On 8/8/2014 12:16 PM, Chris Angelico wrote:
On Sat, Aug 9, 2014 at 2:05 AM, Neil D. Cerutti <ne...@norwich.edu> wrote:
Perhaps defer release, a la a common Go pattern:
with contextlib.ExitStack() as stack:
acquired = lock.acquire(blocking=False)
if acquired:
stack.callback(lock.release)
do_stuff
There's a race condition in that - an unexpected exception could
happen between those two. Are you able to set the callback to be a
"release if acquired" atomic operation?
Doesn't any natural looking use of blocking=False suffer from the same
race condition? What's the correct way to use it?
Here's another attempt at context managing:
@contextlib.contextmanager
def release_if_acquired(lock, blocking=True, timeout=-1):
acquired = lock.acquire(blocking, timeout)
if acquired:
yield acquired
lock.release()
else:
yield acquired
with release_if_acquired(lock, blocking=False) as acquired:
if acquired:
do_stuff
--
Neil Cerutti
--
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