Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * aio.c
4 : * AIO - Core Logic
5 : *
6 : * For documentation about how AIO works on a higher level, including a
7 : * schematic example, see README.md.
8 : *
9 : *
10 : * AIO is a complicated subsystem. To keep things navigable, it is split
11 : * across a number of files:
12 : *
13 : * - method_*.c - different ways of executing AIO (e.g. worker process)
14 : *
15 : * - aio_target.c - IO on different kinds of targets
16 : *
17 : * - aio_io.c - method-independent code for specific IO ops (e.g. readv)
18 : *
19 : * - aio_callback.c - callbacks at IO operation lifecycle events
20 : *
21 : * - aio_init.c - per-server and per-backend initialization
22 : *
23 : * - aio.c - all other topics
24 : *
25 : * - read_stream.c - helper for reading buffered relation data
26 : *
27 : * - README.md - higher-level overview over AIO
28 : *
29 : *
30 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
31 : * Portions Copyright (c) 1994, Regents of the University of California
32 : *
33 : * IDENTIFICATION
34 : * src/backend/storage/aio/aio.c
35 : *
36 : *-------------------------------------------------------------------------
37 : */
38 :
39 : #include "postgres.h"
40 :
41 : #include "lib/ilist.h"
42 : #include "miscadmin.h"
43 : #include "port/atomics.h"
44 : #include "storage/aio.h"
45 : #include "storage/aio_internal.h"
46 : #include "storage/aio_subsys.h"
47 : #include "utils/guc.h"
48 : #include "utils/guc_hooks.h"
49 : #include "utils/injection_point.h"
50 : #include "utils/resowner.h"
51 : #include "utils/wait_event_types.h"
52 :
53 :
54 : static inline void pgaio_io_update_state(PgAioHandle *ioh, PgAioHandleState new_state);
55 : static void pgaio_io_reclaim(PgAioHandle *ioh);
56 : static void pgaio_io_resowner_register(PgAioHandle *ioh);
57 : static void pgaio_io_wait_for_free(void);
58 : static PgAioHandle *pgaio_io_from_wref(PgAioWaitRef *iow, uint64 *ref_generation);
59 : static const char *pgaio_io_state_get_name(PgAioHandleState s);
60 : static void pgaio_io_wait(PgAioHandle *ioh, uint64 ref_generation);
61 :
62 :
63 : /* Options for io_method. */
64 : const struct config_enum_entry io_method_options[] = {
65 : {"sync", IOMETHOD_SYNC, false},
66 : {"worker", IOMETHOD_WORKER, false},
67 : #ifdef IOMETHOD_IO_URING_ENABLED
68 : {"io_uring", IOMETHOD_IO_URING, false},
69 : #endif
70 : {NULL, 0, false}
71 : };
72 :
73 : /* GUCs */
74 : int io_method = DEFAULT_IO_METHOD;
75 : int io_max_concurrency = -1;
76 :
77 : /* global control for AIO */
78 : PgAioCtl *pgaio_ctl;
79 :
80 : /* current backend's per-backend state */
81 : PgAioBackend *pgaio_my_backend;
82 :
83 :
84 : static const IoMethodOps *const pgaio_method_ops_table[] = {
85 : [IOMETHOD_SYNC] = &pgaio_sync_ops,
86 : [IOMETHOD_WORKER] = &pgaio_worker_ops,
87 : #ifdef IOMETHOD_IO_URING_ENABLED
88 : [IOMETHOD_IO_URING] = &pgaio_uring_ops,
89 : #endif
90 : };
91 :
92 : /* callbacks for the configured io_method, set by assign_io_method */
93 : const IoMethodOps *pgaio_method_ops;
94 :
95 :
96 : /* --------------------------------------------------------------------------------
97 : * Public Functions related to PgAioHandle
98 : * --------------------------------------------------------------------------------
99 : */
100 :
101 : /*
102 : * Acquire an AioHandle, waiting for IO completion if necessary.
103 : *
104 : * Each backend can only have one AIO handle that has been "handed out" to
105 : * code, but not yet submitted or released. This restriction is necessary to
106 : * ensure that it is possible for code to wait for an unused handle by waiting
107 : * for in-flight IO to complete. There is a limited number of handles in each
108 : * backend, if multiple handles could be handed out without being submitted,
109 : * waiting for all in-flight IO to complete would not guarantee that handles
110 : * free up.
111 : *
112 : * It is cheap to acquire an IO handle, unless all handles are in use. In that
113 : * case this function waits for the oldest IO to complete. If that is not
114 : * desirable, use pgaio_io_acquire_nb().
115 : *
116 : * If a handle was acquired but then does not turn out to be needed,
117 : * e.g. because pgaio_io_acquire() is called before starting an IO in a
118 : * critical section, the handle needs to be released with pgaio_io_release().
119 : *
120 : *
121 : * To react to the completion of the IO as soon as it is known to have
122 : * completed, callbacks can be registered with pgaio_io_register_callbacks().
123 : *
124 : * To actually execute IO using the returned handle, the pgaio_io_start_*()
125 : * family of functions is used. In many cases the pgaio_io_start_*() call will
126 : * not be done directly by code that acquired the handle, but by lower level
127 : * code that gets passed the handle. E.g. if code in bufmgr.c wants to perform
128 : * AIO, it typically will pass the handle to smgr.c, which will pass it on to
129 : * md.c, on to fd.c, which then finally calls pgaio_io_start_*(). This
130 : * forwarding allows the various layers to react to the IO's completion by
131 : * registering callbacks. These callbacks in turn can translate a lower
132 : * layer's result into a result understandable by a higher layer.
133 : *
134 : * During pgaio_io_start_*() the IO is staged (i.e. prepared for execution but
135 : * not submitted to the kernel). Unless in batchmode
136 : * (c.f. pgaio_enter_batchmode()), the IO will also get submitted for
137 : * execution. Note that, whether in batchmode or not, the IO might even
138 : * complete before the functions return.
139 : *
140 : * After pgaio_io_start_*() the AioHandle is "consumed" and may not be
141 : * referenced by the IO issuing code. To e.g. wait for IO, references to the
142 : * IO can be established with pgaio_io_get_wref() *before* pgaio_io_start_*()
143 : * is called. pgaio_wref_wait() can be used to wait for the IO to complete.
144 : *
145 : *
146 : * To know if the IO [partially] succeeded or failed, a PgAioReturn * can be
147 : * passed to pgaio_io_acquire(). Once the issuing backend has called
148 : * pgaio_wref_wait(), the PgAioReturn contains information about whether the
149 : * operation succeeded and details about the first failure, if any. The error
150 : * can be raised / logged with pgaio_result_report().
