diff options
Diffstat (limited to 'src/backend/storage')
| -rw-r--r-- | src/backend/storage/file/fd.c | 3 | ||||
| -rw-r--r-- | src/backend/storage/ipc/ipc.c | 812 | ||||
| -rw-r--r-- | src/backend/storage/ipc/ipci.c | 18 | ||||
| -rw-r--r-- | src/backend/storage/ipc/shmem.c | 3 | ||||
| -rw-r--r-- | src/backend/storage/ipc/sinvaladt.c | 3 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/lwlock.c | 8 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/proc.c | 296 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/spin.c | 143 |
8 files changed, 116 insertions, 1170 deletions
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c index 8726a394599..473c5318d31 100644 --- a/src/backend/storage/file/fd.c +++ b/src/backend/storage/file/fd.c @@ -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 */ diff --git a/src/backend/storage/ipc/ipc.c b/src/backend/storage/ipc/ipc.c index 10d3d6e7edb..fad78835416 100644 --- a/src/backend/storage/ipc/ipc.c +++ b/src/backend/storage/ipc/ipc.c @@ -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; -} diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index c2950dc767a..34412e3ed44 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -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 diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c index f9056ae375b..3b558f528fa 100644 --- a/src/backend/storage/ipc/shmem.c +++ b/src/backend/storage/ipc/shmem.c @@ -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" diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index bae8983472d..dbe75469d06 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -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" diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c index e85ef7ea11a..8dbf55c0788 100644 --- a/src/backend/storage/lmgr/lwlock.c +++ b/src/backend/storage/lmgr/lwlock.c @@ -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); } /* diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index 99825529558..8ccaff94776 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -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. - */ - on_shmem_exit(ProcFreeAllSemaphores, 0); /* - * Pre-create the semaphores. + * Pre-create the PROC structures and create a semaphore for each. */ - for (i = 0; i < semMapEntries; i++) + for (i = 0; i < maxBackends; i++) { - IpcSemaphoreId semId; - - semId = IpcSemaphoreCreate(PROC_NSEMS_PER_SET, - IPCProtection, - 1, - false); - ProcGlobal->procSemMap[i].procSemId = semId; + PROC *proc; + + 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; @@ -265,18 +230,10 @@ 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); - } -} diff --git a/src/backend/storage/lmgr/spin.c b/src/backend/storage/lmgr/spin.c index f5bb8e34889..c384c4b1586 100644 --- a/src/backend/storage/lmgr/spin.c +++ b/src/backend/storage/lmgr/spin.c @@ -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 */ |