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982 lines
32 KiB
C
982 lines
32 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1996-2004
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* Sleepycat Software. All rights reserved.
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*
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* $Id: mutex.h,v 11.100 2004/10/05 14:41:12 mjc Exp $
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*/
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#ifndef _DB_MUTEX_H_
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#define _DB_MUTEX_H_
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/*
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* Some of the Berkeley DB ports require single-threading at various
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* places in the code. In those cases, these #defines will be set.
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*/
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#define DB_BEGIN_SINGLE_THREAD
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#define DB_END_SINGLE_THREAD
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/*********************************************************************
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* POSIX.1 pthreads interface.
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*********************************************************************/
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#ifdef HAVE_MUTEX_PTHREADS
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#include <pthread.h>
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#define MUTEX_FIELDS \
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pthread_mutex_t mutex; /* Mutex. */ \
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pthread_cond_t cond; /* Condition variable. */
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#endif
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/*********************************************************************
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* Solaris lwp threads interface.
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*
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* !!!
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* We use LWP mutexes on Solaris instead of UI or POSIX mutexes (both of
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* which are available), for two reasons. First, the Solaris C library
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* includes versions of the both UI and POSIX thread mutex interfaces, but
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* they are broken in that they don't support inter-process locking, and
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* there's no way to detect it, e.g., calls to configure the mutexes for
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* inter-process locking succeed without error. So, we use LWP mutexes so
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* that we don't fail in fairly undetectable ways because the application
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* wasn't linked with the appropriate threads library. Second, there were
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* bugs in SunOS 5.7 (Solaris 7) where if an application loaded the C library
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* before loading the libthread/libpthread threads libraries (e.g., by using
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* dlopen to load the DB library), the pwrite64 interface would be translated
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* into a call to pwrite and DB would drop core.
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*********************************************************************/
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#ifdef HAVE_MUTEX_SOLARIS_LWP
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/*
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* XXX
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* Don't change <synch.h> to <sys/lwp.h> -- although lwp.h is listed in the
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* Solaris manual page as the correct include to use, it causes the Solaris
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* compiler on SunOS 2.6 to fail.
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*/
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#include <synch.h>
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#define MUTEX_FIELDS \
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lwp_mutex_t mutex; /* Mutex. */ \
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lwp_cond_t cond; /* Condition variable. */
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#endif
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/*********************************************************************
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* Solaris/Unixware threads interface.
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*********************************************************************/
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#ifdef HAVE_MUTEX_UI_THREADS
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#include <thread.h>
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#include <synch.h>
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#define MUTEX_FIELDS \
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mutex_t mutex; /* Mutex. */ \
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cond_t cond; /* Condition variable. */
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#endif
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/*********************************************************************
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* AIX C library functions.
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*********************************************************************/
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#ifdef HAVE_MUTEX_AIX_CHECK_LOCK
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#include <sys/atomic_op.h>
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typedef int tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_INIT(x) 0
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#define MUTEX_SET(x) (!_check_lock(x, 0, 1))
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#define MUTEX_UNSET(x) _clear_lock(x, 0)
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#endif
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#endif
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/*********************************************************************
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* Apple/Darwin library functions.
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*********************************************************************/
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#ifdef HAVE_MUTEX_DARWIN_SPIN_LOCK_TRY
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typedef u_int32_t tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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extern int _spin_lock_try(tsl_t *);
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extern void _spin_unlock(tsl_t *);
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#define MUTEX_SET(tsl) _spin_lock_try(tsl)
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#define MUTEX_UNSET(tsl) _spin_unlock(tsl)
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#define MUTEX_INIT(tsl) (MUTEX_UNSET(tsl), 0)
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#endif
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#endif
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/*********************************************************************
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* General C library functions (msemaphore).
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*
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* !!!
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* Check for HPPA as a special case, because it requires unusual alignment,
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* and doesn't support semaphores in malloc(3) or shmget(2) memory.
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*
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* !!!
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* Do not remove the MSEM_IF_NOWAIT flag. The problem is that if a single
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* process makes two msem_lock() calls in a row, the second one returns an
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* error. We depend on the fact that we can lock against ourselves in the
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* locking subsystem, where we set up a mutex so that we can block ourselves.
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* Tested on OSF1 v4.0.
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*********************************************************************/
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#ifdef HAVE_MUTEX_HPPA_MSEM_INIT
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#define MUTEX_NO_MALLOC_LOCKS
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#define MUTEX_NO_SHMGET_LOCKS
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN 16
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#define HPUX_MUTEX_PAD 8
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#endif
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#endif
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#if defined(HAVE_MUTEX_MSEM_INIT) || defined(HAVE_MUTEX_HPPA_MSEM_INIT)
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#include <sys/mman.h>
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typedef msemaphore tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_INIT(x) (msem_init(x, MSEM_UNLOCKED) <= (msemaphore *)0)
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#define MUTEX_SET(x) (!msem_lock(x, MSEM_IF_NOWAIT))
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#define MUTEX_UNSET(x) msem_unlock(x, 0)
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#endif
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#endif
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/*********************************************************************
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* Plan 9 library functions.
