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backend_status.c
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1/* ----------
2 * backend_status.c
3 * Backend status reporting infrastructure.
4 *
5 * Copyright (c) 2001-2025, PostgreSQL Global Development Group
6 *
7 *
8 * IDENTIFICATION
9 * src/backend/utils/activity/backend_status.c
10 * ----------
11 */
12#include "postgres.h"
13
14#include "access/xact.h"
15#include "libpq/libpq-be.h"
16#include "miscadmin.h"
17#include "pg_trace.h"
18#include "pgstat.h"
19#include "storage/ipc.h"
20#include "storage/proc.h" /* for MyProc */
21#include "storage/procarray.h"
22#include "utils/ascii.h"
23#include "utils/guc.h" /* for application_name */
24#include "utils/memutils.h"
25
26
27/* ----------
28 * Total number of backends including auxiliary
29 *
30 * We reserve a slot for each possible PGPROC entry, including aux processes.
31 * (But not including PGPROC entries reserved for prepared xacts; they are not
32 * real processes.)
33 * ----------
34 */
35#define NumBackendStatSlots (MaxBackends + NUM_AUXILIARY_PROCS)
36
37
38/* ----------
39 * GUC parameters
40 * ----------
41 */
44
45
46/* exposed so that backend_progress.c can access it */
48
49
51static char *BackendAppnameBuffer = NULL;
52static char *BackendClientHostnameBuffer = NULL;
53static char *BackendActivityBuffer = NULL;
55#ifdef USE_SSL
56static PgBackendSSLStatus *BackendSslStatusBuffer = NULL;
57#endif
58#ifdef ENABLE_GSS
59static PgBackendGSSStatus *BackendGssStatusBuffer = NULL;
60#endif
61
62
63/* Status for backends including auxiliary */
65
66/* Total number of backends including auxiliary */
67static int localNumBackends = 0;
68
70
71
72static void pgstat_beshutdown_hook(int code, Datum arg);
73static void pgstat_read_current_status(void);
75
76
77/*
78 * Report shared-memory space needed by BackendStatusShmemInit.
79 */
80Size
82{
83 Size size;
84
85 /* BackendStatusArray: */
87 /* BackendAppnameBuffer: */
88 size = add_size(size,
90 /* BackendClientHostnameBuffer: */
91 size = add_size(size,
93 /* BackendActivityBuffer: */
94 size = add_size(size,
96#ifdef USE_SSL
97 /* BackendSslStatusBuffer: */
98 size = add_size(size,
100#endif
101#ifdef ENABLE_GSS
102 /* BackendGssStatusBuffer: */
103 size = add_size(size,
105#endif
106 return size;
107}
108
109/*
110 * Initialize the shared status array and several string buffers
111 * during postmaster startup.
112 */
113void
115{
116 Size size;
117 bool found;
118 int i;
119 char *buffer;
120
121 /* Create or attach to the shared array */
124 ShmemInitStruct("Backend Status Array", size, &found);
125
126 if (!found)
127 {
128 /*
129 * We're the first - initialize.
130 */
131 MemSet(BackendStatusArray, 0, size);
132 }
133
134 /* Create or attach to the shared appname buffer */
136 BackendAppnameBuffer = (char *)
137 ShmemInitStruct("Backend Application Name Buffer", size, &found);
138
139 if (!found)
140 {
142
143 /* Initialize st_appname pointers. */
144 buffer = BackendAppnameBuffer;
145 for (i = 0; i < NumBackendStatSlots; i++)
146 {
148 buffer += NAMEDATALEN;
149 }
150 }
151
152 /* Create or attach to the shared client hostname buffer */
155 ShmemInitStruct("Backend Client Host Name Buffer", size, &found);
156
157 if (!found)
158 {
160
161 /* Initialize st_clienthostname pointers. */
163 for (i = 0; i < NumBackendStatSlots; i++)
164 {
166 buffer += NAMEDATALEN;
167 }
168 }
169
170 /* Create or attach to the shared activity buffer */
173 BackendActivityBuffer = (char *)
174 ShmemInitStruct("Backend Activity Buffer",
176 &found);
177
178 if (!found)
179 {
181
182 /* Initialize st_activity pointers. */
183 buffer = BackendActivityBuffer;
184 for (i = 0; i < NumBackendStatSlots; i++)
185 {
188 }
189 }
190
191#ifdef USE_SSL
192 /* Create or attach to the shared SSL status buffer */
194 BackendSslStatusBuffer = (PgBackendSSLStatus *)
195 ShmemInitStruct("Backend SSL Status Buffer", size, &found);
196
197 if (!found)
198 {
200
201 MemSet(BackendSslStatusBuffer, 0, size);
202
203 /* Initialize st_sslstatus pointers. */
204 ptr = BackendSslStatusBuffer;
205 for (i = 0; i < NumBackendStatSlots; i++)
206 {
208 ptr++;
209 }
210 }
211#endif
212
213#ifdef ENABLE_GSS
214 /* Create or attach to the shared GSSAPI status buffer */
216 BackendGssStatusBuffer = (PgBackendGSSStatus *)
217 ShmemInitStruct("Backend GSS Status Buffer", size, &found);
218
219 if (!found)
220 {
222
223 MemSet(BackendGssStatusBuffer, 0, size);
224
225 /* Initialize st_gssstatus pointers. */
226 ptr = BackendGssStatusBuffer;
227 for (i = 0; i < NumBackendStatSlots; i++)
228 {
230 ptr++;
231 }
232 }
233#endif
234}
235
236/*
237 * Initialize pgstats backend activity state, and set up our on-proc-exit
238 * hook. Called from InitPostgres and AuxiliaryProcessMain. MyProcNumber must
239 * be set, but we must not have started any transaction yet (since the exit
240 * hook must run after the last transaction exit).
