/* Acquire the rwlock *RWLOCK for reading blocking until *ABSTIME if
it is already held. As a GNU extension, if TIMESPEC is NULL then
wait forever. */
int
__pthread_rwlock_timedrdlock_internal (struct __pthread_rwlock *rwlock,
const struct timespec *abstime)
{
error_t err;
int drain;
struct __pthread *self;
__pthread_spin_lock (&rwlock->__lock);
if (__pthread_spin_trylock (&rwlock->__held) == 0)
/* Successfully acquired the lock. */
{
assert (rwlock->__readerqueue == 0);
assert (rwlock->__writerqueue == 0);
assert (rwlock->__readers == 0);
rwlock->__readers = 1;
__pthread_spin_unlock (&rwlock->__lock);
return 0;
}
else
/* Lock is held, but is held by a reader? */
if (rwlock->__readers > 0)
/* Just add ourself to number of readers. */
{
assert (rwlock->__readerqueue == 0);
rwlock->__readers++;
__pthread_spin_unlock (&rwlock->__lock);
return 0;
}
/* The lock is busy. */
/* Better be blocked by a writer. */
assert (rwlock->__readers == 0);
if (abstime != NULL && (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000))
return EINVAL;
self = _pthread_self ();
/* Add ourself to the queue. */
__pthread_enqueue (&rwlock->__readerqueue, self);
__pthread_spin_unlock (&rwlock->__lock);
/* Block the thread. */
if (abstime != NULL)
err = __pthread_timedblock (self, abstime, CLOCK_REALTIME);
else
{
err = 0;
__pthread_block (self);
}
__pthread_spin_lock (&rwlock->__lock);
if (self->prevp == NULL)
/* Another thread removed us from the queue, which means a wakeup message
has been sent. It was either consumed while we were blocking, or
queued after we timed out and before we acquired the rwlock lock, in
which case the message queue must be drained. */
drain = err ? 1 : 0;
else
{
/* We're still in the queue. Noone attempted to wake us up, i.e. we
timed out. */
__pthread_dequeue (self);
drain = 0;
}
__pthread_spin_unlock (&rwlock->__lock);
if (drain)
__pthread_block (self);
if (err)
{
assert (err == ETIMEDOUT);
return err;
}
/* The reader count has already been increment by whoever woke us
up. */
assert (rwlock->__readers > 0);
return 0;
}
/* Block on condition variable COND until ABSTIME. As a GNU
extension, if ABSTIME is NULL, then wait forever. MUTEX should be
held by the calling thread. On return, MUTEX will be held by the
calling thread. */
int
__pthread_cond_timedwait_internal (pthread_cond_t *cond,
pthread_mutex_t *mutex,
const struct timespec *abstime)
{
error_t err;
int cancelled, oldtype, drain;
clockid_t clock_id = __pthread_default_condattr.__clock;
if (abstime && (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000))
return EINVAL;
struct __pthread *self = _pthread_self ();
struct cancel_ctx ctx;
ctx.wakeup = self;
ctx.cond = cond;
/* Test for a pending cancellation request, switch to deferred mode for
safer resource handling, and prepare the hook to call in case we're
cancelled while blocking. Once CANCEL_LOCK is released, the cancellation
hook can be called by another thread at any time. Whatever happens,
this function must exit with MUTEX locked.
This function contains inline implementations of pthread_testcancel and
pthread_setcanceltype to reduce locking overhead. */
__pthread_mutex_lock (&self->cancel_lock);
cancelled = (self->cancel_state == PTHREAD_CANCEL_ENABLE)
&& self->cancel_pending;
if (!cancelled)
{
self->cancel_hook = cancel_hook;
self->cancel_hook_arg = &ctx;
oldtype = self->cancel_type;
if (oldtype != PTHREAD_CANCEL_DEFERRED)
self->cancel_type = PTHREAD_CANCEL_DEFERRED;
/* Add ourselves to the list of waiters. This is done while setting
the cancellation hook to simplify the cancellation procedure, i.e.
if the thread is queued, it can be cancelled, otherwise it is
already unblocked, progressing on the return path. */
__pthread_spin_lock (&cond->__lock);
__pthread_enqueue (&cond->__queue, self);
if (cond->__attr != NULL)
clock_id = cond->__attr->__clock;
__pthread_spin_unlock (&cond->__lock);
}
__pthread_mutex_unlock (&self->cancel_lock);
if (cancelled)
__pthread_exit (PTHREAD_CANCELED);
/* Release MUTEX before blocking. */
__pthread_mutex_unlock (mutex);
/* Block the thread. */
if (abstime != NULL)
err = __pthread_timedblock (self, abstime, clock_id);
else
{
err = 0;
__pthread_block (self);
}
__pthread_spin_lock (&cond->__lock);
if (self->prevp == NULL)
{
/* Another thread removed us from the list of waiters, which means a
wakeup message has been sent. It was either consumed while we were
blocking, or queued after we timed out and before we acquired the
condition lock, in which case the message queue must be drained. */
if (!err)
drain = 0;
else
{
assert (err == ETIMEDOUT);
drain = 1;
}
}
else
{
/* We're still in the list of waiters. Noone attempted to wake us up,
i.e. we timed out. */
assert (err == ETIMEDOUT);
__pthread_dequeue (self);
drain = 0;
}
__pthread_spin_unlock (&cond->__lock);
if (drain)
__pthread_block (self);
/* We're almost done. Remove the unblock hook, restore the previous
cancellation type, and check for a pending cancellation request. */
__pthread_mutex_lock (&self->cancel_lock);
self->cancel_hook = NULL;
self->cancel_hook_arg = NULL;
self->cancel_type = oldtype;
cancelled = (self->cancel_state == PTHREAD_CANCEL_ENABLE)
&& self->cancel_pending;
__pthread_mutex_unlock (&self->cancel_lock);
/* Reacquire MUTEX before returning/cancelling. */
__pthread_mutex_lock (mutex);
if (cancelled)
__pthread_exit (PTHREAD_CANCELED);
return err;
}
