#include "postgres.h"
#include <signal.h>
#include <unistd.h>
#include "miscadmin.h"
#include "postmaster/postmaster.h"
#include "replication/walsender.h"
#include "storage/ipc.h"
#include "storage/pmsignal.h"
#include "storage/shmem.h"
#include "utils/memutils.h"

Include dependency graph for pmsignal.c:

Data Structures
struct	PMSignalData

Macros
#define	PM_CHILD_UNUSED 0 /* these values must fit in sig_atomic_t */

#define	PM_CHILD_ASSIGNED 1

#define	PM_CHILD_ACTIVE 2

#define	PM_CHILD_WALSENDER 3

Functions
static void	MarkPostmasterChildInactive (int code, Datum arg)

Size	PMSignalShmemSize (void)

void	PMSignalShmemInit (void)

void	SendPostmasterSignal (PMSignalReason reason)

bool	CheckPostmasterSignal (PMSignalReason reason)

void	SetQuitSignalReason (QuitSignalReason reason)

QuitSignalReason	GetQuitSignalReason (void)

void	MarkPostmasterChildSlotAssigned (int slot)

bool	MarkPostmasterChildSlotUnassigned (int slot)

bool	IsPostmasterChildWalSender (int slot)

void	RegisterPostmasterChildActive (void)

void	MarkPostmasterChildWalSender (void)

bool	PostmasterIsAliveInternal (void)

void	PostmasterDeathSignalInit (void)

Variables
NON_EXEC_STATIC volatile PMSignalData *	PMSignalState = NULL

static int	num_child_flags

Macro Definition Documentation

◆ PM_CHILD_ACTIVE

#define PM_CHILD_ACTIVE 2

Definition at line 68 of file pmsignal.c.

◆ PM_CHILD_ASSIGNED

#define PM_CHILD_ASSIGNED 1

Definition at line 67 of file pmsignal.c.

◆ PM_CHILD_UNUSED

#define PM_CHILD_UNUSED 0 /* these values must fit in sig_atomic_t */

Definition at line 66 of file pmsignal.c.

◆ PM_CHILD_WALSENDER

#define PM_CHILD_WALSENDER 3

Definition at line 69 of file pmsignal.c.

Function Documentation

◆ CheckPostmasterSignal()

bool CheckPostmasterSignal ( PMSignalReason reason )

Definition at line 182 of file pmsignal.c.

{
    /* 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;
}

References PMSignalData::PMSignalFlags, and PMSignalState.

Referenced by process_pm_pmsignal().

◆ GetQuitSignalReason()

QuitSignalReason GetQuitSignalReason ( void )

Definition at line 213 of file pmsignal.c.

{
    /* This is called in signal handlers, so be extra paranoid. */
    if (!IsUnderPostmaster || PMSignalState == NULL)
        return PMQUIT_NOT_SENT;
    return PMSignalState->sigquit_reason;
}

References IsUnderPostmaster, PMQUIT_NOT_SENT, PMSignalState, and PMSignalData::sigquit_reason.

Referenced by quickdie().

◆ IsPostmasterChildWalSender()

bool IsPostmasterChildWalSender ( int slot )

Definition at line 271 of file pmsignal.c.

{
    Assert(slot > 0 && slot <= num_child_flags);
    slot--;
 
    if (PMSignalState->PMChildFlags[slot] == PM_CHILD_WALSENDER)
        return true;
    else
        return false;
}

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

Referenced by CountChildren(), and SignalChildren().

◆ MarkPostmasterChildInactive()

static void MarkPostmasterChildInactive	(	int	code,
		Datum	arg
	)

static

Definition at line 326 of file pmsignal.c.

{
    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;
}

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

Referenced by RegisterPostmasterChildActive().

◆ MarkPostmasterChildSlotAssigned()

void MarkPostmasterChildSlotAssigned ( int slot )

Definition at line 230 of file pmsignal.c.