241 *
242 * NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
243 */
244void
246{
247 /* Initialize MyBEEntry */
251
252 /* Set up a process-exit hook to clean up */
254}
255
256
257/* ----------
258 * pgstat_bestart_initial() -
259 *
260 * Initialize this backend's entry in the PgBackendStatus array. Called
261 * from InitPostgres and AuxiliaryProcessMain.
262 *
263 * Clears out a new pgstat entry, initializing it to suitable defaults and
264 * reporting STATE_STARTING. Backends should continue filling in any
265 * transport security details as needed with pgstat_bestart_security(), and
266 * must finally exit STATE_STARTING by calling pgstat_bestart_final().
267 * ----------
268 */
269void
271{
272 volatile PgBackendStatus *vbeentry = MyBEEntry;
273 PgBackendStatus lbeentry;
274
275 /* pgstats state must be initialized from pgstat_beinit() */
276 Assert(vbeentry != NULL);
277
278 /*
279 * To minimize the time spent modifying the PgBackendStatus entry, and
280 * avoid risk of errors inside the critical section, we first copy the
281 * shared-memory struct to a local variable, then modify the data in the
282 * local variable, then copy the local variable back to shared memory.
283 * Only the last step has to be inside the critical section.
284 *
285 * Most of the data we copy from shared memory is just going to be
286 * overwritten, but the struct's not so large that it's worth the
287 * maintenance hassle to copy only the needful fields.
288 */
289 memcpy(&lbeentry,
290 unvolatize(PgBackendStatus *, vbeentry),
291 sizeof(PgBackendStatus));
292
293 /*
294 * Now fill in all the fields of lbeentry, except for strings that are
295 * out-of-line data. Those have to be handled separately, below.
296 */
297 lbeentry.st_procpid = MyProcPid;
298 lbeentry.st_backendType = MyBackendType;
300 lbeentry.st_activity_start_timestamp = 0;
301 lbeentry.st_state_start_timestamp = 0;
302 lbeentry.st_xact_start_timestamp = 0;
303 lbeentry.st_databaseid = InvalidOid;
304 lbeentry.st_userid = InvalidOid;
305
306 /*
307 * We may not have a MyProcPort (eg, if this is the autovacuum process).
308 * If so, use all-zeroes client address, which is dealt with specially in
309 * pg_stat_get_backend_client_addr and pg_stat_get_backend_client_port.
310 */
311 if (MyProcPort)
312 memcpy(&lbeentry.st_clientaddr, &MyProcPort->raddr,
313 sizeof(lbeentry.st_clientaddr));
314 else
315 MemSet(&lbeentry.st_clientaddr, 0, sizeof(lbeentry.st_clientaddr));
316
317 lbeentry.st_ssl = false;
318 lbeentry.st_gss = false;
319
320 lbeentry.st_state = STATE_STARTING;
323 lbeentry.st_query_id = UINT64CONST(0);
324 lbeentry.st_plan_id = UINT64CONST(0);
325
326 /*
327 * we don't zero st_progress_param here to save cycles; nobody should
328 * examine it until st_progress_command has been set to something other
329 * than PROGRESS_COMMAND_INVALID
330 */
331
332 /*
333 * We're ready to enter the critical section that fills the shared-memory
334 * status entry. We follow the protocol of bumping st_changecount before
335 * and after; and make sure it's even afterwards. We use a volatile
336 * pointer here to ensure the compiler doesn't try to get cute.
337 */
339
340 /* make sure we'll memcpy the same st_changecount back */
341 lbeentry.st_changecount = vbeentry->st_changecount;
342
343 memcpy(unvolatize(PgBackendStatus *, vbeentry),
344 &lbeentry,
345 sizeof(PgBackendStatus));
346
347 /*
348 * We can write the out-of-line strings and structs using the pointers
349 * that are in lbeentry; this saves some de-volatilizing messiness.
350 */
351 lbeentry.st_appname[0] = '\0';
355 else
356 lbeentry.st_clienthostname[0] = '\0';
357 lbeentry.st_activity_raw[0] = '\0';
358 /* Also make sure the last byte in each string area is always 0 */
359 lbeentry.st_appname[NAMEDATALEN - 1] = '\0';
360 lbeentry.st_clienthostname[NAMEDATALEN - 1] = '\0';
362
363 /* These structs can just start from zeroes each time */
364#ifdef USE_SSL
365 memset(lbeentry.st_sslstatus, 0, sizeof(PgBackendSSLStatus));
366#endif
367#ifdef ENABLE_GSS
368 memset(lbeentry.st_gssstatus, 0, sizeof(PgBackendGSSStatus));
369#endif
370
372}
373
374/* ----------
375 * pgstat_bestart_security() -
376 *
377 * Fill in SSL and GSS information for the pgstat entry. This is the second
378 * optional step taken when filling a backend's entry, not required for
379 * auxiliary processes.
380 *
381 * This should only be called from backends with a MyProcPort.
382 * ----------
383 */
384void
386{
387 volatile PgBackendStatus *beentry = MyBEEntry;
388 bool ssl = false;
389 bool gss = false;
390#ifdef USE_SSL
391 PgBackendSSLStatus lsslstatus;
392 PgBackendSSLStatus *st_sslstatus;
393#endif
394#ifdef ENABLE_GSS
395 PgBackendGSSStatus lgssstatus;
396 PgBackendGSSStatus *st_gssstatus;
397#endif
398
399 /* pgstats state must be initialized from pgstat_beinit() */
400 Assert(beentry != NULL);
401 Assert(MyProcPort); /* otherwise there's no point */
402
403#ifdef USE_SSL
404 st_sslstatus = beentry->st_sslstatus;
405 memset(&lsslstatus, 0, sizeof(lsslstatus));
406
408 {
409 ssl = true;
416 }
417#endif
418
419#ifdef ENABLE_GSS
420 st_gssstatus = beentry->st_gssstatus;
421 memset(&lgssstatus, 0, sizeof(lgssstatus));
422
423 if (MyProcPort->gss != NULL)
424 {
425 const char *princ = be_gssapi_get_princ(MyProcPort);
426
427 gss = true;
431 if (princ)
432 strlcpy(lgssstatus.gss_princ, princ, NAMEDATALEN);
433 }
434#endif
435
436 /*
437 * Update my status entry, following the protocol of bumping
438 * st_changecount before and after. We use a volatile pointer here to
439 * ensure the compiler doesn't try to get cute.
