Split wait event related code from pgstat.[ch] into wait_event.[ch].

The wait event related code is independent from the rest of the
pgstat.[ch] code, of nontrivial size and changes on a regular
basis. Put it into its own set of files.

As there doesn't seem to be a good pre-existing directory for code
like this, add src/backend/utils/activity.

Reviewed-By: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/20210316195440.twxmlov24rr2nxrg@alap3.anarazel.de

2 files changed, 302 insertions, 273 deletions

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index fe6683cf5c8..3247c7b8ad0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -17,9 +17,9 @@
 #include "port/atomics.h"
 #include "portability/instr_time.h"
 #include "postmaster/pgarch.h"
-#include "storage/proc.h"
 #include "utils/hsearch.h"
 #include "utils/relcache.h"
+#include "utils/wait_event.h" /* for backward compatibility */
 
 
 /* ----------
@@ -897,222 +897,6 @@ typedef enum BackendState
 	STATE_DISABLED
 } BackendState;
 
-
-/* ----------
- * Wait Classes
- * ----------
- */
-#define PG_WAIT_LWLOCK				0x01000000U
-#define PG_WAIT_LOCK				0x03000000U
-#define PG_WAIT_BUFFER_PIN			0x04000000U
-#define PG_WAIT_ACTIVITY			0x05000000U
-#define PG_WAIT_CLIENT				0x06000000U
-#define PG_WAIT_EXTENSION			0x07000000U
-#define PG_WAIT_IPC					0x08000000U
-#define PG_WAIT_TIMEOUT				0x09000000U
-#define PG_WAIT_IO					0x0A000000U
-
-/* ----------
- * Wait Events - Activity
- *
- * Use this category when a process is waiting because it has no work to do,
- * unless the "Client" or "Timeout" category describes the situation better.
- * Typically, this should only be used for background processes.
- * ----------
- */
-typedef enum
-{
-	WAIT_EVENT_ARCHIVER_MAIN = PG_WAIT_ACTIVITY,
-	WAIT_EVENT_AUTOVACUUM_MAIN,
-	WAIT_EVENT_BGWRITER_HIBERNATE,
-	WAIT_EVENT_BGWRITER_MAIN,
-	WAIT_EVENT_CHECKPOINTER_MAIN,
-	WAIT_EVENT_LOGICAL_APPLY_MAIN,
-	WAIT_EVENT_LOGICAL_LAUNCHER_MAIN,
-	WAIT_EVENT_PGSTAT_MAIN,
-	WAIT_EVENT_RECOVERY_WAL_STREAM,
-	WAIT_EVENT_SYSLOGGER_MAIN,
-	WAIT_EVENT_WAL_RECEIVER_MAIN,
-	WAIT_EVENT_WAL_SENDER_MAIN,
-	WAIT_EVENT_WAL_WRITER_MAIN
-} WaitEventActivity;
-
-/* ----------
- * Wait Events - Client
- *
- * Use this category when a process is waiting to send data to or receive data
- * from the frontend process to which it is connected.  This is never used for
- * a background process, which has no client connection.
- * ----------
- */
-typedef enum
-{
-	WAIT_EVENT_CLIENT_READ = PG_WAIT_CLIENT,
-	WAIT_EVENT_CLIENT_WRITE,
-	WAIT_EVENT_GSS_OPEN_SERVER,
-	WAIT_EVENT_LIBPQWALRECEIVER_CONNECT,
-	WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE,
-	WAIT_EVENT_SSL_OPEN_SERVER,
-	WAIT_EVENT_WAL_SENDER_WAIT_WAL,
-	WAIT_EVENT_WAL_SENDER_WRITE_DATA,
-} WaitEventClient;
-
-/* ----------
- * Wait Events - IPC
- *
- * Use this category when a process cannot complete the work it is doing because
- * it is waiting for a notification from another process.
