repair backwards incompat redis lock changes

Fixed regression caused by backwards-incompatible API changes in Redis that
caused the "distributed lock" feature to not function.

This commit also updates black which was not passing
due to the older version having dependency issues

Fixes: #220
Change-Id: Ibba3307dbfd9dfeacc08af79800b681ce160dea9

5 files changed, 37 insertions, 13 deletions

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 04d64a4..6d7ebae 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -2,25 +2,25 @@
 # See https://pre-commit.com/hooks.html for more hooks
 repos:
 -   repo: https://github.com/python/black
-    rev: 21.5b1
+    rev: 22.3.0
     hooks:
     -   id: black
 
 -   repo: https://github.com/sqlalchemyorg/zimports
-    rev: v0.4.1
+    rev: v0.6.0
     hooks:
     -   id: zimports
         args:
             - --keep-unused-type-checking
 
 -   repo: https://github.com/pycqa/flake8
-    rev: 3.9.2
+    rev: 4.0.1
     hooks:
     -   id: flake8
         additional_dependencies:
           - flake8-import-order
           - flake8-builtins
-          - flake8-docstrings>=1.3.1
+          - flake8-docstrings>=1.6.0
           - flake8-rst-docstrings
           - pydocstyle
           - pygments
diff --git a/docs/build/unreleased/220.rst b/docs/build/unreleased/220.rst
new file mode 100644
index 0000000..0d46c6b
--- /dev/null
+++ b/docs/build/unreleased/220.rst
@@ -0,0 +1,6 @@
+.. change::
+    :tags: bug, redis
+    :tickets: 220
+
+    Fixed regression caused by backwards-incompatible API changes in Redis that
+    caused the "distributed lock" feature to not function.
diff --git a/dogpile/cache/backends/memcached.py b/dogpile/cache/backends/memcached.py
index 8163d70..7c247bc 100644
--- a/dogpile/cache/backends/memcached.py
+++ b/dogpile/cache/backends/memcached.py
@@ -58,7 +58,7 @@ class MemcachedLock(object):
             elif not wait:
                 return False
             else:
-                sleep_time = (((i + 1) * random.random()) + 2 ** i) / 2.5
+                sleep_time = (((i + 1) * random.random()) + 2**i) / 2.5
                 time.sleep(sleep_time)
             if i < 15:
                 i += 1
diff --git a/dogpile/cache/backends/redis.py b/dogpile/cache/backends/redis.py
index 5bff3ea..cf646fe 100644
--- a/dogpile/cache/backends/redis.py
+++ b/dogpile/cache/backends/redis.py
@@ -150,11 +150,13 @@ class RedisBackend(BytesBackend):
 
     def get_mutex(self, key):
         if self.distributed_lock:
-            return self.writer_client.lock(
-                "_lock{0}".format(key),
-                timeout=self.lock_timeout,
-                sleep=self.lock_sleep,
-                thread_local=self.thread_local_lock,
+            return _RedisLockWrapper(
+                self.writer_client.lock(
+                    "_lock{0}".format(key),
+                    timeout=self.lock_timeout,
+                    sleep=self.lock_sleep,
+                    thread_local=self.thread_local_lock,
+                )
             )
         else:
             return None
@@ -193,6 +195,22 @@ class RedisBackend(BytesBackend):
         self.writer_client.delete(*keys)
 
 
+class _RedisLockWrapper:
+    __slots__ = ("mutex", "__weakref__")
+
+    def __init__(self, mutex: typing.Any):
+        self.mutex = mutex
+
+    def acquire(self, wait: bool = True) -> typing.Any:
+        return self.mutex.acquire(blocking=wait)
+
+    def release(self) -> typing.Any:
+        return self.mutex.release()
+
+    def locked(self) -> bool:
+        return self.mutex.locked()  # type: ignore
+
+
 class RedisSentinelBackend(RedisBackend):
     """A `Redis <http://redis.io/>`_ backend, using the
     `redis-py <http://pypi.python.org/pypi/redis/>`_ backend.
diff --git a/tox.ini b/tox.ini
index 31cff77..8b241dc 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,9 +39,9 @@ deps=
     {memcached}: python-binary-memcached>=0.29.0
     {memcached}: pifpaf>=2.5.0
     {memcached}: pymemcache>=3.5.0
-    {redis}: redis!=4.3.2,!=4.3.3
+    {redis}: redis
     {redis}: pifpaf
-    {redis_sentinel}: redis!=4.3.2,!=4.3.3
+    {redis_sentinel}: redis
     {redis_sentinel}: pifpaf
     {cov}: pytest-cov
 
@@ -83,7 +83,7 @@ deps=
       flake8-rst-docstrings
       # used by flake8-rst-docstrings
       pygments
-      black==21.5b1
+      black==22.3.0
 commands =
     flake8 ./dogpile/ ./tests/ setup.py  {posargs}
     black --check .