440 */
442
443 beentry->st_ssl = ssl;
444 beentry->st_gss = gss;
445
446#ifdef USE_SSL
447 memcpy(st_sslstatus, &lsslstatus, sizeof(PgBackendSSLStatus));
448#endif
449#ifdef ENABLE_GSS
450 memcpy(st_gssstatus, &lgssstatus, sizeof(PgBackendGSSStatus));
451#endif
452
454}
455
456/* ----------
457 * pgstat_bestart_final() -
458 *
459 * Finalizes the state of this backend's entry by filling in the user and
460 * database IDs, clearing STATE_STARTING, and reporting the application_name.
461 *
462 * We must be inside a transaction if this is not an auxiliary process, as
463 * we may need to do encoding conversion.
464 * ----------
465 */
466void
468{
469 volatile PgBackendStatus *beentry = MyBEEntry;
470 Oid userid;
471
472 /* pgstats state must be initialized from pgstat_beinit() */
473 Assert(beentry != NULL);
474
475 /* We have userid for client-backends, wal-sender and bgworker processes */
479 userid = GetSessionUserId();
480 else
481 userid = InvalidOid;
482
483 /*
484 * Update my status entry, following the protocol of bumping
485 * st_changecount before and after. We use a volatile pointer here to
486 * ensure the compiler doesn't try to get cute.
487 */
489
490 beentry->st_databaseid = MyDatabaseId;
491 beentry->st_userid = userid;
492 beentry->st_state = STATE_UNDEFINED;
493
495
496 /* Create the backend statistics entry */
499
500 /* Update app name to current GUC setting */
503}
504
505/*
506 * Clear out our entry in the PgBackendStatus array.
507 */
508static void
510{
511 volatile PgBackendStatus *beentry = MyBEEntry;
512
513 /*
514 * Clear my status entry, following the protocol of bumping st_changecount
515 * before and after. We use a volatile pointer here to ensure the
516 * compiler doesn't try to get cute.
517 */
519
520 beentry->st_procpid = 0; /* mark invalid */
521
523
524 /* so that functions can check if backend_status.c is up via MyBEEntry */
525 MyBEEntry = NULL;
526}
527
528/*
529 * Discard any data collected in the current transaction. Any subsequent
530 * request will cause new snapshots to be read.
531 *
532 * This is also invoked during transaction commit or abort to discard the
533 * no-longer-wanted snapshot.
534 */
535void
537{
538 /* Release memory, if any was allocated */
540 {
543 }
544
545 /* Reset variables */
548}
549
550static void
552{
555 "Backend Status Snapshot",
557}
558
559
560/* ----------
561 * pgstat_report_activity() -
562 *
563 * Called from tcop/postgres.c to report what the backend is actually doing
564 * (but note cmd_str can be NULL for certain cases).
565 *
566 * All updates of the status entry follow the protocol of bumping
567 * st_changecount before and after. We use a volatile pointer here to
568 * ensure the compiler doesn't try to get cute.
569 * ----------
570 */
571void
573{
574 volatile PgBackendStatus *beentry = MyBEEntry;
575 TimestampTz start_timestamp;
576 TimestampTz current_timestamp;
577 int len = 0;
578
579 TRACE_POSTGRESQL_STATEMENT_STATUS(cmd_str);
580
581 if (!beentry)
582 return;
583
585 {
586 if (beentry->st_state != STATE_DISABLED)
587 {
588 volatile PGPROC *proc = MyProc;
589
590 /*
591 * track_activities is disabled, but we last reported a
592 * non-disabled state. As our final update, change the state and
593 * clear fields we will not be updating anymore.
594 */
596 beentry->st_state = STATE_DISABLED;
597 beentry->st_state_start_timestamp = 0;
598 beentry->st_activity_raw[0] = '\0';
599 beentry->st_activity_start_timestamp = 0;
600 /* st_xact_start_timestamp and wait_event_info are also disabled */
601 beentry->st_xact_start_timestamp = 0;
602 beentry->st_query_id = UINT64CONST(0);
603 beentry->st_plan_id = UINT64CONST(0);
604 proc->wait_event_info = 0;
606 }
607 return;
608 }
609
610 /*
611 * To minimize the time spent modifying the entry, and avoid risk of
612 * errors inside the critical section, fetch all the needed data first.
613 */
614 start_timestamp = GetCurrentStatementStartTimestamp();
615 if (cmd_str != NULL)
616 {
617 /*
618 * Compute length of to-be-stored string unaware of multi-byte
619 * characters. For speed reasons that'll get corrected on read, rather
620 * than computed every write.
621 */
622 len = Min(strlen(cmd_str), pgstat_track_activity_query_size - 1);
623 }
624 current_timestamp = GetCurrentTimestamp();
625
626 /*
627 * If the state has changed from "active" or "idle in transaction",
628 * calculate the duration.
629 */
630 if ((beentry->st_state == STATE_RUNNING ||
631 beentry->st_state == STATE_FASTPATH ||
632 beentry->st_state == STATE_IDLEINTRANSACTION ||
634 state != beentry->st_state)
635 {
636 long secs;
637 int usecs;
638
640 current_timestamp,
641 &secs, &usecs);
642
643 if (beentry->st_state == STATE_RUNNING ||
644 beentry->st_state == STATE_FASTPATH)
645 pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);
646 else
647 pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 + usecs);
648 }
649
650 /*
651 * Now update the status entry
652 */
654
655 beentry->st_state = state;
656 beentry->st_state_start_timestamp = current_timestamp;
657
658 /*
659 * If a new query is started, we reset the query identifier as it'll only
660 * be known after parse analysis, to avoid reporting last query's
661 * identifier.
