path: root/src/backend/utils/activity/wait_event.c

/* ----------
 * wait_event.c
 *	  Wait event reporting infrastructure.
 *
 * Copyright (c) 2001-2022, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *	  src/backend/utils/activity/wait_event.c
 *
 * NOTES
 *
 * To make pgstat_report_wait_start() and pgstat_report_wait_end() as
 * lightweight as possible, they do not check if shared memory (MyProc
 * specifically, where the wait event is stored) is already available. Instead
 * we initially set my_wait_event_info to a process local variable, which then
 * is redirected to shared memory using pgstat_set_wait_event_storage(). For
 * the same reason pgstat_track_activities is not checked - the check adds
 * more work than it saves.
 *
 * ----------
 */
#include "postgres.h"

#include "storage/lmgr.h"		/* for GetLockNameFromTagType */
#include "storage/lwlock.h"		/* for GetLWLockIdentifier */
#include "utils/wait_event.h"


static const char *pgstat_get_wait_activity(WaitEventActivity w);
static const char *pgstat_get_wait_client(WaitEventClient w);
static const char *pgstat_get_wait_ipc(WaitEventIPC w);
static const char *pgstat_get_wait_timeout(WaitEventTimeout w);
static const char *pgstat_get_wait_io(WaitEventIO w);


static uint32 local_my_wait_event_info;
uint32	   *my_wait_event_info = &local_my_wait_event_info;


/*
 * Configure wait event reporting to report wait events to *wait_event_info.
 * *wait_event_info needs to be valid until pgstat_reset_wait_event_storage()
 * is called.
 *
 * Expected to be called during backend startup, to point my_wait_event_info
 * into shared memory.
 */
void
pgstat_set_wait_event_storage(uint32 *wait_event_info)
{
	my_wait_event_info = wait_event_info;
}

/*
 * Reset wait event storage location.
 *
 * Expected to be called during backend shutdown, before the location set up
 * pgstat_set_wait_event_storage() becomes invalid.
 */
void
pgstat_reset_wait_event_storage(void)
{
	my_wait_event_info = &local_my_wait_event_info;
}

/* ----------
 * pgstat_get_wait_event_type() -
 *
 *	Return a string representing the current wait event type, backend is
 *	waiting on.
 */
const char *
pgstat_get_wait_event_type(uint32 wait_event_info)
{
	uint32		classId;
	const char *event_type;

	/* report process as not waiting. */
	if (wait_event_info == 0)
		return NULL;

	classId = wait_event_info & 0xFF000000;

	switch (classId)
	{
		case PG_WAIT_LWLOCK:
			event_type = "LWLock";
			break;
		case PG_WAIT_LOCK:
			event_type = "Lock";
			break;
		case PG_WAIT_BUFFER_PIN:
			event_type = "BufferPin";
			break;
		case PG_WAIT_ACTIVITY:
			event_type = "Activity";
			break;
		case PG_WAIT_CLIENT:
			event_type = "Client";
			break;
		case PG_WAIT_EXTENSION:
			event_type = "Extension";
			break;
		case PG_WAIT_IPC:
			event_type = "IPC";
			break;
		case PG_WAIT_TIMEOUT:
			event_type = "Timeout";
			break;
		case PG_WAIT_IO:
			event_type = "IO";
			break;
		default:
			event_type = "???";
			break;
	}

	return event_type;
}

/* ----------
 * pgstat_get_wait_event() -
 *
 *	Return a string representing the current wait event, backend is
 *	waiting on.
 */
const char *
pgstat_get_wait_event(uint32 wait_event_info)
{
	uint32		classId;
	uint16		eventId;
	const char *event_name;

	/* report process as not waiting. */
	if (wait_event_info == 0)
		return NULL;

	classId = wait_event_info & 0xFF000000;
	eventId = wait_event_info & 0x0000FFFF;

	switch (classId)
	{
		case PG_WAIT_LWLOCK:
			event_name = GetLWLockIdentifier(classId, eventId);
			break;
		case PG_WAIT_LOCK:
			event_name = GetLockNameFromTagType(eventId);
			break;
		case PG_WAIT_BUFFER_PIN:
			event_name = "BufferPin";
			break;
		case PG_WAIT_ACTIVITY:
			{
				WaitEventActivity w = (WaitEventActivity) wait_event_info;