- * ----------
- */
-typedef enum
-{
-	WAIT_EVENT_APPEND_READY = PG_WAIT_IPC,
-	WAIT_EVENT_BACKUP_WAIT_WAL_ARCHIVE,
-	WAIT_EVENT_BGWORKER_SHUTDOWN,
-	WAIT_EVENT_BGWORKER_STARTUP,
-	WAIT_EVENT_BTREE_PAGE,
-	WAIT_EVENT_BUFFER_IO,
-	WAIT_EVENT_CHECKPOINT_DONE,
-	WAIT_EVENT_CHECKPOINT_START,
-	WAIT_EVENT_EXECUTE_GATHER,
-	WAIT_EVENT_HASH_BATCH_ALLOCATE,
-	WAIT_EVENT_HASH_BATCH_ELECT,
-	WAIT_EVENT_HASH_BATCH_LOAD,
-	WAIT_EVENT_HASH_BUILD_ALLOCATE,
-	WAIT_EVENT_HASH_BUILD_ELECT,
-	WAIT_EVENT_HASH_BUILD_HASH_INNER,
-	WAIT_EVENT_HASH_BUILD_HASH_OUTER,
-	WAIT_EVENT_HASH_GROW_BATCHES_ALLOCATE,
-	WAIT_EVENT_HASH_GROW_BATCHES_DECIDE,
-	WAIT_EVENT_HASH_GROW_BATCHES_ELECT,
-	WAIT_EVENT_HASH_GROW_BATCHES_FINISH,
-	WAIT_EVENT_HASH_GROW_BATCHES_REPARTITION,
-	WAIT_EVENT_HASH_GROW_BUCKETS_ALLOCATE,
-	WAIT_EVENT_HASH_GROW_BUCKETS_ELECT,
-	WAIT_EVENT_HASH_GROW_BUCKETS_REINSERT,
-	WAIT_EVENT_LOGICAL_SYNC_DATA,
-	WAIT_EVENT_LOGICAL_SYNC_STATE_CHANGE,
-	WAIT_EVENT_MQ_INTERNAL,
-	WAIT_EVENT_MQ_PUT_MESSAGE,
-	WAIT_EVENT_MQ_RECEIVE,
-	WAIT_EVENT_MQ_SEND,
-	WAIT_EVENT_PARALLEL_BITMAP_SCAN,
-	WAIT_EVENT_PARALLEL_CREATE_INDEX_SCAN,
-	WAIT_EVENT_PARALLEL_FINISH,
-	WAIT_EVENT_PROCARRAY_GROUP_UPDATE,
-	WAIT_EVENT_PROC_SIGNAL_BARRIER,
-	WAIT_EVENT_PROMOTE,
-	WAIT_EVENT_RECOVERY_CONFLICT_SNAPSHOT,
-	WAIT_EVENT_RECOVERY_CONFLICT_TABLESPACE,
-	WAIT_EVENT_RECOVERY_PAUSE,
-	WAIT_EVENT_REPLICATION_ORIGIN_DROP,
-	WAIT_EVENT_REPLICATION_SLOT_DROP,
-	WAIT_EVENT_SAFE_SNAPSHOT,
-	WAIT_EVENT_SYNC_REP,
-	WAIT_EVENT_WAL_RECEIVER_EXIT,
-	WAIT_EVENT_WAL_RECEIVER_WAIT_START,
-	WAIT_EVENT_XACT_GROUP_UPDATE
-} WaitEventIPC;
-
-/* ----------
- * Wait Events - Timeout
- *
- * Use this category when a process is waiting for a timeout to expire.
- * ----------
- */
-typedef enum
-{
-	WAIT_EVENT_BASE_BACKUP_THROTTLE = PG_WAIT_TIMEOUT,
-	WAIT_EVENT_PG_SLEEP,
-	WAIT_EVENT_RECOVERY_APPLY_DELAY,
-	WAIT_EVENT_RECOVERY_RETRIEVE_RETRY_INTERVAL,
-	WAIT_EVENT_VACUUM_DELAY
-} WaitEventTimeout;
-
-/* ----------
- * Wait Events - IO
- *
- * Use this category when a process is waiting for a IO.
