Line data Source code
1 : /* -------------------------------------------------------------------------
2 : *
3 : * pgstat_xact.c
4 : * Transactional integration for the cumulative statistics system.
5 : *
6 : * Copyright (c) 2001-2023, PostgreSQL Global Development Group
7 : *
8 : * IDENTIFICATION
9 : * src/backend/utils/activity/pgstat_xact.c
10 : * -------------------------------------------------------------------------
11 : */
12 :
13 : #include "postgres.h"
14 :
15 : #include "access/transam.h"
16 : #include "access/xact.h"
17 : #include "pgstat.h"
18 : #include "utils/memutils.h"
19 : #include "utils/pgstat_internal.h"
20 :
21 :
22 : typedef struct PgStat_PendingDroppedStatsItem
23 : {
24 : xl_xact_stats_item item;
25 : bool is_create;
26 : dlist_node node;
27 : } PgStat_PendingDroppedStatsItem;
28 :
29 :
30 : static void AtEOXact_PgStat_DroppedStats(PgStat_SubXactStatus *xact_state, bool isCommit);
31 : static void AtEOSubXact_PgStat_DroppedStats(PgStat_SubXactStatus *xact_state,
32 : bool isCommit, int nestDepth);
33 :
34 : static PgStat_SubXactStatus *pgStatXactStack = NULL;
35 :
36 :
37 : /*
38 : * Called from access/transam/xact.c at top-level transaction commit/abort.
39 : */
40 : void
41 515204 : AtEOXact_PgStat(bool isCommit, bool parallel)
42 : {
43 : PgStat_SubXactStatus *xact_state;
44 :
45 515204 : AtEOXact_PgStat_Database(isCommit, parallel);
46 :
47 : /* handle transactional stats information */
48 515204 : xact_state = pgStatXactStack;
49 515204 : if (xact_state != NULL)
50 : {
51 : Assert(xact_state->nest_level == 1);
52 : Assert(xact_state->prev == NULL);
53 :
54 195584 : AtEOXact_PgStat_Relations(xact_state, isCommit);
55 195584 : AtEOXact_PgStat_DroppedStats(xact_state, isCommit);
56 : }
57 515204 : pgStatXactStack = NULL;
58 :
59 : /* Make sure any stats snapshot is thrown away */
60 515204 : pgstat_clear_snapshot();
61 515204 : }
62 :
63 : /*
64 : * When committing, drop stats for objects dropped in the transaction. When
65 : * aborting, drop stats for objects created in the transaction.
66 : */
67 : static void
68 195584 : AtEOXact_PgStat_DroppedStats(PgStat_SubXactStatus *xact_state, bool isCommit)
69 : {
70 : dlist_mutable_iter iter;
71 195584 : int not_freed_count = 0;
72 :
73 195584 : if (dclist_count(&xact_state->pending_drops) == 0)
74 121436 : return;
75 :
76 259152 : dclist_foreach_modify(iter, &xact_state->pending_drops)
77 : {
78 185004 : PgStat_PendingDroppedStatsItem *pending =
79 185004 : dclist_container(PgStat_PendingDroppedStatsItem, node, iter.cur);
80 185004 : xl_xact_stats_item *it = &pending->item;
81 :
82 185004 : if (isCommit && !pending->is_create)
83 : {
84 : /*
85 : * Transaction that dropped an object committed. Drop the stats
86 : * too.
87 : */
88 65232 : if (!pgstat_drop_entry(it->kind, it->dboid, it->objoid))
89 9188 : not_freed_count++;
90 : }
91 119772 : else if (!isCommit && pending->is_create)
92 : {
93 : /*
94 : * Transaction that created an object aborted. Drop the stats
95 : * associated with the object.
96 : */
97 3566 : if (!pgstat_drop_entry(it->kind, it->dboid, it->objoid))
98 0 : not_freed_count++;
99 : }
100 :
101 185004 : dclist_delete_from(&xact_state->pending_drops, &pending->node);
102 185004 : pfree(pending);
103 : }
104 :
105 74148 : if (not_freed_count > 0)
106 3528 : pgstat_request_entry_refs_gc();
107 : }
108 :
109 : /*
110 : * Called from access/transam/xact.c at subtransaction commit/abort.
111 : */
112 : void
113 17988 : AtEOSubXact_PgStat(bool isCommit, int nestDepth)
114 : {
115 : PgStat_SubXactStatus *xact_state;
116 :
117 : /* merge the sub-transaction's transactional stats into the parent */
118 17988 : xact_state = pgStatXactStack;
119 17988 : if (xact_state != NULL &&
120 7516 : xact_state->nest_level >= nestDepth)
121 : {
122 : /* delink xact_state from stack immediately to simplify reuse case */
123 6658 : pgStatXactStack = xact_state->prev;
124 :
125 6658 : AtEOSubXact_PgStat_Relations(xact_state, isCommit, nestDepth);
126 6658 : AtEOSubXact_PgStat_DroppedStats(xact_state, isCommit, nestDepth);
127 :
128 6658 : pfree(xact_state);
129 : }
130 17988 : }
131 :
132 : /*
133 : * Like AtEOXact_PgStat_DroppedStats(), but for subtransactions.
