procsignal.h File Reference

#include "storage/backendid.h"

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Enumerations
enum	ProcSignalReason {   PROCSIG_CATCHUP_INTERRUPT, PROCSIG_NOTIFY_INTERRUPT, PROCSIG_PARALLEL_MESSAGE, PROCSIG_WALSND_INIT_STOPPING,   PROCSIG_RECOVERY_CONFLICT_DATABASE, PROCSIG_RECOVERY_CONFLICT_TABLESPACE, PROCSIG_RECOVERY_CONFLICT_LOCK, PROCSIG_RECOVERY_CONFLICT_SNAPSHOT,   PROCSIG_RECOVERY_CONFLICT_BUFFERPIN, PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK, NUM_PROCSIGNALS }

Functions
Size	ProcSignalShmemSize (void)
void	ProcSignalShmemInit (void)
void	ProcSignalInit (int pss_idx)
int	SendProcSignal (pid_t pid, ProcSignalReason reason, BackendId backendId)
void	procsignal_sigusr1_handler (SIGNAL_ARGS)

Enumeration Type Documentation

ProcSignalReason

enum ProcSignalReason

Enumerator
PROCSIG_CATCHUP_INTERRUPT
PROCSIG_NOTIFY_INTERRUPT
PROCSIG_PARALLEL_MESSAGE
PROCSIG_WALSND_INIT_STOPPING
PROCSIG_RECOVERY_CONFLICT_DATABASE
PROCSIG_RECOVERY_CONFLICT_TABLESPACE
PROCSIG_RECOVERY_CONFLICT_LOCK
PROCSIG_RECOVERY_CONFLICT_SNAPSHOT
PROCSIG_RECOVERY_CONFLICT_BUFFERPIN
PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK
NUM_PROCSIGNALS

Definition at line 30 of file procsignal.h.

{
    PROCSIG_CATCHUP_INTERRUPT,  /* sinval catchup interrupt */
    PROCSIG_NOTIFY_INTERRUPT,   /* listen/notify interrupt */
    PROCSIG_PARALLEL_MESSAGE,   /* message from cooperating parallel backend */
    PROCSIG_WALSND_INIT_STOPPING,   /* ask walsenders to prepare for shutdown  */

    /* Recovery conflict reasons */
    PROCSIG_RECOVERY_CONFLICT_DATABASE,
    PROCSIG_RECOVERY_CONFLICT_TABLESPACE,
    PROCSIG_RECOVERY_CONFLICT_LOCK,
    PROCSIG_RECOVERY_CONFLICT_SNAPSHOT,
    PROCSIG_RECOVERY_CONFLICT_BUFFERPIN,
    PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK,

    NUM_PROCSIGNALS             /* Must be last! */
} ProcSignalReason;

Function Documentation

procsignal_sigusr1_handler()

void procsignal_sigusr1_handler

(

SIGNAL_ARGS

)

Definition at line 260 of file procsignal.c.

References CheckProcSignal(), HandleCatchupInterrupt(), HandleNotifyInterrupt(), HandleParallelMessageInterrupt(), HandleWalSndInitStopping(), latch_sigusr1_handler(), MyLatch, PROCSIG_CATCHUP_INTERRUPT, PROCSIG_NOTIFY_INTERRUPT, PROCSIG_PARALLEL_MESSAGE, PROCSIG_RECOVERY_CONFLICT_BUFFERPIN, PROCSIG_RECOVERY_CONFLICT_DATABASE, PROCSIG_RECOVERY_CONFLICT_LOCK, PROCSIG_RECOVERY_CONFLICT_SNAPSHOT, PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK, PROCSIG_RECOVERY_CONFLICT_TABLESPACE, PROCSIG_WALSND_INIT_STOPPING, RecoveryConflictInterrupt(), and SetLatch().

Referenced by autoprewarm_main(), AutoVacLauncherMain(), AutoVacWorkerMain(), BackgroundWriterMain(), CheckpointerMain(), PostgresMain(), StartBackgroundWorker(), StartupProcessMain(), WalReceiverMain(), WalSndSignals(), and WalWriterMain().

{
    int         save_errno = errno;

    if (CheckProcSignal(PROCSIG_CATCHUP_INTERRUPT))
        HandleCatchupInterrupt();

    if (CheckProcSignal(PROCSIG_NOTIFY_INTERRUPT))
        HandleNotifyInterrupt();

    if (CheckProcSignal(PROCSIG_PARALLEL_MESSAGE))
        HandleParallelMessageInterrupt();

    if (CheckProcSignal(PROCSIG_WALSND_INIT_STOPPING))
        HandleWalSndInitStopping();

    if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_DATABASE))
        RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_DATABASE);

    if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_TABLESPACE))
        RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_TABLESPACE);

    if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_LOCK))
        RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_LOCK);

    if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT))
        RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT);

    if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK))
        RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);

    if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))
        RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);

    SetLatch(MyLatch);

    latch_sigusr1_handler();

    errno = save_errno;
}

ProcSignalInit()

void ProcSignalInit

(

int

pss_idx

)

Definition at line 104 of file procsignal.c.

