Enable retries in redis driver

this is followup to Iaab5ce609c0dcf7085f5dd43efbd37eb4b88f17b

actually retry for specified number of retries instead of raising
error on first ConnectionError

Change-Id: Ibca3f568b65dfea252da4b67f6d5105ba7f1ecb1
(cherry picked from commit 47c4d56e44)
(cherry picked from commit 11526e594c)
(cherry picked from commit c1ae1649d2)

releasenotes/notes/redis-connect-retries-c9adfc81eb06a4ab.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Redis driver retries actions for up to 15 times when met with error
+    connecting to Redis.

tooz/drivers/redis.py

@@ -40,6 +40,7 @@ from tooz import utils
 LOG = logging.getLogger(__name__)
 
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
 @contextlib.contextmanager
 def _translate_failures():
     """Translates common redis exceptions into tooz exceptions."""
@@ -53,6 +54,48 @@ def _translate_failures():
         utils.raise_with_cause(tooz.ToozError,
                                encodeutils.exception_to_unicode(e),
                                cause=e)
+=======
+def _handle_failures(n_tries=15):
+
+    """Translates common redis exceptions into tooz exceptions.
+
+    This also enables retrying on certain exceptions.
+
+    :param func: the function to act on
+    :param n_tries: the number of retries
+    """
+    def inner(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            ntries = n_tries
+            while ntries:
+                try:
+                    return func(*args, **kwargs)
+                except exceptions.ConnectionError as e:
+                    # retry ntries times and then raise a connection error
+                    ntries -= 1
+                    if not ntries:
+                        LOG.debug(
+                            "Redis connection error, "
+                            "retry limit has been reached, aborting - %s", e
+                        )
+                        utils.raise_with_cause(
+                            coordination.ToozConnectionError,
+                            encodeutils.exception_to_unicode(e),
+                            cause=e)
+                    LOG.debug("Redis connection error, will retry - %s", e)
+
+                except (exceptions.TimeoutError) as e:
+                    utils.raise_with_cause(coordination.ToozConnectionError,
+                                           encodeutils.exception_to_unicode(e),
+                                           cause=e)
+                except exceptions.RedisError as e:
+                    utils.raise_with_cause(tooz.ToozError,
+                                           encodeutils.exception_to_unicode(e),
+                                           cause=e)
+        return wrapper
+    return inner
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
 
 
 class RedisLock(locking.Lock):
@@ -68,6 +111,10 @@ class RedisLock(locking.Lock):
         self._coord = coord
         self._client = client
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
+=======
+    @_handle_failures()
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
     def is_still_owner(self):
         with _translate_failures():
             lock_tok = self._lock.local.token
@@ -76,10 +123,18 @@ class RedisLock(locking.Lock):
             owner_tok = self._client.get(self.name)
             return owner_tok == lock_tok
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
+=======
+    @_handle_failures()
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
     def break_(self):
         with _translate_failures():
             return bool(self._client.delete(self.name))
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
+=======
+    @_handle_failures()
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
     def acquire(self, blocking=True, shared=False):
         if shared:
             raise tooz.NotImplemented
@@ -92,6 +147,10 @@ class RedisLock(locking.Lock):
                     self._coord._acquired_locks.add(self)
             return acquired
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
+=======
+    @_handle_failures()
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
     def release(self):
         with self._exclusive_access:
             with _translate_failures():
@@ -104,6 +163,10 @@ class RedisLock(locking.Lock):
                     self._coord._acquired_locks.discard(self)
                 return True
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
+=======
+    @_handle_failures()
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
     def heartbeat(self):
         with self._exclusive_access:
             if self.acquired:
@@ -438,6 +501,10 @@ return 1
             return master_client
         return redis.StrictRedis(**kwargs)
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
+=======
+    @_handle_failures()
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
     def _start(self):
         super(RedisDriver, self)._start()
         try:
@@ -511,6 +578,10 @@ return 1
     def _decode_group_id(self, group_id):
         return utils.to_binary(group_id, encoding=self._encoding)
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
+=======
+    @_handle_failures()
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
     def heartbeat(self):
         with _translate_failures():
             beat_id = self._encode_beat_id(self._member_id)
@@ -525,6 +596,10 @@ return 1
                             exc_info=True)
         return min(self.lock_timeout, self.membership_timeout)
 
+<<<<<<< HEAD   (667e2e Fix broken CI and PyMySQL support)
+=======
+    @_handle_failures()
+>>>>>>> CHANGE (c1ae16 Enable retries in redis driver)
     def _stop(self):
         while self._acquired_locks:
             lock = self._acquired_locks.pop()