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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) 2001-2021, PostgreSQL Global Development Group
6  *
7  *
8  * IDENTIFICATION
9  * src/backend/postmaster/backend_status.c
10  * ----------
11  */
12 #include "postgres.h"
13 
14 #include "access/xact.h"
15 #include "libpq/libpq.h"
16 #include "miscadmin.h"
17 #include "pg_trace.h"
18 #include "pgstat.h"
19 #include "port/atomics.h" /* for memory barriers */
20 #include "storage/ipc.h"
21 #include "storage/proc.h" /* for MyProc */
22 #include "storage/sinvaladt.h"
23 #include "utils/ascii.h"
24 #include "utils/backend_status.h"
25 #include "utils/guc.h" /* for application_name */
26 #include "utils/memutils.h"
27 
28 
29 /* ----------
30  * Total number of backends including auxiliary
31  *
32  * We reserve a slot for each possible BackendId, plus one for each
33  * possible auxiliary process type. (This scheme assumes there is not
34  * more than one of any auxiliary process type at a time.) MaxBackends
35  * includes autovacuum workers and background workers as well.
36  * ----------
37  */
38 #define NumBackendStatSlots (MaxBackends + NUM_AUXPROCTYPES)
39 
40 
41 /* ----------
42  * GUC parameters
43  * ----------
44  */
47 
48 
49 /* exposed so that backend_progress.c can access it */
51 
52 
54 static char *BackendAppnameBuffer = NULL;
55 static char *BackendClientHostnameBuffer = NULL;
56 static char *BackendActivityBuffer = NULL;
58 #ifdef USE_SSL
59 static PgBackendSSLStatus *BackendSslStatusBuffer = NULL;
60 #endif
61 #ifdef ENABLE_GSS
62 static PgBackendGSSStatus *BackendGssStatusBuffer = NULL;
63 #endif
64 
65 
66 /* Status for backends including auxiliary */
68 
69 /* Total number of backends including auxiliary */
70 static int localNumBackends = 0;
71 
73 
74 
75 static void pgstat_beshutdown_hook(int code, Datum arg);
76 static void pgstat_read_current_status(void);
77 static void pgstat_setup_backend_status_context(void);
78 
79 
80 /*
81  * Report shared-memory space needed by CreateSharedBackendStatus.
82  */
83 Size
85 {
86  Size size;
87 
88  /* BackendStatusArray: */
90  /* BackendAppnameBuffer: */
91  size = add_size(size,
93  /* BackendClientHostnameBuffer: */
94  size = add_size(size,
96  /* BackendActivityBuffer: */
97  size = add_size(size,
99 #ifdef USE_SSL
100  /* BackendSslStatusBuffer: */
101  size = add_size(size,
103 #endif
104 #ifdef ENABLE_GSS
105  /* BackendGssStatusBuffer: */
106  size = add_size(size,
108 #endif
109  return size;
110 }
111 
112 /*
113  * Initialize the shared status array and several string buffers
114  * during postmaster startup.
115  */
116 void
118 {
119  Size size;
120  bool found;
121  int i;
122  char *buffer;
123 
124  /* Create or attach to the shared array */
126  BackendStatusArray = (PgBackendStatus *)
127  ShmemInitStruct("Backend Status Array", size, &found);
128 
129  if (!found)
130  {
131  /*
132  * We're the first - initialize.
133  */
134  MemSet(BackendStatusArray, 0, size);
135  }
136 
137  /* Create or attach to the shared appname buffer */
139  BackendAppnameBuffer = (char *)
140  ShmemInitStruct("Backend Application Name Buffer", size, &found);
141 
142  if (!found)
143  {
144  MemSet(BackendAppnameBuffer, 0, size);
145 
146  /* Initialize st_appname pointers. */
147  buffer = BackendAppnameBuffer;
148  for (i = 0; i < NumBackendStatSlots; i++)
149  {
150  BackendStatusArray[i].st_appname = buffer;
151  buffer += NAMEDATALEN;
152  }
153  }
154 
155  /* Create or attach to the shared client hostname buffer */
157  BackendClientHostnameBuffer = (char *)
158  ShmemInitStruct("Backend Client Host Name Buffer", size, &found);
159 
160  if (!found)
161  {
163 
164  /* Initialize st_clienthostname pointers. */
166  for (i = 0; i < NumBackendStatSlots; i++)
167  {
168  BackendStatusArray[i].st_clienthostname = buffer;
169  buffer += NAMEDATALEN;
170  }
171  }
172 
173  /* Create or attach to the shared activity buffer */
176  BackendActivityBuffer = (char *)
177  ShmemInitStruct("Backend Activity Buffer",
179  &found);
180 
181  if (!found)
182  {
184 
185  /* Initialize st_activity pointers. */
186  buffer = BackendActivityBuffer;
187  for (i = 0; i < NumBackendStatSlots; i++)
188  {
189  BackendStatusArray[i].st_activity_raw = buffer;
191  }
192  }
193 
194 #ifdef USE_SSL
195  /* Create or attach to the shared SSL status buffer */
197  BackendSslStatusBuffer = (PgBackendSSLStatus *)
198  ShmemInitStruct("Backend SSL Status Buffer", size, &found);
199 
200  if (!found)
201  {
202  PgBackendSSLStatus *ptr;
203 
204  MemSet(BackendSslStatusBuffer, 0, size);
205 
206  /* Initialize st_sslstatus pointers. */
207  ptr = BackendSslStatusBuffer;
208  for (i = 0; i < NumBackendStatSlots; i++)
209  {
210  BackendStatusArray[i].st_sslstatus = ptr;
211  ptr++;
212  }
213  }
214 #endif
215 
216 #ifdef ENABLE_GSS
217  /* Create or attach to the shared GSSAPI status buffer */
219  BackendGssStatusBuffer = (PgBackendGSSStatus *)
220  ShmemInitStruct("Backend GSS Status Buffer", size, &found);
221 
222  if (!found)
223  {
224  PgBackendGSSStatus *ptr;
225 
226  MemSet(BackendGssStatusBuffer, 0, size);
227 
228  /* Initialize st_gssstatus pointers. */
229  ptr = BackendGssStatusBuffer;
230  for (i = 0; i < NumBackendStatSlots; i++)
231  {
232  BackendStatusArray[i].st_gssstatus = ptr;
233  ptr++;
234  }
235  }
236 #endif
237 }
238 
239 /*
240  * Initialize pgstats backend activity state, and set up our on-proc-exit
241  * hook. Called from InitPostgres and AuxiliaryProcessMain. For auxiliary
242  * process, MyBackendId is invalid. Otherwise, MyBackendId must be set, but we
243  * must not have started any transaction yet (since the exit hook must run
244  * after the last transaction exit).