				event_name = pgstat_get_wait_activity(w);
				break;
			}
		case PG_WAIT_CLIENT:
			{
				WaitEventClient w = (WaitEventClient) wait_event_info;

				event_name = pgstat_get_wait_client(w);
				break;
			}
		case PG_WAIT_EXTENSION:
			event_name = "Extension";
			break;
		case PG_WAIT_IPC:
			{
				WaitEventIPC w = (WaitEventIPC) wait_event_info;

				event_name = pgstat_get_wait_ipc(w);
				break;
			}
		case PG_WAIT_TIMEOUT:
			{
				WaitEventTimeout w = (WaitEventTimeout) wait_event_info;

				event_name = pgstat_get_wait_timeout(w);
				break;
			}
		case PG_WAIT_IO:
			{
				WaitEventIO w = (WaitEventIO) wait_event_info;

				event_name = pgstat_get_wait_io(w);
				break;
			}
		default:
			event_name = "unknown wait event";
			break;
	}

	return event_name;
}

/* ----------
 * pgstat_get_wait_activity() -
 *
 * Convert WaitEventActivity to string.
 * ----------
 */
static const char *
pgstat_get_wait_activity(WaitEventActivity w)
{
	const char *event_name = "unknown wait event";

	switch (w)
	{
		case WAIT_EVENT_ARCHIVER_MAIN:
			event_name = "ArchiverMain";
			break;
		case WAIT_EVENT_AUTOVACUUM_MAIN:
			event_name = "AutoVacuumMain";
			break;
		case WAIT_EVENT_BGWRITER_HIBERNATE:
			event_name = "BgWriterHibernate";
			break;
		case WAIT_EVENT_BGWRITER_MAIN:
			event_name = "BgWriterMain";
			break;
		case WAIT_EVENT_CHECKPOINTER_MAIN:
			event_name = "CheckpointerMain";
			break;
		case WAIT_EVENT_LOGICAL_APPLY_MAIN:
			event_name = "LogicalApplyMain";
			break;
		case WAIT_EVENT_LOGICAL_LAUNCHER_MAIN:
			event_name = "LogicalLauncherMain";
			break;
		case WAIT_EVENT_RECOVERY_WAL_STREAM:
			event_name = "RecoveryWalStream";
			break;
		case WAIT_EVENT_SYSLOGGER_MAIN:
			event_name = "SysLoggerMain";
			break;
		case WAIT_EVENT_WAL_RECEIVER_MAIN:
			event_name = "WalReceiverMain";
			break;
		case WAIT_EVENT_WAL_SENDER_MAIN:
			event_name = "WalSenderMain";
			break;
		case WAIT_EVENT_WAL_WRITER_MAIN:
			event_name = "WalWriterMain";
			break;
			/* no default case, so that compiler will warn */
	}

	return event_name;
}

/* ----------
 * pgstat_get_wait_client() -
 *
 * Convert WaitEventClient to string.
 * ----------
 */
static const char *
pgstat_get_wait_client(WaitEventClient w)
{
	const char *event_name = "unknown wait event";

	switch (w)
	{
		case WAIT_EVENT_CLIENT_READ:
			event_name = "ClientRead";
			break;
		case WAIT_EVENT_CLIENT_WRITE:
			event_name = "ClientWrite";
			break;
		case WAIT_EVENT_GSS_OPEN_SERVER:
			event_name = "GSSOpenServer";
			break;
		case WAIT_EVENT_LIBPQWALRECEIVER_CONNECT:
			event_name = "LibPQWalReceiverConnect";
			break;
		case WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE:
			event_name = "LibPQWalReceiverReceive";
			break;
		case WAIT_EVENT_SSL_OPEN_SERVER:
			event_name = "SSLOpenServer";
			break;
		case WAIT_EVENT_WAL_SENDER_WAIT_WAL:
			event_name = "WalSenderWaitForWAL";
			break;
		case WAIT_EVENT_WAL_SENDER_WRITE_DATA:
			event_name = "WalSenderWriteData";
			break;
			/* no default case, so that compiler will warn */
	}

	return event_name;
}

/* ----------
 * pgstat_get_wait_ipc() -
 *
 * Convert WaitEventIPC to string.
 * ----------
 */
static const char *
pgstat_get_wait_ipc(WaitEventIPC w)
{
	const char *event_name = "unknown wait event";

