Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 2023 insertions, 0 deletions

diff --git a/src/backend/utils/activity/Makefile b/src/backend/utils/activity/Makefile
new file mode 100644
index 0000000..59196f2
--- /dev/null
+++ b/src/backend/utils/activity/Makefile
@@ -0,0 +1,21 @@
+#-------------------------------------------------------------------------
+#
+# Makefile for backend/utils/activity
+#
+# Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+# Portions Copyright (c) 1994, Regents of the University of California
+#
+# src/backend/utils/activity/Makefile
+#
+#-------------------------------------------------------------------------
+
+subdir = src/backend/utils/activity
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+
+OBJS = \
+	backend_progress.o \
+	backend_status.o \
+	wait_event.o
+
+include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/utils/activity/backend_progress.c b/src/backend/utils/activity/backend_progress.c
new file mode 100644
index 0000000..6743e68
--- /dev/null
+++ b/src/backend/utils/activity/backend_progress.c
@@ -0,0 +1,112 @@
+/* ----------
+ * progress.c
+ *
+ *	Command progress reporting infrastructure.
+ *
+ *	Copyright (c) 2001-2021, PostgreSQL Global Development Group
+ *
+ *	src/backend/postmaster/progress.c
+ * ----------
+ */
+#include "postgres.h"
+
+#include "port/atomics.h"		/* for memory barriers */
+#include "utils/backend_progress.h"
+#include "utils/backend_status.h"
+
+
+/*-----------
+ * pgstat_progress_start_command() -
+ *
+ * Set st_progress_command (and st_progress_command_target) in own backend
+ * entry.  Also, zero-initialize st_progress_param array.
+ *-----------
+ */
+void
+pgstat_progress_start_command(ProgressCommandType cmdtype, Oid relid)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+
+	if (!beentry || !pgstat_track_activities)
+		return;
+
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+	beentry->st_progress_command = cmdtype;
+	beentry->st_progress_command_target = relid;
+	MemSet(&beentry->st_progress_param, 0, sizeof(beentry->st_progress_param));
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
+
+/*-----------
+ * pgstat_progress_update_param() -
+ *
+ * Update index'th member in st_progress_param[] of own backend entry.
+ *-----------
+ */
+void
+pgstat_progress_update_param(int index, int64 val)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+
+	Assert(index >= 0 && index < PGSTAT_NUM_PROGRESS_PARAM);
+
+	if (!beentry || !pgstat_track_activities)
+		return;
+
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+	beentry->st_progress_param[index] = val;
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
+
+/*-----------
+ * pgstat_progress_update_multi_param() -
+ *
+ * Update multiple members in st_progress_param[] of own backend entry.
+ * This is atomic; readers won't see intermediate states.
+ *-----------
+ */
+void
+pgstat_progress_update_multi_param(int nparam, const int *index,
+								   const int64 *val)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+	int			i;
+
+	if (!beentry || !pgstat_track_activities || nparam == 0)
+		return;
+
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+
+	for (i = 0; i < nparam; ++i)
+	{
+		Assert(index[i] >= 0 && index[i] < PGSTAT_NUM_PROGRESS_PARAM);
+
+		beentry->st_progress_param[index[i]] = val[i];
+	}
+
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
+
+/*-----------
+ * pgstat_progress_end_command() -
+ *
+ * Reset st_progress_command (and st_progress_command_target) in own backend
+ * entry.  This signals the end of the command.
+ *-----------
+ */
+void
+pgstat_progress_end_command(void)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+
+	if (!beentry || !pgstat_track_activities)
+		return;
+
+	if (beentry->st_progress_command == PROGRESS_COMMAND_INVALID)
+		return;
+
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+	beentry->st_progress_command = PROGRESS_COMMAND_INVALID;
+	beentry->st_progress_command_target = InvalidOid;
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
diff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c
new file mode 100644
index 0000000..7229598
--- /dev/null
+++ b/src/backend/utils/activity/backend_status.c
@@ -0,0 +1,1150 @@
+/* ----------
+ * backend_status.c
+ *	  Backend status reporting infrastructure.
+ *
+ * Copyright (c) 2001-2021, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/postmaster/backend_status.c
+ * ----------
+ */
+#include "postgres.h"
+
+#include "access/xact.h"
+#include "libpq/libpq.h"
+#include "miscadmin.h"
+#include "pg_trace.h"
+#include "pgstat.h"
+#include "port/atomics.h"		/* for memory barriers */
+#include "storage/ipc.h"
+#include "storage/proc.h"		/* for MyProc */
+#include "storage/sinvaladt.h"
+#include "utils/ascii.h"
+#include "utils/backend_status.h"
+#include "utils/guc.h"			/* for application_name */
+#include "utils/memutils.h"
+
+
+/* ----------
+ * Total number of backends including auxiliary
+ *
+ * We reserve a slot for each possible BackendId, plus one for each
+ * possible auxiliary process type.  (This scheme assumes there is not
+ * more than one of any auxiliary process type at a time.) MaxBackends
+ * includes autovacuum workers and background workers as well.
