Package com.tangosol.util.aggregator

Class AsynchronousAggregator<K,V,P,R>

java.lang.Object

com.tangosol.util.AsynchronousAgent<R>

com.tangosol.util.aggregator.AbstractAsynchronousAggregator<K,V,P,R>

com.tangosol.util.aggregator.AsynchronousAggregator<K,V,P,R>

Type Parameters:

K - the type of the Map entry keys

V - the type of the Map entry values

P - the type of the intermediate result during the parallel stage

R - the type of the value returned by the StreamingAggregator

All Implemented Interfaces:

FlowControl, InvocableMap.EntryAggregator<K,V,R>, Serializable, Future<R>

public class AsynchronousAggregator<K,V,P,R>
extends AbstractAsynchronousAggregator<K,V,P,R>
implements InvocableMap.EntryAggregator<K,V,R>

A marker EntryAggregator wrapper class that allows for an asynchronous invocation of the underlying aggregator. When used as a Future (without extending), this implementation will simply provide the result of asynchronous streaming aggregation according to semantics of the corresponding EntryAggregator.aggregate contract.

More advanced use would require extending this class and overriding onResult(P) and onException(java.lang.Throwable) methods. It's very important that overriding implementations of these methods must be non-blocking. For example, any use of NamedCache API is completely disallowed with the only exception of AsynchronousAggregators and AsynchronousProcessor(InvocableMap.EntryProcessor)

The underlying entry processor is guaranteed to have been fully executed when either onResult() or onException() are called.

Note 1: Neither this class nor its extensions need to be serializable. Only the underlying aggregator is serialized and sent to corresponding servers for execution.
Note 2: This feature is not available on Coherence*Extend clients.

Author:

gg/mf 2012.12.21

See Also:

• AsynchronousProcessor
• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.concurrent.Future

Future.State

Field Summary

Fields

Modifier and Type	Field	Description
protected Throwable	m_eReason	Reason for the failed operation.

Fields inherited from class com.tangosol.util.aggregator.AbstractAsynchronousAggregator

m_aggregator

Fields inherited from class com.tangosol.util.AsynchronousAgent

m_control, m_iOrderId

Constructor Summary

Constructors

Constructor	Description
AsynchronousAggregator(InvocableMap.StreamingAggregator<K,V,P,R> aggregator)	Construct an AsynchronousAggregator for a given streaming aggregator.
AsynchronousAggregator(InvocableMap.StreamingAggregator<K,V,P,R> aggregator, int iUnitOrderId)	Construct an AsynchronousAggregator for a given streaming aggregator.

Method Summary

Modifier and Type	Method	Description
void	onComplete()	Called after this asynchronous aggregator has been notified about all possible partial results or failures and no more are forthcoming.
void	onException(Throwable eReason)	Called if the operation failed for any reason.
void	onResult(P result)	Called when the aggregation result is available.

Methods inherited from class com.tangosol.util.aggregator.AbstractAsynchronousAggregator

aggregate, getAggregator, getUnitOfOrderId

Methods inherited from class com.tangosol.util.AsynchronousAgent

bind, cancel, checkBacklog, complete, completeExceptionally, drainBacklog, flush, get, get, getCompletableFuture, getException, getResult, isCancelled, isCompletedExceptionally, isDone

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.concurrent.Future

exceptionNow, resultNow, state

Methods inherited from interface com.tangosol.util.InvocableMap.EntryAggregator

aggregate

Field Details

m_eReason

protected volatile Throwable m_eReason

Reason for the failed operation.

Constructor Details

AsynchronousAggregator

public AsynchronousAggregator(InvocableMap.StreamingAggregator<K,V,P,R> aggregator)

Construct an AsynchronousAggregator for a given streaming aggregator.

Parameters:

aggregator - the underlying streaming aggregator

AsynchronousAggregator

public AsynchronousAggregator(InvocableMap.StreamingAggregator<K,V,P,R> aggregator,
 int iUnitOrderId)

Construct an AsynchronousAggregator for a given streaming aggregator.

Parameters:

aggregator - the underlying streaming aggregator

iUnitOrderId - the unit-of-order id for this aggregator

Method Details

onResult

public void onResult(P result)

Called when the aggregation result is available.

For ordering guarantees see AbstractAsynchronousAggregator.getUnitOfOrderId().

Note: Overriding implementations of this method must be non-blocking.

Specified by:

onResult in class AbstractAsynchronousAggregator<K,V,P,R>

Parameters:

result - the result

onException

public void onException(Throwable eReason)

Called if the operation failed for any reason.

Note: Overriding implementations of this method must be non-blocking.

Specified by:

onException in class AbstractAsynchronousAggregator<K,V,P,R>

Parameters:

eReason - the reason of failure

onComplete

public void onComplete()

Description copied from class: AbstractAsynchronousAggregator

Called after this asynchronous aggregator has been notified about all possible partial results or failures and no more are forthcoming.

As long as this aggregator was submitted to any of InvocableMap's methods, this method is guaranteed to be called once and only once.

Possible call back sequences are:

  cache.aggregate
    ...
    onResult
    onComplete

  cache.aggregate
    ...
    onException
    onComplete

  cache.aggregate
    ...
     onResult
     onException
     onException
     onResult
     onComplete
 

For ordering guarantees across processors see AbstractAsynchronousAggregator.getUnitOfOrderId().

Note:

Overriding implementations of this method must be non-blocking.

If the StreamingAggregator signaled to short-circuit the aggregation while combining partial results, onComplete() could be called before all the results are received.

Specified by:

onComplete in class AbstractAsynchronousAggregator<K,V,P,R>