662 */
663 if (state == STATE_RUNNING)
664 {
665 beentry->st_query_id = UINT64CONST(0);
666 beentry->st_plan_id = UINT64CONST(0);
667 }
668
669 if (cmd_str != NULL)
670 {
671 memcpy(beentry->st_activity_raw, cmd_str, len);
672 beentry->st_activity_raw[len] = '\0';
673 beentry->st_activity_start_timestamp = start_timestamp;
674 }
675
677}
678
679/* --------
680 * pgstat_report_query_id() -
681 *
682 * Called to update top-level query identifier.
683 * --------
684 */
685void
686pgstat_report_query_id(uint64 query_id, bool force)
687{
688 volatile PgBackendStatus *beentry = MyBEEntry;
689
690 /*
691 * if track_activities is disabled, st_query_id should already have been
692 * reset
693 */
694 if (!beentry || !pgstat_track_activities)
695 return;
696
697 /*
698 * We only report the top-level query identifiers. The stored query_id is
699 * reset when a backend calls pgstat_report_activity(STATE_RUNNING), or
700 * with an explicit call to this function using the force flag. If the
701 * saved query identifier is not zero it means that it's not a top-level
702 * command, so ignore the one provided unless it's an explicit call to
703 * reset the identifier.
704 */
705 if (beentry->st_query_id != 0 && !force)
706 return;
707
708 /*
709 * Update my status entry, following the protocol of bumping
710 * st_changecount before and after. We use a volatile pointer here to
711 * ensure the compiler doesn't try to get cute.
712 */
714 beentry->st_query_id = query_id;
716}
717
718/* --------
719 * pgstat_report_plan_id() -
720 *
721 * Called to update top-level plan identifier.
722 * --------
723 */
724void
725pgstat_report_plan_id(uint64 plan_id, bool force)
726{
727 volatile PgBackendStatus *beentry = MyBEEntry;
728
729 /*
730 * if track_activities is disabled, st_plan_id should already have been
731 * reset
732 */
733 if (!beentry || !pgstat_track_activities)
734 return;
735
736 /*
737 * We only report the top-level plan identifiers. The stored plan_id is
738 * reset when a backend calls pgstat_report_activity(STATE_RUNNING), or
739 * with an explicit call to this function using the force flag. If the
740 * saved plan identifier is not zero it means that it's not a top-level
741 * command, so ignore the one provided unless it's an explicit call to
742 * reset the identifier.
743 */
744 if (beentry->st_plan_id != 0 && !force)
745 return;
746
747 /*
748 * Update my status entry, following the protocol of bumping
749 * st_changecount before and after. We use a volatile pointer here to
750 * ensure the compiler doesn't try to get cute.
751 */
753 beentry->st_plan_id = plan_id;
755}
756
757/* ----------
758 * pgstat_report_appname() -
759 *
760 * Called to update our application name.
761 * ----------
762 */
763void
764pgstat_report_appname(const char *appname)
765{
766 volatile PgBackendStatus *beentry = MyBEEntry;
767 int len;
768
769 if (!beentry)
770 return;
771
772 /* This should be unnecessary if GUC did its job, but be safe */
773 len = pg_mbcliplen(appname, strlen(appname), NAMEDATALEN - 1);
774
775 /*
776 * Update my status entry, following the protocol of bumping
777 * st_changecount before and after. We use a volatile pointer here to
778 * ensure the compiler doesn't try to get cute.
779 */
781
782 memcpy(beentry->st_appname, appname, len);
783 beentry->st_appname[len] = '\0';
784
786}
787
788/*
789 * Report current transaction start timestamp as the specified value.
790 * Zero means there is no active transaction.
791 */
792void
794{
795 volatile PgBackendStatus *beentry = MyBEEntry;
796
797 if (!pgstat_track_activities || !beentry)
798 return;
799
800 /*
801 * Update my status entry, following the protocol of bumping
802 * st_changecount before and after. We use a volatile pointer here to
803 * ensure the compiler doesn't try to get cute.
804 */
806
807 beentry->st_xact_start_timestamp = tstamp;
808
810}
811
812/* ----------
813 * pgstat_read_current_status() -
814 *
815 * Copy the current contents of the PgBackendStatus array to local memory,
816 * if not already done in this transaction.
817 * ----------
818 */
819static void
821{
822 volatile PgBackendStatus *beentry;
823 LocalPgBackendStatus *localtable;
824 LocalPgBackendStatus *localentry;
825 char *localappname,
826 *localclienthostname,
827 *localactivity;
828#ifdef USE_SSL
829 PgBackendSSLStatus *localsslstatus;
830#endif
831#ifdef ENABLE_GSS
832 PgBackendGSSStatus *localgssstatus;
833#endif
834 ProcNumber procNumber;
835
837 return; /* already done */
838
840
841 /*
842 * Allocate storage for local copy of state data. We can presume that
843 * none of these requests overflow size_t, because we already calculated
844 * the same values using mul_size during shmem setup. However, with
845 * probably-silly values of pgstat_track_activity_query_size and
846 * max_connections, the localactivity buffer could exceed 1GB, so use
847 * "huge" allocation for that one.
848 */
849 localtable = (LocalPgBackendStatus *)
852 localappname = (char *)
855 localclienthostname = (char *)
858 localactivity = (char *)
862#ifdef USE_SSL
863 localsslstatus = (PgBackendSSLStatus *)
866#endif
867#ifdef ENABLE_GSS
868 localgssstatus = (PgBackendGSSStatus *)
871#endif
872
874
875 beentry = BackendStatusArray;
876 localentry = localtable;
877 for (procNumber = 0; procNumber < NumBackendStatSlots; procNumber++)
878 {
879 /*
880 * Follow the protocol of retrying if st_changecount changes while we
881 * copy the entry, or if it's odd. (The check for odd is needed to
882 * cover the case where we are able to completely copy the entry while
883 * the source backend is between increment steps.) We use a volatile
884 * pointer here to ensure the compiler doesn't try to get cute.