245  *
246  * NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
247  */
248 void
250 {
251  /* Initialize MyBEEntry */
253  {
255  MyBEEntry = &BackendStatusArray[MyBackendId - 1];
256  }
257  else
258  {
259  /* Must be an auxiliary process */
261 
262  /*
263  * Assign the MyBEEntry for an auxiliary process. Since it doesn't
264  * have a BackendId, the slot is statically allocated based on the
265  * auxiliary process type (MyAuxProcType). Backends use slots indexed
266  * in the range from 1 to MaxBackends (inclusive), so we use
267  * MaxBackends + AuxBackendType + 1 as the index of the slot for an
268  * auxiliary process.
269  */
270  MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
271  }
272 
273  /* Set up a process-exit hook to clean up */
275 }
276 
277 
278 /* ----------
279  * pgstat_bestart() -
280  *
281  * Initialize this backend's entry in the PgBackendStatus array.
282  * Called from InitPostgres.
283  *
284  * Apart from auxiliary processes, MyBackendId, MyDatabaseId,
285  * session userid, and application_name must be set for a
286  * backend (hence, this cannot be combined with pgbestat_beinit).
287  * Note also that we must be inside a transaction if this isn't an aux
288  * process, as we may need to do encoding conversion on some strings.
289  * ----------
290  */
291 void
293 {
294  volatile PgBackendStatus *vbeentry = MyBEEntry;
295  PgBackendStatus lbeentry;
296 #ifdef USE_SSL
297  PgBackendSSLStatus lsslstatus;
298 #endif
299 #ifdef ENABLE_GSS
300  PgBackendGSSStatus lgssstatus;
301 #endif
302 
303  /* pgstats state must be initialized from pgstat_beinit() */
304  Assert(vbeentry != NULL);
305 
306  /*
307  * To minimize the time spent modifying the PgBackendStatus entry, and
308  * avoid risk of errors inside the critical section, we first copy the
309  * shared-memory struct to a local variable, then modify the data in the
310  * local variable, then copy the local variable back to shared memory.
311  * Only the last step has to be inside the critical section.
312  *
313  * Most of the data we copy from shared memory is just going to be
314  * overwritten, but the struct's not so large that it's worth the
315  * maintenance hassle to copy only the needful fields.
316  */
317  memcpy(&lbeentry,
318  unvolatize(PgBackendStatus *, vbeentry),
319  sizeof(PgBackendStatus));
320 
321  /* These structs can just start from zeroes each time, though */
322 #ifdef USE_SSL
323  memset(&lsslstatus, 0, sizeof(lsslstatus));
324 #endif
325 #ifdef ENABLE_GSS
326  memset(&lgssstatus, 0, sizeof(lgssstatus));
327 #endif
328 
329  /*
330  * Now fill in all the fields of lbeentry, except for strings that are
331  * out-of-line data. Those have to be handled separately, below.
332  */
333  lbeentry.st_procpid = MyProcPid;
334  lbeentry.st_backendType = MyBackendType;
336  lbeentry.st_activity_start_timestamp = 0;
337  lbeentry.st_state_start_timestamp = 0;
338  lbeentry.st_xact_start_timestamp = 0;
339  lbeentry.st_databaseid = MyDatabaseId;
340 
341  /* We have userid for client-backends, wal-sender and bgworker processes */
342  if (lbeentry.st_backendType == B_BACKEND
343  || lbeentry.st_backendType == B_WAL_SENDER
344  || lbeentry.st_backendType == B_BG_WORKER)
345  lbeentry.st_userid = GetSessionUserId();
346  else
347  lbeentry.st_userid = InvalidOid;
348 
349  /*
350  * We may not have a MyProcPort (eg, if this is the autovacuum process).
351  * If so, use all-zeroes client address, which is dealt with specially in
352  * pg_stat_get_backend_client_addr and pg_stat_get_backend_client_port.