+ * ----------
+ */
+#define NumBackendStatSlots (MaxBackends + NUM_AUXPROCTYPES)
+
+
+/* ----------
+ * GUC parameters
+ * ----------
+ */
+bool		pgstat_track_activities = false;
+int			pgstat_track_activity_query_size = 1024;
+
+
+/* exposed so that backend_progress.c can access it */
+PgBackendStatus *MyBEEntry = NULL;
+
+
+static PgBackendStatus *BackendStatusArray = NULL;
+static char *BackendAppnameBuffer = NULL;
+static char *BackendClientHostnameBuffer = NULL;
+static char *BackendActivityBuffer = NULL;
+static Size BackendActivityBufferSize = 0;
+#ifdef USE_SSL
+static PgBackendSSLStatus *BackendSslStatusBuffer = NULL;
+#endif
+#ifdef ENABLE_GSS
+static PgBackendGSSStatus *BackendGssStatusBuffer = NULL;
+#endif
+
+
+/* Status for backends including auxiliary */
+static LocalPgBackendStatus *localBackendStatusTable = NULL;
+
+/* Total number of backends including auxiliary */
+static int	localNumBackends = 0;
+
+static MemoryContext backendStatusSnapContext;
+
+
+static void pgstat_beshutdown_hook(int code, Datum arg);
+static void pgstat_read_current_status(void);
+static void pgstat_setup_backend_status_context(void);
+
+
+/*
+ * Report shared-memory space needed by CreateSharedBackendStatus.
+ */
+Size
+BackendStatusShmemSize(void)
+{
+	Size		size;
+
+	/* BackendStatusArray: */
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
+	/* BackendAppnameBuffer: */
+	size = add_size(size,
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
+	/* BackendClientHostnameBuffer: */
+	size = add_size(size,
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
+	/* BackendActivityBuffer: */
+	size = add_size(size,
+					mul_size(pgstat_track_activity_query_size, NumBackendStatSlots));
+#ifdef USE_SSL
+	/* BackendSslStatusBuffer: */
+	size = add_size(size,
+					mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots));
+#endif
+#ifdef ENABLE_GSS
+	/* BackendGssStatusBuffer: */
+	size = add_size(size,
+					mul_size(sizeof(PgBackendGSSStatus), NumBackendStatSlots));
+#endif
+	return size;
+}
+
+/*
+ * Initialize the shared status array and several string buffers
+ * during postmaster startup.
+ */
+void
+CreateSharedBackendStatus(void)
+{
+	Size		size;
+	bool		found;
+	int			i;
+	char	   *buffer;
+
+	/* Create or attach to the shared array */
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
+	BackendStatusArray = (PgBackendStatus *)
+		ShmemInitStruct("Backend Status Array", size, &found);
+
+	if (!found)
+	{
+		/*
+		 * We're the first - initialize.
+		 */
+		MemSet(BackendStatusArray, 0, size);
+	}
+
+	/* Create or attach to the shared appname buffer */
+	size = mul_size(NAMEDATALEN, NumBackendStatSlots);
+	BackendAppnameBuffer = (char *)
+		ShmemInitStruct("Backend Application Name Buffer", size, &found);
+
+	if (!found)
+	{
+		MemSet(BackendAppnameBuffer, 0, size);
+
+		/* Initialize st_appname pointers. */
+		buffer = BackendAppnameBuffer;
+		for (i = 0; i < NumBackendStatSlots; i++)
+		{
+			BackendStatusArray[i].st_appname = buffer;
+			buffer += NAMEDATALEN;
+		}
+	}
+
+	/* Create or attach to the shared client hostname buffer */
+	size = mul_size(NAMEDATALEN, NumBackendStatSlots);
+	BackendClientHostnameBuffer = (char *)
+		ShmemInitStruct("Backend Client Host Name Buffer", size, &found);
+
+	if (!found)
+	{
+		MemSet(BackendClientHostnameBuffer, 0, size);
+
+		/* Initialize st_clienthostname pointers. */
+		buffer = BackendClientHostnameBuffer;
+		for (i = 0; i < NumBackendStatSlots; i++)
+		{
+			BackendStatusArray[i].st_clienthostname = buffer;
+			buffer += NAMEDATALEN;
+		}
+	}
+
+	/* Create or attach to the shared activity buffer */
+	BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
+										 NumBackendStatSlots);
+	BackendActivityBuffer = (char *)
+		ShmemInitStruct("Backend Activity Buffer",
+						BackendActivityBufferSize,
+						&found);
+
+	if (!found)
+	{
+		MemSet(BackendActivityBuffer, 0, BackendActivityBufferSize);
+
+		/* Initialize st_activity pointers. */
+		buffer = BackendActivityBuffer;
+		for (i = 0; i < NumBackendStatSlots; i++)
+		{
+			BackendStatusArray[i].st_activity_raw = buffer;
+			buffer += pgstat_track_activity_query_size;
+		}
+	}
+
+#ifdef USE_SSL
+	/* Create or attach to the shared SSL status buffer */
+	size = mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots);
+	BackendSslStatusBuffer = (PgBackendSSLStatus *)
+		ShmemInitStruct("Backend SSL Status Buffer", size, &found);
+
+	if (!found)
+	{
+		PgBackendSSLStatus *ptr;
+
+		MemSet(BackendSslStatusBuffer, 0, size);
+
+		/* Initialize st_sslstatus pointers. */
+		ptr = BackendSslStatusBuffer;
+		for (i = 0; i < NumBackendStatSlots; i++)
+		{
+			BackendStatusArray[i].st_sslstatus = ptr;
+			ptr++;
+		}
+	}
+#endif
+
+#ifdef ENABLE_GSS
+	/* Create or attach to the shared GSSAPI status buffer */
+	size = mul_size(sizeof(PgBackendGSSStatus), NumBackendStatSlots);
+	BackendGssStatusBuffer = (PgBackendGSSStatus *)
+		ShmemInitStruct("Backend GSS Status Buffer", size, &found);
+
+	if (!found)
+	{
+		PgBackendGSSStatus *ptr;
+
+		MemSet(BackendGssStatusBuffer, 0, size);
+
+		/* Initialize st_gssstatus pointers. */
+		ptr = BackendGssStatusBuffer;
+		for (i = 0; i < NumBackendStatSlots; i++)
+		{
+			BackendStatusArray[i].st_gssstatus = ptr;
+			ptr++;
+		}
+	}
+#endif
+}
+
+/*
+ * Initialize pgstats backend activity state, and set up our on-proc-exit
+ * hook.  Called from InitPostgres and AuxiliaryProcessMain. For auxiliary
+ * process, MyBackendId is invalid. Otherwise, MyBackendId must be set, but we
+ * must not have started any transaction yet (since the exit hook must run
+ * after the last transaction exit).
