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Create an internal semaphore API that is not tied to SysV semaphores.

Browse Source 
As proof of concept, provide an alternate implementation based on POSIX
semaphores.  Also push the SysV shared-memory implementation into a
separate file so that it can be replaced conveniently.
This commit is contained in:
Tom Lane 2002-05-05 00:03:29 +00:00
parent 91fc10fdac
commit 72a3902a66
37 changed files with 1659 additions and 1370 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
configure vendored
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@ -15664,6 +15664,42 @@ HAVE_POSIX_SIGNALS=$pgac_cv_func_posix_signals
# Select semaphore implementation type.
if test x"$USE_NAMED_POSIX_SEMAPHORES" = x"1" ; then
cat >>confdefs.h <<\_ACEOF
#define USE_NAMED_POSIX_SEMAPHORES 1
_ACEOF
SEMA_IMPLEMENTATION="src/backend/port/posix_sema.c"
else
if test x"$USE_UNNAMED_POSIX_SEMAPHORES" = x"1" ; then
cat >>confdefs.h <<\_ACEOF
#define USE_UNNAMED_POSIX_SEMAPHORES 1
_ACEOF
SEMA_IMPLEMENTATION="src/backend/port/posix_sema.c"
else
cat >>confdefs.h <<\_ACEOF
#define USE_SYSV_SEMAPHORES 1
_ACEOF
SEMA_IMPLEMENTATION="src/backend/port/sysv_sema.c"
fi
fi
# Select shared-memory implementation type.
cat >>confdefs.h <<\_ACEOF
#define USE_SYSV_SHARED_MEMORY 1
_ACEOF
SHMEM_IMPLEMENTATION="src/backend/port/sysv_shmem.c"
if test "$enable_nls" = yes ; then
echo "$as_me:$LINENO: checking for library containing gettext" >&5
@ -16724,7 +16760,7 @@ fi
ac_config_files="$ac_config_files GNUmakefile src/Makefile.global"
ac_config_links="$ac_config_links src/backend/port/dynloader.c:src/backend/port/dynloader/${template}.c src/include/dynloader.h:src/backend/port/dynloader/${template}.h src/include/pg_config_os.h:src/include/port/${template}.h src/Makefile.port:src/makefiles/Makefile.${template}"
ac_config_links="$ac_config_links src/backend/port/dynloader.c:src/backend/port/dynloader/${template}.c src/backend/port/pg_sema.c:${SEMA_IMPLEMENTATION} src/backend/port/pg_shmem.c:${SHMEM_IMPLEMENTATION} src/include/dynloader.h:src/backend/port/dynloader/${template}.h src/include/pg_config_os.h:src/include/port/${template}.h src/Makefile.port:src/makefiles/Makefile.${template}"
ac_config_headers="$ac_config_headers src/include/pg_config.h"
@ -17207,6 +17243,8 @@ do
"src/Makefile.global" ) CONFIG_FILES="$CONFIG_FILES src/Makefile.global" ;;
"src/backend/port/tas.s" ) CONFIG_LINKS="$CONFIG_LINKS src/backend/port/tas.s:src/backend/port/tas/${tas_file}" ;;
"src/backend/port/dynloader.c" ) CONFIG_LINKS="$CONFIG_LINKS src/backend/port/dynloader.c:src/backend/port/dynloader/${template}.c" ;;
"src/backend/port/pg_sema.c" ) CONFIG_LINKS="$CONFIG_LINKS src/backend/port/pg_sema.c:${SEMA_IMPLEMENTATION}" ;;
"src/backend/port/pg_shmem.c" ) CONFIG_LINKS="$CONFIG_LINKS src/backend/port/pg_shmem.c:${SHMEM_IMPLEMENTATION}" ;;
"src/include/dynloader.h" ) CONFIG_LINKS="$CONFIG_LINKS src/include/dynloader.h:src/backend/port/dynloader/${template}.h" ;;
"src/include/pg_config_os.h" ) CONFIG_LINKS="$CONFIG_LINKS src/include/pg_config_os.h:src/include/port/${template}.h" ;;
"src/Makefile.port" ) CONFIG_LINKS="$CONFIG_LINKS src/Makefile.port:src/makefiles/Makefile.${template}" ;;

24
configure.in
View File

@ -1,5 +1,5 @@
dnl Process this file with autoconf to produce a configure script.
dnl $Header: /cvsroot/pgsql/configure.in,v 1.183 2002/04/26 19:47:35 tgl Exp $
dnl $Header: /cvsroot/pgsql/configure.in,v 1.184 2002/05/05 00:03:28 tgl Exp $
dnl Developers, please strive to achieve this order:
dnl
@ -1168,6 +1168,26 @@ AC_CHECK_TYPES([sig_atomic_t], [], [], [#include <signal.h>])
PGAC_FUNC_POSIX_SIGNALS
# Select semaphore implementation type.
if test x"$USE_NAMED_POSIX_SEMAPHORES" = x"1" ; then
AC_DEFINE(USE_NAMED_POSIX_SEMAPHORES, 1, [Define to select named POSIX semaphores])
SEMA_IMPLEMENTATION="src/backend/port/posix_sema.c"
else
if test x"$USE_UNNAMED_POSIX_SEMAPHORES" = x"1" ; then
AC_DEFINE(USE_UNNAMED_POSIX_SEMAPHORES, 1, [Define to select unnamed POSIX semaphores])
SEMA_IMPLEMENTATION="src/backend/port/posix_sema.c"
else
AC_DEFINE(USE_SYSV_SEMAPHORES, 1, [Define to select SysV-style semaphores])
SEMA_IMPLEMENTATION="src/backend/port/sysv_sema.c"
fi
fi
# Select shared-memory implementation type.
AC_DEFINE(USE_SYSV_SHARED_MEMORY, 1, [Define to select SysV-style shared memory])
SHMEM_IMPLEMENTATION="src/backend/port/sysv_shmem.c"
if test "$enable_nls" = yes ; then
PGAC_CHECK_GETTEXT
fi
@ -1222,6 +1242,8 @@ AC_CONFIG_FILES([GNUmakefile src/Makefile.global])
AC_CONFIG_LINKS([
src/backend/port/dynloader.c:src/backend/port/dynloader/${template}.c
src/backend/port/pg_sema.c:${SEMA_IMPLEMENTATION}
src/backend/port/pg_shmem.c:${SHMEM_IMPLEMENTATION}
src/include/dynloader.h:src/backend/port/dynloader/${template}.h
src/include/pg_config_os.h:src/include/port/${template}.h
src/Makefile.port:src/makefiles/Makefile.${template}

4
src/backend/Makefile
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@ -4,7 +4,7 @@
#
# Copyright (c) 1994, Regents of the University of California
#
# $Header: /cvsroot/pgsql/src/backend/Makefile,v 1.77 2002/03/13 00:05:05 petere Exp $
# $Header: /cvsroot/pgsql/src/backend/Makefile,v 1.78 2002/05/05 00:03:28 tgl Exp $
#
#-------------------------------------------------------------------------
@ -194,7 +194,7 @@ ifeq ($(enable_nls), yes)
endif
distclean: clean
rm -f port/tas.s port/dynloader.c
rm -f port/tas.s port/dynloader.c port/pg_sema.c port/pg_shmem.c
maintainer-clean: distclean
rm -f $(srcdir)/bootstrap/bootparse.c \

3
src/backend/bootstrap/bootstrap.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.127 2002/04/27 21:24:33 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.128 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -33,6 +33,7 @@
#include "catalog/pg_type.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"

3
src/backend/catalog/namespace.c
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@ -13,7 +13,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/namespace.c,v 1.17 2002/05/01 23:06:41 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/namespace.c,v 1.18 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -36,6 +36,7 @@
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "storage/backendid.h"
#include "storage/ipc.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/catcache.h"

3
src/backend/commands/async.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.83 2002/03/06 06:09:29 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.84 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -85,6 +85,7 @@
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "storage/ipc.h"
#include "tcop/tcopprot.h"
#include "utils/fmgroids.h"
#include "utils/ps_status.h"

5
src/backend/libpq/auth.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/libpq/auth.c,v 1.80 2002/04/04 04:25:47 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/libpq/auth.c,v 1.81 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -25,6 +25,7 @@
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#include "libpq/auth.h"
#include "libpq/crypt.h"
#include "libpq/hba.h"
@ -32,6 +33,8 @@
#include "libpq/password.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "storage/ipc.h"
static void sendAuthRequest(Port *port, AuthRequest areq);
static int old_be_recvauth(Port *port);

3
src/backend/libpq/pqcomm.c
View File

@ -29,7 +29,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: pqcomm.c,v 1.132 2002/04/21 01:03:33 tgl Exp $
* $Id: pqcomm.c,v 1.133 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -79,6 +79,7 @@
#include "libpq/libpq.h"
#include "miscadmin.h"
#include "storage/ipc.h"
static void pq_close(void);

4
src/backend/port/Makefile
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@ -13,7 +13,7 @@
# be converted to Method 2.
#
# IDENTIFICATION
# $Header: /cvsroot/pgsql/src/backend/port/Makefile,v 1.11 2002/03/13 00:05:06 petere Exp $
# $Header: /cvsroot/pgsql/src/backend/port/Makefile,v 1.12 2002/05/05 00:03:28 tgl Exp $
#
#-------------------------------------------------------------------------
@ -21,7 +21,7 @@ subdir = src/backend/port
top_builddir = ../../..
include $(top_builddir)/src/Makefile.global
OBJS = dynloader.o
OBJS = dynloader.o pg_sema.o pg_shmem.o
OBJS += $(GETHOSTNAME) $(GETRUSAGE) $(INET_ATON) $(ISINF) $(MEMCMP) \
$(MISSING_RANDOM) $(SNPRINTF) $(SRANDOM) $(STRCASECMP) $(STRERROR) \

357
src/backend/port/posix_sema.c Normal file
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@ -0,0 +1,357 @@
/*-------------------------------------------------------------------------
*
* posix_sema.c
* Implement PGSemaphores using POSIX semaphore facilities
*
* We prefer the unnamed style of POSIX semaphore (the kind made with
* sem_init). We can cope with the kind made with sem_open, however.
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/port/posix_sema.c,v 1.1 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include "storage/pg_sema.h"
#ifdef USE_NAMED_POSIX_SEMAPHORES
/* PGSemaphore is pointer to pointer to sem_t */
#define PG_SEM_REF(x) (*(x))
#else
/* PGSemaphore is pointer to sem_t */
#define PG_SEM_REF(x) (x)
#endif
#define IPCProtection (0600) /* access/modify by user only */
static sem_t **mySemPointers; /* keep track of created semaphores */
static int numSems; /* number of semas acquired so far */
static int maxSems; /* allocated size of mySemaPointers array */
static int nextSemKey; /* next name to try */
static void ReleaseSemaphores(int status, Datum arg);
#ifdef USE_NAMED_POSIX_SEMAPHORES
/*
* PosixSemaphoreCreate
*
* Attempt to create a new named semaphore.
*
* If we fail with a failure code other than collision-with-existing-sema,
* print out an error and abort. Other types of errors suggest nonrecoverable
* problems.
*/
static sem_t *
PosixSemaphoreCreate(void)
{
int semKey;
char semname[64];
sem_t *mySem;
for (;;)
{
semKey = nextSemKey++;
snprintf(semname, sizeof(semname), "/pgsql-%d", semKey);
mySem = sem_open(semname, O_CREAT | O_EXCL,
(mode_t) IPCProtection, (unsigned) 1);
if (mySem != SEM_FAILED)
break;
/* Loop if error indicates a collision */
if (errno == EEXIST || errno == EACCES || errno == EINTR)
continue;
/*
* Else complain and abort
*/
fprintf(stderr, "PosixSemaphoreCreate: sem_open(%s) failed: %s\n",
semname, strerror(errno));
proc_exit(1);
}
/*
* Unlink the semaphore immediately, so it can't be accessed externally.
* This also ensures that it will go away if we crash.
*/
sem_unlink(semname);
return mySem;
}
#else /* !USE_NAMED_POSIX_SEMAPHORES */
/*
* PosixSemaphoreCreate
*
* Attempt to create a new unnamed semaphore.
*/
static void
PosixSemaphoreCreate(sem_t *sem)
{
if (sem_init(sem, 1, 1) < 0)
{
fprintf(stderr, "PosixSemaphoreCreate: sem_init failed: %s\n",
strerror(errno));
proc_exit(1);
}
}
#endif /* USE_NAMED_POSIX_SEMAPHORES */
/*
* PosixSemaphoreKill - removes a semaphore
*/
static void
PosixSemaphoreKill(sem_t *sem)
{
#ifdef USE_NAMED_POSIX_SEMAPHORES
/* Got to use sem_close for named semaphores */
if (sem_close(sem) < 0)
fprintf(stderr, "PosixSemaphoreKill: sem_close failed: %s\n",
strerror(errno));
#else
/* Got to use sem_destroy for unnamed semaphores */
if (sem_destroy(sem) < 0)
fprintf(stderr, "PosixSemaphoreKill: sem_destroy failed: %s\n",
strerror(errno));
#endif
}
/*
* PGReserveSemaphores --- initialize semaphore support
*
* This is called during postmaster start or shared memory reinitialization.
* It should do whatever is needed to be able to support up to maxSemas
* subsequent PGSemaphoreCreate calls. Also, if any system resources
* are acquired here or in PGSemaphoreCreate, register an on_shmem_exit
* callback to release them.
*
* The port number is passed for possible use as a key (for Posix, we use
* it to generate the starting semaphore name). In a standalone backend,
* zero will be passed.
*
* In the Posix implementation, we acquire semaphores on-demand; the
* maxSemas parameter is just used to size the array that keeps track of
* acquired semas for subsequent releasing.
*/
void
PGReserveSemaphores(int maxSemas, int port)
{
mySemPointers = (sem_t **) malloc(maxSemas * sizeof(sem_t *));
if (mySemPointers == NULL)
elog(PANIC, "Out of memory in PGReserveSemaphores");
numSems = 0;
maxSems = maxSemas;
nextSemKey = port * 1000;
on_shmem_exit(ReleaseSemaphores, 0);
}
/*
* Release semaphores at shutdown or shmem reinitialization
*
* (called as an on_shmem_exit callback, hence funny argument list)
*/
static void
ReleaseSemaphores(int status, Datum arg)
{
int i;
for (i = 0; i < numSems; i++)
PosixSemaphoreKill(mySemPointers[i]);
free(mySemPointers);
}
/*
* PGSemaphoreCreate
*
* Initialize a PGSemaphore structure to represent a sema with count 1
*/
void
PGSemaphoreCreate(PGSemaphore sema)
{
sem_t *newsem;
/* Can't do this in a backend, because static state is postmaster's */
Assert(!IsUnderPostmaster);
if (numSems >= maxSems)
elog(PANIC, "PGSemaphoreCreate: too many semaphores created");
#ifdef USE_NAMED_POSIX_SEMAPHORES
*sema = newsem = PosixSemaphoreCreate();
#else
PosixSemaphoreCreate(sema);
newsem = sema;
#endif
/* Remember new sema for ReleaseSemaphores */
mySemPointers[numSems++] = newsem;
}
/*
* PGSemaphoreReset
*
* Reset a previously-initialized PGSemaphore to have count 0
*/
void
PGSemaphoreReset(PGSemaphore sema)
{
/*
* There's no direct API for this in POSIX, so we have to ratchet the
* semaphore down to 0 with repeated trywait's.
*/
for (;;)
{
if (sem_trywait(PG_SEM_REF(sema)) < 0)
{
if (errno == EAGAIN || errno == EDEADLK)
break; /* got it down to 0 */
if (errno == EINTR)
continue; /* can this happen? */
fprintf(stderr, "PGSemaphoreReset: sem_trywait failed: %s\n",
strerror(errno));
proc_exit(1);
}
}
}
/*
* PGSemaphoreLock
*
* Lock a semaphore (decrement count), blocking if count would be < 0
*/
void
PGSemaphoreLock(PGSemaphore sema, bool interruptOK)
{
int errStatus;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and lock the semaphore again.
*
* Each time around the loop, we check for a cancel/die interrupt. We
* assume that if such an interrupt comes in while we are waiting, it
* will cause the sem_wait() call to exit with errno == EINTR, so that we
* will be able to service the interrupt (if not in a critical section
* already).
*
* Once we acquire the lock, we do NOT check for an interrupt before
* returning. The caller needs to be able to record ownership of the
* lock before any interrupt can be accepted.
*
* There is a window of a few instructions between CHECK_FOR_INTERRUPTS
* and entering the sem_wait() call. If a cancel/die interrupt occurs in
* that window, we would fail to notice it until after we acquire the
* lock (or get another interrupt to escape the sem_wait()). We can
* avoid this problem by temporarily setting ImmediateInterruptOK to
* true before we do CHECK_FOR_INTERRUPTS; then, a die() interrupt in
* this interval will execute directly. However, there is a huge
* pitfall: there is another window of a few instructions after the
* sem_wait() before we are able to reset ImmediateInterruptOK. If an
* interrupt occurs then, we'll lose control, which means that the
* lock has been acquired but our caller did not get a chance to
* record the fact. Therefore, we only set ImmediateInterruptOK if the
* caller tells us it's OK to do so, ie, the caller does not need to
* record acquiring the lock. (This is currently true for lockmanager
* locks, since the process that granted us the lock did all the
* necessary state updates. It's not true for Posix semaphores used to
* implement LW locks or emulate spinlocks --- but the wait time for
* such locks should not be very long, anyway.)
*/
do
{
ImmediateInterruptOK = interruptOK;
CHECK_FOR_INTERRUPTS();
errStatus = sem_wait(PG_SEM_REF(sema));
ImmediateInterruptOK = false;
} while (errStatus < 0 && errno == EINTR);
if (errStatus < 0)
{
fprintf(stderr, "PGSemaphoreLock: sem_wait failed: %s\n",
strerror(errno));
proc_exit(255);
}
}
/*
* PGSemaphoreUnlock
*
* Unlock a semaphore (increment count)
*/
void
PGSemaphoreUnlock(PGSemaphore sema)
{
int errStatus;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and unlock the semaphore again. Not clear this
* can really happen, but might as well cope.
*/
do
{
errStatus = sem_post(PG_SEM_REF(sema));
} while (errStatus < 0 && errno == EINTR);
if (errStatus < 0)
{
fprintf(stderr, "PGSemaphoreUnlock: sem_post failed: %s\n",
strerror(errno));
proc_exit(255);
}
}
/*
* PGSemaphoreTryLock
*
* Lock a semaphore only if able to do so without blocking
*/
bool
PGSemaphoreTryLock(PGSemaphore sema)
{
int errStatus;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and lock the semaphore again.
*/
do
{
errStatus = sem_trywait(PG_SEM_REF(sema));
} while (errStatus < 0 && errno == EINTR);
if (errStatus < 0)
{
if (errno == EAGAIN || errno == EDEADLK)
return false; /* failed to lock it */
/* Otherwise we got trouble */
fprintf(stderr, "PGSemaphoreTryLock: sem_trywait failed: %s\n",
strerror(errno));
proc_exit(255);
}
return true;
}