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*********************************************************************/
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#ifdef HAVE_MUTEX_PLAN9
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typedef Lock tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(int)
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#endif
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#define MUTEX_INIT(x) (memset(x, 0, sizeof(Lock)), 0)
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#define MUTEX_SET(x) canlock(x)
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#define MUTEX_UNSET(x) unlock(x)
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#endif
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/*********************************************************************
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* Reliant UNIX C library functions.
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*********************************************************************/
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#ifdef HAVE_MUTEX_RELIANTUNIX_INITSPIN
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#include <ulocks.h>
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typedef spinlock_t tsl_t;
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_INIT(x) (initspin(x, 1), 0)
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#define MUTEX_SET(x) (cspinlock(x) == 0)
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#define MUTEX_UNSET(x) spinunlock(x)
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#endif
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#endif
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/*********************************************************************
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* General C library functions (POSIX 1003.1 sema_XXX).
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*
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* !!!
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* Never selected by autoconfig in this release (semaphore calls are known
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* to not work in Solaris 5.5).
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*********************************************************************/
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#ifdef HAVE_MUTEX_SEMA_INIT
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#include <synch.h>
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typedef sema_t tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_DESTROY(x) sema_destroy(x)
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#define MUTEX_INIT(x) (sema_init(x, 1, USYNC_PROCESS, NULL) != 0)
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#define MUTEX_SET(x) (sema_wait(x) == 0)
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#define MUTEX_UNSET(x) sema_post(x)
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#endif
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#endif
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/*********************************************************************
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* SGI C library functions.
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*********************************************************************/
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#ifdef HAVE_MUTEX_SGI_INIT_LOCK
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#include <abi_mutex.h>
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typedef abilock_t tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_INIT(x) (init_lock(x) != 0)
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#define MUTEX_SET(x) (!acquire_lock(x))
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#define MUTEX_UNSET(x) release_lock(x)
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#endif
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#endif
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/*********************************************************************
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* Solaris C library functions.
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*
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* !!!
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* These are undocumented functions, but they're the only ones that work
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* correctly as far as we know.
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*********************************************************************/
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#ifdef HAVE_MUTEX_SOLARIS_LOCK_TRY
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#include <sys/machlock.h>
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typedef lock_t tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_INIT(x) 0
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#define MUTEX_SET(x) _lock_try(x)
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#define MUTEX_UNSET(x) _lock_clear(x)
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#endif
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#endif
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/*********************************************************************
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* VMS.
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*********************************************************************/
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#ifdef HAVE_MUTEX_VMS
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#include <sys/mman.h>;
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#include <builtins.h>
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typedef volatile unsigned char tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(unsigned int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#ifdef __ALPHA
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#define MUTEX_SET(tsl) (!__TESTBITSSI(tsl, 0))
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#else /* __VAX */
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#define MUTEX_SET(tsl) (!(int)_BBSSI(0, tsl))
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#endif
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#define MUTEX_UNSET(tsl) (*(tsl) = 0)
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#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
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#endif
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#endif
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/*********************************************************************
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* VxWorks
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* Use basic binary semaphores in VxWorks, as we currently do not need
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* any special features. We do need the ability to single-thread the
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* entire system, however, because VxWorks doesn't support the open(2)
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* flag O_EXCL, the mechanism we normally use to single thread access
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* when we're first looking for a DB environment.
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*********************************************************************/
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#ifdef HAVE_MUTEX_VXWORKS
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#include "taskLib.h"
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typedef SEM_ID tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(unsigned int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_SET(tsl) (semTake((*tsl), WAIT_FOREVER) == OK)
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#define MUTEX_UNSET(tsl) (semGive((*tsl)))
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#define MUTEX_INIT(tsl) \
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((*(tsl) = semBCreate(SEM_Q_FIFO, SEM_FULL)) == NULL)
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#define MUTEX_DESTROY(tsl) semDelete(*tsl)
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#endif
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/*
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* Use the taskLock() mutex to eliminate a race where two tasks are
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* trying to initialize the global lock at the same time.
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*/
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#undef DB_BEGIN_SINGLE_THREAD
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#define DB_BEGIN_SINGLE_THREAD do { \
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if (DB_GLOBAL(db_global_init)) \
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(void)semTake(DB_GLOBAL(db_global_lock), WAIT_FOREVER); \
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else { \
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taskLock(); \
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if (DB_GLOBAL(db_global_init)) { \
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taskUnlock(); \
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(void)semTake(DB_GLOBAL(db_global_lock), \
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WAIT_FOREVER); \
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continue; \
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} \
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DB_GLOBAL(db_global_lock) = \
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semBCreate(SEM_Q_FIFO, SEM_EMPTY); \
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if (DB_GLOBAL(db_global_lock) != NULL) \
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DB_GLOBAL(db_global_init) = 1; \
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taskUnlock(); \
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} \
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} while (DB_GLOBAL(db_global_init) == 0)
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#undef DB_END_SINGLE_THREAD
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#define DB_END_SINGLE_THREAD (void)semGive(DB_GLOBAL(db_global_lock))
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#endif
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/*********************************************************************
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* Win16
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*
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* Win16 spinlocks are simple because we cannot possibly be preempted.
