
1840  if (mode == LW_EXCLUSIVE)
1841  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_EXCLUSIVE);
1842  else
1843  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_SHARED);
1844 
1845  /* nobody else can have that kind of lock */
1846  Assert(!(oldstate & LW_VAL_EXCLUSIVE));
1847 
1848 
1849  /*
1850  * We're still waiting for backends to get scheduled, don't wake them up
1851  * again.
1852  */
1853  if ((oldstate & (LW_FLAG_HAS_WAITERS | LW_FLAG_RELEASE_OK)) ==
1855  (oldstate & LW_LOCK_MASK) == 0)
1856  check_waiters = true;
1857  else
1858  check_waiters = false;
1859 
1860  /*
1861  * As waking up waiters requires the spinlock to be acquired, only do so
1862  * if necessary.
1863  */
1864  if (check_waiters)
1865  {
1866  /* XXX: remove before commit? */
1867  LOG_LWDEBUG("LWLockRelease", lock, "releasing waiters");
1868  LWLockWakeup(lock);
1869  }
1870 
1871  TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
1872 
1873  /*
1874  * Now okay to allow cancel/die interrupts.
1875  */
1877 }
#define T_NAME(lock)
Definition: lwlock.c:248
static PgChecksumMode mode
Definition: pg_checksums.c:61
LWLockMode
Definition: lwlock.h:130
#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:401
#define LW_LOCK_MASK
Definition: lwlock.c:106
#define LW_VAL_SHARED
Definition: lwlock.c:104
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:119
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
#define ERROR
Definition: elog.h:45
LWLockMode mode
Definition: lwlock.c:214
static void LWLockWakeup(LWLock *lock)
Definition: lwlock.c:960
unsigned int uint32
Definition: c.h:429
static int num_held_lwlocks
Definition: lwlock.c:217
#define Assert(condition)
Definition: c.h:792
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
#define elog(elevel,...)
Definition: elog.h:228
int i
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ LWLockReleaseAll()

void LWLockReleaseAll ( void  )

Definition at line 1909 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().

1910 {
1911  while (num_held_lwlocks > 0)
1912  {
1913  HOLD_INTERRUPTS(); /* match the upcoming RESUME_INTERRUPTS */
1914 
1916  }
1917 }
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1810
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
static int num_held_lwlocks
Definition: lwlock.c:217
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:117

◆ LWLockReleaseClearVar()

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

Definition at line 1883 of file lwlock.c.

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

Referenced by WALInsertLockRelease().

1884 {
1885  LWLockWaitListLock(lock);
1886 
1887  /*
1888  * Set the variable's value before releasing the lock, that prevents race
1889  * a race condition wherein a new locker acquires the lock, but hasn't yet
1890  * set the variables value.
1891  */
1892  *valptr = val;
1893  LWLockWaitListUnlock(lock);
1894 
1895  LWLockRelease(lock);
1896 }
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:947
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1810
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:895
long val
Definition: informix.c:664

◆ LWLockShmemSize()

Size LWLockShmemSize ( void  )

Definition at line 434 of file lwlock.c.

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

Referenced by CreateLWLocks(), and CreateSharedMemoryAndSemaphores().

435 {
436  Size size;
437  int i;
438  int numLocks = NUM_FIXED_LWLOCKS;
439 
440  /* Calculate total number of locks needed in the main array. */
441  numLocks += NumLWLocksForNamedTranches();
442 
443  /* Space for the LWLock array. */
444  size = mul_size(numLocks, sizeof(LWLockPadded));
445 
446  /* Space for dynamic allocation counter, plus room for alignment. */
447  size = add_size(size, sizeof(int) + LWLOCK_PADDED_SIZE);
448 
449  /* space for named tranches. */
451 
452  /* space for name of each tranche. */
453  for (i = 0; i < NamedLWLockTrancheRequests; i++)
454  size = add_size(size, strlen(NamedLWLockTrancheRequestArray[i].tranche_name) + 1);
455 
456  /* Disallow adding any more named tranches. */
458 
459  return size;
460 }
static bool lock_named_request_allowed
Definition: lwlock.c:241
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:127
int NamedLWLockTrancheRequests
Definition: lwlock.c:236
static int NumLWLocksForNamedTranches(void)
Definition: lwlock.c:419
Size mul_size(Size s1, Size s2)
Definition: shmem.c:519
Size add_size(Size s1, Size s2)
Definition: shmem.c:502
size_t Size
Definition: c.h:528
static NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:227
int i
#define LWLOCK_PADDED_SIZE
Definition: lwlock.h:72

◆ LWLockUpdateVar()

void LWLockUpdateVar ( LWLock lock,
uint64 *  valptr,
uint64  value 
)

Definition at line 1756 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().

