pmsignal.h File Reference

#include <signal.h>

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Macros
#define	PostmasterIsAlive()   PostmasterIsAliveInternal()

Typedefs
typedef struct PMSignalData	PMSignalData

Enumerations
enum	PMSignalReason {   PMSIGNAL_RECOVERY_STARTED, PMSIGNAL_BEGIN_HOT_STANDBY, PMSIGNAL_WAKEN_ARCHIVER, PMSIGNAL_ROTATE_LOGFILE,   PMSIGNAL_START_AUTOVAC_LAUNCHER, PMSIGNAL_START_AUTOVAC_WORKER, PMSIGNAL_BACKGROUND_WORKER_CHANGE, PMSIGNAL_START_WALRECEIVER,   PMSIGNAL_ADVANCE_STATE_MACHINE, NUM_PMSIGNALS }

Functions
Size	PMSignalShmemSize (void)
void	PMSignalShmemInit (void)
void	SendPostmasterSignal (PMSignalReason reason)
bool	CheckPostmasterSignal (PMSignalReason reason)
int	AssignPostmasterChildSlot (void)
bool	ReleasePostmasterChildSlot (int slot)
bool	IsPostmasterChildWalSender (int slot)
void	MarkPostmasterChildActive (void)
void	MarkPostmasterChildInactive (void)
void	MarkPostmasterChildWalSender (void)
bool	PostmasterIsAliveInternal (void)
void	PostmasterDeathSignalInit (void)

Macro Definition Documentation

PostmasterIsAlive

#define PostmasterIsAlive

(

)

PostmasterIsAliveInternal()

Definition at line 91 of file pmsignal.h.

Referenced by HandleStartupProcInterrupts(), and pgarch_ArchiverCopyLoop().

Typedef Documentation

PMSignalData

typedef struct PMSignalData PMSignalData

Definition at line 49 of file pmsignal.h.

Enumeration Type Documentation

PMSignalReason

enum PMSignalReason

Enumerator
PMSIGNAL_RECOVERY_STARTED
PMSIGNAL_BEGIN_HOT_STANDBY
PMSIGNAL_WAKEN_ARCHIVER
PMSIGNAL_ROTATE_LOGFILE
PMSIGNAL_START_AUTOVAC_LAUNCHER
PMSIGNAL_START_AUTOVAC_WORKER
PMSIGNAL_BACKGROUND_WORKER_CHANGE
PMSIGNAL_START_WALRECEIVER
PMSIGNAL_ADVANCE_STATE_MACHINE
NUM_PMSIGNALS

Definition at line 33 of file pmsignal.h.

{
    PMSIGNAL_RECOVERY_STARTED,  /* recovery has started */
    PMSIGNAL_BEGIN_HOT_STANDBY, /* begin Hot Standby */
    PMSIGNAL_WAKEN_ARCHIVER,    /* send a NOTIFY signal to xlog archiver */
    PMSIGNAL_ROTATE_LOGFILE,    /* send SIGUSR1 to syslogger to rotate logfile */
    PMSIGNAL_START_AUTOVAC_LAUNCHER,    /* start an autovacuum launcher */
    PMSIGNAL_START_AUTOVAC_WORKER,  /* start an autovacuum worker */
    PMSIGNAL_BACKGROUND_WORKER_CHANGE,  /* background worker state change */
    PMSIGNAL_START_WALRECEIVER, /* start a walreceiver */
    PMSIGNAL_ADVANCE_STATE_MACHINE, /* advance postmaster's state machine */

    NUM_PMSIGNALS               /* Must be last value of enum! */
} PMSignalReason;

Function Documentation

AssignPostmasterChildSlot()

int AssignPostmasterChildSlot

(

void

)

Definition at line 184 of file pmsignal.c.

References elog, FATAL, PMSignalData::next_child_flag, PMSignalData::num_child_flags, PM_CHILD_ASSIGNED, PM_CHILD_UNUSED, PMSignalData::PMChildFlags, and PMSignalState.

Referenced by assign_backendlist_entry(), BackendStartup(), and StartAutovacuumWorker().

{
    int         slot = PMSignalState->next_child_flag;
    int         n;

    /*
     * Scan for a free slot.  We track the last slot assigned so as not to
     * waste time repeatedly rescanning low-numbered slots.
     */
    for (n = PMSignalState->num_child_flags; n > 0; n--)
    {
        if (--slot < 0)
            slot = PMSignalState->num_child_flags - 1;
        if (PMSignalState->PMChildFlags[slot] == PM_CHILD_UNUSED)
        {
            PMSignalState->PMChildFlags[slot] = PM_CHILD_ASSIGNED;
            PMSignalState->next_child_flag = slot;
            return slot + 1;
        }
    }

    /* Out of slots ... should never happen, else postmaster.c messed up */
    elog(FATAL, "no free slots in PMChildFlags array");
    return 0;                   /* keep compiler quiet */
}

CheckPostmasterSignal()

bool CheckPostmasterSignal

(

PMSignalReason

reason

)

Definition at line 163 of file pmsignal.c.