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*
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* !!!
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* We should simplify this by always returning a no-need-to-lock lock
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* when we initialize the mutex.
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*********************************************************************/
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#ifdef HAVE_MUTEX_WIN16
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typedef unsigned int tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN sizeof(unsigned int)
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_INIT(x) 0
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#define MUTEX_SET(tsl) (*(tsl) = 1)
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#define MUTEX_UNSET(tsl) (*(tsl) = 0)
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#endif
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#endif
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/*********************************************************************
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* Win32
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*********************************************************************/
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#if defined(HAVE_MUTEX_WIN32) || defined(HAVE_MUTEX_WIN32_GCC)
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#define MUTEX_FIELDS \
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LONG volatile tas; \
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LONG nwaiters; \
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u_int32_t id; /* ID used for creating events */ \
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#if defined(LOAD_ACTUAL_MUTEX_CODE)
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#define MUTEX_SET(tsl) (InterlockedExchange((PLONG)(tsl), 1) == 0)
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#define MUTEX_UNSET(tsl) (InterlockedExchange((PLONG)(tsl), 0))
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#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
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/*
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* From Intel's performance tuning documentation (and see SR #6975):
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* ftp://download.intel.com/design/perftool/cbts/appnotes/sse2/w_spinlock.pdf
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*
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* "For this reason, it is highly recommended that you insert the PAUSE
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* instruction into all spin-wait code immediately. Using the PAUSE
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* instruction does not affect the correctness of programs on existing
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* platforms, and it improves performance on Pentium 4 processor platforms."
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*/
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#ifdef HAVE_MUTEX_WIN32
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#ifndef _WIN64
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#define MUTEX_PAUSE {__asm{_emit 0xf3}; __asm{_emit 0x90}}
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#endif
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#endif
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#ifdef HAVE_MUTEX_WIN32_GCC
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#define MUTEX_PAUSE asm volatile ("rep; nop" : : );
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#endif
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#endif
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#endif
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/*********************************************************************
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* 68K/gcc assembly.
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*********************************************************************/
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#ifdef HAVE_MUTEX_68K_GCC_ASSEMBLY
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typedef unsigned char tsl_t;
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_SET_TEST 1 /* gcc/68K: 0 is clear, 1 is set. */
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#define MUTEX_SET(tsl) ({ \
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register tsl_t *__l = (tsl); \
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int __r; \
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asm volatile("tas %1; \n \
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seq %0" \
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: "=dm" (__r), "=m" (*__l) \
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: "1" (*__l) \
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); \
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__r & 1; \
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})
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#define MUTEX_UNSET(tsl) (*(tsl) = 0)
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#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
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#endif
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#endif
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/*********************************************************************
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* ALPHA/gcc assembly.
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*********************************************************************/
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#ifdef HAVE_MUTEX_ALPHA_GCC_ASSEMBLY
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typedef u_int32_t tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN 4
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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/*
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* For gcc/alpha. Should return 0 if could not acquire the lock, 1 if
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* lock was acquired properly.
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*/
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static inline int
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MUTEX_SET(tsl_t *tsl) {
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register tsl_t *__l = tsl;
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register tsl_t __r;
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asm volatile(
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"1: ldl_l %0,%2\n"
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" blbs %0,2f\n"
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" or $31,1,%0\n"
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" stl_c %0,%1\n"
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" beq %0,3f\n"
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" mb\n"
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" br 3f\n"
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"2: xor %0,%0\n"
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"3:"
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: "=&r"(__r), "=m"(*__l) : "1"(*__l) : "memory");
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return __r;
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}
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/*
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* Unset mutex. Judging by Alpha Architecture Handbook, the mb instruction
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* might be necessary before unlocking
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*/
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static inline int
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MUTEX_UNSET(tsl_t *tsl) {
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asm volatile(" mb\n");
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return *tsl = 0;
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}
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#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
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#endif
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#endif
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/*********************************************************************
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* Tru64/cc assembly.
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*********************************************************************/
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#ifdef HAVE_MUTEX_TRU64_CC_ASSEMBLY
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typedef volatile u_int32_t tsl_t;
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#ifndef MUTEX_ALIGN
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#define MUTEX_ALIGN 4
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#endif
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#include <alpha/builtins.h>
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#define MUTEX_SET(tsl) (__LOCK_LONG_RETRY((tsl), 1) != 0)
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#define MUTEX_UNSET(tsl) (__UNLOCK_LONG(tsl))
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#define MUTEX_INIT(tsl) (MUTEX_UNSET(tsl), 0)
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#endif
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#endif
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/*********************************************************************
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* ARM/gcc assembly.