1757 {
1758  proclist_head wakeup;
1759  proclist_mutable_iter iter;
1760 
1761  PRINT_LWDEBUG("LWLockUpdateVar", lock, LW_EXCLUSIVE);
1762 
1763  proclist_init(&wakeup);
1764 
1765  LWLockWaitListLock(lock);
1766 
1768 
1769  /* Update the lock's value */
1770  *valptr = val;
1771 
1772  /*
1773  * See if there are any LW_WAIT_UNTIL_FREE waiters that need to be woken
1774  * up. They are always in the front of the queue.
1775  */
1776  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
1777  {
1778  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1779 
1780  if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
1781  break;
1782 
1783  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
1784  proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
1785  }
1786 
1787  /* We are done updating shared state of the lock itself. */
1788  LWLockWaitListUnlock(lock);
1789 
1790  /*
1791  * Awaken any waiters I removed from the queue.
1792  */
1793  proclist_foreach_modify(iter, &wakeup, lwWaitLink)
1794  {
1795  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1796 
1797  proclist_delete(&wakeup, iter.cur, lwWaitLink);
1798  /* check comment in LWLockWakeup() about this barrier */
1799  pg_write_barrier();
1800  waiter->lwWaiting = false;
1801  PGSemaphoreUnlock(waiter->sem);
1802  }
1803 }
#define GetPGProcByNumber(n)
Definition: proc.h:365
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
proclist_head waiters
Definition: lwlock.h:35
bool lwWaiting
Definition: proc.h:170
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:947
#define proclist_foreach_modify(iter, lhead, link_member)
Definition: proclist.h:206
uint8 lwWaitMode
Definition: proc.h:171
pg_atomic_uint32 state
Definition: lwlock.h:34
#define proclist_delete(list, procno, link_member)
Definition: proclist.h:187
#define Assert(condition)
Definition: c.h:792
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define proclist_push_tail(list, procno, link_member)
Definition: proclist.h:191
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:895
#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:159
PGSemaphore sem
Definition: proc.h:127
Definition: proc.h:121
long val
Definition: informix.c:664
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:241

◆ LWLockWaitForVar()

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

Definition at line 1617 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().

