#include "postgres.h"
#include "libpq/pqsignal.h"

Include dependency graph for signal.c:

Functions
static DWORD WINAPI	pg_signal_thread (LPVOID param)

static BOOL WINAPI	pg_console_handler (DWORD dwCtrlType)

void	pg_usleep (long microsec)

void	pgwin32_signal_initialize (void)

void	pgwin32_dispatch_queued_signals (void)

int	pqsigsetmask (int mask)

pqsigfunc	pqsignal (int signum, pqsigfunc handler)

HANDLE	pgwin32_create_signal_listener (pid_t pid)

void	pg_queue_signal (int signum)

static DWORD WINAPI	pg_signal_dispatch_thread (LPVOID param)

Variables
volatile int	pg_signal_queue

int	pg_signal_mask

HANDLE	pgwin32_signal_event

HANDLE	pgwin32_initial_signal_pipe = INVALID_HANDLE_VALUE

static CRITICAL_SECTION	pg_signal_crit_sec

static pqsigfunc	pg_signal_array [PG_SIGNAL_COUNT]

static pqsigfunc	pg_signal_defaults [PG_SIGNAL_COUNT]

Function Documentation

◆ pg_console_handler()

static BOOL WINAPI pg_console_handler ( DWORD dwCtrlType )

static

Definition at line 348 of file signal.c.

References FALSE, pg_queue_signal(), and TRUE.

Referenced by pgwin32_signal_initialize().

 {
     if (dwCtrlType == CTRL_C_EVENT ||
         dwCtrlType == CTRL_BREAK_EVENT ||
         dwCtrlType == CTRL_CLOSE_EVENT ||
         dwCtrlType == CTRL_SHUTDOWN_EVENT)
     {
         pg_queue_signal(SIGINT);
         return TRUE;
     }
     return FALSE;
 }

◆ pg_queue_signal()

void pg_queue_signal ( int signum )

Definition at line 210 of file signal.c.

References PG_SIGNAL_COUNT, pg_signal_crit_sec, pg_signal_queue, pgwin32_signal_event, and sigmask.

Referenced by pg_console_handler(), pg_signal_dispatch_thread(), pg_timer_thread(), and PostmasterMarkPIDForWorkerNotify().

 {
     if (signum >= PG_SIGNAL_COUNT || signum <= 0)
         return;
 
     EnterCriticalSection(&pg_signal_crit_sec);
     pg_signal_queue |= sigmask(signum);
     LeaveCriticalSection(&pg_signal_crit_sec);
 
     SetEvent(pgwin32_signal_event);
 }

◆ pg_signal_dispatch_thread()

static DWORD WINAPI pg_signal_dispatch_thread ( LPVOID param )

static

Definition at line 224 of file signal.c.

References pg_queue_signal().

Referenced by pg_signal_thread().

 {
     HANDLE      pipe = (HANDLE) param;
     BYTE        sigNum;
     DWORD       bytes;
 
     if (!ReadFile(pipe, &sigNum, 1, &bytes, NULL))
     {
         /* Client died before sending */
         CloseHandle(pipe);
         return 0;
     }
     if (bytes != 1)
     {
         /* Received <bytes> bytes over signal pipe (should be 1) */
         CloseHandle(pipe);
         return 0;
     }
     WriteFile(pipe, &sigNum, 1, &bytes, NULL);  /* Don't care if it works or
                                                  * not.. */
     FlushFileBuffers(pipe);
     DisconnectNamedPipe(pipe);
     CloseHandle(pipe);
 
     pg_queue_signal(sigNum);
     return 0;
 }

◆ pg_signal_thread()

static DWORD WINAPI pg_signal_thread ( LPVOID param )

static

Definition at line 254 of file signal.c.

References FALSE, pg_signal_dispatch_thread(), pgwin32_initial_signal_pipe, snprintf(), TRUE, and write_stderr.

Referenced by pgwin32_signal_initialize().

 {
     char        pipename[128];
     HANDLE      pipe = pgwin32_initial_signal_pipe;
 
     snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%lu", GetCurrentProcessId());
 
     for (;;)
     {
         BOOL        fConnected;
         HANDLE      hThread;
 
         if (pipe == INVALID_HANDLE_VALUE)
         {
             pipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
                                    PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
                                    PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);
 
             if (pipe == INVALID_HANDLE_VALUE)
             {
                 write_stderr("could not create signal listener pipe: error code %lu; retrying\n", GetLastError());
                 SleepEx(500, FALSE);
                 continue;
             }
         }
 
         fConnected = ConnectNamedPipe(pipe, NULL) ? TRUE : (GetLastError() == ERROR_PIPE_CONNECTED);
         if (fConnected)
         {
             HANDLE      newpipe;
 