- * ----------
- */
-typedef enum
-{
-	WAIT_EVENT_BASEBACKUP_READ = PG_WAIT_IO,
-	WAIT_EVENT_BUFFILE_READ,
-	WAIT_EVENT_BUFFILE_WRITE,
-	WAIT_EVENT_BUFFILE_TRUNCATE,
-	WAIT_EVENT_CONTROL_FILE_READ,
-	WAIT_EVENT_CONTROL_FILE_SYNC,
-	WAIT_EVENT_CONTROL_FILE_SYNC_UPDATE,
-	WAIT_EVENT_CONTROL_FILE_WRITE,
-	WAIT_EVENT_CONTROL_FILE_WRITE_UPDATE,
-	WAIT_EVENT_COPY_FILE_READ,
-	WAIT_EVENT_COPY_FILE_WRITE,
-	WAIT_EVENT_DATA_FILE_EXTEND,
-	WAIT_EVENT_DATA_FILE_FLUSH,
-	WAIT_EVENT_DATA_FILE_IMMEDIATE_SYNC,
-	WAIT_EVENT_DATA_FILE_PREFETCH,
-	WAIT_EVENT_DATA_FILE_READ,
-	WAIT_EVENT_DATA_FILE_SYNC,
-	WAIT_EVENT_DATA_FILE_TRUNCATE,
-	WAIT_EVENT_DATA_FILE_WRITE,
-	WAIT_EVENT_DSM_FILL_ZERO_WRITE,
-	WAIT_EVENT_LOCK_FILE_ADDTODATADIR_READ,
-	WAIT_EVENT_LOCK_FILE_ADDTODATADIR_SYNC,
-	WAIT_EVENT_LOCK_FILE_ADDTODATADIR_WRITE,
-	WAIT_EVENT_LOCK_FILE_CREATE_READ,
-	WAIT_EVENT_LOCK_FILE_CREATE_SYNC,
-	WAIT_EVENT_LOCK_FILE_CREATE_WRITE,
-	WAIT_EVENT_LOCK_FILE_RECHECKDATADIR_READ,
-	WAIT_EVENT_LOGICAL_REWRITE_CHECKPOINT_SYNC,
-	WAIT_EVENT_LOGICAL_REWRITE_MAPPING_SYNC,
-	WAIT_EVENT_LOGICAL_REWRITE_MAPPING_WRITE,
-	WAIT_EVENT_LOGICAL_REWRITE_SYNC,
-	WAIT_EVENT_LOGICAL_REWRITE_TRUNCATE,
-	WAIT_EVENT_LOGICAL_REWRITE_WRITE,
-	WAIT_EVENT_RELATION_MAP_READ,
-	WAIT_EVENT_RELATION_MAP_SYNC,
-	WAIT_EVENT_RELATION_MAP_WRITE,
-	WAIT_EVENT_REORDER_BUFFER_READ,
-	WAIT_EVENT_REORDER_BUFFER_WRITE,
-	WAIT_EVENT_REORDER_LOGICAL_MAPPING_READ,
-	WAIT_EVENT_REPLICATION_SLOT_READ,
-	WAIT_EVENT_REPLICATION_SLOT_RESTORE_SYNC,
-	WAIT_EVENT_REPLICATION_SLOT_SYNC,
-	WAIT_EVENT_REPLICATION_SLOT_WRITE,
-	WAIT_EVENT_SLRU_FLUSH_SYNC,
-	WAIT_EVENT_SLRU_READ,
-	WAIT_EVENT_SLRU_SYNC,
-	WAIT_EVENT_SLRU_WRITE,
-	WAIT_EVENT_SNAPBUILD_READ,
-	WAIT_EVENT_SNAPBUILD_SYNC,
-	WAIT_EVENT_SNAPBUILD_WRITE,
-	WAIT_EVENT_TIMELINE_HISTORY_FILE_SYNC,
-	WAIT_EVENT_TIMELINE_HISTORY_FILE_WRITE,
-	WAIT_EVENT_TIMELINE_HISTORY_READ,
-	WAIT_EVENT_TIMELINE_HISTORY_SYNC,
-	WAIT_EVENT_TIMELINE_HISTORY_WRITE,
-	WAIT_EVENT_TWOPHASE_FILE_READ,
-	WAIT_EVENT_TWOPHASE_FILE_SYNC,
-	WAIT_EVENT_TWOPHASE_FILE_WRITE,
-	WAIT_EVENT_WALSENDER_TIMELINE_HISTORY_READ,
-	WAIT_EVENT_WAL_BOOTSTRAP_SYNC,
-	WAIT_EVENT_WAL_BOOTSTRAP_WRITE,
-	WAIT_EVENT_WAL_COPY_READ,
-	WAIT_EVENT_WAL_COPY_SYNC,
-	WAIT_EVENT_WAL_COPY_WRITE,
-	WAIT_EVENT_WAL_INIT_SYNC,
-	WAIT_EVENT_WAL_INIT_WRITE,
