void
test_and ()
{
v = init;
atomic_fetch_and (&v, 0);
if (v != 0)
abort ();
v = init;
atomic_fetch_and_explicit (&v, init, memory_order_consume);
if (v != init)
abort ();
atomic_fetch_and (&v, 0);
if (v != 0)
abort ();
v = ~v;
atomic_fetch_and_explicit (&v, init, memory_order_release);
if (v != init)
abort ();
atomic_fetch_and (&v, 0);
if (v != 0)
abort ();
v = ~v;
atomic_fetch_and_explicit (&v, 0, memory_order_seq_cst);
if (v != 0)
abort ();
}
static int __pthread_rwlock_timedrdlock(pthread_rwlock_internal_t* rwlock,
const timespec* abs_timeout_or_null) {
if (atomic_load_explicit(&rwlock->writer_tid, memory_order_relaxed) == __get_thread()->tid) {
return EDEADLK;
}
while (true) {
int result = __pthread_rwlock_tryrdlock(rwlock);
if (result == 0 || result == EAGAIN) {
return result;
}
result = check_timespec(abs_timeout_or_null);
if (result != 0) {
return result;
}
int old_state = atomic_load_explicit(&rwlock->state, memory_order_relaxed);
if (__can_acquire_read_lock(old_state, rwlock->writer_nonrecursive_preferred)) {
continue;
}
rwlock->pending_lock.lock();
rwlock->pending_reader_count++;
// We rely on the fact that all atomic exchange operations on the same object (here it is
// rwlock->state) always appear to occur in a single total order. If the pending flag is added
// before unlocking, the unlocking thread will wakeup the waiter. Otherwise, we will see the
// state is unlocked and will not wait anymore.
old_state = atomic_fetch_or_explicit(&rwlock->state, STATE_HAVE_PENDING_READERS_FLAG,
memory_order_relaxed);
int old_serial = rwlock->pending_reader_wakeup_serial;
rwlock->pending_lock.unlock();
int futex_result = 0;
if (!__can_acquire_read_lock(old_state, rwlock->writer_nonrecursive_preferred)) {
futex_result = __futex_wait_ex(&rwlock->pending_reader_wakeup_serial, rwlock->pshared,
old_serial, true, abs_timeout_or_null);
}
rwlock->pending_lock.lock();
rwlock->pending_reader_count--;
if (rwlock->pending_reader_count == 0) {
atomic_fetch_and_explicit(&rwlock->state, ~STATE_HAVE_PENDING_READERS_FLAG,
memory_order_relaxed);
}
rwlock->pending_lock.unlock();
if (futex_result == -ETIMEDOUT) {
return ETIMEDOUT;
}
}
}
void
test_fetch_and ()
{
v = init;
if (atomic_fetch_and_explicit (&v, 0, memory_order_relaxed) != init)
abort ();
if (atomic_fetch_and_explicit (&v, init, memory_order_consume) != 0)
abort ();
if (atomic_fetch_and_explicit (&v, 0, memory_order_acquire) != 0)
abort ();
v = ~v;
if (atomic_fetch_and_explicit (&v, init, memory_order_release) != init)
abort ();
if (atomic_fetch_and_explicit (&v, 0, memory_order_acq_rel) != init)
abort ();
if (atomic_fetch_and_explicit (&v, 0, memory_order_seq_cst) != 0)
abort ();
if (atomic_fetch_and (&v, 0) != 0)
abort ();
}
static int __pthread_rwlock_timedwrlock(pthread_rwlock_internal_t* rwlock,
const timespec* abs_timeout_or_null) {
if (atomic_load_explicit(&rwlock->writer_tid, memory_order_relaxed) == __get_thread()->tid) {
return EDEADLK;
}
while (true) {
int result = __pthread_rwlock_trywrlock(rwlock);
