Added a local digest command to the client to execute the XXH3 locally… #3884

dmaier-redislabs · 2025-12-15T14:34:28Z

Added a local digest command to the client to execute the XXH3 locally rather than using a server roundtrip.

@petyaslavova I added this for now as a command next to the digest command. There are indeed some discussion points:

Should we expose this as a normal command digest_local?
Would it make sense to parameterize the digest command instead to have a boolean exec_local parameter?
Do we want to expose this that way or move it more to helper section

BTW: This adds xxhash~=3.6.0 as an additional dependency.

jit-ci · 2025-12-15T14:34:36Z

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… rather than asking the server for it

… as an optional dependency

…for cosmetical reasons

…n of decode_responces setting. Adding test that validates the digets_local return type as well as the returned value.

Copilot

Pull request overview

This pull request adds a new digest_local command to compute XXH3 hashes locally on the client side, eliminating the need for a server roundtrip. This is particularly useful for conditional operations like IFDEQ/IFDNE where the digest needs to be computed client-side before sending commands.

Changes:

Added digest_local method to compute XXH3 digests locally using the xxhash library
Added xxhash as an optional dependency with version constraint ~=3.6.0
Added comprehensive tests for both sync and async clients to verify local digest matches server digest

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
redis/commands/core.py	Implements the `digest_local` method with xxhash library import handling and encoding/decoding logic
pyproject.toml	Adds xxhash as an optional dependency under the [project.optional-dependencies] section
dev_requirements.txt	Pins xxhash==3.6.0 for development environment
tests/test_commands.py	Adds test to verify local digest matches server digest, and integrates digest_local into existing IFDEQ/IFDNE tests
tests/test_asyncio/test_commands.py	Adds async version of the local digest test

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Copilot · 2026-01-16T09:11:54Z

redis/commands/core.py

+        local_digest = xxhash.xxh3_64(value).hexdigest()
+
+        # To align with digest, we want to return bytes if decode_responses is False.
+        # The following should work because Python's mixin approach.


The comment "The following should work because Python's mixin approach" is unclear and grammatically incomplete. Consider revising to: "The following should work because of Python's mixin approach" or providing more context about what specifically about the mixin approach makes this work.

Suggested change

# The following should work because Python's mixin approach.

# The following works because of Python's mixin-based client class hierarchy.

pyproject.toml

Copilot · 2026-01-16T09:11:55Z

tests/test_asyncio/test_commands.py

+        if isinstance(res_server, bytes):
+            assert isinstance(res_local, bytes)


The test only verifies that res_local is bytes when res_server is bytes, but doesn't verify the opposite case when decode_responses=True. Consider adding an else clause to assert that both are strings when decode_responses=True, ensuring type consistency between server and local digest in both modes.

Copilot · 2026-01-16T09:11:55Z

tests/test_commands.py

+    @pytest.mark.parametrize(
+        "value", [b"", b"abc", b"The quick brown fox jumps over the lazy dog"]
+    )


The test only covers bytes values but the digest_local method accepts Union[bytes, str] according to its type annotation. Consider adding test cases with string values to ensure the method correctly handles both bytes and str inputs, especially considering encoding issues.

Copilot · 2026-01-16T09:11:55Z

tests/test_asyncio/test_commands.py

+    @pytest.mark.parametrize(
+        "value", [b"", b"abc", b"The quick brown fox jumps over the lazy dog"]
+    )


The test only covers bytes values but the digest_local method accepts Union[bytes, str] according to its type annotation. Consider adding test cases with string values to ensure the method correctly handles both bytes and str inputs, especially considering encoding issues.