353  */
354  if (MyProcPort)
355  memcpy(&lbeentry.st_clientaddr, &MyProcPort->raddr,
356  sizeof(lbeentry.st_clientaddr));
357  else
358  MemSet(&lbeentry.st_clientaddr, 0, sizeof(lbeentry.st_clientaddr));
359 
360 #ifdef USE_SSL
362  {
363  lbeentry.st_ssl = true;
370  }
371  else
372  {
373  lbeentry.st_ssl = false;
374  }
375 #else
376  lbeentry.st_ssl = false;
377 #endif
378 
379 #ifdef ENABLE_GSS
380  if (MyProcPort && MyProcPort->gss != NULL)
381  {
382  const char *princ = be_gssapi_get_princ(MyProcPort);
383 
384  lbeentry.st_gss = true;
385  lgssstatus.gss_auth = be_gssapi_get_auth(MyProcPort);
386  lgssstatus.gss_enc = be_gssapi_get_enc(MyProcPort);
387  if (princ)
388  strlcpy(lgssstatus.gss_princ, princ, NAMEDATALEN);
389  }
390  else
391  {
392  lbeentry.st_gss = false;
393  }
394 #else
395  lbeentry.st_gss = false;
396 #endif
397 
398  lbeentry.st_state = STATE_UNDEFINED;
401  lbeentry.st_query_id = UINT64CONST(0);
402 
403  /*
404  * we don't zero st_progress_param here to save cycles; nobody should
405  * examine it until st_progress_command has been set to something other
406  * than PROGRESS_COMMAND_INVALID
407  */
408 
409  /*
410  * We're ready to enter the critical section that fills the shared-memory
411  * status entry. We follow the protocol of bumping st_changecount before
412  * and after; and make sure it's even afterwards. We use a volatile
413  * pointer here to ensure the compiler doesn't try to get cute.
414  */
415  PGSTAT_BEGIN_WRITE_ACTIVITY(vbeentry);
416 
417  /* make sure we'll memcpy the same st_changecount back */
418  lbeentry.st_changecount = vbeentry->st_changecount;
419 
420  memcpy(unvolatize(PgBackendStatus *, vbeentry),
421  &lbeentry,
422  sizeof(PgBackendStatus));
423 
424  /*
425  * We can write the out-of-line strings and structs using the pointers
426  * that are in lbeentry; this saves some de-volatilizing messiness.
427  */
428  lbeentry.st_appname[0] = '\0';
431  NAMEDATALEN);
432  else
433  lbeentry.st_clienthostname[0] = '\0';
434  lbeentry.st_activity_raw[0] = '\0';
435  /* Also make sure the last byte in each string area is always 0 */
436  lbeentry.st_appname[NAMEDATALEN - 1] = '\0';
437  lbeentry.st_clienthostname[NAMEDATALEN - 1] = '\0';
439 
440 #ifdef USE_SSL
441  memcpy(lbeentry.st_sslstatus, &lsslstatus, sizeof(PgBackendSSLStatus));
442 #endif
443 #ifdef ENABLE_GSS
444  memcpy(lbeentry.st_gssstatus, &lgssstatus, sizeof(PgBackendGSSStatus));
445 #endif
446 
447  PGSTAT_END_WRITE_ACTIVITY(vbeentry);
448 
449  /* Update app name to current GUC setting */
450  if (application_name)
452 }
453 
454 /*
455  * Clear out our entry in the PgBackendStatus array.
456  */
457 static void
459 {
460  volatile PgBackendStatus *beentry = MyBEEntry;
461 
462  /*
463  * Clear my status entry, following the protocol of bumping st_changecount
464  * before and after. We use a volatile pointer here to ensure the
465  * compiler doesn't try to get cute.
466  */
468 
469  beentry->st_procpid = 0; /* mark invalid */
470 
471  PGSTAT_END_WRITE_ACTIVITY(beentry);
472 
473  /* so that functions can check if backend_status.c is up via MyBEEntry */
474  MyBEEntry = NULL;
475 }
476 
477 /*
478  * Discard any data collected in the current transaction. Any subsequent
479  * request will cause new snapshots to be read.
480  *
481  * This is also invoked during transaction commit or abort to discard the
482  * no-longer-wanted snapshot.
483  */
484 void
486 {
487  /* Release memory, if any was allocated */
488  if (backendStatusSnapContext)
489  {
490  MemoryContextDelete(backendStatusSnapContext);
491  backendStatusSnapContext = NULL;
492  }
493 
494  /* Reset variables */
495  localBackendStatusTable = NULL;
496  localNumBackends = 0;
497 }
498 
499 static void
501 {
502  if (!backendStatusSnapContext)
503  backendStatusSnapContext = AllocSetContextCreate(TopMemoryContext,
504  "Backend Status Snapshot",
506 }
507 
508 
509 /* ----------
510  * pgstat_report_activity() -
511  *
512  * Called from tcop/postgres.c to report what the backend is actually doing
513  * (but note cmd_str can be NULL for certain cases).
514  *
515  * All updates of the status entry follow the protocol of bumping
516  * st_changecount before and after. We use a volatile pointer here to
517  * ensure the compiler doesn't try to get cute.