885 */
886 for (;;)
887 {
888 int before_changecount;
889 int after_changecount;
890
891 pgstat_begin_read_activity(beentry, before_changecount);
892
893 localentry->backendStatus.st_procpid = beentry->st_procpid;
894 /* Skip all the data-copying work if entry is not in use */
895 if (localentry->backendStatus.st_procpid > 0)
896 {
897 memcpy(&localentry->backendStatus, unvolatize(PgBackendStatus *, beentry), sizeof(PgBackendStatus));
898
899 /*
900 * For each PgBackendStatus field that is a pointer, copy the
901 * pointed-to data, then adjust the local copy of the pointer
902 * field to point at the local copy of the data.
903 *
904 * strcpy is safe even if the string is modified concurrently,
905 * because there's always a \0 at the end of the buffer.
906 */
907 strcpy(localappname, beentry->st_appname);
908 localentry->backendStatus.st_appname = localappname;
909 strcpy(localclienthostname, beentry->st_clienthostname);
910 localentry->backendStatus.st_clienthostname = localclienthostname;
911 strcpy(localactivity, beentry->st_activity_raw);
912 localentry->backendStatus.st_activity_raw = localactivity;
913#ifdef USE_SSL
914 if (beentry->st_ssl)
915 {
916 memcpy(localsslstatus, beentry->st_sslstatus, sizeof(PgBackendSSLStatus));
917 localentry->backendStatus.st_sslstatus = localsslstatus;
918 }
919#endif
920#ifdef ENABLE_GSS
921 if (beentry->st_gss)
922 {
923 memcpy(localgssstatus, beentry->st_gssstatus, sizeof(PgBackendGSSStatus));
924 localentry->backendStatus.st_gssstatus = localgssstatus;
925 }
926#endif
927 }
928
929 pgstat_end_read_activity(beentry, after_changecount);
930
931 if (pgstat_read_activity_complete(before_changecount,
932 after_changecount))
933 break;
934
935 /* Make sure we can break out of loop if stuck... */
937 }
938
939 /* Only valid entries get included into the local array */
940 if (localentry->backendStatus.st_procpid > 0)
941 {
942 /*
943 * The BackendStatusArray index is exactly the ProcNumber of the
944 * source backend. Note that this means localBackendStatusTable
945 * is in order by proc_number. pgstat_get_beentry_by_proc_number()
946 * depends on that.
947 */
948 localentry->proc_number = procNumber;
950 &localentry->backend_xid,
951 &localentry->backend_xmin,
952 &localentry->backend_subxact_count,
953 &localentry->backend_subxact_overflowed);
954
955 localentry++;
956 localappname += NAMEDATALEN;
957 localclienthostname += NAMEDATALEN;
958 localactivity += pgstat_track_activity_query_size;
959#ifdef USE_SSL
960 localsslstatus++;
961#endif
962#ifdef ENABLE_GSS
963 localgssstatus++;
964#endif
966 }
967
968 beentry++;
969 }
970
971 /* Set the pointer only after completion of a valid table */
972 localBackendStatusTable = localtable;
973}
974
975
976/* ----------
977 * pgstat_get_backend_current_activity() -
978 *
979 * Return a string representing the current activity of the backend with
980 * the specified PID. This looks directly at the BackendStatusArray,
981 * and so will provide current information regardless of the age of our
982 * transaction's snapshot of the status array.
983 *
984 * It is the caller's responsibility to invoke this only for backends whose
985 * state is expected to remain stable while the result is in use. The
986 * only current use is in deadlock reporting, where we can expect that
987 * the target backend is blocked on a lock. (There are corner cases
988 * where the target's wait could get aborted while we are looking at it,
989 * but the very worst consequence is to return a pointer to a string
990 * that's been changed, so we won't worry too much.)
991 *
992 * Note: return strings for special cases match pg_stat_get_backend_activity.
993 * ----------
994 */
995const char *
997{
998 PgBackendStatus *beentry;
999 int i;
1000
1001 beentry = BackendStatusArray;
1002 for (i = 1; i <= MaxBackends; i++)
1003 {
1004 /*
1005 * Although we expect the target backend's entry to be stable, that
1006 * doesn't imply that anyone else's is. To avoid identifying the
1007 * wrong backend, while we check for a match to the desired PID we
1008 * must follow the protocol of retrying if st_changecount changes
1009 * while we examine the entry, or if it's odd. (This might be
1010 * unnecessary, since fetching or storing an int is almost certainly
1011 * atomic, but let's play it safe.) We use a volatile pointer here to
1012 * ensure the compiler doesn't try to get cute.
1013 */
1014 volatile PgBackendStatus *vbeentry = beentry;
1015 bool found;
1016
1017 for (;;)
1018 {
1019 int before_changecount;
1020 int after_changecount;
1021
1022 pgstat_begin_read_activity(vbeentry, before_changecount);
1023
1024 found = (vbeentry->st_procpid == pid);
1025
1026 pgstat_end_read_activity(vbeentry, after_changecount);
1027
1028 if (pgstat_read_activity_complete(before_changecount,
1029 after_changecount))
1030 break;
1031
1032 /* Make sure we can break out of loop if stuck... */
1034 }
1035
1036 if (found)
1037 {
1038 /* Now it is safe to use the non-volatile pointer */
1039 if (checkUser && !superuser() && beentry->st_userid != GetUserId())
1040 return "<insufficient privilege>";
1041 else if (*(beentry->st_activity_raw) == '\0')
1042 return "<command string not enabled>";
1043 else
1044 {
1045 /* this'll leak a bit of memory, but that seems acceptable */
1046 return pgstat_clip_activity(beentry->st_activity_raw);
1047 }
1048 }
1049
1050 beentry++;
1051 }
1052
1053 /* If we get here, caller is in error ... */
1054 return "<backend information not available>";
1055}
1056
1057/* ----------
1058 * pgstat_get_crashed_backend_activity() -
1059 *
1060 * Return a string representing the current activity of the backend with
1061 * the specified PID. Like the function above, but reads shared memory with
1062 * the expectation that it may be corrupt. On success, copy the string
1063 * into the "buffer" argument and return that pointer. On failure,
1064 * return NULL.