151 : *
152 : * The lifetime of the memory pointed to be *ret needs to be at least as long
153 : * as the passed in resowner. If the resowner releases resources before the IO
154 : * completes (typically due to an error), the reference to *ret will be
155 : * cleared. In case of resowner cleanup *ret will not be updated with the
156 : * results of the IO operation.
157 : */
158 : PgAioHandle *
159 5596 : pgaio_io_acquire(struct ResourceOwnerData *resowner, PgAioReturn *ret)
160 : {
161 : PgAioHandle *h;
162 :
163 : while (true)
164 : {
165 10992 : h = pgaio_io_acquire_nb(resowner, ret);
166 :
167 10988 : if (h != NULL)
168 5592 : return h;
169 :
170 : /*
171 : * Evidently all handles by this backend are in use. Just wait for
172 : * some to complete.
173 : */
174 5396 : pgaio_io_wait_for_free();
175 : }
176 : }
177 :
178 : /*
179 : * Acquire an AioHandle, returning NULL if no handles are free.
180 : *
181 : * See pgaio_io_acquire(). The only difference is that this function will return
182 : * NULL if there are no idle handles, instead of blocking.
183 : */
184 : PgAioHandle *
185 2440118 : pgaio_io_acquire_nb(struct ResourceOwnerData *resowner, PgAioReturn *ret)
186 : {
187 2440118 : PgAioHandle *ioh = NULL;
188 :
189 2440118 : if (pgaio_my_backend->num_staged_ios >= PGAIO_SUBMIT_BATCH_SIZE)
190 : {
191 : Assert(pgaio_my_backend->num_staged_ios == PGAIO_SUBMIT_BATCH_SIZE);
192 0 : pgaio_submit_staged();
193 : }
194 :
195 2440118 : if (pgaio_my_backend->handed_out_io)
196 4 : elog(ERROR, "API violation: Only one IO can be handed out");
197 :
198 : /*
199 : * Probably not needed today, as interrupts should not process this IO,
200 : * but...
201 : */
202 2440114 : HOLD_INTERRUPTS();
203 :
204 2440114 : if (!dclist_is_empty(&pgaio_my_backend->idle_ios))
205 : {
206 2429322 : dlist_node *ion = dclist_pop_head_node(&pgaio_my_backend->idle_ios);
207 :
208 2429322 : ioh = dclist_container(PgAioHandle, node, ion);
209 :
210 : Assert(ioh->state == PGAIO_HS_IDLE);
211 : Assert(ioh->owner_procno == MyProcNumber);
212 :
213 2429322 : pgaio_io_update_state(ioh, PGAIO_HS_HANDED_OUT);
214 2429322 : pgaio_my_backend->handed_out_io = ioh;
215 :
216 2429322 : if (resowner)
217 2429322 : pgaio_io_resowner_register(ioh);
218 :
219 2429322 : if (ret)
220 : {
221 2429270 : ioh->report_return = ret;
222 2429270 : ret->result.status = PGAIO_RS_UNKNOWN;
223 : }
224 : }
225 :
226 2440114 : RESUME_INTERRUPTS();
227 :
228 2440114 : return ioh;
229 : }
230 :
231 : /*
232 : * Release IO handle that turned out to not be required.
233 : *
234 : * See pgaio_io_acquire() for more details.
235 : */
236 : void
237 15150 : pgaio_io_release(PgAioHandle *ioh)
238 : {
239 15150 : if (ioh == pgaio_my_backend->handed_out_io)
240 : {
241 : Assert(ioh->state == PGAIO_HS_HANDED_OUT);
242 : Assert(ioh->resowner);
243 :
244 15146 : pgaio_my_backend->handed_out_io = NULL;
245 :
246 : /*
247 : * Note that no interrupts are processed between the handed_out_io
248 : * check and the call to reclaim - that's important as otherwise an
249 : * interrupt could have already reclaimed the handle.
250 : */
251 15146 : pgaio_io_reclaim(ioh);
252 : }
253 : else
254 : {
255 4 : elog(ERROR, "release in unexpected state");
256 : }
257 15146 : }
258 :
259 : /*
260 : * Release IO handle during resource owner cleanup.
261 : */
262 : void
263 94 : pgaio_io_release_resowner(dlist_node *ioh_node, bool on_error)
264 : {
265 94 : PgAioHandle *ioh = dlist_container(PgAioHandle, resowner_node, ioh_node);
266 :
267 : Assert(ioh->resowner);
268 :
269 : /*
270 : * Otherwise an interrupt, in the middle of releasing the IO, could end up
271 : * trying to wait for the IO, leading to state confusion.
272 : */
273 94 : HOLD_INTERRUPTS();
274 :
275 94 : ResourceOwnerForgetAioHandle(ioh->resowner, &ioh->resowner_node);
276 94 : ioh->resowner = NULL;
277 :
278 94 : switch (ioh->state)
279 : {
280 0 : case PGAIO_HS_IDLE:
281 0 : elog(ERROR, "unexpected");
282 : break;
283 66 : case PGAIO_HS_HANDED_OUT:
284 : Assert(ioh == pgaio_my_backend->handed_out_io || pgaio_my_backend->handed_out_io == NULL);
285 :
286 66 : if (ioh == pgaio_my_backend->handed_out_io)
287 : {
288 66 : pgaio_my_backend->handed_out_io = NULL;
289 66 : if (!on_error)
290 20 : elog(WARNING, "leaked AIO handle");
291 : }
292 :
293 66 : pgaio_io_reclaim(ioh);
294 66 : break;
295 0 : case PGAIO_HS_DEFINED:
296 : case PGAIO_HS_STAGED:
297 0 : if (!on_error)
298 0 : elog(WARNING, "AIO handle was not submitted");
299 0 : pgaio_submit_staged();
300 0 : break;
301 28 : case PGAIO_HS_SUBMITTED:
302 : case PGAIO_HS_COMPLETED_IO:
303 : case PGAIO_HS_COMPLETED_SHARED:
304 : case PGAIO_HS_COMPLETED_LOCAL:
305 : /* this is expected to happen */
306 28 : break;
307 : }
308 :
309 : /*
310 : * Need to unregister the reporting of the IO's result, the memory it's
311 : * referencing likely has gone away.
312 : */
313 94 : if (ioh->report_return)
314 28 : ioh->report_return = NULL;
315 :
316 94 : RESUME_INTERRUPTS();
317 94 : }
318 :
319 : /*
320 : * Add a [set of] flags to the IO.
321 : *
322 : * Note that this combines flags with already set flags, rather than set flags
323 : * to explicitly the passed in parameters. This is to allow multiple callsites
324 : * to set flags.