522
src/backend/port/sysv_sema.c Normal file
View File

@ -0,0 +1,522 @@
/*-------------------------------------------------------------------------
*
* sysv_sema.c
* Implement PGSemaphores using SysV semaphore facilities
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/port/sysv_sema.c,v 1.1 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <sys/file.h>
#include <sys/types.h>
#ifdef HAVE_SYS_IPC_H
#include <sys/ipc.h>
#endif
#ifdef HAVE_SYS_SEM_H
#include <sys/sem.h>
#endif
#ifdef HAVE_KERNEL_OS_H
#include <kernel/OS.h>
#endif
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/pg_sema.h"
#ifndef HAVE_UNION_SEMUN
union semun
{
int val;
struct semid_ds *buf;
unsigned short *array;
};
#endif
typedef uint32 IpcSemaphoreKey; /* semaphore key passed to semget(2) */
typedef int IpcSemaphoreId; /* semaphore ID returned by semget(2) */
/*
* SEMAS_PER_SET is the number of useful semaphores in each semaphore set
* we allocate. It must be *less than* your kernel's SEMMSL (max semaphores
* per set) parameter, which is often around 25. (Less than, because we
* allocate one extra sema in each set for identification purposes.)
*/
#define SEMAS_PER_SET 16
#define IPCProtection (0600) /* access/modify by user only */
#define PGSemaMagic 537 /* must be less than SEMVMX */
static IpcSemaphoreId *mySemaSets; /* IDs of sema sets acquired so far */
static int numSemaSets; /* number of sema sets acquired so far */
static int maxSemaSets; /* allocated size of mySemaSets array */
static IpcSemaphoreKey nextSemaKey; /* next key to try using */
static int nextSemaNumber; /* next free sem num in last sema set */
static IpcSemaphoreId InternalIpcSemaphoreCreate(IpcSemaphoreKey semKey,
int numSems);
static void IpcSemaphoreInitialize(IpcSemaphoreId semId, int semNum,
int value);
static void IpcSemaphoreKill(IpcSemaphoreId semId);
static int IpcSemaphoreGetValue(IpcSemaphoreId semId, int semNum);
static pid_t IpcSemaphoreGetLastPID(IpcSemaphoreId semId, int semNum);
static IpcSemaphoreId IpcSemaphoreCreate(int numSems);
static void ReleaseSemaphores(int status, Datum arg);
/*
* InternalIpcSemaphoreCreate
*
* Attempt to create a new semaphore set with the specified key.
* Will fail (return -1) if such a set already exists.
*
* If we fail with a failure code other than collision-with-existing-set,
* print out an error and abort. Other types of errors suggest nonrecoverable
* problems.
*/
static IpcSemaphoreId
InternalIpcSemaphoreCreate(IpcSemaphoreKey semKey, int numSems)
{
int semId;
semId = semget(semKey, numSems, IPC_CREAT | IPC_EXCL | IPCProtection);
if (semId < 0)
{
/*
* Fail quietly if error indicates a collision with existing set.
* One would expect EEXIST, given that we said IPC_EXCL, but
* perhaps we could get a permission violation instead? Also,
* EIDRM might occur if an old set is slated for destruction but
* not gone yet.
*/
if (errno == EEXIST || errno == EACCES
#ifdef EIDRM
|| errno == EIDRM
#endif
)
return -1;
/*
* Else complain and abort
*/
fprintf(stderr, "IpcSemaphoreCreate: semget(key=%d, num=%d, 0%o) failed: %s\n",
(int) semKey, numSems, (IPC_CREAT | IPC_EXCL | IPCProtection),
strerror(errno));
if (errno == ENOSPC)
fprintf(stderr,
"\nThis error does *not* mean that you have run out of disk space.\n"
"\n"
"It occurs when either the system limit for the maximum number of\n"
"semaphore sets (SEMMNI), or the system wide maximum number of\n"
"semaphores (SEMMNS), would be exceeded. You need to raise the\n"
"respective kernel parameter. Alternatively, reduce PostgreSQL's\n"
"consumption of semaphores by reducing its max_connections parameter\n"
"(currently %d).\n"
"\n"
"The PostgreSQL Administrator's Guide contains more information about\n"
"configuring your system for PostgreSQL.\n\n",
MaxBackends);
proc_exit(1);
}
return semId;
}
/*
* Initialize a semaphore to the specified value.
*/
static void
IpcSemaphoreInitialize(IpcSemaphoreId semId, int semNum, int value)
{
union semun semun;
semun.val = value;
if (semctl(semId, semNum, SETVAL, semun) < 0)
{
fprintf(stderr, "IpcSemaphoreInitialize: semctl(id=%d, %d, SETVAL, %d) failed: %s\n",
semId, semNum, value, strerror(errno));
if (errno == ERANGE)
fprintf(stderr,
"You possibly need to raise your kernel's SEMVMX value to be at least\n"
"%d. Look into the PostgreSQL documentation for details.\n",
value);
proc_exit(1);
}
}
/*
* IpcSemaphoreKill(semId) - removes a semaphore set
*/
static void
IpcSemaphoreKill(IpcSemaphoreId semId)
{
union semun semun;
semun.val = 0; /* unused, but keep compiler quiet */
if (semctl(semId, 0, IPC_RMID, semun) < 0)
fprintf(stderr, "IpcSemaphoreKill: semctl(%d, 0, IPC_RMID, ...) failed: %s\n",
semId, strerror(errno));
/*
* We used to report a failure via elog(WARNING), but that's pretty
* pointless considering any client has long since disconnected ...
*/
}
/* Get the current value (semval) of the semaphore */
static int
IpcSemaphoreGetValue(IpcSemaphoreId semId, int semNum)
{
union semun dummy; /* for Solaris */
dummy.val = 0; /* unused */
return semctl(semId, semNum, GETVAL, dummy);
}
/* Get the PID of the last process to do semop() on the semaphore */
static pid_t
IpcSemaphoreGetLastPID(IpcSemaphoreId semId, int semNum)
{
union semun dummy; /* for Solaris */
dummy.val = 0; /* unused */
return semctl(semId, semNum, GETPID, dummy);
}
/*
* Create a semaphore set with the given number of useful semaphores
* (an additional sema is actually allocated to serve as identifier).
* Dead Postgres sema sets are recycled if found, but we do not fail
* upon collision with non-Postgres sema sets.
*
* The idea here is to detect and re-use keys that may have been assigned
* by a crashed postmaster or backend.
*/
static IpcSemaphoreId
IpcSemaphoreCreate(int numSems)
{
IpcSemaphoreId semId;
union semun semun;
PGSemaphoreData mysema;
/* Loop till we find a free IPC key */
for (nextSemaKey++; ; nextSemaKey++)
{
pid_t creatorPID;
/* Try to create new semaphore set */
semId = InternalIpcSemaphoreCreate(nextSemaKey, numSems + 1);
if (semId >= 0)
break; /* successful create */
/* See if it looks to be leftover from a dead Postgres process */
semId = semget(nextSemaKey, numSems + 1, 0);
if (semId < 0)
continue; /* failed: must be some other app's */
if (IpcSemaphoreGetValue(semId, numSems) != PGSemaMagic)
continue; /* sema belongs to a non-Postgres app */
/*
* If the creator PID is my own PID or does not belong to any
* extant process, it's safe to zap it.
*/
creatorPID = IpcSemaphoreGetLastPID(semId, numSems);
if (creatorPID <= 0)
continue; /* oops, GETPID failed */
if (creatorPID != getpid())
{
if (kill(creatorPID, 0) == 0 ||
errno != ESRCH)
continue; /* sema belongs to a live process */
}
/*
* The sema set appears to be from a dead Postgres process, or
* from a previous cycle of life in this same process. Zap it, if
* possible. This probably shouldn't fail, but if it does, assume
* the sema set belongs to someone else after all, and continue
* quietly.
*/
semun.val = 0; /* unused, but keep compiler quiet */
if (semctl(semId, 0, IPC_RMID, semun) < 0)
continue;
/*
* Now try again to create the sema set.
*/
semId = InternalIpcSemaphoreCreate(nextSemaKey, numSems + 1);
if (semId >= 0)
break; /* successful create */
/*
* Can only get here if some other process managed to create the
* same sema key before we did. Let him have that one, loop
* around to try next key.
*/
}
/*
* OK, we created a new sema set. Mark it as created by this process.
* We do this by setting the spare semaphore to PGSemaMagic-1 and then
* incrementing it with semop(). That leaves it with value
* PGSemaMagic and sempid referencing this process.
*/
IpcSemaphoreInitialize(semId, numSems, PGSemaMagic - 1);
mysema.semId = semId;
mysema.semNum = numSems;
PGSemaphoreUnlock(&mysema);
return semId;
}
/*
* PGReserveSemaphores --- initialize semaphore support
*
* This is called during postmaster start or shared memory reinitialization.
* It should do whatever is needed to be able to support up to maxSemas
* subsequent PGSemaphoreCreate calls. Also, if any system resources
* are acquired here or in PGSemaphoreCreate, register an on_shmem_exit
* callback to release them.
*
* The port number is passed for possible use as a key (for SysV, we use
* it to generate the starting semaphore key). In a standalone backend,
* zero will be passed.
*
* In the SysV implementation, we acquire semaphore sets on-demand; the
* maxSemas parameter is just used to size the array that keeps track of
* acquired sets for subsequent releasing.
*/
void
PGReserveSemaphores(int maxSemas, int port)
{
maxSemaSets = (maxSemas + SEMAS_PER_SET-1) / SEMAS_PER_SET;
mySemaSets = (IpcSemaphoreId *)
malloc(maxSemaSets * sizeof(IpcSemaphoreId));
if (mySemaSets == NULL)
elog(PANIC, "Out of memory in PGReserveSemaphores");
numSemaSets = 0;
nextSemaKey = port * 1000;
nextSemaNumber = SEMAS_PER_SET; /* force sema set alloc on 1st call */
on_shmem_exit(ReleaseSemaphores, 0);
}
/*
* Release semaphores at shutdown or shmem reinitialization
*
* (called as an on_shmem_exit callback, hence funny argument list)
*/
static void
ReleaseSemaphores(int status, Datum arg)
{
int i;
for (i = 0; i < numSemaSets; i++)
IpcSemaphoreKill(mySemaSets[i]);
free(mySemaSets);
}
/*
* PGSemaphoreCreate
*
* Initialize a PGSemaphore structure to represent a sema with count 1
*/
void
PGSemaphoreCreate(PGSemaphore sema)
{
/* Can't do this in a backend, because static state is postmaster's */
Assert(!IsUnderPostmaster);
if (nextSemaNumber >= SEMAS_PER_SET)
{
/* Time to allocate another semaphore set */
if (numSemaSets >= maxSemaSets)
elog(PANIC, "PGSemaphoreCreate: too many semaphores created");
mySemaSets[numSemaSets] = IpcSemaphoreCreate(SEMAS_PER_SET);
numSemaSets++;
nextSemaNumber = 0;
}
/* Assign the next free semaphore in the current set */
sema->semId = mySemaSets[numSemaSets-1];
sema->semNum = nextSemaNumber++;
/* Initialize it to count 1 */
IpcSemaphoreInitialize(sema->semId, sema->semNum, 1);
}
/*
* PGSemaphoreReset
*
* Reset a previously-initialized PGSemaphore to have count 0
*/
void
PGSemaphoreReset(PGSemaphore sema)
{
IpcSemaphoreInitialize(sema->semId, sema->semNum, 0);
}
/*
* PGSemaphoreLock
*
* Lock a semaphore (decrement count), blocking if count would be < 0
*/
void
PGSemaphoreLock(PGSemaphore sema, bool interruptOK)
{
int errStatus;
struct sembuf sops;
sops.sem_op = -1; /* decrement */
sops.sem_flg = 0;
sops.sem_num = sema->semNum;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and lock the semaphore again.
*
* Each time around the loop, we check for a cancel/die interrupt. We
* assume that if such an interrupt comes in while we are waiting, it
* will cause the semop() call to exit with errno == EINTR, so that we
* will be able to service the interrupt (if not in a critical section
* already).
*
* Once we acquire the lock, we do NOT check for an interrupt before
* returning. The caller needs to be able to record ownership of the
* lock before any interrupt can be accepted.
*
* There is a window of a few instructions between CHECK_FOR_INTERRUPTS
* and entering the semop() call. If a cancel/die interrupt occurs in
* that window, we would fail to notice it until after we acquire the
* lock (or get another interrupt to escape the semop()). We can
* avoid this problem by temporarily setting ImmediateInterruptOK to
* true before we do CHECK_FOR_INTERRUPTS; then, a die() interrupt in
* this interval will execute directly. However, there is a huge
* pitfall: there is another window of a few instructions after the
* semop() before we are able to reset ImmediateInterruptOK. If an
* interrupt occurs then, we'll lose control, which means that the
* lock has been acquired but our caller did not get a chance to
* record the fact. Therefore, we only set ImmediateInterruptOK if the
* caller tells us it's OK to do so, ie, the caller does not need to
* record acquiring the lock. (This is currently true for lockmanager
* locks, since the process that granted us the lock did all the
* necessary state updates. It's not true for SysV semaphores used to
* implement LW locks or emulate spinlocks --- but the wait time for
* such locks should not be very long, anyway.)
*/
do
{
ImmediateInterruptOK = interruptOK;
CHECK_FOR_INTERRUPTS();
errStatus = semop(sema->semId, &sops, 1);
ImmediateInterruptOK = false;
} while (errStatus < 0 && errno == EINTR);
if (errStatus < 0)
{
fprintf(stderr, "PGSemaphoreLock: semop(id=%d) failed: %s\n",
sema->semId, strerror(errno));
proc_exit(255);
}
}
/*
* PGSemaphoreUnlock
*
* Unlock a semaphore (increment count)
*/
void
PGSemaphoreUnlock(PGSemaphore sema)
{
int errStatus;
struct sembuf sops;
sops.sem_op = 1; /* increment */
sops.sem_flg = 0;
sops.sem_num = sema->semNum;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and unlock the semaphore again. Not clear this
* can really happen, but might as well cope.
*/
do
{
errStatus = semop(sema->semId, &sops, 1);
} while (errStatus < 0 && errno == EINTR);
if (errStatus < 0)
{
fprintf(stderr, "PGSemaphoreUnlock: semop(id=%d) failed: %s\n",
sema->semId, strerror(errno));
proc_exit(255);
}
}
/*
* PGSemaphoreTryLock
*
* Lock a semaphore only if able to do so without blocking
*/
bool
PGSemaphoreTryLock(PGSemaphore sema)
{
int errStatus;
struct sembuf sops;
sops.sem_op = -1; /* decrement */
sops.sem_flg = IPC_NOWAIT; /* but don't block */
sops.sem_num = sema->semNum;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and lock the semaphore again.
*/
do
{
errStatus = semop(sema->semId, &sops, 1);
} while (errStatus < 0 && errno == EINTR);
if (errStatus < 0)
{
/* Expect EAGAIN or EWOULDBLOCK (platform-dependent) */
#ifdef EAGAIN
if (errno == EAGAIN)
return false; /* failed to lock it */
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
if (errno == EWOULDBLOCK)
return false; /* failed to lock it */
#endif
/* Otherwise we got trouble */
fprintf(stderr, "PGSemaphoreTryLock: semop(id=%d) failed: %s\n",
sema->semId, strerror(errno));
proc_exit(255);
}
return true;
}

