Package com.google.common.util.concurrent

Class ClosingFuture.Combiner

java.lang.Object

com.google.common.util.concurrent.ClosingFuture.Combiner

Direct Known Subclasses:

ClosingFuture.Combiner2, ClosingFuture.Combiner3, ClosingFuture.Combiner4, ClosingFuture.Combiner5

Enclosing class:

ClosingFuture<V>

public static class ClosingFuture.Combiner
extends java.lang.Object

A builder of a ClosingFuture step that is derived from more than one input step.

See ClosingFuture.whenAllComplete(Iterable) and ClosingFuture.whenAllSucceed(Iterable) for how to instantiate this class.

Example:

 final ClosingFuture<BufferedReader> file1ReaderFuture = ...;
 final ClosingFuture<BufferedReader> file2ReaderFuture = ...;
 ListenableFuture<Integer> numberOfDifferentLines =
       ClosingFuture.whenAllSucceed(file1ReaderFuture, file2ReaderFuture)
           .call(
               (closer, peeker) -> {
                 BufferedReader file1Reader = peeker.getDone(file1ReaderFuture);
                 BufferedReader file2Reader = peeker.getDone(file2ReaderFuture);
                 return countDifferentLines(file1Reader, file2Reader);
               },
               executor)
           .closing(executor);
 

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	ClosingFuture.Combiner.AsyncCombiningCallable<V>	An operation that returns a ClosingFuture result and may throw an exception.
static interface	ClosingFuture.Combiner.CombiningCallable<V>	An operation that returns a result and may throw an exception.

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	allMustSucceed
private ClosingFuture.CloseableList	closeables
private static Function<ClosingFuture<?>,FluentFuture<?>>	INNER_FUTURE
protected ImmutableList<ClosingFuture<?>>	inputs

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Combiner(boolean allMustSucceed, java.lang.Iterable<? extends ClosingFuture<?>> inputs)

Method Summary

Modifier and Type	Method	Description
<V> ClosingFuture<V>	call(ClosingFuture.Combiner.CombiningCallable<V> combiningCallable, java.util.concurrent.Executor executor)	Returns a new ClosingFuture pipeline step derived from the inputs by applying a combining function to their values.
<V> ClosingFuture<V>	callAsync(ClosingFuture.Combiner.AsyncCombiningCallable<V> combiningCallable, java.util.concurrent.Executor executor)	Returns a new ClosingFuture pipeline step derived from the inputs by applying a ClosingFuture-returning function to their values.
private Futures.FutureCombiner<java.lang.Object>	futureCombiner()
private ImmutableList<FluentFuture<?>>	inputFutures()

Methods inherited from class java.lang.Object

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

Field Detail

closeables

private final ClosingFuture.CloseableList closeables

allMustSucceed

private final boolean allMustSucceed

inputs

protected final ImmutableList<ClosingFuture<?>> inputs

INNER_FUTURE

private static final Function<ClosingFuture<?>,FluentFuture<?>> INNER_FUTURE

Constructor Detail

Combiner

private Combiner(boolean allMustSucceed,
                 java.lang.Iterable<? extends ClosingFuture<?>> inputs)

Method Detail

call

public <V> ClosingFuture<V> call(ClosingFuture.Combiner.CombiningCallable<V> combiningCallable,
                                 java.util.concurrent.Executor executor)

Returns a new ClosingFuture pipeline step derived from the inputs by applying a combining function to their values. The function can use a ClosingFuture.DeferredCloser to capture objects to be closed when the pipeline is done.

If this combiner was returned by a ClosingFuture.whenAllSucceed(java.lang.Iterable<? extends com.google.common.util.concurrent.ClosingFuture<?>>) method and any of the inputs fail, so will the returned step.

If the combiningCallable throws a CancellationException, the pipeline will be cancelled.

If the combiningCallable throws an ExecutionException, the cause of the thrown ExecutionException will be extracted and used as the failure of the derived step.

callAsync

public <V> ClosingFuture<V> callAsync(ClosingFuture.Combiner.AsyncCombiningCallable<V> combiningCallable,
                                      java.util.concurrent.Executor executor)

Returns a new ClosingFuture pipeline step derived from the inputs by applying a ClosingFuture-returning function to their values. The function can use a ClosingFuture.DeferredCloser to capture objects to be closed when the pipeline is done (other than those captured by the returned ClosingFuture).

If this combiner was returned by a ClosingFuture.whenAllSucceed(java.lang.Iterable<? extends com.google.common.util.concurrent.ClosingFuture<?>>) method and any of the inputs fail, so will the returned step.

If the combiningCallable throws a CancellationException, the pipeline will be cancelled.

If the combiningCallable throws an ExecutionException, the cause of the thrown ExecutionException will be extracted and used as the failure of the derived step.

If the combiningCallable throws any other exception, it will be used as the failure of the derived step.

If an exception is thrown after the combiningCallable creates a ClosingFuture, then none of the closeable objects in that ClosingFuture will be closed.

Usage guidelines for this method:

• Use this method only when calling an API that returns a ListenableFuture or a ClosingFuture. If possible, prefer calling call(CombiningCallable, Executor) instead, with a function that returns the next value directly.
• Call closer.eventuallyClose() for every closeable object this step creates in order to capture it for later closing.
• Return a ClosingFuture. To turn a ListenableFuture into a ClosingFuture call ClosingFuture.from(ListenableFuture).

The same warnings about doing heavyweight operations within ClosingFuture.transformAsync(AsyncClosingFunction, Executor) apply here.

futureCombiner

private Futures.FutureCombiner<java.lang.Object> futureCombiner()

inputFutures

private ImmutableList<FluentFuture<?>> inputFutures()