46 lines
1.3 KiB
Scala
46 lines
1.3 KiB
Scala
package com.twitter.tweetypie.caching
|
|
|
|
/**
|
|
* Encodes the possible states of a value loaded from memcached.
|
|
*
|
|
* @see [[ValueSerializer]] and [[CacheOperations]]
|
|
*/
|
|
sealed trait CacheResult[+V]
|
|
|
|
object CacheResult {
|
|
|
|
/**
|
|
* Signals that the value could not be successfully loaded from
|
|
* cache. `Failure` values should not be written back to cache.
|
|
*
|
|
* This value may result from an error talking to the memcached
|
|
* instance or it may be returned from the Serializer when the value
|
|
* should not be reused, but should also not be overwritten.
|
|
*/
|
|
final case class Failure(e: Throwable) extends CacheResult[Nothing]
|
|
|
|
/**
|
|
* Signals that the cache load attempt was successful, but there was
|
|
* not a usable value.
|
|
*
|
|
* When processing a `Miss`, the value should be written back to
|
|
* cache if it loads successfully.
|
|
*/
|
|
case object Miss extends CacheResult[Nothing]
|
|
|
|
/**
|
|
* Signals that the value was found in cache.
|
|
*
|
|
* It is not necessary to load the value from the original source.
|
|
*/
|
|
case class Fresh[V](value: V) extends CacheResult[V]
|
|
|
|
/**
|
|
* Signals that the value was found in cache.
|
|
*
|
|
* This value should be used, but it should be refreshed
|
|
* out-of-band.
|
|
*/
|
|
case class Stale[V](value: V) extends CacheResult[V]
|
|
}
|