400
src/backend/port/sysv_shmem.c Normal file
View File

@ -0,0 +1,400 @@
/*-------------------------------------------------------------------------
*
* sysv_shmem.c
* Implement shared memory using SysV facilities
*
* These routines represent a fairly thin layer on top of SysV shared
* memory functionality.
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.1 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <sys/file.h>
#include <sys/types.h>
#ifdef HAVE_SYS_IPC_H
#include <sys/ipc.h>
#endif
#ifdef HAVE_SYS_SHM_H
#include <sys/shm.h>
#endif
#ifdef HAVE_KERNEL_OS_H
#include <kernel/OS.h>
#endif
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/pg_shmem.h"
typedef uint32 IpcMemoryKey; /* shared memory key passed to shmget(2) */
typedef int IpcMemoryId; /* shared memory ID returned by shmget(2) */
#define IPCProtection (0600) /* access/modify by user only */
static void *InternalIpcMemoryCreate(IpcMemoryKey memKey, uint32 size);
static void IpcMemoryDetach(int status, Datum shmaddr);
static void IpcMemoryDelete(int status, Datum shmId);
static void *PrivateMemoryCreate(uint32 size);
static void PrivateMemoryDelete(int status, Datum memaddr);
/*
* InternalIpcMemoryCreate(memKey, size)
*
* Attempt to create a new shared memory segment with the specified key.
* Will fail (return NULL) if such a segment already exists. If successful,
* attach the segment to the current process and return its attached address.
* On success, callbacks are registered with on_shmem_exit to detach and
* delete the segment when on_shmem_exit is called.
*
* If we fail with a failure code other than collision-with-existing-segment,
* print out an error and abort. Other types of errors are not recoverable.
*/
static void *
InternalIpcMemoryCreate(IpcMemoryKey memKey, uint32 size)
{
IpcMemoryId shmid;
void *memAddress;
shmid = shmget(memKey, size, IPC_CREAT | IPC_EXCL | IPCProtection);
if (shmid < 0)
{
/*
* Fail quietly if error indicates a collision with existing
* segment. One would expect EEXIST, given that we said IPC_EXCL,
* but perhaps we could get a permission violation instead? Also,
* EIDRM might occur if an old seg is slated for destruction but
* not gone yet.
*/
if (errno == EEXIST || errno == EACCES
#ifdef EIDRM
|| errno == EIDRM
#endif
)
return NULL;
/*
* Else complain and abort
*/
fprintf(stderr, "IpcMemoryCreate: shmget(key=%d, size=%u, 0%o) failed: %s\n",
(int) memKey, size, (IPC_CREAT | IPC_EXCL | IPCProtection),
strerror(errno));
if (errno == EINVAL)
fprintf(stderr,
"\nThis error usually means that PostgreSQL's request for a shared memory\n"
"segment exceeded your kernel's SHMMAX parameter. You can either\n"
"reduce the request size or reconfigure the kernel with larger SHMMAX.\n"
"To reduce the request size (currently %u bytes), reduce\n"
"PostgreSQL's shared_buffers parameter (currently %d) and/or\n"
"its max_connections parameter (currently %d).\n"
"\n"
"If the request size is already small, it's possible that it is less than\n"
"your kernel's SHMMIN parameter, in which case raising the request size or\n"
"reconfiguring SHMMIN is called for.\n"
"\n"
"The PostgreSQL Administrator's Guide contains more information about\n"
"shared memory configuration.\n\n",
size, NBuffers, MaxBackends);
else if (errno == ENOMEM)
fprintf(stderr,
"\nThis error usually means that PostgreSQL's request for a shared\n"
"memory segment exceeded available memory or swap space.\n"
"To reduce the request size (currently %u bytes), reduce\n"
"PostgreSQL's shared_buffers parameter (currently %d) and/or\n"
"its max_connections parameter (currently %d).\n"
"\n"
"The PostgreSQL Administrator's Guide contains more information about\n"
"shared memory configuration.\n\n",
size, NBuffers, MaxBackends);
else if (errno == ENOSPC)
fprintf(stderr,
"\nThis error does *not* mean that you have run out of disk space.\n"
"\n"
"It occurs either if all available shared memory IDs have been taken,\n"
"in which case you need to raise the SHMMNI parameter in your kernel,\n"
"or because the system's overall limit for shared memory has been\n"
"reached. If you cannot increase the shared memory limit,\n"
"reduce PostgreSQL's shared memory request (currently %u bytes),\n"
"by reducing its shared_buffers parameter (currently %d) and/or\n"
"its max_connections parameter (currently %d).\n"
"\n"
"The PostgreSQL Administrator's Guide contains more information about\n"
"shared memory configuration.\n\n",
size, NBuffers, MaxBackends);
proc_exit(1);
}
/* Register on-exit routine to delete the new segment */
on_shmem_exit(IpcMemoryDelete, Int32GetDatum(shmid));
/* OK, should be able to attach to the segment */
#if defined(solaris) && defined(__sparc__)
/* use intimate shared memory on SPARC Solaris */
memAddress = shmat(shmid, 0, SHM_SHARE_MMU);
#else
memAddress = shmat(shmid, 0, 0);
#endif
if (memAddress == (void *) -1)
{
fprintf(stderr, "IpcMemoryCreate: shmat(id=%d) failed: %s\n",
shmid, strerror(errno));
proc_exit(1);
}
/* Register on-exit routine to detach new segment before deleting */
on_shmem_exit(IpcMemoryDetach, PointerGetDatum(memAddress));
/* Record key and ID in lockfile for data directory. */
RecordSharedMemoryInLockFile((unsigned long) memKey,
(unsigned long) shmid);
return memAddress;
}
/****************************************************************************/
/* IpcMemoryDetach(status, shmaddr) removes a shared memory segment */
/* from process' address spaceq */
/* (called as an on_shmem_exit callback, hence funny argument list) */
/****************************************************************************/
static void
IpcMemoryDetach(int status, Datum shmaddr)
{
if (shmdt(DatumGetPointer(shmaddr)) < 0)
fprintf(stderr, "IpcMemoryDetach: shmdt(%p) failed: %s\n",
DatumGetPointer(shmaddr), strerror(errno));
/*
* We used to report a failure via elog(WARNING), but that's pretty
* pointless considering any client has long since disconnected ...
*/
}
/****************************************************************************/
/* IpcMemoryDelete(status, shmId) deletes a shared memory segment */
/* (called as an on_shmem_exit callback, hence funny argument list) */
/****************************************************************************/
static void
IpcMemoryDelete(int status, Datum shmId)
{
if (shmctl(DatumGetInt32(shmId), IPC_RMID, (struct shmid_ds *) NULL) < 0)
fprintf(stderr, "IpcMemoryDelete: shmctl(%d, %d, 0) failed: %s\n",
DatumGetInt32(shmId), IPC_RMID, strerror(errno));
/*
* We used to report a failure via elog(WARNING), but that's pretty
* pointless considering any client has long since disconnected ...
*/
}
/*
* PGSharedMemoryIsInUse
*
* Is a previously-existing shmem segment still existing and in use?
*/
bool
PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2)
{
IpcMemoryId shmId = (IpcMemoryId) id2;
struct shmid_ds shmStat;
/*
* We detect whether a shared memory segment is in use by seeing
* whether it (a) exists and (b) has any processes are attached to it.
*
* If we are unable to perform the stat operation for a reason other than
* nonexistence of the segment (most likely, because it doesn't belong
* to our userid), assume it is in use.
*/
if (shmctl(shmId, IPC_STAT, &shmStat) < 0)
{
/*
* EINVAL actually has multiple possible causes documented in the
* shmctl man page, but we assume it must mean the segment no
* longer exists.
*/
if (errno == EINVAL)
return false;
/* Else assume segment is in use */
return true;
}
/* If it has attached processes, it's in use */
if (shmStat.shm_nattch != 0)
return true;
return false;
}
/* ----------------------------------------------------------------
* private memory support
*
* Rather than allocating shmem segments with IPC_PRIVATE key, we
* just malloc() the requested amount of space. This code emulates
* the needed shmem functions.
* ----------------------------------------------------------------
*/
static void *
PrivateMemoryCreate(uint32 size)
{
void *memAddress;
memAddress = malloc(size);
if (!memAddress)
{
fprintf(stderr, "PrivateMemoryCreate: malloc(%u) failed\n", size);
proc_exit(1);
}
MemSet(memAddress, 0, size); /* keep Purify quiet */
/* Register on-exit routine to release storage */
on_shmem_exit(PrivateMemoryDelete, PointerGetDatum(memAddress));
return memAddress;
}
static void
PrivateMemoryDelete(int status, Datum memaddr)
{
free(DatumGetPointer(memaddr));
}
/*
* PGSharedMemoryCreate
*
* Create a shared memory segment of the given size and initialize its
* standard header. Also, register an on_shmem_exit callback to release
* the storage.
*
* Dead Postgres segments are recycled if found, but we do not fail upon
* collision with non-Postgres shmem segments. The idea here is to detect and
* re-use keys that may have been assigned by a crashed postmaster or backend.
*
* The port number is passed for possible use as a key (for SysV, we use
* it to generate the starting shmem key). In a standalone backend,
* zero will be passed.
*/
PGShmemHeader *
PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
{
IpcMemoryKey NextShmemSegID;
void *memAddress;
PGShmemHeader *hdr;
/* Room for a header? */
Assert(size > MAXALIGN(sizeof(PGShmemHeader)));
/* Loop till we find a free IPC key */
NextShmemSegID = port * 1000;
for (NextShmemSegID++;; NextShmemSegID++)
{
IpcMemoryId shmid;
/* Special case if creating a private segment --- just malloc() it */
if (makePrivate)
{
memAddress = PrivateMemoryCreate(size);
break;
}
/* Try to create new segment */
memAddress = InternalIpcMemoryCreate(NextShmemSegID, size);
if (memAddress)
break; /* successful create and attach */
/* See if it looks to be leftover from a dead Postgres process */
shmid = shmget(NextShmemSegID, sizeof(PGShmemHeader), 0);
if (shmid < 0)
continue; /* failed: must be some other app's */
#if defined(solaris) && defined(__sparc__)
/* use intimate shared memory on SPARC Solaris */
memAddress = shmat(shmid, 0, SHM_SHARE_MMU);
#else
memAddress = shmat(shmid, 0, 0);
#endif
if (memAddress == (void *) -1)
continue; /* failed: must be some other app's */
hdr = (PGShmemHeader *) memAddress;
if (hdr->magic != PGShmemMagic)
{
shmdt(memAddress);
continue; /* segment belongs to a non-Postgres app */
}
/*
* If the creator PID is my own PID or does not belong to any
* extant process, it's safe to zap it.
*/
if (hdr->creatorPID != getpid())
{
if (kill(hdr->creatorPID, 0) == 0 ||
errno != ESRCH)
{
shmdt(memAddress);
continue; /* segment belongs to a live process */
}
}
/*
* The segment appears to be from a dead Postgres process, or from
* a previous cycle of life in this same process. Zap it, if
* possible. This probably shouldn't fail, but if it does, assume
* the segment belongs to someone else after all, and continue
* quietly.
*/
shmdt(memAddress);
if (shmctl(shmid, IPC_RMID, (struct shmid_ds *) NULL) < 0)
continue;
/*
* Now try again to create the segment.
*/
memAddress = InternalIpcMemoryCreate(NextShmemSegID, size);
if (memAddress)
break; /* successful create and attach */
/*
* Can only get here if some other process managed to create the
* same shmem key before we did. Let him have that one, loop
* around to try next key.
*/
}
/*
* OK, we created a new segment. Mark it as created by this process.
* The order of assignments here is critical so that another Postgres
* process can't see the header as valid but belonging to an invalid
* PID!
*/
hdr = (PGShmemHeader *) memAddress;
hdr->creatorPID = getpid();
hdr->magic = PGShmemMagic;
/*
* Initialize space allocation status for segment.
*/
hdr->totalsize = size;
hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
return hdr;
}