             /*
              * We have a connected pipe. Pass this off to a separate thread
              * that will do the actual processing of the pipe.
              *
              * We must also create a new instance of the pipe *before* we
              * start running the new thread. If we don't, there is a race
              * condition whereby the dispatch thread might run CloseHandle()
              * before we have created a new instance, thereby causing a small
              * window of time where we will miss incoming requests.
              */
             newpipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
                                       PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
                                       PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);
             if (newpipe == INVALID_HANDLE_VALUE)
             {
                 /*
                  * This really should never fail. Just retry in case it does,
                  * even though we have a small race window in that case. There
                  * is nothing else we can do other than abort the whole
                  * process which will be even worse.
                  */
                 write_stderr("could not create signal listener pipe: error code %lu; retrying\n", GetLastError());
 
                 /*
                  * Keep going so we at least dispatch this signal. Hopefully,
                  * the call will succeed when retried in the loop soon after.
                  */
             }
             hThread = CreateThread(NULL, 0,
                                    (LPTHREAD_START_ROUTINE) pg_signal_dispatch_thread,
                                    (LPVOID) pipe, 0, NULL);
             if (hThread == INVALID_HANDLE_VALUE)
                 write_stderr("could not create signal dispatch thread: error code %lu\n",
                              GetLastError());
             else
                 CloseHandle(hThread);
 
             /*
              * Background thread is running with our instance of the pipe. So
              * replace our reference with the newly created one and loop back
              * up for another run.
              */
             pipe = newpipe;
         }
         else
         {
             /*
              * Connection failed. Cleanup and try again.
              *
              * This should never happen. If it does, we have a small race
              * condition until we loop up and re-create the pipe.
              */
             CloseHandle(pipe);
             pipe = INVALID_HANDLE_VALUE;
         }
     }
     return 0;
 }

◆ pg_usleep()

void pg_usleep ( long microsec )

Definition at line 53 of file signal.c.

Referenced by auth_delay_checks(), AutoVacLauncherMain(), AutoVacWorkerMain(), backend_read_statsfile(), BackendInitialize(), BackgroundWriterMain(), CheckpointerMain(), CheckpointWriteDelay(), ConditionalXactLockTableWait(), CountOtherDBBackends(), CreateCheckPoint(), CustomizableNextWALFileReady(), do_pg_stop_backup(), do_promote(), do_restart(), do_stop(), do_watch(), exec_prog(), FileRead(), FileWrite(), ForgetDatabaseFsyncRequests(), ForgetRelationFsyncRequests(), GetMultiXactIdMembers(), InitPostgres(), lazy_truncate_heap(), main(), perform_spin_delay(), pgarch_ArchiverCopyLoop(), pgwin32_recv(), read_local_xlog_page(), recoveryPausesHere(), register_unlink(), regression_main(), RequestCheckpoint(), ResolveRecoveryConflictWithDatabase(), ResolveRecoveryConflictWithVirtualXIDs(), RestoreWALFileForRecovery(), ServerLoop(), ShutdownWalRcv(), StartBackgroundWorker(), StartupXLOG(), StreamConnection(), threadRun(), vacuum_delay_point(), wait_for_postmaster(), wait_pid(), WaitExceedsMaxStandbyDelay(), WalSndWaitStopping(), WalWriterMain(), XactLockTableWait(), XLogDumpXLogRead(), and XLogFlush().

 {
     if (WaitForSingleObject(pgwin32_signal_event,
                             (microsec < 500 ? 1 : (microsec + 500) / 1000))
         == WAIT_OBJECT_0)
     {
         pgwin32_dispatch_queued_signals();
         errno = EINTR;
         return;
     }
 }

◆ pgwin32_create_signal_listener()

HANDLE pgwin32_create_signal_listener ( pid_t pid )

Definition at line 181 of file signal.c.

References ereport, errmsg(), ERROR, and snprintf().

Referenced by PostmasterMarkPIDForWorkerNotify().

 {
     char        pipename[128];
     HANDLE      pipe;
 
     snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%u", (int) pid);
 
     pipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
                            PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
                            PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);
 
     if (pipe == INVALID_HANDLE_VALUE)
         ereport(ERROR,
                 (errmsg("could not create signal listener pipe for PID %d: error code %lu",
                         (int) pid, GetLastError())));
 
     return pipe;
 }

◆ pgwin32_dispatch_queued_signals()

void pgwin32_dispatch_queued_signals ( void )

Definition at line 107 of file signal.c.

References i, pg_signal_array, PG_SIGNAL_COUNT, pg_signal_crit_sec, pg_signal_defaults, pg_signal_queue, pgwin32_signal_event, sig, SIG_DFL, SIG_ERR, SIG_IGN, sigmask, and UNBLOCKED_SIGNAL_QUEUE.

Referenced by pg_usleep(), PGSemaphoreLock(), pgwin32_poll_signals(), pgwin32_select(), pgwin32_waitforsinglesocket(), pqsigsetmask(), and WaitEventSetWait().

