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bgworker.c
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1 /*--------------------------------------------------------------------
2  * bgworker.c
3  * POSTGRES pluggable background workers implementation
4  *
5  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
6  *
7  * IDENTIFICATION
8  * src/backend/postmaster/bgworker.c
9  *
10  *-------------------------------------------------------------------------
11  */
12 
13 #include "postgres.h"
14 
15 #include "access/parallel.h"
16 #include "libpq/pqsignal.h"
17 #include "miscadmin.h"
18 #include "pgstat.h"
19 #include "port/atomics.h"
21 #include "postmaster/postmaster.h"
24 #include "storage/ipc.h"
25 #include "storage/latch.h"
26 #include "storage/lwlock.h"
27 #include "storage/pmsignal.h"
28 #include "storage/proc.h"
29 #include "storage/procsignal.h"
30 #include "storage/shmem.h"
31 #include "tcop/tcopprot.h"
32 #include "utils/ascii.h"
33 #include "utils/memutils.h"
34 #include "utils/ps_status.h"
35 #include "utils/timeout.h"
36 
37 /*
38  * The postmaster's list of registered background workers, in private memory.
39  */
41 
42 /*
43  * BackgroundWorkerSlots exist in shared memory and can be accessed (via
44  * the BackgroundWorkerArray) by both the postmaster and by regular backends.
45  * However, the postmaster cannot take locks, even spinlocks, because this
46  * might allow it to crash or become wedged if shared memory gets corrupted.
47  * Such an outcome is intolerable. Therefore, we need a lockless protocol
48  * for coordinating access to this data.
49  *
50  * The 'in_use' flag is used to hand off responsibility for the slot between
51  * the postmaster and the rest of the system. When 'in_use' is false,
52  * the postmaster will ignore the slot entirely, except for the 'in_use' flag
53  * itself, which it may read. In this state, regular backends may modify the
54  * slot. Once a backend sets 'in_use' to true, the slot becomes the
55  * responsibility of the postmaster. Regular backends may no longer modify it,
56  * but the postmaster may examine it. Thus, a backend initializing a slot
57  * must fully initialize the slot - and insert a write memory barrier - before
58  * marking it as in use.
59  *
60  * As an exception, however, even when the slot is in use, regular backends
61  * may set the 'terminate' flag for a slot, telling the postmaster not
62  * to restart it. Once the background worker is no longer running, the slot
63  * will be released for reuse.
64  *
65  * In addition to coordinating with the postmaster, backends modifying this
66  * data structure must coordinate with each other. Since they can take locks,
67  * this is straightforward: any backend wishing to manipulate a slot must
68  * take BackgroundWorkerLock in exclusive mode. Backends wishing to read
69  * data that might get concurrently modified by other backends should take
70  * this lock in shared mode. No matter what, backends reading this data
71  * structure must be able to tolerate concurrent modifications by the
72  * postmaster.
73  */
74 typedef struct BackgroundWorkerSlot
75 {
76  bool in_use;
77  bool terminate;
78  pid_t pid; /* InvalidPid = not started yet; 0 = dead */
79  uint64 generation; /* incremented when slot is recycled */
82 
83 /*
84  * In order to limit the total number of parallel workers (according to
85  * max_parallel_workers GUC), we maintain the number of active parallel
86  * workers. Since the postmaster cannot take locks, two variables are used for
87  * this purpose: the number of registered parallel workers (modified by the
88  * backends, protected by BackgroundWorkerLock) and the number of terminated
89  * parallel workers (modified only by the postmaster, lockless). The active
90  * number of parallel workers is the number of registered workers minus the
91  * terminated ones. These counters can of course overflow, but it's not
92  * important here since the subtraction will still give the right number.
93  */
94 typedef struct BackgroundWorkerArray
95 {
101 
103 {
104  int slot;
105  uint64 generation;
106 };
107 
109 
110 /*
111  * List of internal background worker entry points. We need this for
112  * reasons explained in LookupBackgroundWorkerFunction(), below.
113  */
114 static const struct
115 {
116  const char *fn_name;
118 } InternalBGWorkers[] =
119 
120 {
121  {
122  "ParallelWorkerMain", ParallelWorkerMain
123  },
124  {
125  "ApplyLauncherMain", ApplyLauncherMain
126  },
127  {
128  "ApplyWorkerMain", ApplyWorkerMain
129  },
130  {
131  "ParallelApplyWorkerMain", ParallelApplyWorkerMain
132  },
133  {
134  "TablesyncWorkerMain", TablesyncWorkerMain
135  }
136 };
137 
138 /* Private functions. */
139 static bgworker_main_type LookupBackgroundWorkerFunction(const char *libraryname, const char *funcname);
140 
141 
142 /*
143  * Calculate shared memory needed.
144  */
145 Size
147 {
148  Size size;
149 
150  /* Array of workers is variably sized. */
151  size = offsetof(BackgroundWorkerArray, slot);
153  sizeof(BackgroundWorkerSlot)));
154 
155  return size;
156 }
157 
158 /*
159  * Initialize shared memory.
160  */
161 void
163 {
164  bool found;
165 
166  BackgroundWorkerData = ShmemInitStruct("Background Worker Data",
168  &found);
169  if (!IsUnderPostmaster)
170  {
171  slist_iter siter;
172  int slotno = 0;
173 
177 
178  /*
179  * Copy contents of worker list into shared memory. Record the shared
180  * memory slot assigned to each worker. This ensures a 1-to-1
181  * correspondence between the postmaster's private list and the array
182  * in shared memory.
183  */
185  {
187  RegisteredBgWorker *rw;
188 
189  rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
190  Assert(slotno < max_worker_processes);
191  slot->in_use = true;
192  slot->terminate = false;
193  slot->pid = InvalidPid;
194  slot->generation = 0;
195  rw->rw_shmem_slot = slotno;
196  rw->rw_worker.bgw_notify_pid = 0; /* might be reinit after crash */
197  memcpy(&slot->worker, &rw->rw_worker, sizeof(BackgroundWorker));
198  ++slotno;
199  }
200 
201  /*
202  * Mark any remaining slots as not in use.