518  * ----------
519  */
520 void
522 {
523  volatile PgBackendStatus *beentry = MyBEEntry;
524  TimestampTz start_timestamp;
525  TimestampTz current_timestamp;
526  int len = 0;
527 
528  TRACE_POSTGRESQL_STATEMENT_STATUS(cmd_str);
529 
530  if (!beentry)
531  return;
532 
534  {
535  if (beentry->st_state != STATE_DISABLED)
536  {
537  volatile PGPROC *proc = MyProc;
538 
539  /*
540  * track_activities is disabled, but we last reported a
541  * non-disabled state. As our final update, change the state and
542  * clear fields we will not be updating anymore.
543  */
545  beentry->st_state = STATE_DISABLED;
546  beentry->st_state_start_timestamp = 0;
547  beentry->st_activity_raw[0] = '\0';
548  beentry->st_activity_start_timestamp = 0;
549  /* st_xact_start_timestamp and wait_event_info are also disabled */
550  beentry->st_xact_start_timestamp = 0;
551  beentry->st_query_id = UINT64CONST(0);
552  proc->wait_event_info = 0;
553  PGSTAT_END_WRITE_ACTIVITY(beentry);
554  }
555  return;
556  }
557 
558  /*
559  * To minimize the time spent modifying the entry, and avoid risk of
560  * errors inside the critical section, fetch all the needed data first.
561  */
562  start_timestamp = GetCurrentStatementStartTimestamp();
563  if (cmd_str != NULL)
564  {
565  /*
566  * Compute length of to-be-stored string unaware of multi-byte
567  * characters. For speed reasons that'll get corrected on read, rather
568  * than computed every write.
569  */
570  len = Min(strlen(cmd_str), pgstat_track_activity_query_size - 1);
571  }
572  current_timestamp = GetCurrentTimestamp();
573 
574  /*
575  * If the state has changed from "active" or "idle in transaction",
576  * calculate the duration.
577  */
578  if ((beentry->st_state == STATE_RUNNING ||
579  beentry->st_state == STATE_FASTPATH ||
580  beentry->st_state == STATE_IDLEINTRANSACTION ||
582  state != beentry->st_state)
583  {
584  long secs;
585  int usecs;
586 
588  current_timestamp,
589  &secs, &usecs);
590 
591  if (beentry->st_state == STATE_RUNNING ||
592  beentry->st_state == STATE_FASTPATH)
593  pgstat_count_conn_active_time((PgStat_Counter) secs * 1000000 + usecs);
594  else
595  pgstat_count_conn_txn_idle_time((PgStat_Counter) secs * 1000000 + usecs);
596  }
597 
598  /*
599  * Now update the status entry
600  */
602 
603  beentry->st_state = state;
604  beentry->st_state_start_timestamp = current_timestamp;
605 
606  /*
607  * If a new query is started, we reset the query identifier as it'll only
608  * be known after parse analysis, to avoid reporting last query's
609  * identifier.
610  */
611  if (state == STATE_RUNNING)
612  beentry->st_query_id = UINT64CONST(0);
613 
614  if (cmd_str != NULL)
615  {
616  memcpy((char *) beentry->st_activity_raw, cmd_str, len);
617  beentry->st_activity_raw[len] = '\0';
618  beentry->st_activity_start_timestamp = start_timestamp;
619  }
620 
621  PGSTAT_END_WRITE_ACTIVITY(beentry);
622 }
623 
624 /* --------
625  * pgstat_report_query_id() -
626  *
627  * Called to update top-level query identifier.
628  * --------
629  */
630 void
631 pgstat_report_query_id(uint64 query_id, bool force)
632 {
633  volatile PgBackendStatus *beentry = MyBEEntry;
634 
635  /*
636  * if track_activities is disabled, st_query_id should already have been
637  * reset
638  */
639  if (!beentry || !pgstat_track_activities)
640  return;
641 
642  /*
643  * We only report the top-level query identifiers. The stored query_id is
644  * reset when a backend calls pgstat_report_activity(STATE_RUNNING), or
645  * with an explicit call to this function using the force flag. If the
646  * saved query identifier is not zero it means that it's not a top-level
647  * command, so ignore the one provided unless it's an explicit call to
648  * reset the identifier.
649  */
650  if (beentry->st_query_id != 0 && !force)
651  return;
652 
653  /*
654  * Update my status entry, following the protocol of bumping
655  * st_changecount before and after. We use a volatile pointer here to
656  * ensure the compiler doesn't try to get cute.
657  */
659  beentry->st_query_id = query_id;
660  PGSTAT_END_WRITE_ACTIVITY(beentry);
661 }
662 
663 
664 /* ----------
665  * pgstat_report_appname() -
666  *
667  * Called to update our application name.
668  * ----------
669  */
670 void
671 pgstat_report_appname(const char *appname)
672 {
673  volatile PgBackendStatus *beentry = MyBEEntry;
674  int len;
675 
676  if (!beentry)
677  return;
678 
679  /* This should be unnecessary if GUC did its job, but be safe */
680  len = pg_mbcliplen(appname, strlen(appname), NAMEDATALEN - 1);
681 
682  /*
683  * Update my status entry, following the protocol of bumping
684  * st_changecount before and after. We use a volatile pointer here to
685  * ensure the compiler doesn't try to get cute.
686  */
688 
689  memcpy((char *) beentry->st_appname, appname, len);
690  beentry->st_appname[len] = '\0';
691 
692  PGSTAT_END_WRITE_ACTIVITY(beentry);
693 }
694 
695 /*
696  * Report current transaction start timestamp as the specified value.
