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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)