+ *
+ * NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
+ */
+void
+pgstat_beinit(void)
+{
+	/* Initialize MyBEEntry */
+	if (MyBackendId != InvalidBackendId)
+	{
+		Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
+		MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+
+		/*
+		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
+		 * have a BackendId, the slot is statically allocated based on the
+		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
+		 * in the range from 1 to MaxBackends (inclusive), so we use
+		 * MaxBackends + AuxBackendType + 1 as the index of the slot for an
+		 * auxiliary process.
+		 */
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+	}
+
+	/* Set up a process-exit hook to clean up */
+	on_shmem_exit(pgstat_beshutdown_hook, 0);
+}
+
+
+/* ----------
+ * pgstat_bestart() -
+ *
+ *	Initialize this backend's entry in the PgBackendStatus array.
+ *	Called from InitPostgres.
+ *
+ *	Apart from auxiliary processes, MyBackendId, MyDatabaseId,
+ *	session userid, and application_name must be set for a
+ *	backend (hence, this cannot be combined with pgbestat_beinit).
+ *	Note also that we must be inside a transaction if this isn't an aux
+ *	process, as we may need to do encoding conversion on some strings.
+ * ----------
+ */
+void
+pgstat_bestart(void)
+{
+	volatile PgBackendStatus *vbeentry = MyBEEntry;
+	PgBackendStatus lbeentry;
+#ifdef USE_SSL
+	PgBackendSSLStatus lsslstatus;
+#endif
+#ifdef ENABLE_GSS
+	PgBackendGSSStatus lgssstatus;
+#endif
+
+	/* pgstats state must be initialized from pgstat_beinit() */
+	Assert(vbeentry != NULL);
+
+	/*
+	 * To minimize the time spent modifying the PgBackendStatus entry, and
+	 * avoid risk of errors inside the critical section, we first copy the
+	 * shared-memory struct to a local variable, then modify the data in the
+	 * local variable, then copy the local variable back to shared memory.
+	 * Only the last step has to be inside the critical section.
+	 *
+	 * Most of the data we copy from shared memory is just going to be
+	 * overwritten, but the struct's not so large that it's worth the
+	 * maintenance hassle to copy only the needful fields.
+	 */
+	memcpy(&lbeentry,
+		   unvolatize(PgBackendStatus *, vbeentry),
+		   sizeof(PgBackendStatus));
+
+	/* These structs can just start from zeroes each time, though */
+#ifdef USE_SSL
+	memset(&lsslstatus, 0, sizeof(lsslstatus));
+#endif
+#ifdef ENABLE_GSS
+	memset(&lgssstatus, 0, sizeof(lgssstatus));
+#endif
+
+	/*
+	 * Now fill in all the fields of lbeentry, except for strings that are
+	 * out-of-line data.  Those have to be handled separately, below.
+	 */
+	lbeentry.st_procpid = MyProcPid;
+	lbeentry.st_backendType = MyBackendType;
+	lbeentry.st_proc_start_timestamp = MyStartTimestamp;
+	lbeentry.st_activity_start_timestamp = 0;
+	lbeentry.st_state_start_timestamp = 0;
+	lbeentry.st_xact_start_timestamp = 0;
+	lbeentry.st_databaseid = MyDatabaseId;
+
+	/* We have userid for client-backends, wal-sender and bgworker processes */
+	if (lbeentry.st_backendType == B_BACKEND
+		|| lbeentry.st_backendType == B_WAL_SENDER
+		|| lbeentry.st_backendType == B_BG_WORKER)
+		lbeentry.st_userid = GetSessionUserId();
+	else
+		lbeentry.st_userid = InvalidOid;
+
+	/*
+	 * We may not have a MyProcPort (eg, if this is the autovacuum process).
+	 * If so, use all-zeroes client address, which is dealt with specially in
+	 * pg_stat_get_backend_client_addr and pg_stat_get_backend_client_port.
