PostgreSQL Source Code  git master
bgworker_internals.h File Reference
#include "datatype/timestamp.h"
#include "lib/ilist.h"
#include "postmaster/bgworker.h"
Include dependency graph for bgworker_internals.h:
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Go to the source code of this file.

Data Structures

struct  RegisteredBgWorker
 

Macros

#define MAX_PARALLEL_WORKER_LIMIT   1024
 

Typedefs

typedef struct RegisteredBgWorker RegisteredBgWorker
 

Functions

Size BackgroundWorkerShmemSize (void)
 
void BackgroundWorkerShmemInit (void)
 
void BackgroundWorkerStateChange (void)
 
void ForgetBackgroundWorker (slist_mutable_iter *cur)
 
void ReportBackgroundWorkerPID (RegisteredBgWorker *)
 
void ReportBackgroundWorkerExit (slist_mutable_iter *cur)
 
void BackgroundWorkerStopNotifications (pid_t pid)
 
void ResetBackgroundWorkerCrashTimes (void)
 
void StartBackgroundWorker (void) pg_attribute_noreturn()
 

Variables

slist_head BackgroundWorkerList
 

Macro Definition Documentation

◆ MAX_PARALLEL_WORKER_LIMIT

#define MAX_PARALLEL_WORKER_LIMIT   1024

Definition at line 24 of file bgworker_internals.h.

Referenced by ExecVacuum(), and RegisterDynamicBackgroundWorker().

Typedef Documentation

◆ RegisteredBgWorker

Function Documentation

◆ BackgroundWorkerShmemInit()

void BackgroundWorkerShmemInit ( void  )

Definition at line 158 of file bgworker.c.

References Assert, BackgroundWorkerShmemSize(), BackgroundWorker::bgw_notify_pid, slist_iter::cur, BackgroundWorkerSlot::generation, BackgroundWorkerSlot::in_use, InvalidPid, IsUnderPostmaster, max_worker_processes, BackgroundWorkerArray::parallel_register_count, BackgroundWorkerArray::parallel_terminate_count, BackgroundWorkerSlot::pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_worker, ShmemInitStruct(), slist_container, slist_foreach, BackgroundWorkerArray::slot, BackgroundWorkerSlot::terminate, BackgroundWorkerArray::total_slots, and BackgroundWorkerSlot::worker.

Referenced by CreateSharedMemoryAndSemaphores().

159 {
160  bool found;
161 
162  BackgroundWorkerData = ShmemInitStruct("Background Worker Data",
164  &found);
165  if (!IsUnderPostmaster)
166  {
167  slist_iter siter;
168  int slotno = 0;
169 
173 
174  /*
175  * Copy contents of worker list into shared memory. Record the shared
176  * memory slot assigned to each worker. This ensures a 1-to-1
177  * correspondence between the postmaster's private list and the array
178  * in shared memory.
179  */
181  {
183  RegisteredBgWorker *rw;
184 
185  rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
186  Assert(slotno < max_worker_processes);
187  slot->in_use = true;
188  slot->terminate = false;
189  slot->pid = InvalidPid;
190  slot->generation = 0;
191  rw->rw_shmem_slot = slotno;
192  rw->rw_worker.bgw_notify_pid = 0; /* might be reinit after crash */
193  memcpy(&slot->worker, &rw->rw_worker, sizeof(BackgroundWorker));
194  ++slotno;
195  }
196 
197  /*
198  * Mark any remaining slots as not in use.
199  */
200  while (slotno < max_worker_processes)
201  {
203 
204  slot->in_use = false;
205  ++slotno;
206  }
207  }
208  else
209  Assert(found);
210 }
slist_node * cur
Definition: ilist.h:226
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
Size BackgroundWorkerShmemSize(void)
Definition: bgworker.c:142
void * ShmemInitStruct(const char *name, Size size, bool *foundPtr)
Definition: shmem.c:392
slist_head BackgroundWorkerList
Definition: bgworker.c:42
uint32 parallel_register_count
Definition: bgworker.c:99
bool IsUnderPostmaster
Definition: globals.c:109
#define slist_container(type, membername, ptr)
Definition: ilist.h:674
#define Assert(condition)
Definition: c.h:738
BackgroundWorker worker
Definition: bgworker.c:82
#define slist_foreach(iter, lhead)
Definition: ilist.h:700
uint32 parallel_terminate_count
Definition: bgworker.c:100
pid_t bgw_notify_pid
Definition: bgworker.h:99
int max_worker_processes
Definition: globals.c:133
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101
#define InvalidPid
Definition: miscadmin.h:32

◆ BackgroundWorkerShmemSize()

Size BackgroundWorkerShmemSize ( void  )

Definition at line 142 of file bgworker.c.

