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Move more bgworker code to bgworker.c; also, some renaming. 

Per discussion on pgsql-hackers.

Michael Paquier, slightly modified by me.  Original suggestion
from Amit Kapila.
This commit is contained in:
Robert Haas 2013-08-16 15:14:54 -04:00
parent ac76ec27b9
commit 2dee7998f9
3 changed files with 232 additions and 213 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

219
src/backend/postmaster/bgworker.c
View File

@ -12,13 +12,24 @@
#include "postgres.h"
#include <unistd.h>
#include <time.h>
#include "miscadmin.h"
#include "libpq/pqsignal.h"
#include "postmaster/bgworker_internals.h"
#include "storage/barrier.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/lwlock.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/procsignal.h"
#include "storage/shmem.h"
#include "tcop/tcopprot.h"
#include "utils/ascii.h"
#include "utils/ps_status.h"
#include "utils/timeout.h"
/*
* The postmaster's list of registered background workers, in private memory.
@ -354,6 +365,214 @@ SanityCheckBackgroundWorker(BackgroundWorker *worker, int elevel)
return true;
}
static void
bgworker_quickdie(SIGNAL_ARGS)
{
sigaddset(&BlockSig, SIGQUIT); /* prevent nested calls */
PG_SETMASK(&BlockSig);
/*
* We DO NOT want to run proc_exit() callbacks -- we're here because
* shared memory may be corrupted, so we don't want to try to clean up our
* transaction. Just nail the windows shut and get out of town. Now that
* there's an atexit callback to prevent third-party code from breaking
* things by calling exit() directly, we have to reset the callbacks
* explicitly to make this work as intended.
*/
on_exit_reset();
/*
* Note we do exit(0) here, not exit(2) like quickdie. The reason is that
* we don't want to be seen this worker as independently crashed, because
* then postmaster would delay restarting it again afterwards. If some
* idiot DBA manually sends SIGQUIT to a random bgworker, the "dead man
* switch" will ensure that postmaster sees this as a crash.
*/
exit(0);
}
/*
* Standard SIGTERM handler for background workers
*/
static void
bgworker_die(SIGNAL_ARGS)
{
PG_SETMASK(&BlockSig);
ereport(FATAL,
(errcode(ERRCODE_ADMIN_SHUTDOWN),
errmsg("terminating background worker \"%s\" due to administrator command",
MyBgworkerEntry->bgw_name)));
}
/*
* Standard SIGUSR1 handler for unconnected workers
*
* Here, we want to make sure an unconnected worker will at least heed
* latch activity.
*/
static void
bgworker_sigusr1_handler(SIGNAL_ARGS)
{
int save_errno = errno;
latch_sigusr1_handler();
errno = save_errno;
}
/*
* Start a new background worker
*
* This is the main entry point for background worker, to be called from
* postmaster.
*/
void
StartBackgroundWorker(void)
{
sigjmp_buf local_sigjmp_buf;
char buf[MAXPGPATH];
BackgroundWorker *worker = MyBgworkerEntry;
bgworker_main_type entrypt;
if (worker == NULL)
elog(FATAL, "unable to find bgworker entry");
/* we are a postmaster subprocess now */
IsUnderPostmaster = true;
IsBackgroundWorker = true;
/* reset MyProcPid */
MyProcPid = getpid();
/* record Start Time for logging */
MyStartTime = time(NULL);
/* Identify myself via ps */
snprintf(buf, MAXPGPATH, "bgworker: %s", worker->bgw_name);