3
src/backend/postmaster/pgstat.c
View File

@ -16,7 +16,7 @@
*
* Copyright (c) 2001, PostgreSQL Global Development Group
*
* $Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.19 2002/04/03 00:27:25 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.20 2002/05/05 00:03:28 tgl Exp $
* ----------
*/
#include "postgres.h"
@ -44,6 +44,7 @@
#include "miscadmin.h"
#include "utils/memutils.h"
#include "storage/backendid.h"
#include "storage/ipc.h"
#include "utils/rel.h"
#include "utils/hsearch.h"
#include "utils/ps_status.h"

17
src/backend/postmaster/postmaster.c
View File

@ -37,7 +37,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.272 2002/04/04 04:25:48 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.273 2002/05/05 00:03:28 tgl Exp $
*
* NOTES
*
@ -1361,18 +1361,15 @@ ClosePostmasterPorts(bool pgstat_too)
static void
reset_shared(unsigned short port)
{
/*
* Reset assignment of shared mem and semaphore IPC keys. Doing this
* means that in normal cases we'll assign the same keys on each
* "cycle of life", and thereby avoid leaving dead IPC objects
* floating around if the postmaster crashes and is restarted.
*/
IpcInitKeyAssignment(port);
/*
* Create or re-create shared memory and semaphores.
*
* Note: in each "cycle of life" we will normally assign the same IPC
* keys (if using SysV shmem and/or semas), since the port number is
* used to determine IPC keys. This helps ensure that we will clean up
* dead IPC objects if the postmaster crashes and is restarted.
*/
CreateSharedMemoryAndSemaphores(false, MaxBackends);
CreateSharedMemoryAndSemaphores(false, MaxBackends, port);
}

3
src/backend/storage/file/fd.c
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.90 2002/03/06 06:10:03 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.91 2002/05/05 00:03:28 tgl Exp $
*
* NOTES:
*
@ -51,6 +51,7 @@
#include "miscadmin.h"
#include "storage/fd.h"
#include "storage/ipc.h"
/* Filename components for OpenTemporaryFile */

