com.googlecode.objectify.cache

Class CachingAsyncDatastoreReaderWriter

java.lang.Object

com.googlecode.objectify.cache.CachingAsyncDatastoreReaderWriter

All Implemented Interfaces:

AsyncDatastoreReaderWriter

Direct Known Subclasses:

CachingAsyncDatastore, CachingAsyncTransaction

public abstract class CachingAsyncDatastoreReaderWriter
extends Object
implements AsyncDatastoreReaderWriter

A write-through memcache for Entity objects that works for both transactional and nontransactional sessions.

• Caches negative results as well as positive results.
• Queries do not affect the cache in any way.
• Transactional reads bypass the cache, but successful transaction commits will update the cache.
• This cache has near-transactional integrity. As long as DeadlineExceededException is not hit, cache should not go out of sync even under heavy contention.

Note: Until Google adds a hook that lets us wrap native Future implementations, you muse install the AsyncCacheFilter to use this cache asynchronously. This is not necessary for synchronous use of CachingDatastoreService, but asynchronous operation requires an extra hook for the end of a request when fired-and-forgotten put()s and delete()s get processed. If you use this cache asynchronously, and you do not use the AsyncCacheFilter, your cache will go out of sync.

Author:

Jeff Schnitzer

Constructor Summary

Constructors

Constructor and Description
CachingAsyncDatastoreReaderWriter()

Method Summary

Modifier and Type	Method and Description
Future<Void>	delete(Iterable<com.google.cloud.datastore.Key> keys)
protected abstract void	empty(Iterable<com.google.cloud.datastore.Key> keys)
Future<List<com.google.cloud.datastore.Key>>	put(Iterable<? extends com.google.cloud.datastore.FullEntity<?>> entities)
<T> com.google.cloud.datastore.QueryResults<T>	run(com.google.cloud.datastore.Query<T> query)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.googlecode.objectify.impl.AsyncDatastoreReaderWriter

get, get, put

Constructor Detail

CachingAsyncDatastoreReaderWriter

public CachingAsyncDatastoreReaderWriter()

Method Detail

empty

protected abstract void empty(Iterable<com.google.cloud.datastore.Key> keys)

delete

public Future<Void> delete(Iterable<com.google.cloud.datastore.Key> keys)

Specified by:

delete in interface AsyncDatastoreReaderWriter

run

public <T> com.google.cloud.datastore.QueryResults<T> run(com.google.cloud.datastore.Query<T> query)

Specified by:

run in interface AsyncDatastoreReaderWriter

put

public Future<List<com.google.cloud.datastore.Key>> put(Iterable<? extends com.google.cloud.datastore.FullEntity<?>> entities)

Specified by:

put in interface AsyncDatastoreReaderWriter