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/*-
* Copyright (c) 2008-2012 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
/*
* __wt_cond_alloc --
* Allocate and initialize a condition variable.
*/
int
__wt_cond_alloc(WT_SESSION_IMPL *session,
const char *name, int is_locked, WT_CONDVAR **condp)
{
WT_CONDVAR *cond;
/*
* !!!
* This function MUST handle a NULL session handle.
*/
WT_RET(__wt_calloc(session, 1, sizeof(WT_CONDVAR), &cond));
/* Initialize the mutex. */
if (pthread_mutex_init(&cond->mtx, NULL) != 0)
goto err;
/* Initialize the condition variable to permit self-blocking. */
if (pthread_cond_init(&cond->cond, NULL) != 0)
goto err;
cond->name = name;
cond->locked = is_locked;
*condp = cond;
return (0);
err: __wt_free(session, cond);
return (WT_ERROR);
}
/*
* __wt_lock
* Lock a mutex.
*/
void
__wt_cond_wait(WT_SESSION_IMPL *session, WT_CONDVAR *cond)
{
int ret;
/*
* !!!
* This function MUST handle a NULL session handle.
*/
if (session != NULL)
WT_VERBOSE(
session, mutex, "lock %s mutex (%p)", cond->name, cond);
WT_ERR(pthread_mutex_lock(&cond->mtx));
/*
* Check pthread_cond_wait() return for EINTR, ETIME and ETIMEDOUT,
* it's known to return these errors on some systems.
*/
while (cond->locked) {
ret = pthread_cond_wait(&cond->cond, &cond->mtx);
if (ret != 0 &&
ret != EINTR &&
#ifdef ETIME
ret != ETIME &&
#endif
ret != ETIMEDOUT) {
(void)pthread_mutex_unlock(&cond->mtx);
goto err;
}
}
cond->locked = 1;
if (session != NULL)
WT_CSTAT_INCR(session, cond_wait);
WT_ERR(pthread_mutex_unlock(&cond->mtx));
return;
err: __wt_err(session, ret, "mutex lock failed");
__wt_abort(session);
}
/*
* __wt_cond_signal --
* Signal a waiting thread.
*/
void
__wt_cond_signal(WT_SESSION_IMPL *session, WT_CONDVAR *cond)
{
int ret;
/*
* !!!
* This function MUST handle a NULL session handle.
*/
if (session != NULL)
WT_VERBOSE(
session, mutex, "signal %s cond (%p)", cond->name, cond);
ret = 0;
WT_ERR(pthread_mutex_lock(&cond->mtx));
if (cond->locked) {
cond->locked = 0;
WT_ERR(pthread_cond_signal(&cond->cond));
}
WT_ERR(pthread_mutex_unlock(&cond->mtx));
return;
err: __wt_err(session, ret, "mutex unlock failed");
__wt_abort(session);
}
/*
* __wt_cond_destroy --
* Destroy a condition variable.
*/
int
__wt_cond_destroy(WT_SESSION_IMPL *session, WT_CONDVAR *cond)
{
int ret;
ret = pthread_cond_destroy(&cond->cond);
WT_TRET(pthread_mutex_destroy(&cond->mtx));
__wt_free(session, cond);
return ((ret == 0) ? 0 : WT_ERROR);
}
/*
* __wt_rwlock_alloc --
* Allocate and initialize a read/write lock.
*/
int
__wt_rwlock_alloc(
WT_SESSION_IMPL *session, const char *name, WT_RWLOCK **rwlockp)
{
WT_RWLOCK *rwlock;
int ret;
WT_RET(__wt_calloc(session, 1, sizeof(WT_RWLOCK), &rwlock));
ret = 0;
WT_ERR_TEST(pthread_rwlock_init(&rwlock->rwlock, NULL), WT_ERROR);
rwlock->name = name;
*rwlockp = rwlock;
if (0) {
err: __wt_free(session, rwlock);
}
return (ret);
}
/*
* __wt_readlock
* Get a shared lock.
*/
void
__wt_readlock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock)
{
int ret;
WT_VERBOSE(session, mutex,
"readlock %s rwlock (%p)", rwlock->name, rwlock);
WT_ERR(pthread_rwlock_rdlock(&rwlock->rwlock));
WT_CSTAT_INCR(session, rwlock_rdlock);
if (0) {
err: __wt_err(session, ret, "rwlock readlock failed");
__wt_abort(session);
}
}
/*
* __wt_try_writelock
* Try to get an exclusive lock, or fail immediately if unavailable.
*/
int
__wt_try_writelock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock)
{
int ret;
WT_VERBOSE(session, mutex,
"try_writelock %s rwlock (%p)", rwlock->name, rwlock);
if ((ret = pthread_rwlock_trywrlock(&rwlock->rwlock)) == 0)
WT_CSTAT_INCR(session, rwlock_wrlock);
else if (ret != EBUSY) {
__wt_err(session, ret, "rwlock try_writelock failed");
__wt_abort(session);
}
return (ret);
}
/*
* __wt_writelock
* Wait to get an exclusive lock.
*/
void
__wt_writelock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock)
{
int ret;
WT_VERBOSE(session, mutex,
"writelock %s rwlock (%p)", rwlock->name, rwlock);
WT_ERR(pthread_rwlock_wrlock(&rwlock->rwlock));
WT_CSTAT_INCR(session, rwlock_wrlock);
if (0) {
err: __wt_err(session, ret, "rwlock writelock failed");
__wt_abort(session);
}
}
/*
* __wt_rwunlock --
* Release a read/write lock.
*/
void
__wt_rwunlock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock)
{
int ret;
WT_VERBOSE(session, mutex,
"unlock %s rwlock (%p)", rwlock->name, rwlock);
WT_ERR(pthread_rwlock_unlock(&rwlock->rwlock));
if (0) {
err: __wt_err(session, ret, "rwlock unlock failed");
__wt_abort(session);
}
}
/*
* __wt_rwlock_destroy --
* Destroy a mutex.
*/
int
__wt_rwlock_destroy(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock)
{
int ret;
ret = pthread_rwlock_destroy(&rwlock->rwlock);
if (ret == EBUSY)
ret = 0;
WT_ASSERT(session, ret == 0);
__wt_free(session, rwlock);
return (ret);
}
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