325 : */
326 : void
327 4825356 : pgaio_io_set_flag(PgAioHandle *ioh, PgAioHandleFlags flag)
328 : {
329 : Assert(ioh->state == PGAIO_HS_HANDED_OUT);
330 :
331 4825356 : ioh->flags |= flag;
332 4825356 : }
333 :
334 : /*
335 : * Returns an ID uniquely identifying the IO handle. This is only really
336 : * useful for logging, as handles are reused across multiple IOs.
337 : */
338 : int
339 1131294 : pgaio_io_get_id(PgAioHandle *ioh)
340 : {
341 : Assert(ioh >= pgaio_ctl->io_handles &&
342 : ioh < (pgaio_ctl->io_handles + pgaio_ctl->io_handle_count));
343 1131294 : return ioh - pgaio_ctl->io_handles;
344 : }
345 :
346 : /*
347 : * Return the ProcNumber for the process that can use an IO handle. The
348 : * mapping from IO handles to PGPROCs is static, therefore this even works
349 : * when the corresponding PGPROC is not in use.
350 : */
351 : ProcNumber
352 0 : pgaio_io_get_owner(PgAioHandle *ioh)
353 : {
354 0 : return ioh->owner_procno;
355 : }
356 :
357 : /*
358 : * Return a wait reference for the IO. Only wait references can be used to
359 : * wait for an IOs completion, as handles themselves can be reused after
360 : * completion. See also the comment above pgaio_io_acquire().
361 : */
362 : void
363 4828250 : pgaio_io_get_wref(PgAioHandle *ioh, PgAioWaitRef *iow)
364 : {
365 : Assert(ioh->state == PGAIO_HS_HANDED_OUT ||
366 : ioh->state == PGAIO_HS_DEFINED ||
367 : ioh->state == PGAIO_HS_STAGED);
368 : Assert(ioh->generation != 0);
369 :
370 4828250 : iow->aio_index = ioh - pgaio_ctl->io_handles;
371 4828250 : iow->generation_upper = (uint32) (ioh->generation >> 32);
372 4828250 : iow->generation_lower = (uint32) ioh->generation;
373 4828250 : }
374 :
375 :
376 :
377 : /* --------------------------------------------------------------------------------
378 : * Internal Functions related to PgAioHandle
379 : * --------------------------------------------------------------------------------
380 : */
381 :
382 : static inline void
383 18926064 : pgaio_io_update_state(PgAioHandle *ioh, PgAioHandleState new_state)
384 : {
385 : /*
386 : * All callers need to have held interrupts in some form, otherwise
387 : * interrupt processing could wait for the IO to complete, while in an
388 : * intermediary state.
389 : */
390 : Assert(!INTERRUPTS_CAN_BE_PROCESSED());
391 :
392 18926064 : pgaio_debug_io(DEBUG5, ioh,
393 : "updating state to %s",
394 : pgaio_io_state_get_name(new_state));
395 :
396 : /*
397 : * Ensure the changes signified by the new state are visible before the
398 : * new state becomes visible.
399 : */
400 18926064 : pg_write_barrier();
401 :
402 18926064 : ioh->state = new_state;
403 18926064 : }
404 :
405 : static void
406 2429322 : pgaio_io_resowner_register(PgAioHandle *ioh)
407 : {
408 : Assert(!ioh->resowner);
409 : Assert(CurrentResourceOwner);
410 :
411 2429322 : ResourceOwnerRememberAioHandle(CurrentResourceOwner, &ioh->resowner_node);
412 2429322 : ioh->resowner = CurrentResourceOwner;
413 2429322 : }
414 :
415 : /*
416 : * Stage IO for execution and, if appropriate, submit it immediately.
417 : *
418 : * Should only be called from pgaio_io_start_*().
419 : */
420 : void
421 2414110 : pgaio_io_stage(PgAioHandle *ioh, PgAioOp op)
422 : {
423 : bool needs_synchronous;
424 :
425 : Assert(ioh->state == PGAIO_HS_HANDED_OUT);
426 : Assert(pgaio_my_backend->handed_out_io == ioh);
427 : Assert(pgaio_io_has_target(ioh));
428 :
429 : /*
430 : * Otherwise an interrupt, in the middle of staging and possibly executing
431 : * the IO, could end up trying to wait for the IO, leading to state
432 : * confusion.
433 : */
434 2414110 : HOLD_INTERRUPTS();
435 :
436 2414110 : ioh->op = op;
437 2414110 : ioh->result = 0;
438 :
439 2414110 : pgaio_io_update_state(ioh, PGAIO_HS_DEFINED);
440 :
441 : /* allow a new IO to be staged */
442 2414110 : pgaio_my_backend->handed_out_io = NULL;
443 :
444 2414110 : pgaio_io_call_stage(ioh);
445 :
446 2414110 : pgaio_io_update_state(ioh, PGAIO_HS_STAGED);
447 :
448 : /*
449 : * Synchronous execution has to be executed, well, synchronously, so check
450 : * that first.
451 : */
452 2414110 : needs_synchronous = pgaio_io_needs_synchronous_execution(ioh);
453 :
454 2414110 : pgaio_debug_io(DEBUG3, ioh,
455 : "staged (synchronous: %d, in_batch: %d)",
456 : needs_synchronous, pgaio_my_backend->in_batchmode);
457 :
458 2414110 : if (!needs_synchronous)
459 : {
460 1073476 : pgaio_my_backend->staged_ios[pgaio_my_backend->num_staged_ios++] = ioh;
461 : Assert(pgaio_my_backend->num_staged_ios <= PGAIO_SUBMIT_BATCH_SIZE);
462 :
463 : /*
464 : * Unless code explicitly opted into batching IOs, submit the IO
465 : * immediately.
466 : */
467 1073476 : if (!pgaio_my_backend->in_batchmode)
468 52052 : pgaio_submit_staged();
469 : }
470 : else
471 : {
472 1340634 : pgaio_io_prepare_submit(ioh);
473 1340634 : pgaio_io_perform_synchronously(ioh);
474 : }
475 :
476 2414110 : RESUME_INTERRUPTS();
477 2414110 : }
478 :
479 : bool
480 2414110 : pgaio_io_needs_synchronous_execution(PgAioHandle *ioh)
481 : {
482 : /*
483 : * If the caller said to execute the IO synchronously, do so.
484 : *
485 : * XXX: We could optimize the logic when to execute synchronously by first
486 : * checking if there are other IOs in flight and only synchronously
487 : * executing if not. Unclear whether that'll be sufficiently common to be
488 : * worth worrying about.
489 : */
490 2414110 : if (ioh->flags & PGAIO_HF_SYNCHRONOUS)
491 1332510 : return true;
492 :
493 : /* Check if the IO method requires synchronous execution of IO */
494 1081600 : if (pgaio_method_ops->needs_synchronous_execution)
495 1081600 : return pgaio_method_ops->needs_synchronous_execution(ioh);
496 :
497 0 : return false;
498 : }
499 :
500 : /*
501 : * Handle IO being processed by IO method.
