The Java API for the App Engine Memcache service. This offers a fast distributed cache for commonly-used data. The cache is limited both in duration and also in total space, so objects stored in it may be discarded at any time.
Note that {@code null} is a legal value to store in the cache, or to useas a cache key. Although the API is written for {@link Object}s, both keys and values should be {@link Serializable}, although future versions may someday accept specific types of non- {@code Serializable}{@code Objects}.
The values returned from this API are mutable copies from the cache; altering them has no effect upon the cached value itself until assigned with one of the {@link #put(Object,Object) put} methods. Likewise, the methodsreturning collections return mutable collections, but changes do not affect the cache.
Methods that operate on single entries, including {@link #increment}, are atomic, while batch methods such as {@link #getAll}, {@link #putAll}, and {@link #deleteAll} do not provide atomicity. Arbitrary operations on singleentries can be performed atomically by using {@link #putIfUntouched} incombination with {@link #getIdentifiable}.
{@link #increment Increment} has a number of caveats to its use; pleaseconsult the method documentation.