+	 */
+	if (MyProcPort)
+		memcpy(&lbeentry.st_clientaddr, &MyProcPort->raddr,
+			   sizeof(lbeentry.st_clientaddr));
+	else
+		MemSet(&lbeentry.st_clientaddr, 0, sizeof(lbeentry.st_clientaddr));
+
+#ifdef USE_SSL
+	if (MyProcPort && MyProcPort->ssl_in_use)
+	{
+		lbeentry.st_ssl = true;
+		lsslstatus.ssl_bits = be_tls_get_cipher_bits(MyProcPort);
+		strlcpy(lsslstatus.ssl_version, be_tls_get_version(MyProcPort), NAMEDATALEN);
+		strlcpy(lsslstatus.ssl_cipher, be_tls_get_cipher(MyProcPort), NAMEDATALEN);
+		be_tls_get_peer_subject_name(MyProcPort, lsslstatus.ssl_client_dn, NAMEDATALEN);
+		be_tls_get_peer_serial(MyProcPort, lsslstatus.ssl_client_serial, NAMEDATALEN);
+		be_tls_get_peer_issuer_name(MyProcPort, lsslstatus.ssl_issuer_dn, NAMEDATALEN);
+	}
+	else
+	{
+		lbeentry.st_ssl = false;
+	}
+#else
+	lbeentry.st_ssl = false;
+#endif
+
+#ifdef ENABLE_GSS
+	if (MyProcPort && MyProcPort->gss != NULL)
+	{
+		const char *princ = be_gssapi_get_princ(MyProcPort);
+
+		lbeentry.st_gss = true;
+		lgssstatus.gss_auth = be_gssapi_get_auth(MyProcPort);
+		lgssstatus.gss_enc = be_gssapi_get_enc(MyProcPort);
+		if (princ)
+			strlcpy(lgssstatus.gss_princ, princ, NAMEDATALEN);
+	}
+	else
+	{
+		lbeentry.st_gss = false;
+	}
+#else
+	lbeentry.st_gss = false;
+#endif
+
+	lbeentry.st_state = STATE_UNDEFINED;
+	lbeentry.st_progress_command = PROGRESS_COMMAND_INVALID;
+	lbeentry.st_progress_command_target = InvalidOid;
+	lbeentry.st_query_id = UINT64CONST(0);
+
+	/*
+	 * we don't zero st_progress_param here to save cycles; nobody should
+	 * examine it until st_progress_command has been set to something other
+	 * than PROGRESS_COMMAND_INVALID
+	 */
+
+	/*
+	 * We're ready to enter the critical section that fills the shared-memory
+	 * status entry.  We follow the protocol of bumping st_changecount before
+	 * and after; and make sure it's even afterwards.  We use a volatile
+	 * pointer here to ensure the compiler doesn't try to get cute.
+	 */
+	PGSTAT_BEGIN_WRITE_ACTIVITY(vbeentry);
+
+	/* make sure we'll memcpy the same st_changecount back */
+	lbeentry.st_changecount = vbeentry->st_changecount;
+
+	memcpy(unvolatize(PgBackendStatus *, vbeentry),
+		   &lbeentry,
+		   sizeof(PgBackendStatus));
+
+	/*
+	 * We can write the out-of-line strings and structs using the pointers
+	 * that are in lbeentry; this saves some de-volatilizing messiness.
+	 */
+	lbeentry.st_appname[0] = '\0';
+	if (MyProcPort && MyProcPort->remote_hostname)
+		strlcpy(lbeentry.st_clienthostname, MyProcPort->remote_hostname,
+				NAMEDATALEN);
+	else
+		lbeentry.st_clienthostname[0] = '\0';
+	lbeentry.st_activity_raw[0] = '\0';
+	/* Also make sure the last byte in each string area is always 0 */
+	lbeentry.st_appname[NAMEDATALEN - 1] = '\0';
+	lbeentry.st_clienthostname[NAMEDATALEN - 1] = '\0';
+	lbeentry.st_activity_raw[pgstat_track_activity_query_size - 1] = '\0';
+
+#ifdef USE_SSL
+	memcpy(lbeentry.st_sslstatus, &lsslstatus, sizeof(PgBackendSSLStatus));
+#endif
+#ifdef ENABLE_GSS
+	memcpy(lbeentry.st_gssstatus, &lgssstatus, sizeof(PgBackendGSSStatus));
+#endif
+
+	PGSTAT_END_WRITE_ACTIVITY(vbeentry);
+
+	/* Update app name to current GUC setting */
+	if (application_name)
+		pgstat_report_appname(application_name);
+}
+
+/*
+ * Clear out our entry in the PgBackendStatus array.
+ */
+static void
+pgstat_beshutdown_hook(int code, Datum arg)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+
+	/*
+	 * Clear my status entry, following the protocol of bumping st_changecount
+	 * before and after.  We use a volatile pointer here to ensure the
+	 * compiler doesn't try to get cute.
+	 */
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+
+	beentry->st_procpid = 0;	/* mark invalid */
+
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+
+	/* so that functions can check if backend_status.c is up via MyBEEntry */
+	MyBEEntry = NULL;
+}
+
+/*
+ * Discard any data collected in the current transaction.  Any subsequent
+ * request will cause new snapshots to be read.
+ *
+ * This is also invoked during transaction commit or abort to discard the
+ * no-longer-wanted snapshot.
+ */
+void
+pgstat_clear_backend_activity_snapshot(void)
+{
+	/* Release memory, if any was allocated */
+	if (backendStatusSnapContext)
+	{
+		MemoryContextDelete(backendStatusSnapContext);
+		backendStatusSnapContext = NULL;
+	}
+
+	/* Reset variables */
+	localBackendStatusTable = NULL;
+	localNumBackends = 0;
+}
+
+static void
+pgstat_setup_backend_status_context(void)
+{
+	if (!backendStatusSnapContext)
+		backendStatusSnapContext = AllocSetContextCreate(TopMemoryContext,
+														 "Backend Status Snapshot",
+														 ALLOCSET_SMALL_SIZES);
+}
+
+
+/* ----------
+ * pgstat_report_activity() -
+ *
+ *	Called from tcop/postgres.c to report what the backend is actually doing
+ *	(but note cmd_str can be NULL for certain cases).
