Added CSC metrics export

[vladvildanov]

Description of change

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[Copilot]

Pull request overview

This pull request adds Client-Side Caching (CSC) metrics export functionality to redis-py, enabling observability for cache operations including cache hits, misses, evictions, and network bytes saved.

Changes:

• Introduced CSC metric instruments (requests, evictions, network_saved, items gauge) and event-driven observability
• Added CacheProxy wrapper to intercept cache operations and emit observability events
• Moved cache eviction logic from DefaultCache to CacheProxy to enable event emission on evictions

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
redis/cache.py	Added CacheProxy wrapper class to intercept cache operations; moved eviction logic from DefaultCache.set() to CacheProxy.set(); updated CacheFactory to wrap caches in CacheProxy
redis/connection.py	Added db and _event_dispatcher attributes to CacheProxyConnection; dispatched OnCacheHitEvent, OnCacheMissEvent, and OnCacheEvictionEvent at appropriate points; wrapped cache_factory output in CacheProxy
redis/event.py	Added CSC event classes (OnCacheHitEvent, OnCacheMissEvent, OnCacheInitialisationEvent, OnCacheEvictionEvent) and corresponding listener classes; registered CSC listeners in EventDispatcher
redis/observability/attributes.py	Added CSCResult and CSCReason enums; added REDIS_CLIENT_CSC_RESULT and REDIS_CLIENT_CSC_REASON constants; added build_csc_attributes() method
redis/observability/metrics.py	Added CSC metric initialization (_init_csc_metrics); added CSC recording methods (record_csc_request, record_csc_eviction, record_csc_network_saved, init_csc_items)
redis/observability/recorder.py	Added public recorder functions for CSC metrics (record_csc_request, init_csc_items, record_csc_eviction, record_csc_network_saved)
tests/test_cache.py	Added TestUnitCacheProxy test class with comprehensive tests for CacheProxy functionality; removed test_set_evict_lru_cache_key_on_reaching_max_size
tests/test_connection.py	Added db and _event_dispatcher mock attributes to test fixtures; added tests for cache hit/miss event emission

Comments suppressed due to low confidence (1)

redis/connection.py:2567

• Inconsistent cache handling: when cache_factory is used (line 2563), the cache is wrapped in CacheProxy, but when a cache is provided directly via the cache parameter (line 2560), it's used as-is without wrapping. This means directly provided caches won't emit CSC observability events (OnCacheInitialisationEvent, OnCacheEvictionEvent). Either document this difference or ensure both paths result in wrapped caches for consistency.

            cache = self._connection_kwargs.get("cache")

            if cache is not None:
                if not isinstance(cache, CacheInterface):
                    raise ValueError("Cache must implement CacheInterface")

                self.cache = cache
            else:
                if self._cache_factory is not None:
                    self.cache = CacheProxy(self._cache_factory.get_cache())
                else:
                    self.cache = CacheFactory(
                        self._connection_kwargs.get("cache_config")
                    ).get_cache()

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[petyaslavova]

LGTM.