502 : *
503 : * Should be called by IO methods / synchronous IO execution, just before the
504 : * IO is performed.
505 : */
506 : void
507 2414110 : pgaio_io_prepare_submit(PgAioHandle *ioh)
508 : {
509 2414110 : pgaio_io_update_state(ioh, PGAIO_HS_SUBMITTED);
510 :
511 2414110 : dclist_push_tail(&pgaio_my_backend->in_flight_ios, &ioh->node);
512 2414110 : }
513 :
514 : /*
515 : * Handle IO getting completed by a method.
516 : *
517 : * Should be called by IO methods / synchronous IO execution, just after the
518 : * IO has been performed.
519 : *
520 : * Expects to be called in a critical section. We expect IOs to be usable for
521 : * WAL etc, which requires being able to execute completion callbacks in a
522 : * critical section.
523 : */
524 : void
525 2205490 : pgaio_io_process_completion(PgAioHandle *ioh, int result)
526 : {
527 : Assert(ioh->state == PGAIO_HS_SUBMITTED);
528 :
529 : Assert(CritSectionCount > 0);
530 :
531 2205490 : ioh->result = result;
532 :
533 2205490 : pgaio_io_update_state(ioh, PGAIO_HS_COMPLETED_IO);
534 :
535 2205490 : INJECTION_POINT("aio-process-completion-before-shared", ioh);
536 :
537 2205490 : pgaio_io_call_complete_shared(ioh);
538 :
539 2205490 : pgaio_io_update_state(ioh, PGAIO_HS_COMPLETED_SHARED);
540 :
541 : /* condition variable broadcast ensures state is visible before wakeup */
542 2205490 : ConditionVariableBroadcast(&ioh->cv);
543 :
544 : /* contains call to pgaio_io_call_complete_local() */
545 2205490 : if (ioh->owner_procno == MyProcNumber)
546 1340634 : pgaio_io_reclaim(ioh);
547 2205490 : }
548 :
549 : /*
550 : * Has the IO completed and thus the IO handle been reused?
551 : *
552 : * This is useful when waiting for IO completion at a low level (e.g. in an IO
553 : * method's ->wait_one() callback).
554 : */
555 : bool
556 3000480 : pgaio_io_was_recycled(PgAioHandle *ioh, uint64 ref_generation, PgAioHandleState *state)
557 : {
558 3000480 : *state = ioh->state;
559 :
560 : /*
561 : * Ensure that we don't see an earlier state of the handle than ioh->state
562 : * due to compiler or CPU reordering. This protects both ->generation as
563 : * directly used here, and other fields in the handle accessed in the
564 : * caller if the handle was not reused.
565 : */
566 3000480 : pg_read_barrier();
567 :
568 3000480 : return ioh->generation != ref_generation;
569 : }
570 :
571 : /*
572 : * Wait for IO to complete. External code should never use this, outside of
573 : * the AIO subsystem waits are only allowed via pgaio_wref_wait().
574 : */
575 : static void
576 387126 : pgaio_io_wait(PgAioHandle *ioh, uint64 ref_generation)
577 : {
578 : PgAioHandleState state;
579 : bool am_owner;
580 :
581 387126 : am_owner = ioh->owner_procno == MyProcNumber;
582 :
583 387126 : if (pgaio_io_was_recycled(ioh, ref_generation, &state))
584 68 : return;
585 :
586 387058 : if (am_owner)
587 : {
588 375208 : if (state != PGAIO_HS_SUBMITTED
589 87172 : && state != PGAIO_HS_COMPLETED_IO
590 454 : && state != PGAIO_HS_COMPLETED_SHARED
591 0 : && state != PGAIO_HS_COMPLETED_LOCAL)
592 : {
593 0 : elog(PANIC, "waiting for own IO %d in wrong state: %s",
594 : pgaio_io_get_id(ioh), pgaio_io_get_state_name(ioh));
595 : }
596 : }
597 :
598 : while (true)
599 : {
600 773478 : if (pgaio_io_was_recycled(ioh, ref_generation, &state))
601 8592 : return;
602 :
603 764886 : switch (state)
604 : {
605 0 : case PGAIO_HS_IDLE:
606 : case PGAIO_HS_HANDED_OUT:
607 0 : elog(ERROR, "IO in wrong state: %d", state);
608 : break;
609 :
610 294450 : case PGAIO_HS_SUBMITTED:
611 :
612 : /*
613 : * If we need to wait via the IO method, do so now. Don't
614 : * check via the IO method if the issuing backend is executing
615 : * the IO synchronously.
616 : */
617 294450 : if (pgaio_method_ops->wait_one && !(ioh->flags & PGAIO_HF_SYNCHRONOUS))
618 : {
619 0 : pgaio_method_ops->wait_one(ioh, ref_generation);
620 0 : continue;
621 : }
622 : /* fallthrough */
623 :
624 : /* waiting for owner to submit */
625 : case PGAIO_HS_DEFINED:
626 : case PGAIO_HS_STAGED:
627 : /* waiting for reaper to complete */
628 : /* fallthrough */
629 : case PGAIO_HS_COMPLETED_IO:
630 : /* shouldn't be able to hit this otherwise */
631 : Assert(IsUnderPostmaster);
632 : /* ensure we're going to get woken up */
633 386420 : ConditionVariablePrepareToSleep(&ioh->cv);
634 :
635 771848 : while (!pgaio_io_was_recycled(ioh, ref_generation, &state))
636 : {
637 763298 : if (state == PGAIO_HS_COMPLETED_SHARED ||
638 385494 : state == PGAIO_HS_COMPLETED_LOCAL)
639 : break;
640 385428 : ConditionVariableSleep(&ioh->cv, WAIT_EVENT_AIO_IO_COMPLETION);
641 : }
642 :
643 386420 : ConditionVariableCancelSleep();
644 386420 : break;
645 :
646 378466 : case PGAIO_HS_COMPLETED_SHARED:
647 : case PGAIO_HS_COMPLETED_LOCAL:
648 :
649 : /*
650 : * Note that no interrupts are processed between
651 : * pgaio_io_was_recycled() and this check - that's important
652 : * as otherwise an interrupt could have already reclaimed the
653 : * handle.
654 : */
655 378466 : if (am_owner)
656 375208 : pgaio_io_reclaim(ioh);
657 378466 : return;
658 : }
659 : }
660 : }
661 :
662 : /*
663 : * Make IO handle ready to be reused after IO has completed or after the
664 : * handle has been released without being used.
665 : *
666 : * Note that callers need to be careful about only calling this in the right
667 : * state and that no interrupts can be processed between the state check and
668 : * the call to pgaio_io_reclaim(). Otherwise interrupt processing could
669 : * already have reclaimed the handle.
