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class Lock():
"""Simple implementation of a mutex lock using the file systems. Works on
*nix systems."""
path = None
lock = None
def __init__(self, path):
try:
from lockfile import LockFile
except ImportError:
from lockfile import FileLock
# Different naming in older versions of lockfile
LockFile = FileLock
self.path = path
self.lock = LockFile(path)
def obtain(self):
import os
import logging
from lockfile import AlreadyLocked
logger = logging.getLogger()
try:
self.lock.acquire(0)
logger.debug("Successfully obtained lock: %s" % self.path)
except AlreadyLocked:
return False
return True
def release(self):
import os
import logging
logger = logging.getLogger()
if not self.has_lock():
raise Exception("Unable to release lock that is owned by another process")
self.lock.release()
logger.debug("Successfully released lock: %s" % self.path)
def has_lock(self):
return self.lock.i_am_locking()
def clear(self):
import os
import logging
logger = logging.getLogger()
self.lock.break_lock()
logger.debug("Successfully cleared lock: %s" % self.path)
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