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class Lock():
"""Simple implementation of a mutex lock using the file systems. Works on
*nix systems."""
path = None
_has_lock = False
def __init__(self, path):
self.path = path
def obtain(self):
import os
import logging
logger = logging.getLogger()
try:
os.open(self.path, os.O_CREAT | os.O_EXCL | os.O_WRONLY)
self._has_lock = True
logger.info("Successfully obtained lock: %s" % self.path)
except OSError:
return False
else:
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")
try:
os.remove(self.path)
logger.info("Successfully released lock: %s" % self.path)
finally:
self._has_lock = False
def has_lock(self):
return self._has_lock
def clear(self):
import os
import logging
logger = logging.getLogger()
try:
os.remove(self.path)
except OSError:
pass
finally:
logger.info("Successfully cleared lock: %s" % self.path)
self._has_lock = False
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