init_ps_display(buf, "", "", "");
SetProcessingMode(InitProcessing);
/* Apply PostAuthDelay */
if (PostAuthDelay > 0)
pg_usleep(PostAuthDelay * 1000000L);
/*
* If possible, make this process a group leader, so that the postmaster
* can signal any child processes too.
*/
#ifdef HAVE_SETSID
if (setsid() < 0)
elog(FATAL, "setsid() failed: %m");
#endif
/*
* Set up signal handlers.
*/
if (worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)
{
/*
* SIGINT is used to signal canceling the current action
*/
pqsignal(SIGINT, StatementCancelHandler);
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGFPE, FloatExceptionHandler);
/* XXX Any other handlers needed here? */
}
else
{
pqsignal(SIGINT, SIG_IGN);
pqsignal(SIGUSR1, bgworker_sigusr1_handler);
pqsignal(SIGFPE, SIG_IGN);
}
pqsignal(SIGTERM, bgworker_die);
pqsignal(SIGHUP, SIG_IGN);
pqsignal(SIGQUIT, bgworker_quickdie);
InitializeTimeouts(); /* establishes SIGALRM handler */
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR2, SIG_IGN);
pqsignal(SIGCHLD, SIG_DFL);
/*
* If an exception is encountered, processing resumes here.
*
* See notes in postgres.c about the design of this coding.
*/
if (sigsetjmp(local_sigjmp_buf, 1) != 0)
{
/* Since not using PG_TRY, must reset error stack by hand */
error_context_stack = NULL;
/* Prevent interrupts while cleaning up */
HOLD_INTERRUPTS();
/* Report the error to the server log */
EmitErrorReport();
/*
* Do we need more cleanup here? For shmem-connected bgworkers, we
* will call InitProcess below, which will install ProcKill as exit
* callback. That will take care of releasing locks, etc.
*/
/* and go away */
proc_exit(1);
}
/* We can now handle ereport(ERROR) */
PG_exception_stack = &local_sigjmp_buf;
/* Early initialization */
BaseInit();
/*
* If necessary, create a per-backend PGPROC struct in shared memory,
* except in the EXEC_BACKEND case where this was done in
* SubPostmasterMain. We must do this before we can use LWLocks (and in
* the EXEC_BACKEND case we already had to do some stuff with LWLocks).
*/
#ifndef EXEC_BACKEND
if (worker->bgw_flags & BGWORKER_SHMEM_ACCESS)
InitProcess();
#endif
/*
* If bgw_main is set, we use that value as the initial entrypoint.
* However, if the library containing the entrypoint wasn't loaded at
* postmaster startup time, passing it as a direct function pointer is
* not possible. To work around that, we allow callers for whom a
* function pointer is not available to pass a library name (which will
* be loaded, if necessary) and a function name (which will be looked up
* in the named library).
*/
if (worker->bgw_main != NULL)
entrypt = worker->bgw_main;
else
entrypt = (bgworker_main_type)
load_external_function(worker->bgw_library_name,
worker->bgw_function_name,
true, NULL);
/*
* Note that in normal processes, we would call InitPostgres here. For a
* worker, however, we don't know what database to connect to, yet; so we
* need to wait until the user code does it via
* BackgroundWorkerInitializeConnection().
*/
/*
* Now invoke the user-defined worker code
*/
entrypt(worker->bgw_main_arg);
/* ... and if it returns, we're done */
proc_exit(0);
}
/*
* Register a new background worker while processing shared_preload_libraries.
*

