com.googlecode.objectify.cache

Class CachingAsyncTransaction

java.lang.Object

com.googlecode.objectify.cache.CachingAsyncDatastoreReaderWriter

com.googlecode.objectify.cache.CachingAsyncTransaction

All Implemented Interfaces:

AsyncDatastoreReaderWriter, AsyncTransaction, PrivateAsyncTransaction

public class CachingAsyncTransaction
extends CachingAsyncDatastoreReaderWriter
implements PrivateAsyncTransaction

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
CachingAsyncTransaction(AsyncTransaction raw, EntityMemcache memcache)

Method Summary

Modifier and Type	Method and Description
com.google.cloud.datastore.Transaction.Response	commit()
Future<Void>	delete(Iterable<com.google.cloud.datastore.Key> keys)
protected void	empty(Iterable<com.google.cloud.datastore.Key> keys)
void	enlist(Result<?> result)
Future<Map<com.google.cloud.datastore.Key,com.google.cloud.datastore.Entity>>	get(com.google.cloud.datastore.Key... keys) Odd that this is array and the others are iterable, but that's how the underlying API is
boolean	isActive()
void	listenForCommit(Runnable listener)
Future<List<com.google.cloud.datastore.Key>>	put(Iterable<? extends com.google.cloud.datastore.FullEntity<?>> entities)
void	rollback()
<T> com.google.cloud.datastore.QueryResults<T>	run(com.google.cloud.datastore.Query<T> query)
void	runCommitListeners()

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, put

Constructor Detail

CachingAsyncTransaction

public CachingAsyncTransaction(AsyncTransaction raw,
                               EntityMemcache memcache)

Method Detail

empty

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

Specified by:

empty in class CachingAsyncDatastoreReaderWriter

commit

public com.google.cloud.datastore.Transaction.Response commit()

Specified by:

commit in interface AsyncTransaction

isActive

public boolean isActive()

Specified by:

isActive in interface AsyncTransaction

rollback

public void rollback()

Specified by:

rollback in interface AsyncTransaction

listenForCommit

public void listenForCommit(Runnable listener)

Specified by:

listenForCommit in interface AsyncTransaction

runCommitListeners

public void runCommitListeners()

Specified by:

runCommitListeners in interface PrivateAsyncTransaction

enlist

public void enlist(Result<?> result)

Specified by:

enlist in interface PrivateAsyncTransaction

delete

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

Specified by:

delete in interface AsyncDatastoreReaderWriter

Overrides:

delete in class CachingAsyncDatastoreReaderWriter

get

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

Description copied from interface: AsyncDatastoreReaderWriter

Odd that this is array and the others are iterable, but that's how the underlying API is

Specified by:

get 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

Overrides:

run in class CachingAsyncDatastoreReaderWriter

put

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

Specified by:

put in interface AsyncDatastoreReaderWriter

Overrides:

put in class CachingAsyncDatastoreReaderWriter