1065 *
1066 * This function is only intended to be used by the postmaster to report the
1067 * query that crashed a backend. In particular, no attempt is made to
1068 * follow the correct concurrency protocol when accessing the
1069 * BackendStatusArray. But that's OK, in the worst case we'll return a
1070 * corrupted message. We also must take care not to trip on ereport(ERROR).
1071 * ----------
1072 */
1073const char *
1074pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
1075{
1076 volatile PgBackendStatus *beentry;
1077 int i;
1078
1079 beentry = BackendStatusArray;
1080
1081 /*
1082 * We probably shouldn't get here before shared memory has been set up,
1083 * but be safe.
1084 */
1085 if (beentry == NULL || BackendActivityBuffer == NULL)
1086 return NULL;
1087
1088 for (i = 1; i <= MaxBackends; i++)
1089 {
1090 if (beentry->st_procpid == pid)
1091 {
1092 /* Read pointer just once, so it can't change after validation */
1093 const char *activity = beentry->st_activity_raw;
1094 const char *activity_last;
1095
1096 /*
1097 * We mustn't access activity string before we verify that it
1098 * falls within the BackendActivityBuffer. To make sure that the
1099 * entire string including its ending is contained within the
1100 * buffer, subtract one activity length from the buffer size.
1101 */
1104
1105 if (activity < BackendActivityBuffer ||
1106 activity > activity_last)
1107 return NULL;
1108
1109 /* If no string available, no point in a report */
1110 if (activity[0] == '\0')
1111 return NULL;
1112
1113 /*
1114 * Copy only ASCII-safe characters so we don't run into encoding
1115 * problems when reporting the message; and be sure not to run off
1116 * the end of memory. As only ASCII characters are reported, it
1117 * doesn't seem necessary to perform multibyte aware clipping.
1118 */
1119 ascii_safe_strlcpy(buffer, activity,
1121
1122 return buffer;
1123 }
1124
1125 beentry++;
1126 }
1127
1128 /* PID not found */
1129 return NULL;
1130}
1131
1132/* ----------
1133 * pgstat_get_my_query_id() -
1134 *
1135 * Return current backend's query identifier.
1136 */
1137uint64
1139{
1140 if (!MyBEEntry)
1141 return 0;
1142
1143 /*
1144 * There's no need for a lock around pgstat_begin_read_activity /
1145 * pgstat_end_read_activity here as it's only called from
1146 * pg_stat_get_activity which is already protected, or from the same
1147 * backend which means that there won't be concurrent writes.
1148 */
1149 return MyBEEntry->st_query_id;
1150}
1151
1152/* ----------
1153 * pgstat_get_my_plan_id() -
1154 *
1155 * Return current backend's plan identifier.
1156 */
1157uint64
1159{
1160 if (!MyBEEntry)
1161 return 0;
1162
1163 /* No need for a lock, for roughly the same reasons as above. */
1164 return MyBEEntry->st_plan_id;
1165}
1166
1167/* ----------
1168 * pgstat_get_backend_type_by_proc_number() -
1169 *
1170 * Return the type of the backend with the specified ProcNumber. This looks
1171 * directly at the BackendStatusArray, so the return value may be out of date.
1172 * The only current use of this function is in pg_signal_backend(), which is
1173 * inherently racy, so we don't worry too much about this.
1174 *
1175 * It is the caller's responsibility to use this wisely; at minimum, callers
1176 * should ensure that procNumber is valid and perform the required permissions
1177 * checks.
1178 * ----------
1179 */
1182{
1183 volatile PgBackendStatus *status = &BackendStatusArray[procNumber];
1184
1185 /*
1186 * We bypass the changecount mechanism since fetching and storing an int
1187 * is almost certainly atomic.
1188 */
1189 return status->st_backendType;
1190}
1191
1192/* ----------
1193 * cmp_lbestatus
1194 *
1195 * Comparison function for bsearch() on an array of LocalPgBackendStatus.
1196 * The proc_number field is used to compare the arguments.
1197 * ----------
1198 */
1199static int
1200cmp_lbestatus(const void *a, const void *b)
1201{
1202 const LocalPgBackendStatus *lbestatus1 = (const LocalPgBackendStatus *) a;
1203 const LocalPgBackendStatus *lbestatus2 = (const LocalPgBackendStatus *) b;
1204
1205 return lbestatus1->proc_number - lbestatus2->proc_number;
1206}
1207
1208/* ----------
1209 * pgstat_get_beentry_by_proc_number() -
1210 *
1211 * Support function for the SQL-callable pgstat* functions. Returns
1212 * our local copy of the current-activity entry for one backend,
1213 * or NULL if the given beid doesn't identify any known session.
1214 *
1215 * The argument is the ProcNumber of the desired session
1216 * (note that this is unlike pgstat_get_local_beentry_by_index()).
1217 *
1218 * NB: caller is responsible for a check if the user is permitted to see
1219 * this info (especially the querystring).