-	WAIT_EVENT_WAL_READ,
-	WAIT_EVENT_WAL_SYNC,
-	WAIT_EVENT_WAL_SYNC_METHOD_ASSIGN,
-	WAIT_EVENT_WAL_WRITE,
-	WAIT_EVENT_LOGICAL_CHANGES_READ,
-	WAIT_EVENT_LOGICAL_CHANGES_WRITE,
-	WAIT_EVENT_LOGICAL_SUBXACT_READ,
-	WAIT_EVENT_LOGICAL_SUBXACT_WRITE
-} WaitEventIO;
-
 /* ----------
  * Command type for progress reporting purposes
  * ----------
@@ -1463,8 +1247,6 @@ extern void pgstat_report_activity(BackendState state, const char *cmd_str);
 extern void pgstat_report_tempfile(size_t filesize);
 extern void pgstat_report_appname(const char *appname);
 extern void pgstat_report_xact_timestamp(TimestampTz tstamp);
-extern const char *pgstat_get_wait_event(uint32 wait_event_info);
-extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
 													   int buflen);
@@ -1483,60 +1265,6 @@ extern void pgstat_initstats(Relation rel);
 
 extern char *pgstat_clip_activity(const char *raw_activity);
 
-/* ----------
- * pgstat_report_wait_start() -
- *
- *	Called from places where server process needs to wait.  This is called
- *	to report wait event information.  The wait information is stored
- *	as 4-bytes where first byte represents the wait event class (type of
- *	wait, for different types of wait, refer WaitClass) and the next
- *	3-bytes represent the actual wait event.  Currently 2-bytes are used
- *	for wait event which is sufficient for current usage, 1-byte is
- *	reserved for future usage.
- *
- * NB: this *must* be able to survive being called before MyProc has been
- * initialized.
- * ----------
- */
-static inline void
-pgstat_report_wait_start(uint32 wait_event_info)
-{
-	volatile PGPROC *proc = MyProc;
-
-	if (!pgstat_track_activities || !proc)
-		return;
-
-	/*
-	 * Since this is a four-byte field which is always read and written as
-	 * four-bytes, updates are atomic.
-	 */
-	proc->wait_event_info = wait_event_info;
-}
-
-/* ----------
- * pgstat_report_wait_end() -
- *
- *	Called to report end of a wait.
- *
- * NB: this *must* be able to survive being called before MyProc has been
- * initialized.
- * ----------
- */
-static inline void
-pgstat_report_wait_end(void)
-{
-	volatile PGPROC *proc = MyProc;
-
-	if (!pgstat_track_activities || !proc)
-		return;
-
-	/*
-	 * Since this is a four-byte field which is always read and written as
-	 * four-bytes, updates are atomic.
