NewCachedBlobStatter creates a new statter which prefers a cache and falls back to a backend.

NewCachedBlobStatterWithMetrics creates a new statter which prefers a cache and falls back to a backend.

ValidateDescriptor provides a helper function to ensure that caches have common criteria for admitting descriptors.

Metrics is used to hold metric counters related to the number of times a cache was hit or missed.

BlobDescriptorCacheProvider provides repository scoped BlobDescriptorService cache instances and a global descriptor cache.

Logger can be provided on the MetricsTracker to log errors.

MetricsTracker represents a metric tracker which simply counts the number of hits and misses.