Struct ExpirationCache

tools/cache/expiration_cache.go:38–46

ExpirationCache implements the store interface 1. All entries are automatically time stamped on insert a. The key is computed based off the original item/keyFunc b. The value inserted under that key is the timestamped item 2. Expiration happens lazily on read based on the expiration policy a.

// threadSafeStore because it takes a write lock every time it checks if
// an item has expired.
type ExpirationCache struct {
	cacheStorage     ThreadSafeStore
	keyFunc          KeyFunc
	clock            clock.Clock
	expirationPolicy ExpirationPolicy
	// expirationLock is a write lock used to guarantee that we don't clobber
	// newly inserted objects because of a stale expiration timestamp comparison
	expirationLock sync.Mutex
}

// ExpirationPolicy dictates when an object expires. Currently only abstracted out
// so unittests don't rely on the system clock.