Redis Cluster Support

[vinothprakashk]

Facing the below typecase issue while trying to type case redis cluster instance to the Redis [bytes] instance

Python: 3.11
Redis: ~5.2.1
Dogpile: 1.3.3

File "/.venv311/lib/python3.11/site-packages/dogpile/cache/backends/redis.py", line 568, in _create_client
self.writer_client = typing.cast(redis.Redis[bytes], redis_cluster)
~~~~~~~~~~~^^^^^^^
File "/.pyenv/versions/3.11.10/lib/python3.11/typing.py", line 379, in inner
return func(*args, **kwds)
^^^^^^^^^^^^^^^^^^^
File ".pyenv/versions/3.11.10/lib/python3.11/typing.py", line 1864, in class_getitem
_check_generic(cls, params, len(cls.parameters))
File ".pyenv/versions/3.11.10/lib/python3.11/typing.py", line 290, in _check_generic
raise TypeError(f"{cls} is not a generic class")
TypeError: <class 'redis.client.Redis'> is not a generic class

[vinothprakashk]

is there any specific redis version i have to use?

[zzzeek]

cc @maeln this is an issue in the redis cluster you contributed in #250 ; it looks like redis.Redis[bytes] is not valid since Redis is not a generic class. Have you actually used your backend or tested it?

[zzzeek]

@vinothprakashk we have no way to test Redis Cluster here, can you apply this patch and see if you can otherwise get the backend working, thanks

diff --git a/dogpile/cache/backends/redis.py b/dogpile/cache/backends/redis.py
index cde17b2..797f46c 100644
--- a/dogpile/cache/backends/redis.py
+++ b/dogpile/cache/backends/redis.py
@@ -565,5 +565,5 @@ class RedisClusterBackend(RedisBackend):
                 startup_nodes=self.startup_nodes,
                 **self.connection_kwargs,
             )
-        self.writer_client = typing.cast(redis.Redis[bytes], redis_cluster)
+        self.writer_client = typing.cast("redis.Redis[bytes]", redis_cluster)
         self.reader_client = self.writer_client

[sqla-tester]

Mike Bayer has proposed a fix for this issue in the main branch:

dont evaluate Redis as a generic at runtime https://gerrit.sqlalchemy.org/c/sqlalchemy/dogpile.cache/+/5657

[vinothprakashk]

typing.cast("redis.Redis[bytes]", redis_cluster)

@zzzeek the patch you provided is working as expected!

[zzzeek]

OK I can release this in a few minutes

[vinothprakashk]

@zzzeek Thank you very much for the lightning-fast response.

[vinothprakashk]

@zzzeek When I can expect this change in the package release?

[zzzeek]

it's released