134 : */
135 : static void
136 6658 : AtEOSubXact_PgStat_DroppedStats(PgStat_SubXactStatus *xact_state,
137 : bool isCommit, int nestDepth)
138 : {
139 : PgStat_SubXactStatus *parent_xact_state;
140 : dlist_mutable_iter iter;
141 6658 : int not_freed_count = 0;
142 :
143 6658 : if (dclist_count(&xact_state->pending_drops) == 0)
144 6514 : return;
145 :
146 144 : parent_xact_state = pgstat_get_xact_stack_level(nestDepth - 1);
147 :
148 422 : dclist_foreach_modify(iter, &xact_state->pending_drops)
149 : {
150 278 : PgStat_PendingDroppedStatsItem *pending =
151 278 : dclist_container(PgStat_PendingDroppedStatsItem, node, iter.cur);
152 278 : xl_xact_stats_item *it = &pending->item;
153 :
154 278 : dclist_delete_from(&xact_state->pending_drops, &pending->node);
155 :
156 278 : if (!isCommit && pending->is_create)
157 : {
158 : /*
159 : * Subtransaction creating a new stats object aborted. Drop the
160 : * stats object.
161 : */
162 138 : if (!pgstat_drop_entry(it->kind, it->dboid, it->objoid))
163 0 : not_freed_count++;
164 138 : pfree(pending);
165 : }
166 140 : else if (isCommit)
167 : {
168 : /*
169 : * Subtransaction dropping a stats object committed. Can't yet
170 : * remove the stats object, the surrounding transaction might
171 : * still abort. Pass it on to the parent.
172 : */
173 98 : dclist_push_tail(&parent_xact_state->pending_drops, &pending->node);
174 : }
175 : else
176 : {
177 42 : pfree(pending);
178 : }
179 : }
180 :
181 : Assert(dclist_count(&xact_state->pending_drops) == 0);
182 144 : if (not_freed_count > 0)
183 0 : pgstat_request_entry_refs_gc();
184 : }
185 :
186 : /*
187 : * Save the transactional stats state at 2PC transaction prepare.
188 : */
189 : void
190 762 : AtPrepare_PgStat(void)
191 : {
192 : PgStat_SubXactStatus *xact_state;
193 :
194 762 : xact_state = pgStatXactStack;
195 762 : if (xact_state != NULL)
196 : {
197 : Assert(xact_state->nest_level == 1);
198 : Assert(xact_state->prev == NULL);
199 :
200 748 : AtPrepare_PgStat_Relations(xact_state);
201 : }
202 762 : }
203 :
204 : /*
205 : * Clean up after successful PREPARE.
206 : *
207 : * Note: AtEOXact_PgStat is not called during PREPARE.
208 : */
209 : void
210 762 : PostPrepare_PgStat(void)
211 : {
212 : PgStat_SubXactStatus *xact_state;
213 :
214 : /*
215 : * We don't bother to free any of the transactional state, since it's all
216 : * in TopTransactionContext and will go away anyway.
217 : */
218 762 : xact_state = pgStatXactStack;
219 762 : if (xact_state != NULL)
220 : {
221 : Assert(xact_state->nest_level == 1);
222 : Assert(xact_state->prev == NULL);
223 :
224 748 : PostPrepare_PgStat_Relations(xact_state);
225 : }
226 762 : pgStatXactStack = NULL;
227 :
228 : /* Make sure any stats snapshot is thrown away */
229 762 : pgstat_clear_snapshot();
230 762 : }
231 :
232 : /*
233 : * Ensure (sub)transaction stack entry for the given nest_level exists, adding
234 : * it if needed.
235 : */
236 : PgStat_SubXactStatus *
237 753278 : pgstat_get_xact_stack_level(int nest_level)
238 : {
239 : PgStat_SubXactStatus *xact_state;
240 :
241 753278 : xact_state = pgStatXactStack;
242 753278 : if (xact_state == NULL || xact_state->nest_level != nest_level)
243 : {
244 : xact_state = (PgStat_SubXactStatus *)
245 202990 : MemoryContextAlloc(TopTransactionContext,
246 : sizeof(PgStat_SubXactStatus));
247 202990 : dclist_init(&xact_state->pending_drops);
248 202990 : xact_state->nest_level = nest_level;
249 202990 : xact_state->prev = pgStatXactStack;
250 202990 : xact_state->first = NULL;
251 202990 : pgStatXactStack = xact_state;
252 : }
253 753278 : return xact_state;
254 : }
255 :
256 : /*
257 : * Get stat items that need to be dropped at commit / abort.
258 : *
259 : * When committing, stats for objects that have been dropped in the
260 : * transaction are returned. When aborting, stats for newly created objects are
261 : * returned.