1220 * ----------
1221 */
1224{
1226
1227 if (ret)
1228 return &ret->backendStatus;
1229
1230 return NULL;
1231}
1232
1233
1234/* ----------
1235 * pgstat_get_local_beentry_by_proc_number() -
1236 *
1237 * Like pgstat_get_beentry_by_proc_number() but with locally computed additions
1238 * (like xid and xmin values of the backend)
1239 *
1240 * The argument is the ProcNumber of the desired session
1241 * (note that this is unlike pgstat_get_local_beentry_by_index()).
1242 *
1243 * NB: caller is responsible for checking if the user is permitted to see this
1244 * info (especially the querystring).
1245 * ----------
1246 */
1249{
1251
1253
1254 /*
1255 * Since the localBackendStatusTable is in order by proc_number, we can
1256 * use bsearch() to search it efficiently.
1257 */
1258 key.proc_number = procNumber;
1261}
1262
1263
1264/* ----------
1265 * pgstat_get_local_beentry_by_index() -
1266 *
1267 * Like pgstat_get_beentry_by_proc_number() but with locally computed
1268 * additions (like xid and xmin values of the backend)
1269 *
1270 * The idx argument is a 1-based index in the localBackendStatusTable
1271 * (note that this is unlike pgstat_get_beentry_by_proc_number()).
1272 * Returns NULL if the argument is out of range (no current caller does that).
1273 *
1274 * NB: caller is responsible for a check if the user is permitted to see
1275 * this info (especially the querystring).
1276 * ----------
1277 */
1280{
1282
1283 if (idx < 1 || idx > localNumBackends)
1284 return NULL;
1285
1286 return &localBackendStatusTable[idx - 1];
1287}
1288
1289
1290/* ----------
1291 * pgstat_fetch_stat_numbackends() -
1292 *
1293 * Support function for the SQL-callable pgstat* functions. Returns
1294 * the number of sessions known in the localBackendStatusTable, i.e.
1295 * the maximum 1-based index to pass to pgstat_get_local_beentry_by_index().
1296 * ----------
1297 */
1298int
1300{
1302
1303 return localNumBackends;
1304}
1305
1306/*
1307 * Convert a potentially unsafely truncated activity string (see
1308 * PgBackendStatus.st_activity_raw's documentation) into a correctly truncated
1309 * one.
1310 *
1311 * The returned string is allocated in the caller's memory context and may be
1312 * freed.
1313 */
1314char *
1315pgstat_clip_activity(const char *raw_activity)
1316{
1317 char *activity;
1318 int rawlen;
1319 int cliplen;
1320
1321 /*
1322 * Some callers, like pgstat_get_backend_current_activity(), do not
1323 * guarantee that the buffer isn't concurrently modified. We try to take
1324 * care that the buffer is always terminated by a NUL byte regardless, but
1325 * let's still be paranoid about the string's length. In those cases the
1326 * underlying buffer is guaranteed to be pgstat_track_activity_query_size
1327 * large.
1328 */
1329 activity = pnstrdup(raw_activity, pgstat_track_activity_query_size - 1);
1330
1331 /* now double-guaranteed to be NUL terminated */
1332 rawlen = strlen(activity);
1333
1334 /*
1335 * All supported server-encodings make it possible to determine the length
1336 * of a multi-byte character from its first byte (this is not the case for
1337 * client encodings, see GB18030). As st_activity is always stored using
1338 * server encoding, this allows us to perform multi-byte aware truncation,
1339 * even if the string earlier was truncated in the middle of a multi-byte
1340 * character.
1341 */
1342 cliplen = pg_mbcliplen(activity, rawlen,
1344
1345 activity[cliplen] = '\0';
1346
1347 return activity;
1348}
Datum idx(PG_FUNCTION_ARGS)
Definition: _int_op.c:262
void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz)
Definition: ascii.c:174
void TimestampDifference(TimestampTz start_time, TimestampTz stop_time, long *secs, int *microsecs)
Definition: timestamp.c:1721
TimestampTz GetCurrentTimestamp(void)
Definition: timestamp.c:1645
@ PROGRESS_COMMAND_INVALID
#define NumBackendStatSlots
int pgstat_fetch_stat_numbackends(void)
PgBackendStatus * MyBEEntry
uint64 pgstat_get_my_query_id(void)
LocalPgBackendStatus * pgstat_get_local_beentry_by_proc_number(ProcNumber procNumber)
void pgstat_clear_backend_activity_snapshot(void)
static LocalPgBackendStatus * localBackendStatusTable
void pgstat_bestart_security(void)
static int localNumBackends
void pgstat_bestart_initial(void)
static void pgstat_beshutdown_hook(int code, Datum arg)
static char * BackendClientHostnameBuffer
static int cmp_lbestatus(const void *a, const void *b)
bool pgstat_track_activities
char * pgstat_clip_activity(const char *raw_activity)
uint64 pgstat_get_my_plan_id(void)
static MemoryContext backendStatusSnapContext
const char * pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
static char * BackendActivityBuffer
void pgstat_report_plan_id(uint64 plan_id, bool force)
void BackendStatusShmemInit(void)
static void pgstat_setup_backend_status_context(void)
LocalPgBackendStatus * pgstat_get_local_beentry_by_index(int idx)
void pgstat_report_query_id(uint64 query_id, bool force)
static char * BackendAppnameBuffer
void pgstat_report_activity(BackendState state, const char *cmd_str)
BackendType pgstat_get_backend_type_by_proc_number(ProcNumber procNumber)
void pgstat_report_xact_timestamp(TimestampTz tstamp)
PgBackendStatus * pgstat_get_beentry_by_proc_number(ProcNumber procNumber)
