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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1999
* Sleepycat Software. All rights reserved.
*/
#include "db_config.h"
#ifdef HAVE_MUTEX_PTHREAD
#ifndef lint
static const char sccsid[] = "@(#)mut_pthread.c 11.15 (Sleepycat) 11/9/99";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#endif
#include "db_int.h"
#ifdef DIAGNOSTIC
#undef MSG1
#define MSG1 "mutex_lock: ERROR: lock currently in use: pid: %lu.\n"
#undef MSG2
#define MSG2 "mutex_unlock: ERROR: lock already unlocked\n"
#ifndef STDERR_FILENO
#define STDERR_FILENO 2
#endif
#endif
#ifdef HAVE_MUTEX_SOLARIS_LWP
#define pthread_cond_signal _lwp_cond_signal
#define pthread_cond_wait _lwp_cond_wait
#define pthread_mutex_lock _lwp_mutex_lock
#define pthread_mutex_trylock _lwp_mutex_trylock
#define pthread_mutex_unlock _lwp_mutex_unlock
#endif
#ifdef HAVE_MUTEX_UI_THREADS
#define pthread_cond_signal cond_signal
#define pthread_cond_wait cond_wait
#define pthread_mutex_lock mutex_lock
#define pthread_mutex_trylock mutex_trylock
#define pthread_mutex_unlock mutex_unlock
#endif
/*
* CDB___db_pthread_mutex_init --
* Initialize a MUTEX.
*
* PUBLIC: int CDB___db_pthread_mutex_init __P((DB_ENV *, MUTEX *, u_int32_t));
*/
int
CDB___db_pthread_mutex_init(dbenv, mutexp, flags)
DB_ENV *dbenv;
MUTEX *mutexp;
u_int32_t flags;
{
int ret;
ret = 0;
memset(mutexp, 0, sizeof(*mutexp));
/*
* If this is a thread lock or the process has told us that there are
* no other processes in the environment, use thread-only locks, they
* are faster in some cases.
*
* This is where we decide to ignore locks we don't need to set -- if
* the application isn't threaded, there aren't any threads to block.
*/
if (LF_ISSET(MUTEX_THREAD) || F_ISSET(dbenv, DB_ENV_PRIVATE)) {
if (!F_ISSET(dbenv, DB_ENV_THREAD)) {
F_SET(mutexp, MUTEX_IGNORE);
return (0);
}
F_SET(mutexp, MUTEX_THREAD);
}
#ifdef HAVE_MUTEX_PTHREADS
{
pthread_condattr_t condattr, *condattrp = NULL;
pthread_mutexattr_t mutexattr, *mutexattrp = NULL;
if (!F_ISSET(mutexp, MUTEX_THREAD)) {
ret = pthread_condattr_init(&condattr);
if (ret == 0)
ret = pthread_condattr_setpshared(
&condattr, PTHREAD_PROCESS_SHARED);
condattrp = &condattr;
if (ret == 0)
ret = pthread_mutexattr_init(&mutexattr);
if (ret == 0)
ret = pthread_mutexattr_setpshared(
&mutexattr, PTHREAD_PROCESS_SHARED);
mutexattrp = &mutexattr;
}
if (ret == 0)
ret = pthread_mutex_init(&mutexp->mutex, mutexattrp);
if (mutexattrp != NULL)
pthread_mutexattr_destroy(mutexattrp);
if (LF_ISSET(MUTEX_SELF_BLOCK)) {
if (ret == 0)
ret = pthread_cond_init(&mutexp->cond, condattrp);
F_SET(mutexp, MUTEX_SELF_BLOCK);
if (condattrp != NULL)
pthread_condattr_destroy(condattrp);
}}
#endif
#ifdef HAVE_MUTEX_SOLARIS_LWP
if (F_ISSET(mutexp, MUTEX_THREAD)) {
static lwp_mutex_t mi = DEFAULTMUTEX;
/*
* !!!
* Gcc attempts to use special Sparc instructions to do a fast
* copy of the structures, but the structures aren't
* necessarily appropriately aligned for the Sparc instructions
* to work. We don't use memcpy instead of structure assignment
* because gcc figures that one out and drops core anyway.