References add_size(), max_worker_processes, mul_size(), and offsetof.

Referenced by BackgroundWorkerShmemInit(), and CreateSharedMemoryAndSemaphores().

143 {
144  Size size;
145 
146  /* Array of workers is variably sized. */
147  size = offsetof(BackgroundWorkerArray, slot);
149  sizeof(BackgroundWorkerSlot)));
150 
151  return size;
152 }
Size mul_size(Size s1, Size s2)
Definition: shmem.c:515
Size add_size(Size s1, Size s2)
Definition: shmem.c:498
size_t Size
Definition: c.h:466
int max_worker_processes
Definition: globals.c:133
#define offsetof(type, field)
Definition: c.h:661

◆ BackgroundWorkerStateChange()

void BackgroundWorkerStateChange ( void  )

Definition at line 240 of file bgworker.c.

References ascii_safe_strlcpy(), BackgroundWorker::bgw_extra, BGW_EXTRALEN, BackgroundWorker::bgw_flags, BackgroundWorker::bgw_function_name, BackgroundWorker::bgw_library_name, BackgroundWorker::bgw_main_arg, BGW_MAXLEN, BackgroundWorker::bgw_name, BackgroundWorker::bgw_notify_pid, BackgroundWorker::bgw_restart_time, BackgroundWorker::bgw_start_time, BackgroundWorker::bgw_type, BGWORKER_CLASS_PARALLEL, DEBUG1, elog, ereport, errcode(), errmsg(), FindRegisteredWorkerBySlotNumber(), BackgroundWorkerSlot::in_use, kill, LOG, malloc, max_worker_processes, BackgroundWorkerArray::parallel_terminate_count, pg_memory_barrier, pg_read_barrier, BackgroundWorkerSlot::pid, PostmasterMarkPIDForWorkerNotify(), ReportBackgroundWorkerPID(), RegisteredBgWorker::rw_backend, RegisteredBgWorker::rw_child_slot, RegisteredBgWorker::rw_crashed_at, RegisteredBgWorker::rw_lnode, RegisteredBgWorker::rw_pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_terminate, RegisteredBgWorker::rw_worker, SIGUSR1, slist_push_head(), BackgroundWorkerArray::slot, BackgroundWorkerSlot::terminate, BackgroundWorkerArray::total_slots, and BackgroundWorkerSlot::worker.

Referenced by sigusr1_handler().

