pmsignal.c File Reference

#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 "storage/subsystems.h"
#include "utils/memutils.h"

Include dependency graph for pmsignal.c:

Go to the source code of this file.

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	PMSignalShmemRequest (void *)
static void	PMSignalShmemInit (void *)
static void	MarkPostmasterChildInactive (int code, Datum arg)
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
const ShmemCallbacks	PMSignalShmemCallbacks
static int	num_child_flags

Macro Definition Documentation

PM_CHILD_ACTIVE

#define PM_CHILD_ACTIVE   2

Definition at line 69 of file pmsignal.c.

PM_CHILD_ASSIGNED

#define PM_CHILD_ASSIGNED   1

Definition at line 68 of file pmsignal.c.

PM_CHILD_UNUSED

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

Definition at line 67 of file pmsignal.c.

PM_CHILD_WALSENDER

#define PM_CHILD_WALSENDER   3

Definition at line 70 of file pmsignal.c.

Function Documentation

CheckPostmasterSignal()

bool CheckPostmasterSignal

(

PMSignalReason

reason

)

Definition at line 181 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 212 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 fb(), IsUnderPostmaster, PMQUIT_NOT_SENT, PMSignalState, and PMSignalData::sigquit_reason.

Referenced by quickdie().

IsPostmasterChildWalSender()

bool IsPostmasterChildWalSender

(

int

slot

)

Definition at line 270 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 325 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, fb(), 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 229 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 248 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, PMSignalState, and result.

Referenced by ReleasePostmasterChildSlot().

MarkPostmasterChildWalSender()

void MarkPostmasterChildWalSender

(

void

)

Definition at line 308 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, fb(), MyPMChildSlot, num_child_flags, PM_CHILD_ACTIVE, PM_CHILD_WALSENDER, PMSignalData::PMChildFlags, and PMSignalState.

Referenced by InitWalSender().

PMSignalShmemInit()

static void PMSignalShmemInit ( void *  arg )

static

Definition at line 153 of file pmsignal.c.

{
    Assert(PMSignalState);
    Assert(num_child_flags > 0);
    PMSignalState->num_child_flags = num_child_flags;
}

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

PMSignalShmemRequest()

static void PMSignalShmemRequest ( void *  arg )

static

Definition at line 138 of file pmsignal.c.

{
    size_t      size;
 
    num_child_flags = MaxLivePostmasterChildren();
 
    size = add_size(offsetof(PMSignalData, PMChildFlags),
                    mul_size(num_child_flags, sizeof(sig_atomic_t)));
    ShmemRequestStruct(.name = "PMSignalState",
                       .size = size,
                       .ptr = (void **) &PMSignalState,
        );
}

References add_size(), fb(), MaxLivePostmasterChildren(), mul_size(), name, num_child_flags, PMSignalState, and ShmemRequestStruct.

PostmasterDeathSignalInit()

void PostmasterDeathSignalInit

(

void

)

Definition at line 406 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, fb(), and pqsignal.

Referenced by InitPostmasterChild().

PostmasterIsAliveInternal()

bool PostmasterIsAliveInternal

(

void

)

Definition at line 345 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, fb(), postmaster_alive_fds, POSTMASTER_FD_WATCH, and read.

Referenced by WaitEventSetWaitBlock().

RegisterPostmasterChildActive()

void RegisterPostmasterChildActive

(

void

)

Definition at line 289 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, fb(), 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 164 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(), pgaio_worker_request_grow(), RegisterDynamicBackgroundWorker(), RequestXLogStreaming(), SetMultiXactIdLimit(), SetTransactionIdLimit(), TerminateBackgroundWorker(), and TerminateBackgroundWorkersForDatabase().

SetQuitSignalReason()

void SetQuitSignalReason

(

QuitSignalReason

reason

)

Definition at line 201 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

static

Definition at line 100 of file pmsignal.c.

Referenced by IsPostmasterChildWalSender(), MarkPostmasterChildInactive(), MarkPostmasterChildSlotAssigned(), MarkPostmasterChildSlotUnassigned(), MarkPostmasterChildWalSender(), PMSignalShmemInit(), PMSignalShmemRequest(), and RegisterPostmasterChildActive().

PMSignalShmemCallbacks

const ShmemCallbacks PMSignalShmemCallbacks

Initial value:

= {
    .request_fn = PMSignalShmemRequest,
    .init_fn = PMSignalShmemInit,
}

Definition at line 90 of file pmsignal.c.

                                              {
    .request_fn = PMSignalShmemRequest,
    .init_fn = PMSignalShmemInit,
};

PMSignalState

NON_EXEC_STATIC volatile PMSignalData* PMSignalState = NULL

Definition at line 85 of file pmsignal.c.

Referenced by CheckPostmasterSignal(), GetQuitSignalReason(), IsPostmasterChildWalSender(), MarkPostmasterChildInactive(), MarkPostmasterChildSlotAssigned(), MarkPostmasterChildSlotUnassigned(), MarkPostmasterChildWalSender(), PMSignalShmemInit(), PMSignalShmemRequest(), RegisterPostmasterChildActive(), SendPostmasterSignal(), and SetQuitSignalReason().