*/
CDB___ua_memcpy(&mutexp->mutex, &mi, sizeof(mi));
} else {
static lwp_mutex_t mi = SHAREDMUTEX;
CDB___ua_memcpy(&mutexp->mutex, &mi, sizeof(mi));
}
if (LF_ISSET(MUTEX_SELF_BLOCK)) {
if (F_ISSET(mutexp, MUTEX_THREAD)) {
static lwp_cond_t ci = DEFAULTCV;
CDB___ua_memcpy(&mutexp->cond, &ci, sizeof(ci));
} else {
static lwp_cond_t ci = SHAREDCV;
CDB___ua_memcpy(&mutexp->cond, &ci, sizeof(ci));
}
F_SET(mutexp, MUTEX_SELF_BLOCK);
}
#endif
#ifdef HAVE_MUTEX_UI_THREADS
{
int type;
type = F_ISSET(mutexp, MUTEX_THREAD) ? USYNC_THREAD : USYNC_PROCESS;
ret = mutex_init(&mutexp->mutex, type, NULL);
if (ret == 0 && LF_ISSET(MUTEX_SELF_BLOCK)) {
ret = cond_init(&mutexp->cond, type, NULL);
F_SET(mutexp, MUTEX_SELF_BLOCK);
}}
#endif
mutexp->spins = CDB___os_spin();
return (ret);
}
/*
* CDB___db_pthread_mutex_lock
* Lock on a mutex, logically blocking if necessary.
*
* PUBLIC: int CDB___db_pthread_mutex_lock __P((MUTEX *));
*/
int
CDB___db_pthread_mutex_lock(mutexp)
MUTEX *mutexp;
{
u_int32_t nspins;
int ret, waited;
if (!DB_GLOBAL(db_mutexlocks) || F_ISSET(mutexp, MUTEX_IGNORE))
return (0);
/* Attempt to acquire the resource for N spins. */
for (nspins = mutexp->spins; nspins > 0; --nspins)
if (pthread_mutex_trylock(&mutexp->mutex) == 0)
break;
if (nspins == 0 && (ret = pthread_mutex_lock(&mutexp->mutex)) != 0)
return (ret);
if (F_ISSET(mutexp, MUTEX_SELF_BLOCK)) {
for (waited = 0; mutexp->locked != 0; waited = 1) {
ret = pthread_cond_wait(&mutexp->cond, &mutexp->mutex);
/*
* !!!
* Solaris bug workaround:
* pthread_cond_wait() sometimes returns ETIME -- out
* of sheer paranoia, check both ETIME and ETIMEDOUT.
* We believe this happens when the application uses
* SIGALRM for some purpose, e.g., the C library sleep
* call, and Solaris delivers the signal to the wrong
* LWP.
*/
if (ret != 0 &&
#ifdef ETIME
ret != ETIME &&
#endif
ret != ETIMEDOUT)
return (ret);
}
if (waited)
++mutexp->mutex_set_wait;
else
++mutexp->mutex_set_nowait;
#ifdef DIAGNOSTIC
mutexp->locked = (u_int32_t)pthread_self();
#else
mutexp->locked = 1;
#endif
if ((ret = pthread_mutex_unlock(&mutexp->mutex)) != 0)
return (ret);
} else {
if (nspins == mutexp->spins)
++mutexp->mutex_set_nowait;
else
++mutexp->mutex_set_wait;
#ifdef DIAGNOSTIC
if (mutexp->locked) {
char msgbuf[128];
(void)snprintf(msgbuf,
sizeof(msgbuf), MSG1, (u_long)mutexp->locked);
(void)write(STDERR_FILENO, msgbuf, strlen(msgbuf));
}
mutexp->locked = (u_int32_t)pthread_self();
#else
mutexp->locked = 1;
#endif
}
return (0);
}
/*
* CDB___db_pthread_mutex_unlock --
* Release a lock.
*
* PUBLIC: int CDB___db_pthread_mutex_unlock __P((MUTEX *));
*/
int
CDB___db_pthread_mutex_unlock(mutexp)
MUTEX *mutexp;
{
int ret;
if (!DB_GLOBAL(db_mutexlocks) || F_ISSET(mutexp, MUTEX_IGNORE))
return (0);
#ifdef DIAGNOSTIC
if (!mutexp->locked)
(void)write(STDERR_FILENO, MSG2, sizeof(MSG2) - 1);
#endif
if (F_ISSET(mutexp, MUTEX_SELF_BLOCK)) {
if ((ret = pthread_mutex_lock(&mutexp->mutex)) != 0)
return (ret);
mutexp->locked = 0;
if ((ret = pthread_mutex_unlock(&mutexp->mutex)) != 0)
return (ret);
if ((ret = pthread_cond_signal(&mutexp->cond)) != 0)
return (ret);
} else {
mutexp->locked = 0;
if ((ret = pthread_mutex_unlock(&mutexp->mutex)) != 0)
return (ret);
}
return (0);
}
#endif /* HAVE_MUTEX_PTHREAD */
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