CloudCacheTier is used for cloud storage cache implementations, like GCS or AWS S3.

MemoryCacheTier is used for in-memory cache implementations, like memcached and redis.

InstrumentedReader wraps a Reader and CacheTimer so that the embedded timer is stopped and metrics are recorded on the last read.

CacheTier is an enumerated label value that describes the level at which the cache sits in the composable cache stack.