Line data Source code
1 : /*--------------------------------------------------------------------------
2 : *
3 : * test_custom_fixed_stats.c
4 : * Test module for fixed-sized custom pgstats
5 : *
6 : * Copyright (c) 2025-2026, PostgreSQL Global Development Group
7 : *
8 : * IDENTIFICATION
9 : * src/test/modules/test_custom_stats/test_custom_fixed_stats.c
10 : *
11 : * -------------------------------------------------------------------------
12 : */
13 :
14 : #include "postgres.h"
15 :
16 : #include "access/htup_details.h"
17 : #include "funcapi.h"
18 : #include "pgstat.h"
19 : #include "utils/builtins.h"
20 : #include "utils/pgstat_internal.h"
21 :
22 0 : PG_MODULE_MAGIC_EXT(
23 : .name = "test_custom_fixed_stats",
24 : .version = PG_VERSION
25 : );
26 :
27 : /* Fixed-amount custom statistics entry */
28 : typedef struct PgStat_StatCustomFixedEntry
29 : {
30 : PgStat_Counter numcalls; /* # of times update function called */
31 : TimestampTz stat_reset_timestamp;
32 : } PgStat_StatCustomFixedEntry;
33 :
34 : typedef struct PgStatShared_CustomFixedEntry
35 : {
36 : LWLock lock; /* protects counters */
37 : uint32 changecount; /* for atomic reads */
38 : PgStat_StatCustomFixedEntry stats; /* current counters */
39 : PgStat_StatCustomFixedEntry reset_offset; /* reset baseline */
40 : } PgStatShared_CustomFixedEntry;
41 :
42 : /* Callbacks for fixed-amount statistics */
43 : static void test_custom_stats_fixed_init_shmem_cb(void *stats);
44 : static void test_custom_stats_fixed_reset_all_cb(TimestampTz ts);
45 : static void test_custom_stats_fixed_snapshot_cb(void);
46 :
47 : static const PgStat_KindInfo custom_stats = {
48 : .name = "test_custom_fixed_stats",
49 : .fixed_amount = true, /* exactly one entry */
50 : .write_to_file = true, /* persist to stats file */
51 :
52 : .shared_size = sizeof(PgStat_StatCustomFixedEntry),
53 : .shared_data_off = offsetof(PgStatShared_CustomFixedEntry, stats),
54 : .shared_data_len = sizeof(((PgStatShared_CustomFixedEntry *) 0)->stats),
55 :
56 : .init_shmem_cb = test_custom_stats_fixed_init_shmem_cb,
57 : .reset_all_cb = test_custom_stats_fixed_reset_all_cb,
58 : .snapshot_cb = test_custom_stats_fixed_snapshot_cb,
59 : };
60 :
61 : /*
62 : * Kind ID for test_custom_fixed_stats.
63 : */
64 : #define PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS 26
65 :
66 : /*--------------------------------------------------------------------------
67 : * Module initialization
68 : *--------------------------------------------------------------------------
69 : */
70 :
71 : void
72 0 : _PG_init(void)
73 : {
74 : /* Must be loaded via shared_preload_libraries */
75 0 : if (!process_shared_preload_libraries_in_progress)
76 0 : return;
77 :
78 : /* Register custom statistics kind */
79 0 : pgstat_register_kind(PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS, &custom_stats);
80 0 : }
81 :
82 : /*
83 : * test_custom_stats_fixed_init_shmem_cb
84 : * Initialize shared memory structure
85 : */
86 : static void
87 0 : test_custom_stats_fixed_init_shmem_cb(void *stats)
88 : {
89 0 : PgStatShared_CustomFixedEntry *stats_shmem =
90 0 : (PgStatShared_CustomFixedEntry *) stats;
91 :
92 0 : LWLockInitialize(&stats_shmem->lock, LWTRANCHE_PGSTATS_DATA);
93 0 : }
94 :
95 : /*
96 : * test_custom_stats_fixed_reset_all_cb
97 : * Reset the fixed-sized stats
98 : */
99 : static void
100 0 : test_custom_stats_fixed_reset_all_cb(TimestampTz ts)
101 : {
102 0 : PgStatShared_CustomFixedEntry *stats_shmem =
103 0 : pgstat_get_custom_shmem_data(PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS);
104 :
105 : /* see explanation above PgStatShared_Archiver for the reset protocol */
106 0 : LWLockAcquire(&stats_shmem->lock, LW_EXCLUSIVE);
107 0 : pgstat_copy_changecounted_stats(&stats_shmem->reset_offset,
108 0 : &stats_shmem->stats,
109 : sizeof(stats_shmem->stats),
110 0 : &stats_shmem->changecount);