Copilot · 2026-01-16T09:11:56Z

redis/commands/core.py

+
+# Try to import the xxhash library as an optional dependency
+try:
+    import xxhash
+
+    HAS_XXHASH = True
+except ImportError:
+    HAS_XXHASH = False
+


The optional import block should be placed after other standard library imports to follow PEP 8 import ordering conventions. The blank line on line 5 creates unnecessary separation in the standard library imports section. Consider moving the try-except block to after line 14 (after the warnings import) and removing the blank line at line 5.

redis/commands/core.py

Copilot · 2026-01-16T09:11:56Z

redis/commands/core.py

+    def digest_local(self, value: Union[bytes, str]) -> Union[bytes, str]:
+        """
+        Compute the hexadecimal digest of the value locally, without sending it to the server.
+
+        This is useful for conditional operations like IFDEQ/IFDNE where you need to
+        compute the digest client-side before sending a command.
+
+        Warning:
+        **Experimental** - This API may change or be removed without notice.
+
+        Arguments:
+          - value: Union[bytes, str] - the value to compute the digest of.
+
+        Returns:
+          - (str | bytes) the XXH3 digest of the value as a hex string (16 hex characters)
+
+        For more information, see https://redis.io/commands/digest
+        """
+        if not HAS_XXHASH:
+            raise NotImplementedError(
+                "XXHASH library not installed. Install with: "
+                "'pip install xxhash' or 'pip install redis[xxhash]' to use this feature."
+            )
+
+        local_digest = xxhash.xxh3_64(value).hexdigest()
+
+        # To align with digest, we want to return bytes if decode_responses is False.
+        # The following should work because Python's mixin approach.
+        if not self.get_encoder().decode_responses:
+            local_digest = local_digest.encode()
+
+        return local_digest


Missing test coverage for the case when the xxhash library is not installed. Consider adding a test that verifies the NotImplementedError is raised with an appropriate message when digest_local is called without the xxhash dependency available. This would ensure the error handling path works correctly.

Copilot · 2026-01-16T09:11:56Z

tests/test_commands.py

+        if isinstance(res_server, bytes):
+            assert isinstance(res_local, bytes)


The test only verifies that res_local is bytes when res_server is bytes, but doesn't verify the opposite case when decode_responses=True. Consider adding an else clause to assert that both are strings when decode_responses=True, ensuring type consistency between server and local digest in both modes.

tests/test_asyncio/test_commands.py

Co-authored-by: Copilot <[email protected]>

petyaslavova added the feature New feature label Jan 8, 2026

dmaier-redislabs and others added 8 commits January 12, 2026 15:05

Added a locl digest command to the client to execute the XXH3 locally…

c4e87a0

… rather than asking the server for it

Removed an unnecessary import

19fcdda

Added a native implementation of XXH3 and declared the xxhash library…

e5ebbfc

… as an optional dependency

Fixed an import

5ca6113

Passing the actual value to xxhash

cc2c8c9

Fixed an issue with the return type

d3bff7e

Another change to align the response type of digest_local and digest …

4c4a765

…for cosmetical reasons

Removing the slow pure-python digest implementation. Fixing extractio…

bffee09

…n of decode_responces setting. Adding test that validates the digets_local return type as well as the returned value.

petyaslavova force-pushed the dmaier-digest branch from 5c02c59 to bffee09 Compare January 12, 2026 16:18

Adding xxhash as test dependency

b3180a2

petyaslavova requested review from Copilot and vladvildanov January 16, 2026 09:06

Copilot started reviewing on behalf of petyaslavova January 16, 2026 09:07 View session

Copilot AI reviewed Jan 16, 2026

View reviewed changes

petyaslavova and others added 3 commits January 16, 2026 11:19

Update redis/commands/core.py

0c76b07

Co-authored-by: Copilot <[email protected]>

Update pyproject.toml

23ccc4c

Co-authored-by: Copilot <[email protected]>

Update tests/test_asyncio/test_commands.py

a31fb5d

Co-authored-by: Copilot <[email protected]>

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Added a local digest command to the client to execute the XXH3 locally… #3884

Added a local digest command to the client to execute the XXH3 locally… #3884

dmaier-redislabs commented Dec 15, 2025 •

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	# The following should work because Python's mixin approach.
	# The following works because of Python's mixin-based client class hierarchy.

		if isinstance(res_server, bytes):
		assert isinstance(res_local, bytes)

Added a local digest command to the client to execute the XXH3 locally… #3884

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Added a local digest command to the client to execute the XXH3 locally… #3884

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dmaier-redislabs commented Dec 15, 2025 •

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