Add statistics of pg_store_plans

[pgstoreplans/pg_store_plans.git] / pg_store_plans.c

diff --git a/pg_store_plans.c b/pg_store_plans.c
index 62d9ec3..526617f 100644 (file)
--- a/pg_store_plans.c
+++ b/pg_store_plans.c
@@ -148,6 +148,15 @@ typedef struct Counters
 } Counters;
 
 /*
+ * Global statistics for pg_store_plans
+ */
+typedef struct pgspGlobalStats
+{
+       int64           dealloc;                /* # of times entries were deallocated */
+       TimestampTz stats_reset;        /* timestamp with all stats reset */
+} pgspGlobalStats;
+
+/*
  * Statistics per plan
  *
  * NB: see the file read/write code before changing field order here.
@@ -175,6 +184,7 @@ typedef struct pgspSharedState
        Size            extent;                 /* current extent of plan file */
        int                     n_writers;              /* number of active writers to query file */
        int                     gc_count;               /* plan file garbage collection cycle count */
+       pgspGlobalStats stats;          /* global statistics for pgsp */
 } pgspSharedState;
 
 /*---- Local variables ----*/
@@ -291,6 +301,7 @@ Datum               pg_store_plans_jsonplan(PG_FUNCTION_ARGS);
 Datum          pg_store_plans_yamlplan(PG_FUNCTION_ARGS);
 Datum          pg_store_plans_xmlplan(PG_FUNCTION_ARGS);
 Datum          pg_store_plans_textplan(PG_FUNCTION_ARGS);
+Datum          pg_store_plans_info(PG_FUNCTION_ARGS);
 
 PG_FUNCTION_INFO_V1(pg_store_plans_reset);
 PG_FUNCTION_INFO_V1(pg_store_plans_hash_query);
@@ -299,9 +310,10 @@ PG_FUNCTION_INFO_V1(pg_store_plans_1_6);
 PG_FUNCTION_INFO_V1(pg_store_plans_shorten);
 PG_FUNCTION_INFO_V1(pg_store_plans_normalize);
 PG_FUNCTION_INFO_V1(pg_store_plans_jsonplan);
-PG_FUNCTION_INFO_V1(pg_store_plans_textplan);
 PG_FUNCTION_INFO_V1(pg_store_plans_yamlplan);
 PG_FUNCTION_INFO_V1(pg_store_plans_xmlplan);
+PG_FUNCTION_INFO_V1(pg_store_plans_textplan);
+PG_FUNCTION_INFO_V1(pg_store_plans_info);
 
 #if PG_VERSION_NUM < 130000
 #define COMPTAG_TYPE char
@@ -604,6 +616,8 @@ pgsp_shmem_startup(void)
                shared_state->extent = 0;
                shared_state->n_writers = 0;
                shared_state->gc_count = 0;
+               shared_state->stats.dealloc = 0;
+               shared_state->stats.stats_reset = GetCurrentTimestamp();
        }
 
        /* Be sure everyone agrees on the hash table entry size */
@@ -1576,6 +1590,47 @@ pg_store_plans_internal(FunctionCallInfo fcinfo,
        tuplestore_donestoring(tupstore);
 }
 
+/* Number of output arguments (columns) for pg_stat_statements_info */
+#define PG_STORE_PLANS_INFO_COLS       2
+
+/*
+ * Return statistics of pg_stat_statements.
+ */
+Datum
+pg_store_plans_info(PG_FUNCTION_ARGS)
+{
+       pgspGlobalStats stats;
+       TupleDesc       tupdesc;
+       Datum           values[PG_STORE_PLANS_INFO_COLS];
+       bool            nulls[PG_STORE_PLANS_INFO_COLS];
+
+       if (!shared_state || !hash_table)
+               ereport(ERROR,
+                               (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+                                errmsg("pg_store_plans must be loaded via shared_preload_libraries")));
+
+       /* Build a tuple descriptor for our result type */
+       if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+               elog(ERROR, "return type must be a row type");
+
+       MemSet(values, 0, sizeof(values));
+       MemSet(nulls, 0, sizeof(nulls));
+
+       /* Read global statistics for pg_stat_statements */
+       {
+               volatile pgspSharedState *s = (volatile pgspSharedState *) shared_state;
+
+               SpinLockAcquire(&s->mutex);
+               stats = s->stats;
+               SpinLockRelease(&s->mutex);
+       }
+
+       values[0] = Int64GetDatum(stats.dealloc);
+       values[1] = TimestampTzGetDatum(stats.stats_reset);
+
+       PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
+}
+
 /*
  * Estimate shared memory space needed.
  */
@@ -1726,6 +1781,15 @@ entry_dealloc(void)
        }
 
        pfree(entries);
+
+       /* Increment the number of times entries are deallocated */
+       {
+               volatile pgspSharedState *s = (volatile pgspSharedState *) shared_state;
+
+               SpinLockAcquire(&s->mutex);
+               s->stats.dealloc += 1;
+               SpinLockRelease(&s->mutex);
+       }
 }
 
 /*
@@ -2179,6 +2243,19 @@ entry_reset(void)
        }
 
        /*
+        * Reset global statistics for pg_store_plans.
+        */
+       {
+               volatile pgspSharedState *s = (volatile pgspSharedState *) shared_state;
+               TimestampTz stats_reset = GetCurrentTimestamp();
+
+               SpinLockAcquire(&s->mutex);
+               s->stats.dealloc = 0;
+               s->stats.stats_reset = stats_reset;
+               SpinLockRelease(&s->mutex);
+       }
+
+       /*
         * Write new empty plan file, perhaps even creating a new one to recover
         * if the file was missing.
         */