670 : */
671 : static void
672 2429322 : pgaio_io_reclaim(PgAioHandle *ioh)
673 : {
674 : /* This is only ok if it's our IO */
675 : Assert(ioh->owner_procno == MyProcNumber);
676 : Assert(ioh->state != PGAIO_HS_IDLE);
677 :
678 : /* see comment in function header */
679 2429322 : HOLD_INTERRUPTS();
680 :
681 : /*
682 : * It's a bit ugly, but right now the easiest place to put the execution
683 : * of local completion callbacks is this function, as we need to execute
684 : * local callbacks just before reclaiming at multiple callsites.
685 : */
686 2429322 : if (ioh->state == PGAIO_HS_COMPLETED_SHARED)
687 : {
688 : PgAioResult local_result;
689 :
690 2414110 : local_result = pgaio_io_call_complete_local(ioh);
691 2414110 : pgaio_io_update_state(ioh, PGAIO_HS_COMPLETED_LOCAL);
692 :
693 2414110 : if (ioh->report_return)
694 : {
695 2414082 : ioh->report_return->result = local_result;
696 2414082 : ioh->report_return->target_data = ioh->target_data;
697 : }
698 : }
699 :
700 2429322 : pgaio_debug_io(DEBUG4, ioh,
701 : "reclaiming: distilled_result: (status %s, id %u, error_data %d), raw_result: %d",
702 : pgaio_result_status_string(ioh->distilled_result.status),
703 : ioh->distilled_result.id,
704 : ioh->distilled_result.error_data,
705 : ioh->result);
706 :
707 : /* if the IO has been defined, it's on the in-flight list, remove */
708 2429322 : if (ioh->state != PGAIO_HS_HANDED_OUT)
709 2414110 : dclist_delete_from(&pgaio_my_backend->in_flight_ios, &ioh->node);
710 :
711 2429322 : if (ioh->resowner)
712 : {
713 2429228 : ResourceOwnerForgetAioHandle(ioh->resowner, &ioh->resowner_node);
714 2429228 : ioh->resowner = NULL;
715 : }
716 :
717 : Assert(!ioh->resowner);
718 :
719 : /*
720 : * Update generation & state first, before resetting the IO's fields,
721 : * otherwise a concurrent "viewer" could think the fields are valid, even
722 : * though they are being reset. Increment the generation first, so that
723 : * we can assert elsewhere that we never wait for an IDLE IO. While it's
724 : * a bit weird for the state to go backwards for a generation, it's OK
725 : * here, as there cannot be references to the "reborn" IO yet. Can't
726 : * update both at once, so something has to give.
727 : */
728 2429322 : ioh->generation++;
729 2429322 : pgaio_io_update_state(ioh, PGAIO_HS_IDLE);
730 :
731 : /* ensure the state update is visible before we reset fields */
732 2429322 : pg_write_barrier();
733 :
734 2429322 : ioh->op = PGAIO_OP_INVALID;
735 2429322 : ioh->target = PGAIO_TID_INVALID;
736 2429322 : ioh->flags = 0;
737 2429322 : ioh->num_callbacks = 0;
738 2429322 : ioh->handle_data_len = 0;
739 2429322 : ioh->report_return = NULL;
740 2429322 : ioh->result = 0;
741 2429322 : ioh->distilled_result.status = PGAIO_RS_UNKNOWN;
742 :
743 : /*
744 : * We push the IO to the head of the idle IO list, that seems more cache
745 : * efficient in cases where only a few IOs are used.
746 : */
747 2429322 : dclist_push_head(&pgaio_my_backend->idle_ios, &ioh->node);
748 :
749 2429322 : RESUME_INTERRUPTS();
750 2429322 : }
751 :
752 : /*
753 : * Wait for an IO handle to become usable.
754 : *
755 : * This only really is useful for pgaio_io_acquire().
756 : */
757 : static void
758 5396 : pgaio_io_wait_for_free(void)
759 : {
760 5396 : int reclaimed = 0;
761 :
762 5396 : pgaio_debug(DEBUG2, "waiting for free IO with %d pending, %u in-flight, %u idle IOs",
763 : pgaio_my_backend->num_staged_ios,
764 : dclist_count(&pgaio_my_backend->in_flight_ios),
765 : dclist_count(&pgaio_my_backend->idle_ios));
766 :
767 : /*
768 : * First check if any of our IOs actually have completed - when using
769 : * worker, that'll often be the case. We could do so as part of the loop
770 : * below, but that'd potentially lead us to wait for some IO submitted
771 : * before.
772 : */
773 10792 : for (int i = 0; i < io_max_concurrency; i++)
774 : {
775 5396 : PgAioHandle *ioh = &pgaio_ctl->io_handles[pgaio_my_backend->io_handle_off + i];
776 :
777 5396 : if (ioh->state == PGAIO_HS_COMPLETED_SHARED)
778 : {
779 : /*
780 : * Note that no interrupts are processed between the state check
781 : * and the call to reclaim - that's important as otherwise an
782 : * interrupt could have already reclaimed the handle.
783 : *
784 : * Need to ensure that there's no reordering, in the more common
785 : * paths, where we wait for IO, that's done by
786 : * pgaio_io_was_recycled().
787 : */
788 4474 : pg_read_barrier();
789 4474 : pgaio_io_reclaim(ioh);
790 4474 : reclaimed++;
791 : }
792 : }
793 :
794 5396 : if (reclaimed > 0)
795 4474 : return;
796 :
797 : /*
798 : * If we have any unsubmitted IOs, submit them now. We'll start waiting in
799 : * a second, so it's better they're in flight. This also addresses the
800 : * edge-case that all IOs are unsubmitted.
801 : */
802 922 : if (pgaio_my_backend->num_staged_ios > 0)
803 0 : pgaio_submit_staged();
804 :
805 : /* possibly some IOs finished during submission */
806 922 : if (!dclist_is_empty(&pgaio_my_backend->idle_ios))
807 0 : return;
808 :
809 922 : if (dclist_count(&pgaio_my_backend->in_flight_ios) == 0)
810 0 : ereport(ERROR,
811 : errmsg_internal("no free IOs despite no in-flight IOs"),
812 : errdetail_internal("%d pending, %u in-flight, %u idle IOs",
813 : pgaio_my_backend->num_staged_ios,
814 : dclist_count(&pgaio_my_backend->in_flight_ios),
815 : dclist_count(&pgaio_my_backend->idle_ios)));
816 :
817 : /*
818 : * Wait for the oldest in-flight IO to complete.
819 : *
820 : * XXX: Reusing the general IO wait is suboptimal, we don't need to wait
821 : * for that specific IO to complete, we just need *any* IO to complete.