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*********************************************************************/
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#ifdef HAVE_MUTEX_ARM_GCC_ASSEMBLY
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typedef unsigned char tsl_t;
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#ifdef LOAD_ACTUAL_MUTEX_CODE
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#define MUTEX_SET_TEST 1 /* gcc/arm: 0 is clear, 1 is set. */
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#define MUTEX_SET(tsl) ({ \
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int __r; \
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asm volatile( \
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"swpb %0, %1, [%2]\n\t" \
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"eor %0, %0, #1\n\t" \
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: "=&r" (__r) \
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: "r" (1), "r" (tsl) \
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); \
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__r & 1; \
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})
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#define MUTEX_UNSET(tsl) (*(volatile tsl_t *)(tsl) = 0)
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#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
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#endif
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#endif
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/*********************************************************************
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* HPPA/gcc assembly.
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*********************************************************************/
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#ifdef HAVE_MUTEX_HPPA_GCC_ASSEMBLY
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typedef u_int32_t tsl_t;
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|
|
#ifndef MUTEX_ALIGN
|
|
#define MUTEX_ALIGN 16
|
|
#define HPUX_MUTEX_PAD 8
|
|
#endif
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
/*
|
|
* The PA-RISC has a "load and clear" instead of a "test and set" instruction.
|
|
* The 32-bit word used by that instruction must be 16-byte aligned. We could
|
|
* use the "aligned" attribute in GCC but that doesn't work for stack variables.
|
|
*/
|
|
#define MUTEX_SET(tsl) ({ \
|
|
register tsl_t *__l = (tsl); \
|
|
int __r; \
|
|
asm volatile("ldcws 0(%1),%0" : "=r" (__r) : "r" (__l)); \
|
|
__r & 1; \
|
|
})
|
|
|
|
#define MUTEX_UNSET(tsl) (*(tsl) = -1)
|
|
#define MUTEX_INIT(tsl) (MUTEX_UNSET(tsl), 0)
|
|
#endif
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
* IA64/gcc assembly.
|
|
*********************************************************************/
|
|
#ifdef HAVE_MUTEX_IA64_GCC_ASSEMBLY
|
|
typedef unsigned char tsl_t;
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
#define MUTEX_SET_TEST 1 /* gcc/ia64: 0 is clear, 1 is set. */
|
|
|
|
#define MUTEX_SET(tsl) ({ \
|
|
register tsl_t *__l = (tsl); \
|
|
long __r; \
|
|
asm volatile("xchg1 %0=%1,%3" : "=r"(__r), "=m"(*__l) : "1"(*__l), "r"(1));\
|
|
__r ^ 1; \
|
|
})
|
|
|
|
/*
|
|
* Store through a "volatile" pointer so we get a store with "release"
|
|
* semantics.
|
|
*/
|
|
#define MUTEX_UNSET(tsl) (*(volatile unsigned char *)(tsl) = 0)
|
|
#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
|
|
#endif
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
* PowerPC/gcc assembly.
|
|
*********************************************************************/
|
|
#if defined(HAVE_MUTEX_PPC_GCC_ASSEMBLY)
|
|
typedef u_int32_t tsl_t;
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
/*
|
|
* The PowerPC does a sort of pseudo-atomic locking. You set up a
|
|
* 'reservation' on a chunk of memory containing a mutex by loading the
|
|
* mutex value with LWARX. If the mutex has an 'unlocked' (arbitrary)
|
|
* value, you then try storing into it with STWCX. If no other process or
|
|
* thread broke your 'reservation' by modifying the memory containing the
|
|
* mutex, then the STCWX succeeds; otherwise it fails and you try to get
|
|
* a reservation again.
|
|
*
|
|
* While mutexes are explicitly 4 bytes, a 'reservation' applies to an
|
|
* entire cache line, normally 32 bytes, aligned naturally. If the mutex
|
|
* lives near data that gets changed a lot, there's a chance that you'll
|
|
* see more broken reservations than you might otherwise. The only
|
|
* situation in which this might be a problem is if one processor is
|
|
* beating on a variable in the same cache block as the mutex while another
|
|
* processor tries to acquire the mutex. That's bad news regardless
|
|
* because of the way it bashes caches, but if you can't guarantee that a
|
|
* mutex will reside in a relatively quiescent cache line, you might
|
|
* consider padding the mutex to force it to live in a cache line by
|
|
* itself. No, you aren't guaranteed that cache lines are 32 bytes. Some
|
|
* embedded processors use 16-byte cache lines, while some 64-bit
|
|
* processors use 128-bit cache lines. But assuming a 32-byte cache line
|
|
* won't get you into trouble for now.
