131 lines
3.0 KiB
C
131 lines
3.0 KiB
C
#include <minix/mthread.h>
|
|
#include "global.h"
|
|
|
|
/*===========================================================================*
|
|
* mthread_rwlock_init *
|
|
*===========================================================================*/
|
|
int mthread_rwlock_init(rwlock)
|
|
mthread_rwlock_t *rwlock; /* The rwlock to be initialized */
|
|
{
|
|
/* Initialize a readers/writer lock. */
|
|
int r;
|
|
|
|
if (!rwlock)
|
|
return EINVAL;
|
|
|
|
rwlock->writer = NO_THREAD;
|
|
rwlock->readers = 0;
|
|
|
|
r = mthread_mutex_init(&rwlock->queue, NULL);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
r = mthread_event_init(&rwlock->drain);
|
|
if (r != 0)
|
|
mthread_mutex_destroy(&rwlock->queue);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* mthread_rwlock_destroy *
|
|
*===========================================================================*/
|
|
int mthread_rwlock_destroy(rwlock)
|
|
mthread_rwlock_t *rwlock; /* The rwlock to be destroyed */
|
|
{
|
|
/* Destroy a readers/writer lock. */
|
|
int r;
|
|
|
|
if (!rwlock)
|
|
return EINVAL;
|
|
|
|
assert(rwlock->writer == NO_THREAD);
|
|
assert(rwlock->readers == 0);
|
|
|
|
r = mthread_event_destroy(&rwlock->drain);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
return mthread_mutex_destroy(&rwlock->queue);
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* mthread_rwlock_rdlock *
|
|
*===========================================================================*/
|
|
int mthread_rwlock_rdlock(rwlock)
|
|
mthread_rwlock_t *rwlock; /* The rwlock to be read locked */
|
|
{
|
|
/* Acquire a reader lock. */
|
|
int r;
|
|
|
|
if (!rwlock)
|
|
return EINVAL;
|
|
|
|
r = mthread_mutex_lock(&rwlock->queue);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
r = mthread_mutex_unlock(&rwlock->queue);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
rwlock->readers++;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* mthread_rwlock_wrlock *
|
|
*===========================================================================*/
|
|
int mthread_rwlock_wrlock(rwlock)
|
|
mthread_rwlock_t *rwlock; /* The rwlock to be write locked */
|
|
{
|
|
/* Acquire a writer lock. */
|
|
int r;
|
|
|
|
if (!rwlock)
|
|
return EINVAL;
|
|
|
|
r = mthread_mutex_lock(&rwlock->queue);
|
|
if (r != 0)
|
|
return r;
|
|
|
|
rwlock->writer = current_thread;
|
|
|
|
if (rwlock->readers > 0)
|
|
r = mthread_event_wait(&rwlock->drain);
|
|
|
|
if (r == 0)
|
|
assert(rwlock->readers == 0);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* mthread_rwlock_unlock *
|
|
*===========================================================================*/
|
|
int mthread_rwlock_unlock(rwlock)
|
|
mthread_rwlock_t *rwlock; /* The rwlock to be unlocked */
|
|
{
|
|
/* Release a lock. */
|
|
int r;
|
|
|
|
r = 0;
|
|
if (!rwlock)
|
|
return EINVAL;
|
|
|
|
if (rwlock->writer == current_thread) {
|
|
rwlock->writer = NO_THREAD;
|
|
r = mthread_mutex_unlock(&rwlock->queue);
|
|
} else {
|
|
assert(rwlock->readers > 0);
|
|
|
|
rwlock->readers--;
|
|
|
|
if (rwlock->readers == 0 && rwlock->writer != NO_THREAD)
|
|
r = mthread_event_fire(&rwlock->drain);
|
|
}
|
|
|
|
return r;
|
|
}
|