if (result == 0) {
return result;
}
result = check_timespec(abs_timeout_or_null);
if (result != 0) {
return result;
}
int old_state = atomic_load_explicit(&rwlock->state, memory_order_relaxed);
if (__can_acquire_write_lock(old_state)) {
continue;
}
rwlock->pending_lock.lock();
rwlock->pending_writer_count++;
old_state = atomic_fetch_or_explicit(&rwlock->state, STATE_HAVE_PENDING_WRITERS_FLAG,
memory_order_relaxed);
int old_serial = rwlock->pending_writer_wakeup_serial;
rwlock->pending_lock.unlock();
int futex_result = 0;
if (!__can_acquire_write_lock(old_state)) {
futex_result = __futex_wait_ex(&rwlock->pending_writer_wakeup_serial, rwlock->pshared,
old_serial, true, abs_timeout_or_null);
}
rwlock->pending_lock.lock();
rwlock->pending_writer_count--;
if (rwlock->pending_writer_count == 0) {
atomic_fetch_and_explicit(&rwlock->state, ~STATE_HAVE_PENDING_WRITERS_FLAG,
memory_order_relaxed);
}
rwlock->pending_lock.unlock();
if (futex_result == -ETIMEDOUT) {
return ETIMEDOUT;
}
}
}
void vlc_cancel (vlc_thread_t thread_id)
{
atomic_int *addr;
atomic_store(&thread_id->killed, true);
vlc_mutex_lock(&thread_id->wait.lock);
addr = thread_id->wait.addr;
if (addr != NULL)
{
atomic_fetch_and_explicit(addr, -2, memory_order_relaxed);
vlc_addr_broadcast(addr);
}
vlc_mutex_unlock(&thread_id->wait.lock);
}
int pthread_rwlock_unlock(pthread_rwlock_t* rwlock_interface) {
pthread_rwlock_internal_t* rwlock = __get_internal_rwlock(rwlock_interface);
int old_state = atomic_load_explicit(&rwlock->state, memory_order_relaxed);
if (__state_owned_by_writer(old_state)) {
if (atomic_load_explicit(&rwlock->writer_tid, memory_order_relaxed) != __get_thread()->tid) {
return EPERM;
}
atomic_store_explicit(&rwlock->writer_tid, 0, memory_order_relaxed);
old_state = atomic_fetch_and_explicit(&rwlock->state, ~STATE_OWNED_BY_WRITER_FLAG,
memory_order_release);
if (!__state_have_pending_readers_or_writers(old_state)) {
return 0;
}
} else if (__state_owned_by_readers(old_state)) {
old_state = atomic_fetch_sub_explicit(&rwlock->state, STATE_READER_COUNT_CHANGE_STEP,
memory_order_release);
if (!__state_is_last_reader(old_state) || !__state_have_pending_readers_or_writers(old_state)) {
return 0;
}
} else {
return EPERM;
}
// Wake up pending readers or writers.
rwlock->pending_lock.lock();
if (rwlock->pending_writer_count != 0) {
rwlock->pending_writer_wakeup_serial++;
rwlock->pending_lock.unlock();
__futex_wake_ex(&rwlock->pending_writer_wakeup_serial, rwlock->pshared, 1);
} else if (rwlock->pending_reader_count != 0) {
rwlock->pending_reader_wakeup_serial++;
rwlock->pending_lock.unlock();
__futex_wake_ex(&rwlock->pending_reader_wakeup_serial, rwlock->pshared, INT_MAX);
} else {
// It happens when waiters are woken up by timeout.
rwlock->pending_lock.unlock();
}
return 0;
}
TEST(stdatomic, atomic_fetch_and) {
atomic_int i = ATOMIC_VAR_INIT(0x123);
ASSERT_EQ(0x123, atomic_fetch_and(&i, 0x00f));
ASSERT_EQ(0x003, atomic_fetch_and_explicit(&i, 0x2, memory_order_relaxed));
ASSERT_EQ(0x002, atomic_load(&i));
}
