IncrementCacheHits increments the cache hits counter.

IncrementCacheMisses increments the cache misses counter.

IncrementTotalRequests increments the total requests counter.

ObserveBackendResponseTime records the response time from the backend.

ObserveCacheHitResponseTime records the response time for cache hits.

ObserveCacheMissResponseTime records the response time for cache misses.

ObserveTotalResponseTime records the overall response time.

SetCacheItemCount sets the current number of items in the cache.

StartMetricsServer starts the Prometheus metrics server on the specified port.