203  */
204  while (slotno < max_worker_processes)
205  {
207 
208  slot->in_use = false;
209  ++slotno;
210  }
211  }
212  else
213  Assert(found);
214 }
215 
216 /*
217  * Search the postmaster's backend-private list of RegisteredBgWorker objects
218  * for the one that maps to the given slot number.
219  */
220 static RegisteredBgWorker *
222 {
223  slist_iter siter;
224 
226  {
227  RegisteredBgWorker *rw;
228 
229  rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
230  if (rw->rw_shmem_slot == slotno)
231  return rw;
232  }
233 
234  return NULL;
235 }
236 
237 /*
238  * Notice changes to shared memory made by other backends.
239  * Accept new worker requests only if allow_new_workers is true.
240  *
241  * This code runs in the postmaster, so we must be very careful not to assume
242  * that shared memory contents are sane. Otherwise, a rogue backend could
243  * take out the postmaster.
244  */
245 void
246 BackgroundWorkerStateChange(bool allow_new_workers)
247 {
248  int slotno;
249 
250  /*
251  * The total number of slots stored in shared memory should match our
252  * notion of max_worker_processes. If it does not, something is very
253  * wrong. Further down, we always refer to this value as
254  * max_worker_processes, in case shared memory gets corrupted while we're
255  * looping.
256  */
258  {
259  ereport(LOG,
260  (errmsg("inconsistent background worker state (max_worker_processes=%d, total_slots=%d)",
263  return;
264  }
265 
266  /*
267  * Iterate through slots, looking for newly-registered workers or workers
268  * who must die.
269  */
270  for (slotno = 0; slotno < max_worker_processes; ++slotno)
271  {
273  RegisteredBgWorker *rw;
274 
275  if (!slot->in_use)
276  continue;
277 
278  /*
279  * Make sure we don't see the in_use flag before the updated slot
280  * contents.
281  */
282  pg_read_barrier();
283 
284  /* See whether we already know about this worker. */
286  if (rw != NULL)
287  {
288  /*
289  * In general, the worker data can't change after it's initially
290  * registered. However, someone can set the terminate flag.
291  */
292  if (slot->terminate && !rw->rw_terminate)
293  {
294  rw->rw_terminate = true;
295  if (rw->rw_pid != 0)
296  kill(rw->rw_pid, SIGTERM);
297  else
298  {
299  /* Report never-started, now-terminated worker as dead. */
301  }
302  }
303  continue;
304  }
305 
306  /*
307  * If we aren't allowing new workers, then immediately mark it for
308  * termination; the next stanza will take care of cleaning it up.
309  * Doing this ensures that any process waiting for the worker will get
310  * awoken, even though the worker will never be allowed to run.
311  */
312  if (!allow_new_workers)
313  slot->terminate = true;
314 
315  /*
316  * If the worker is marked for termination, we don't need to add it to
317  * the registered workers list; we can just free the slot. However, if
318  * bgw_notify_pid is set, the process that registered the worker may
319  * need to know that we've processed the terminate request, so be sure
320  * to signal it.
321  */
322  if (slot->terminate)
323  {
324  int notify_pid;
325 
326  /*
327  * We need a memory barrier here to make sure that the load of
328  * bgw_notify_pid and the update of parallel_terminate_count
329  * complete before the store to in_use.
330  */
331  notify_pid = slot->worker.bgw_notify_pid;
332  if ((slot->worker.bgw_flags & BGWORKER_CLASS_PARALLEL) != 0)
334  slot->pid = 0;
335 
337  slot->in_use = false;
338 
339  if (notify_pid != 0)
340  kill(notify_pid, SIGUSR1);
341 
342  continue;
343  }
344 
345  /*
346  * Copy the registration data into the registered workers list.
347  */
349  sizeof(RegisteredBgWorker),
351  if (rw == NULL)
352  {
353  ereport(LOG,
354  (errcode(ERRCODE_OUT_OF_MEMORY),
355  errmsg("out of memory")));
356  return;
357  }
358 
359  /*
360  * Copy strings in a paranoid way. If shared memory is corrupted, the
361  * source data might not even be NUL-terminated.
362  */
364  slot->worker.bgw_name, BGW_MAXLEN);
366  slot->worker.bgw_type, BGW_MAXLEN);
371 
372  /*
373  * Copy various fixed-size fields.
374  *
375  * flags, start_time, and restart_time are examined by the postmaster,
376  * but nothing too bad will happen if they are corrupted. The
377  * remaining fields will only be examined by the child process. It
378  * might crash, but we won't.
379  */
380  rw->rw_worker.bgw_flags = slot->worker.bgw_flags;
384  memcpy(rw->rw_worker.bgw_extra, slot->worker.bgw_extra, BGW_EXTRALEN);
385 
386  /*
387  * Copy the PID to be notified about state changes, but only if the
388  * postmaster knows about a backend with that PID. It isn't an error
389  * if the postmaster doesn't know about the PID, because the backend
390  * that requested the worker could have died (or been killed) just
391  * after doing so. Nonetheless, at least until we get some experience
392  * with how this plays out in the wild, log a message at a relative
393  * high debug level.
394  */
397  {
398  elog(DEBUG1, "worker notification PID %d is not valid",
399  (int) rw->rw_worker.bgw_notify_pid);
400  rw->rw_worker.bgw_notify_pid = 0;
401  }
402 
403  /* Initialize postmaster bookkeeping. */
404  rw->rw_backend = NULL;
405  rw->rw_pid = 0;
406  rw->rw_child_slot = 0;
407  rw->rw_crashed_at = 0;
408  rw->rw_shmem_slot = slotno;
409  rw->rw_terminate = false;
410 
411  /* Log it! */
412  ereport(DEBUG1,
413  (errmsg_internal("registering background worker \"%s\"",
414  rw->rw_worker.bgw_name)));
415 
417  }
418 }
419 
420 /*
421  * Forget about a background worker that's no longer needed.
422  *
423  * The worker must be identified by passing an slist_mutable_iter that
424  * points to it. This convention allows deletion of workers during
425  * searches of the worker list, and saves having to search the list again.
426  *
427  * Caller is responsible for notifying bgw_notify_pid, if appropriate.
428  *
429  * This function must be invoked only in the postmaster.