-	 */
-	proc->wait_event_info = 0;
-}
-
 /* nontransactional event counts are simple enough to inline */
 
 #define pgstat_count_heap_scan(rel)									\
diff --git a/src/include/utils/wait_event.h b/src/include/utils/wait_event.h
new file mode 100644
index 00000000000..2c883467f34
--- /dev/null
+++ b/src/include/utils/wait_event.h
@@ -0,0 +1,301 @@
+/*-------------------------------------------------------------------------
+ * wait_event.h
+ *	  Definitions related to wait event reporting
+ *
+ * Copyright (c) 2001-2021, PostgreSQL Global Development Group
+ *
+ * src/include/utils/wait_event.h
+ * ----------
+ */
+#ifndef WAIT_EVENT_H
+#define WAIT_EVENT_H
+
+
+#include "storage/proc.h" /* for MyProc */
+
+
+/* ----------
+ * Wait Classes
+ * ----------
+ */
+#define PG_WAIT_LWLOCK				0x01000000U
+#define PG_WAIT_LOCK				0x03000000U
+#define PG_WAIT_BUFFER_PIN			0x04000000U
+#define PG_WAIT_ACTIVITY			0x05000000U
+#define PG_WAIT_CLIENT				0x06000000U
+#define PG_WAIT_EXTENSION			0x07000000U
+#define PG_WAIT_IPC					0x08000000U
+#define PG_WAIT_TIMEOUT				0x09000000U
+#define PG_WAIT_IO					0x0A000000U
+
+/* ----------
+ * Wait Events - Activity
+ *
+ * Use this category when a process is waiting because it has no work to do,
+ * unless the "Client" or "Timeout" category describes the situation better.
+ * Typically, this should only be used for background processes.
+ * ----------
+ */
+typedef enum
+{
+	WAIT_EVENT_ARCHIVER_MAIN = PG_WAIT_ACTIVITY,
+	WAIT_EVENT_AUTOVACUUM_MAIN,
+	WAIT_EVENT_BGWRITER_HIBERNATE,
+	WAIT_EVENT_BGWRITER_MAIN,
+	WAIT_EVENT_CHECKPOINTER_MAIN,
+	WAIT_EVENT_LOGICAL_APPLY_MAIN,
+	WAIT_EVENT_LOGICAL_LAUNCHER_MAIN,
+	WAIT_EVENT_PGSTAT_MAIN,
+	WAIT_EVENT_RECOVERY_WAL_STREAM,
+	WAIT_EVENT_SYSLOGGER_MAIN,
+	WAIT_EVENT_WAL_RECEIVER_MAIN,
+	WAIT_EVENT_WAL_SENDER_MAIN,
+	WAIT_EVENT_WAL_WRITER_MAIN
+} WaitEventActivity;
+
+/* ----------
+ * Wait Events - Client
+ *
+ * Use this category when a process is waiting to send data to or receive data
+ * from the frontend process to which it is connected.  This is never used for
+ * a background process, which has no client connection.
+ * ----------
+ */
+typedef enum
+{
+	WAIT_EVENT_CLIENT_READ = PG_WAIT_CLIENT,
+	WAIT_EVENT_CLIENT_WRITE,
+	WAIT_EVENT_GSS_OPEN_SERVER,
+	WAIT_EVENT_LIBPQWALRECEIVER_CONNECT,
+	WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE,
+	WAIT_EVENT_SSL_OPEN_SERVER,
+	WAIT_EVENT_WAL_SENDER_WAIT_WAL,
+	WAIT_EVENT_WAL_SENDER_WRITE_DATA,
+} WaitEventClient;
+
+/* ----------
+ * Wait Events - IPC
+ *
+ * Use this category when a process cannot complete the work it is doing because
+ * it is waiting for a notification from another process.