697  * Zero means there is no active transaction.
698  */
699 void
701 {
702  volatile PgBackendStatus *beentry = MyBEEntry;
703 
704  if (!pgstat_track_activities || !beentry)
705  return;
706 
707  /*
708  * Update my status entry, following the protocol of bumping
709  * st_changecount before and after. We use a volatile pointer here to
710  * ensure the compiler doesn't try to get cute.
711  */
713 
714  beentry->st_xact_start_timestamp = tstamp;
715 
716  PGSTAT_END_WRITE_ACTIVITY(beentry);
717 }
718 
719 /* ----------
720  * pgstat_read_current_status() -
721  *
722  * Copy the current contents of the PgBackendStatus array to local memory,
723  * if not already done in this transaction.
724  * ----------
725  */
726 static void
728 {
729  volatile PgBackendStatus *beentry;
730  LocalPgBackendStatus *localtable;
731  LocalPgBackendStatus *localentry;
732  char *localappname,
733  *localclienthostname,
734  *localactivity;
735 #ifdef USE_SSL
736  PgBackendSSLStatus *localsslstatus;
737 #endif
738 #ifdef ENABLE_GSS
739  PgBackendGSSStatus *localgssstatus;
740 #endif
741  int i;
742 
743  if (localBackendStatusTable)
744  return; /* already done */
745 
747 
748  /*
749  * Allocate storage for local copy of state data. We can presume that
750  * none of these requests overflow size_t, because we already calculated
751  * the same values using mul_size during shmem setup. However, with
752  * probably-silly values of pgstat_track_activity_query_size and
753  * max_connections, the localactivity buffer could exceed 1GB, so use
754  * "huge" allocation for that one.
755  */
756  localtable = (LocalPgBackendStatus *)
757  MemoryContextAlloc(backendStatusSnapContext,
759  localappname = (char *)
760  MemoryContextAlloc(backendStatusSnapContext,
762  localclienthostname = (char *)
763  MemoryContextAlloc(backendStatusSnapContext,
764  NAMEDATALEN * NumBackendStatSlots);
765  localactivity = (char *)
766  MemoryContextAllocHuge(backendStatusSnapContext,
767  pgstat_track_activity_query_size * NumBackendStatSlots);
768 #ifdef USE_SSL
769  localsslstatus = (PgBackendSSLStatus *)
770  MemoryContextAlloc(backendStatusSnapContext,
772 #endif
773 #ifdef ENABLE_GSS
774  localgssstatus = (PgBackendGSSStatus *)
775  MemoryContextAlloc(backendStatusSnapContext,
777 #endif
778 
779  localNumBackends = 0;
780 
781  beentry = BackendStatusArray;
782  localentry = localtable;
783  for (i = 1; i <= NumBackendStatSlots; i++)
784  {
785  /*
786  * Follow the protocol of retrying if st_changecount changes while we
787  * copy the entry, or if it's odd. (The check for odd is needed to
788  * cover the case where we are able to completely copy the entry while
789  * the source backend is between increment steps.) We use a volatile
790  * pointer here to ensure the compiler doesn't try to get cute.
791  */
792  for (;;)
793  {
794  int before_changecount;
795  int after_changecount;
796 
797  pgstat_begin_read_activity(beentry, before_changecount);
798 
799  localentry->backendStatus.st_procpid = beentry->st_procpid;
800  /* Skip all the data-copying work if entry is not in use */
801  if (localentry->backendStatus.st_procpid > 0)
802  {
803  memcpy(&localentry->backendStatus, unvolatize(PgBackendStatus *, beentry), sizeof(PgBackendStatus));
804 
805  /*
806  * For each PgBackendStatus field that is a pointer, copy the
807  * pointed-to data, then adjust the local copy of the pointer
808  * field to point at the local copy of the data.
809  *
810  * strcpy is safe even if the string is modified concurrently,
811  * because there's always a \0 at the end of the buffer.
812  */
813  strcpy(localappname, (char *) beentry->st_appname);
814  localentry->backendStatus.st_appname = localappname;
815  strcpy(localclienthostname, (char *) beentry->st_clienthostname);
816  localentry->backendStatus.st_clienthostname = localclienthostname;
817  strcpy(localactivity, (char *) beentry->st_activity_raw);
818  localentry->backendStatus.st_activity_raw = localactivity;
819 #ifdef USE_SSL
820  if (beentry->st_ssl)
821  {
822  memcpy(localsslstatus, beentry->st_sslstatus, sizeof(PgBackendSSLStatus));
823  localentry->backendStatus.st_sslstatus = localsslstatus;
824  }
825 #endif
826 #ifdef ENABLE_GSS
827  if (beentry->st_gss)
828  {
829  memcpy(localgssstatus, beentry->st_gssstatus, sizeof(PgBackendGSSStatus));
830  localentry->backendStatus.st_gssstatus = localgssstatus;
831  }
832 #endif
833  }
834 
835  pgstat_end_read_activity(beentry, after_changecount);
836 
837  if (pgstat_read_activity_complete(before_changecount,
838  after_changecount))
839  break;
840 
841  /* Make sure we can break out of loop if stuck... */
843  }
844 
845  beentry++;
846  /* Only valid entries get included into the local array */
847  if (localentry->backendStatus.st_procpid > 0)
848  {
850  &localentry->backend_xid,
851  &localentry->backend_xmin);
852 
853  localentry++;
854  localappname += NAMEDATALEN;
855  localclienthostname += NAMEDATALEN;
856  localactivity += pgstat_track_activity_query_size;
857 #ifdef USE_SSL
858  localsslstatus++;
859 #endif
860 #ifdef ENABLE_GSS
861  localgssstatus++;
862 #endif
864  }
865  }
866 
867  /* Set the pointer only after completion of a valid table */
868  localBackendStatusTable = localtable;
869 }
870 
871 
872 /* ----------
873  * pgstat_get_backend_current_activity() -
874  *
875  * Return a string representing the current activity of the backend with
876  * the specified PID. This looks directly at the BackendStatusArray,
877  * and so will provide current information regardless of the age of our
878  * transaction's snapshot of the status array.