241 {
242  int slotno;
243 
244  /*
245  * The total number of slots stored in shared memory should match our
246  * notion of max_worker_processes. If it does not, something is very
247  * wrong. Further down, we always refer to this value as
248  * max_worker_processes, in case shared memory gets corrupted while we're
249  * looping.
250  */
252  {
253  elog(LOG,
254  "inconsistent background worker state (max_worker_processes=%d, total_slots=%d",
257  return;
258  }
259 
260  /*
261  * Iterate through slots, looking for newly-registered workers or workers
262  * who must die.
263  */
264  for (slotno = 0; slotno < max_worker_processes; ++slotno)
265  {
267  RegisteredBgWorker *rw;
268 
269  if (!slot->in_use)
270  continue;
271 
272  /*
273  * Make sure we don't see the in_use flag before the updated slot
274  * contents.
275  */
276  pg_read_barrier();
277 
278  /* See whether we already know about this worker. */
280  if (rw != NULL)
281  {
282  /*
283  * In general, the worker data can't change after it's initially
284  * registered. However, someone can set the terminate flag.
285  */
286  if (slot->terminate && !rw->rw_terminate)
287  {
288  rw->rw_terminate = true;
289  if (rw->rw_pid != 0)
290  kill(rw->rw_pid, SIGTERM);
291  else
292  {
293  /* Report never-started, now-terminated worker as dead. */
295  }
296  }
297  continue;
298  }
299 
300  /*
301  * If the worker is marked for termination, we don't need to add it to
302  * the registered workers list; we can just free the slot. However, if
303  * bgw_notify_pid is set, the process that registered the worker may
304  * need to know that we've processed the terminate request, so be sure
305  * to signal it.
306  */
307  if (slot->terminate)
308  {
309  int notify_pid;
310 
311  /*
312  * We need a memory barrier here to make sure that the load of
313  * bgw_notify_pid and the update of parallel_terminate_count
314  * complete before the store to in_use.
315  */
316  notify_pid = slot->worker.bgw_notify_pid;
317  if ((slot->worker.bgw_flags & BGWORKER_CLASS_PARALLEL) != 0)
320  slot->pid = 0;
321  slot->in_use = false;
322  if (notify_pid != 0)
323  kill(notify_pid, SIGUSR1);
324 
325  continue;
326  }
327 
328  /*
329  * Copy the registration data into the registered workers list.
330  */
331  rw = malloc(sizeof(RegisteredBgWorker));
332  if (rw == NULL)
333  {
334  ereport(LOG,
335  (errcode(ERRCODE_OUT_OF_MEMORY),
336  errmsg("out of memory")));
337  return;
338  }
339 
340  /*
341  * Copy strings in a paranoid way. If shared memory is corrupted, the
342  * source data might not even be NUL-terminated.
343  */
345  slot->worker.bgw_name, BGW_MAXLEN);
347  slot->worker.bgw_type, BGW_MAXLEN);
352 
353  /*
354  * Copy various fixed-size fields.
355  *
356  * flags, start_time, and restart_time are examined by the postmaster,
357  * but nothing too bad will happen if they are corrupted. The
358  * remaining fields will only be examined by the child process. It
359  * might crash, but we won't.
360  */
361  rw->rw_worker.bgw_flags = slot->worker.bgw_flags;
365  memcpy(rw->rw_worker.bgw_extra, slot->worker.bgw_extra, BGW_EXTRALEN);
366 
367  /*
368  * Copy the PID to be notified about state changes, but only if the
369  * postmaster knows about a backend with that PID. It isn't an error
370  * if the postmaster doesn't know about the PID, because the backend
371  * that requested the worker could have died (or been killed) just
372  * after doing so. Nonetheless, at least until we get some experience
373  * with how this plays out in the wild, log a message at a relative
374  * high debug level.
375  */
378  {
379  elog(DEBUG1, "worker notification PID %lu is not valid",
380  (long) rw->rw_worker.bgw_notify_pid);
381  rw->rw_worker.bgw_notify_pid = 0;
382  }
383 
384  /* Initialize postmaster bookkeeping. */
385  rw->rw_backend = NULL;
386  rw->rw_pid = 0;
387  rw->rw_child_slot = 0;
388  rw->rw_crashed_at = 0;
389  rw->rw_shmem_slot = slotno;
390  rw->rw_terminate = false;
391 
392  /* Log it! */
393  ereport(DEBUG1,
394  (errmsg("registering background worker \"%s\"",
395  rw->rw_worker.bgw_name)));
396 
398  }
399 }
char bgw_extra[BGW_EXTRALEN]
Definition: bgworker.h:98
struct bkend * rw_backend
#define DEBUG1
Definition: elog.h:25
#define SIGUSR1
Definition: win32_port.h:165
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
static void slist_push_head(slist_head *head, slist_node *node)
Definition: ilist.h:574
int bgw_restart_time
Definition: bgworker.h:94
int errcode(int sqlerrcode)
Definition: elog.c:610
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:67
#define kill(pid, sig)
Definition: win32_port.h:426
void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz)
Definition: ascii.c:173
#define LOG
Definition: elog.h:26
char bgw_function_name[BGW_MAXLEN]
Definition: bgworker.h:96
#define malloc(a)
Definition: header.h:50
Datum bgw_main_arg
Definition: bgworker.h:97
void ReportBackgroundWorkerPID(RegisteredBgWorker *rw)
Definition: bgworker.c:439
bool PostmasterMarkPIDForWorkerNotify(int pid)
Definition: postmaster.c:6118
slist_head BackgroundWorkerList
Definition: bgworker.c:42
static RegisteredBgWorker * FindRegisteredWorkerBySlotNumber(int slotno)
Definition: bgworker.c:217
#define ereport(elevel,...)
Definition: elog.h:144
#define pg_memory_barrier()
Definition: atomics.h:145
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:90
BackgroundWorker worker
Definition: bgworker.c:82
#define pg_read_barrier()
Definition: atomics.h:158
#define BGW_MAXLEN
Definition: bgworker.h:85
BgWorkerStartTime bgw_start_time
Definition: bgworker.h:93
char bgw_type[BGW_MAXLEN]
Definition: bgworker.h:91
int errmsg(const char *fmt,...)
Definition: elog.c:824
uint32 parallel_terminate_count
Definition: bgworker.c:100
pid_t bgw_notify_pid
Definition: bgworker.h:99
#define elog(elevel,...)
Definition: elog.h:214
int max_worker_processes
Definition: globals.c:133
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101
char bgw_library_name[BGW_MAXLEN]
Definition: bgworker.h:95
#define BGW_EXTRALEN
Definition: bgworker.h:86