|
|
*
|
|
* If mutex locking is a bottleneck, then you can speed it up by adding a
|
|
* regular LWZ load before the LWARX load, so that you can test for the
|
|
* common case of a locked mutex without wasting cycles making a reservation.
|
|
*
|
|
* 'set' mutexes have the value 1, like on Intel; the returned value from
|
|
* MUTEX_SET() is 1 if the mutex previously had its low bit clear, 0 otherwise.
|
|
*/
|
|
#define MUTEX_SET_TEST 1 /* gcc/ppc: 0 is clear, 1 is set. */
|
|
|
|
static inline int
|
|
MUTEX_SET(int *tsl) {
|
|
int __r;
|
|
int __tmp = (int)tsl;
|
|
asm volatile (
|
|
"0: \n\t"
|
|
" lwarx %0,0,%2 \n\t"
|
|
" cmpwi %0,0 \n\t"
|
|
" bne- 1f \n\t"
|
|
" stwcx. %2,0,%2 \n\t"
|
|
" isync \n\t"
|
|
" beq+ 2f \n\t"
|
|
" b 0b \n\t"
|
|
"1: \n\t"
|
|
" li %1, 0 \n\t"
|
|
"2: \n\t"
|
|
: "=&r" (__r), "=r" (tsl)
|
|
: "r" (__tmp)
|
|
: "cr0", "memory");
|
|
return (int)tsl;
|
|
}
|
|
|
|
static inline int
|
|
MUTEX_UNSET(tsl_t *tsl) {
|
|
asm volatile("sync" : : : "memory");
|
|
return *tsl = 0;
|
|
}
|
|
#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
|
|
#endif
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
* OS/390 C
|
|
*********************************************************************/
|
|
#ifdef HAVE_MUTEX_S390_CC_ASSEMBLY
|
|
typedef int tsl_t;
|
|
|
|
#ifndef MUTEX_ALIGN
|
|
#define MUTEX_ALIGN sizeof(int)
|
|
#endif
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
/*
|
|
* cs() is declared in <stdlib.h> but is built in to the compiler.
|
|
* Must use LANGLVL(EXTENDED) to get its declaration.
|
|
*/
|
|
#define MUTEX_SET(tsl) (!cs(&zero, (tsl), 1))
|
|
#define MUTEX_UNSET(tsl) (*(tsl) = 0)
|
|
#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
|
|
#endif
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
* S/390 32-bit assembly.
|
|
*********************************************************************/
|
|
#ifdef HAVE_MUTEX_S390_GCC_ASSEMBLY
|
|
typedef int tsl_t;
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
#define MUTEX_SET_TEST 1 /* gcc/S390: 0 is clear, 1 is set. */
|
|
|
|
static inline int
|
|
MUTEX_SET(tsl_t *tsl) { \
|
|
register tsl_t *__l = (tsl); \
|
|
int __r; \
|
|
asm volatile( \
|
|
" la 1,%1\n" \
|
|
" lhi 0,1\n" \
|
|
" l %0,%1\n" \
|
|
"0: cs %0,0,0(1)\n" \
|
|
" jl 0b" \
|
|
: "=&d" (__r), "+m" (*__l) \
|
|
: : "0", "1", "cc"); \
|
|
return !__r; \
|
|
}
|
|
|
|
#define MUTEX_UNSET(tsl) (*(tsl) = 0)
|
|
#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
|
|
#endif
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
* SCO/cc assembly.
|
|
*********************************************************************/
|
|
#ifdef HAVE_MUTEX_SCO_X86_CC_ASSEMBLY
|
|
typedef unsigned char tsl_t;
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
/*
|
|
* UnixWare has threads in libthread, but OpenServer doesn't (yet).
|
|
*/
|
|
#define MUTEX_SET_TEST 1 /* cc/x86: 0 is clear, 1 is set. */
|
|
|
|
#if defined(__USLC__)
|
|
asm int
|
|
_tsl_set(void *tsl)
|
|
{
|
|
%mem tsl
|
|
movl tsl, %ecx
|
|
movl $1, %eax
|
|
lock
|
|
xchgb (%ecx),%al
|
|
xorl $1,%eax
|
|
}
|
|
#endif
|
|
|
|
#define MUTEX_SET(tsl) _tsl_set(tsl)
|
|
#define MUTEX_UNSET(tsl) (*(tsl) = 0)
|
|
#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
|
|
#endif
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
* Sparc/gcc assembly.
|
|
*********************************************************************/
|
|
#ifdef HAVE_MUTEX_SPARC_GCC_ASSEMBLY
|
|
typedef unsigned char tsl_t;
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
/*
|
|
*
|
|
* The ldstub instruction takes the location specified by its first argument
|
|
* (a register containing a memory address) and loads its contents into its
|
|
* second argument (a register) and atomically sets the contents the location
|
|
* specified by its first argument to a byte of 1s. (The value in the second
|
|
* argument is never read, but only overwritten.)