430  */
431 void
433 {
434  RegisteredBgWorker *rw;
435  BackgroundWorkerSlot *slot;
436 
437  rw = slist_container(RegisteredBgWorker, rw_lnode, cur->cur);
438 
441  Assert(slot->in_use);
442 
443  /*
444  * We need a memory barrier here to make sure that the update of
445  * parallel_terminate_count completes before the store to in_use.
446  */
449 
451  slot->in_use = false;
452 
453  ereport(DEBUG1,
454  (errmsg_internal("unregistering background worker \"%s\"",
455  rw->rw_worker.bgw_name)));
456 
458  pfree(rw);
459 }
460 
461 /*
462  * Report the PID of a newly-launched background worker in shared memory.
463  *
464  * This function should only be called from the postmaster.
465  */
466 void
468 {
469  BackgroundWorkerSlot *slot;
470 
473  slot->pid = rw->rw_pid;
474 
475  if (rw->rw_worker.bgw_notify_pid != 0)
477 }
478 
479 /*
480  * Report that the PID of a background worker is now zero because a
481  * previously-running background worker has exited.
482  *
483  * This function should only be called from the postmaster.
484  */
485 void
487 {
488  RegisteredBgWorker *rw;
489  BackgroundWorkerSlot *slot;
490  int notify_pid;
491 
492  rw = slist_container(RegisteredBgWorker, rw_lnode, cur->cur);
493 
496  slot->pid = rw->rw_pid;
497  notify_pid = rw->rw_worker.bgw_notify_pid;
498 
499  /*
500  * If this worker is slated for deregistration, do that before notifying
501  * the process which started it. Otherwise, if that process tries to
502  * reuse the slot immediately, it might not be available yet. In theory
503  * that could happen anyway if the process checks slot->pid at just the
504  * wrong moment, but this makes the window narrower.
505  */
506  if (rw->rw_terminate ||
509 
510  if (notify_pid != 0)
511  kill(notify_pid, SIGUSR1);
512 }
513 
514 /*
515  * Cancel SIGUSR1 notifications for a PID belonging to an exiting backend.
516  *
517  * This function should only be called from the postmaster.
518  */
519 void
521 {
522  slist_iter siter;
523 
525  {
526  RegisteredBgWorker *rw;
527 
528  rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
529  if (rw->rw_worker.bgw_notify_pid == pid)
530  rw->rw_worker.bgw_notify_pid = 0;
531  }
532 }
533 
534 /*
535  * Cancel any not-yet-started worker requests that have waiting processes.
536  *
537  * This is called during a normal ("smart" or "fast") database shutdown.
538  * After this point, no new background workers will be started, so anything
539  * that might be waiting for them needs to be kicked off its wait. We do
540  * that by canceling the bgworker registration entirely, which is perhaps
541  * overkill, but since we're shutting down it does not matter whether the
542  * registration record sticks around.
543  *
544  * This function should only be called from the postmaster.
545  */
546 void
548 {
549  slist_mutable_iter iter;
550 
552  {
553  RegisteredBgWorker *rw;
554  BackgroundWorkerSlot *slot;
555 
556  rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
559 
560  /* If it's not yet started, and there's someone waiting ... */
561  if (slot->pid == InvalidPid &&
562  rw->rw_worker.bgw_notify_pid != 0)
563  {
564  /* ... then zap it, and notify the waiter */
565  int notify_pid = rw->rw_worker.bgw_notify_pid;
566 
567  ForgetBackgroundWorker(&iter);
568  if (notify_pid != 0)
569  kill(notify_pid, SIGUSR1);
570  }
571  }
572 }
573 
574 /*
575  * Reset background worker crash state.
576  *
577  * We assume that, after a crash-and-restart cycle, background workers without
578  * the never-restart flag should be restarted immediately, instead of waiting
579  * for bgw_restart_time to elapse. On the other hand, workers with that flag
580  * should be forgotten immediately, since we won't ever restart them.
581  *
582  * This function should only be called from the postmaster.
583  */
584 void
586 {
587  slist_mutable_iter iter;
588 
590  {
591  RegisteredBgWorker *rw;
592 
593  rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
594 
596  {
597  /*
598  * Workers marked BGW_NEVER_RESTART shouldn't get relaunched after
599  * the crash, so forget about them. (If we wait until after the
600  * crash to forget about them, and they are parallel workers,
601  * parallel_terminate_count will get incremented after we've
602  * already zeroed parallel_register_count, which would be bad.)
603  */
604  ForgetBackgroundWorker(&iter);
605  }
606  else
607  {
608  /*
609  * The accounting which we do via parallel_register_count and
610  * parallel_terminate_count would get messed up if a worker marked
611  * parallel could survive a crash and restart cycle. All such
612  * workers should be marked BGW_NEVER_RESTART, and thus control
613  * should never reach this branch.
614  */
616 
617  /*
618  * Allow this worker to be restarted immediately after we finish
619  * resetting.
620  */
621  rw->rw_crashed_at = 0;
622 
623  /*
624  * If there was anyone waiting for it, they're history.
625  */
626  rw->rw_worker.bgw_notify_pid = 0;
627  }
628  }
629 }
630 
631 /*
632  * Complain about the BackgroundWorker definition using error level elevel.
633  * Return true if it looks ok, false if not (unless elevel >= ERROR, in
634  * which case we won't return at all in the not-OK case).
635  */
636 static bool
638 {
639  /* sanity check for flags */
640 
641  /*
642  * We used to support workers not connected to shared memory, but don't
643  * anymore. Thus this is a required flag now. We're not removing the flag
644  * for compatibility reasons and because the flag still provides some
645  * signal when reading code.
646  */
647  if (!(worker->bgw_flags & BGWORKER_SHMEM_ACCESS))
648  {
649  ereport(elevel,
650  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
651  errmsg("background worker \"%s\": background workers without shared memory access are not supported",
652  worker->bgw_name)));
653  return false;
654  }
655 
657  {
659  {
660  ereport(elevel,
661  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
662  errmsg("background worker \"%s\": cannot request database access if starting at postmaster start",
663  worker->bgw_name)));
664  return false;
665  }
666 
667  /* XXX other checks? */
668  }
669 
670  if ((worker->bgw_restart_time < 0 &&
671  worker->bgw_restart_time != BGW_NEVER_RESTART) ||
672  (worker->bgw_restart_time > USECS_PER_DAY / 1000))
673  {
674  ereport(elevel,
675  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
676  errmsg("background worker \"%s\": invalid restart interval",
677  worker->bgw_name)));
678  return false;
679  }
680 
681  /*
682  * Parallel workers may not be configured for restart, because the
683  * parallel_register_count/parallel_terminate_count accounting can't
684  * handle parallel workers lasting through a crash-and-restart cycle.