+ * ----------
+ */
+typedef enum
+{
+	WAIT_EVENT_APPEND_READY = PG_WAIT_IPC,
+	WAIT_EVENT_BACKUP_WAIT_WAL_ARCHIVE,
+	WAIT_EVENT_BGWORKER_SHUTDOWN,
+	WAIT_EVENT_BGWORKER_STARTUP,
+	WAIT_EVENT_BTREE_PAGE,
+	WAIT_EVENT_BUFFER_IO,
+	WAIT_EVENT_CHECKPOINT_DONE,
+	WAIT_EVENT_CHECKPOINT_START,
+	WAIT_EVENT_EXECUTE_GATHER,
+	WAIT_EVENT_HASH_BATCH_ALLOCATE,
+	WAIT_EVENT_HASH_BATCH_ELECT,
+	WAIT_EVENT_HASH_BATCH_LOAD,
+	WAIT_EVENT_HASH_BUILD_ALLOCATE,
+	WAIT_EVENT_HASH_BUILD_ELECT,
+	WAIT_EVENT_HASH_BUILD_HASH_INNER,
+	WAIT_EVENT_HASH_BUILD_HASH_OUTER,
+	WAIT_EVENT_HASH_GROW_BATCHES_ALLOCATE,
+	WAIT_EVENT_HASH_GROW_BATCHES_DECIDE,
+	WAIT_EVENT_HASH_GROW_BATCHES_ELECT,
+	WAIT_EVENT_HASH_GROW_BATCHES_FINISH,
+	WAIT_EVENT_HASH_GROW_BATCHES_REPARTITION,
+	WAIT_EVENT_HASH_GROW_BUCKETS_ALLOCATE,
+	WAIT_EVENT_HASH_GROW_BUCKETS_ELECT,
+	WAIT_EVENT_HASH_GROW_BUCKETS_REINSERT,
+	WAIT_EVENT_LOGICAL_SYNC_DATA,
+	WAIT_EVENT_LOGICAL_SYNC_STATE_CHANGE,
+	WAIT_EVENT_MQ_INTERNAL,
+	WAIT_EVENT_MQ_PUT_MESSAGE,
+	WAIT_EVENT_MQ_RECEIVE,
+	WAIT_EVENT_MQ_SEND,
+	WAIT_EVENT_PARALLEL_BITMAP_SCAN,
+	WAIT_EVENT_PARALLEL_CREATE_INDEX_SCAN,
+	WAIT_EVENT_PARALLEL_FINISH,
+	WAIT_EVENT_PROCARRAY_GROUP_UPDATE,
+	WAIT_EVENT_PROC_SIGNAL_BARRIER,
+	WAIT_EVENT_PROMOTE,
+	WAIT_EVENT_RECOVERY_CONFLICT_SNAPSHOT,
+	WAIT_EVENT_RECOVERY_CONFLICT_TABLESPACE,
+	WAIT_EVENT_RECOVERY_PAUSE,
+	WAIT_EVENT_REPLICATION_ORIGIN_DROP,
+	WAIT_EVENT_REPLICATION_SLOT_DROP,
+	WAIT_EVENT_SAFE_SNAPSHOT,
+	WAIT_EVENT_SYNC_REP,
+	WAIT_EVENT_WAL_RECEIVER_EXIT,
+	WAIT_EVENT_WAL_RECEIVER_WAIT_START,
+	WAIT_EVENT_XACT_GROUP_UPDATE
+} WaitEventIPC;
+
+/* ----------
+ * Wait Events - Timeout
+ *
+ * Use this category when a process is waiting for a timeout to expire.
+ * ----------
+ */
+typedef enum
+{
+	WAIT_EVENT_BASE_BACKUP_THROTTLE = PG_WAIT_TIMEOUT,
+	WAIT_EVENT_PG_SLEEP,
+	WAIT_EVENT_RECOVERY_APPLY_DELAY,
+	WAIT_EVENT_RECOVERY_RETRIEVE_RETRY_INTERVAL,
+	WAIT_EVENT_VACUUM_DELAY
+} WaitEventTimeout;
+
+/* ----------
+ * Wait Events - IO
+ *
+ * Use this category when a process is waiting for a IO.