|
|
*
|
|
* The stbar is needed for v8, and is implemented as membar #sync on v9,
|
|
* so is functional there as well. For v7, stbar may generate an illegal
|
|
* instruction and we have no way to tell what we're running on. Some
|
|
* operating systems notice and skip this instruction in the fault handler.
|
|
*/
|
|
#define MUTEX_SET_TEST 1 /* gcc/sparc: 0 is clear, 1 is set. */
|
|
|
|
#define MUTEX_SET(tsl) ({ \
|
|
register tsl_t *__l = (tsl); \
|
|
register tsl_t __r; \
|
|
__asm__ volatile \
|
|
("ldstub [%1],%0; stbar" \
|
|
: "=r"( __r) : "r" (__l)); \
|
|
!__r; \
|
|
})
|
|
|
|
#define MUTEX_UNSET(tsl) (*(tsl) = 0)
|
|
#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
|
|
#endif
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
* UTS/cc assembly.
|
|
*********************************************************************/
|
|
#ifdef HAVE_MUTEX_UTS_CC_ASSEMBLY
|
|
typedef int tsl_t;
|
|
|
|
#ifndef MUTEX_ALIGN
|
|
#define MUTEX_ALIGN sizeof(int)
|
|
#endif
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
#define MUTEX_INIT(x) 0
|
|
#define MUTEX_SET(x) (!uts_lock(x, 1))
|
|
#define MUTEX_UNSET(x) (*(x) = 0)
|
|
#endif
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
* x86/gcc assembly.
|
|
*********************************************************************/
|
|
#ifdef HAVE_MUTEX_X86_GCC_ASSEMBLY
|
|
typedef unsigned char tsl_t;
|
|
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
#define MUTEX_SET_TEST 1 /* gcc/x86: 0 is clear, 1 is set. */
|
|
|
|
#define MUTEX_SET(tsl) ({ \
|
|
register tsl_t *__l = (tsl); \
|
|
int __r; \
|
|
asm volatile("movl $1,%%eax; lock; xchgb %1,%%al; xorl $1,%%eax"\
|
|
: "=&a" (__r), "=m" (*__l) \
|
|
: "1" (*__l) \
|
|
); \
|
|
__r & 1; \
|
|
})
|
|
|
|
#define MUTEX_UNSET(tsl) (*(tsl) = 0)
|
|
#define MUTEX_INIT(tsl) MUTEX_UNSET(tsl)
|
|
|
|
/*
|
|
* From Intel's performance tuning documentation (and see SR #6975):
|
|
* ftp://download.intel.com/design/perftool/cbts/appnotes/sse2/w_spinlock.pdf
|
|
*
|
|
* "For this reason, it is highly recommended that you insert the PAUSE
|
|
* instruction into all spin-wait code immediately. Using the PAUSE
|
|
* instruction does not affect the correctness of programs on existing
|
|
* platforms, and it improves performance on Pentium 4 processor platforms."
|
|
*/
|
|
#define MUTEX_PAUSE asm volatile ("rep; nop" : : );
|
|
#endif
|
|
#endif
|
|
|
|
/*
|
|
* Mutex alignment defaults to one byte.
|
|
*
|
|
* !!!
|
|
* Various systems require different alignments for mutexes (the worst we've
|
|
* seen so far is 16-bytes on some HP architectures). Malloc(3) is assumed
|
|
* to return reasonable alignment, all other mutex users must ensure proper
|
|
* alignment locally.
|
|
*/
|
|
#ifndef MUTEX_ALIGN
|
|
#define MUTEX_ALIGN 1
|
|
#endif
|
|
|
|
/*
|
|
* Mutex destruction defaults to a no-op.
|
|
*/
|
|
#ifdef LOAD_ACTUAL_MUTEX_CODE
|
|
#ifndef MUTEX_DESTROY
|
|
#define MUTEX_DESTROY(x)
|
|
#endif
|
|
#endif
|
|
|
|
/*
|
|
* !!!
|
|
* The flag arguments for __db_mutex_setup (and the underlying initialization
|
|
* function for the mutex type, for example, __db_tas_mutex_init), and flags
|
|
* stored in the DB_MUTEX structure are combined, and may not overlap. Flags
|
|
* to __db_mutex_setup:
|
|
*
|
|
* MUTEX_ALLOC:
|
|
* Use when the mutex to initialize needs to be allocated. The 'ptr'
|
|
* arg to __db_mutex_setup should be a DB_MUTEX ** whenever you use
|
|
* this flag. If this flag is not set, the 'ptr' arg is a DB_MUTEX *.
