metrics

type Collector interface {
	// RecordCacheOperation records a cache operation (get, set, delete)
	// Parameters:
	//   - operation: "get", "set", or "delete"
	//   - backend: cache backend name (e.g., "memory", "redis", "leveldb")
	//   - result: operation result (e.g., "hit", "miss", "success", "error")
	//   - duration: operation duration
	RecordCacheOperation(operation, backend, result string, duration time.Duration)

	// RecordCacheSize records the current size of the cache in bytes
	// Parameters:
	//   - backend: cache backend name
	//   - sizeBytes: current cache size in bytes
	RecordCacheSize(backend string, sizeBytes int64)

	// RecordCacheEntries records the current number of entries in cache
	// Parameters:
	//   - backend: cache backend name
	//   - count: number of entries
	RecordCacheEntries(backend string, count int64)

	// RecordHTTPRequest records an HTTP request through the cache transport
	// Parameters:
	//   - method: HTTP method (GET, HEAD, etc.)
	//   - cacheStatus: "hit", "miss", "revalidated", or "bypass"
	//   - statusCode: HTTP status code
	//   - duration: request duration
	RecordHTTPRequest(method, cacheStatus string, statusCode int, duration time.Duration)

	// RecordHTTPResponseSize records the size of an HTTP response
	// Parameters:
	//   - cacheStatus: "hit" or "miss"
	//   - sizeBytes: response size in bytes
	RecordHTTPResponseSize(cacheStatus string, sizeBytes int64)

	// RecordStaleResponse records when a stale response is served on error
	// Parameters:
	//   - errorType: type of error (e.g., "network", "server_error", "timeout")
	RecordStaleResponse(errorType string)
}

type NoOpCollector struct{}