685  */
686  if (worker->bgw_restart_time != BGW_NEVER_RESTART &&
687  (worker->bgw_flags & BGWORKER_CLASS_PARALLEL) != 0)
688  {
689  ereport(elevel,
690  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
691  errmsg("background worker \"%s\": parallel workers may not be configured for restart",
692  worker->bgw_name)));
693  return false;
694  }
695 
696  /*
697  * If bgw_type is not filled in, use bgw_name.
698  */
699  if (strcmp(worker->bgw_type, "") == 0)
700  strcpy(worker->bgw_type, worker->bgw_name);
701 
702  return true;
703 }
704 
705 /*
706  * Standard SIGTERM handler for background workers
707  */
708 static void
710 {
711  sigprocmask(SIG_SETMASK, &BlockSig, NULL);
712 
713  ereport(FATAL,
714  (errcode(ERRCODE_ADMIN_SHUTDOWN),
715  errmsg("terminating background worker \"%s\" due to administrator command",
717 }
718 
719 /*
720  * Main entry point for background worker processes.
721  */
722 void
723 BackgroundWorkerMain(char *startup_data, size_t startup_data_len)
724 {
725  sigjmp_buf local_sigjmp_buf;
726  BackgroundWorker *worker;
727  bgworker_main_type entrypt;
728 
729  if (startup_data == NULL)
730  elog(FATAL, "unable to find bgworker entry");
731  Assert(startup_data_len == sizeof(BackgroundWorker));
733  memcpy(worker, startup_data, sizeof(BackgroundWorker));
734 
735  /*
736  * Now that we're done reading the startup data, release postmaster's
737  * working memory context.
738  */
739  if (PostmasterContext)
740  {
742  PostmasterContext = NULL;
743  }
744 
745  MyBgworkerEntry = worker;
747  init_ps_display(worker->bgw_name);
748 
750 
751  /* Apply PostAuthDelay */
752  if (PostAuthDelay > 0)
753  pg_usleep(PostAuthDelay * 1000000L);
754 
755  /*
756  * Set up signal handlers.
757  */
759  {
760  /*
761  * SIGINT is used to signal canceling the current action
762  */
766 
767  /* XXX Any other handlers needed here? */
768  }
769  else
770  {
771  pqsignal(SIGINT, SIG_IGN);
773  pqsignal(SIGFPE, SIG_IGN);
774  }
775  pqsignal(SIGTERM, bgworker_die);
776  /* SIGQUIT handler was already set up by InitPostmasterChild */
778 
779  InitializeTimeouts(); /* establishes SIGALRM handler */
780 
784 
785  /*
786  * If an exception is encountered, processing resumes here.
787  *
788  * We just need to clean up, report the error, and go away.
789  */
790  if (sigsetjmp(local_sigjmp_buf, 1) != 0)
791  {
792  /* Since not using PG_TRY, must reset error stack by hand */
793  error_context_stack = NULL;
794 
795  /* Prevent interrupts while cleaning up */
796  HOLD_INTERRUPTS();
797 
798  /*
799  * sigsetjmp will have blocked all signals, but we may need to accept
800  * signals while communicating with our parallel leader. Once we've
801  * done HOLD_INTERRUPTS() it should be safe to unblock signals.
802  */
804 
805  /* Report the error to the parallel leader and the server log */
806  EmitErrorReport();
807 
808  /*
809  * Do we need more cleanup here? For shmem-connected bgworkers, we
810  * will call InitProcess below, which will install ProcKill as exit
811  * callback. That will take care of releasing locks, etc.
812  */
813 
814  /* and go away */
815  proc_exit(1);
816  }
817 
818  /* We can now handle ereport(ERROR) */
819  PG_exception_stack = &local_sigjmp_buf;
820 
821  /*
822  * Create a per-backend PGPROC struct in shared memory. We must do this
823  * before we can use LWLocks or access any shared memory.
824  */
825  InitProcess();
826 
827  /*
828  * Early initialization.
829  */
830  BaseInit();
831 
832  /*
833  * Look up the entry point function, loading its library if necessary.
834  */
836  worker->bgw_function_name);
837 
838  /*
839  * Note that in normal processes, we would call InitPostgres here. For a
840  * worker, however, we don't know what database to connect to, yet; so we
841  * need to wait until the user code does it via
842  * BackgroundWorkerInitializeConnection().
843  */
844 
845  /*
846  * Now invoke the user-defined worker code
847  */
848  entrypt(worker->bgw_main_arg);
849 
850  /* ... and if it returns, we're done */
851  proc_exit(0);
852 }
853 
854 /*
855  * Register a new static background worker.
856  *
857  * This can only be called directly from postmaster or in the _PG_init
858  * function of a module library that's loaded by shared_preload_libraries;
859  * otherwise it will have no effect.
860  */
861 void
863 {
864  RegisteredBgWorker *rw;
865  static int numworkers = 0;
866 
867  /*
868  * Static background workers can only be registered in the postmaster
869  * process.
870  */
872  {
873  /*
874  * In EXEC_BACKEND or single-user mode, we process
875  * shared_preload_libraries in backend processes too. We cannot
876  * register static background workers at that stage, but many
877  * libraries' _PG_init() functions don't distinguish whether they're
878  * being loaded in the postmaster or in a backend, they just check
879  * process_shared_preload_libraries_in_progress. It's a bit sloppy,
880  * but for historical reasons we tolerate it. In EXEC_BACKEND mode,
881  * the background workers should already have been registered when the
882  * library was loaded in postmaster.
883  */
885  return;
886  ereport(LOG,
887  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
888  errmsg("background worker \"%s\": must be registered in \"shared_preload_libraries\"",
889  worker->bgw_name)));
890  return;
891  }
892 
893  /*
894  * Cannot register static background workers after calling
895  * BackgroundWorkerShmemInit().