262 : *
263 : * Used by COMMIT / ABORT and 2PC PREPARE processing when building their
264 : * respective WAL records, to ensure stats are dropped in case of a crash / on
265 : * standbys.
266 : *
267 : * The list of items is allocated in CurrentMemoryContext and must be freed by
268 : * the caller (directly or via memory context reset).
269 : */
270 : int
271 481934 : pgstat_get_transactional_drops(bool isCommit, xl_xact_stats_item **items)
272 : {
273 481934 : PgStat_SubXactStatus *xact_state = pgStatXactStack;
274 481934 : int nitems = 0;
275 : dlist_iter iter;
276 :
277 481934 : if (xact_state == NULL)
278 283574 : return 0;
279 :
280 : /*
281 : * We expect to be called for subtransaction abort (which logs a WAL
282 : * record), but not for subtransaction commit (which doesn't).
283 : */
284 : Assert(!isCommit || xact_state->nest_level == 1);
285 : Assert(!isCommit || xact_state->prev == NULL);
286 :
287 198360 : *items = palloc(dclist_count(&xact_state->pending_drops)
288 : * sizeof(xl_xact_stats_item));
289 :
290 385006 : dclist_foreach(iter, &xact_state->pending_drops)
291 : {
292 186646 : PgStat_PendingDroppedStatsItem *pending =
293 186646 : dclist_container(PgStat_PendingDroppedStatsItem, node, iter.cur);
294 :
295 186646 : if (isCommit && pending->is_create)
296 115458 : continue;
297 71188 : if (!isCommit && !pending->is_create)
298 882 : continue;
299 :
300 : Assert(nitems < dclist_count(&xact_state->pending_drops));
301 70306 : (*items)[nitems++] = pending->item;
302 : }
303 :
304 198360 : return nitems;
305 : }
306 :
307 : /*
308 : * Execute scheduled drops post-commit. Called from xact_redo_commit() /
309 : * xact_redo_abort() during recovery, and from FinishPreparedTransaction()
310 : * during normal 2PC COMMIT/ABORT PREPARED processing.
311 : */
312 : void
313 5942 : pgstat_execute_transactional_drops(int ndrops, struct xl_xact_stats_item *items, bool is_redo)
314 : {
315 5942 : int not_freed_count = 0;
316 :
317 5942 : if (ndrops == 0)
318 752 : return;
319 :
320 20678 : for (int i = 0; i < ndrops; i++)
321 : {
322 15488 : xl_xact_stats_item *it = &items[i];
323 :
324 15488 : if (!pgstat_drop_entry(it->kind, it->dboid, it->objoid))
325 4 : not_freed_count++;
326 : }
327 :
328 5190 : if (not_freed_count > 0)
329 4 : pgstat_request_entry_refs_gc();
330 : }
331 :
332 : static void
333 185270 : create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, Oid objoid, bool is_create)
334 : {
335 185270 : int nest_level = GetCurrentTransactionNestLevel();
336 : PgStat_SubXactStatus *xact_state;
337 : PgStat_PendingDroppedStatsItem *drop = (PgStat_PendingDroppedStatsItem *)
338 185270 : MemoryContextAlloc(TopTransactionContext, sizeof(PgStat_PendingDroppedStatsItem));
339 :
340 185270 : xact_state = pgstat_get_xact_stack_level(nest_level);
341 :
342 185270 : drop->is_create = is_create;
343 185270 : drop->item.kind = kind;
344 185270 : drop->item.dboid = dboid;
345 185270 : drop->item.objoid = objoid;
346 :
347 185270 : dclist_push_tail(&xact_state->pending_drops, &drop->node);
348 185270 : }
349 :
350 : /*
351 : * Create a stats entry for a newly created database object in a transactional
352 : * manner.
353 : *
354 : * I.e. if the current (sub-)transaction aborts, the stats entry will also be
355 : * dropped.
356 : */
357 : void
358 119162 : pgstat_create_transactional(PgStat_Kind kind, Oid dboid, Oid objoid)
359 : {
360 119162 : if (pgstat_get_entry_ref(kind, dboid, objoid, false, NULL))
361 : {
362 0 : ereport(WARNING,
363 : errmsg("resetting existing statistics for kind %s, db=%u, oid=%u",
364 : (pgstat_get_kind_info(kind))->name, dboid, objoid));
365 :
366 0 : pgstat_reset(kind, dboid, objoid);
367 : }
368 :
369 119162 : create_drop_transactional_internal(kind, dboid, objoid, /* create */ true);
370 119162 : }
371 :
372 : /*
373 : * Drop a stats entry for a just dropped database object in a transactional
374 : * manner.
375 : *
376 : * I.e. if the current (sub-)transaction aborts, the stats entry will stay
377 : * alive.
378 : */
379 : void
380 66108 : pgstat_drop_transactional(PgStat_Kind kind, Oid dboid, Oid objoid)
381 : {
382 66108 : create_drop_transactional_internal(kind, dboid, objoid, /* create */ false);
383 66108 : }
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