c

#!/usr/bin/env python
# coding=utf-8

import redis
import time, datetime


def acquire_lock(conn, lockname, identifier, expire=10):
    if conn.setnx(lockname, identifier):
        conn.expire(lockname, expire)
        return identifier
    elif not conn.ttl(lockname):
        conn.expire(lockname, expire)
    return False

def release_lock(conn, lockname, identifier):
    pipe = conn.pipeline(True)
    while True:
        try:
            pipe.watch(lockname)
            if pipe.get(lockname) == identifier:
                pipe.multi()
                pipe.delete(lockname)
                pipe.execute()
                return True
            pipe.unwatch()
            break
        except redis.exceptions.WatchError:
            pass
    # we lost the lock
    return False

conn = redis.Redis(host='localhost', port=6379, db=0)

# 1 identifier
# 2 False
# 11 True
# 22 False
# 33 barx2
# 44 True

ret = acquire_lock(conn, "lockname", "identifier", 3)
print("1", ret)
ret = acquire_lock(conn, "lockname", "identifier", 3)
print("2", ret)
ret = release_lock(conn, "lockname", "identifier")
print("11", ret)
ret = release_lock(conn, "lockname", "identifier")
print("22", ret)
ret = acquire_lock(conn, "footest", "bartest", 10)
print("33", ret)