+ *
+ * All updates of the status entry follow the protocol of bumping
+ * st_changecount before and after.  We use a volatile pointer here to
+ * ensure the compiler doesn't try to get cute.
+ * ----------
+ */
+void
+pgstat_report_activity(BackendState state, const char *cmd_str)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+	TimestampTz start_timestamp;
+	TimestampTz current_timestamp;
+	int			len = 0;
+
+	TRACE_POSTGRESQL_STATEMENT_STATUS(cmd_str);
+
+	if (!beentry)
+		return;
+
+	if (!pgstat_track_activities)
+	{
+		if (beentry->st_state != STATE_DISABLED)
+		{
+			volatile PGPROC *proc = MyProc;
+
+			/*
+			 * track_activities is disabled, but we last reported a
+			 * non-disabled state.  As our final update, change the state and
+			 * clear fields we will not be updating anymore.
+			 */
+			PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+			beentry->st_state = STATE_DISABLED;
+			beentry->st_state_start_timestamp = 0;
+			beentry->st_activity_raw[0] = '\0';
+			beentry->st_activity_start_timestamp = 0;
+			/* st_xact_start_timestamp and wait_event_info are also disabled */
+			beentry->st_xact_start_timestamp = 0;
+			beentry->st_query_id = UINT64CONST(0);
+			proc->wait_event_info = 0;
+			PGSTAT_END_WRITE_ACTIVITY(beentry);
+		}
+		return;
+	}
+
+	/*
+	 * To minimize the time spent modifying the entry, and avoid risk of
+	 * errors inside the critical section, fetch all the needed data first.
+	 */
+	start_timestamp = GetCurrentStatementStartTimestamp();
+	if (cmd_str != NULL)
+	{
+		/*
+		 * Compute length of to-be-stored string unaware of multi-byte
+		 * characters. For speed reasons that'll get corrected on read, rather
+		 * than computed every write.
+		 */
+		len = Min(strlen(cmd_str), pgstat_track_activity_query_size - 1);
+	}
+	current_timestamp = GetCurrentTimestamp();
+
+	/*
+	 * If the state has changed from "active" or "idle in transaction",
+	 * calculate the duration.
+	 */
+	if ((beentry->st_state == STATE_RUNNING ||
+		 beentry->st_state == STATE_FASTPATH ||
+		 beentry->st_state == STATE_IDLEINTRANSACTION ||
+		 beentry->st_state == STATE_IDLEINTRANSACTION_ABORTED) &&
+		state != beentry->st_state)
+	{
+		long		secs;
+		int			usecs;
+
+		TimestampDifference(beentry->st_state_start_timestamp,
+							current_timestamp,
+							&secs, &usecs);
+
+		if (beentry->st_state == STATE_RUNNING ||
+			beentry->st_state == STATE_FASTPATH)
+			pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);
+		else
+			pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 + usecs);
+	}
+
+	/*
+	 * Now update the status entry
+	 */
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+
+	beentry->st_state = state;
+	beentry->st_state_start_timestamp = current_timestamp;
+
+	/*
+	 * If a new query is started, we reset the query identifier as it'll only
+	 * be known after parse analysis, to avoid reporting last query's
+	 * identifier.
+	 */
+	if (state == STATE_RUNNING)
+		beentry->st_query_id = UINT64CONST(0);
+
+	if (cmd_str != NULL)
+	{
+		memcpy((char *) beentry->st_activity_raw, cmd_str, len);
+		beentry->st_activity_raw[len] = '\0';
+		beentry->st_activity_start_timestamp = start_timestamp;
+	}
+
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
+
+/* --------
+ * pgstat_report_query_id() -
+ *
+ * Called to update top-level query identifier.
+ * --------
+ */
+void
+pgstat_report_query_id(uint64 query_id, bool force)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+
+	/*
+	 * if track_activities is disabled, st_query_id should already have been
+	 * reset
+	 */
+	if (!beentry || !pgstat_track_activities)
+		return;
+
+	/*
+	 * We only report the top-level query identifiers.  The stored query_id is
+	 * reset when a backend calls pgstat_report_activity(STATE_RUNNING), or
+	 * with an explicit call to this function using the force flag.  If the
+	 * saved query identifier is not zero it means that it's not a top-level
+	 * command, so ignore the one provided unless it's an explicit call to
+	 * reset the identifier.
+	 */
+	if (beentry->st_query_id != 0 && !force)
+		return;
+
+	/*
+	 * Update my status entry, following the protocol of bumping
+	 * st_changecount before and after.  We use a volatile pointer here to
+	 * ensure the compiler doesn't try to get cute.
+	 */
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+	beentry->st_query_id = query_id;
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
+
+
+/* ----------
+ * pgstat_report_appname() -
+ *
+ *	Called to update our application name.
+ * ----------
+ */
+void
+pgstat_report_appname(const char *appname)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+	int			len;
+
+	if (!beentry)
+		return;
+
+	/* This should be unnecessary if GUC did its job, but be safe */
+	len = pg_mbcliplen(appname, strlen(appname), NAMEDATALEN - 1);
+
+	/*
+	 * Update my status entry, following the protocol of bumping
+	 * st_changecount before and after.  We use a volatile pointer here to
+	 * ensure the compiler doesn't try to get cute.
+	 */
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+
+	memcpy((char *) beentry->st_appname, appname, len);
+	beentry->st_appname[len] = '\0';
+
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
+
+/*
+ * Report current transaction start timestamp as the specified value.
+ * Zero means there is no active transaction.