812
src/backend/storage/ipc/ipc.c
View File

@ -3,25 +3,17 @@
* ipc.c
* POSTGRES inter-process communication definitions.
*
* This file is misnamed, as it no longer has much of anything directly
* to do with IPC. The functionality here is concerned with managing
* exit-time cleanup for either a postmaster or a backend.
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipc.c,v 1.78 2002/04/13 19:52:51 momjian Exp $
*
* NOTES
*
* Currently, semaphores are used (my understanding anyway) in two
* different ways:
* 1. as mutexes on machines that don't have test-and-set (eg.
* mips R3000).
* 2. for putting processes to sleep when waiting on a lock
* and waking them up when the lock is free.
* The number of semaphores in (1) is fixed and those are shared
* among all backends. In (2), there is 1 semaphore per process and those
* are not shared with anyone else.
* -ay 4/95
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipc.c,v 1.79 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -30,27 +22,9 @@
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <sys/file.h>
#include "storage/ipc.h"
/* In Ultrix, sem.h and shm.h must be included AFTER ipc.h */
#ifdef HAVE_SYS_SEM_H
#include <sys/sem.h>
#endif
#ifdef HAVE_SYS_SHM_H
#include <sys/shm.h>
#endif
#ifdef HAVE_KERNEL_OS_H
#include <kernel/OS.h>
#endif
#if defined(__darwin__)
#include "port/darwin/sem.h"
#endif
#include "miscadmin.h"
#include "utils/memutils.h"
#include "libpq/libpq.h"
#include "storage/ipc.h"
/*
@ -60,17 +34,6 @@
*/
bool proc_exit_inprogress = false;
static IpcSemaphoreId InternalIpcSemaphoreCreate(IpcSemaphoreKey semKey,
int numSems, int permission,
int semStartValue, bool removeOnExit);
static void CallbackSemaphoreKill(int status, Datum semId);
static void *InternalIpcMemoryCreate(IpcMemoryKey memKey, uint32 size,
int permission);
static void IpcMemoryDetach(int status, Datum shmaddr);
static void IpcMemoryDelete(int status, Datum shmId);
static void *PrivateMemoryCreate(uint32 size);
static void PrivateMemoryDelete(int status, Datum memaddr);
/* ----------------------------------------------------------------
* exit() handling stuff
@ -83,8 +46,6 @@ static void PrivateMemoryDelete(int status, Datum memaddr);
* Callback functions can take zero, one, or two args: the first passed
* arg is the integer exitcode, the second is the Datum supplied when
* the callback was registered.
*
* XXX these functions probably ought to live in some other module.
* ----------------------------------------------------------------
*/
@ -230,762 +191,3 @@ on_exit_reset(void)
on_shmem_exit_index = 0;
on_proc_exit_index = 0;
}
/* ----------------------------------------------------------------
* Semaphore support
*
* These routines represent a fairly thin layer on top of SysV semaphore
* functionality.
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* InternalIpcSemaphoreCreate(semKey, numSems, permission,
* semStartValue, removeOnExit)
*
* Attempt to create a new semaphore set with the specified key.
* Will fail (return -1) if such a set already exists.
* On success, a callback is optionally registered with on_shmem_exit
* to delete the semaphore set when on_shmem_exit is called.
*
* If we fail with a failure code other than collision-with-existing-set,
* print out an error and abort. Other types of errors are not recoverable.
* ----------------------------------------------------------------
*/
static IpcSemaphoreId
InternalIpcSemaphoreCreate(IpcSemaphoreKey semKey,
int numSems, int permission,
int semStartValue, bool removeOnExit)
{
int semId;
int i;
u_short array[IPC_NMAXSEM];
union semun semun;
Assert(numSems > 0 && numSems <= IPC_NMAXSEM);
semId = semget(semKey, numSems, IPC_CREAT | IPC_EXCL | permission);
if (semId < 0)
{
/*
* Fail quietly if error indicates a collision with existing set.
* One would expect EEXIST, given that we said IPC_EXCL, but
* perhaps we could get a permission violation instead? Also,
* EIDRM might occur if an old set is slated for destruction but
* not gone yet.
*/
if (errno == EEXIST || errno == EACCES
#ifdef EIDRM
|| errno == EIDRM
#endif
)
return -1;
/*
* Else complain and abort
*/
fprintf(stderr, "IpcSemaphoreCreate: semget(key=%d, num=%d, 0%o) failed: %s\n",
(int) semKey, numSems, (IPC_CREAT | IPC_EXCL | permission),
strerror(errno));
if (errno == ENOSPC)
fprintf(stderr,
"\nThis error does *not* mean that you have run out of disk space.\n"
"\n"
"It occurs when either the system limit for the maximum number of\n"
"semaphore sets (SEMMNI), or the system wide maximum number of\n"
"semaphores (SEMMNS), would be exceeded. You need to raise the\n"
"respective kernel parameter. Alternatively, reduce PostgreSQL's\n"
"consumption of semaphores by reducing its max_connections parameter\n"
"(currently %d).\n"
"\n"
"The PostgreSQL Administrator's Guide contains more information about\n"
"configuring your system for PostgreSQL.\n\n",
MaxBackends);
proc_exit(1);
}
/* Initialize new semas to specified start value */
for (i = 0; i < numSems; i++)
array[i] = semStartValue;
semun.array = array;
if (semctl(semId, 0, SETALL, semun) < 0)
{
fprintf(stderr, "IpcSemaphoreCreate: semctl(id=%d, 0, SETALL, ...) failed: %s\n",
semId, strerror(errno));
if (errno == ERANGE)
fprintf(stderr,
"You possibly need to raise your kernel's SEMVMX value to be at least\n"
"%d. Look into the PostgreSQL documentation for details.\n",
semStartValue);
IpcSemaphoreKill(semId);
proc_exit(1);
}
/* Register on-exit routine to delete the new set */
if (removeOnExit)
on_shmem_exit(CallbackSemaphoreKill, Int32GetDatum(semId));
return semId;
}
/****************************************************************************/
/* IpcSemaphoreKill(semId) - removes a semaphore set */
/* */
/****************************************************************************/
void
IpcSemaphoreKill(IpcSemaphoreId semId)
{
union semun semun;
semun.val = 0; /* unused, but keep compiler quiet */
if (semctl(semId, 0, IPC_RMID, semun) < 0)
fprintf(stderr, "IpcSemaphoreKill: semctl(%d, 0, IPC_RMID, ...) failed: %s\n",
semId, strerror(errno));
/*
* We used to report a failure via elog(WARNING), but that's pretty
* pointless considering any client has long since disconnected ...
*/
}
/****************************************************************************/
/* CallbackSemaphoreKill(status, semId) */
/* (called as an on_shmem_exit callback, hence funny argument list) */
/****************************************************************************/
static void
CallbackSemaphoreKill(int status, Datum semId)
{
IpcSemaphoreKill(DatumGetInt32(semId));
}
/****************************************************************************/
/* IpcSemaphoreLock(semId, sem) - locks a semaphore */
/****************************************************************************/
void
IpcSemaphoreLock(IpcSemaphoreId semId, int sem, bool interruptOK)
{
int errStatus;
struct sembuf sops;
sops.sem_op = -1; /* decrement */
sops.sem_flg = 0;
sops.sem_num = sem;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and lock the semaphore again.
*
* Each time around the loop, we check for a cancel/die interrupt. We
* assume that if such an interrupt comes in while we are waiting, it
* will cause the semop() call to exit with errno == EINTR, so that we
* will be able to service the interrupt (if not in a critical section
* already).
*
* Once we acquire the lock, we do NOT check for an interrupt before
* returning. The caller needs to be able to record ownership of the
* lock before any interrupt can be accepted.
*
* There is a window of a few instructions between CHECK_FOR_INTERRUPTS
* and entering the semop() call. If a cancel/die interrupt occurs in
* that window, we would fail to notice it until after we acquire the
* lock (or get another interrupt to escape the semop()). We can
* avoid this problem by temporarily setting ImmediateInterruptOK to
* true before we do CHECK_FOR_INTERRUPTS; then, a die() interrupt in
* this interval will execute directly. However, there is a huge
* pitfall: there is another window of a few instructions after the
* semop() before we are able to reset ImmediateInterruptOK. If an
* interrupt occurs then, we'll lose control, which means that the
* lock has been acquired but our caller did not get a chance to
* record the fact. Therefore, we only set ImmediateInterruptOK if the
* caller tells us it's OK to do so, ie, the caller does not need to
* record acquiring the lock. (This is currently true for lockmanager
* locks, since the process that granted us the lock did all the
* necessary state updates. It's not true for SysV semaphores used to
* implement LW locks or emulate spinlocks --- but the wait time for
* such locks should not be very long, anyway.)
*/
do
{
ImmediateInterruptOK = interruptOK;
CHECK_FOR_INTERRUPTS();
errStatus = semop(semId, &sops, 1);
ImmediateInterruptOK = false;
} while (errStatus == -1 && errno == EINTR);
if (errStatus == -1)
{
fprintf(stderr, "IpcSemaphoreLock: semop(id=%d) failed: %s\n",
semId, strerror(errno));
proc_exit(255);
}
}
/****************************************************************************/
/* IpcSemaphoreUnlock(semId, sem) - unlocks a semaphore */
/****************************************************************************/
void
IpcSemaphoreUnlock(IpcSemaphoreId semId, int sem)
{
int errStatus;
struct sembuf sops;
sops.sem_op = 1; /* increment */
sops.sem_flg = 0;
sops.sem_num = sem;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and unlock the semaphore again. Not clear this
* can really happen, but might as well cope.
*/
do
{
errStatus = semop(semId, &sops, 1);
} while (errStatus == -1 && errno == EINTR);
if (errStatus == -1)
{
fprintf(stderr, "IpcSemaphoreUnlock: semop(id=%d) failed: %s\n",
semId, strerror(errno));
proc_exit(255);
}
}
/****************************************************************************/
/* IpcSemaphoreTryLock(semId, sem) - conditionally locks a semaphore */
/* Lock the semaphore if it's free, but don't block. */
/****************************************************************************/
bool
IpcSemaphoreTryLock(IpcSemaphoreId semId, int sem)
{
int errStatus;
struct sembuf sops;
sops.sem_op = -1; /* decrement */
sops.sem_flg = IPC_NOWAIT; /* but don't block */
sops.sem_num = sem;
/*
* Note: if errStatus is -1 and errno == EINTR then it means we
* returned from the operation prematurely because we were sent a
* signal. So we try and lock the semaphore again.
*/
do
{
errStatus = semop(semId, &sops, 1);
} while (errStatus == -1 && errno == EINTR);
if (errStatus == -1)
{
/* Expect EAGAIN or EWOULDBLOCK (platform-dependent) */
#ifdef EAGAIN
if (errno == EAGAIN)
return false; /* failed to lock it */
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
if (errno == EWOULDBLOCK)
return false; /* failed to lock it */
#endif
/* Otherwise we got trouble */
fprintf(stderr, "IpcSemaphoreTryLock: semop(id=%d) failed: %s\n",
semId, strerror(errno));
proc_exit(255);
}
return true;
}
/* Get the current value (semval) of the semaphore */
int
IpcSemaphoreGetValue(IpcSemaphoreId semId, int sem)
{
union semun dummy; /* for Solaris */
dummy.val = 0; /* unused */
return semctl(semId, sem, GETVAL, dummy);
}
/* Get the PID of the last process to do semop() on the semaphore */
static pid_t
IpcSemaphoreGetLastPID(IpcSemaphoreId semId, int sem)
{
union semun dummy; /* for Solaris */
dummy.val = 0; /* unused */
return semctl(semId, sem, GETPID, dummy);
}
/* ----------------------------------------------------------------
* Shared memory support
*
* These routines represent a fairly thin layer on top of SysV shared
* memory functionality.
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* InternalIpcMemoryCreate(memKey, size, permission)
*
* Attempt to create a new shared memory segment with the specified key.
* Will fail (return NULL) if such a segment already exists. If successful,
* attach the segment to the current process and return its attached address.
* On success, callbacks are registered with on_shmem_exit to detach and
* delete the segment when on_shmem_exit is called.
*
* If we fail with a failure code other than collision-with-existing-segment,
* print out an error and abort. Other types of errors are not recoverable.
* ----------------------------------------------------------------
*/
static void *
InternalIpcMemoryCreate(IpcMemoryKey memKey, uint32 size, int permission)
{
IpcMemoryId shmid;
void *memAddress;
shmid = shmget(memKey, size, IPC_CREAT | IPC_EXCL | permission);
if (shmid < 0)
{
/*
* Fail quietly if error indicates a collision with existing
* segment. One would expect EEXIST, given that we said IPC_EXCL,
* but perhaps we could get a permission violation instead? Also,
* EIDRM might occur if an old seg is slated for destruction but
* not gone yet.
*/
if (errno == EEXIST || errno == EACCES
#ifdef EIDRM
|| errno == EIDRM
#endif
)
return NULL;
/*
* Else complain and abort
*/
fprintf(stderr, "IpcMemoryCreate: shmget(key=%d, size=%u, 0%o) failed: %s\n",
(int) memKey, size, (IPC_CREAT | IPC_EXCL | permission),
strerror(errno));
if (errno == EINVAL)
fprintf(stderr,
"\nThis error usually means that PostgreSQL's request for a shared memory\n"
"segment exceeded your kernel's SHMMAX parameter. You can either\n"
"reduce the request size or reconfigure the kernel with larger SHMMAX.\n"
"To reduce the request size (currently %u bytes), reduce\n"
"PostgreSQL's shared_buffers parameter (currently %d) and/or\n"
"its max_connections parameter (currently %d).\n"
"\n"
"If the request size is already small, it's possible that it is less than\n"
"your kernel's SHMMIN parameter, in which case raising the request size or\n"
"reconfiguring SHMMIN is called for.\n"
"\n"
"The PostgreSQL Administrator's Guide contains more information about\n"
"shared memory configuration.\n\n",
size, NBuffers, MaxBackends);
else if (errno == ENOMEM)
fprintf(stderr,
"\nThis error usually means that PostgreSQL's request for a shared\n"
"memory segment exceeded available memory or swap space.\n"
"To reduce the request size (currently %u bytes), reduce\n"
"PostgreSQL's shared_buffers parameter (currently %d) and/or\n"
"its max_connections parameter (currently %d).\n"
"\n"
"The PostgreSQL Administrator's Guide contains more information about\n"
"shared memory configuration.\n\n",
size, NBuffers, MaxBackends);
else if (errno == ENOSPC)
fprintf(stderr,
"\nThis error does *not* mean that you have run out of disk space.\n"
"\n"
"It occurs either if all available shared memory IDs have been taken,\n"
"in which case you need to raise the SHMMNI parameter in your kernel,\n"
"or because the system's overall limit for shared memory has been\n"
"reached. If you cannot increase the shared memory limit,\n"
"reduce PostgreSQL's shared memory request (currently %u bytes),\n"
"by reducing its shared_buffers parameter (currently %d) and/or\n"
"its max_connections parameter (currently %d).\n"
"\n"
"The PostgreSQL Administrator's Guide contains more information about\n"
"shared memory configuration.\n\n",
size, NBuffers, MaxBackends);
proc_exit(1);
}
/* Register on-exit routine to delete the new segment */
on_shmem_exit(IpcMemoryDelete, Int32GetDatum(shmid));
/* OK, should be able to attach to the segment */
#if defined(solaris) && defined(__sparc__)
/* use intimate shared memory on SPARC Solaris */
memAddress = shmat(shmid, 0, SHM_SHARE_MMU);
#else
memAddress = shmat(shmid, 0, 0);
#endif
if (memAddress == (void *) -1)
{
fprintf(stderr, "IpcMemoryCreate: shmat(id=%d) failed: %s\n",
shmid, strerror(errno));
proc_exit(1);
}
/* Register on-exit routine to detach new segment before deleting */
on_shmem_exit(IpcMemoryDetach, PointerGetDatum(memAddress));
/* Record key and ID in lockfile for data directory. */
RecordSharedMemoryInLockFile(memKey, shmid);
return memAddress;
}
/****************************************************************************/
/* IpcMemoryDetach(status, shmaddr) removes a shared memory segment */
/* from process' address spaceq */
/* (called as an on_shmem_exit callback, hence funny argument list) */
/****************************************************************************/
static void
IpcMemoryDetach(int status, Datum shmaddr)
{
if (shmdt(DatumGetPointer(shmaddr)) < 0)
fprintf(stderr, "IpcMemoryDetach: shmdt(%p) failed: %s\n",
DatumGetPointer(shmaddr), strerror(errno));
/*
* We used to report a failure via elog(WARNING), but that's pretty
* pointless considering any client has long since disconnected ...
*/
}
/****************************************************************************/
/* IpcMemoryDelete(status, shmId) deletes a shared memory segment */
/* (called as an on_shmem_exit callback, hence funny argument list) */
/****************************************************************************/
static void
IpcMemoryDelete(int status, Datum shmId)
{
if (shmctl(DatumGetInt32(shmId), IPC_RMID, (struct shmid_ds *) NULL) < 0)
fprintf(stderr, "IpcMemoryDelete: shmctl(%d, %d, 0) failed: %s\n",
DatumGetInt32(shmId), IPC_RMID, strerror(errno));
/*
* We used to report a failure via elog(WARNING), but that's pretty
* pointless considering any client has long since disconnected ...
*/
}
/****************************************************************************/
/* SharedMemoryIsInUse(shmKey, shmId) Is a shared memory segment in use? */
/****************************************************************************/
bool
SharedMemoryIsInUse(IpcMemoryKey shmKey, IpcMemoryId shmId)
{
struct shmid_ds shmStat;
/*
* We detect whether a shared memory segment is in use by seeing
* whether it (a) exists and (b) has any processes are attached to it.
*
* If we are unable to perform the stat operation for a reason other than
* nonexistence of the segment (most likely, because it doesn't belong
* to our userid), assume it is in use.
*/
if (shmctl(shmId, IPC_STAT, &shmStat) < 0)
{
/*
* EINVAL actually has multiple possible causes documented in the
* shmctl man page, but we assume it must mean the segment no
* longer exists.
*/
if (errno == EINVAL)
return false;
/* Else assume segment is in use */
return true;
}
/* If it has attached processes, it's in use */
if (shmStat.shm_nattch != 0)
return true;
return false;
}
/* ----------------------------------------------------------------
* private memory support
*
* Rather than allocating shmem segments with IPC_PRIVATE key, we
* just malloc() the requested amount of space. This code emulates
* the needed shmem functions.
* ----------------------------------------------------------------
*/
static void *
PrivateMemoryCreate(uint32 size)
{
void *memAddress;
memAddress = malloc(size);
if (!memAddress)
{
fprintf(stderr, "PrivateMemoryCreate: malloc(%u) failed\n", size);
proc_exit(1);
}
MemSet(memAddress, 0, size); /* keep Purify quiet */
/* Register on-exit routine to release storage */
on_shmem_exit(PrivateMemoryDelete, PointerGetDatum(memAddress));
return memAddress;
}
static void
PrivateMemoryDelete(int status, Datum memaddr)
{
free(DatumGetPointer(memaddr));
}
/* ------------------
* Routines to assign keys for new IPC objects
*
* The idea here is to detect and re-use keys that may have been assigned
* by a crashed postmaster or backend.
* ------------------
*/
static IpcMemoryKey NextShmemSegID = 0;
static IpcSemaphoreKey NextSemaID = 0;
/*
* (Re) initialize key assignment at startup of postmaster or standalone
* backend, also at postmaster reset.
*/
void
IpcInitKeyAssignment(int port)
{
NextShmemSegID = port * 1000;
NextSemaID = port * 1000;
}
/*
* Create a shared memory segment of the given size and initialize its
* standard header. Dead Postgres segments are recycled if found,
* but we do not fail upon collision with non-Postgres shmem segments.
*/
PGShmemHeader *
IpcMemoryCreate(uint32 size, bool makePrivate, int permission)
{
void *memAddress;
PGShmemHeader *hdr;
/* Room for a header? */
Assert(size > MAXALIGN(sizeof(PGShmemHeader)));
/* Loop till we find a free IPC key */
for (NextShmemSegID++;; NextShmemSegID++)
{
IpcMemoryId shmid;
/* Special case if creating a private segment --- just malloc() it */
if (makePrivate)
{
memAddress = PrivateMemoryCreate(size);
break;
}
/* Try to create new segment */
memAddress = InternalIpcMemoryCreate(NextShmemSegID, size, permission);
if (memAddress)
break; /* successful create and attach */
/* See if it looks to be leftover from a dead Postgres process */
shmid = shmget(NextShmemSegID, sizeof(PGShmemHeader), 0);
if (shmid < 0)
continue; /* failed: must be some other app's */
#if defined(solaris) && defined(__sparc__)
/* use intimate shared memory on SPARC Solaris */
memAddress = shmat(shmid, 0, SHM_SHARE_MMU);
#else
memAddress = shmat(shmid, 0, 0);
#endif
if (memAddress == (void *) -1)
continue; /* failed: must be some other app's */
hdr = (PGShmemHeader *) memAddress;
if (hdr->magic != PGShmemMagic)
{
shmdt(memAddress);
continue; /* segment belongs to a non-Postgres app */
}
/*
* If the creator PID is my own PID or does not belong to any
* extant process, it's safe to zap it.
*/
if (hdr->creatorPID != getpid())
{
if (kill(hdr->creatorPID, 0) == 0 ||
errno != ESRCH)
{
shmdt(memAddress);
continue; /* segment belongs to a live process */
}
}
/*
* The segment appears to be from a dead Postgres process, or from
* a previous cycle of life in this same process. Zap it, if
* possible. This probably shouldn't fail, but if it does, assume
* the segment belongs to someone else after all, and continue
* quietly.
*/
shmdt(memAddress);
if (shmctl(shmid, IPC_RMID, (struct shmid_ds *) NULL) < 0)
continue;
/*
* Now try again to create the segment.
*/
memAddress = InternalIpcMemoryCreate(NextShmemSegID, size, permission);
if (memAddress)
break; /* successful create and attach */
/*
* Can only get here if some other process managed to create the
* same shmem key before we did. Let him have that one, loop
* around to try next key.
*/
}
/*
* OK, we created a new segment. Mark it as created by this process.
* The order of assignments here is critical so that another Postgres
* process can't see the header as valid but belonging to an invalid
* PID!
*/
hdr = (PGShmemHeader *) memAddress;
hdr->creatorPID = getpid();
hdr->magic = PGShmemMagic;
/*
* Initialize space allocation status for segment.
*/
hdr->totalsize = size;
hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
return hdr;
}
/*
* Create a semaphore set with the given number of useful semaphores
* (an additional sema is actually allocated to serve as identifier).
* Dead Postgres sema sets are recycled if found, but we do not fail
* upon collision with non-Postgres sema sets.
*/
IpcSemaphoreId
IpcSemaphoreCreate(int numSems, int permission,
int semStartValue, bool removeOnExit)
{
IpcSemaphoreId semId;
union semun semun;
/* Loop till we find a free IPC key */
for (NextSemaID++;; NextSemaID++)
{
pid_t creatorPID;
/* Try to create new semaphore set */
semId = InternalIpcSemaphoreCreate(NextSemaID, numSems + 1,
permission, semStartValue,
removeOnExit);
if (semId >= 0)
break; /* successful create */
/* See if it looks to be leftover from a dead Postgres process */
semId = semget(NextSemaID, numSems + 1, 0);
if (semId < 0)
continue; /* failed: must be some other app's */
if (IpcSemaphoreGetValue(semId, numSems) != PGSemaMagic)
continue; /* sema belongs to a non-Postgres app */
/*
* If the creator PID is my own PID or does not belong to any
* extant process, it's safe to zap it.
*/
creatorPID = IpcSemaphoreGetLastPID(semId, numSems);
if (creatorPID <= 0)
continue; /* oops, GETPID failed */
if (creatorPID != getpid())
{
if (kill(creatorPID, 0) == 0 ||
errno != ESRCH)
continue; /* sema belongs to a live process */
}
/*
* The sema set appears to be from a dead Postgres process, or
* from a previous cycle of life in this same process. Zap it, if
* possible. This probably shouldn't fail, but if it does, assume
* the sema set belongs to someone else after all, and continue
* quietly.
*/
semun.val = 0; /* unused, but keep compiler quiet */
if (semctl(semId, 0, IPC_RMID, semun) < 0)
continue;
/*
* Now try again to create the sema set.
*/
semId = InternalIpcSemaphoreCreate(NextSemaID, numSems + 1,
permission, semStartValue,
removeOnExit);
if (semId >= 0)
break; /* successful create */
/*
* Can only get here if some other process managed to create the
* same sema key before we did. Let him have that one, loop
* around to try next key.
*/
}
/*
* OK, we created a new sema set. Mark it as created by this process.
* We do this by setting the spare semaphore to PGSemaMagic-1 and then
* incrementing it with semop(). That leaves it with value
* PGSemaMagic and sempid referencing this process.
*/
semun.val = PGSemaMagic - 1;
if (semctl(semId, numSems, SETVAL, semun) < 0)
{
fprintf(stderr, "IpcSemaphoreCreate: semctl(id=%d, %d, SETVAL, %d) failed: %s\n",
semId, numSems, PGSemaMagic - 1, strerror(errno));
if (errno == ERANGE)
fprintf(stderr,
"You possibly need to raise your kernel's SEMVMX value to be at least\n"
"%d. Look into the PostgreSQL documentation for details.\n",
PGSemaMagic);
proc_exit(1);
}
IpcSemaphoreUnlock(semId, numSems);
return semId;
}

18
src/backend/storage/ipc/ipci.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.46 2002/03/02 21:39:29 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.47 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -21,8 +21,11 @@
#include "access/xlog.h"
#include "storage/bufmgr.h"
#include "storage/freespace.h"
#include "storage/ipc.h"
#include "storage/lmgr.h"
#include "storage/lwlock.h"
#include "storage/pg_sema.h"
#include "storage/pg_shmem.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/sinval.h"
@ -41,9 +44,12 @@
* memory. This is true for a standalone backend, false for a postmaster.
*/
void
CreateSharedMemoryAndSemaphores(bool makePrivate, int maxBackends)
CreateSharedMemoryAndSemaphores(bool makePrivate,
int maxBackends,
int port)
{
int size;
int numSemas;
PGShmemHeader *seghdr;
/*
@ -70,12 +76,14 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int maxBackends)
/*
* Create the shmem segment
*/
seghdr = IpcMemoryCreate(size, makePrivate, IPCProtection);
seghdr = PGSharedMemoryCreate(size, makePrivate, port);
/*
* First initialize spinlocks --- needed by InitShmemAllocation()
* Create semaphores
*/
CreateSpinlocks();
numSemas = ProcGlobalSemas(maxBackends);
numSemas += SpinlockSemas();
PGReserveSemaphores(numSemas, port);
/*
* Set up shared memory allocation mechanism

