def acquire(self, blocking=1):
tid = get_ident()
gid = id(getcurrent())
tid_gid = (tid, gid)
if tid_gid == self._owner: # We trust the GIL here so we can do this comparison w/o locking.
self._count = self._count + 1
return True
greenlet_lock = self._get_greenlet_lock()
self._wait_queue.append(gid)
# this is a safety in case an exception is raised somewhere and we must make sure we're not in the queue
# otherwise it'll get stuck forever.
remove_from_queue_on_return = True
try:
while True:
if not greenlet_lock.acquire(blocking):
return False # non-blocking and failed to acquire lock
if self._wait_queue[0] == gid:
# Hurray, we can have the lock.
self._owner = tid_gid
self._count = 1
remove_from_queue_on_return = False # don't remove us from the queue
return True
else:
# we already hold the greenlet lock so obviously the owner is not in our thread.
greenlet_lock.release()
if blocking:
sleep(0.0005) # 500 us -> initial delay of 1 ms
else:
return False
finally:
if remove_from_queue_on_return:
self._wait_queue.remove(gid)
def release(self):
tid_gid = (get_ident(), id(getcurrent()))
if tid_gid != self._owner:
raise RuntimeError("cannot release un-acquired lock")
self._count = self._count - 1
if not self._count:
self._owner = None
gid = self._wait_queue.pop(0)
assert gid == tid_gid[1]
self._thread_local.greenlet_lock.release()
def _is_owned(self):
return self._owner == (get_ident(), id(getcurrent()))
