diff options
Diffstat (limited to 'lib/thandy/lockfile/mkdirlockfile.py')
-rw-r--r-- | lib/thandy/lockfile/mkdirlockfile.py | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/lib/thandy/lockfile/mkdirlockfile.py b/lib/thandy/lockfile/mkdirlockfile.py new file mode 100644 index 0000000..fb78902 --- /dev/null +++ b/lib/thandy/lockfile/mkdirlockfile.py @@ -0,0 +1,79 @@ +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): + """ + >>> lock = MkdirLockFile('somefile') + >>> lock = MkdirLockFile('somefile', threaded=False) + """ + LockBase.__init__(self, path, threaded) + # 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): + 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 + else: + # Someone else has the lock. + raise AlreadyLocked + 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 + elif not os.path.exists(self.unique_name): + raise NotMyLock + 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) |