Streamline client side caching API typing #3216

gerzse · 2024-04-25T12:25:04Z

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Description of change

Streamline the typing of the client side caching API. Some of the methods are defining commands of type str, while in reality tuples are being sent for those parameters.

Add client side cache tests for Sentinels. In order to make this work, fix the sentinel configuration in the docker-compose stack.

Add a test for client side caching with a truly custom cache, not just injecting our internal cache structure as custom.

Add a test for client side caching where two different types of commands use the same key, to make sure they invalidate each others cached data.

codecov · 2024-04-25T12:28:56Z

Codecov Report

Attention: Patch coverage is 98.57143% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 91.94%. Comparing base (2f88840) to head (523dc7c).
Report is 20 commits behind head on master.

Files	Patch %	Lines
tests/test_cache.py	97.87%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3216      +/-   ##
==========================================
+ Coverage   91.84%   91.94%   +0.09%     
==========================================
  Files         128      128              
  Lines       33232    33517     +285     
==========================================
+ Hits        30523    30816     +293     
+ Misses       2709     2701       -8

☔ View full report in Codecov by Sentry.
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Streamline the typing of the client side caching API. Some of the methods are defining commands of type `str`, while in reality tuples are being sent for those parameters. Add client side cache tests for Sentinels. In order to make this work, fix the sentinel configuration in the docker-compose stack. Add a test for client side caching with a truly custom cache, not just injecting our internal cache structure as custom. Add a test for client side caching where two different types of commands use the same key, to make sure they invalidate each others cached data.

tests/test_asyncio/test_cache.py

dvora-h · 2024-04-30T09:35:34Z

redis/asyncio/connection.py

@@ -696,7 +696,7 @@ def _cache_invalidation_process(
        and the second string is the list of keys to invalidate.
        (if the list of keys is None, then all keys are invalidated)
        """
-        if data[1] is not None:
+        if data[1] is None:


Great catch! thanks

Surfaced due to the new tests, basically luck.

dvora-h · 2024-04-30T09:37:39Z

tests/test_asyncio/test_cache.py

 @pytest.mark.skipif(HIREDIS_AVAILABLE, reason="PythonParser only")
 class TestLocalCache:
-    @pytest.mark.onlynoncluster


Why? I think it will fail on cluster

I moved the decorator to class level.

Moved back.

dvora-h · 2024-04-30T09:39:21Z

tests/test_asyncio/test_cache.py

@@ -36,7 +41,7 @@ async def test_get_from_cache(self, r, r2):
        assert await r.get("foo") == b"barbar"

    @pytest.mark.parametrize("r", [{"cache": _LocalCache(max_size=3)}], indirect=True)
-    async def test_cache_max_size(self, r):
+    async def test_cache_lru_eviction(self, r):


Why? this test checks that if I set the max_size to 3 it will not save more than 3 in the cache

There was a discussion about eviction policies. Max size is always bound to an eviction policy. It felt cleaner to express this as "test that the default eviction policy is LRU".

Could you refer me to this discussion?

The discussion was mostly online, in the weekly call. Another argument: all tests for eviction strategies implicitly test the max size of the cache.

tests/test_asyncio/test_cache.py

dev_requirements.txt

dvora-h · 2024-04-30T10:16:25Z

redis/_cache.py

-    def set(self, command: str, response: ResponseT, keys_in_command: List[KeyT]):
+    def set(
+        self,
+        command: Union[str, Iterable[str]],


Why it need to be also Iterable[str]?

Because in all unit tests tuples are being sent for this parameter.

Not in unit tests, that is for the get. In Connection we have this signature for example:

def _add_to_local_cache( self, command: Tuple[str], response: ResponseT, keys: List[KeysT] ):

So maybe we need only Iterable[str]? I'm not sure...

This is a broader discussion, I think we can leave it with both for the beta release. In general I think we should not expose to the outside world the way we represent commands in the cache. We should only expose the concept of keys externally, and do the mapping to commands and back only internally, and then we have full freedom of representation.