	switch (w)
	{
		case WAIT_EVENT_APPEND_READY:
			event_name = "AppendReady";
			break;
		case WAIT_EVENT_ARCHIVE_CLEANUP_COMMAND:
			event_name = "ArchiveCleanupCommand";
			break;
		case WAIT_EVENT_ARCHIVE_COMMAND:
			event_name = "ArchiveCommand";
			break;
		case WAIT_EVENT_BACKEND_TERMINATION:
			event_name = "BackendTermination";
			break;
		case WAIT_EVENT_BACKUP_WAIT_WAL_ARCHIVE:
			event_name = "BackupWaitWalArchive";
			break;
		case WAIT_EVENT_BGWORKER_SHUTDOWN:
			event_name = "BgWorkerShutdown";
			break;
		case WAIT_EVENT_BGWORKER_STARTUP:
			event_name = "BgWorkerStartup";
			break;
		case WAIT_EVENT_BTREE_PAGE:
			event_name = "BtreePage";
			break;
		case WAIT_EVENT_BUFFER_IO:
			event_name = "BufferIO";
			break;
		case WAIT_EVENT_CHECKPOINT_DONE:
			event_name = "CheckpointDone";
			break;
		case WAIT_EVENT_CHECKPOINT_START:
			event_name = "CheckpointStart";
			break;
		case WAIT_EVENT_EXECUTE_GATHER:
			event_name = "ExecuteGather";
			break;
		case WAIT_EVENT_HASH_BATCH_ALLOCATE:
			event_name = "HashBatchAllocate";
			break;
		case WAIT_EVENT_HASH_BATCH_ELECT:
			event_name = "HashBatchElect";
			break;
		case WAIT_EVENT_HASH_BATCH_LOAD:
			event_name = "HashBatchLoad";
			break;
		case WAIT_EVENT_HASH_BUILD_ALLOCATE:
			event_name = "HashBuildAllocate";
			break;
		case WAIT_EVENT_HASH_BUILD_ELECT:
			event_name = "HashBuildElect";
			break;
		case WAIT_EVENT_HASH_BUILD_HASH_INNER:
			event_name = "HashBuildHashInner";
			break;
		case WAIT_EVENT_HASH_BUILD_HASH_OUTER:
			event_name = "HashBuildHashOuter";
			break;
		case WAIT_EVENT_HASH_GROW_BATCHES_ALLOCATE:
			event_name = "HashGrowBatchesAllocate";
			break;
		case WAIT_EVENT_HASH_GROW_BATCHES_DECIDE:
			event_name = "HashGrowBatchesDecide";
			break;
		case WAIT_EVENT_HASH_GROW_BATCHES_ELECT:
			event_name = "HashGrowBatchesElect";
			break;
		case WAIT_EVENT_HASH_GROW_BATCHES_FINISH:
			event_name = "HashGrowBatchesFinish";
			break;
		case WAIT_EVENT_HASH_GROW_BATCHES_REPARTITION:
			event_name = "HashGrowBatchesRepartition";
			break;
		case WAIT_EVENT_HASH_GROW_BUCKETS_ALLOCATE:
			event_name = "HashGrowBucketsAllocate";
			break;
		case WAIT_EVENT_HASH_GROW_BUCKETS_ELECT:
			event_name = "HashGrowBucketsElect";
			break;
		case WAIT_EVENT_HASH_GROW_BUCKETS_REINSERT:
			event_name = "HashGrowBucketsReinsert";
			break;
		case WAIT_EVENT_LOGICAL_SYNC_DATA:
			event_name = "LogicalSyncData";
			break;
		case WAIT_EVENT_LOGICAL_SYNC_STATE_CHANGE:
			event_name = "LogicalSyncStateChange";
			break;
		case WAIT_EVENT_MQ_INTERNAL:
			event_name = "MessageQueueInternal";
			break;
		case WAIT_EVENT_MQ_PUT_MESSAGE:
			event_name = "MessageQueuePutMessage";
			break;
		case WAIT_EVENT_MQ_RECEIVE:
			event_name = "MessageQueueReceive";
			break;
		case WAIT_EVENT_MQ_SEND:
			event_name = "MessageQueueSend";
			break;
		case WAIT_EVENT_PARALLEL_BITMAP_SCAN:
			event_name = "ParallelBitmapScan";
			break;
		case WAIT_EVENT_PARALLEL_CREATE_INDEX_SCAN:
			event_name = "ParallelCreateIndexScan";
			break;
		case WAIT_EVENT_PARALLEL_FINISH:
			event_name = "ParallelFinish";
			break;
		case WAIT_EVENT_PROCARRAY_GROUP_UPDATE:
			event_name = "ProcArrayGroupUpdate";
			break;
		case WAIT_EVENT_PROC_SIGNAL_BARRIER:
			event_name = "ProcSignalBarrier";
			break;
		case WAIT_EVENT_PROMOTE:
			event_name = "Promote";
			break;
		case WAIT_EVENT_RECOVERY_CONFLICT_SNAPSHOT:
			event_name = "RecoveryConflictSnapshot";
			break;
		case WAIT_EVENT_RECOVERY_CONFLICT_TABLESPACE:
			event_name = "RecoveryConflictTablespace";
			break;
		case WAIT_EVENT_RECOVERY_END_COMMAND:
			event_name = "RecoveryEndCommand";
			break;
		case WAIT_EVENT_RECOVERY_PAUSE:
			event_name = "RecoveryPause";
			break;
		case WAIT_EVENT_REPLICATION_ORIGIN_DROP:
			event_name = "ReplicationOriginDrop";
			break;
		case WAIT_EVENT_REPLICATION_SLOT_DROP:
			event_name = "ReplicationSlotDrop";
			break;
		case WAIT_EVENT_RESTORE_COMMAND:
			event_name = "RestoreCommand";
			break;
		case WAIT_EVENT_SAFE_SNAPSHOT:
			event_name = "SafeSnapshot";
			break;
		case WAIT_EVENT_SYNC_REP:
			event_name = "SyncRep";
			break;
		case WAIT_EVENT_WAL_RECEIVER_EXIT:
			event_name = "WalReceiverExit";
			break;
		case WAIT_EVENT_WAL_RECEIVER_WAIT_START:
			event_name = "WalReceiverWaitStart";
			break;
		case WAIT_EVENT_XACT_GROUP_UPDATE:
			event_name = "XactGroupUpdate";
			break;
			/* no default case, so that compiler will warn */
	}

