Django cache-based lock, originally for distributed Celery tasks

cache_lock.py

import gevent
from django.core.cache import cache


class CacheLock(object):
    """A lock backed by redis"""

    def __init__(self, lock_id, expiry=60 * 5):
        """
        :param lock_id: unique key for lock (unique through Django cache)
        :param expiry: expiry of lock, in seconds
        """
        self.lock_id = lock_id
        self.expiry = expiry

    def __enter__(self):
        self.acquire()

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.release()

    def acquire(self, block=True):
        while not self._acquire():
            if block:
                gevent.sleep(0.1)
            else:
                return False
        return True

    def release(self):
        cache.delete(self.lock_id)

    def _acquire(self):
        return cache.add(self.lock_id, 'true', self.expiry)