feat: adding support for session caching for redis and dynamodb session stores for better performance

[tharindud]

Signed-off-by: Tharindu Dissanayake [email protected]

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Pull request overview

This PR introduces an optional in-memory LRU caching layer for Redis and DynamoDB session stores to improve performance by reducing backend storage lookups. The cache is configurable via a cache parameter in the session configuration, which specifies the maximum number of sessions to keep in memory.

Key changes:

• Implemented SessionCache class using OrderedDict with LRU eviction policy
• Modified RedisSessionStore and DynamoDBSessionStore to accept and use an optional SessionCache
• Added cache configuration parameter to session store config with default value of 0 (disabled)

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

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File	Description
ak-py/src/agentkernel/core/session/base.py	Added SessionCache class implementing LRU cache using OrderedDict
ak-py/src/agentkernel/core/session/redis.py	Integrated SessionCache into RedisSessionStore for load/store/clear operations
ak-py/src/agentkernel/core/session/dynamodb.py	Integrated SessionCache into DynamoDBSessionStore for load/store/clear operations
ak-py/src/agentkernel/core/config.py	Added optional cache configuration parameter to session store config
ak-py/src/agentkernel/core/builder.py	Modified SessionStoreBuilder to create SessionCache instance based on config and inject into stores
ak-py/tests/test_session.py	Added unit tests for SessionCache LRU eviction behavior
ak-py/tests/test_runtime.py	Updated test to include cache configuration parameter
examples/memory/redis/config.yaml	Added cache configuration example with value of 256
examples/memory/dynamodb/config.yaml	Added cache configuration example with value of 256

Comments suppressed due to low confidence (1)

ak-py/src/agentkernel/core/session/dynamodb.py:217

• After loading a session from DynamoDB storage (lines 212-217), the session is not added to the cache. This means subsequent loads for the same session will always hit DynamoDB instead of using the cached value, defeating the performance optimization purpose of this PR.

The loaded session should be cached before returning it to ensure cache consistency and improve performance.

        keys = self._driver.query_keys(session_id)
        if not keys:
            if strict:
                raise KeyError(f"Session {session_id} not found")
            self._log.warning("Session %s not found, creating new session", session_id)
            return self.new(session_id)

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Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 5 comments.

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Pull request overview

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