Package com.googlecode.objectify.cache

Class CachingAsyncDatastore

java.lang.Object

com.googlecode.objectify.cache.CachingAsyncDatastoreReaderWriter

com.googlecode.objectify.cache.CachingAsyncDatastore

All Implemented Interfaces:

AsyncDatastore, AsyncDatastoreReaderWriter

public class CachingAsyncDatastore
extends CachingAsyncDatastoreReaderWriter
implements AsyncDatastore

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 <[email protected]>

Constructor Summary

Constructors

Constructor	Description
CachingAsyncDatastore(AsyncDatastore raw, EntityMemcache memcache)

Method Summary

Modifier and Type	Method	Description
protected void	empty(Iterable<com.google.cloud.datastore.Key> keys)
Future<Map<com.google.cloud.datastore.Key,com.google.cloud.datastore.Entity>>	get(Collection<com.google.cloud.datastore.Key> keys, com.google.cloud.datastore.ReadOption... options)
AsyncTransaction	newTransaction(TxnOptions options, Runnable afterCommit, Optional<com.google.protobuf.ByteString> prevTxnHandle)

Methods inherited from class com.googlecode.objectify.cache.CachingAsyncDatastoreReaderWriter

delete, put, run, run, runAggregation

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.AsyncDatastore

newTransaction, newTransaction

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

delete, get, put, put, run, run, runAggregation

Constructor Details

CachingAsyncDatastore

public CachingAsyncDatastore(AsyncDatastore raw,
 EntityMemcache memcache)

Method Details

empty

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

Specified by:

empty in class CachingAsyncDatastoreReaderWriter

newTransaction

public AsyncTransaction newTransaction(TxnOptions options,
 Runnable afterCommit,
 Optional<com.google.protobuf.ByteString> prevTxnHandle)

Specified by:

newTransaction in interface AsyncDatastore

get

public Future<Map<com.google.cloud.datastore.Key,com.google.cloud.datastore.Entity>> get(Collection<com.google.cloud.datastore.Key> keys,
 com.google.cloud.datastore.ReadOption... options)

Specified by:

get in interface AsyncDatastoreReaderWriter