◆ BackgroundWorkerStopNotifications()

void BackgroundWorkerStopNotifications ( pid_t  pid)

Definition at line 492 of file bgworker.c.

References BackgroundWorker::bgw_notify_pid, slist_iter::cur, RegisteredBgWorker::rw_worker, slist_container, and slist_foreach.

Referenced by CleanupBackend(), and CleanupBackgroundWorker().

493 {
494  slist_iter siter;
495 
497  {
498  RegisteredBgWorker *rw;
499 
500  rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
501  if (rw->rw_worker.bgw_notify_pid == pid)
502  rw->rw_worker.bgw_notify_pid = 0;
503  }
504 }
slist_node * cur
Definition: ilist.h:226
slist_head BackgroundWorkerList
Definition: bgworker.c:42
#define slist_container(type, membername, ptr)
Definition: ilist.h:674
#define slist_foreach(iter, lhead)
Definition: ilist.h:700
pid_t bgw_notify_pid
Definition: bgworker.h:99
BackgroundWorker rw_worker

◆ ForgetBackgroundWorker()

void ForgetBackgroundWorker ( slist_mutable_iter cur)

Definition at line 411 of file bgworker.c.

References Assert, BackgroundWorker::bgw_flags, BackgroundWorker::bgw_name, BGWORKER_CLASS_PARALLEL, slist_mutable_iter::cur, DEBUG1, ereport, errmsg(), free, BackgroundWorkerSlot::in_use, max_worker_processes, BackgroundWorkerArray::parallel_terminate_count, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_worker, slist_container, slist_delete_current(), and BackgroundWorkerArray::slot.

Referenced by DetermineSleepTime(), maybe_start_bgworkers(), ReportBackgroundWorkerExit(), and ResetBackgroundWorkerCrashTimes().

412 {
413  RegisteredBgWorker *rw;
414  BackgroundWorkerSlot *slot;
415 
416  rw = slist_container(RegisteredBgWorker, rw_lnode, cur->cur);
417 
422 
423  slot->in_use = false;
424 
425  ereport(DEBUG1,
426  (errmsg("unregistering background worker \"%s\"",
427  rw->rw_worker.bgw_name)));
428 
430  free(rw);
431 }
#define DEBUG1
Definition: elog.h:25
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
slist_node * cur
Definition: ilist.h:241
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:67
#define slist_container(type, membername, ptr)
Definition: ilist.h:674
#define ereport(elevel,...)
Definition: elog.h:144
#define free(a)
Definition: header.h:65
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:90
#define Assert(condition)
Definition: c.h:738
int errmsg(const char *fmt,...)
Definition: elog.c:824
uint32 parallel_terminate_count
Definition: bgworker.c:100
int max_worker_processes
Definition: globals.c:133
static void slist_delete_current(slist_mutable_iter *iter)
Definition: ilist.h:652
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101

◆ ReportBackgroundWorkerExit()

void ReportBackgroundWorkerExit ( slist_mutable_iter cur)

Definition at line 458 of file bgworker.c.

References Assert, BGW_NEVER_RESTART, BackgroundWorker::bgw_notify_pid, BackgroundWorker::bgw_restart_time, slist_mutable_iter::cur, ForgetBackgroundWorker(), kill, max_worker_processes, BackgroundWorkerSlot::pid, RegisteredBgWorker::rw_pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_terminate, RegisteredBgWorker::rw_worker, SIGUSR1, slist_container, and BackgroundWorkerArray::slot.

Referenced by CleanupBackgroundWorker().

