Documentation bug in usage example

[mrmachine]

This example

python-redis-lock/README.rst

Lines 103 to 114 in 1497012

	import socket
	host_id = "owned-by-%s" % socket.gethostname()
	lock = redis_lock.Lock(conn, "name-of-the-lock", id=host_id)
	if lock.acquire(blocking=False):
	assert lock.locked() is True
	print("Got the lock.")
	lock.release()
	else:
	if lock.get_owner_id() == host_id:
	print("I already acquired this in another process.")
	else:
	print("The lock is held on another machine.")

has an unreachable code path and implies an impossible use case.

The example implies that a lock with an explicit ID can return False from .acquire(blocking=False) AND have the lock owned by self per lock.get_owner_id() == host_id check, which is actually just the same check as _held property, which will instead cause .acquire(blocking=False) to raise an exception.

Ideally I would like to be able to give locks in multiple processes the same ID and be able to call .acquire(blocking=False) and have it return False instead of raising AlreadyAcquired. I thought that was possible from reading the examples.

Then when I got AlreadyAcquired I had to change my code to try .acquire(): except AlreadyAcquired instead of if .acquire(), which is fine, except that the example further confused me by implying I might need to support both False or AlreadyAcquired in the event that I am unable to acquire the lock.