3
src/backend/storage/ipc/shmem.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.64 2002/03/06 06:10:05 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.65 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -61,6 +61,7 @@
#include "postgres.h"
#include "access/transam.h"
#include "storage/pg_shmem.h"
#include "storage/spin.h"
#include "utils/tqual.h"

3
src/backend/storage/ipc/sinvaladt.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.45 2002/03/02 23:35:57 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.46 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -16,6 +16,7 @@
#include "miscadmin.h"
#include "storage/backendid.h"
#include "storage/ipc.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/sinvaladt.h"

8
src/backend/storage/lmgr/lwlock.c
View File

@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lwlock.c,v 1.9 2002/03/02 21:39:29 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lwlock.c,v 1.10 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -302,7 +302,7 @@ LWLockAcquire(LWLockId lockid, LWLockMode mode)
for (;;)
{
/* "false" means cannot accept cancel/die interrupt here. */
IpcSemaphoreLock(proc->sem.semId, proc->sem.semNum, false);
PGSemaphoreLock(&proc->sem, false);
if (!proc->lwWaiting)
break;
extraWaits++;
@ -325,7 +325,7 @@ LWLockAcquire(LWLockId lockid, LWLockMode mode)
* Fix the process wait semaphore's count for any absorbed wakeups.
*/
while (extraWaits-- > 0)
IpcSemaphoreUnlock(proc->sem.semId, proc->sem.semNum);
PGSemaphoreUnlock(&proc->sem);
}
/*
@ -485,7 +485,7 @@ LWLockRelease(LWLockId lockid)
head = proc->lwWaitLink;
proc->lwWaitLink = NULL;
proc->lwWaiting = false;
IpcSemaphoreUnlock(proc->sem.semId, proc->sem.semNum);
PGSemaphoreUnlock(&proc->sem);
}
/*

294
src/backend/storage/lmgr/proc.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.118 2002/03/02 21:39:29 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.119 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -37,12 +37,6 @@
* in the first place was to allow the lock table to grow larger
* than available shared memory and that isn't going to work
* without a lot of unimplemented support anyway.
*
* 4/7/95 -- instead of allocating a set of 1 semaphore per process, we
* allocate a semaphore from a set of PROC_NSEMS_PER_SET semaphores
* shared among backends (we keep a few sets of semaphores around).
* This is so that we can support more backends. (system-wide semaphore
* sets run out pretty fast.) -ay 4/95
*/
#include "postgres.h"
@ -51,18 +45,9 @@
#include <unistd.h>
#include <sys/time.h>
#include "storage/ipc.h"
/* In Ultrix, sem.h and shm.h must be included AFTER ipc.h */
#ifdef HAVE_SYS_SEM_H
#include <sys/sem.h>
#endif
#if defined(__darwin__)
#include "port/darwin/sem.h"
#endif
#include "miscadmin.h"
#include "access/xact.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "storage/sinval.h"
#include "storage/spin.h"
@ -73,11 +58,11 @@ int DeadlockTimeout = 1000;
PROC *MyProc = NULL;
/*
* This spinlock protects the freelist of recycled PROC structures and the
* bitmap of free semaphores. We cannot use an LWLock because the LWLock
* manager depends on already having a PROC and a wait semaphore! But these
* structures are touched relatively infrequently (only at backend startup
* or shutdown) and not for very long, so a spinlock is okay.
* This spinlock protects the freelist of recycled PROC structures.
* We cannot use an LWLock because the LWLock manager depends on already
* having a PROC and a wait semaphore! But these structures are touched
* relatively infrequently (only at backend startup or shutdown) and not for
* very long, so a spinlock is okay.
*/
static slock_t *ProcStructLock = NULL;
@ -90,21 +75,24 @@ static bool waitingForSignal = false;
static void ProcKill(void);
static void DummyProcKill(void);
static void ProcGetNewSemIdAndNum(IpcSemaphoreId *semId, int *semNum);
static void ProcFreeSem(IpcSemaphoreId semId, int semNum);
static void ZeroProcSemaphore(PROC *proc);
static void ProcFreeAllSemaphores(void);
/*
* Report number of semaphores needed by InitProcGlobal.
*/
int
ProcGlobalSemas(int maxBackends)
{
/* We need a sema per backend, plus one for the dummy process. */
return maxBackends + 1;
}
/*
* InitProcGlobal -
* initializes the global process table. We put it here so that
* the postmaster can do this initialization. (ProcFreeAllSemaphores needs
* to read this table on exiting the postmaster. If we have the first
* backend do this, starting up and killing the postmaster without
* starting any backends will be a problem.)
* the postmaster can do this initialization.
*
* We also allocate all the per-process semaphores we will need to support
* We also create all the per-process semaphores we will need to support
* the requested number of backends. We used to allocate semaphores
* only when backends were actually started up, but that is bad because
* it lets Postgres fail under load --- a lot of Unix systems are
@ -114,28 +102,19 @@ static void ProcFreeAllSemaphores(void);
* of backends immediately at initialization --- if the sysadmin has set
* MaxBackends higher than his kernel will support, he'll find out sooner
* rather than later.
*
* Another reason for creating semaphores here is that the semaphore
* implementation typically requires us to create semaphores in the
* postmaster, not in backends.
*/
void
InitProcGlobal(int maxBackends)
{
int semMapEntries;
Size procGlobalSize;
bool found = false;
/*
* Compute size for ProcGlobal structure. Note we need one more sema
* besides those used for regular backends; this is accounted for in
* the PROC_SEM_MAP_ENTRIES macro. (We do it that way so that other
* modules that use PROC_SEM_MAP_ENTRIES(maxBackends) to size data
* structures don't have to know about this explicitly.)
*/
Assert(maxBackends > 0);
semMapEntries = PROC_SEM_MAP_ENTRIES(maxBackends);
procGlobalSize = sizeof(PROC_HDR) + (semMapEntries - 1) *sizeof(SEM_MAP_ENTRY);
/* Create or attach to the ProcGlobal shared structure */
ProcGlobal = (PROC_HDR *)
ShmemInitStruct("Proc Header", procGlobalSize, &found);
ShmemInitStruct("Proc Header", sizeof(PROC_HDR), &found);
/* --------------------
* We're the first - initialize.
@ -148,47 +127,33 @@ InitProcGlobal(int maxBackends)
int i;
ProcGlobal->freeProcs = INVALID_OFFSET;
ProcGlobal->semMapEntries = semMapEntries;
for (i = 0; i < semMapEntries; i++)
{
ProcGlobal->procSemMap[i].procSemId = -1;
ProcGlobal->procSemMap[i].freeSemMap = 0;
}
/*
* Arrange to delete semas on exit --- set this up now so that we
* will clean up if pre-allocation fails. We use our own
* freeproc, rather than IpcSemaphoreCreate's removeOnExit option,
* because we don't want to fill up the on_shmem_exit list with a
* separate entry for each semaphore set.
* Pre-create the PROC structures and create a semaphore for each.
*/
on_shmem_exit(ProcFreeAllSemaphores, 0);
/*
* Pre-create the semaphores.
*/
for (i = 0; i < semMapEntries; i++)
for (i = 0; i < maxBackends; i++)
{
IpcSemaphoreId semId;
PROC *proc;
semId = IpcSemaphoreCreate(PROC_NSEMS_PER_SET,
IPCProtection,
1,
false);
ProcGlobal->procSemMap[i].procSemId = semId;
proc = (PROC *) ShmemAlloc(sizeof(PROC));
if (!proc)
elog(FATAL, "cannot create new proc: out of memory");
MemSet(proc, 0, sizeof(PROC));
PGSemaphoreCreate(&proc->sem);
proc->links.next = ProcGlobal->freeProcs;
ProcGlobal->freeProcs = MAKE_OFFSET(proc);
}
/*
* Pre-allocate a PROC structure for dummy (checkpoint) processes,
* and reserve the last sema of the precreated semas for it.
* too. This does not get linked into the freeProcs list.
*/
DummyProc = (PROC *) ShmemAlloc(sizeof(PROC));
if (!DummyProc)
elog(FATAL, "cannot create new proc: out of memory");
MemSet(DummyProc, 0, sizeof(PROC));
DummyProc->pid = 0; /* marks DummyProc as not in use */
i = semMapEntries - 1;
ProcGlobal->procSemMap[i].freeSemMap |= 1 << (PROC_NSEMS_PER_SET - 1);
DummyProc->sem.semId = ProcGlobal->procSemMap[i].procSemId;
DummyProc->sem.semNum = PROC_NSEMS_PER_SET - 1;
PGSemaphoreCreate(&DummyProc->sem);
/* Create ProcStructLock spinlock, too */
ProcStructLock = (slock_t *) ShmemAlloc(sizeof(slock_t));
@ -197,7 +162,7 @@ InitProcGlobal(int maxBackends)
}
/*
* InitProcess -- create a per-process data structure for this backend
* InitProcess -- initialize a per-process data structure for this backend
*/
void
InitProcess(void)
@ -217,7 +182,8 @@ InitProcess(void)
elog(ERROR, "InitProcess: you already exist");
/*
* try to get a proc struct from the free list first
* Try to get a proc struct from the free list. If this fails,
* we must be out of PROC structures (not to mention semaphores).
*/
SpinLockAcquire(ProcStructLock);
@ -232,20 +198,19 @@ InitProcess(void)
else
{
/*
* have to allocate a new one.
* If we reach here, all the PROCs are in use. This is one of
* the possible places to detect "too many backends", so give the
* standard error message.
*/
SpinLockRelease(ProcStructLock);
MyProc = (PROC *) ShmemAlloc(sizeof(PROC));
if (!MyProc)
elog(FATAL, "cannot create new proc: out of memory");
elog(FATAL, "Sorry, too many clients already");
}
/*
* Initialize all fields of MyProc.
* Initialize all fields of MyProc, except for the semaphore which
* was prepared for us by InitProcGlobal.
*/
SHMQueueElemInit(&(MyProc->links));
MyProc->sem.semId = -1; /* no wait-semaphore acquired yet */
MyProc->sem.semNum = -1;
MyProc->errType = STATUS_OK;
MyProc->xid = InvalidTransactionId;
MyProc->xmin = InvalidTransactionId;
@ -264,19 +229,11 @@ InitProcess(void)
*/
on_shmem_exit(ProcKill, 0);
/*
* Set up a wait-semaphore for the proc. (We rely on ProcKill to
* clean up MyProc if this fails.)
*/
if (IsUnderPostmaster)
ProcGetNewSemIdAndNum(&MyProc->sem.semId, &MyProc->sem.semNum);
/*
* We might be reusing a semaphore that belonged to a failed process.
* So be careful and reinitialize its value here.
*/
if (MyProc->sem.semId >= 0)
ZeroProcSemaphore(MyProc);
PGSemaphoreReset(&MyProc->sem);
/*
* Now that we have a PROC, we could try to acquire locks, so
@ -340,25 +297,7 @@ InitDummyProcess(void)
* We might be reusing a semaphore that belonged to a failed process.
* So be careful and reinitialize its value here.
*/
if (MyProc->sem.semId >= 0)
ZeroProcSemaphore(MyProc);
}
/*
* Initialize the proc's wait-semaphore to count zero.
*/
static void
ZeroProcSemaphore(PROC *proc)
{
union semun semun;
semun.val = 0;
if (semctl(proc->sem.semId, proc->sem.semNum, SETVAL, semun) < 0)
{
fprintf(stderr, "ZeroProcSemaphore: semctl(id=%d,SETVAL) failed: %s\n",
proc->sem.semId, strerror(errno));
proc_exit(255);
}
PGSemaphoreReset(&MyProc->sem);
}
/*
@ -397,7 +336,7 @@ LockWaitCancel(void)
* to zero. Otherwise, our next attempt to wait for a lock will fall
* through prematurely.
*/
ZeroProcSemaphore(MyProc);
PGSemaphoreReset(&MyProc->sem);
/*
* Return true even if we were kicked off the lock before we were able
@ -463,11 +402,7 @@ ProcKill(void)
SpinLockAcquire(ProcStructLock);
/* Free up my wait semaphore, if I got one */
if (MyProc->sem.semId >= 0)
ProcFreeSem(MyProc->sem.semId, MyProc->sem.semNum);
/* Add PROC struct to freelist so space can be recycled in future */
/* Return PROC structure (and semaphore) to freelist */
MyProc->links.next = procglobal->freeProcs;
procglobal->freeProcs = MAKE_OFFSET(MyProc);
@ -701,10 +636,10 @@ ProcSleep(LOCKMETHODTABLE *lockMethodTable,
elog(FATAL, "ProcSleep: Unable to set timer for process wakeup");
/*
* If someone wakes us between LWLockRelease and IpcSemaphoreLock,
* IpcSemaphoreLock will not block. The wakeup is "saved" by the
* If someone wakes us between LWLockRelease and PGSemaphoreLock,
* PGSemaphoreLock will not block. The wakeup is "saved" by the
* semaphore implementation. Note also that if HandleDeadLock is
* invoked but does not detect a deadlock, IpcSemaphoreLock() will
* invoked but does not detect a deadlock, PGSemaphoreLock() will
* continue to wait. There used to be a loop here, but it was useless
* code...
*
@ -714,7 +649,7 @@ ProcSleep(LOCKMETHODTABLE *lockMethodTable,
* here. We don't, because we have no state-change work to do after
* being granted the lock (the grantor did it all).
*/
IpcSemaphoreLock(MyProc->sem.semId, MyProc->sem.semNum, true);
PGSemaphoreLock(&MyProc->sem, true);
/*
* Disable the timer, if it's still running
@ -775,7 +710,7 @@ ProcWakeup(PROC *proc, int errType)
proc->errType = errType;
/* And awaken it */
IpcSemaphoreUnlock(proc->sem.semId, proc->sem.semNum);
PGSemaphoreUnlock(&proc->sem);
return retProc;
}
@ -914,7 +849,7 @@ HandleDeadLock(SIGNAL_ARGS)
* Unlock my semaphore so that the interrupted ProcSleep() call can
* finish.
*/
IpcSemaphoreUnlock(MyProc->sem.semId, MyProc->sem.semNum);
PGSemaphoreUnlock(&MyProc->sem);
/*
* We're done here. Transaction abort caused by the error that
@ -943,7 +878,7 @@ void
ProcWaitForSignal(void)
{
waitingForSignal = true;
IpcSemaphoreLock(MyProc->sem.semId, MyProc->sem.semNum, true);
PGSemaphoreLock(&MyProc->sem, true);
waitingForSignal = false;
}
@ -957,7 +892,7 @@ ProcWaitForSignal(void)
void
ProcCancelWaitForSignal(void)
{
ZeroProcSemaphore(MyProc);
PGSemaphoreReset(&MyProc->sem);
waitingForSignal = false;
}
@ -970,7 +905,7 @@ ProcSendSignal(BackendId procId)
PROC *proc = BackendIdGetProc(procId);
if (proc != NULL)
IpcSemaphoreUnlock(proc->sem.semId, proc->sem.semNum);
PGSemaphoreUnlock(&proc->sem);
}
@ -1035,110 +970,3 @@ disable_sigalrm_interrupt(void)
return true;
}
/*****************************************************************************
*
*****************************************************************************/
/*
* ProcGetNewSemIdAndNum -
* scan the free semaphore bitmap and allocate a single semaphore from
* a semaphore set.
*/
static void
ProcGetNewSemIdAndNum(IpcSemaphoreId *semId, int *semNum)
{
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
int semMapEntries = procglobal->semMapEntries;
volatile SEM_MAP_ENTRY *procSemMap = procglobal->procSemMap;
int32 fullmask = (1 << PROC_NSEMS_PER_SET) - 1;
int i;
SpinLockAcquire(ProcStructLock);
for (i = 0; i < semMapEntries; i++)
{
int mask = 1;
int j;
if (procSemMap[i].freeSemMap == fullmask)
continue; /* this set is fully allocated */
if (procSemMap[i].procSemId < 0)
continue; /* this set hasn't been initialized */
for (j = 0; j < PROC_NSEMS_PER_SET; j++)
{
if ((procSemMap[i].freeSemMap & mask) == 0)
{
/* A free semaphore found. Mark it as allocated. */
procSemMap[i].freeSemMap |= mask;
*semId = procSemMap[i].procSemId;
*semNum = j;
SpinLockRelease(ProcStructLock);
return;
}
mask <<= 1;
}
}
SpinLockRelease(ProcStructLock);
/*
* If we reach here, all the semaphores are in use. This is one of
* the possible places to detect "too many backends", so give the
* standard error message. (Whether we detect it here or in sinval.c
* depends on whether MaxBackends is a multiple of
* PROC_NSEMS_PER_SET.)
*/
elog(FATAL, "Sorry, too many clients already");
}
/*
* ProcFreeSem -
* free up our semaphore in the semaphore set.
*
* Caller is assumed to hold ProcStructLock.
*/
static void
ProcFreeSem(IpcSemaphoreId semId, int semNum)
{
int32 mask;
int i;
int semMapEntries = ProcGlobal->semMapEntries;
mask = ~(1 << semNum);
for (i = 0; i < semMapEntries; i++)
{
if (ProcGlobal->procSemMap[i].procSemId == semId)
{
ProcGlobal->procSemMap[i].freeSemMap &= mask;
return;
}
}
/* can't elog here!!! */
fprintf(stderr, "ProcFreeSem: no ProcGlobal entry for semId %d\n", semId);
}
/*
* ProcFreeAllSemaphores -
* called at shmem_exit time, ie when exiting the postmaster or
* destroying shared state for a failed set of backends.
* Free up all the semaphores allocated to the lmgrs of the backends.
*/
static void
ProcFreeAllSemaphores(void)
{
int i;
for (i = 0; i < ProcGlobal->semMapEntries; i++)
{
if (ProcGlobal->procSemMap[i].procSemId >= 0)
IpcSemaphoreKill(ProcGlobal->procSemMap[i].procSemId);
}
}