879  *
880  * It is the caller's responsibility to invoke this only for backends whose
881  * state is expected to remain stable while the result is in use. The
882  * only current use is in deadlock reporting, where we can expect that
883  * the target backend is blocked on a lock. (There are corner cases
884  * where the target's wait could get aborted while we are looking at it,
885  * but the very worst consequence is to return a pointer to a string
886  * that's been changed, so we won't worry too much.)
887  *
888  * Note: return strings for special cases match pg_stat_get_backend_activity.
889  * ----------
890  */
891 const char *
892 pgstat_get_backend_current_activity(int pid, bool checkUser)
893 {
894  PgBackendStatus *beentry;
895  int i;
896 
897  beentry = BackendStatusArray;
898  for (i = 1; i <= MaxBackends; i++)
899  {
900  /*
901  * Although we expect the target backend's entry to be stable, that
902  * doesn't imply that anyone else's is. To avoid identifying the
903  * wrong backend, while we check for a match to the desired PID we
904  * must follow the protocol of retrying if st_changecount changes
905  * while we examine the entry, or if it's odd. (This might be
906  * unnecessary, since fetching or storing an int is almost certainly
907  * atomic, but let's play it safe.) We use a volatile pointer here to
908  * ensure the compiler doesn't try to get cute.
909  */
910  volatile PgBackendStatus *vbeentry = beentry;
911  bool found;
912 
913  for (;;)
914  {
915  int before_changecount;
916  int after_changecount;
917 
918  pgstat_begin_read_activity(vbeentry, before_changecount);
919 
920  found = (vbeentry->st_procpid == pid);
921 
922  pgstat_end_read_activity(vbeentry, after_changecount);
923 
924  if (pgstat_read_activity_complete(before_changecount,
925  after_changecount))
926  break;
927 
928  /* Make sure we can break out of loop if stuck... */
930  }
931 
932  if (found)
933  {
934  /* Now it is safe to use the non-volatile pointer */
935  if (checkUser && !superuser() && beentry->st_userid != GetUserId())
936  return "<insufficient privilege>";
937  else if (*(beentry->st_activity_raw) == '\0')
938  return "<command string not enabled>";
939  else
940  {
941  /* this'll leak a bit of memory, but that seems acceptable */
942  return pgstat_clip_activity(beentry->st_activity_raw);
943  }
944  }
945 
946  beentry++;
947  }
948 
949  /* If we get here, caller is in error ... */
950  return "<backend information not available>";
951 }
952 
953 /* ----------
954  * pgstat_get_crashed_backend_activity() -
955  *
956  * Return a string representing the current activity of the backend with
957  * the specified PID. Like the function above, but reads shared memory with
958  * the expectation that it may be corrupt. On success, copy the string
959  * into the "buffer" argument and return that pointer. On failure,
960  * return NULL.
961  *
962  * This function is only intended to be used by the postmaster to report the
963  * query that crashed a backend. In particular, no attempt is made to
964  * follow the correct concurrency protocol when accessing the
965  * BackendStatusArray. But that's OK, in the worst case we'll return a
966  * corrupted message. We also must take care not to trip on ereport(ERROR).
967  * ----------
968  */
969 const char *
970 pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
971 {
972  volatile PgBackendStatus *beentry;
973  int i;
974 
975  beentry = BackendStatusArray;
976 
977  /*
978  * We probably shouldn't get here before shared memory has been set up,
979  * but be safe.
980  */
981  if (beentry == NULL || BackendActivityBuffer == NULL)
982  return NULL;
983 
984  for (i = 1; i <= MaxBackends; i++)
985  {
986  if (beentry->st_procpid == pid)
987  {
988  /* Read pointer just once, so it can't change after validation */
989  const char *activity = beentry->st_activity_raw;
990  const char *activity_last;
991 
992  /*
993  * We mustn't access activity string before we verify that it
994  * falls within the BackendActivityBuffer. To make sure that the
995  * entire string including its ending is contained within the
996  * buffer, subtract one activity length from the buffer size.
997  */
1000 
1001  if (activity < BackendActivityBuffer ||
1002  activity > activity_last)
1003  return NULL;
1004 
1005  /* If no string available, no point in a report */
1006  if (activity[0] == '\0')
1007  return NULL;
1008 
1009  /*
1010  * Copy only ASCII-safe characters so we don't run into encoding
1011  * problems when reporting the message; and be sure not to run off
1012  * the end of memory. As only ASCII characters are reported, it
1013  * doesn't seem necessary to perform multibyte aware clipping.