1618 {
1619  PGPROC *proc = MyProc;
1620  int extraWaits = 0;
1621  bool result = false;
1622 #ifdef LWLOCK_STATS
1623  lwlock_stats *lwstats;
1624 
1625  lwstats = get_lwlock_stats_entry(lock);
1626 #endif
1627 
1628  PRINT_LWDEBUG("LWLockWaitForVar", lock, LW_WAIT_UNTIL_FREE);
1629 
1630  /*
1631  * Lock out cancel/die interrupts while we sleep on the lock. There is no
1632  * cleanup mechanism to remove us from the wait queue if we got
1633  * interrupted.
1634  */
1635  HOLD_INTERRUPTS();
1636 
1637  /*
1638  * Loop here to check the lock's status after each time we are signaled.
1639  */
1640  for (;;)
1641  {
1642  bool mustwait;
1643 
1644  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1645  &result);
1646 
1647  if (!mustwait)
1648  break; /* the lock was free or value didn't match */
1649 
1650  /*
1651  * Add myself to wait queue. Note that this is racy, somebody else
1652  * could wakeup before we're finished queuing. NB: We're using nearly
1653  * the same twice-in-a-row lock acquisition protocol as
1654  * LWLockAcquire(). Check its comments for details. The only
1655  * difference is that we also have to check the variable's values when
1656  * checking the state of the lock.
1657  */
1659 
1660  /*
1661  * Set RELEASE_OK flag, to make sure we get woken up as soon as the
1662  * lock is released.
1663  */
1665 
1666  /*
1667  * We're now guaranteed to be woken up if necessary. Recheck the lock
1668  * and variables state.
1669  */
1670  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1671  &result);
1672 
1673  /* Ok, no conflict after we queued ourselves. Undo queueing. */
1674  if (!mustwait)
1675  {
1676  LOG_LWDEBUG("LWLockWaitForVar", lock, "free, undoing queue");
1677 
1678  LWLockDequeueSelf(lock);
1679  break;
1680  }
1681 
1682  /*
1683  * Wait until awakened.
1684  *
1685  * Since we share the process wait semaphore with the regular lock
1686  * manager and ProcWaitForSignal, and we may need to acquire an LWLock
1687  * while one of those is pending, it is possible that we get awakened
1688  * for a reason other than being signaled by LWLockRelease. If so,
1689  * loop back and wait again. Once we've gotten the LWLock,
1690  * re-increment the sema by the number of additional signals received,
1691  * so that the lock manager or signal manager will see the received
1692  * signal when it next waits.
1693  */
1694  LOG_LWDEBUG("LWLockWaitForVar", lock, "waiting");
1695 
1696 #ifdef LWLOCK_STATS
1697  lwstats->block_count++;
1698 #endif
1699 
1700  LWLockReportWaitStart(lock);
1701  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE);
1702 
1703  for (;;)
1704  {
1705  PGSemaphoreLock(proc->sem);
1706  if (!proc->lwWaiting)
1707  break;
1708  extraWaits++;
1709  }
1710 
1711 #ifdef LOCK_DEBUG
1712  {
1713  /* not waiting anymore */
1714  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1715 
1716  Assert(nwaiters < MAX_BACKENDS);
1717  }
1718 #endif
1719 
1720  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE);
1722 
1723  LOG_LWDEBUG("LWLockWaitForVar", lock, "awakened");
1724 
1725  /* Now loop back and check the status of the lock again. */
1726  }
1727 
1728  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), LW_EXCLUSIVE);
1729 
1730  /*
1731  * Fix the process wait semaphore's count for any absorbed wakeups.
1732  */
1733  while (extraWaits-- > 0)
1734  PGSemaphoreUnlock(proc->sem);
1735 
1736  /*
1737  * Now okay to allow cancel/die interrupts.
1738  */
1740 
1741  return result;
1742 }
#define T_NAME(lock)
Definition: lwlock.c:248
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:343
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
PGPROC * MyProc
Definition: proc.c:68
bool lwWaiting
Definition: proc.h:170
pg_atomic_uint32 state
Definition: lwlock.h:34
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:119
#define MAX_BACKENDS
Definition: postmaster.h:75
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:770
unsigned int uint32
Definition: c.h:429
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1111
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:761
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1067
#define Assert(condition)
Definition: c.h:792
#define newval
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:320
static bool LWLockConflictsWithVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval, bool *result)
Definition: lwlock.c:1557
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:117
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:372
PGSemaphore sem
Definition: proc.h:127
Definition: proc.h:121
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:143
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ RequestNamedLWLockTranche()

void RequestNamedLWLockTranche ( const char *  tranche_name,
int  num_lwlocks 
)

Definition at line 703 of file lwlock.c.

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

Referenced by _PG_init().

704 {
705  NamedLWLockTrancheRequest *request;
706 
708  return; /* too late */
709 
710  if (NamedLWLockTrancheRequestArray == NULL)
711  {
716  * sizeof(NamedLWLockTrancheRequest));
717  }
718 
720  {
722 
723  while (i <= NamedLWLockTrancheRequests)
724  i *= 2;
725 
728  i * sizeof(NamedLWLockTrancheRequest));
730  }
731 
733  Assert(strlen(tranche_name) + 1 <= NAMEDATALEN);
734  strlcpy(request->tranche_name, tranche_name, NAMEDATALEN);
735  request->num_lwlocks = num_lwlocks;
737 }
static bool lock_named_request_allowed
Definition: lwlock.c:241
char tranche_name[NAMEDATALEN]
Definition: lwlock.c:223
#define NAMEDATALEN
int NamedLWLockTrancheRequests
Definition: lwlock.c:236
bool IsUnderPostmaster
Definition: globals.c:110
MemoryContext TopMemoryContext
Definition: mcxt.c:44
static int NamedLWLockTrancheRequestsAllocated
Definition: lwlock.c:228
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
#define Assert(condition)
Definition: c.h:792
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1070
static NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:227
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:797
int i

Variable Documentation

◆ MainLWLockArray

PGDLLIMPORT LWLockPadded* MainLWLockArray

Definition at line 200 of file lwlock.c.

Referenced by PostmasterMarkPIDForWorkerNotify().

◆ NamedLWLockTrancheArray

PGDLLIMPORT NamedLWLockTranche* NamedLWLockTrancheArray

Definition at line 239 of file lwlock.c.

Referenced by PostmasterMarkPIDForWorkerNotify().

◆ NamedLWLockTrancheRequests