111 0 : stats_shmem->stats.stat_reset_timestamp = ts;
112 0 : LWLockRelease(&stats_shmem->lock);
113 0 : }
114 :
115 : /*
116 : * test_custom_stats_fixed_snapshot_cb
117 : * Copy current stats to snapshot area
118 : */
119 : static void
120 0 : test_custom_stats_fixed_snapshot_cb(void)
121 : {
122 0 : PgStatShared_CustomFixedEntry *stats_shmem =
123 0 : pgstat_get_custom_shmem_data(PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS);
124 0 : PgStat_StatCustomFixedEntry *stat_snap =
125 0 : pgstat_get_custom_snapshot_data(PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS);
126 0 : PgStat_StatCustomFixedEntry *reset_offset = &stats_shmem->reset_offset;
127 0 : PgStat_StatCustomFixedEntry reset;
128 :
129 0 : pgstat_copy_changecounted_stats(stat_snap,
130 0 : &stats_shmem->stats,
131 : sizeof(stats_shmem->stats),
132 0 : &stats_shmem->changecount);
133 :
134 0 : LWLockAcquire(&stats_shmem->lock, LW_SHARED);
135 0 : memcpy(&reset, reset_offset, sizeof(stats_shmem->stats));
136 0 : LWLockRelease(&stats_shmem->lock);
137 :
138 : /* Apply reset offsets */
139 : #define FIXED_COMP(fld) stat_snap->fld -= reset.fld;
140 0 : FIXED_COMP(numcalls);
141 : #undef FIXED_COMP
142 0 : }
143 :
144 : /*--------------------------------------------------------------------------
145 : * SQL-callable functions
146 : *--------------------------------------------------------------------------
147 : */
148 :
149 : /*
150 : * test_custom_stats_fixed_update
151 : * Increment call counter
152 : */
153 0 : PG_FUNCTION_INFO_V1(test_custom_stats_fixed_update);
154 : Datum
155 0 : test_custom_stats_fixed_update(PG_FUNCTION_ARGS)
156 : {
157 0 : PgStatShared_CustomFixedEntry *stats_shmem;
158 :
159 0 : stats_shmem = pgstat_get_custom_shmem_data(PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS);
160 :
161 0 : LWLockAcquire(&stats_shmem->lock, LW_EXCLUSIVE);
162 :
163 0 : pgstat_begin_changecount_write(&stats_shmem->changecount);
164 0 : stats_shmem->stats.numcalls++;
165 0 : pgstat_end_changecount_write(&stats_shmem->changecount);
166 :
167 0 : LWLockRelease(&stats_shmem->lock);
168 :
169 0 : PG_RETURN_VOID();
170 0 : }
171 :
172 : /*
173 : * test_custom_stats_fixed_reset
174 : * Reset statistics by calling pgstat system
175 : */
176 0 : PG_FUNCTION_INFO_V1(test_custom_stats_fixed_reset);
177 : Datum
178 0 : test_custom_stats_fixed_reset(PG_FUNCTION_ARGS)
179 : {
180 0 : pgstat_reset_of_kind(PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS);
181 :
182 0 : PG_RETURN_VOID();
183 : }
184 :
185 : /*
186 : * test_custom_stats_fixed_report
187 : * Return current counter values
188 : */
189 0 : PG_FUNCTION_INFO_V1(test_custom_stats_fixed_report);
190 : Datum
191 0 : test_custom_stats_fixed_report(PG_FUNCTION_ARGS)
192 : {
193 0 : TupleDesc tupdesc;
194 0 : Datum values[2] = {0};
195 0 : bool nulls[2] = {false};
196 0 : PgStat_StatCustomFixedEntry *stats;
197 :
198 : /* Take snapshot (applies reset offsets) */
199 0 : pgstat_snapshot_fixed(PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS);
200 0 : stats = pgstat_get_custom_snapshot_data(PGSTAT_KIND_TEST_CUSTOM_FIXED_STATS);
201 :
202 : /* Build return tuple */
203 0 : tupdesc = CreateTemplateTupleDesc(2);
204 0 : TupleDescInitEntry(tupdesc, (AttrNumber) 1, "numcalls",
205 : INT8OID, -1, 0);
206 0 : TupleDescInitEntry(tupdesc, (AttrNumber) 2, "stats_reset",
207 : TIMESTAMPTZOID, -1, 0);
208 0 : BlessTupleDesc(tupdesc);
209 :
210 0 : values[0] = Int64GetDatum(stats->numcalls);
211 :
212 : /* Handle uninitialized timestamp (no reset yet) */
213 0 : if (stats->stat_reset_timestamp == 0)
214 : {
215 0 : nulls[1] = true;
216 0 : }
217 : else
218 : {
219 0 : values[1] = TimestampTzGetDatum(stats->stat_reset_timestamp);
220 : }
221 :
222 : /* Return as tuple */
223 0 : PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
224 0 : }
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