+ */
+void
+pgstat_report_xact_timestamp(TimestampTz tstamp)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+
+	if (!pgstat_track_activities || !beentry)
+		return;
+
+	/*
+	 * Update my status entry, following the protocol of bumping
+	 * st_changecount before and after.  We use a volatile pointer here to
+	 * ensure the compiler doesn't try to get cute.
+	 */
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+
+	beentry->st_xact_start_timestamp = tstamp;
+
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
+
+/* ----------
+ * pgstat_read_current_status() -
+ *
+ *	Copy the current contents of the PgBackendStatus array to local memory,
+ *	if not already done in this transaction.
+ * ----------
+ */
+static void
+pgstat_read_current_status(void)
+{
+	volatile PgBackendStatus *beentry;
+	LocalPgBackendStatus *localtable;
+	LocalPgBackendStatus *localentry;
+	char	   *localappname,
+			   *localclienthostname,
+			   *localactivity;
+#ifdef USE_SSL
+	PgBackendSSLStatus *localsslstatus;
+#endif
+#ifdef ENABLE_GSS
+	PgBackendGSSStatus *localgssstatus;
+#endif
+	int			i;
+
+	if (localBackendStatusTable)
+		return;					/* already done */
+
+	pgstat_setup_backend_status_context();
+
+	/*
+	 * Allocate storage for local copy of state data.  We can presume that
+	 * none of these requests overflow size_t, because we already calculated
+	 * the same values using mul_size during shmem setup.  However, with
+	 * probably-silly values of pgstat_track_activity_query_size and
+	 * max_connections, the localactivity buffer could exceed 1GB, so use
+	 * "huge" allocation for that one.
+	 */
+	localtable = (LocalPgBackendStatus *)
+		MemoryContextAlloc(backendStatusSnapContext,
+						   sizeof(LocalPgBackendStatus) * NumBackendStatSlots);
+	localappname = (char *)
+		MemoryContextAlloc(backendStatusSnapContext,
+						   NAMEDATALEN * NumBackendStatSlots);
+	localclienthostname = (char *)
+		MemoryContextAlloc(backendStatusSnapContext,
+						   NAMEDATALEN * NumBackendStatSlots);
+	localactivity = (char *)
+		MemoryContextAllocHuge(backendStatusSnapContext,
+							   pgstat_track_activity_query_size * NumBackendStatSlots);
+#ifdef USE_SSL
+	localsslstatus = (PgBackendSSLStatus *)
+		MemoryContextAlloc(backendStatusSnapContext,
+						   sizeof(PgBackendSSLStatus) * NumBackendStatSlots);
+#endif
+#ifdef ENABLE_GSS
+	localgssstatus = (PgBackendGSSStatus *)
+		MemoryContextAlloc(backendStatusSnapContext,
+						   sizeof(PgBackendGSSStatus) * NumBackendStatSlots);
+#endif
+
+	localNumBackends = 0;
+
+	beentry = BackendStatusArray;
+	localentry = localtable;
+	for (i = 1; i <= NumBackendStatSlots; i++)
+	{
+		/*
+		 * Follow the protocol of retrying if st_changecount changes while we
+		 * copy the entry, or if it's odd.  (The check for odd is needed to
+		 * cover the case where we are able to completely copy the entry while
+		 * the source backend is between increment steps.)	We use a volatile
+		 * pointer here to ensure the compiler doesn't try to get cute.
+		 */
+		for (;;)
+		{
+			int			before_changecount;
+			int			after_changecount;
+
+			pgstat_begin_read_activity(beentry, before_changecount);
+
+			localentry->backendStatus.st_procpid = beentry->st_procpid;
+			/* Skip all the data-copying work if entry is not in use */
+			if (localentry->backendStatus.st_procpid > 0)
+			{
+				memcpy(&localentry->backendStatus, unvolatize(PgBackendStatus *, beentry), sizeof(PgBackendStatus));
+
+				/*
+				 * For each PgBackendStatus field that is a pointer, copy the
+				 * pointed-to data, then adjust the local copy of the pointer
+				 * field to point at the local copy of the data.
+				 *
+				 * strcpy is safe even if the string is modified concurrently,
+				 * because there's always a \0 at the end of the buffer.
+				 */
+				strcpy(localappname, (char *) beentry->st_appname);
+				localentry->backendStatus.st_appname = localappname;
+				strcpy(localclienthostname, (char *) beentry->st_clienthostname);
+				localentry->backendStatus.st_clienthostname = localclienthostname;
+				strcpy(localactivity, (char *) beentry->st_activity_raw);
+				localentry->backendStatus.st_activity_raw = localactivity;
+#ifdef USE_SSL
+				if (beentry->st_ssl)
+				{
+					memcpy(localsslstatus, beentry->st_sslstatus, sizeof(PgBackendSSLStatus));
+					localentry->backendStatus.st_sslstatus = localsslstatus;
+				}
+#endif
+#ifdef ENABLE_GSS
+				if (beentry->st_gss)
+				{
+					memcpy(localgssstatus, beentry->st_gssstatus, sizeof(PgBackendGSSStatus));
+					localentry->backendStatus.st_gssstatus = localgssstatus;
+				}
+#endif
+			}
+
+			pgstat_end_read_activity(beentry, after_changecount);
+
+			if (pgstat_read_activity_complete(before_changecount,
+											  after_changecount))
+				break;
+
+			/* Make sure we can break out of loop if stuck... */
+			CHECK_FOR_INTERRUPTS();
+		}
+
+		beentry++;
+		/* Only valid entries get included into the local array */
+		if (localentry->backendStatus.st_procpid > 0)
+		{
+			BackendIdGetTransactionIds(i,
+									   &localentry->backend_xid,
+									   &localentry->backend_xmin);
+
+			localentry++;
+			localappname += NAMEDATALEN;
+			localclienthostname += NAMEDATALEN;
+			localactivity += pgstat_track_activity_query_size;
+#ifdef USE_SSL
+			localsslstatus++;
+#endif
+#ifdef ENABLE_GSS
+			localgssstatus++;
+#endif
+			localNumBackends++;
+		}
+	}
+
+	/* Set the pointer only after completion of a valid table */
+	localBackendStatusTable = localtable;
+}
+
+
+/* ----------
+ * pgstat_get_backend_current_activity() -
+ *
+ *	Return a string representing the current activity of the backend with
+ *	the specified PID.  This looks directly at the BackendStatusArray,
+ *	and so will provide current information regardless of the age of our
+ *	transaction's snapshot of the status array.