References Assert, CleanupProcSignalState(), elog, Int32GetDatum, LOG, MemSet, MyProcPid, NUM_PROCSIGNALS, NumProcSignalSlots, on_shmem_exit(), ProcSignalSlot::pss_pid, and ProcSignalSlot::pss_signalFlags.

Referenced by AuxiliaryProcessMain(), and InitPostgres().

{
    volatile ProcSignalSlot *slot;

    Assert(pss_idx >= 1 && pss_idx <= NumProcSignalSlots);

    slot = &ProcSignalSlots[pss_idx - 1];

    /* sanity check */
    if (slot->pss_pid != 0)
        elog(LOG, "process %d taking over ProcSignal slot %d, but it's not empty",
             MyProcPid, pss_idx);

    /* Clear out any leftover signal reasons */
    MemSet(slot->pss_signalFlags, 0, NUM_PROCSIGNALS * sizeof(sig_atomic_t));

    /* Mark slot with my PID */
    slot->pss_pid = MyProcPid;

    /* Remember slot location for CheckProcSignal */
    MyProcSignalSlot = slot;

    /* Set up to release the slot on process exit */
    on_shmem_exit(CleanupProcSignalState, Int32GetDatum(pss_idx));
}

ProcSignalShmemInit()

void ProcSignalShmemInit

(

void

)

Definition at line 83 of file procsignal.c.

References MemSet, ProcSignalShmemSize(), and ShmemInitStruct().

Referenced by CreateSharedMemoryAndSemaphores().

{
    Size        size = ProcSignalShmemSize();
    bool        found;

    ProcSignalSlots = (ProcSignalSlot *)
        ShmemInitStruct("ProcSignalSlots", size, &found);

    /* If we're first, set everything to zeroes */
    if (!found)
        MemSet(ProcSignalSlots, 0, size);
}

ProcSignalShmemSize()

Size ProcSignalShmemSize

(

void

)

Definition at line 73 of file procsignal.c.

References NumProcSignalSlots.

Referenced by CreateSharedMemoryAndSemaphores(), and ProcSignalShmemInit().

{
    return NumProcSignalSlots * sizeof(ProcSignalSlot);
}

SendProcSignal()

int SendProcSignal	(	pid_t	pid,
		ProcSignalReason	reason,
		BackendId	backendId
	)

Definition at line 179 of file procsignal.c.

References i, InvalidBackendId, kill, NumProcSignalSlots, ProcSignalSlot::pss_pid, ProcSignalSlot::pss_signalFlags, and SIGUSR1.

Referenced by CancelDBBackends(), CancelVirtualTransaction(), mq_putmessage(), ParallelWorkerShutdown(), SICleanupQueue(), SignalBackends(), and WalSndInitStopping().

{
    volatile ProcSignalSlot *slot;

    if (backendId != InvalidBackendId)
    {
        slot = &ProcSignalSlots[backendId - 1];

        /*
         * Note: Since there's no locking, it's possible that the target
         * process detaches from shared memory and exits right after this
         * test, before we set the flag and send signal. And the signal slot
         * might even be recycled by a new process, so it's remotely possible
         * that we set a flag for a wrong process. That's OK, all the signals
         * are such that no harm is done if they're mistakenly fired.
         */
        if (slot->pss_pid == pid)
        {
            /* Atomically set the proper flag */
            slot->pss_signalFlags[reason] = true;
            /* Send signal */
            return kill(pid, SIGUSR1);
        }
    }
    else
    {
        /*
         * BackendId not provided, so search the array using pid.  We search
         * the array back to front so as to reduce search overhead.  Passing
         * InvalidBackendId means that the target is most likely an auxiliary
         * process, which will have a slot near the end of the array.
         */
        int         i;

        for (i = NumProcSignalSlots - 1; i >= 0; i--)
        {
            slot = &ProcSignalSlots[i];

            if (slot->pss_pid == pid)
            {
                /* the above note about race conditions applies here too */

                /* Atomically set the proper flag */
                slot->pss_signalFlags[reason] = true;
                /* Send signal */
                return kill(pid, SIGUSR1);
            }
        }
    }

    errno = ESRCH;
    return -1;
}