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/*-------------------------------------------------------------------------
* auxprocess.c
* functions related to auxiliary processes.
*
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/postmaster/auxprocess.c
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <unistd.h>
#include <signal.h>
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/auxprocess.h"
#include "postmaster/bgwriter.h"
#include "postmaster/startup.h"
#include "postmaster/walwriter.h"
#include "replication/walreceiver.h"
#include "storage/bufmgr.h"
#include "storage/bufpage.h"
#include "storage/condition_variable.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "tcop/tcopprot.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
#include "utils/rel.h"
static void ShutdownAuxiliaryProcess(int code, Datum arg);
/* ----------------
* global variables
* ----------------
*/
AuxProcType MyAuxProcType = NotAnAuxProcess; /* declared in miscadmin.h */
/*
* AuxiliaryProcessMain
*
* The main entry point for auxiliary processes, such as the bgwriter,
* walwriter, walreceiver, bootstrapper and the shared memory checker code.
*
* This code is here just because of historical reasons.
*/
void
AuxiliaryProcessMain(AuxProcType auxtype)
{
Assert(IsUnderPostmaster);
MyAuxProcType = auxtype;
switch (MyAuxProcType)
{
case StartupProcess:
MyBackendType = B_STARTUP;
break;
case ArchiverProcess:
MyBackendType = B_ARCHIVER;
break;
case BgWriterProcess:
MyBackendType = B_BG_WRITER;
break;
case CheckpointerProcess:
MyBackendType = B_CHECKPOINTER;
break;
case WalWriterProcess:
MyBackendType = B_WAL_WRITER;
break;
case WalReceiverProcess:
MyBackendType = B_WAL_RECEIVER;
break;
default:
elog(ERROR, "something has gone wrong");
MyBackendType = B_INVALID;
}
init_ps_display(NULL);
SetProcessingMode(BootstrapProcessing);
IgnoreSystemIndexes = true;
/*
* As an auxiliary process, we aren't going to do the full InitPostgres
* pushups, but there are a couple of things that need to get lit up even
* in an auxiliary process.
*/
/*
* Create a PGPROC so we can use LWLocks. In the EXEC_BACKEND case, this
* was already done by SubPostmasterMain().
*/
#ifndef EXEC_BACKEND
InitAuxiliaryProcess();
#endif
BaseInit();
/*
* Assign the ProcSignalSlot for an auxiliary process. Since it doesn't
* have a BackendId, the slot is statically allocated based on the
* auxiliary process type (MyAuxProcType). Backends use slots indexed in
* the range from 1 to MaxBackends (inclusive), so we use MaxBackends +
* AuxProcType + 1 as the index of the slot for an auxiliary process.
*
* This will need rethinking if we ever want more than one of a particular
* auxiliary process type.
*/
ProcSignalInit(MaxBackends + MyAuxProcType + 1);
/*
* Auxiliary processes don't run transactions, but they may need a
* resource owner anyway to manage buffer pins acquired outside
* transactions (and, perhaps, other things in future).
*/
CreateAuxProcessResourceOwner();
/* Initialize backend status information */
pgstat_beinit();
pgstat_bestart();
/* register a before-shutdown callback for LWLock cleanup */
before_shmem_exit(ShutdownAuxiliaryProcess, 0);
SetProcessingMode(NormalProcessing);
switch (MyAuxProcType)
{
case StartupProcess:
StartupProcessMain();
proc_exit(1);
case ArchiverProcess:
PgArchiverMain();
proc_exit(1);
case BgWriterProcess:
BackgroundWriterMain();
proc_exit(1);
case CheckpointerProcess:
CheckpointerMain();
proc_exit(1);
case WalWriterProcess:
WalWriterMain();
proc_exit(1);
case WalReceiverProcess:
WalReceiverMain();
proc_exit(1);
default:
elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
proc_exit(1);
}
}
/*
* Begin shutdown of an auxiliary process. This is approximately the equivalent
* of ShutdownPostgres() in postinit.c. We can't run transactions in an
* auxiliary process, so most of the work of AbortTransaction() is not needed,
* but we do need to make sure we've released any LWLocks we are holding.
* (This is only critical during an error exit.)
*/
static void
ShutdownAuxiliaryProcess(int code, Datum arg)
{
LWLockReleaseAll();
ConditionVariableCancelSleep();
pgstat_report_wait_end();
}
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