References PMSignalData::PMSignalFlags, and PMSignalState.

Referenced by sigusr1_handler().

{
    /* Careful here --- don't clear flag if we haven't seen it set */
    if (PMSignalState->PMSignalFlags[reason])
    {
        PMSignalState->PMSignalFlags[reason] = false;
        return true;
    }
    return false;
}

IsPostmasterChildWalSender()

bool IsPostmasterChildWalSender

(

int

slot

)

Definition at line 240 of file pmsignal.c.

References Assert, PMSignalData::num_child_flags, PM_CHILD_WALSENDER, PMSignalData::PMChildFlags, and PMSignalState.

Referenced by CountChildren(), and SignalSomeChildren().

{
    Assert(slot > 0 && slot <= PMSignalState->num_child_flags);
    slot--;

    if (PMSignalState->PMChildFlags[slot] == PM_CHILD_WALSENDER)
        return true;
    else
        return false;
}

MarkPostmasterChildActive()

void MarkPostmasterChildActive

(

void

)

Definition at line 256 of file pmsignal.c.

References Assert, MyPMChildSlot, PMSignalData::num_child_flags, PM_CHILD_ACTIVE, PM_CHILD_ASSIGNED, PMSignalData::PMChildFlags, and PMSignalState.

Referenced by InitProcess().

{
    int         slot = MyPMChildSlot;

    Assert(slot > 0 && slot <= PMSignalState->num_child_flags);
    slot--;
    Assert(PMSignalState->PMChildFlags[slot] == PM_CHILD_ASSIGNED);
    PMSignalState->PMChildFlags[slot] = PM_CHILD_ACTIVE;
}

MarkPostmasterChildInactive()

void MarkPostmasterChildInactive

(

void

)

Definition at line 289 of file pmsignal.c.

References Assert, MyPMChildSlot, PMSignalData::num_child_flags, PM_CHILD_ACTIVE, PM_CHILD_ASSIGNED, PM_CHILD_WALSENDER, PMSignalData::PMChildFlags, and PMSignalState.

Referenced by ProcKill().

{
    int         slot = MyPMChildSlot;

    Assert(slot > 0 && slot <= PMSignalState->num_child_flags);
    slot--;
    Assert(PMSignalState->PMChildFlags[slot] == PM_CHILD_ACTIVE ||
           PMSignalState->PMChildFlags[slot] == PM_CHILD_WALSENDER);
    PMSignalState->PMChildFlags[slot] = PM_CHILD_ASSIGNED;
}

MarkPostmasterChildWalSender()

void MarkPostmasterChildWalSender

(

void

)

Definition at line 272 of file pmsignal.c.

References am_walsender, Assert, MyPMChildSlot, PMSignalData::num_child_flags, PM_CHILD_ACTIVE, PM_CHILD_WALSENDER, PMSignalData::PMChildFlags, and PMSignalState.

{
    int         slot = MyPMChildSlot;

    Assert(am_walsender);

    Assert(slot > 0 && slot <= PMSignalState->num_child_flags);
    slot--;
    Assert(PMSignalState->PMChildFlags[slot] == PM_CHILD_ACTIVE);
    PMSignalState->PMChildFlags[slot] = PM_CHILD_WALSENDER;
}

PMSignalShmemInit()

void PMSignalShmemInit

(

void

)

Definition at line 128 of file pmsignal.c.

References MaxLivePostmasterChildren(), MemSet, PMSignalData::num_child_flags, PMSignalShmemSize(), PMSignalState, ShmemInitStruct(), and unvolatize.

Referenced by CreateSharedMemoryAndSemaphores().

{
    bool        found;

    PMSignalState = (PMSignalData *)
        ShmemInitStruct("PMSignalState", PMSignalShmemSize(), &found);

    if (!found)
    {
        MemSet(unvolatize(PMSignalData *, PMSignalState), 0, PMSignalShmemSize());
        PMSignalState->num_child_flags = MaxLivePostmasterChildren();
    }
}

PMSignalShmemSize()

Size PMSignalShmemSize

(

void

)

Definition at line 113 of file pmsignal.c.

References add_size(), MaxLivePostmasterChildren(), mul_size(), offsetof, and PMSignalData::PMChildFlags.

Referenced by CreateSharedMemoryAndSemaphores(), and PMSignalShmemInit().

{
    Size        size;

    size = offsetof(PMSignalData, PMChildFlags);
    size = add_size(size, mul_size(MaxLivePostmasterChildren(),
                                   sizeof(sig_atomic_t)));

    return size;
}

PostmasterDeathSignalInit()

void PostmasterDeathSignalInit

(

void

)

Definition at line 370 of file pmsignal.c.

References elog, ERROR, and pqsignal().

Referenced by InitPostmasterChild().