896  */
897  if (BackgroundWorkerData != NULL)
898  elog(ERROR, "cannot register background worker \"%s\" after shmem init",
899  worker->bgw_name);
900 
901  ereport(DEBUG1,
902  (errmsg_internal("registering background worker \"%s\"", worker->bgw_name)));
903 
904  if (!SanityCheckBackgroundWorker(worker, LOG))
905  return;
906 
907  if (worker->bgw_notify_pid != 0)
908  {
909  ereport(LOG,
910  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
911  errmsg("background worker \"%s\": only dynamic background workers can request notification",
912  worker->bgw_name)));
913  return;
914  }
915 
916  /*
917  * Enforce maximum number of workers. Note this is overly restrictive: we
918  * could allow more non-shmem-connected workers, because these don't count
919  * towards the MAX_BACKENDS limit elsewhere. For now, it doesn't seem
920  * important to relax this restriction.
921  */
922  if (++numworkers > max_worker_processes)
923  {
924  ereport(LOG,
925  (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
926  errmsg("too many background workers"),
927  errdetail_plural("Up to %d background worker can be registered with the current settings.",
928  "Up to %d background workers can be registered with the current settings.",
931  errhint("Consider increasing the configuration parameter \"max_worker_processes\".")));
932  return;
933  }
934 
935  /*
936  * Copy the registration data into the registered workers list.
937  */
939  sizeof(RegisteredBgWorker),
941  if (rw == NULL)
942  {
943  ereport(LOG,
944  (errcode(ERRCODE_OUT_OF_MEMORY),
945  errmsg("out of memory")));
946  return;
947  }
948 
949  rw->rw_worker = *worker;
950  rw->rw_backend = NULL;
951  rw->rw_pid = 0;
952  rw->rw_child_slot = 0;
953  rw->rw_crashed_at = 0;
954  rw->rw_terminate = false;
955 
957 }
958 
959 /*
960  * Register a new background worker from a regular backend.
961  *
962  * Returns true on success and false on failure. Failure typically indicates
963  * that no background worker slots are currently available.
964  *
965  * If handle != NULL, we'll set *handle to a pointer that can subsequently
966  * be used as an argument to GetBackgroundWorkerPid(). The caller can
967  * free this pointer using pfree(), if desired.
968  */
969 bool
971  BackgroundWorkerHandle **handle)
972 {
973  int slotno;
974  bool success = false;
975  bool parallel;
976  uint64 generation = 0;
977 
978  /*
979  * We can't register dynamic background workers from the postmaster. If
980  * this is a standalone backend, we're the only process and can't start
981  * any more. In a multi-process environment, it might be theoretically
982  * possible, but we don't currently support it due to locking
983  * considerations; see comments on the BackgroundWorkerSlot data
984  * structure.
985  */
986  if (!IsUnderPostmaster)
987  return false;
988 
989  if (!SanityCheckBackgroundWorker(worker, ERROR))
990  return false;
991 
992  parallel = (worker->bgw_flags & BGWORKER_CLASS_PARALLEL) != 0;
993 
994  LWLockAcquire(BackgroundWorkerLock, LW_EXCLUSIVE);
995 
996  /*
997  * If this is a parallel worker, check whether there are already too many
998  * parallel workers; if so, don't register another one. Our view of
999  * parallel_terminate_count may be slightly stale, but that doesn't really
1000  * matter: we would have gotten the same result if we'd arrived here
1001  * slightly earlier anyway. There's no help for it, either, since the
1002  * postmaster must not take locks; a memory barrier wouldn't guarantee
1003  * anything useful.
1004  */
1005  if (parallel && (BackgroundWorkerData->parallel_register_count -
1008  {
1012  LWLockRelease(BackgroundWorkerLock);
1013  return false;
1014  }
1015 
1016  /*
1017  * Look for an unused slot. If we find one, grab it.
1018  */
1019  for (slotno = 0; slotno < BackgroundWorkerData->total_slots; ++slotno)
1020  {
1022 
1023  if (!slot->in_use)
1024  {
1025  memcpy(&slot->worker, worker, sizeof(BackgroundWorker));
1026  slot->pid = InvalidPid; /* indicates not started yet */
1027  slot->generation++;
1028  slot->terminate = false;
1029  generation = slot->generation;
1030  if (parallel)
1032 
1033  /*
1034  * Make sure postmaster doesn't see the slot as in use before it
1035  * sees the new contents.
1036  */
1037  pg_write_barrier();
1038 
1039  slot->in_use = true;
1040  success = true;
1041  break;
1042  }
1043  }
1044 
1045  LWLockRelease(BackgroundWorkerLock);
1046 
1047  /* If we found a slot, tell the postmaster to notice the change. */
1048  if (success)
1050 
1051  /*
1052  * If we found a slot and the user has provided a handle, initialize it.
1053  */
1054  if (success && handle)
1055  {
1056  *handle = palloc(sizeof(BackgroundWorkerHandle));
1057  (*handle)->slot = slotno;
1058  (*handle)->generation = generation;
1059  }
1060 
1061  return success;
1062 }
1063 
1064 /*
1065  * Get the PID of a dynamically-registered background worker.
1066  *
1067  * If the worker is determined to be running, the return value will be
1068  * BGWH_STARTED and *pidp will get the PID of the worker process. If the
1069  * postmaster has not yet attempted to start the worker, the return value will
1070  * be BGWH_NOT_YET_STARTED. Otherwise, the return value is BGWH_STOPPED.
1071  *
1072  * BGWH_STOPPED can indicate either that the worker is temporarily stopped
1073  * (because it is configured for automatic restart and exited non-zero),
1074  * or that the worker is permanently stopped (because it exited with exit
1075  * code 0, or was not configured for automatic restart), or even that the
1076  * worker was unregistered without ever starting (either because startup
1077  * failed and the worker is not configured for automatic restart, or because
1078  * TerminateBackgroundWorker was used before the worker was successfully
1079  * started).
1080  */
1083 {
1084  BackgroundWorkerSlot *slot;
1085  pid_t pid;
1086 
1087  Assert(handle->slot < max_worker_processes);
1088  slot = &BackgroundWorkerData->slot[handle->slot];
1089 
1090  /*
1091  * We could probably arrange to synchronize access to data using memory
1092  * barriers only, but for now, let's just keep it simple and grab the
1093  * lock. It seems unlikely that there will be enough traffic here to
1094  * result in meaningful contention.