822 : */
823 : {
824 922 : PgAioHandle *ioh = dclist_head_element(PgAioHandle, node,
825 : &pgaio_my_backend->in_flight_ios);
826 922 : uint64 generation = ioh->generation;
827 :
828 922 : switch (ioh->state)
829 : {
830 : /* should not be in in-flight list */
831 0 : case PGAIO_HS_IDLE:
832 : case PGAIO_HS_DEFINED:
833 : case PGAIO_HS_HANDED_OUT:
834 : case PGAIO_HS_STAGED:
835 : case PGAIO_HS_COMPLETED_LOCAL:
836 0 : elog(ERROR, "shouldn't get here with io:%d in state %d",
837 : pgaio_io_get_id(ioh), ioh->state);
838 : break;
839 :
840 920 : case PGAIO_HS_COMPLETED_IO:
841 : case PGAIO_HS_SUBMITTED:
842 920 : pgaio_debug_io(DEBUG2, ioh,
843 : "waiting for free io with %u in flight",
844 : dclist_count(&pgaio_my_backend->in_flight_ios));
845 :
846 : /*
847 : * In a more general case this would be racy, because the
848 : * generation could increase after we read ioh->state above.
849 : * But we are only looking at IOs by the current backend and
850 : * the IO can only be recycled by this backend. Even this is
851 : * only OK because we get the handle's generation before
852 : * potentially processing interrupts, e.g. as part of
853 : * pgaio_debug_io().
854 : */
855 920 : pgaio_io_wait(ioh, generation);
856 920 : break;
857 :
858 2 : case PGAIO_HS_COMPLETED_SHARED:
859 :
860 : /*
861 : * It's possible that another backend just finished this IO.
862 : *
863 : * Note that no interrupts are processed between the state
864 : * check and the call to reclaim - that's important as
865 : * otherwise an interrupt could have already reclaimed the
866 : * handle.
867 : *
868 : * Need to ensure that there's no reordering, in the more
869 : * common paths, where we wait for IO, that's done by
870 : * pgaio_io_was_recycled().
871 : */
872 2 : pg_read_barrier();
873 2 : pgaio_io_reclaim(ioh);
874 2 : break;
875 : }
876 :
877 922 : if (dclist_count(&pgaio_my_backend->idle_ios) == 0)
878 0 : elog(PANIC, "no idle IO after waiting for IO to terminate");
879 922 : return;
880 : }
881 : }
882 :
883 : /*
884 : * Internal - code outside of AIO should never need this and it'd be hard for
885 : * such code to be safe.
886 : */
887 : static PgAioHandle *
888 1454216 : pgaio_io_from_wref(PgAioWaitRef *iow, uint64 *ref_generation)
889 : {
890 : PgAioHandle *ioh;
891 :
892 : Assert(iow->aio_index < pgaio_ctl->io_handle_count);
893 :
894 1454216 : ioh = &pgaio_ctl->io_handles[iow->aio_index];
895 :
896 1454216 : *ref_generation = ((uint64) iow->generation_upper) << 32 |
897 1454216 : iow->generation_lower;
898 :
899 : Assert(*ref_generation != 0);
900 :
901 1454216 : return ioh;
902 : }
903 :
904 : static const char *
905 14382 : pgaio_io_state_get_name(PgAioHandleState s)
906 : {
907 : #define PGAIO_HS_TOSTR_CASE(sym) case PGAIO_HS_##sym: return #sym
908 14382 : switch (s)
909 : {
910 0 : PGAIO_HS_TOSTR_CASE(IDLE);
911 4764 : PGAIO_HS_TOSTR_CASE(HANDED_OUT);
912 2382 : PGAIO_HS_TOSTR_CASE(DEFINED);
913 2382 : PGAIO_HS_TOSTR_CASE(STAGED);
914 70 : PGAIO_HS_TOSTR_CASE(SUBMITTED);
915 2384 : PGAIO_HS_TOSTR_CASE(COMPLETED_IO);
916 2400 : PGAIO_HS_TOSTR_CASE(COMPLETED_SHARED);
917 0 : PGAIO_HS_TOSTR_CASE(COMPLETED_LOCAL);
918 : }
919 : #undef PGAIO_HS_TOSTR_CASE
920 :
921 0 : return NULL; /* silence compiler */
922 : }
923 :
924 : const char *
925 14382 : pgaio_io_get_state_name(PgAioHandle *ioh)
926 : {
927 14382 : return pgaio_io_state_get_name(ioh->state);
928 : }
929 :
930 : const char *
931 4764 : pgaio_result_status_string(PgAioResultStatus rs)
932 : {
933 4764 : switch (rs)
934 : {
935 0 : case PGAIO_RS_UNKNOWN:
936 0 : return "UNKNOWN";
937 4404 : case PGAIO_RS_OK:
938 4404 : return "OK";
939 136 : case PGAIO_RS_WARNING:
940 136 : return "WARNING";
941 40 : case PGAIO_RS_PARTIAL:
942 40 : return "PARTIAL";
943 184 : case PGAIO_RS_ERROR:
944 184 : return "ERROR";
945 : }
946 :
947 0 : return NULL; /* silence compiler */
948 : }
949 :
950 :
951 :
952 : /* --------------------------------------------------------------------------------
953 : * Functions primarily related to IO Wait References
954 : * --------------------------------------------------------------------------------
955 : */
956 :
957 : /*
958 : * Mark a wait reference as invalid
959 : */
960 : void
961 25966180 : pgaio_wref_clear(PgAioWaitRef *iow)
962 : {
963 25966180 : iow->aio_index = PG_UINT32_MAX;
964 25966180 : }
965 :
966 : /* Is the wait reference valid? */
967 : bool
968 4942866 : pgaio_wref_valid(PgAioWaitRef *iow)
969 : {
970 4942866 : return iow->aio_index != PG_UINT32_MAX;
971 : }
972 :
973 : /*
974 : * Similar to pgaio_io_get_id(), just for wait references.
975 : */
976 : int
977 0 : pgaio_wref_get_id(PgAioWaitRef *iow)
978 : {
979 : Assert(pgaio_wref_valid(iow));
980 0 : return iow->aio_index;
981 : }
982 :
983 : /*
984 : * Wait for the IO to have completed. Can be called in any process, not just
985 : * in the issuing backend.
986 : */
987 : void
988 386188 : pgaio_wref_wait(PgAioWaitRef *iow)
989 : {
990 : uint64 ref_generation;
991 : PgAioHandle *ioh;
992 :
993 386188 : ioh = pgaio_io_from_wref(iow, &ref_generation);
994 :
995 386188 : pgaio_io_wait(ioh, ref_generation);
996 386188 : }
997 :
998 : /*
999 : * Check if the referenced IO completed, without blocking.