+ * ----------
+ */
+typedef enum
+{
+	WAIT_EVENT_BASEBACKUP_READ = PG_WAIT_IO,
+	WAIT_EVENT_BUFFILE_READ,
+	WAIT_EVENT_BUFFILE_WRITE,
+	WAIT_EVENT_BUFFILE_TRUNCATE,
+	WAIT_EVENT_CONTROL_FILE_READ,
+	WAIT_EVENT_CONTROL_FILE_SYNC,
+	WAIT_EVENT_CONTROL_FILE_SYNC_UPDATE,
+	WAIT_EVENT_CONTROL_FILE_WRITE,
+	WAIT_EVENT_CONTROL_FILE_WRITE_UPDATE,
+	WAIT_EVENT_COPY_FILE_READ,
+	WAIT_EVENT_COPY_FILE_WRITE,
+	WAIT_EVENT_DATA_FILE_EXTEND,
+	WAIT_EVENT_DATA_FILE_FLUSH,
+	WAIT_EVENT_DATA_FILE_IMMEDIATE_SYNC,
+	WAIT_EVENT_DATA_FILE_PREFETCH,
+	WAIT_EVENT_DATA_FILE_READ,
+	WAIT_EVENT_DATA_FILE_SYNC,
+	WAIT_EVENT_DATA_FILE_TRUNCATE,
+	WAIT_EVENT_DATA_FILE_WRITE,
+	WAIT_EVENT_DSM_FILL_ZERO_WRITE,
+	WAIT_EVENT_LOCK_FILE_ADDTODATADIR_READ,
+	WAIT_EVENT_LOCK_FILE_ADDTODATADIR_SYNC,
+	WAIT_EVENT_LOCK_FILE_ADDTODATADIR_WRITE,
+	WAIT_EVENT_LOCK_FILE_CREATE_READ,
+	WAIT_EVENT_LOCK_FILE_CREATE_SYNC,
+	WAIT_EVENT_LOCK_FILE_CREATE_WRITE,
+	WAIT_EVENT_LOCK_FILE_RECHECKDATADIR_READ,
+	WAIT_EVENT_LOGICAL_REWRITE_CHECKPOINT_SYNC,
+	WAIT_EVENT_LOGICAL_REWRITE_MAPPING_SYNC,
+	WAIT_EVENT_LOGICAL_REWRITE_MAPPING_WRITE,
+	WAIT_EVENT_LOGICAL_REWRITE_SYNC,
+	WAIT_EVENT_LOGICAL_REWRITE_TRUNCATE,
+	WAIT_EVENT_LOGICAL_REWRITE_WRITE,
+	WAIT_EVENT_RELATION_MAP_READ,
+	WAIT_EVENT_RELATION_MAP_SYNC,
+	WAIT_EVENT_RELATION_MAP_WRITE,
+	WAIT_EVENT_REORDER_BUFFER_READ,
+	WAIT_EVENT_REORDER_BUFFER_WRITE,
+	WAIT_EVENT_REORDER_LOGICAL_MAPPING_READ,
+	WAIT_EVENT_REPLICATION_SLOT_READ,
+	WAIT_EVENT_REPLICATION_SLOT_RESTORE_SYNC,
+	WAIT_EVENT_REPLICATION_SLOT_SYNC,
+	WAIT_EVENT_REPLICATION_SLOT_WRITE,
+	WAIT_EVENT_SLRU_FLUSH_SYNC,
+	WAIT_EVENT_SLRU_READ,
+	WAIT_EVENT_SLRU_SYNC,
+	WAIT_EVENT_SLRU_WRITE,
+	WAIT_EVENT_SNAPBUILD_READ,
+	WAIT_EVENT_SNAPBUILD_SYNC,
+	WAIT_EVENT_SNAPBUILD_WRITE,
+	WAIT_EVENT_TIMELINE_HISTORY_FILE_SYNC,
+	WAIT_EVENT_TIMELINE_HISTORY_FILE_WRITE,
+	WAIT_EVENT_TIMELINE_HISTORY_READ,
+	WAIT_EVENT_TIMELINE_HISTORY_SYNC,
+	WAIT_EVENT_TIMELINE_HISTORY_WRITE,
+	WAIT_EVENT_TWOPHASE_FILE_READ,
+	WAIT_EVENT_TWOPHASE_FILE_SYNC,
+	WAIT_EVENT_TWOPHASE_FILE_WRITE,
+	WAIT_EVENT_WALSENDER_TIMELINE_HISTORY_READ,
+	WAIT_EVENT_WAL_BOOTSTRAP_SYNC,
+	WAIT_EVENT_WAL_BOOTSTRAP_WRITE,
+	WAIT_EVENT_WAL_COPY_READ,
+	WAIT_EVENT_WAL_COPY_SYNC,
+	WAIT_EVENT_WAL_COPY_WRITE,