	return event_name;
}

/* ----------
 * pgstat_get_wait_timeout() -
 *
 * Convert WaitEventTimeout to string.
 * ----------
 */
static const char *
pgstat_get_wait_timeout(WaitEventTimeout w)
{
	const char *event_name = "unknown wait event";

	switch (w)
	{
		case WAIT_EVENT_BASE_BACKUP_THROTTLE:
			event_name = "BaseBackupThrottle";
			break;
		case WAIT_EVENT_CHECKPOINT_WRITE_DELAY:
			event_name = "CheckpointWriteDelay";
			break;
		case WAIT_EVENT_PG_SLEEP:
			event_name = "PgSleep";
			break;
		case WAIT_EVENT_RECOVERY_APPLY_DELAY:
			event_name = "RecoveryApplyDelay";
			break;
		case WAIT_EVENT_RECOVERY_RETRIEVE_RETRY_INTERVAL:
			event_name = "RecoveryRetrieveRetryInterval";
			break;
		case WAIT_EVENT_REGISTER_SYNC_REQUEST:
			event_name = "RegisterSyncRequest";
			break;
		case WAIT_EVENT_VACUUM_DELAY:
			event_name = "VacuumDelay";
			break;
		case WAIT_EVENT_VACUUM_TRUNCATE:
			event_name = "VacuumTruncate";
			break;
			/* no default case, so that compiler will warn */
	}

	return event_name;
}

/* ----------
 * pgstat_get_wait_io() -
 *
 * Convert WaitEventIO to string.
 * ----------
 */
static const char *
pgstat_get_wait_io(WaitEventIO w)
{
	const char *event_name = "unknown wait event";