+ *
+ *	It is the caller's responsibility to invoke this only for backends whose
+ *	state is expected to remain stable while the result is in use.  The
+ *	only current use is in deadlock reporting, where we can expect that
+ *	the target backend is blocked on a lock.  (There are corner cases
+ *	where the target's wait could get aborted while we are looking at it,
+ *	but the very worst consequence is to return a pointer to a string
+ *	that's been changed, so we won't worry too much.)
+ *
+ *	Note: return strings for special cases match pg_stat_get_backend_activity.
+ * ----------
+ */
+const char *
+pgstat_get_backend_current_activity(int pid, bool checkUser)
+{
+	PgBackendStatus *beentry;
+	int			i;
+
+	beentry = BackendStatusArray;
+	for (i = 1; i <= MaxBackends; i++)
+	{
+		/*
+		 * Although we expect the target backend's entry to be stable, that
+		 * doesn't imply that anyone else's is.  To avoid identifying the
+		 * wrong backend, while we check for a match to the desired PID we
+		 * must follow the protocol of retrying if st_changecount changes
+		 * while we examine the entry, or if it's odd.  (This might be
+		 * unnecessary, since fetching or storing an int is almost certainly
+		 * atomic, but let's play it safe.)  We use a volatile pointer here to
+		 * ensure the compiler doesn't try to get cute.
+		 */
+		volatile PgBackendStatus *vbeentry = beentry;
+		bool		found;
+
+		for (;;)
+		{
+			int			before_changecount;
+			int			after_changecount;
+
+			pgstat_begin_read_activity(vbeentry, before_changecount);
+
+			found = (vbeentry->st_procpid == pid);
+
+			pgstat_end_read_activity(vbeentry, after_changecount);
+
+			if (pgstat_read_activity_complete(before_changecount,
+											  after_changecount))
+				break;
+
+			/* Make sure we can break out of loop if stuck... */
+			CHECK_FOR_INTERRUPTS();
+		}
+
+		if (found)
+		{
+			/* Now it is safe to use the non-volatile pointer */
+			if (checkUser && !superuser() && beentry->st_userid != GetUserId())
+				return "<insufficient privilege>";
+			else if (*(beentry->st_activity_raw) == '\0')
+				return "<command string not enabled>";
+			else
+			{
+				/* this'll leak a bit of memory, but that seems acceptable */
+				return pgstat_clip_activity(beentry->st_activity_raw);
+			}
+		}
+
+		beentry++;
+	}
+
+	/* If we get here, caller is in error ... */
+	return "<backend information not available>";
+}
+
+/* ----------
+ * pgstat_get_crashed_backend_activity() -
+ *
+ *	Return a string representing the current activity of the backend with
+ *	the specified PID.  Like the function above, but reads shared memory with
+ *	the expectation that it may be corrupt.  On success, copy the string
+ *	into the "buffer" argument and return that pointer.  On failure,
+ *	return NULL.
+ *
+ *	This function is only intended to be used by the postmaster to report the
+ *	query that crashed a backend.  In particular, no attempt is made to
+ *	follow the correct concurrency protocol when accessing the
+ *	BackendStatusArray.  But that's OK, in the worst case we'll return a
+ *	corrupted message.  We also must take care not to trip on ereport(ERROR).
+ * ----------
+ */
+const char *
+pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
+{
+	volatile PgBackendStatus *beentry;
+	int			i;
+
+	beentry = BackendStatusArray;
+
+	/*
+	 * We probably shouldn't get here before shared memory has been set up,
+	 * but be safe.
+	 */
+	if (beentry == NULL || BackendActivityBuffer == NULL)
+		return NULL;
+
+	for (i = 1; i <= MaxBackends; i++)
+	{
+		if (beentry->st_procpid == pid)
+		{
+			/* Read pointer just once, so it can't change after validation */
+			const char *activity = beentry->st_activity_raw;
+			const char *activity_last;
+
+			/*
+			 * We mustn't access activity string before we verify that it
+			 * falls within the BackendActivityBuffer. To make sure that the
+			 * entire string including its ending is contained within the
+			 * buffer, subtract one activity length from the buffer size.
+			 */
+			activity_last = BackendActivityBuffer + BackendActivityBufferSize
+				- pgstat_track_activity_query_size;
+
+			if (activity < BackendActivityBuffer ||
+				activity > activity_last)
+				return NULL;
+
+			/* If no string available, no point in a report */
+			if (activity[0] == '\0')
+				return NULL;
+
+			/*
+			 * Copy only ASCII-safe characters so we don't run into encoding
+			 * problems when reporting the message; and be sure not to run off
+			 * the end of memory.  As only ASCII characters are reported, it
+			 * doesn't seem necessary to perform multibyte aware clipping.