223
src/backend/postmaster/postmaster.c
View File

@ -383,7 +383,6 @@ static void dummy_handler(SIGNAL_ARGS);
static void StartupPacketTimeoutHandler(void);
static void CleanupBackend(int pid, int exitstatus);
static bool CleanupBackgroundWorker(int pid, int exitstatus);
static void do_start_bgworker(void);
static void HandleChildCrash(int pid, int exitstatus, const char *procname);
static void LogChildExit(int lev, const char *procname,
int pid, int exitstatus);
@ -409,7 +408,7 @@ static void TerminateChildren(int signal);
static int CountChildren(int target);
static int CountUnconnectedWorkers(void);
static void StartOneBackgroundWorker(void);
static void maybe_start_bgworker(void);
static bool CreateOptsFile(int argc, char *argv[], char *fullprogname);
static pid_t StartChildProcess(AuxProcType type);
static void StartAutovacuumWorker(void);
@ -1232,7 +1231,7 @@ PostmasterMain(int argc, char *argv[])
pmState = PM_STARTUP;
/* Some workers may be scheduled to start now */
StartOneBackgroundWorker();
maybe_start_bgworker();
status = ServerLoop();
@ -1650,7 +1649,7 @@ ServerLoop(void)
/* Get other worker processes running, if needed */
if (StartWorkerNeeded || HaveCrashedWorker)
StartOneBackgroundWorker();
maybe_start_bgworker();
/*
* Touch Unix socket and lock files every 58 minutes, to ensure that
@ -2610,7 +2609,7 @@ reaper(SIGNAL_ARGS)
PgStatPID = pgstat_start();
/* some workers may be scheduled to start now */
StartOneBackgroundWorker();
maybe_start_bgworker();
/* at this point we are really open for business */
ereport(LOG,
@ -4626,7 +4625,7 @@ SubPostmasterMain(int argc, char *argv[])
shmem_slot = atoi(argv[1] + 15);
MyBgworkerEntry = BackgroundWorkerEntry(shmem_slot);
do_start_bgworker();
StartBackgroundWorker();
}
if (strcmp(argv[1], "--forkarch") == 0)
{
@ -4741,7 +4740,7 @@ sigusr1_handler(SIGNAL_ARGS)
}
if (start_bgworker)
StartOneBackgroundWorker();
maybe_start_bgworker();
if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER) &&
PgArchPID != 0)
@ -5253,208 +5252,6 @@ BackgroundWorkerUnblockSignals(void)
PG_SETMASK(&UnBlockSig);
}
static void
bgworker_quickdie(SIGNAL_ARGS)
{
sigaddset(&BlockSig, SIGQUIT); /* prevent nested calls */
PG_SETMASK(&BlockSig);
/*
* We DO NOT want to run proc_exit() callbacks -- we're here because
* shared memory may be corrupted, so we don't want to try to clean up our
* transaction. Just nail the windows shut and get out of town. Now that
* there's an atexit callback to prevent third-party code from breaking
* things by calling exit() directly, we have to reset the callbacks
* explicitly to make this work as intended.
*/
on_exit_reset();
/*
* Note we do exit(0) here, not exit(2) like quickdie. The reason is that
* we don't want to be seen this worker as independently crashed, because
* then postmaster would delay restarting it again afterwards. If some
* idiot DBA manually sends SIGQUIT to a random bgworker, the "dead man
* switch" will ensure that postmaster sees this as a crash.
*/
exit(0);
}
/*
* Standard SIGTERM handler for background workers
*/
static void
bgworker_die(SIGNAL_ARGS)
{
PG_SETMASK(&BlockSig);
ereport(FATAL,
(errcode(ERRCODE_ADMIN_SHUTDOWN),
errmsg("terminating background worker \"%s\" due to administrator command",
MyBgworkerEntry->bgw_name)));
}
/*
* Standard SIGUSR1 handler for unconnected workers
*
* Here, we want to make sure an unconnected worker will at least heed
* latch activity.
*/
static void
bgworker_sigusr1_handler(SIGNAL_ARGS)
{
int save_errno = errno;
latch_sigusr1_handler();
errno = save_errno;
}
static void
do_start_bgworker(void)
{
sigjmp_buf local_sigjmp_buf;
char buf[MAXPGPATH];
BackgroundWorker *worker = MyBgworkerEntry;
bgworker_main_type entrypt;
if (worker == NULL)
elog(FATAL, "unable to find bgworker entry");
/* we are a postmaster subprocess now */
IsUnderPostmaster = true;
IsBackgroundWorker = true;
/* reset MyProcPid */
MyProcPid = getpid();
/* record Start Time for logging */
MyStartTime = time(NULL);
/* Identify myself via ps */
snprintf(buf, MAXPGPATH, "bgworker: %s", worker->bgw_name);
init_ps_display(buf, "", "", "");
SetProcessingMode(InitProcessing);
/* Apply PostAuthDelay */
if (PostAuthDelay > 0)
pg_usleep(PostAuthDelay * 1000000L);
/*
* If possible, make this process a group leader, so that the postmaster