1000 : */
1001 : bool
1002 1068028 : pgaio_wref_check_done(PgAioWaitRef *iow)
1003 : {
1004 : uint64 ref_generation;
1005 : PgAioHandleState state;
1006 : bool am_owner;
1007 : PgAioHandle *ioh;
1008 :
1009 1068028 : ioh = pgaio_io_from_wref(iow, &ref_generation);
1010 :
1011 1068028 : if (pgaio_io_was_recycled(ioh, ref_generation, &state))
1012 0 : return true;
1013 :
1014 1068028 : if (state == PGAIO_HS_IDLE)
1015 0 : return true;
1016 :
1017 1068028 : am_owner = ioh->owner_procno == MyProcNumber;
1018 :
1019 1068028 : if (state == PGAIO_HS_COMPLETED_SHARED ||
1020 374236 : state == PGAIO_HS_COMPLETED_LOCAL)
1021 : {
1022 : /*
1023 : * Note that no interrupts are processed between
1024 : * pgaio_io_was_recycled() and this check - that's important as
1025 : * otherwise an interrupt could have already reclaimed the handle.
1026 : */
1027 693792 : if (am_owner)
1028 693792 : pgaio_io_reclaim(ioh);
1029 693792 : return true;
1030 : }
1031 :
1032 : /*
1033 : * XXX: It likely would be worth checking in with the io method, to give
1034 : * the IO method a chance to check if there are completion events queued.
1035 : */
1036 :
1037 374236 : return false;
1038 : }
1039 :
1040 :
1041 :
1042 : /* --------------------------------------------------------------------------------
1043 : * Actions on multiple IOs.
1044 : * --------------------------------------------------------------------------------
1045 : */
1046 :
1047 : /*
1048 : * Submit IOs in batches going forward.
1049 : *
1050 : * Submitting multiple IOs at once can be substantially faster than doing so
1051 : * one-by-one. At the same time, submitting multiple IOs at once requires more
1052 : * care to avoid deadlocks.
1053 : *
1054 : * Consider backend A staging an IO for buffer 1 and then trying to start IO
1055 : * on buffer 2, while backend B does the inverse. If A submitted the IO before
1056 : * moving on to buffer 2, this works just fine, B will wait for the IO to
1057 : * complete. But if batching were used, each backend will wait for IO that has
1058 : * not yet been submitted to complete, i.e. forever.
1059 : *
1060 : * End batch submission mode with pgaio_exit_batchmode(). (Throwing errors is
1061 : * allowed; error recovery will end the batch.)
1062 : *
1063 : * To avoid deadlocks, code needs to ensure that it will not wait for another
1064 : * backend while there is unsubmitted IO. E.g. by using conditional lock
1065 : * acquisition when acquiring buffer locks. To check if there currently are
1066 : * staged IOs, call pgaio_have_staged() and to submit all staged IOs call
1067 : * pgaio_submit_staged().
1068 : *
1069 : * It is not allowed to enter batchmode while already in batchmode, it's
1070 : * unlikely to ever be needed, as code needs to be explicitly aware of being
1071 : * called in batchmode, to avoid the deadlock risks explained above.
1072 : *
1073 : * Note that IOs may get submitted before pgaio_exit_batchmode() is called,
1074 : * e.g. because too many IOs have been staged or because pgaio_submit_staged()
1075 : * was called.
1076 : */
1077 : void
1078 5368792 : pgaio_enter_batchmode(void)
1079 : {
1080 5368792 : if (pgaio_my_backend->in_batchmode)
1081 0 : elog(ERROR, "starting batch while batch already in progress");
1082 5368792 : pgaio_my_backend->in_batchmode = true;
1083 5368792 : }
1084 :
1085 : /*
1086 : * Stop submitting IOs in batches.
1087 : */
1088 : void
1089 5368772 : pgaio_exit_batchmode(void)
1090 : {
1091 : Assert(pgaio_my_backend->in_batchmode);
1092 :
1093 5368772 : pgaio_submit_staged();
1094 5368772 : pgaio_my_backend->in_batchmode = false;
1095 5368772 : }
1096 :
1097 : /*
1098 : * Are there staged but unsubmitted IOs?
1099 : *
1100 : * See comment above pgaio_enter_batchmode() for why code may need to check if
1101 : * there is IO in that state.
1102 : */
1103 : bool
1104 2429126 : pgaio_have_staged(void)
1105 : {
1106 : Assert(pgaio_my_backend->in_batchmode ||
1107 : pgaio_my_backend->num_staged_ios == 0);
1108 2429126 : return pgaio_my_backend->num_staged_ios > 0;
1109 : }
1110 :
1111 : /*
1112 : * Submit all staged but not yet submitted IOs.
1113 : *
1114 : * Unless in batch mode, this never needs to be called, as IOs get submitted
1115 : * as soon as possible. While in batchmode pgaio_submit_staged() can be called
1116 : * before waiting on another backend, to avoid the risk of deadlocks. See
1117 : * pgaio_enter_batchmode().
1118 : */
1119 : void
1120 5426244 : pgaio_submit_staged(void)
1121 : {
1122 5426244 : int total_submitted = 0;
1123 : int did_submit;
1124 :
1125 5426244 : if (pgaio_my_backend->num_staged_ios == 0)
1126 4353912 : return;
1127 :
1128 :
1129 1072332 : START_CRIT_SECTION();
1130 :
1131 1072332 : did_submit = pgaio_method_ops->submit(pgaio_my_backend->num_staged_ios,
1132 1072332 : pgaio_my_backend->staged_ios);
1133 :
1134 1072332 : END_CRIT_SECTION();
1135 :
1136 1072332 : total_submitted += did_submit;
1137 :
1138 : Assert(total_submitted == did_submit);
1139 :
1140 1072332 : pgaio_my_backend->num_staged_ios = 0;
1141 :
1142 1072332 : pgaio_debug(DEBUG4,
1143 : "aio: submitted %d IOs",
1144 : total_submitted);
1145 : }
1146 :
1147 :
1148 :
1149 : /* --------------------------------------------------------------------------------
1150 : * Other
1151 : * --------------------------------------------------------------------------------
1152 : */
1153 :
1154 :
1155 : /*
1156 : * Perform AIO related cleanup after an error.
1157 : *
1158 : * This should be called early in the error recovery paths, as later steps may
1159 : * need to issue AIO (e.g. to record a transaction abort WAL record).
1160 : */
1161 : void
1162 58560 : pgaio_error_cleanup(void)
1163 : {
1164 : /*
1165 : * It is possible that code errored out after pgaio_enter_batchmode() but
1166 : * before pgaio_exit_batchmode() was called. In that case we need to
1167 : * submit the IO now.
1168 : */
1169 58560 : if (pgaio_my_backend->in_batchmode)
1170 : {
1171 20 : pgaio_my_backend->in_batchmode = false;
1172 :
1173 20 : pgaio_submit_staged();
1174 : }
1175 :
1176 : /*
1177 : * As we aren't in batchmode, there shouldn't be any unsubmitted IOs.
