Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  * wait_event.h
       3             :  *    Definitions related to wait event reporting
       4             :  *
       5             :  * Copyright (c) 2001-2024, PostgreSQL Global Development Group
       6             :  *
       7             :  * src/include/utils/wait_event.h
       8             :  * ----------
       9             :  */
      10             : #ifndef WAIT_EVENT_H
      11             : #define WAIT_EVENT_H
      12             : 
      13             : 
      14             : /* ----------
      15             :  * Wait Classes
      16             :  * ----------
      17             :  */
      18             : #define PG_WAIT_LWLOCK              0x01000000U
      19             : #define PG_WAIT_LOCK                0x03000000U
      20             : #define PG_WAIT_BUFFERPIN           0x04000000U
      21             : #define PG_WAIT_ACTIVITY            0x05000000U
      22             : #define PG_WAIT_CLIENT              0x06000000U
      23             : #define PG_WAIT_EXTENSION           0x07000000U
      24             : #define PG_WAIT_IPC                 0x08000000U
      25             : #define PG_WAIT_TIMEOUT             0x09000000U
      26             : #define PG_WAIT_IO                  0x0A000000U
      27             : 
      28             : /* enums for wait events */
      29             : #include "utils/wait_event_types.h"
      30             : 
      31             : extern const char *pgstat_get_wait_event(uint32 wait_event_info);
      32             : extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
      33             : static inline void pgstat_report_wait_start(uint32 wait_event_info);
      34             : static inline void pgstat_report_wait_end(void);
      35             : extern void pgstat_set_wait_event_storage(uint32 *wait_event_info);
      36             : extern void pgstat_reset_wait_event_storage(void);
      37             : 
      38             : extern PGDLLIMPORT uint32 *my_wait_event_info;
      39             : 
      40             : 
      41             : /* ----------
      42             :  * Wait Events - Extension
      43             :  *
      44             :  * Use this category when the server process is waiting for some condition
      45             :  * defined by an extension module.
      46             :  *
      47             :  * Extensions can define their own wait events in this category.  They should
      48             :  * call WaitEventExtensionNew() with a wait event string.  If the wait event
      49             :  * associated to a string is already allocated, it returns the wait event
      50             :  * information to use.  If not, it gets one wait event ID allocated from
      51             :  * a shared counter, associates the string to the ID in the shared dynamic
      52             :  * hash and returns the wait event information.
      53             :  *
      54             :  * The ID retrieved can be used with pgstat_report_wait_start() or equivalent.
      55             :  */
      56             : typedef enum
      57             : {
      58             :     WAIT_EVENT_EXTENSION = PG_WAIT_EXTENSION,
      59             :     WAIT_EVENT_EXTENSION_FIRST_USER_DEFINED,
      60             : } WaitEventExtension;
      61             : 
      62             : extern void WaitEventExtensionShmemInit(void);
      63             : extern Size WaitEventExtensionShmemSize(void);
      64             : 
      65             : extern uint32 WaitEventExtensionNew(const char *wait_event_name);
      66             : extern char **GetWaitEventExtensionNames(int *nwaitevents);
      67             : 
      68             : /* ----------
      69             :  * pgstat_report_wait_start() -
      70             :  *
      71             :  *  Called from places where server process needs to wait.  This is called
      72             :  *  to report wait event information.  The wait information is stored
      73             :  *  as 4-bytes where first byte represents the wait event class (type of
      74             :  *  wait, for different types of wait, refer WaitClass) and the next
      75             :  *  3-bytes represent the actual wait event.  Currently 2-bytes are used
      76             :  *  for wait event which is sufficient for current usage, 1-byte is
      77             :  *  reserved for future usage.
      78             :  *
      79             :  *  Historically we used to make this reporting conditional on
      80             :  *  pgstat_track_activities, but the check for that seems to add more cost
      81             :  *  than it saves.
      82             :  *
      83             :  *  my_wait_event_info initially points to local memory, making it safe to
      84             :  *  call this before MyProc has been initialized.
      85             :  * ----------
      86             :  */
      87             : static inline void
      88    11523996 : pgstat_report_wait_start(uint32 wait_event_info)
      89             : {
      90             :     /*
      91             :      * Since this is a four-byte field which is always read and written as
      92             :      * four-bytes, updates are atomic.
      93             :      */
      94    11523996 :     *(volatile uint32 *) my_wait_event_info = wait_event_info;
      95    11523996 : }
      96             : 
      97             : /* ----------
      98             :  * pgstat_report_wait_end() -
      99             :  *
     100             :  *  Called to report end of a wait.
     101             :  * ----------
     102             :  */
     103             : static inline void
     104    11582468 : pgstat_report_wait_end(void)
     105             : {
     106             :     /* see pgstat_report_wait_start() */
     107    11582468 :     *(volatile uint32 *) my_wait_event_info = 0;
     108    11582468 : }
     109             : 
     110             : 
     111             : #endif                          /* WAIT_EVENT_H */