static PgBackendStatus * BackendStatusArray
void pgstat_beinit(void)
void pgstat_bestart_final(void)
Size BackendStatusShmemSize(void)
void pgstat_report_appname(const char *appname)
static Size BackendActivityBufferSize
const char * pgstat_get_backend_current_activity(int pid, bool checkUser)
static void pgstat_read_current_status(void)
int pgstat_track_activity_query_size
BackendState
@ STATE_UNDEFINED
@ STATE_IDLEINTRANSACTION_ABORTED
@ STATE_STARTING
@ STATE_IDLEINTRANSACTION
@ STATE_DISABLED
@ STATE_FASTPATH
@ STATE_RUNNING
#define pgstat_read_activity_complete(before_changecount, after_changecount)
#define PGSTAT_END_WRITE_ACTIVITY(beentry)
#define PGSTAT_BEGIN_WRITE_ACTIVITY(beentry)
#define pgstat_end_read_activity(beentry, after_changecount)
#define pgstat_begin_read_activity(beentry, before_changecount)
bool be_gssapi_get_auth(Port *port)
bool be_gssapi_get_enc(Port *port)
const char * be_gssapi_get_princ(Port *port)
bool be_gssapi_get_delegation(Port *port)
const char * be_tls_get_version(Port *port)
int be_tls_get_cipher_bits(Port *port)
const char * be_tls_get_cipher(Port *port)
void be_tls_get_peer_serial(Port *port, char *ptr, size_t len)
void be_tls_get_peer_issuer_name(Port *port, char *ptr, size_t len)
void be_tls_get_peer_subject_name(Port *port, char *ptr, size_t len)
#define Min(x, y)
Definition: c.h:975
#define unvolatize(underlying_type, expr)
Definition: c.h:1218
uint64_t uint64
Definition: c.h:503
#define MemSet(start, val, len)
Definition: c.h:991
#define UINT64CONST(x)
Definition: c.h:517
size_t Size
Definition: c.h:576
int64 TimestampTz
Definition: timestamp.h:39
int MyProcPid
Definition: globals.c:48
ProcNumber MyProcNumber
Definition: globals.c:91
int MaxBackends
Definition: globals.c:147
TimestampTz MyStartTimestamp
Definition: globals.c:50
struct Port * MyProcPort
Definition: globals.c:52
Oid MyDatabaseId
Definition: globals.c:95
char * application_name
Definition: guc_tables.c:560
Assert(PointerIsAligned(start, uint64))
void on_shmem_exit(pg_on_exit_callback function, Datum arg)
Definition: ipc.c:365
int b
Definition: isn.c:74
int a
Definition: isn.c:73
int i
Definition: isn.c:77
int pg_mbcliplen(const char *mbstr, int len, int limit)
Definition: mbutils.c:1083
static int cliplen(const char *str, int len, int limit)
Definition: mbutils.c:1150
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:1260
MemoryContext TopMemoryContext
Definition: mcxt.c:165
char * pnstrdup(const char *in, Size len)
Definition: mcxt.c:2338
void * MemoryContextAllocHuge(MemoryContext context, Size size)
Definition: mcxt.c:2271
void MemoryContextDelete(MemoryContext context)
Definition: mcxt.c:485
#define AllocSetContextCreate
Definition: memutils.h:149
#define ALLOCSET_SMALL_SIZES
Definition: memutils.h:190
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:123
BackendType
Definition: miscadmin.h:338
@ B_WAL_SENDER
Definition: miscadmin.h:347
@ B_BG_WORKER
Definition: miscadmin.h:346
@ B_BACKEND
Definition: miscadmin.h:342
Oid GetUserId(void)
Definition: miscinit.c:520
Oid GetSessionUserId(void)
Definition: miscinit.c:559
BackendType MyBackendType
Definition: miscinit.c:64
void * arg
#define NAMEDATALEN
const void size_t len
#define pgstat_count_conn_txn_idle_time(n)
Definition: pgstat.h:626
#define pgstat_count_conn_active_time(n)
Definition: pgstat.h:624
int64 PgStat_Counter
Definition: pgstat.h:65
void pgstat_create_backend(ProcNumber procnum)
bool pgstat_tracks_backend_bktype(BackendType bktype)
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
uintptr_t Datum
Definition: postgres.h:69
#define InvalidOid
Definition: postgres_ext.h:35
unsigned int Oid
Definition: postgres_ext.h:30
void ProcNumberGetTransactionIds(ProcNumber procNumber, TransactionId *xid, TransactionId *xmin, int *nsubxid, bool *overflowed)
Definition: procarray.c:3160
#define INVALID_PROC_NUMBER
Definition: procnumber.h:26
int ProcNumber
Definition: procnumber.h:24
Size add_size(Size s1, Size s2)
Definition: shmem.c:493
Size mul_size(Size s1, Size s2)
Definition: shmem.c:510
void * ShmemInitStruct(const char *name, Size size, bool *foundPtr)
Definition: shmem.c:387
PGPROC * MyProc
Definition: proc.c:67
TransactionId backend_xid
PgBackendStatus backendStatus
TransactionId backend_xmin
Definition: proc.h:171
uint32 wait_event_info
Definition: proc.h:288
char gss_princ[NAMEDATALEN]
char ssl_version[NAMEDATALEN]
char ssl_cipher[NAMEDATALEN]
char ssl_client_dn[NAMEDATALEN]
char ssl_client_serial[NAMEDATALEN]
char ssl_issuer_dn[NAMEDATALEN]
BackendType st_backendType
TimestampTz st_state_start_timestamp
TimestampTz st_proc_start_timestamp
PgBackendGSSStatus * st_gssstatus
BackendState st_state
TimestampTz st_activity_start_timestamp
ProgressCommandType st_progress_command
SockAddr st_clientaddr
PgBackendSSLStatus * st_sslstatus
TimestampTz st_xact_start_timestamp
char * st_clienthostname
Oid st_progress_command_target
bool ssl_in_use
Definition: libpq-be.h:208
char * remote_hostname
Definition: libpq-be.h:136
void * gss
Definition: libpq-be.h:202
SockAddr raddr
Definition: libpq-be.h:134
Definition: regguts.h:323
bool superuser(void)
Definition: superuser.c:46
TimestampTz GetCurrentStatementStartTimestamp(void)
Definition: xact.c:879