143
src/backend/storage/lmgr/spin.c
View File

@ -6,7 +6,8 @@
*
* For machines that have test-and-set (TAS) instructions, s_lock.h/.c
* define the spinlock implementation. This file contains only a stub
* implementation for spinlocks using SysV semaphores. The semaphore method
* implementation for spinlocks using PGSemaphores. Unless semaphores
* are implemented in a way that doesn't involve a kernel call, this
* is too slow to be very useful :-(
*
*
@ -15,143 +16,49 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/spin.c,v 1.7 2001/11/05 17:46:28 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/spin.c,v 1.8 2002/05/05 00:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <errno.h>
#include "storage/ipc.h"
/* In Ultrix, sem.h and shm.h must be included AFTER ipc.h */
#ifdef HAVE_SYS_SEM_H
#include <sys/sem.h>
#endif
#if defined(__darwin__)
#include "port/darwin/sem.h"
#endif
#include "storage/lwlock.h"
#include "storage/proc.h"
#include "storage/pg_sema.h"
#include "storage/spin.h"
#ifdef HAS_TEST_AND_SET
/*
* CreateSpinlocks --- create and initialize spinlocks during startup
* Report number of semaphores needed to support spinlocks.
*/
void
CreateSpinlocks(void)
int
SpinlockSemas(void)
{
/* no-op when we have TAS spinlocks */
return 0;
}
#else /* !HAS_TEST_AND_SET */
/*
* No TAS, so spinlocks are implemented using SysV semaphores.
*
* Typedef slock_t stores the semId and sem number of the sema to use.
* The semas needed are created by CreateSpinlocks and doled out by
* s_init_lock_sema.
*
* Since many systems have a rather small SEMMSL limit on semas per set,
* we allocate the semaphores required in sets of SPINLOCKS_PER_SET semas.
* This value is deliberately made equal to PROC_NSEMS_PER_SET so that all
* sema sets allocated by Postgres will be the same size; that eases the
* semaphore-recycling logic in IpcSemaphoreCreate().
*
* Note that the SpinLockIds array is not in shared memory; it is filled
* by the postmaster and then inherited through fork() by backends. This
* is OK because its contents do not change after shmem initialization.
* No TAS, so spinlocks are implemented as PGSemaphores.
*/
#define SPINLOCKS_PER_SET PROC_NSEMS_PER_SET
static IpcSemaphoreId *SpinLockIds = NULL;
static int numSpinSets = 0; /* number of sema sets used */
static int numSpinLocks = 0; /* total number of semas allocated */
static int nextSpinLock = 0; /* next free spinlock index */
static void SpinFreeAllSemaphores(void);
/*
* CreateSpinlocks --- create and initialize spinlocks during startup
* Report number of semaphores needed to support spinlocks.
*/
void
CreateSpinlocks(void)
int
SpinlockSemas(void)
{
int i;
if (SpinLockIds == NULL)
{
/*
* Compute number of spinlocks needed. It would be cleaner to
* distribute this logic into the affected modules, similar to the
* way shmem space estimation is handled.
*
* For now, though, we just need a few spinlocks (10 should be
* plenty) plus one for each LWLock.
*/
numSpinLocks = NumLWLocks() + 10;
/* might as well round up to a multiple of SPINLOCKS_PER_SET */
numSpinSets = (numSpinLocks - 1) / SPINLOCKS_PER_SET + 1;
numSpinLocks = numSpinSets * SPINLOCKS_PER_SET;
SpinLockIds = (IpcSemaphoreId *)
malloc(numSpinSets * sizeof(IpcSemaphoreId));
Assert(SpinLockIds != NULL);
}
for (i = 0; i < numSpinSets; i++)
SpinLockIds[i] = -1;
/*
* Arrange to delete semas on exit --- set this up now so that we will
* clean up if allocation fails. We use our own freeproc, rather than
* IpcSemaphoreCreate's removeOnExit option, because we don't want to
* fill up the on_shmem_exit list with a separate entry for each
* semaphore set.
* It would be cleaner to distribute this logic into the affected modules,
* similar to the way shmem space estimation is handled.
*
* For now, though, we just need a few spinlocks (10 should be
* plenty) plus one for each LWLock.
*/
on_shmem_exit(SpinFreeAllSemaphores, 0);
/* Create sema sets and set all semas to count 1 */
for (i = 0; i < numSpinSets; i++)
{
SpinLockIds[i] = IpcSemaphoreCreate(SPINLOCKS_PER_SET,
IPCProtection,
1,
false);
}
/* Init counter for allocating dynamic spinlocks */
nextSpinLock = 0;
}
/*
* SpinFreeAllSemaphores -
* called at shmem_exit time, ie when exiting the postmaster or
* destroying shared state for a failed set of backends.
* Free up all the semaphores allocated for spinlocks.
*/
static void
SpinFreeAllSemaphores(void)
{
int i;
for (i = 0; i < numSpinSets; i++)
{
if (SpinLockIds[i] >= 0)
IpcSemaphoreKill(SpinLockIds[i]);
}
free(SpinLockIds);
SpinLockIds = NULL;
return NumLWLocks() + 10;
}
/*
@ -161,30 +68,28 @@ SpinFreeAllSemaphores(void)
void
s_init_lock_sema(volatile slock_t *lock)
{
if (nextSpinLock >= numSpinLocks)
elog(FATAL, "s_init_lock_sema: not enough semaphores");
lock->semId = SpinLockIds[nextSpinLock / SPINLOCKS_PER_SET];
lock->sem = nextSpinLock % SPINLOCKS_PER_SET;
nextSpinLock++;
PGSemaphoreCreate((PGSemaphore) lock);
}
void
s_unlock_sema(volatile slock_t *lock)
{
IpcSemaphoreUnlock(lock->semId, lock->sem);
PGSemaphoreUnlock((PGSemaphore) lock);
}
bool
s_lock_free_sema(volatile slock_t *lock)
{
return IpcSemaphoreGetValue(lock->semId, lock->sem) > 0;
/* We don't currently use S_LOCK_FREE anyway */
elog(ERROR, "spin.c does not support S_LOCK_FREE()");
return false;
}
int
tas_sema(volatile slock_t *lock)
{
/* Note that TAS macros return 0 if *success* */
return !IpcSemaphoreTryLock(lock->semId, lock->sem);
return !PGSemaphoreTryLock((PGSemaphore) lock);
}
#endif /* !HAS_TEST_AND_SET */

7
src/backend/tcop/postgres.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.262 2002/04/20 21:56:15 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.263 2002/05/05 00:03:28 tgl Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@ -49,11 +49,12 @@
#include "parser/parse.h"
#include "parser/parser.h"
#include "rewrite/rewriteHandler.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "tcop/fastpath.h"
#include "tcop/pquery.h"
#include "tcop/tcopprot.h"
#include "tcop/utility.h"
#include "storage/proc.h"
#include "utils/exc.h"
#include "utils/guc.h"
#include "utils/memutils.h"
@ -1692,7 +1693,7 @@ PostgresMain(int argc, char *argv[], const char *username)
if (!IsUnderPostmaster)
{
puts("\nPOSTGRES backend interactive interface ");
puts("$Revision: 1.262 $ $Date: 2002/04/20 21:56:15 $\n");
puts("$Revision: 1.263 $ $Date: 2002/05/05 00:03:28 $\n");
}
/*

3
src/backend/utils/error/elog.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/error/elog.c,v 1.96 2002/04/21 00:22:52 ishii Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/error/elog.c,v 1.97 2002/05/05 00:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -30,6 +30,7 @@
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "tcop/tcopprot.h"
#include "utils/memutils.h"

26
src/backend/utils/init/miscinit.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.88 2002/05/03 20:43:30 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.89 2002/05/05 00:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -32,6 +32,8 @@
#include "catalog/pg_shadow.h"
#include "libpq/libpq-be.h"
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/pg_shmem.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
@ -819,25 +821,24 @@ CreateLockFile(const char *filename, bool amPostmaster,
if (isDDLock)
{
char *ptr;
unsigned long shmKey,
shmId;
unsigned long id1,
id2;
ptr = strchr(buffer, '\n');
if (ptr != NULL &&
(ptr = strchr(ptr + 1, '\n')) != NULL)
{
ptr++;
if (sscanf(ptr, "%lu %lu", &shmKey, &shmId) == 2)
if (sscanf(ptr, "%lu %lu", &id1, &id2) == 2)
{
if (SharedMemoryIsInUse((IpcMemoryKey) shmKey,
(IpcMemoryId) shmId))
if (PGSharedMemoryIsInUse(id1, id2))
{
fprintf(stderr,
"Found a pre-existing shared memory block (ID %d) still in use.\n"
"Found a pre-existing shared memory block (key %lu, id %lu) still in use.\n"
"If you're sure there are no old backends still running,\n"
"remove the shared memory block with ipcrm(1), or just\n"
"delete \"%s\".\n",
(int) shmId, filename);
id1, id2, filename);
return false;
}
}
@ -941,11 +942,11 @@ TouchSocketLockFile(void)
* This may be called multiple times in the life of a postmaster, if we
* delete and recreate shmem due to backend crash. Therefore, be prepared
* to overwrite existing information. (As of 7.1, a postmaster only creates
* one shm seg anyway; but for the purposes here, if we did have more than
* one shm seg at a time; but for the purposes here, if we did have more than
* one then any one of them would do anyway.)
*/
void
RecordSharedMemoryInLockFile(IpcMemoryKey shmKey, IpcMemoryId shmId)
RecordSharedMemoryInLockFile(unsigned long id1, unsigned long id2)
{
int fd;
int len;
@ -988,11 +989,10 @@ RecordSharedMemoryInLockFile(IpcMemoryKey shmKey, IpcMemoryId shmId)
ptr++;
/*
* Append shm key and ID. Format to try to keep it the same length
* Append key information. Format to try to keep it the same length
* always (trailing junk won't hurt, but might confuse humans).
*/
sprintf(ptr, "%9lu %9lu\n",
(unsigned long) shmKey, (unsigned long) shmId);
sprintf(ptr, "%9lu %9lu\n", id1, id2);
/*
* And rewrite the data. Since we write in a single kernel call, this

5
src/backend/utils/init/postinit.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.103 2002/04/27 21:24:34 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.104 2002/05/05 00:03:29 tgl Exp $
*
*
*-------------------------------------------------------------------------
@ -32,6 +32,7 @@
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "storage/backendid.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "storage/sinval.h"
#include "storage/smgr.h"
@ -181,7 +182,7 @@ InitCommunication(void)
* postmaster. Create private "shmem" and semaphores. Setting
* MaxBackends = 16 is arbitrary.
*/
CreateSharedMemoryAndSemaphores(true, 16);
CreateSharedMemoryAndSemaphores(true, 16, 0);
}
}

9
src/include/miscadmin.h
View File

@ -12,7 +12,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: miscadmin.h,v 1.102 2002/04/04 04:25:51 momjian Exp $
* $Id: miscadmin.h,v 1.103 2002/05/05 00:03:29 tgl Exp $
*
* NOTES
* some of the information in this file should be moved to
@ -23,7 +23,8 @@
#ifndef MISCADMIN_H
#define MISCADMIN_H
#include "storage/ipc.h"
#include <sys/types.h>
/*****************************************************************************
* System interrupt and critical section handling
@ -291,8 +292,8 @@ extern void BaseInit(void);
extern bool CreateDataDirLockFile(const char *datadir, bool amPostmaster);
extern bool CreateSocketLockFile(const char *socketfile, bool amPostmaster);
extern void TouchSocketLockFile(void);
extern void RecordSharedMemoryInLockFile(IpcMemoryKey shmKey,
IpcMemoryId shmId);
extern void RecordSharedMemoryInLockFile(unsigned long id1,
unsigned long id2);
extern void ValidatePgVersion(const char *path);

11
src/include/pg_config.h.in
View File

@ -8,7 +8,7 @@
* or in pg_config.h afterwards. Of course, if you edit pg_config.h, then your
* changes will be overwritten the next time you run configure.
*
* $Id: pg_config.h.in,v 1.23 2002/04/21 19:48:19 thomas Exp $
* $Id: pg_config.h.in,v 1.24 2002/05/05 00:03:29 tgl Exp $
*/
#ifndef PG_CONFIG_H
@ -711,6 +711,15 @@ extern int fdatasync(int fildes);
/* Define if you have syslog() */
#undef HAVE_SYSLOG
/* Define exactly one of these symbols to select semaphore implementation */
#undef USE_NAMED_POSIX_SEMAPHORES
#undef USE_UNNAMED_POSIX_SEMAPHORES
#undef USE_SYSV_SEMAPHORES
/* Define exactly one of these symbols to select shared-mem implementation */
#undef USE_SYSV_SHARED_MEMORY
/*
*------------------------------------------------------------------------
* Part 4: pull in system-specific declarations.