1095  */
1096  LWLockAcquire(BackgroundWorkerLock, LW_SHARED);
1097 
1098  /*
1099  * The generation number can't be concurrently changed while we hold the
1100  * lock. The pid, which is updated by the postmaster, can change at any
1101  * time, but we assume such changes are atomic. So the value we read
1102  * won't be garbage, but it might be out of date by the time the caller
1103  * examines it (but that's unavoidable anyway).
1104  *
1105  * The in_use flag could be in the process of changing from true to false,
1106  * but if it is already false then it can't change further.
1107  */
1108  if (handle->generation != slot->generation || !slot->in_use)
1109  pid = 0;
1110  else
1111  pid = slot->pid;
1112 
1113  /* All done. */
1114  LWLockRelease(BackgroundWorkerLock);
1115 
1116  if (pid == 0)
1117  return BGWH_STOPPED;
1118  else if (pid == InvalidPid)
1119  return BGWH_NOT_YET_STARTED;
1120  *pidp = pid;
1121  return BGWH_STARTED;
1122 }
1123 
1124 /*
1125  * Wait for a background worker to start up.
1126  *
1127  * This is like GetBackgroundWorkerPid(), except that if the worker has not
1128  * yet started, we wait for it to do so; thus, BGWH_NOT_YET_STARTED is never
1129  * returned. However, if the postmaster has died, we give up and return
1130  * BGWH_POSTMASTER_DIED, since it that case we know that startup will not
1131  * take place.
1132  *
1133  * The caller *must* have set our PID as the worker's bgw_notify_pid,
1134  * else we will not be awoken promptly when the worker's state changes.
1135  */
1138 {
1139  BgwHandleStatus status;
1140  int rc;
1141 
1142  for (;;)
1143  {
1144  pid_t pid;
1145 
1147 
1148  status = GetBackgroundWorkerPid(handle, &pid);
1149  if (status == BGWH_STARTED)
1150  *pidp = pid;
1151  if (status != BGWH_NOT_YET_STARTED)
1152  break;
1153 
1154  rc = WaitLatch(MyLatch,
1156  WAIT_EVENT_BGWORKER_STARTUP);
1157 
1158  if (rc & WL_POSTMASTER_DEATH)
1159  {
1160  status = BGWH_POSTMASTER_DIED;
1161  break;
1162  }
1163 
1165  }
1166 
1167  return status;
1168 }
1169 
1170 /*
1171  * Wait for a background worker to stop.
1172  *
1173  * If the worker hasn't yet started, or is running, we wait for it to stop
1174  * and then return BGWH_STOPPED. However, if the postmaster has died, we give
1175  * up and return BGWH_POSTMASTER_DIED, because it's the postmaster that
1176  * notifies us when a worker's state changes.
1177  *
1178  * The caller *must* have set our PID as the worker's bgw_notify_pid,
1179  * else we will not be awoken promptly when the worker's state changes.
1180  */
1183 {
1184  BgwHandleStatus status;
1185  int rc;
1186 
1187  for (;;)
1188  {
1189  pid_t pid;
1190 
1192 
1193  status = GetBackgroundWorkerPid(handle, &pid);
1194  if (status == BGWH_STOPPED)
1195  break;
1196 
1197  rc = WaitLatch(MyLatch,
1199  WAIT_EVENT_BGWORKER_SHUTDOWN);
1200 
1201  if (rc & WL_POSTMASTER_DEATH)
1202  {
1203  status = BGWH_POSTMASTER_DIED;
1204  break;
1205  }
1206 
1208  }
1209 
1210  return status;
1211 }
1212 
1213 /*
1214  * Instruct the postmaster to terminate a background worker.
1215  *
1216  * Note that it's safe to do this without regard to whether the worker is
1217  * still running, or even if the worker may already have exited and been
1218  * unregistered.
1219  */
1220 void
1222 {
1223  BackgroundWorkerSlot *slot;
1224  bool signal_postmaster = false;
1225 
1226  Assert(handle->slot < max_worker_processes);
1227  slot = &BackgroundWorkerData->slot[handle->slot];
1228 
1229  /* Set terminate flag in shared memory, unless slot has been reused. */
1230  LWLockAcquire(BackgroundWorkerLock, LW_EXCLUSIVE);
1231  if (handle->generation == slot->generation)
1232  {
1233  slot->terminate = true;
1234  signal_postmaster = true;
1235  }
1236  LWLockRelease(BackgroundWorkerLock);
1237 
1238  /* Make sure the postmaster notices the change to shared memory. */
1239  if (signal_postmaster)
1241 }
1242 
1243 /*
1244  * Look up (and possibly load) a bgworker entry point function.
1245  *
1246  * For functions contained in the core code, we use library name "postgres"
1247  * and consult the InternalBGWorkers array. External functions are
1248  * looked up, and loaded if necessary, using load_external_function().
1249  *
1250  * The point of this is to pass function names as strings across process
1251  * boundaries. We can't pass actual function addresses because of the
1252  * possibility that the function has been loaded at a different address
1253  * in a different process. This is obviously a hazard for functions in
1254  * loadable libraries, but it can happen even for functions in the core code
1255  * on platforms using EXEC_BACKEND (e.g., Windows).
1256  *
1257  * At some point it might be worthwhile to get rid of InternalBGWorkers[]
1258  * in favor of applying load_external_function() for core functions too;
1259  * but that raises portability issues that are not worth addressing now.
1260  */
1261 static bgworker_main_type
1262 LookupBackgroundWorkerFunction(const char *libraryname, const char *funcname)
1263 {
1264  /*
1265  * If the function is to be loaded from postgres itself, search the
1266  * InternalBGWorkers array.
1267  */
1268  if (strcmp(libraryname, "postgres") == 0)
1269  {
1270  int i;
1271 
1272  for (i = 0; i < lengthof(InternalBGWorkers); i++)
1273  {
1274  if (strcmp(InternalBGWorkers[i].fn_name, funcname) == 0)
1275  return InternalBGWorkers[i].fn_addr;
1276  }
1277 
1278  /* We can only reach this by programming error. */
1279  elog(ERROR, "internal function \"%s\" not found", funcname);
1280  }
1281 
1282  /* Otherwise load from external library. */
1283  return (bgworker_main_type)
1284  load_external_function(libraryname, funcname, true, NULL);
1285 }
1286 
1287 /*
1288  * Given a PID, get the bgw_type of the background worker. Returns NULL if
1289  * not a valid background worker.
