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/*-------------------------------------------------------------------------
* wait_event.h
* Definitions related to wait event reporting
*
* Copyright (c) 2001-2025, PostgreSQL Global Development Group
*
* src/include/utils/wait_event.h
* ----------
*/
#ifndef WAIT_EVENT_H
#define WAIT_EVENT_H
/* enums for wait events */
#include "utils/wait_event_types.h"
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);
extern void pgstat_set_wait_event_storage(uint32 *wait_event_info);
extern void pgstat_reset_wait_event_storage(void);
extern PGDLLIMPORT uint32 *my_wait_event_info;
/*
* Wait Events - Extension, InjectionPoint
*
* Use InjectionPoint when the server process is waiting in an injection
* point. Use Extension for other cases of the server process waiting for
* some condition defined by an extension module.
*
* Extensions can define their own wait events in these categories. They
* should call one of these functions with a wait event string. If the wait
* event associated to a string is already allocated, it returns the wait
* event information to use. If not, it gets one wait event ID allocated from
* a shared counter, associates the string to the ID in the shared dynamic
* hash and returns the wait event information.
*
* The ID retrieved can be used with pgstat_report_wait_start() or equivalent.
*/
extern uint32 WaitEventExtensionNew(const char *wait_event_name);
extern uint32 WaitEventInjectionPointNew(const char *wait_event_name);
extern void WaitEventCustomShmemInit(void);
extern Size WaitEventCustomShmemSize(void);
extern char **GetWaitEventCustomNames(uint32 classId, int *nwaitevents);
/* ----------
* 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.
*
* Historically we used to make this reporting conditional on
* pgstat_track_activities, but the check for that seems to add more cost
* than it saves.
*
* my_wait_event_info initially points to local memory, making it safe to
* call this before MyProc has been initialized.
* ----------
*/
static inline void
pgstat_report_wait_start(uint32 wait_event_info)
{
/*
* Since this is a four-byte field which is always read and written as
* four-bytes, updates are atomic.
*/
*(volatile uint32 *) my_wait_event_info = wait_event_info;
}
/* ----------
* pgstat_report_wait_end() -
*
* Called to report end of a wait.
* ----------
*/
static inline void
pgstat_report_wait_end(void)
{
/* see pgstat_report_wait_start() */
*(volatile uint32 *) my_wait_event_info = 0;
}
#endif /* WAIT_EVENT_H */
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