injection_stats_fixed.c

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/*--------------------------------------------------------------------------
 *
 * injection_stats_fixed.c
 *      Code for fixed-numbered 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_fixed.c
 *
 * -------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "fmgr.h"
 
#include "common/hashfn.h"
#include "funcapi.h"
#include "injection_stats.h"
#include "pgstat.h"
#include "utils/builtins.h"
#include "utils/pgstat_internal.h"
 
/* Structures for statistics of injection points, fixed-size */
typedef struct PgStat_StatInjFixedEntry
{
    PgStat_Counter numattach;   /* number of points attached */
    PgStat_Counter numdetach;   /* number of points detached */
    PgStat_Counter numrun;      /* number of points run */
    PgStat_Counter numcached;   /* number of points cached */
    PgStat_Counter numloaded;   /* number of points loaded */
    TimestampTz stat_reset_timestamp;
} PgStat_StatInjFixedEntry;
 
typedef struct PgStatShared_InjectionPointFixed
{
    LWLock      lock;           /* protects all the counters */
    uint32      changecount;
    PgStat_StatInjFixedEntry stats;
    PgStat_StatInjFixedEntry reset_offset;
} PgStatShared_InjectionPointFixed;
 
/* Callbacks for fixed-numbered stats */
static void injection_stats_fixed_init_shmem_cb(void *stats);
static void injection_stats_fixed_reset_all_cb(TimestampTz ts);
static void injection_stats_fixed_snapshot_cb(void);
 
static const PgStat_KindInfo injection_stats_fixed = {
    .name = "injection_points_fixed",
    .fixed_amount = true,
    .write_to_file = true,
 
    .shared_size = sizeof(PgStat_StatInjFixedEntry),
    .shared_data_off = offsetof(PgStatShared_InjectionPointFixed, stats),
    .shared_data_len = sizeof(((PgStatShared_InjectionPointFixed *) 0)->stats),
 
    .init_shmem_cb = injection_stats_fixed_init_shmem_cb,
    .reset_all_cb = injection_stats_fixed_reset_all_cb,
    .snapshot_cb = injection_stats_fixed_snapshot_cb,
};
 
/*
 * Kind ID reserved for statistics of injection points.
 */
#define PGSTAT_KIND_INJECTION_FIXED 130
 
/* Track if fixed-numbered stats are loaded */
static bool inj_fixed_loaded = false;
 
static void
injection_stats_fixed_init_shmem_cb(void *stats)
{
    PgStatShared_InjectionPointFixed *stats_shmem =
        (PgStatShared_InjectionPointFixed *) stats;
 
    LWLockInitialize(&stats_shmem->lock, LWTRANCHE_PGSTATS_DATA);
}
 
static void
injection_stats_fixed_reset_all_cb(TimestampTz ts)
{
    PgStatShared_InjectionPointFixed *stats_shmem =
        pgstat_get_custom_shmem_data(PGSTAT_KIND_INJECTION_FIXED);
 
    LWLockAcquire(&stats_shmem->lock, LW_EXCLUSIVE);
    pgstat_copy_changecounted_stats(&stats_shmem->reset_offset,
                                    &stats_shmem->stats,
                                    sizeof(stats_shmem->stats),
                                    &stats_shmem->changecount);
    stats_shmem->stats.stat_reset_timestamp = ts;
    LWLockRelease(&stats_shmem->lock);
}
 
static void
injection_stats_fixed_snapshot_cb(void)
{
    PgStatShared_InjectionPointFixed *stats_shmem =
        pgstat_get_custom_shmem_data(PGSTAT_KIND_INJECTION_FIXED);
    PgStat_StatInjFixedEntry *stat_snap =
        pgstat_get_custom_snapshot_data(PGSTAT_KIND_INJECTION_FIXED);
    PgStat_StatInjFixedEntry *reset_offset = &stats_shmem->reset_offset;
    PgStat_StatInjFixedEntry reset;
 
    pgstat_copy_changecounted_stats(stat_snap,
                                    &stats_shmem->stats,
                                    sizeof(stats_shmem->stats),
                                    &stats_shmem->changecount);
 
    LWLockAcquire(&stats_shmem->lock, LW_SHARED);
    memcpy(&reset, reset_offset, sizeof(stats_shmem->stats));
    LWLockRelease(&stats_shmem->lock);
 
    /* compensate by reset offsets */
#define FIXED_COMP(fld) stat_snap->fld -= reset.fld;
    FIXED_COMP(numattach);
    FIXED_COMP(numdetach);
    FIXED_COMP(numrun);
    FIXED_COMP(numcached);
    FIXED_COMP(numloaded);
#undef FIXED_COMP
}
 
/*
 * Workhorse to do the registration work, called in _PG_init().
 */
void
pgstat_register_inj_fixed(void)
{
    pgstat_register_kind(PGSTAT_KIND_INJECTION_FIXED, &injection_stats_fixed);
 
    /* mark stats as loaded */
    inj_fixed_loaded = true;
}
 
/*
 * Report fixed number of statistics for an injection point.
 */
void
pgstat_report_inj_fixed(uint32 numattach,
                        uint32 numdetach,
                        uint32 numrun,
                        uint32 numcached,
                        uint32 numloaded)
{
    PgStatShared_InjectionPointFixed *stats_shmem;
 
    /* leave if disabled */
    if (!inj_fixed_loaded || !inj_stats_enabled)
        return;
 
    stats_shmem = pgstat_get_custom_shmem_data(PGSTAT_KIND_INJECTION_FIXED);
 
    pgstat_begin_changecount_write(&stats_shmem->changecount);
    stats_shmem->stats.numattach += numattach;
    stats_shmem->stats.numdetach += numdetach;
    stats_shmem->stats.numrun += numrun;
    stats_shmem->stats.numcached += numcached;
    stats_shmem->stats.numloaded += numloaded;
    pgstat_end_changecount_write(&stats_shmem->changecount);
}
 
/*
 * SQL function returning fixed-numbered statistics for injection points.
 */
PG_FUNCTION_INFO_V1(injection_points_stats_fixed);
Datum
injection_points_stats_fixed(PG_FUNCTION_ARGS)
{
    TupleDesc   tupdesc;
    Datum       values[5] = {0};
    bool        nulls[5] = {0};
    PgStat_StatInjFixedEntry *stats;
 
    if (!inj_fixed_loaded || !inj_stats_enabled)
        PG_RETURN_NULL();
 
    pgstat_snapshot_fixed(PGSTAT_KIND_INJECTION_FIXED);
    stats = pgstat_get_custom_snapshot_data(PGSTAT_KIND_INJECTION_FIXED);
 
    /* Initialise attributes information in the tuple descriptor */
    tupdesc = CreateTemplateTupleDesc(5);
    TupleDescInitEntry(tupdesc, (AttrNumber) 1, "numattach",
                       INT8OID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 2, "numdetach",
                       INT8OID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 3, "numrun",
                       INT8OID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 4, "numcached",
                       INT8OID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 5, "numloaded",
                       INT8OID, -1, 0);
    BlessTupleDesc(tupdesc);
 
    values[0] = Int64GetDatum(stats->numattach);
    values[1] = Int64GetDatum(stats->numdetach);
    values[2] = Int64GetDatum(stats->numrun);
    values[3] = Int64GetDatum(stats->numcached);
    values[4] = Int64GetDatum(stats->numloaded);
    nulls[0] = false;
    nulls[1] = false;
    nulls[2] = false;
    nulls[3] = false;
    nulls[4] = false;
 
    /* Returns the record as Datum */
    PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
}