1290  *
1291  * The return value is in static memory belonging to this function, so it has
1292  * to be used before calling this function again. This is so that the caller
1293  * doesn't have to worry about the background worker locking protocol.
1294  */
1295 const char *
1297 {
1298  int slotno;
1299  bool found = false;
1300  static char result[BGW_MAXLEN];
1301 
1302  LWLockAcquire(BackgroundWorkerLock, LW_SHARED);
1303 
1304  for (slotno = 0; slotno < BackgroundWorkerData->total_slots; slotno++)
1305  {
1307 
1308  if (slot->pid > 0 && slot->pid == pid)
1309  {
1310  strcpy(result, slot->worker.bgw_type);
1311  found = true;
1312  break;
1313  }
1314  }
1315 
1316  LWLockRelease(BackgroundWorkerLock);
1317 
1318  if (!found)
1319  return NULL;
1320 
1321  return result;
1322 }
void ParallelApplyWorkerMain(Datum main_arg)
void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz)
Definition: ascii.c:174
#define pg_memory_barrier()
Definition: atomics.h:138
#define pg_read_barrier()
Definition: atomics.h:151
#define pg_write_barrier()
Definition: atomics.h:152
void ParallelWorkerMain(Datum main_arg)
Definition: parallel.c:1271
sigset_t BlockSig
Definition: pqsignal.c:23
void ApplyWorkerMain(Datum main_arg)
Definition: worker.c:4685
void RegisterBackgroundWorker(BackgroundWorker *worker)
Definition: bgworker.c:862
static RegisteredBgWorker * FindRegisteredWorkerBySlotNumber(int slotno)
Definition: bgworker.c:221
BgwHandleStatus WaitForBackgroundWorkerStartup(BackgroundWorkerHandle *handle, pid_t *pidp)
Definition: bgworker.c:1137
static bool SanityCheckBackgroundWorker(BackgroundWorker *worker, int elevel)
Definition: bgworker.c:637
void ReportBackgroundWorkerPID(RegisteredBgWorker *rw)
Definition: bgworker.c:467
void TerminateBackgroundWorker(BackgroundWorkerHandle *handle)
Definition: bgworker.c:1221
static const struct @18 InternalBGWorkers[]
BgwHandleStatus WaitForBackgroundWorkerShutdown(BackgroundWorkerHandle *handle)
Definition: bgworker.c:1182
void ResetBackgroundWorkerCrashTimes(void)
Definition: bgworker.c:585
void BackgroundWorkerShmemInit(void)
Definition: bgworker.c:162
struct BackgroundWorkerSlot BackgroundWorkerSlot
const char * GetBackgroundWorkerTypeByPid(pid_t pid)
Definition: bgworker.c:1296
void ForgetBackgroundWorker(slist_mutable_iter *cur)
Definition: bgworker.c:432
slist_head BackgroundWorkerList
Definition: bgworker.c:40
const char * fn_name
Definition: bgworker.c:116
BgwHandleStatus GetBackgroundWorkerPid(BackgroundWorkerHandle *handle, pid_t *pidp)
Definition: bgworker.c:1082
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:108
static bgworker_main_type LookupBackgroundWorkerFunction(const char *libraryname, const char *funcname)
Definition: bgworker.c:1262
static void bgworker_die(SIGNAL_ARGS)
Definition: bgworker.c:709
void BackgroundWorkerStopNotifications(pid_t pid)
Definition: bgworker.c:520
Size BackgroundWorkerShmemSize(void)
Definition: bgworker.c:146
void BackgroundWorkerStateChange(bool allow_new_workers)
Definition: bgworker.c:246
void BackgroundWorkerMain(char *startup_data, size_t startup_data_len)
Definition: bgworker.c:723
bool RegisterDynamicBackgroundWorker(BackgroundWorker *worker, BackgroundWorkerHandle **handle)
Definition: bgworker.c:970
void ReportBackgroundWorkerExit(slist_mutable_iter *cur)
Definition: bgworker.c:486
bgworker_main_type fn_addr
Definition: bgworker.c:117
void ForgetUnstartedBackgroundWorkers(void)
Definition: bgworker.c:547
struct BackgroundWorkerArray BackgroundWorkerArray
#define BGW_NEVER_RESTART
Definition: bgworker.h:85
#define BGW_EXTRALEN
Definition: bgworker.h:87
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:68
BgwHandleStatus
Definition: bgworker.h:104
@ BGWH_POSTMASTER_DIED
Definition: bgworker.h:108
@ BGWH_STARTED
Definition: bgworker.h:105
@ BGWH_NOT_YET_STARTED
Definition: bgworker.h:106
@ BGWH_STOPPED
Definition: bgworker.h:107
@ BgWorkerStart_PostmasterStart
Definition: bgworker.h:79
#define BGWORKER_BACKEND_DATABASE_CONNECTION
Definition: bgworker.h:60
#define BGWORKER_SHMEM_ACCESS
Definition: bgworker.h:53
void(* bgworker_main_type)(Datum main_arg)
Definition: bgworker.h:72
#define BGW_MAXLEN
Definition: bgworker.h:86
#define MAX_PARALLEL_WORKER_LIMIT
unsigned int uint32
Definition: c.h:506
#define SIGNAL_ARGS
Definition: c.h:1345
#define Assert(condition)
Definition: c.h:858
#define FLEXIBLE_ARRAY_MEMBER
Definition: c.h:398
#define lengthof(array)
Definition: c.h:788
size_t Size
Definition: c.h:605
#define USECS_PER_DAY
Definition: timestamp.h:131
void * load_external_function(const char *filename, const char *funcname, bool signalNotFound, void **filehandle)
Definition: dfmgr.c:105
struct cursor * cur
Definition: ecpg.c:28
int errmsg_internal(const char *fmt,...)
