src/test/modules/injection_points/injection_stats.c

   1 /*--------------------------------------------------------------------------
   2  *
   3  * injection_stats.c
   4  *              Code for statistics of injection points.
   5  *
   6  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  * IDENTIFICATION
  10  *              src/test/modules/injection_points/injection_stats.c
  11  *
  12  * -------------------------------------------------------------------------
  13  */
  14
  15 #include "postgres.h"
  16
  17 #include "fmgr.h"
  18
  19 #include "common/hashfn.h"
  20 #include "injection_stats.h"
  21 #include "pgstat.h"
  22 #include "utils/builtins.h"
  23 #include "utils/pgstat_internal.h"
  24
  25 /* Structures for statistics of injection points */
  26 typedef struct PgStat_StatInjEntry
  27 {
  28         PgStat_Counter numcalls;        /* number of times point has been run */
  29 } PgStat_StatInjEntry;
  30
  31 typedef struct PgStatShared_InjectionPoint
  32 {
  33         PgStatShared_Common header;
  34         PgStat_StatInjEntry stats;
  35 } PgStatShared_InjectionPoint;
  36
  37 static bool injection_stats_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
  38
  39 static const PgStat_KindInfo injection_stats = {
  40         .name = "injection_points",
  41         .fixed_amount = false,          /* Bounded by the number of points */
  42         .write_to_file = true,
  43
  44         /* Injection points are system-wide */
  45         .accessed_across_databases = true,
  46
  47         .shared_size = sizeof(PgStatShared_InjectionPoint),
  48         .shared_data_off = offsetof(PgStatShared_InjectionPoint, stats),
  49         .shared_data_len = sizeof(((PgStatShared_InjectionPoint *) 0)->stats),
  50         .pending_size = sizeof(PgStat_StatInjEntry),
  51         .flush_pending_cb = injection_stats_flush_cb,
  52 };
  53
  54 /*
  55  * Compute stats entry idx from point name with an 8-byte hash.
  56  */
  57 #define PGSTAT_INJ_IDX(name) hash_bytes_extended((const unsigned char *) name, strlen(name), 0)
  58
  59 /*
  60  * Kind ID reserved for statistics of injection points.
  61  */
  62 #define PGSTAT_KIND_INJECTION   129
  63
  64 /* Track if stats are loaded */
  65 static bool inj_stats_loaded = false;
  66
  67 /*
  68  * Callback for stats handling
  69  */
  70 static bool
  71 injection_stats_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
  72 {
  73         PgStat_StatInjEntry *localent;
  74         PgStatShared_InjectionPoint *shfuncent;
  75
  76         localent = (PgStat_StatInjEntry *) entry_ref->pending;
  77         shfuncent = (PgStatShared_InjectionPoint *) entry_ref->shared_stats;
  78
  79         if (!pgstat_lock_entry(entry_ref, nowait))
  80                 return false;
  81
  82         shfuncent->stats.numcalls += localent->numcalls;
  83         return true;
  84 }
  85
  86 /*
  87  * Support function for the SQL-callable pgstat* functions.  Returns
  88  * a pointer to the injection point statistics struct.
  89  */
  90 static PgStat_StatInjEntry *
  91 pgstat_fetch_stat_injentry(const char *name)
  92 {
  93         PgStat_StatInjEntry *entry = NULL;
  94
  95         if (!inj_stats_loaded || !inj_stats_enabled)
  96                 return NULL;
  97
  98         /* Compile the lookup key as a hash of the point name */
  99         entry = (PgStat_StatInjEntry *) pgstat_fetch_entry(PGSTAT_KIND_INJECTION,
 100                                                                                                            InvalidOid,
 101                                                                                                            PGSTAT_INJ_IDX(name));
 102         return entry;
 103 }
 104
 105 /*
 106  * Workhorse to do the registration work, called in _PG_init().
 107  */
 108 void
 109 pgstat_register_inj(void)
 110 {
 111         pgstat_register_kind(PGSTAT_KIND_INJECTION, &injection_stats);
 112
 113         /* mark stats as loaded */
 114         inj_stats_loaded = true;
 115 }
 116
 117 /*
 118  * Report injection point creation.
 119  */
 120 void
 121 pgstat_create_inj(const char *name)
 122 {
 123         PgStat_EntryRef *entry_ref;
 124         PgStatShared_InjectionPoint *shstatent;
 125
 126         /* leave if disabled */
 127         if (!inj_stats_loaded || !inj_stats_enabled)
 128                 return;
 129
 130         entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_INJECTION, InvalidOid,
 131                                                                                         PGSTAT_INJ_IDX(name), false);
 132         shstatent = (PgStatShared_InjectionPoint *) entry_ref->shared_stats;
 133
 134         /* initialize shared memory data */
 135         memset(&shstatent->stats, 0, sizeof(shstatent->stats));
 136         pgstat_unlock_entry(entry_ref);
 137 }
 138
 139 /*
 140  * Report injection point drop.
 141  */
 142 void
 143 pgstat_drop_inj(const char *name)
 144 {
 145         /* leave if disabled */
 146         if (!inj_stats_loaded || !inj_stats_enabled)
 147                 return;
 148
 149         if (!pgstat_drop_entry(PGSTAT_KIND_INJECTION, InvalidOid,
 150                                                    PGSTAT_INJ_IDX(name)))
 151                 pgstat_request_entry_refs_gc();
 152 }
 153
 154 /*
 155  * Report statistics for injection point.
 156  *
 157  * This is simple because the set of stats to report currently is simple:
 158  * track the number of times a point has been run.
 159  */
 160 void
 161 pgstat_report_inj(const char *name)
 162 {
 163         PgStat_EntryRef *entry_ref;
 164         PgStatShared_InjectionPoint *shstatent;
 165         PgStat_StatInjEntry *statent;
 166
 167         /* leave if disabled */
 168         if (!inj_stats_loaded || !inj_stats_enabled)
 169                 return;
 170
 171         entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_INJECTION, InvalidOid,
 172                                                                                         PGSTAT_INJ_IDX(name), false);
 173
 174         shstatent = (PgStatShared_InjectionPoint *) entry_ref->shared_stats;
 175         statent = &shstatent->stats;
 176
 177         /* Update the injection point statistics */
 178         statent->numcalls++;
 179
 180         pgstat_unlock_entry(entry_ref);
 181 }
 182
 183 /*
 184  * SQL function returning the number of times an injection point
 185  * has been called.
 186  */
 187 PG_FUNCTION_INFO_V1(injection_points_stats_numcalls);
 188 Datum
 189 injection_points_stats_numcalls(PG_FUNCTION_ARGS)
 190 {
 191         char       *name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 192         PgStat_StatInjEntry *entry = pgstat_fetch_stat_injentry(name);
 193
 194         if (entry == NULL)
 195                 PG_RETURN_NULL();
 196
 197         PG_RETURN_INT64(entry->numcalls);
 198 }