|
|
* MUTEX_NO_RECORD:
|
|
* Explicitly do not record the mutex in the region. Otherwise the
|
|
* mutex will be recorded by default. If you set this you need to
|
|
* understand why you don't need it recorded. The *only* ones not
|
|
* recorded are those that are part of region structures that only
|
|
* get destroyed when the regions are destroyed.
|
|
* MUTEX_NO_RLOCK:
|
|
* Explicitly do not lock the given region otherwise the region will
|
|
* be locked by default.
|
|
* MUTEX_SELF_BLOCK:
|
|
* Set if self blocking mutex.
|
|
* MUTEX_THREAD:
|
|
* Set if mutex is a thread-only mutex.
|
|
*/
|
|
#define MUTEX_ALLOC 0x0001 /* Allocate and init a mutex */
|
|
#define MUTEX_IGNORE 0x0002 /* Ignore, no lock required. */
|
|
#define MUTEX_INITED 0x0004 /* Mutex is successfully initialized */
|
|
#define MUTEX_LOGICAL_LOCK 0x0008 /* Mutex backs database lock. */
|
|
#define MUTEX_MPOOL 0x0010 /* Allocated from mpool. */
|
|
#define MUTEX_NO_RECORD 0x0020 /* Do not record lock */
|
|
#define MUTEX_NO_RLOCK 0x0040 /* Do not acquire region lock */
|
|
#define MUTEX_SELF_BLOCK 0x0080 /* Must block self. */
|
|
#define MUTEX_THREAD 0x0100 /* Thread-only mutex. */
|
|
|
|
/* Mutex. */
|
|
struct __mutex_t {
|
|
#ifdef HAVE_MUTEX_THREADS
|
|
#ifdef MUTEX_FIELDS
|
|
MUTEX_FIELDS
|
|
#else
|
|
tsl_t tas; /* Test and set. */
|
|
#endif
|
|
u_int32_t locked; /* !0 if locked. */
|
|
#else
|
|
u_int32_t off; /* Byte offset to lock. */
|
|
u_int32_t pid; /* Lock holder: 0 or process pid. */
|
|
#endif
|
|
u_int32_t mutex_set_wait; /* Granted after wait. */
|
|
u_int32_t mutex_set_nowait; /* Granted without waiting. */
|
|
u_int32_t mutex_set_spin; /* Granted without spinning. */
|
|
u_int32_t mutex_set_spins; /* Total number of spins. */
|
|
#ifdef HAVE_MUTEX_SYSTEM_RESOURCES
|
|
roff_t reg_off; /* Shared lock info offset. */
|
|
#endif
|
|
/*
|
|
* Flags should be an unsigned integer even if it's not required by
|
|
* the possible flags values, getting a single byte on some machines
|
|
* is expensive, and the mutex structure is a MP hot spot.
|
|
*/
|
|
u_int32_t flags; /* MUTEX_XXX */
|
|
};
|
|
|
|
/* Macro to clear mutex statistics. */
|
|
#define MUTEX_CLEAR(mp) { \
|
|
(mp)->mutex_set_wait = (mp)->mutex_set_nowait = 0; \
|
|
}
|
|
|
|
/* Redirect calls to the correct functions. */
|
|
#ifdef HAVE_MUTEX_THREADS
|
|
#if defined(HAVE_MUTEX_PTHREADS) || \
|
|
defined(HAVE_MUTEX_SOLARIS_LWP) || \
|
|
defined(HAVE_MUTEX_UI_THREADS)
|
|
#define __db_mutex_init_int(a, b, c, d) __db_pthread_mutex_init(a, b, d)
|
|
#define __db_mutex_lock(a, b) __db_pthread_mutex_lock(a, b)
|
|
#define __db_mutex_unlock(a, b) __db_pthread_mutex_unlock(a, b)
|
|
#define __db_mutex_destroy(a) __db_pthread_mutex_destroy(a)
|
|
#else
|
|
#if defined(HAVE_MUTEX_WIN32) || defined(HAVE_MUTEX_WIN32_GCC)
|
|
#define __db_mutex_init_int(a, b, c, d) __db_win32_mutex_init(a, b, d)
|
|
#define __db_mutex_lock(a, b) __db_win32_mutex_lock(a, b)
|
|
#define __db_mutex_unlock(a, b) __db_win32_mutex_unlock(a, b)
|
|
#define __db_mutex_destroy(a) __db_win32_mutex_destroy(a)
|
|
#else
|
|
#define __db_mutex_init_int(a, b, c, d) __db_tas_mutex_init(a, b, d)
|
|
#define __db_mutex_lock(a, b) __db_tas_mutex_lock(a, b)
|
|
#define __db_mutex_unlock(a, b) __db_tas_mutex_unlock(a, b)
|
|
#define __db_mutex_destroy(a) __db_tas_mutex_destroy(a)
|
|
#endif
|
|
#endif
|
|
#else
|
|
#define __db_mutex_init_int(a, b, c, d) __db_fcntl_mutex_init(a, b, c)
|
|
#define __db_mutex_lock(a, b) __db_fcntl_mutex_lock(a, b)
|
|
#define __db_mutex_unlock(a, b) __db_fcntl_mutex_unlock(a, b)
|
|
#define __db_mutex_destroy(a) __db_fcntl_mutex_destroy(a)
|
|
#endif
|
|
|
|
/* Redirect system resource calls to correct functions */
|
|
#ifdef HAVE_MUTEX_SYSTEM_RESOURCES
|
|
#define __db_maintinit(a, b, c) __db_shreg_maintinit(a, b, c)
|
|
#define __db_shlocks_clear(a, b, c) __db_shreg_locks_clear(a, b, c)
|
|
#define __db_shlocks_destroy(a, b) __db_shreg_locks_destroy(a, b)
|
|
#define __db_mutex_init(a, b, c, d, e, f) \
|
|
__db_shreg_mutex_init(a, b, c, d, e, f)
|
|
#else
|
|
#define __db_maintinit(a, b, c)
|
|
#define __db_shlocks_clear(a, b, c)
|
|
#define __db_shlocks_destroy(a, b)
|
|
#define __db_mutex_init(a, b, c, d, e, f) __db_mutex_init_int(a, b, c, d)
|
|
#endif
|
|
|
|
/*
|
|
* Lock/unlock a mutex. If the mutex was marked as uninteresting, the thread
|
|
* of control can proceed without it.