+			 */
+			ascii_safe_strlcpy(buffer, activity,
+							   Min(buflen, pgstat_track_activity_query_size));
+
+			return buffer;
+		}
+
+		beentry++;
+	}
+
+	/* PID not found */
+	return NULL;
+}
+
+/* ----------
+ * pgstat_get_my_query_id() -
+ *
+ * Return current backend's query identifier.
+ */
+uint64
+pgstat_get_my_query_id(void)
+{
+	if (!MyBEEntry)
+		return 0;
+
+	/*
+	 * There's no need for a lock around pgstat_begin_read_activity /
+	 * pgstat_end_read_activity here as it's only called from
+	 * pg_stat_get_activity which is already protected, or from the same
+	 * backend which means that there won't be concurrent writes.
+	 */
+	return MyBEEntry->st_query_id;
+}
+
+
+/* ----------
+ * pgstat_fetch_stat_beentry() -
+ *
+ *	Support function for the SQL-callable pgstat* functions. Returns
+ *	our local copy of the current-activity entry for one backend.
+ *
+ *	NB: caller is responsible for a check if the user is permitted to see
+ *	this info (especially the querystring).
+ * ----------
+ */
+PgBackendStatus *
+pgstat_fetch_stat_beentry(int beid)
+{
+	pgstat_read_current_status();
+
+	if (beid < 1 || beid > localNumBackends)
+		return NULL;
+
+	return &localBackendStatusTable[beid - 1].backendStatus;
+}
+
+
+/* ----------
+ * pgstat_fetch_stat_local_beentry() -
+ *
+ *	Like pgstat_fetch_stat_beentry() but with locally computed additions (like
+ *	xid and xmin values of the backend)
+ *
+ *	NB: caller is responsible for a check if the user is permitted to see
+ *	this info (especially the querystring).
+ * ----------
+ */
+LocalPgBackendStatus *
+pgstat_fetch_stat_local_beentry(int beid)
+{
+	pgstat_read_current_status();
+
+	if (beid < 1 || beid > localNumBackends)
+		return NULL;
+
+	return &localBackendStatusTable[beid - 1];
+}
+
+
+/* ----------
+ * pgstat_fetch_stat_numbackends() -
+ *
+ *	Support function for the SQL-callable pgstat* functions. Returns
+ *	the maximum current backend id.
+ * ----------
+ */
+int
+pgstat_fetch_stat_numbackends(void)
+{
+	pgstat_read_current_status();
+
+	return localNumBackends;
+}
+
+/*
+ * Convert a potentially unsafely truncated activity string (see
+ * PgBackendStatus.st_activity_raw's documentation) into a correctly truncated
+ * one.
+ *
+ * The returned string is allocated in the caller's memory context and may be
+ * freed.
+ */
+char *
+pgstat_clip_activity(const char *raw_activity)
+{
+	char	   *activity;
+	int			rawlen;
+	int			cliplen;
+
+	/*
+	 * Some callers, like pgstat_get_backend_current_activity(), do not
+	 * guarantee that the buffer isn't concurrently modified. We try to take
+	 * care that the buffer is always terminated by a NUL byte regardless, but
+	 * let's still be paranoid about the string's length. In those cases the
+	 * underlying buffer is guaranteed to be pgstat_track_activity_query_size
+	 * large.
+	 */
+	activity = pnstrdup(raw_activity, pgstat_track_activity_query_size - 1);
+
+	/* now double-guaranteed to be NUL terminated */
+	rawlen = strlen(activity);
+
+	/*
+	 * All supported server-encodings make it possible to determine the length
+	 * of a multi-byte character from its first byte (this is not the case for
+	 * client encodings, see GB18030). As st_activity is always stored using
+	 * server encoding, this allows us to perform multi-byte aware truncation,
+	 * even if the string earlier was truncated in the middle of a multi-byte
+	 * character.
+	 */
+	cliplen = pg_mbcliplen(activity, rawlen,
+						   pgstat_track_activity_query_size - 1);
+
+	activity[cliplen] = '\0';
+
+	return activity;
+}
diff --git a/src/backend/utils/activity/wait_event.c b/src/backend/utils/activity/wait_event.c
new file mode 100644
index 0000000..1a30faf
--- /dev/null
+++ b/src/backend/utils/activity/wait_event.c
@@ -0,0 +1,740 @@
+/* ----------
+ * wait_event.c
+ *	  Wait event reporting infrastructure.
+ *
+ * Copyright (c) 2001-2021, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/postmaster/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_PGSTAT_MAIN:
+			event_name = "PgStatMain";
+			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_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_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_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;
+			/* 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_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_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;
+		case WAIT_EVENT_LOGICAL_CHANGES_READ:
+			event_name = "LogicalChangesRead";
+			break;
+		case WAIT_EVENT_LOGICAL_CHANGES_WRITE:
+			event_name = "LogicalChangesWrite";
+			break;
+		case WAIT_EVENT_LOGICAL_SUBXACT_READ:
+			event_name = "LogicalSubxactRead";
+			break;
+		case WAIT_EVENT_LOGICAL_SUBXACT_WRITE:
+			event_name = "LogicalSubxactWrite";
+			break;
+
+			/* no default case, so that compiler will warn */
+	}
+
+	return event_name;
+}