459 {
460  RegisteredBgWorker *rw;
461  BackgroundWorkerSlot *slot;
462  int notify_pid;
463 
464  rw = slist_container(RegisteredBgWorker, rw_lnode, cur->cur);
465 
468  slot->pid = rw->rw_pid;
469  notify_pid = rw->rw_worker.bgw_notify_pid;
470 
471  /*
472  * If this worker is slated for deregistration, do that before notifying
473  * the process which started it. Otherwise, if that process tries to
474  * reuse the slot immediately, it might not be available yet. In theory
475  * that could happen anyway if the process checks slot->pid at just the
476  * wrong moment, but this makes the window narrower.
477  */
478  if (rw->rw_terminate ||
481 
482  if (notify_pid != 0)
483  kill(notify_pid, SIGUSR1);
484 }
#define SIGUSR1
Definition: win32_port.h:165
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
slist_node * cur
Definition: ilist.h:241
int bgw_restart_time
Definition: bgworker.h:94
#define kill(pid, sig)
Definition: win32_port.h:426
void ForgetBackgroundWorker(slist_mutable_iter *cur)
Definition: bgworker.c:411
#define BGW_NEVER_RESTART
Definition: bgworker.h:84
#define slist_container(type, membername, ptr)
Definition: ilist.h:674
#define Assert(condition)
Definition: c.h:738
pid_t bgw_notify_pid
Definition: bgworker.h:99
int max_worker_processes
Definition: globals.c:133
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101

◆ ReportBackgroundWorkerPID()

void ReportBackgroundWorkerPID ( RegisteredBgWorker )

Definition at line 439 of file bgworker.c.

References Assert, BackgroundWorker::bgw_notify_pid, kill, max_worker_processes, BackgroundWorkerSlot::pid, RegisteredBgWorker::rw_pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_worker, SIGUSR1, and BackgroundWorkerArray::slot.

Referenced by BackgroundWorkerStateChange(), and do_start_bgworker().

440 {
441  BackgroundWorkerSlot *slot;
442 
443  Assert(rw->rw_shmem_slot < max_worker_processes);
444  slot = &BackgroundWorkerData->slot[rw->rw_shmem_slot];
445  slot->pid = rw->rw_pid;
446 
447  if (rw->rw_worker.bgw_notify_pid != 0)
448  kill(rw->rw_worker.bgw_notify_pid, SIGUSR1);
449 }
#define SIGUSR1
Definition: win32_port.h:165
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
#define kill(pid, sig)
Definition: win32_port.h:426
#define Assert(condition)
Definition: c.h:738
int max_worker_processes
Definition: globals.c:133
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101

◆ ResetBackgroundWorkerCrashTimes()

void ResetBackgroundWorkerCrashTimes ( void  )

Definition at line 514 of file bgworker.c.

References Assert, BackgroundWorker::bgw_flags, BGW_NEVER_RESTART, BackgroundWorker::bgw_restart_time, BGWORKER_CLASS_PARALLEL, slist_mutable_iter::cur, ForgetBackgroundWorker(), BackgroundWorkerSlot::in_use, RegisteredBgWorker::rw_crashed_at, RegisteredBgWorker::rw_worker, slist_container, slist_foreach_modify, BackgroundWorkerArray::slot, and BackgroundWorkerSlot::worker.

Referenced by PostmasterStateMachine().

515 {
516  slist_mutable_iter iter;
517 
519  {
520  RegisteredBgWorker *rw;
521 
522  rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
523 
525  {
526  /*
527  * Workers marked BGW_NEVER_RESTART shouldn't get relaunched after
528  * the crash, so forget about them. (If we wait until after the
529  * crash to forget about them, and they are parallel workers,
530  * parallel_terminate_count will get incremented after we've
531  * already zeroed parallel_register_count, which would be bad.)
532  */
533  ForgetBackgroundWorker(&iter);
534  }
535  else
536  {
537  /*
538  * The accounting which we do via parallel_register_count and
539  * parallel_terminate_count would get messed up if a worker marked
540  * parallel could survive a crash and restart cycle. All such
541  * workers should be marked BGW_NEVER_RESTART, and thus control
542  * should never reach this branch.
543  */
545 
546  /*
547  * Allow this worker to be restarted immediately after we finish
548  * resetting.
549  */
550  rw->rw_crashed_at = 0;
551  }
552  }
553 }
slist_node * cur
Definition: ilist.h:241
int bgw_restart_time
Definition: bgworker.h:94
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:67
#define slist_foreach_modify(iter, lhead)
Definition: ilist.h:716
slist_head BackgroundWorkerList
Definition: bgworker.c:42
void ForgetBackgroundWorker(slist_mutable_iter *cur)
Definition: bgworker.c:411
#define BGW_NEVER_RESTART
Definition: bgworker.h:84
#define slist_container(type, membername, ptr)
Definition: ilist.h:674
#define Assert(condition)
Definition: c.h:738
BackgroundWorker rw_worker

◆ StartBackgroundWorker()

void StartBackgroundWorker ( void  )

Definition at line 680 of file bgworker.c.