	switch (w)
	{
		case WAIT_EVENT_BASEBACKUP_READ:
			event_name = "BaseBackupRead";
			break;
		case WAIT_EVENT_BASEBACKUP_SYNC:
			event_name = "BaseBackupSync";
			break;
		case WAIT_EVENT_BASEBACKUP_WRITE:
			event_name = "BaseBackupWrite";
			break;
		case WAIT_EVENT_BUFFILE_READ:
			event_name = "BufFileRead";
			break;
		case WAIT_EVENT_BUFFILE_WRITE:
			event_name = "BufFileWrite";
			break;
		case WAIT_EVENT_BUFFILE_TRUNCATE:
			event_name = "BufFileTruncate";
			break;
		case WAIT_EVENT_CONTROL_FILE_READ:
			event_name = "ControlFileRead";
			break;
		case WAIT_EVENT_CONTROL_FILE_SYNC:
			event_name = "ControlFileSync";
			break;
		case WAIT_EVENT_CONTROL_FILE_SYNC_UPDATE:
			event_name = "ControlFileSyncUpdate";
			break;
		case WAIT_EVENT_CONTROL_FILE_WRITE:
			event_name = "ControlFileWrite";
			break;
		case WAIT_EVENT_CONTROL_FILE_WRITE_UPDATE:
			event_name = "ControlFileWriteUpdate";
			break;
		case WAIT_EVENT_COPY_FILE_READ:
			event_name = "CopyFileRead";
			break;
		case WAIT_EVENT_COPY_FILE_WRITE:
			event_name = "CopyFileWrite";
			break;
		case WAIT_EVENT_DATA_FILE_EXTEND:
			event_name = "DataFileExtend";
			break;
		case WAIT_EVENT_DATA_FILE_FLUSH:
			event_name = "DataFileFlush";
			break;
		case WAIT_EVENT_DATA_FILE_IMMEDIATE_SYNC:
			event_name = "DataFileImmediateSync";
			break;
		case WAIT_EVENT_DATA_FILE_PREFETCH:
			event_name = "DataFilePrefetch";
			break;
		case WAIT_EVENT_DATA_FILE_READ:
			event_name = "DataFileRead";
			break;
		case WAIT_EVENT_DATA_FILE_SYNC:
			event_name = "DataFileSync";
			break;
		case WAIT_EVENT_DATA_FILE_TRUNCATE:
			event_name = "DataFileTruncate";
			break;
		case WAIT_EVENT_DATA_FILE_WRITE:
			event_name = "DataFileWrite";
			break;
		case WAIT_EVENT_DSM_FILL_ZERO_WRITE:
			event_name = "DSMFillZeroWrite";
			break;
		case WAIT_EVENT_LOCK_FILE_ADDTODATADIR_READ:
			event_name = "LockFileAddToDataDirRead";
			break;
		case WAIT_EVENT_LOCK_FILE_ADDTODATADIR_SYNC:
			event_name = "LockFileAddToDataDirSync";
			break;
		case WAIT_EVENT_LOCK_FILE_ADDTODATADIR_WRITE:
			event_name = "LockFileAddToDataDirWrite";
			break;
		case WAIT_EVENT_LOCK_FILE_CREATE_READ:
			event_name = "LockFileCreateRead";
			break;
		case WAIT_EVENT_LOCK_FILE_CREATE_SYNC:
			event_name = "LockFileCreateSync";
			break;
		case WAIT_EVENT_LOCK_FILE_CREATE_WRITE:
			event_name = "LockFileCreateWrite";
			break;
		case WAIT_EVENT_LOCK_FILE_RECHECKDATADIR_READ:
			event_name = "LockFileReCheckDataDirRead";
			break;
		case WAIT_EVENT_LOGICAL_REWRITE_CHECKPOINT_SYNC:
			event_name = "LogicalRewriteCheckpointSync";
			break;
		case WAIT_EVENT_LOGICAL_REWRITE_MAPPING_SYNC:
			event_name = "LogicalRewriteMappingSync";
			break;
		case WAIT_EVENT_LOGICAL_REWRITE_MAPPING_WRITE:
			event_name = "LogicalRewriteMappingWrite";
			break;
		case WAIT_EVENT_LOGICAL_REWRITE_SYNC:
			event_name = "LogicalRewriteSync";
			break;
		case WAIT_EVENT_LOGICAL_REWRITE_TRUNCATE:
			event_name = "LogicalRewriteTruncate";
			break;
		case WAIT_EVENT_LOGICAL_REWRITE_WRITE:
			event_name = "LogicalRewriteWrite";
			break;
		case WAIT_EVENT_RELATION_MAP_READ:
			event_name = "RelationMapRead";
			break;
		case WAIT_EVENT_RELATION_MAP_SYNC:
			event_name = "RelationMapSync";
			break;
		case WAIT_EVENT_RELATION_MAP_WRITE:
			event_name = "RelationMapWrite";
			break;
		case WAIT_EVENT_REORDER_BUFFER_READ:
			event_name = "ReorderBufferRead";
			break;
		case WAIT_EVENT_REORDER_BUFFER_WRITE:
			event_name = "ReorderBufferWrite";
			break;
		case WAIT_EVENT_REORDER_LOGICAL_MAPPING_READ:
			event_name = "ReorderLogicalMappingRead";
			break;
		case WAIT_EVENT_REPLICATION_SLOT_READ:
			event_name = "ReplicationSlotRead";
			break;
		case WAIT_EVENT_REPLICATION_SLOT_RESTORE_SYNC:
			event_name = "ReplicationSlotRestoreSync";
			break;
		case WAIT_EVENT_REPLICATION_SLOT_SYNC:
			event_name = "ReplicationSlotSync";
			break;
		case WAIT_EVENT_REPLICATION_SLOT_WRITE:
			event_name = "ReplicationSlotWrite";
			break;
		case WAIT_EVENT_SLRU_FLUSH_SYNC:
			event_name = "SLRUFlushSync";
			break;
		case WAIT_EVENT_SLRU_READ:
			event_name = "SLRURead";
			break;
		case WAIT_EVENT_SLRU_SYNC:
			event_name = "SLRUSync";
			break;
		case WAIT_EVENT_SLRU_WRITE:
			event_name = "SLRUWrite";
			break;
		case WAIT_EVENT_SNAPBUILD_READ:
			event_name = "SnapbuildRead";
			break;
		case WAIT_EVENT_SNAPBUILD_SYNC:
			event_name = "SnapbuildSync";
			break;
		case WAIT_EVENT_SNAPBUILD_WRITE:
			event_name = "SnapbuildWrite";
			break;
		case WAIT_EVENT_TIMELINE_HISTORY_FILE_SYNC:
			event_name = "TimelineHistoryFileSync";
			break;
		case WAIT_EVENT_TIMELINE_HISTORY_FILE_WRITE:
			event_name = "TimelineHistoryFileWrite";
			break;
		case WAIT_EVENT_TIMELINE_HISTORY_READ:
			event_name = "TimelineHistoryRead";
			break;
		case WAIT_EVENT_TIMELINE_HISTORY_SYNC:
			event_name = "TimelineHistorySync";
			break;
		case WAIT_EVENT_TIMELINE_HISTORY_WRITE:
			event_name = "TimelineHistoryWrite";
			break;
		case WAIT_EVENT_TWOPHASE_FILE_READ:
			event_name = "TwophaseFileRead";
			break;
		case WAIT_EVENT_TWOPHASE_FILE_SYNC:
			event_name = "TwophaseFileSync";
			break;
		case WAIT_EVENT_TWOPHASE_FILE_WRITE:
			event_name = "TwophaseFileWrite";
			break;
		case WAIT_EVENT_VERSION_FILE_SYNC:
			event_name = "VersionFileSync";
			break;
		case WAIT_EVENT_VERSION_FILE_WRITE:
			event_name = "VersionFileWrite";
			break;
		case WAIT_EVENT_WALSENDER_TIMELINE_HISTORY_READ:
			event_name = "WALSenderTimelineHistoryRead";
			break;
		case WAIT_EVENT_WAL_BOOTSTRAP_SYNC:
			event_name = "WALBootstrapSync";
			break;
		case WAIT_EVENT_WAL_BOOTSTRAP_WRITE:
			event_name = "WALBootstrapWrite";
			break;
		case WAIT_EVENT_WAL_COPY_READ:
			event_name = "WALCopyRead";
			break;
		case WAIT_EVENT_WAL_COPY_SYNC:
			event_name = "WALCopySync";
			break;
		case WAIT_EVENT_WAL_COPY_WRITE:
			event_name = "WALCopyWrite";
			break;
		case WAIT_EVENT_WAL_INIT_SYNC:
			event_name = "WALInitSync";
			break;
		case WAIT_EVENT_WAL_INIT_WRITE:
			event_name = "WALInitWrite";
			break;
		case WAIT_EVENT_WAL_READ:
			event_name = "WALRead";
			break;
		case WAIT_EVENT_WAL_SYNC:
			event_name = "WALSync";
			break;
		case WAIT_EVENT_WAL_SYNC_METHOD_ASSIGN:
			event_name = "WALSyncMethodAssign";
			break;
		case WAIT_EVENT_WAL_WRITE:
			event_name = "WALWrite";
			break;

			/* no default case, so that compiler will warn */
	}

	return event_name;
}