1014  */
1015  ascii_safe_strlcpy(buffer, activity,
1016  Min(buflen, pgstat_track_activity_query_size));
1017 
1018  return buffer;
1019  }
1020 
1021  beentry++;
1022  }
1023 
1024  /* PID not found */
1025  return NULL;
1026 }
1027 
1028 /* ----------
1029  * pgstat_get_my_query_id() -
1030  *
1031  * Return current backend's query identifier.
1032  */
1033 uint64
1035 {
1036  if (!MyBEEntry)
1037  return 0;
1038 
1039  /*
1040  * There's no need for a lock around pgstat_begin_read_activity /
1041  * pgstat_end_read_activity here as it's only called from
1042  * pg_stat_get_activity which is already protected, or from the same
1043  * backend which means that there won't be concurrent writes.
1044  */
1045  return MyBEEntry->st_query_id;
1046 }
1047 
1048 
1049 /* ----------
1050  * pgstat_fetch_stat_beentry() -
1051  *
1052  * Support function for the SQL-callable pgstat* functions. Returns
1053  * our local copy of the current-activity entry for one backend.
1054  *
1055  * NB: caller is responsible for a check if the user is permitted to see
1056  * this info (especially the querystring).
1057  * ----------
1058  */
1061 {
1063 
1064  if (beid < 1 || beid > localNumBackends)
1065  return NULL;
1066 
1067  return &localBackendStatusTable[beid - 1].backendStatus;
1068 }
1069 
1070 
1071 /* ----------
1072  * pgstat_fetch_stat_local_beentry() -
1073  *
1074  * Like pgstat_fetch_stat_beentry() but with locally computed additions (like
1075  * xid and xmin values of the backend)
1076  *
1077  * NB: caller is responsible for a check if the user is permitted to see
1078  * this info (especially the querystring).
1079  * ----------
1080  */
1083 {
1085 
1086  if (beid < 1 || beid > localNumBackends)
1087  return NULL;
1088 
1089  return &localBackendStatusTable[beid - 1];
1090 }
1091 
1092 
1093 /* ----------
1094  * pgstat_fetch_stat_numbackends() -
1095  *
1096  * Support function for the SQL-callable pgstat* functions. Returns
1097  * the maximum current backend id.
1098  * ----------
1099  */
1100 int
1102 {
1104 
1105  return localNumBackends;
1106 }
1107 
1108 /*
1109  * Convert a potentially unsafely truncated activity string (see
1110  * PgBackendStatus.st_activity_raw's documentation) into a correctly truncated
1111  * one.
1112  *
1113  * The returned string is allocated in the caller's memory context and may be
1114  * freed.
1115  */
1116 char *
1117 pgstat_clip_activity(const char *raw_activity)
1118 {
1119  char *activity;
1120  int rawlen;
1121  int cliplen;
1122 
1123  /*
1124  * Some callers, like pgstat_get_backend_current_activity(), do not
1125  * guarantee that the buffer isn't concurrently modified. We try to take
1126  * care that the buffer is always terminated by a NUL byte regardless, but
1127  * let's still be paranoid about the string's length. In those cases the
1128  * underlying buffer is guaranteed to be pgstat_track_activity_query_size
1129  * large.
1130  */
1131  activity = pnstrdup(raw_activity, pgstat_track_activity_query_size - 1);
1132 
1133  /* now double-guaranteed to be NUL terminated */
1134  rawlen = strlen(activity);
1135 
1136  /*
1137  * All supported server-encodings make it possible to determine the length
1138  * of a multi-byte character from its first byte (this is not the case for
1139  * client encodings, see GB18030). As st_activity is always stored using
1140  * server encoding, this allows us to perform multi-byte aware truncation,
1141  * even if the string earlier was truncated in the middle of a multi-byte
1142  * character.
