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[svn-r14419] Description:

Browse Source 
Streamline threadsafety code to be simpler and reduce latency of holding
locks.

Tested on:
    Mac OS X/32 10.5.1 (amazon) w/threadsafe
This commit is contained in:
Quincey Koziol 2008-01-15 15:05:35 -05:00
parent 1e89b46eab
commit e4b251d90d
2 changed files with 21 additions and 34 deletions
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54
src/H5TS.c
View File

@ -96,10 +96,6 @@ H5TS_first_thread_init(void)
{
H5_g.H5_libinit_g = FALSE;
/* set the owner objects to initial values */
H5_g.init_lock.owner_thread = pthread_self();
H5_g.init_lock.owner_valid = FALSE;
/* initialize global API mutex lock */
pthread_mutex_init(&H5_g.init_lock.atomic_lock, NULL);
pthread_cond_init(&H5_g.init_lock.cond_var, NULL);
@ -150,26 +146,17 @@ H5TS_mutex_lock(H5TS_mutex_t *mutex)
if (ret_value)
return ret_value;
if (mutex->owner_valid && pthread_equal(pthread_self(), mutex->owner_thread)) {
if(mutex->lock_count && pthread_equal(pthread_self(), mutex->owner_thread)) {
/* already owned by self - increment count */
mutex->lock_count++;
} else if (!mutex->owner_valid) {
/* no one else has locked it - set owner and grab lock */
mutex->owner_thread = pthread_self();
mutex->owner_valid = TRUE;
mutex->lock_count = 1;
} else {
/* if already locked by someone else */
for (;;) {
pthread_cond_wait(&mutex->cond_var, &mutex->atomic_lock);
/* if owned by other thread, wait for condition signal */
while(mutex->lock_count)
pthread_cond_wait(&mutex->cond_var, &mutex->atomic_lock);
if (!mutex->owner_valid) {
mutex->owner_thread = pthread_self();
mutex->owner_valid = TRUE;
mutex->lock_count = 1;
break;
}
}
/* After we've received the signal, take ownership of the mutex */
mutex->owner_thread = pthread_self();
mutex->lock_count = 1;
}
return pthread_mutex_unlock(&mutex->atomic_lock);
@ -204,26 +191,27 @@ H5TS_mutex_lock(H5TS_mutex_t *mutex)
herr_t
H5TS_mutex_unlock(H5TS_mutex_t *mutex)
{
herr_t ret_value;
unsigned lock_count; /* Mutex's lock count */
herr_t ret_value; /* Return value */
ret_value = pthread_mutex_lock(&mutex->atomic_lock);
if (ret_value)
return ret_value;
if(ret_value)
return ret_value;
mutex->lock_count--;
lock_count = --mutex->lock_count;
if (mutex->lock_count == 0) {
mutex->owner_valid = FALSE;
ret_value = pthread_cond_signal(&mutex->cond_var);
ret_value = pthread_mutex_unlock(&mutex->atomic_lock);
if (ret_value) {
pthread_mutex_unlock(&mutex->atomic_lock);
return ret_value;
}
}
if(lock_count == 0) {
int err;
return pthread_mutex_unlock(&mutex->atomic_lock);
err = pthread_cond_signal(&mutex->cond_var);
if(err != 0)
ret_value = err;
} /* end if */
return ret_value;
}
/*--------------------------------------------------------------------------

1
src/H5TSprivate.h
View File

@ -37,7 +37,6 @@
typedef struct H5TS_mutex_struct {
pthread_t owner_thread; /* current lock owner */
unsigned owner_valid; /* if current lock owner info is valid */
pthread_mutex_t atomic_lock; /* lock for atomicity of new mechanism */
pthread_cond_t cond_var; /* condition variable */
unsigned int lock_count;