References B_BG_WORKER, BaseInit(), BackgroundWorker::bgw_flags, BackgroundWorker::bgw_function_name, BackgroundWorker::bgw_library_name, BackgroundWorker::bgw_main_arg, BackgroundWorker::bgw_name, BGWORKER_BACKEND_DATABASE_CONNECTION, bgworker_die(), BGWORKER_SHMEM_ACCESS, bgworker_sigusr1_handler(), dsm_detach_all(), elog, EmitErrorReport(), error_context_stack, FATAL, FloatExceptionHandler(), HOLD_INTERRUPTS, init_ps_display(), InitializeTimeouts(), InitProcess(), InitProcessing, IsBackgroundWorker, LookupBackgroundWorkerFunction(), MyBackendType, MyBgworkerEntry, PG_exception_stack, pg_usleep(), PGSharedMemoryDetach(), PostAuthDelay, pqsignal(), proc_exit(), procsignal_sigusr1_handler(), SetProcessingMode, SIG_DFL, SIG_IGN, SIGCHLD, SIGHUP, SignalHandlerForCrashExit(), SIGPIPE, SIGQUIT, SIGUSR1, SIGUSR2, StatementCancelHandler(), and BackgroundWorkerSlot::worker.

Referenced by BackendRun(), and do_start_bgworker().