* can signal any child processes too.
*/
#ifdef HAVE_SETSID
if (setsid() < 0)
elog(FATAL, "setsid() failed: %m");
#endif
/*
* Set up signal handlers.
*/
if (worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)
{
/*
* SIGINT is used to signal canceling the current action
*/
pqsignal(SIGINT, StatementCancelHandler);
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGFPE, FloatExceptionHandler);
/* XXX Any other handlers needed here? */
}
else
{
pqsignal(SIGINT, SIG_IGN);
pqsignal(SIGUSR1, bgworker_sigusr1_handler);
pqsignal(SIGFPE, SIG_IGN);
}
pqsignal(SIGTERM, bgworker_die);
pqsignal(SIGHUP, SIG_IGN);
pqsignal(SIGQUIT, bgworker_quickdie);
InitializeTimeouts(); /* establishes SIGALRM handler */
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR2, SIG_IGN);
pqsignal(SIGCHLD, SIG_DFL);
/*
* If an exception is encountered, processing resumes here.
*
* See notes in postgres.c about the design of this coding.
*/
if (sigsetjmp(local_sigjmp_buf, 1) != 0)
{
/* Since not using PG_TRY, must reset error stack by hand */
error_context_stack = NULL;
/* Prevent interrupts while cleaning up */
HOLD_INTERRUPTS();
/* Report the error to the server log */
EmitErrorReport();
/*
* Do we need more cleanup here? For shmem-connected bgworkers, we
* will call InitProcess below, which will install ProcKill as exit
* callback. That will take care of releasing locks, etc.
*/
/* and go away */
proc_exit(1);
}
/* We can now handle ereport(ERROR) */
PG_exception_stack = &local_sigjmp_buf;
/* Early initialization */
BaseInit();
/*
* If necessary, create a per-backend PGPROC struct in shared memory,
* except in the EXEC_BACKEND case where this was done in
* SubPostmasterMain. We must do this before we can use LWLocks (and in
* the EXEC_BACKEND case we already had to do some stuff with LWLocks).
*/
#ifndef EXEC_BACKEND
if (worker->bgw_flags & BGWORKER_SHMEM_ACCESS)
InitProcess();
#endif
/*
* If bgw_main is set, we use that value as the initial entrypoint.
* However, if the library containing the entrypoint wasn't loaded at
* postmaster startup time, passing it as a direct function pointer is
* not possible. To work around that, we allow callers for whom a
* function pointer is not available to pass a library name (which will
* be loaded, if necessary) and a function name (which will be looked up
* in the named library).
*/
if (worker->bgw_main != NULL)
entrypt = worker->bgw_main;
else
entrypt = (bgworker_main_type)
load_external_function(worker->bgw_library_name,
worker->bgw_function_name,
true, NULL);
/*
* Note that in normal processes, we would call InitPostgres here. For a
* worker, however, we don't know what database to connect to, yet; so we
* need to wait until the user code does it via
* BackgroundWorkerInitializeConnection().
*/
/*
* Now invoke the user-defined worker code
*/
entrypt(worker->bgw_main_arg);
/* ... and if it returns, we're done */
proc_exit(0);
}
#ifdef EXEC_BACKEND
static pid_t
bgworker_forkexec(int shmem_slot)
@ -5483,7 +5280,7 @@ bgworker_forkexec(int shmem_slot)
* This code is heavily based on autovacuum.c, q.v.
*/
static void
start_bgworker(RegisteredBgWorker *rw)
do_start_bgworker(RegisteredBgWorker *rw)
{
pid_t worker_pid;
@ -5514,7 +5311,7 @@ start_bgworker(RegisteredBgWorker *rw)
/* Do NOT release postmaster's working memory context */
MyBgworkerEntry = &rw->rw_worker;
do_start_bgworker();
StartBackgroundWorker();
break;
#endif
default:
@ -5618,7 +5415,7 @@ assign_backendlist_entry(RegisteredBgWorker *rw)
* system state requires it.
*/
static void
StartOneBackgroundWorker(void)
maybe_start_bgworker(void)
{
slist_mutable_iter iter;
TimestampTz now = 0;
@ -5689,7 +5486,7 @@ StartOneBackgroundWorker(void)
else
rw->rw_child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
start_bgworker(rw); /* sets rw->rw_pid */
do_start_bgworker(rw); /* sets rw->rw_pid */
if (rw->rw_backend)
{

3
src/include/postmaster/bgworker_internals.h
View File

@ -41,6 +41,9 @@ extern void BackgroundWorkerShmemInit(void);
extern void BackgroundWorkerStateChange(void);
extern void ForgetBackgroundWorker(slist_mutable_iter *cur);
/* Function to start a background worker, called from postmaster.c */
extern void StartBackgroundWorker(void);
#ifdef EXEC_BACKEND
extern BackgroundWorker *BackgroundWorkerEntry(int slotno);
#endif