Definition: elog.c:1157
void EmitErrorReport(void)
Definition: elog.c:1670
ErrorContextCallback * error_context_stack
Definition: elog.c:94
int errdetail_plural(const char *fmt_singular, const char *fmt_plural, unsigned long n,...)
Definition: elog.c:1295
int errhint(const char *fmt,...)
Definition: elog.c:1317
int errcode(int sqlerrcode)
Definition: elog.c:857
int errmsg(const char *fmt,...)
Definition: elog.c:1070
sigjmp_buf * PG_exception_stack
Definition: elog.c:96
#define LOG
Definition: elog.h:31
#define FATAL
Definition: elog.h:41
#define DEBUG1
Definition: elog.h:30
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:224
#define ereport(elevel,...)
Definition: elog.h:149
#define MCXT_ALLOC_ZERO
Definition: fe_memutils.h:18
#define MCXT_ALLOC_NO_OOM
Definition: fe_memutils.h:17
bool IsUnderPostmaster
Definition: globals.c:117
int max_parallel_workers
Definition: globals.c:142
bool IsPostmasterEnvironment
Definition: globals.c:116
struct Latch * MyLatch
Definition: globals.c:60
int max_worker_processes
Definition: globals.c:141
static void slist_delete_current(slist_mutable_iter *iter)
Definition: ilist.h:1084
#define slist_foreach_modify(iter, lhead)
Definition: ilist.h:1148
#define SLIST_STATIC_INIT(name)
Definition: ilist.h:283
static void slist_push_head(slist_head *head, slist_node *node)
Definition: ilist.h:1006
#define slist_container(type, membername, ptr)
Definition: ilist.h:1106
#define slist_foreach(iter, lhead)
Definition: ilist.h:1132
#define funcname
Definition: indent_codes.h:69
static bool success
Definition: initdb.c:186
void proc_exit(int code)
Definition: ipc.c:104
int i
Definition: isn.c:73
void ResetLatch(Latch *latch)
Definition: latch.c:724
int WaitLatch(Latch *latch, int wakeEvents, long timeout, uint32 wait_event_info)
Definition: latch.c:517
#define WL_LATCH_SET
Definition: latch.h:127
#define WL_POSTMASTER_DEATH
Definition: latch.h:131
void ApplyLauncherMain(Datum main_arg)
Definition: launcher.c:1122
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1170
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1783
@ LW_SHARED
Definition: lwlock.h:115
@ LW_EXCLUSIVE
Definition: lwlock.h:114
void pfree(void *pointer)
Definition: mcxt.c:1520
MemoryContext TopMemoryContext
Definition: mcxt.c:149
void * MemoryContextAllocExtended(MemoryContext context, Size size, int flags)
Definition: mcxt.c:1237
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:1180
MemoryContext PostmasterContext
Definition: mcxt.c:151
void MemoryContextDelete(MemoryContext context)
Definition: mcxt.c:454
void * palloc(Size size)
Definition: mcxt.c:1316
@ InitProcessing
Definition: miscadmin.h:448
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:122
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:133
#define SetProcessingMode(mode)
Definition: miscadmin.h:460
@ B_BG_WORKER
Definition: miscadmin.h:341
#define InvalidPid
Definition: miscadmin.h:32
BackendType MyBackendType
Definition: miscinit.c:63
bool process_shared_preload_libraries_in_progress
Definition: miscinit.c:1778
#define MAXPGPATH
void SendPostmasterSignal(PMSignalReason reason)
Definition: pmsignal.c:181
@ PMSIGNAL_BACKGROUND_WORKER_CHANGE
Definition: pmsignal.h:40
pqsigfunc pqsignal(int signo, pqsigfunc func)
int PostAuthDelay
Definition: postgres.c:101
void FloatExceptionHandler(SIGNAL_ARGS)
Definition: postgres.c:3019
void StatementCancelHandler(SIGNAL_ARGS)
Definition: postgres.c:3002
void BaseInit(void)
Definition: postinit.c:645
void BackgroundWorkerUnblockSignals(void)
Definition: postmaster.c:4229
BackgroundWorker * MyBgworkerEntry
Definition: postmaster.c:185
bool PostmasterMarkPIDForWorkerNotify(int pid)
Definition: postmaster.c:4528
void procsignal_sigusr1_handler(SIGNAL_ARGS)
Definition: procsignal.c:635
void init_ps_display(const char *fixed_part)
Definition: ps_status.c:267
Size add_size(Size s1, Size s2)
Definition: shmem.c:493
void * ShmemInitStruct(const char *name, Size size, bool *foundPtr)
Definition: shmem.c:387
Size mul_size(Size s1, Size s2)
Definition: shmem.c:510
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Definition: signal.c:53
static pg_noinline void Size size
Definition: slab.c:607
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Definition: proc.c:296
uint32 parallel_terminate_count
Definition: bgworker.c:98
uint32 parallel_register_count
Definition: bgworker.c:97
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:99
BackgroundWorker worker
Definition: bgworker.c:80
char bgw_function_name[BGW_MAXLEN]
Definition: bgworker.h:97
Datum bgw_main_arg
Definition: bgworker.h:98
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:91
int bgw_restart_time
Definition: bgworker.h:95
char bgw_type[BGW_MAXLEN]
Definition: bgworker.h:92
BgWorkerStartTime bgw_start_time
Definition: bgworker.h:94
char bgw_extra[BGW_EXTRALEN]
Definition: bgworker.h:99
pid_t bgw_notify_pid
Definition: bgworker.h:100
char bgw_library_name[MAXPGPATH]
Definition: bgworker.h:96
struct bkend * rw_backend
BackgroundWorker rw_worker
slist_node * cur
Definition: ilist.h:259
slist_node * cur
Definition: ilist.h:274
void TablesyncWorkerMain(Datum main_arg)
Definition: tablesync.c:1711
void InitializeTimeouts(void)
Definition: timeout.c:470
#define SIGCHLD
Definition: win32_port.h:178
#define SIGHUP
Definition: win32_port.h:168
#define SIG_DFL
Definition: win32_port.h:163
#define SIGPIPE
Definition: win32_port.h:173
#define kill(pid, sig)
Definition: win32_port.h:485
#define SIGUSR1
Definition: win32_port.h:180
#define SIGUSR2
Definition: win32_port.h:181
#define SIG_IGN
Definition: win32_port.h:165