71
src/include/storage/ipc.h
View File

@ -3,63 +3,21 @@
* ipc.h
* POSTGRES inter-process communication definitions.
*
* This file is misnamed, as it no longer has much of anything directly
* to do with IPC. The functionality here is concerned with managing
* exit-time cleanup for either a postmaster or a backend.
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: ipc.h,v 1.54 2001/11/05 17:46:35 momjian Exp $
* $Id: ipc.h,v 1.55 2002/05/05 00:03:29 tgl Exp $
*
* Some files that would normally need to include only sys/ipc.h must
* instead include this file because on Ultrix, sys/ipc.h is not designed
* to be included multiple times. This file (by virtue of the ifndef IPC_H)
* is.
*-------------------------------------------------------------------------
*/
#ifndef IPC_H
#define IPC_H
#include <sys/types.h>
#ifdef HAVE_SYS_IPC_H
#include <sys/ipc.h>
#endif /* HAVE_SYS_IPC_H */
#ifndef HAVE_UNION_SEMUN
union semun
{
int val;
struct semid_ds *buf;
unsigned short *array;
};
#endif
/* generic IPC definitions */
#define IPCProtection (0600) /* access/modify by user only */
/* semaphore definitions */
typedef uint32 IpcSemaphoreKey; /* semaphore key passed to semget(2) */
typedef int IpcSemaphoreId; /* semaphore ID returned by semget(2) */
#define IPC_NMAXSEM 32 /* maximum number of semaphores per semID */
#define PGSemaMagic 537 /* must be less than SEMVMX */
/* shared memory definitions */
typedef uint32 IpcMemoryKey; /* shared memory key passed to shmget(2) */
typedef int IpcMemoryId; /* shared memory ID returned by shmget(2) */
typedef struct PGShmemHeader /* standard header for all Postgres shmem */
{
int32 magic; /* magic # to identify Postgres segments */
#define PGShmemMagic 679834892
pid_t creatorPID; /* PID of creating process */
uint32 totalsize; /* total size of segment */
uint32 freeoffset; /* offset to first free space */
} PGShmemHeader;
/* ipc.c */
extern bool proc_exit_inprogress;
@ -70,24 +28,9 @@ extern void on_proc_exit(void (*function) (), Datum arg);
extern void on_shmem_exit(void (*function) (), Datum arg);
extern void on_exit_reset(void);
extern void IpcInitKeyAssignment(int port);
extern IpcSemaphoreId IpcSemaphoreCreate(int numSems, int permission,
int semStartValue,
bool removeOnExit);
extern void IpcSemaphoreKill(IpcSemaphoreId semId);
extern void IpcSemaphoreLock(IpcSemaphoreId semId, int sem, bool interruptOK);
extern void IpcSemaphoreUnlock(IpcSemaphoreId semId, int sem);
extern bool IpcSemaphoreTryLock(IpcSemaphoreId semId, int sem);
extern int IpcSemaphoreGetValue(IpcSemaphoreId semId, int sem);
extern PGShmemHeader *IpcMemoryCreate(uint32 size, bool makePrivate,
int permission);
extern bool SharedMemoryIsInUse(IpcMemoryKey shmKey, IpcMemoryId shmId);
/* ipci.c */
extern void CreateSharedMemoryAndSemaphores(bool makePrivate,
int maxBackends);
int maxBackends,
int port);
#endif /* IPC_H */

76
src/include/storage/pg_sema.h Normal file
View File

@ -0,0 +1,76 @@
/*-------------------------------------------------------------------------
*
* pg_sema.h
* Platform-independent API for semaphores.
*
* PostgreSQL requires counting semaphores (the kind that keep track of
* multiple unlock operations, and will allow an equal number of subsequent
* lock operations before blocking). The underlying implementation is
* not the same on every platform. This file defines the API that must
* be provided by each port.
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: pg_sema.h,v 1.1 2002/05/05 00:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef PG_SEMA_H
#define PG_SEMA_H
/*
* PGSemaphoreData and pointer type PGSemaphore are the data structure
* representing an individual semaphore. The contents of PGSemaphoreData
* vary across implementations and must never be touched by platform-
* independent code. PGSemaphoreData structures are always allocated
* in shared memory (to support implementations where the data changes during
* lock/unlock).
*
* pg_config.h must define exactly one of the USE_xxx_SEMAPHORES symbols.
*/
#ifdef USE_NAMED_POSIX_SEMAPHORES
#include <semaphore.h>
typedef sem_t *PGSemaphoreData;
#endif
#ifdef USE_UNNAMED_POSIX_SEMAPHORES
#include <semaphore.h>
typedef sem_t PGSemaphoreData;
#endif
#ifdef USE_SYSV_SEMAPHORES
typedef struct PGSemaphoreData
{
int semId; /* semaphore set identifier */
int semNum; /* semaphore number within set */
} PGSemaphoreData;
#endif
typedef PGSemaphoreData *PGSemaphore;
/* Module initialization (called during postmaster start or shmem reinit) */
extern void PGReserveSemaphores(int maxSemas, int port);
/* Initialize a PGSemaphore structure to represent a sema with count 1 */
extern void PGSemaphoreCreate(PGSemaphore sema);
/* Reset a previously-initialized PGSemaphore to have count 0 */
extern void PGSemaphoreReset(PGSemaphore sema);
/* Lock a semaphore (decrement count), blocking if count would be < 0 */
extern void PGSemaphoreLock(PGSemaphore sema, bool interruptOK);
/* Unlock a semaphore (increment count) */
extern void PGSemaphoreUnlock(PGSemaphore sema);
/* Lock a semaphore only if able to do so without blocking */
extern bool PGSemaphoreTryLock(PGSemaphore sema);
#endif /* PG_SEMA_H */

44
src/include/storage/pg_shmem.h Normal file
View File

@ -0,0 +1,44 @@
/*-------------------------------------------------------------------------
*
* pg_shmem.h
* Platform-independent API for shared memory support.
*
* Every port is expected to support shared memory with approximately
* SysV-ish semantics; in particular, a memory block is not anonymous
* but has an ID, and we must be able to tell whether there are any
* remaining processes attached to a block of a specified ID.
*
* To simplify life for the SysV implementation, the ID is assumed to
* consist of two unsigned long values (these are key and ID in SysV
* terms). Other platforms may ignore the second value if they need
* only one ID number.
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: pg_shmem.h,v 1.1 2002/05/05 00:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef PG_SHMEM_H
#define PG_SHMEM_H
#include <sys/types.h>
typedef struct PGShmemHeader /* standard header for all Postgres shmem */
{
int32 magic; /* magic # to identify Postgres segments */
#define PGShmemMagic 679834892
pid_t creatorPID; /* PID of creating process */
uint32 totalsize; /* total size of segment */
uint32 freeoffset; /* offset to first free space */
} PGShmemHeader;
extern PGShmemHeader *PGSharedMemoryCreate(uint32 size, bool makePrivate,
int port);
extern bool PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2);
#endif /* PG_SHMEM_H */

49
src/include/storage/proc.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: proc.h,v 1.54 2001/11/06 00:38:26 tgl Exp $
* $Id: proc.h,v 1.55 2002/05/05 00:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -16,16 +16,10 @@
#include "access/xlog.h"
#include "storage/backendid.h"
#include "storage/ipc.h"
#include "storage/lock.h"
#include "storage/pg_sema.h"
typedef struct
{
IpcSemaphoreId semId; /* SysV semaphore set ID */
int semNum; /* semaphore number within set */
} SEMA;
/*
* Each backend has a PROC struct in shared memory. There is also a list of
* currently-unused PROC structs that will be reallocated to new backends.
@ -39,7 +33,7 @@ struct PROC
/* proc->links MUST BE FIRST IN STRUCT (see ProcSleep,ProcWakeup,etc) */
SHM_QUEUE links; /* list link if process is in a list */
SEMA sem; /* ONE semaphore to sleep on */
PGSemaphoreData sem; /* ONE semaphore to sleep on */
int errType; /* STATUS_OK or STATUS_ERROR after wakeup */
TransactionId xid; /* transaction currently being executed by
@ -84,47 +78,11 @@ extern PROC *MyProc;
/*
* There is one ProcGlobal struct for the whole installation.
*
* PROC_NSEMS_PER_SET is the number of semaphores in each sys-V semaphore set
* we allocate. It must be no more than 32 (or however many bits in an int
* on your machine), or our free-semaphores bitmap won't work. It also must
* be *less than* your kernel's SEMMSL (max semaphores per set) parameter,
* which is often around 25. (Less than, because we allocate one extra sema
* in each set for identification purposes.)
*
* PROC_SEM_MAP_ENTRIES is the number of semaphore sets we need to allocate
* to keep track of up to maxBackends backends. Note that we need one extra
* semaphore (see storage/lmgr/proc.c), so the computation may look wrong,
* but it's right.
*/
#define PROC_NSEMS_PER_SET 16
#define PROC_SEM_MAP_ENTRIES(maxBackends) ((maxBackends)/PROC_NSEMS_PER_SET+1)
typedef struct
{
/* info about a single set of per-process semaphores */
IpcSemaphoreId procSemId;
int32 freeSemMap;
/*
* In freeSemMap, bit i is set if the i'th semaphore of this sema set
* is allocated to a process. (i counts from 0 at the LSB)
*/
} SEM_MAP_ENTRY;
typedef struct PROC_HDR
{
/* Head of list of free PROC structures */
SHMEM_OFFSET freeProcs;
/* Info about semaphore sets used for per-process semaphores */
int semMapEntries;
/*
* VARIABLE LENGTH ARRAY: actual length is semMapEntries. THIS MUST BE
* LAST IN THE STRUCT DECLARATION.
*/
SEM_MAP_ENTRY procSemMap[1];
} PROC_HDR;
@ -135,6 +93,7 @@ extern int DeadlockTimeout;
/*
* Function Prototypes
*/
extern int ProcGlobalSemas(int maxBackends);
extern void InitProcGlobal(int maxBackends);
extern void InitProcess(void);
extern void InitDummyProcess(void);

15
src/include/storage/s_lock.h
View File

@ -63,14 +63,14 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: s_lock.h,v 1.97 2002/01/29 15:44:42 tgl Exp $
* $Id: s_lock.h,v 1.98 2002/05/05 00:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef S_LOCK_H
#define S_LOCK_H
#include "storage/ipc.h"
#include "storage/pg_sema.h"
#if defined(HAS_TEST_AND_SET)
@ -438,7 +438,6 @@ extern slock_t wc_tas(volatile slock_t *lock);
* AIX (POWER)
*
* Note that slock_t on POWER/POWER2/PowerPC is int instead of char
* (see storage/ipc.h).
*/
#define TAS(lock) cs((int *) (lock), 0, 1)
#endif /* _AIX */
@ -462,17 +461,11 @@ extern slock_t wc_tas(volatile slock_t *lock);
#else /* !HAS_TEST_AND_SET */
/*
* Fake spinlock implementation using SysV semaphores --- slow and prone
* Fake spinlock implementation using semaphores --- slow and prone
* to fall foul of kernel limits on number of semaphores, so don't use this
* unless you must! The subroutines appear in spin.c.
*/
typedef struct
{
/* reference to semaphore used to implement this spinlock */
IpcSemaphoreId semId;
int sem;
} slock_t;
typedef PGSemaphoreData slock_t;
extern bool s_lock_free_sema(volatile slock_t *lock);
extern void s_unlock_sema(volatile slock_t *lock);

4
src/include/storage/spin.h
View File

@ -40,7 +40,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: spin.h,v 1.19 2001/11/05 17:46:35 momjian Exp $
* $Id: spin.h,v 1.20 2002/05/05 00:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -72,6 +72,6 @@
#define SpinLockFree(lock) S_LOCK_FREE(lock)
extern void CreateSpinlocks(void);
extern int SpinlockSemas(void);
#endif /* SPIN_H */

16
src/pl/plperl/SPI.xs
View File

@ -21,22 +21,6 @@
#include "catalog/pg_type.h"
/* perl stuff */
/*
* Evil Code Alert
*
* both posgreSQL and perl try to do 'the right thing'
* and provide union semun if the platform doesn't define
* it in a system header.
* psql uses HAVE_UNION_SEMUN
* perl uses HAS_UNION_SEMUN
* together, they cause compile errors.
* If we need it, the psql headers above will provide it.
* So we tell perl that we have it.
*/
#ifndef HAS_UNION_SEMUN
#define HAS_UNION_SEMUN
#endif
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

18
src/pl/plperl/plperl.c
View File

@ -33,7 +33,7 @@
* ENHANCEMENTS, OR MODIFICATIONS.
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/pl/plperl/plperl.c,v 1.29 2002/03/06 18:50:26 momjian Exp $
* $Header: /cvsroot/pgsql/src/pl/plperl/plperl.c,v 1.30 2002/05/05 00:03:29 tgl Exp $
*
**********************************************************************/
@ -62,22 +62,6 @@
#include "catalog/pg_type.h"
/* perl stuff */
/*
* Evil Code Alert
*
* both posgreSQL and perl try to do 'the right thing'
* and provide union semun if the platform doesn't define
* it in a system header.
* psql uses HAVE_UNION_SEMUN
* perl uses HAS_UNION_SEMUN
* together, they cause compile errors.
* If we need it, the psql headers above will provide it.
* So we tell perl that we have it.
*/
#ifndef HAS_UNION_SEMUN
#define HAS_UNION_SEMUN
#endif
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

3
src/template/darwin
View File

@ -1,3 +1,6 @@
# -traditional-cpp means "don't use apple's cpp-precomp" on darwin
# this should change to -no-cpp-precomp when that flag is implemented
CC="$CC -traditional-cpp"
# Select appropriate semaphore support
USE_NAMED_POSIX_SEMAPHORES=1