+	WAIT_EVENT_WAL_INIT_SYNC,
+	WAIT_EVENT_WAL_INIT_WRITE,
+	WAIT_EVENT_WAL_READ,
+	WAIT_EVENT_WAL_SYNC,
+	WAIT_EVENT_WAL_SYNC_METHOD_ASSIGN,
+	WAIT_EVENT_WAL_WRITE,
+	WAIT_EVENT_LOGICAL_CHANGES_READ,
+	WAIT_EVENT_LOGICAL_CHANGES_WRITE,
+	WAIT_EVENT_LOGICAL_SUBXACT_READ,
+	WAIT_EVENT_LOGICAL_SUBXACT_WRITE
+} WaitEventIO;
+
+
+extern const char *pgstat_get_wait_event(uint32 wait_event_info);
+extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
+static inline void pgstat_report_wait_start(uint32 wait_event_info);
+static inline void pgstat_report_wait_end(void);
+
+
+/*
+ * Repeated here for the inline functions because it is declared in pgstat.h,
+ * which includes this header.
+ */
+extern PGDLLIMPORT bool pgstat_track_activities;
+
+
+/* ----------
+ * pgstat_report_wait_start() -
+ *
+ *	Called from places where server process needs to wait.  This is called
+ *	to report wait event information.  The wait information is stored
+ *	as 4-bytes where first byte represents the wait event class (type of
+ *	wait, for different types of wait, refer WaitClass) and the next
+ *	3-bytes represent the actual wait event.  Currently 2-bytes are used
+ *	for wait event which is sufficient for current usage, 1-byte is
+ *	reserved for future usage.
+ *
+ * NB: this *must* be able to survive being called before MyProc has been
+ * initialized.
+ * ----------
+ */
+static inline void
+pgstat_report_wait_start(uint32 wait_event_info)
+{
+	volatile PGPROC *proc = MyProc;
+
+	if (!pgstat_track_activities || !proc)
+		return;
+
+	/*
+	 * Since this is a four-byte field which is always read and written as
+	 * four-bytes, updates are atomic.
+	 */
+	proc->wait_event_info = wait_event_info;
+}
+
+/* ----------
+ * pgstat_report_wait_end() -
+ *
+ *	Called to report end of a wait.
+ *
+ * NB: this *must* be able to survive being called before MyProc has been
+ * initialized.
+ * ----------
+ */
+static inline void
+pgstat_report_wait_end(void)
+{
+	volatile PGPROC *proc = MyProc;
+
+	if (!pgstat_track_activities || !proc)
+		return;
+
+	/*
+	 * Since this is a four-byte field which is always read and written as
+	 * four-bytes, updates are atomic.
+	 */
+	proc->wait_event_info = 0;
+}
+
+
+#endif /* WAIT_EVENT_H */