from __future__ import absolute_import, division import time import os import sys import errno from . import (LockBase, LockFailed, NotLocked, NotMyLock, LockTimeout, AlreadyLocked) class MkdirLockFile(LockBase): """Lock file by creating a directory.""" def __init__(self, path, threaded=True, timeout=None): """ >>> lock = MkdirLockFile('somefile') >>> lock = MkdirLockFile('somefile', threaded=False) """ LockBase.__init__(self, path, threaded, timeout) # Lock file itself is a directory. Place the unique file name into # it. self.unique_name = os.path.join(self.lock_file, "%s.%s%s" % (self.hostname, self.tname, self.pid)) def acquire(self, timeout=None): timeout = timeout if timeout is not None else self.timeout end_time = time.time() if timeout is not None and timeout > 0: end_time += timeout if timeout is None: wait = 0.1 else: wait = max(0, timeout / 10) while True: try: os.mkdir(self.lock_file) except OSError: err = sys.exc_info()[1] if err.errno == errno.EEXIST: # Already locked. if os.path.exists(self.unique_name): # Already locked by me. return if timeout is not None and time.time() > end_time: if timeout > 0: raise LockTimeout("Timeout waiting to acquire" " lock for %s" % self.path) else: # Someone else has the lock. raise AlreadyLocked("%s is already locked" % self.path) time.sleep(wait) else: # Couldn't create the lock for some other reason raise LockFailed("failed to create %s" % self.lock_file) else: open(self.unique_name, "wb").close() return def release(self): if not self.is_locked(): raise NotLocked("%s is not locked" % self.path) elif not os.path.exists(self.unique_name): raise NotMyLock("%s is locked, but not by me" % self.path) os.unlink(self.unique_name) os.rmdir(self.lock_file) def is_locked(self): return os.path.exists(self.lock_file) def i_am_locking(self): return (self.is_locked() and os.path.exists(self.unique_name)) def break_lock(self): if os.path.exists(self.lock_file): for name in os.listdir(self.lock_file): os.unlink(os.path.join(self.lock_file, name)) os.rmdir(self.lock_file)