import time

class FileLock:

def __init__(self, path, timeout=10):

self.path, self.timeout = path, timeout

def __enter__(self):

deadline = time.monotonic() + self.timeout

while not self._try_acquire():

if time.monotonic() > deadline: raise TimeoutError(self.path)

time.sleep(0.1)

return self

def __exit__(self, exc_type, exc, tb):

self._release() # runs even if the with-body raised

return False # don't suppress exceptions

A class context manager implements __enter__ (setup, returns the resource) and __exit__ (teardown, always runs). __exit__ receives any exception info; returning False lets the exception propagate (returning True would swallow it — rarely what you want). This pattern guarantees the lock is released even if the protected block raises, and the timeout prevents waiting forever on a stuck lock.

Always release in __exit__: putting release there (not after the with-body) is what makes it exception-safe. Return False so you don't accidentally hide errors that occurred inside the block.