Quelle  injection_stats.c

/*--------------------------------------------------------------------------
 *
 * injection_stats.c
 *  Code for statistics of injection points.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *  src/test/modules/injection_points/injection_stats.c
 *
 * -------------------------------------------------------------------------
 */

#include "postgres.h"

#include "fmgr.h"

#include "common/hashfn.h"
#include "injection_stats.h"
#include "pgstat.h"
#include "utils/builtins.h"
#include "utils/pgstat_internal.h"

/* Structures for statistics of injection points */
typedef struct PgStat_StatInjEntry
{
 PgStat_Counter numcalls; /* number of times point has been run */
} PgStat_StatInjEntry;

typedef struct PgStatShared_InjectionPoint
{
 PgStatShared_Common header;
 PgStat_StatInjEntry stats;
} PgStatShared_InjectionPoint;

static bool injection_stats_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);

static const PgStat_KindInfo injection_stats = {
 .name = "injection_points",
 .fixed_amount = false,  /* Bounded by the number of points */
 .write_to_file = true,

 /* Injection points are system-wide */
 .accessed_across_databases = true,

 .shared_size = sizeof(PgStatShared_InjectionPoint),
 .shared_data_off = offsetof(PgStatShared_InjectionPoint, stats),
 .shared_data_len = sizeof(((PgStatShared_InjectionPoint *) 0)->stats),
 .pending_size = sizeof(PgStat_StatInjEntry),
 .flush_pending_cb = injection_stats_flush_cb,
};

/*
 * Compute stats entry idx from point name with an 8-byte hash.
 */
#define PGSTAT_INJ_IDX(name) hash_bytes_extended((const unsigned char *) name, strlen(name), 0)

/*
 * Kind ID reserved for statistics of injection points.
 */
#define PGSTAT_KIND_INJECTION 25

/* Track if stats are loaded */
static bool inj_stats_loaded = false;

/*
 * Callback for stats handling
 */
static bool
injection_stats_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
{
 PgStat_StatInjEntry *localent;
 PgStatShared_InjectionPoint *shfuncent;

 localent = (PgStat_StatInjEntry *) entry_ref->pending;
 shfuncent = (PgStatShared_InjectionPoint *) entry_ref->shared_stats;

 if (!pgstat_lock_entry(entry_ref, nowait))
  return false;

 shfuncent->stats.numcalls += localent->numcalls;

 pgstat_unlock_entry(entry_ref);

 return true;
}

/*
 * Support function for the SQL-callable pgstat* functions.  Returns
 * a pointer to the injection point statistics struct.
 */
static PgStat_StatInjEntry *
pgstat_fetch_stat_injentry(const char *name)
{
 PgStat_StatInjEntry *entry = NULL;

 if (!inj_stats_loaded || !inj_stats_enabled)
  return NULL;

 /* Compile the lookup key as a hash of the point name */
 entry = (PgStat_StatInjEntry *) pgstat_fetch_entry(PGSTAT_KIND_INJECTION,
                InvalidOid,
                PGSTAT_INJ_IDX(name));
 return entry;
}

/*
 * Workhorse to do the registration work, called in _PG_init().
 */
void
pgstat_register_inj(void)
{
 pgstat_register_kind(PGSTAT_KIND_INJECTION, &injection_stats);

 /* mark stats as loaded */
 inj_stats_loaded = true;
}

/*
 * Report injection point creation.
 */
void
pgstat_create_inj(const char *name)
{
 PgStat_EntryRef *entry_ref;
 PgStatShared_InjectionPoint *shstatent;

 /* leave if disabled */
 if (!inj_stats_loaded || !inj_stats_enabled)
  return;

 entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_INJECTION, InvalidOid,
            PGSTAT_INJ_IDX(name), NULL);

 shstatent = (PgStatShared_InjectionPoint *) entry_ref->shared_stats;

 /* initialize shared memory data */
 memset(&shstatent->stats, 0, sizeof(shstatent->stats));
}

/*
 * Report injection point drop.
 */
void
pgstat_drop_inj(const char *name)
{
 /* leave if disabled */
 if (!inj_stats_loaded || !inj_stats_enabled)
  return;

 if (!pgstat_drop_entry(PGSTAT_KIND_INJECTION, InvalidOid,
         PGSTAT_INJ_IDX(name)))
  pgstat_request_entry_refs_gc();
}

/*
 * Report statistics for injection point.
 *
 * This is simple because the set of stats to report currently is simple:
 * track the number of times a point has been run.
 */
void
pgstat_report_inj(const char *name)
{
 PgStat_EntryRef *entry_ref;
 PgStat_StatInjEntry *pending;

 /* leave if disabled */
 if (!inj_stats_loaded || !inj_stats_enabled)
  return;

 entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_INJECTION, InvalidOid,
            PGSTAT_INJ_IDX(name), NULL);

 pending = (PgStat_StatInjEntry *) entry_ref->pending;

 /* Update the injection point pending statistics */
 pending->numcalls++;
}

/*
 * SQL function returning the number of times an injection point
 * has been called.
 */
PG_FUNCTION_INFO_V1(injection_points_stats_numcalls);
Datum
injection_points_stats_numcalls(PG_FUNCTION_ARGS)
{
 char    *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 PgStat_StatInjEntry *entry = pgstat_fetch_stat_injentry(name);

 if (entry == NULL)
  PG_RETURN_NULL();

 PG_RETURN_INT64(entry->numcalls);
}

/* Only used by injection_points_stats_drop() */
static bool
match_inj_entries(PgStatShared_HashEntry *entry, Datum match_data)
{
 return entry->key.kind == PGSTAT_KIND_INJECTION;
}

/*
 * SQL function that drops all injection point statistics.
 */
PG_FUNCTION_INFO_V1(injection_points_stats_drop);
Datum
injection_points_stats_drop(PG_FUNCTION_ARGS)
{
 pgstat_drop_matching_entries(match_inj_entries, 0);

 PG_RETURN_VOID();
}