Extend lock error for not owned special case

Using the locking routines, it is useful to be able to
distingush a generic lock error from a one that is related
to the lock not being owned anymore (without doing string
checks); this allows say a lock extension thread to attempt
to re-acquire the lock in this case (vs just dying).

1 files changed, 5 insertions, 3 deletions

diff --git a/redis/lock.py b/redis/lock.py
index c6fd01d..38ab0bf 100644
--- a/redis/lock.py
+++ b/redis/lock.py
@@ -1,7 +1,7 @@
 import threading
 import time as mod_time
 import uuid
-from redis.exceptions import LockError
+from redis.exceptions import LockError, LockErrorNotOwned
 from redis.utils import dummy
 
 
@@ -190,7 +190,8 @@ class Lock(object):
         if not bool(self.lua_release(keys=[self.name],
                                      args=[expected_token],
                                      client=self.redis)):
-            raise LockError("Cannot release a lock that's no longer owned")
+            raise LockErrorNotOwned("Cannot release a lock"
+                                    " that's no longer owned")
 
     def extend(self, additional_time):
         """
@@ -210,5 +211,6 @@ class Lock(object):
         if not bool(self.lua_extend(keys=[self.name],
                                     args=[self.local.token, additional_time],
                                     client=self.redis)):
-            raise LockError("Cannot extend a lock that's no longer owned")
+            raise LockErrorNotOwned("Cannot extend a lock that's"
+                                    " no longer owned")
         return True