 {
     int         exec_mask;
 
     EnterCriticalSection(&pg_signal_crit_sec);
     while ((exec_mask = UNBLOCKED_SIGNAL_QUEUE()) != 0)
     {
         /* One or more unblocked signals queued for execution */
         int         i;
 
         for (i = 1; i < PG_SIGNAL_COUNT; i++)
         {
             if (exec_mask & sigmask(i))
             {
                 /* Execute this signal */
                 pqsigfunc   sig = pg_signal_array[i];
 
                 if (sig == SIG_DFL)
                     sig = pg_signal_defaults[i];
                 pg_signal_queue &= ~sigmask(i);
                 if (sig != SIG_ERR && sig != SIG_IGN && sig != SIG_DFL)
                 {
                     LeaveCriticalSection(&pg_signal_crit_sec);
                     sig(i);
                     EnterCriticalSection(&pg_signal_crit_sec);
                     break;      /* Restart outer loop, in case signal mask or
                                  * queue has been modified inside signal
                                  * handler */
                 }
             }
         }
     }
     ResetEvent(pgwin32_signal_event);
     LeaveCriticalSection(&pg_signal_crit_sec);
 }

◆ pgwin32_signal_initialize()

void pgwin32_signal_initialize ( void )

Definition at line 68 of file signal.c.

References ereport, errmsg_internal(), FALSE, FATAL, i, pg_console_handler(), pg_signal_array, PG_SIGNAL_COUNT, pg_signal_crit_sec, pg_signal_defaults, pg_signal_mask, pg_signal_queue, pg_signal_thread(), pgwin32_signal_event, SIG_DFL, SIG_IGN, and TRUE.

Referenced by BackendRun(), and main().

 {
     int         i;
     HANDLE      signal_thread_handle;
 
     InitializeCriticalSection(&pg_signal_crit_sec);
 
     for (i = 0; i < PG_SIGNAL_COUNT; i++)
     {
         pg_signal_array[i] = SIG_DFL;
         pg_signal_defaults[i] = SIG_IGN;
     }
     pg_signal_mask = 0;
     pg_signal_queue = 0;
 
     /* Create the global event handle used to flag signals */
     pgwin32_signal_event = CreateEvent(NULL, TRUE, FALSE, NULL);
     if (pgwin32_signal_event == NULL)
         ereport(FATAL,
                 (errmsg_internal("could not create signal event: error code %lu", GetLastError())));
 
     /* Create thread for handling signals */
     signal_thread_handle = CreateThread(NULL, 0, pg_signal_thread, NULL, 0, NULL);
     if (signal_thread_handle == NULL)
         ereport(FATAL,
                 (errmsg_internal("could not create signal handler thread")));
 
     /* Create console control handle to pick up Ctrl-C etc */
     if (!SetConsoleCtrlHandler(pg_console_handler, TRUE))
         ereport(FATAL,
                 (errmsg_internal("could not set console control handler")));
 }

◆ pqsignal()

pqsigfunc pqsignal	(	int	signum,
		pqsigfunc	handler
	)

Definition at line 168 of file signal.c.

Referenced by ApplyLauncherMain(), ApplyWorkerMain(), autoprewarm_database_main(), autoprewarm_main(), AutoVacLauncherMain(), AutoVacWorkerMain(), BackendInitialize(), BackgroundWriterMain(), bootstrap_signals(), CheckpointerMain(), disable_sigpipe_trap(), initialize_worker_spi(), InitializeTimeouts(), main(), ParallelBackupStart(), ParallelWorkerMain(), pg_crc32c_armv8_available(), PgArchiverMain(), PgstatCollectorMain(), plperl_init_interp(), PostgresMain(), PostmasterMain(), PQprint(), restore_sigpipe_trap(), setalarm(), setup_cancel_handler(), setup_signals(), sigquit_handler(), sigTermHandler(), StartBackgroundWorker(), StartupProcessMain(), stop_postmaster(), SysLoggerMain(), test_shm_mq_main(), trapsig(), WalReceiverMain(), WalSndSignals(), and WalWriterMain().

 {
     pqsigfunc   prevfunc;
 
     if (signum >= PG_SIGNAL_COUNT || signum < 0)
         return SIG_ERR;
     prevfunc = pg_signal_array[signum];
     pg_signal_array[signum] = handler;
     return prevfunc;
 }

◆ pqsigsetmask()

int pqsigsetmask ( int mask )

Definition at line 145 of file signal.c.

References pg_signal_mask, and pgwin32_dispatch_queued_signals().

 {
     int         prevmask;
 
     prevmask = pg_signal_mask;
     pg_signal_mask = mask;
 
     /*
      * Dispatch any signals queued up right away, in case we have unblocked
      * one or more signals previously queued
      */
     pgwin32_dispatch_queued_signals();
 
     return prevmask;
 }