1143  */
1144  cliplen = pg_mbcliplen(activity, rawlen,
1146 
1147  activity[cliplen] = '\0';
1148 
1149  return activity;
1150 }
char ssl_issuer_dn[NAMEDATALEN]
char gss_princ[NAMEDATALEN]
PgBackendStatus * MyBEEntry
static PgBackendStatus * BackendStatusArray
char ssl_cipher[NAMEDATALEN]
char * pgstat_clip_activity(const char *raw_activity)
void MemoryContextDelete(MemoryContext context)
Definition: mcxt.c:218
#define AllocSetContextCreate
Definition: memutils.h:173
Oid st_progress_command_target
int64 PgStat_Counter
Definition: pgstat.h:92
int MyProcPid
Definition: globals.c:43
BackendId MyBackendId
Definition: globals.c:84
char * pnstrdup(const char *in, Size len)
Definition: mcxt.c:1310
struct Port * MyProcPort
Definition: globals.c:46
const char * be_gssapi_get_princ(Port *port)
void pgstat_report_appname(const char *appname)
uint32 wait_event_info
Definition: proc.h:226
PgBackendStatus * pgstat_fetch_stat_beentry(int beid)
static MemoryContext backendStatusSnapContext
Oid GetUserId(void)
Definition: miscinit.c:495
BackendType MyBackendType
Definition: miscinit.c:62
TimestampTz st_activity_start_timestamp
TimestampTz GetCurrentTimestamp(void)
Definition: timestamp.c:1580
PGPROC * MyProc
Definition: proc.c:68
int64 TimestampTz
Definition: timestamp.h:39
#define ALLOCSET_SMALL_SIZES
Definition: memutils.h:205
#define pgstat_count_conn_active_time(n)
Definition: pgstat.h:1089
static void pgstat_setup_backend_status_context(void)
#define Min(x, y)
Definition: c.h:986
char ssl_client_dn[NAMEDATALEN]
const char * pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
TransactionId backend_xmin
char ssl_version[NAMEDATALEN]
static LocalPgBackendStatus * localBackendStatusTable
SockAddr st_clientaddr
bool superuser(void)
Definition: superuser.c:46
#define MemSet(start, val, len)
Definition: c.h:1008
bool ssl_in_use
Definition: libpq-be.h:209
int pgstat_track_activity_query_size
void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz)
Definition: ascii.c:173
Size BackendStatusShmemSize(void)
ProgressCommandType st_progress_command
void pgstat_bestart(void)
char ssl_client_serial[NAMEDATALEN]
BackendState st_state
char * st_clienthostname
Oid GetSessionUserId(void)
Definition: miscinit.c:529
int pgstat_fetch_stat_numbackends(void)
static int localNumBackends
#define NAMEDATALEN
void pgstat_report_xact_timestamp(TimestampTz tstamp)
char * remote_hostname
Definition: libpq-be.h:133
SockAddr raddr
Definition: libpq-be.h:131
TransactionId backend_xid
void * ShmemInitStruct(const char *name, Size size, bool *foundPtr)
Definition: shmem.c:396
int pg_mbcliplen(const char *mbstr, int len, int limit)
Definition: mbutils.c:1026
int MaxBackends
Definition: globals.c:139
AuxProcType MyAuxProcType
Definition: auxprocess.c:45
#define PGSTAT_BEGIN_WRITE_ACTIVITY(beentry)
void on_shmem_exit(pg_on_exit_callback function, Datum arg)
Definition: ipc.c:361
void * MemoryContextAllocHuge(MemoryContext context, Size size)
Definition: mcxt.c:1218
void pgstat_beinit(void)
TimestampTz st_state_start_timestamp
MemoryContext TopMemoryContext
Definition: mcxt.c:48
#define pgstat_count_conn_txn_idle_time(n)
Definition: pgstat.h:1091
#define pgstat_end_read_activity(beentry, after_changecount)
bool be_gssapi_get_enc(Port *port)
Size mul_size(Size s1, Size s2)
Definition: shmem.c:519
#define InvalidBackendId
Definition: backendid.h:23
PgBackendStatus backendStatus
TimestampTz MyStartTimestamp
Definition: globals.c:45
int be_tls_get_cipher_bits(Port *port)
uintptr_t Datum
Definition: postgres.h:411
void BackendIdGetTransactionIds(int backendID, TransactionId *xid, TransactionId *xmin)
Definition: sinvaladt.c:403
Size add_size(Size s1, Size s2)
Definition: shmem.c:502
uint64 pgstat_get_my_query_id(void)
Oid MyDatabaseId
Definition: globals.c:88
BackendType st_backendType
static char * BackendActivityBuffer
#define InvalidOid
Definition: postgres_ext.h:36
void pgstat_report_query_id(uint64 query_id, bool force)
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
BackendState
#define Assert(condition)
Definition: c.h:804
Definition: regguts.h:317
static int cliplen(const char *str, int len, int limit)
Definition: mbutils.c:1093
static void pgstat_beshutdown_hook(int code, Datum arg)
static Size BackendActivityBufferSize
const char * pgstat_get_backend_current_activity(int pid, bool checkUser)
size_t Size
Definition: c.h:540
static char * BackendAppnameBuffer
const char * be_tls_get_version(Port *port)
void be_tls_get_peer_issuer_name(Port *port, char *ptr, size_t len)
void CreateSharedBackendStatus(void)
LocalPgBackendStatus * pgstat_fetch_stat_local_beentry(int beid)
char * application_name
Definition: guc.c:621
void be_tls_get_peer_subject_name(Port *port, char *ptr, size_t len)
#define pgstat_begin_read_activity(beentry, before_changecount)
void * gss
Definition: libpq-be.h:203
#define PGSTAT_END_WRITE_ACTIVITY(beentry)
void pgstat_report_activity(BackendState state, const char *cmd_str)
#define unvolatize(underlying_type, expr)
Definition: c.h:1245
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:863
void be_tls_get_peer_serial(Port *port, char *ptr, size_t len)
TimestampTz st_xact_start_timestamp
int i
void * arg
static void pgstat_read_current_status(void)
const char * be_tls_get_cipher(Port *port)
#define pgstat_read_activity_complete(before_changecount, after_changecount)
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:120
void TimestampDifference(TimestampTz start_time, TimestampTz stop_time, long *secs, int *microsecs)
Definition: timestamp.c:1656
Definition: proc.h:121
bool pgstat_track_activities
TimestampTz st_proc_start_timestamp
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static char * BackendClientHostnameBuffer
void pgstat_clear_backend_activity_snapshot(void)
PgBackendGSSStatus * st_gssstatus
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Definition: xact.c:807
#define NumBackendStatSlots