{
#ifdef USE_POSTMASTER_DEATH_SIGNAL
    int         signum = POSTMASTER_DEATH_SIGNAL;

    /* Register our signal handler. */
    pqsignal(signum, postmaster_death_handler);

    /* Request a signal on parent exit. */
#if defined(PR_SET_PDEATHSIG)
    if (prctl(PR_SET_PDEATHSIG, signum) < 0)
        elog(ERROR, "could not request parent death signal: %m");
#elif defined(PROC_PDEATHSIG_CTL)
    if (procctl(P_PID, 0, PROC_PDEATHSIG_CTL, &signum) < 0)
        elog(ERROR, "could not request parent death signal: %m");
#else
#error "USE_POSTMASTER_DEATH_SIGNAL set, but there is no mechanism to request the signal"
#endif

    /*
     * Just in case the parent was gone already and we missed it, we'd better
     * check the slow way on the first call.
     */
    postmaster_possibly_dead = true;
#endif                          /* USE_POSTMASTER_DEATH_SIGNAL */
}

PostmasterIsAliveInternal()

bool PostmasterIsAliveInternal

(

void

)

Definition at line 309 of file pmsignal.c.

References EAGAIN, elog, EWOULDBLOCK, FATAL, postmaster_alive_fds, POSTMASTER_FD_WATCH, and read.

Referenced by WaitEventSetWait().

{
#ifdef USE_POSTMASTER_DEATH_SIGNAL
    /*
     * Reset the flag before checking, so that we don't miss a signal if
     * postmaster dies right after the check.  If postmaster was indeed dead,
     * we'll re-arm it before returning to caller.
     */
    postmaster_possibly_dead = false;
#endif

#ifndef WIN32
    {
        char        c;
        ssize_t     rc;

        rc = read(postmaster_alive_fds[POSTMASTER_FD_WATCH], &c, 1);

        /*
         * In the usual case, the postmaster is still alive, and there is no
         * data in the pipe.
         */
        if (rc < 0 && (errno == EAGAIN || errno == EWOULDBLOCK))
            return true;
        else
        {
            /*
             * Postmaster is dead, or something went wrong with the read()
             * call.
             */

#ifdef USE_POSTMASTER_DEATH_SIGNAL
            postmaster_possibly_dead = true;
#endif

            if (rc < 0)
                elog(FATAL, "read on postmaster death monitoring pipe failed: %m");
            else if (rc > 0)
                elog(FATAL, "unexpected data in postmaster death monitoring pipe");

            return false;
        }
    }

#else                           /* WIN32 */
    if (WaitForSingleObject(PostmasterHandle, 0) == WAIT_TIMEOUT)
        return true;
    else
    {
#ifdef USE_POSTMASTER_DEATH_SIGNAL
        postmaster_possibly_dead = true;
#endif
        return false;
    }
#endif                          /* WIN32 */
}

ReleasePostmasterChildSlot()

bool ReleasePostmasterChildSlot

(

int

slot

)

Definition at line 218 of file pmsignal.c.

References Assert, PMSignalData::num_child_flags, PM_CHILD_ASSIGNED, PM_CHILD_UNUSED, PMSignalData::PMChildFlags, and PMSignalState.

Referenced by BackendStartup(), CleanupBackend(), CleanupBackgroundWorker(), do_start_bgworker(), HandleChildCrash(), and StartAutovacuumWorker().

{
    bool        result;

    Assert(slot > 0 && slot <= PMSignalState->num_child_flags);
    slot--;

    /*
     * Note: the slot state might already be unused, because the logic in
     * postmaster.c is such that this might get called twice when a child
     * crashes.  So we don't try to Assert anything about the state.
     */
    result = (PMSignalState->PMChildFlags[slot] == PM_CHILD_ASSIGNED);
    PMSignalState->PMChildFlags[slot] = PM_CHILD_UNUSED;
    return result;
}

SendPostmasterSignal()

void SendPostmasterSignal

(

PMSignalReason

reason

)

Definition at line 146 of file pmsignal.c.

References IsUnderPostmaster, kill, PMSignalData::PMSignalFlags, PMSignalState, PostmasterPid, and SIGUSR1.

Referenced by AutoVacLauncherMain(), CheckRecoveryConsistency(), do_start_worker(), GetNewMultiXactId(), GetNewTransactionId(), pg_rotate_logfile(), pg_rotate_logfile_v2(), RegisterDynamicBackgroundWorker(), RequestXLogStreaming(), SetMultiXactIdLimit(), SetTransactionIdLimit(), StartupXLOG(), TerminateBackgroundWorker(), and XLogArchiveNotify().

{
    /* If called in a standalone backend, do nothing */
    if (!IsUnderPostmaster)
        return;
    /* Atomically set the proper flag */
    PMSignalState->PMSignalFlags[reason] = true;
    /* Send signal to postmaster */
    kill(PostmasterPid, SIGUSR1);
}