I used Sequence instead of Iterable and Tuple. I think it is the most expressive one.

tests/test_cache.py

dvora-h · 2024-04-30T10:25:20Z

tests/test_cache.py

+        [{"cache": _LocalCache(max_size=3)}],
+        indirect=True,
+    )
+    def test_cache_lru_eviction(self, r):


same as in the async test (naming)

Yes, same reason as above.

dvora-h · 2024-04-30T10:38:08Z

redis/asyncio/connection.py

@@ -730,6 +730,27 @@ def _add_to_local_cache(
        ):
            self.client_cache.set(command, response, keys)

+    def flush_cache(self):
+        try:
+            if self.client_cache:


Why do you need the if inside the try block?

The try is meant to compensate for the if? You mean we could leave the if without the try? I would find that cleaner.

The if-statement will prevent the call to flush/delete_command/invalidate_key that would cause the AttributeError if client_cache is falsy. The try-catch-block will also catch an AttributeError if client_cache is truthy but doesn't provide the method.
I'm missing to much context to say which is more desirable. But if it can be assumed, that a thruthy client_cache always also provides the methods, then the if-statement and try-catch are redundant and it becomes a question of style. You can read more on that here https://realpython.com/python-lbyl-vs-eafp/
Best regards, a random passerby XD

Thanks @CBerndt-Work for your nice explanation. The article is very well written. I realized that I am by now too conditioned towards LBYL, from other languages. Especially here, using AttributeError, which signals issues with the code structure, not with data. So I went for the ifs.

gerzse requested a review from uglide April 25, 2024 12:25

gerzse force-pushed the client-side-caching-cleanup branch 2 times, most recently from 0436538 to a55cdb1 Compare April 25, 2024 13:16

gerzse force-pushed the client-side-caching-cleanup branch from a55cdb1 to 523dc7c Compare April 25, 2024 14:42

gerzse requested a review from vladvildanov April 29, 2024 11:19

vladvildanov reviewed Apr 29, 2024

View reviewed changes

tests/test_asyncio/test_cache.py Show resolved Hide resolved

Gabriel Erzse added 6 commits April 29, 2024 17:54

Fixes after running tests against RE

93709ea

More test cases

a157347

Fix async tests

106d794

Tests for raw commands

48b43f4

Change terminology for allow/deny lists

0d60ff4

Add test for single connection

4691a9c

vladvildanov approved these changes Apr 30, 2024

View reviewed changes

Make sure flushing the cache works everywhere

eab6973

gerzse requested a review from dvora-h April 30, 2024 10:29

dvora-h reviewed Apr 30, 2024

View reviewed changes

Gabriel Erzse added 4 commits April 30, 2024 14:03

Reenable some tests for cluster too

fcebcaa

Align cache typings at abstract level

3a9d360

Use Sequence instead of Iterable for types

27c5544

Remove some exceptions in favor of ifs

92608b5

dvora-h approved these changes May 5, 2024

View reviewed changes

dvora-h added bug Bug maintenance Maintenance (CI, Releases, etc) labels May 8, 2024

dvora-h merged commit 3bd311c into redis:master May 8, 2024
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Streamline client side caching API typing #3216

Streamline client side caching API typing #3216

gerzse commented Apr 25, 2024 •

edited

codecov bot commented Apr 25, 2024 •

edited

dvora-h Apr 30, 2024

gerzse Apr 30, 2024

dvora-h Apr 30, 2024

gerzse Apr 30, 2024

gerzse Apr 30, 2024

dvora-h Apr 30, 2024

gerzse Apr 30, 2024

dvora-h Apr 30, 2024

gerzse Apr 30, 2024

dvora-h Apr 30, 2024

gerzse Apr 30, 2024

gerzse Apr 30, 2024

dvora-h Apr 30, 2024

gerzse Apr 30, 2024

gerzse Apr 30, 2024

dvora-h Apr 30, 2024

gerzse Apr 30, 2024

dvora-h Apr 30, 2024

gerzse Apr 30, 2024

CBerndt-Work Apr 30, 2024

gerzse Apr 30, 2024

Streamline client side caching API typing #3216

Streamline client side caching API typing #3216

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gerzse commented Apr 25, 2024 • edited

Pull Request check-list

Description of change

codecov bot commented Apr 25, 2024 • edited

Codecov Report

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gerzse commented Apr 25, 2024 •

edited

codecov bot commented Apr 25, 2024 •

edited