{
    Assert(slot > 0 && slot <= num_child_flags);
    slot--;
 
    if (PMSignalState->PMChildFlags[slot] != PM_CHILD_UNUSED)
        elog(FATAL, "postmaster child slot is already in use");
 
    PMSignalState->PMChildFlags[slot] = PM_CHILD_ASSIGNED;
}

References Assert(), elog, FATAL, num_child_flags, PM_CHILD_ASSIGNED, PM_CHILD_UNUSED, PMSignalData::PMChildFlags, and PMSignalState.

Referenced by AssignPostmasterChildSlot().

◆ MarkPostmasterChildSlotUnassigned()

bool MarkPostmasterChildSlotUnassigned ( int slot )

Definition at line 249 of file pmsignal.c.

{
    bool        result;
 
    Assert(slot > 0 && slot <= 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;
}

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

Referenced by ReleasePostmasterChildSlot().

◆ MarkPostmasterChildWalSender()

void MarkPostmasterChildWalSender ( void )

Definition at line 309 of file pmsignal.c.

{
    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;
}

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

Referenced by InitWalSender().

◆ PMSignalShmemInit()

void PMSignalShmemInit ( void )

Definition at line 145 of file pmsignal.c.

{
    bool        found;
 
    PMSignalState = (PMSignalData *)
        ShmemInitStruct("PMSignalState", PMSignalShmemSize(), &found);
 
    if (!found)
    {
        /* initialize all flags to zeroes */
        MemSet(unvolatize(PMSignalData *, PMSignalState), 0, PMSignalShmemSize());
        num_child_flags = MaxLivePostmasterChildren();
        PMSignalState->num_child_flags = num_child_flags;
    }
}

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

Referenced by CreateOrAttachShmemStructs().

◆ PMSignalShmemSize()

Size PMSignalShmemSize ( void )

Definition at line 130 of file pmsignal.c.

{
    Size        size;
 
    size = offsetof(PMSignalData, PMChildFlags);
    size = add_size(size, mul_size(MaxLivePostmasterChildren(),
                                   sizeof(sig_atomic_t)));
 
    return size;
}

References add_size(), MaxLivePostmasterChildren(), and mul_size().

Referenced by CalculateShmemSize(), and PMSignalShmemInit().

◆ PostmasterDeathSignalInit()

void PostmasterDeathSignalInit ( void )

Definition at line 407 of file pmsignal.c.

{
#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 */
}

References elog, ERROR, and pqsignal.

Referenced by InitPostmasterChild().

◆ PostmasterIsAliveInternal()

bool PostmasterIsAliveInternal ( void )

Definition at line 346 of file pmsignal.c.

{
#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 */
}

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

Referenced by WaitEventSetWaitBlock().

◆ RegisterPostmasterChildActive()

void RegisterPostmasterChildActive ( void )

Definition at line 290 of file pmsignal.c.

{
    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;
 
    /* Arrange to clean up at exit. */
    on_shmem_exit(MarkPostmasterChildInactive, 0);
}

References Assert(), MarkPostmasterChildInactive(), MyPMChildSlot, num_child_flags, on_shmem_exit(), PM_CHILD_ACTIVE, PM_CHILD_ASSIGNED, PMSignalData::PMChildFlags, and PMSignalState.

Referenced by InitAuxiliaryProcess(), and InitProcess().

◆ SendPostmasterSignal()

void SendPostmasterSignal ( PMSignalReason reason )

Definition at line 165 of file pmsignal.c.

{
    /* 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);
}

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

Referenced by AutoVacLauncherMain(), CheckpointerMain(), CheckRecoveryConsistency(), do_start_worker(), GetNewMultiXactId(), GetNewTransactionId(), InitWalSender(), PerformWalRecovery(), pg_rotate_logfile(), RegisterDynamicBackgroundWorker(), RequestXLogStreaming(), SetMultiXactIdLimit(), SetTransactionIdLimit(), and TerminateBackgroundWorker().

◆ SetQuitSignalReason()

void SetQuitSignalReason ( QuitSignalReason reason )

Definition at line 202 of file pmsignal.c.

{
    PMSignalState->sigquit_reason = reason;
}

References PMSignalState, and PMSignalData::sigquit_reason.

Referenced by HandleFatalError(), and process_pm_shutdown_request().

Variable Documentation

◆ num_child_flags

int num_child_flags