1178 : */
1179 : Assert(pgaio_my_backend->num_staged_ios == 0);
1180 58560 : }
1181 :
1182 : /*
1183 : * Perform AIO related checks at (sub-)transactional boundaries.
1184 : *
1185 : * This should be called late during (sub-)transactional commit/abort, after
1186 : * all steps that might need to perform AIO, so that we can verify that the
1187 : * AIO subsystem is in a valid state at the end of a transaction.
1188 : */
1189 : void
1190 1123200 : AtEOXact_Aio(bool is_commit)
1191 : {
1192 : /*
1193 : * We should never be in batch mode at transactional boundaries. In case
1194 : * an error was thrown while in batch mode, pgaio_error_cleanup() should
1195 : * have exited batchmode.
1196 : *
1197 : * In case we are in batchmode somehow, make sure to submit all staged
1198 : * IOs, other backends may need them to complete to continue.
1199 : */
1200 1123200 : if (pgaio_my_backend->in_batchmode)
1201 : {
1202 8 : pgaio_error_cleanup();
1203 8 : elog(WARNING, "open AIO batch at end of (sub-)transaction");
1204 : }
1205 :
1206 : /*
1207 : * As we aren't in batchmode, there shouldn't be any unsubmitted IOs.
1208 : */
1209 : Assert(pgaio_my_backend->num_staged_ios == 0);
1210 1123200 : }
1211 :
1212 : /*
1213 : * Need to submit staged but not yet submitted IOs using the fd, otherwise
1214 : * the IO would end up targeting something bogus.
1215 : */
1216 : void
1217 16528566 : pgaio_closing_fd(int fd)
1218 : {
1219 : /*
1220 : * Might be called before AIO is initialized or in a subprocess that
1221 : * doesn't use AIO.
1222 : */
1223 16528566 : if (!pgaio_my_backend)
1224 13860 : return;
1225 :
1226 : /*
1227 : * For now just submit all staged IOs - we could be more selective, but
1228 : * it's probably not worth it.
1229 : */
1230 16514706 : if (pgaio_my_backend->num_staged_ios > 0)
1231 : {
1232 4 : pgaio_debug(DEBUG2,
1233 : "submitting %d IOs before FD %d gets closed",
1234 : pgaio_my_backend->num_staged_ios, fd);
1235 4 : pgaio_submit_staged();
1236 : }
1237 :
1238 : /*
1239 : * If requested by the IO method, wait for all IOs that use the
1240 : * to-be-closed FD.
1241 : */
1242 16514706 : if (pgaio_method_ops->wait_on_fd_before_close)
1243 : {
1244 : /*
1245 : * As waiting for one IO to complete may complete multiple IOs, we
1246 : * can't just use a mutable list iterator. The maximum number of
1247 : * in-flight IOs is fairly small, so just restart the loop after
1248 : * waiting for an IO.
1249 : */
1250 0 : while (!dclist_is_empty(&pgaio_my_backend->in_flight_ios))
1251 : {
1252 : dlist_iter iter;
1253 0 : PgAioHandle *ioh = NULL;
1254 : uint64 generation;
1255 :
1256 0 : dclist_foreach(iter, &pgaio_my_backend->in_flight_ios)
1257 : {
1258 0 : ioh = dclist_container(PgAioHandle, node, iter.cur);
1259 :
1260 0 : generation = ioh->generation;
1261 :
1262 0 : if (pgaio_io_uses_fd(ioh, fd))
1263 0 : break;
1264 : else
1265 0 : ioh = NULL;
1266 : }
1267 :
1268 0 : if (!ioh)
1269 0 : break;
1270 :
1271 0 : pgaio_debug_io(DEBUG2, ioh,
1272 : "waiting for IO before FD %d gets closed, %u in-flight IOs",
1273 : fd, dclist_count(&pgaio_my_backend->in_flight_ios));
1274 :
1275 : /* see comment in pgaio_io_wait_for_free() about raciness */
1276 0 : pgaio_io_wait(ioh, generation);
1277 : }
1278 : }
1279 : }
1280 :
1281 : /*
1282 : * Registered as before_shmem_exit() callback in pgaio_init_backend()
1283 : */
1284 : void
1285 39002 : pgaio_shutdown(int code, Datum arg)
1286 : {
1287 : Assert(pgaio_my_backend);
1288 : Assert(!pgaio_my_backend->handed_out_io);
1289 :
1290 : /* first clean up resources as we would at a transaction boundary */
1291 39002 : AtEOXact_Aio(code == 0);
1292 :
1293 : /*
1294 : * Before exiting, make sure that all IOs are finished. That has two main
1295 : * purposes:
1296 : *
1297 : * - Some kernel-level AIO mechanisms don't deal well with the issuer of
1298 : * an AIO exiting before IO completed
1299 : *
1300 : * - It'd be confusing to see partially finished IOs in stats views etc
1301 : */
1302 39020 : while (!dclist_is_empty(&pgaio_my_backend->in_flight_ios))
1303 : {
1304 18 : PgAioHandle *ioh = dclist_head_element(PgAioHandle, node, &pgaio_my_backend->in_flight_ios);
1305 18 : uint64 generation = ioh->generation;
1306 :
1307 18 : pgaio_debug_io(DEBUG2, ioh,
1308 : "waiting for IO to complete during shutdown, %u in-flight IOs",
1309 : dclist_count(&pgaio_my_backend->in_flight_ios));
1310 :
1311 : /* see comment in pgaio_io_wait_for_free() about raciness */
1312 18 : pgaio_io_wait(ioh, generation);
1313 : }
1314 :
1315 39002 : pgaio_my_backend = NULL;
1316 39002 : }
1317 :
1318 : void
1319 2216 : assign_io_method(int newval, void *extra)
1320 : {
1321 : Assert(pgaio_method_ops_table[newval] != NULL);
1322 : Assert(newval < lengthof(io_method_options));
1323 :
1324 2216 : pgaio_method_ops = pgaio_method_ops_table[newval];
1325 2216 : }
1326 :
1327 : bool
1328 4316 : check_io_max_concurrency(int *newval, void **extra, GucSource source)
1329 : {
1330 4316 : if (*newval == -1)
1331 : {
1332 : /*
1333 : * Auto-tuning will be applied later during startup, as auto-tuning
1334 : * depends on the value of various GUCs.
1335 : */
1336 2194 : return true;
1337 : }
1338 2122 : else if (*newval == 0)
1339 : {
1340 0 : GUC_check_errdetail("Only -1 or values bigger than 0 are valid.");
1341 0 : return false;
1342 : }
1343 :
1344 2122 : return true;
1345 : }
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