|
|
*
|
|
* If the lock is for threads-only, then it was optionally not allocated and
|
|
* file handles aren't necessary, as threaded applications aren't supported by
|
|
* fcntl(2) locking.
|
|
*/
|
|
#ifdef DIAGNOSTIC
|
|
/*
|
|
* XXX
|
|
* We want to switch threads as often as possible. Yield every time
|
|
* we get a mutex to ensure contention.
|
|
*/
|
|
#define MUTEX_LOCK(dbenv, mp) \
|
|
if (!F_ISSET((mp), MUTEX_IGNORE)) \
|
|
DB_ASSERT(__db_mutex_lock(dbenv, mp) == 0); \
|
|
if (F_ISSET(dbenv, DB_ENV_YIELDCPU)) \
|
|
__os_yield(NULL, 1);
|
|
#else
|
|
#define MUTEX_LOCK(dbenv, mp) \
|
|
if (!F_ISSET((mp), MUTEX_IGNORE)) \
|
|
(void)__db_mutex_lock(dbenv, mp);
|
|
#endif
|
|
#define MUTEX_UNLOCK(dbenv, mp) \
|
|
if (!F_ISSET((mp), MUTEX_IGNORE)) \
|
|
(void)__db_mutex_unlock(dbenv, mp);
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#define MUTEX_THREAD_LOCK(dbenv, mp) \
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if (mp != NULL) \
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MUTEX_LOCK(dbenv, mp)
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#define MUTEX_THREAD_UNLOCK(dbenv, mp) \
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if (mp != NULL) \
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MUTEX_UNLOCK(dbenv, mp)
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|
|
|
/*
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|
* We use a single file descriptor for fcntl(2) locking, and (generally) the
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|
* object's offset in a shared region as the byte that we're locking. So,
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|
* there's a (remote) possibility that two objects might have the same offsets
|
|
* such that the locks could conflict, resulting in deadlock. To avoid this
|
|
* possibility, we offset the region offset by a small integer value, using a
|
|
* different offset for each subsystem's locks. Since all region objects are
|
|
* suitably aligned, the offset guarantees that we don't collide with another
|
|
* region's objects.
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|
*/
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|
#define DB_FCNTL_OFF_GEN 0 /* Everything else. */
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|
#define DB_FCNTL_OFF_LOCK 1 /* Lock subsystem offset. */
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|
#define DB_FCNTL_OFF_MPOOL 2 /* Mpool subsystem offset. */
|
|
|
|
#ifdef HAVE_MUTEX_SYSTEM_RESOURCES
|
|
/*
|
|
* When the underlying mutexes require library (most likely heap) or system
|
|
* resources, we have to clean up when we discard mutexes (for the library
|
|
* resources) and both when discarding mutexes and after application failure
|
|
* (for the mutexes requiring system resources). This violates the rule that
|
|
* we never look at a shared region after application failure, but we've no
|
|
* other choice. In those cases, the #define HAVE_MUTEX_SYSTEM_RESOURCES is
|
|
* set.
|
|
*
|
|
* To support mutex release after application failure, allocate thread-handle
|
|
* mutexes in shared memory instead of in the heap. The number of slots we
|
|
* allocate for this purpose isn't configurable, but this tends to be an issue
|
|
* only on embedded systems where we don't expect large server applications.
|
|
*/
|
|
#define DB_MAX_HANDLES 100 /* Mutex slots for handles. */
|
|
#endif
|
|
#endif /* !_DB_MUTEX_H_ */
|