diff options
Diffstat (limited to 'redis/lock.py')
| -rw-r--r-- | redis/lock.py | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/redis/lock.py b/redis/lock.py index 5524d7a..2bb7794 100644 --- a/redis/lock.py +++ b/redis/lock.py @@ -16,6 +16,7 @@ class Lock(object): lua_release = None lua_extend = None + lua_reacquire = None # KEYS[1] - lock name # ARGS[1] - token @@ -49,6 +50,19 @@ class Lock(object): return 1 """ + # KEYS[1] - lock name + # ARGS[1] - token + # ARGS[2] - milliseconds + # return 1 if the locks time was reacquired, otherwise 0 + LUA_REACQUIRE_SCRIPT = """ + local token = redis.call('get', KEYS[1]) + if not token or token ~= ARGV[1] then + return 0 + end + redis.call('pexpire', KEYS[1], ARGV[2]) + return 1 + """ + def __init__(self, redis, name, timeout=None, sleep=0.1, blocking=True, blocking_timeout=None, thread_local=True): """ @@ -121,6 +135,9 @@ class Lock(object): cls.lua_release = client.register_script(cls.LUA_RELEASE_SCRIPT) if cls.lua_extend is None: cls.lua_extend = client.register_script(cls.LUA_EXTEND_SCRIPT) + if cls.lua_reacquire is None: + cls.lua_reacquire = \ + client.register_script(cls.LUA_REACQUIRE_SCRIPT) def __enter__(self): # force blocking, as otherwise the user would have to check whether @@ -214,3 +231,22 @@ class Lock(object): raise LockNotOwnedError("Cannot extend a lock that's" " no longer owned") return True + + def reacquire(self): + """ + Resets a TTL of an already acquired lock back to a timeout value. + """ + if self.local.token is None: + raise LockError("Cannot reacquire an unlocked lock") + if self.timeout is None: + raise LockError("Cannot reacquire a lock with no timeout") + return self.do_reacquire() + + def do_reacquire(self): + timeout = int(self.timeout * 1000) + if not bool(self.lua_reacquire(keys=[self.name], + args=[self.local.token, timeout], + client=self.redis)): + raise LockNotOwnedError("Cannot reacquire a lock that's" + " no longer owned") + return True |