681 {
682  sigjmp_buf local_sigjmp_buf;
684  bgworker_main_type entrypt;
685 
686  if (worker == NULL)
687  elog(FATAL, "unable to find bgworker entry");
688 
689  IsBackgroundWorker = true;
690 
692  init_ps_display(worker->bgw_name);
693 
694  /*
695  * If we're not supposed to have shared memory access, then detach from
696  * shared memory. If we didn't request shared memory access, the
697  * postmaster won't force a cluster-wide restart if we exit unexpectedly,
698  * so we'd better make sure that we don't mess anything up that would
699  * require that sort of cleanup.
700  */
701  if ((worker->bgw_flags & BGWORKER_SHMEM_ACCESS) == 0)
702  {
703  dsm_detach_all();
705  }
706 
708 
709  /* Apply PostAuthDelay */
710  if (PostAuthDelay > 0)
711  pg_usleep(PostAuthDelay * 1000000L);
712 
713  /*
714  * Set up signal handlers.
715  */
717  {
718  /*
719  * SIGINT is used to signal canceling the current action
720  */
724 
725  /* XXX Any other handlers needed here? */
726  }
727  else
728  {
729  pqsignal(SIGINT, SIG_IGN);
731  pqsignal(SIGFPE, SIG_IGN);
732  }
733  pqsignal(SIGTERM, bgworker_die);
735 
737  InitializeTimeouts(); /* establishes SIGALRM handler */
738 
742 
743  /*
744  * If an exception is encountered, processing resumes here.
745  *
746  * See notes in postgres.c about the design of this coding.
747  */
748  if (sigsetjmp(local_sigjmp_buf, 1) != 0)
749  {
750  /* Since not using PG_TRY, must reset error stack by hand */
751  error_context_stack = NULL;
752 
753  /* Prevent interrupts while cleaning up */
754  HOLD_INTERRUPTS();
755 
756  /* Report the error to the server log */
757  EmitErrorReport();
758 
759  /*
760  * Do we need more cleanup here? For shmem-connected bgworkers, we
761  * will call InitProcess below, which will install ProcKill as exit
762  * callback. That will take care of releasing locks, etc.
763  */
764 
765  /* and go away */
766  proc_exit(1);
767  }
768 
769  /* We can now handle ereport(ERROR) */
770  PG_exception_stack = &local_sigjmp_buf;
771 
772  /*
773  * If the background worker request shared memory access, set that up now;
774  * else, detach all shared memory segments.
775  */
776  if (worker->bgw_flags & BGWORKER_SHMEM_ACCESS)
777  {
778  /*
779  * Early initialization. Some of this could be useful even for
780  * background workers that aren't using shared memory, but they can
781  * call the individual startup routines for those subsystems if
782  * needed.
783  */
784  BaseInit();
785 
786  /*
787  * Create a per-backend PGPROC struct in shared memory, except in the
788  * EXEC_BACKEND case where this was done in SubPostmasterMain. We must
789  * do this before we can use LWLocks (and in the EXEC_BACKEND case we
790  * already had to do some stuff with LWLocks).
791  */
792 #ifndef EXEC_BACKEND
793  InitProcess();
794 #endif
795  }
796 
797  /*
798  * Look up the entry point function, loading its library if necessary.
799  */
801  worker->bgw_function_name);
802 
803  /*
804  * Note that in normal processes, we would call InitPostgres here. For a
805  * worker, however, we don't know what database to connect to, yet; so we
806  * need to wait until the user code does it via
807  * BackgroundWorkerInitializeConnection().
808  */
809 
810  /*
811  * Now invoke the user-defined worker code
812  */
813  entrypt(worker->bgw_main_arg);
814 
815  /* ... and if it returns, we're done */
816  proc_exit(0);
817 }
void InitializeTimeouts(void)
Definition: timeout.c:346
static void bgworker_sigusr1_handler(SIGNAL_ARGS)
Definition: bgworker.c:664
#define SIGQUIT
Definition: win32_port.h:154
#define SIGUSR1
Definition: win32_port.h:165
BackendType MyBackendType
Definition: miscinit.c:60
#define SIGCHLD
Definition: win32_port.h:163
void proc_exit(int code)
Definition: ipc.c:104
#define SetProcessingMode(mode)
Definition: miscadmin.h:398
BackgroundWorker * MyBgworkerEntry
Definition: postmaster.c:192
void BaseInit(void)
Definition: postinit.c:548
#define SIGPIPE
Definition: win32_port.h:158
#define SIGUSR2
Definition: win32_port.h:166
#define BGWORKER_SHMEM_ACCESS
Definition: bgworker.h:52
char bgw_function_name[BGW_MAXLEN]
Definition: bgworker.h:96
void PGSharedMemoryDetach(void)
Definition: sysv_shmem.c:881
void StatementCancelHandler(SIGNAL_ARGS)
Definition: postgres.c:2857
bool IsBackgroundWorker
Definition: globals.c:111
ErrorContextCallback * error_context_stack
Definition: elog.c:92
void pg_usleep(long microsec)
Definition: signal.c:53
Datum bgw_main_arg
Definition: bgworker.h:97
void SignalHandlerForCrashExit(SIGNAL_ARGS)
Definition: interrupt.c:72
#define FATAL
Definition: elog.h:52
void InitProcess(void)
Definition: proc.c:304
#define SIGHUP
Definition: win32_port.h:153
static bgworker_main_type LookupBackgroundWorkerFunction(const char *libraryname, const char *funcname)
Definition: bgworker.c:1197
#define SIG_IGN
Definition: win32_port.h:150
int PostAuthDelay
Definition: postgres.c:102
void EmitErrorReport(void)
Definition: elog.c:1423
pqsigfunc pqsignal(int signum, pqsigfunc handler)
Definition: signal.c:170
#define SIG_DFL
Definition: win32_port.h:148
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:90
#define BGWORKER_BACKEND_DATABASE_CONNECTION
Definition: bgworker.h:59
void dsm_detach_all(void)
Definition: dsm.c:630
sigjmp_buf * PG_exception_stack
Definition: elog.c:94
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:116
#define elog(elevel,...)
Definition: elog.h:214
void FloatExceptionHandler(SIGNAL_ARGS)
Definition: postgres.c:2878
static void bgworker_die(SIGNAL_ARGS)
Definition: bgworker.c:647
void init_ps_display(const char *fixed_part)
Definition: ps_status.c:258
void procsignal_sigusr1_handler(SIGNAL_ARGS)
Definition: procsignal.c:533
char bgw_library_name[BGW_MAXLEN]
Definition: bgworker.h:95
void(* bgworker_main_type)(Datum main_arg)
Definition: bgworker.h:71

Variable Documentation

◆ BackgroundWorkerList

slist_head BackgroundWorkerList