| """ |
| Interprocess mutex based on file locks |
| """ |
| |
| import fcntl |
| import os |
| |
| class Lock: |
| |
| def __init__(self, filename): |
| self.filename = filename |
| # This will create it if it does not exist already |
| unbuffered = 0 |
| self.handle = open(filename, 'a+', unbuffered) |
| |
| def acquire(self): |
| fcntl.flock(self.handle, fcntl.LOCK_EX) |
| |
| # will throw IOError if unavailable |
| def try_acquire(self): |
| fcntl.flock(self.handle, fcntl.LOCK_NB | fcntl.LOCK_EX) |
| |
| def release(self): |
| fcntl.flock(self.handle, fcntl.LOCK_UN) |
| |
| def __del__(self): |
| self.handle.close() |
