wait_event_funcs.c

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/*------------------------------------------------------------------------
 *
 * wait_event_funcs.c
 *    Functions for accessing wait event data.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/activity/wait_event_funcs.c
 *
 *------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "funcapi.h"
#include "utils/builtins.h"
#include "utils/wait_event.h"
 
/*
 * Each wait event has one corresponding entry in this structure, fed to
 * the SQL function of this file.
 */
static const struct
{
    const char *type;
    const char *name;
    const char *description;
}
 
            waitEventData[] =
{
#include "wait_event_funcs_data.c"
    /* end of list */
    {NULL, NULL, NULL}
};
 
 
/*
 * pg_get_wait_events
 *
 * List information about wait events (type, name and description).
 */
Datum
pg_get_wait_events(PG_FUNCTION_ARGS)
{
#define PG_GET_WAIT_EVENTS_COLS 3
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    char      **waiteventnames;
    int         nbwaitevents;
 
    /* Build tuplestore to hold the result rows */
    InitMaterializedSRF(fcinfo, 0);
 
    /* Iterate over the list of wait events */
    for (int idx = 0; waitEventData[idx].type != NULL; idx++)
    {
        Datum       values[PG_GET_WAIT_EVENTS_COLS] = {0};
        bool        nulls[PG_GET_WAIT_EVENTS_COLS] = {0};
 
        values[0] = CStringGetTextDatum(waitEventData[idx].type);
        values[1] = CStringGetTextDatum(waitEventData[idx].name);
        values[2] = CStringGetTextDatum(waitEventData[idx].description);
 
        tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
    }
 
    /* Handle custom wait events for extensions */
    waiteventnames = GetWaitEventCustomNames(PG_WAIT_EXTENSION,
                                             &nbwaitevents);
 
    for (int idx = 0; idx < nbwaitevents; idx++)
    {
        StringInfoData buf;
        Datum       values[PG_GET_WAIT_EVENTS_COLS] = {0};
        bool        nulls[PG_GET_WAIT_EVENTS_COLS] = {0};
 
 
        values[0] = CStringGetTextDatum("Extension");
        values[1] = CStringGetTextDatum(waiteventnames[idx]);
 
        initStringInfo(&buf);
        appendStringInfo(&buf,
                         "Waiting for custom wait event \"%s\" defined by extension module",
                         waiteventnames[idx]);
 
        values[2] = CStringGetTextDatum(buf.data);
 
        tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
    }
 
    /* Likewise for injection points */
    waiteventnames = GetWaitEventCustomNames(PG_WAIT_INJECTIONPOINT,
                                             &nbwaitevents);
 
    for (int idx = 0; idx < nbwaitevents; idx++)
    {
        StringInfoData buf;
        Datum       values[PG_GET_WAIT_EVENTS_COLS] = {0};
        bool        nulls[PG_GET_WAIT_EVENTS_COLS] = {0};
 
 
        values[0] = CStringGetTextDatum("InjectionPoint");
        values[1] = CStringGetTextDatum(waiteventnames[idx]);
 
        initStringInfo(&buf);
        appendStringInfo(&buf,
                         "Waiting for injection point \"%s\"",
                         waiteventnames[idx]);
 
        values[2] = CStringGetTextDatum(buf.data);
 
        tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
    }
 
    return (Datum) 0;
}