org.apache.kafka.common

Class KafkaFuture<T>

java.lang.Object

org.apache.kafka.common.KafkaFuture<T>

All Implemented Interfaces:

Future<T>

public abstract class KafkaFuture<T>
extends Object
implements Future<T>

A flexible future which supports call chaining and other asynchronous programming patterns.

Relation to CompletionStage

It is possible to obtain a CompletionStage from a KafkaFuture instance by calling toCompletionStage(). If converting whenComplete(BiConsumer) or thenApply(BaseFunction) to CompletableFuture.whenComplete(java.util.function.BiConsumer) or CompletableFuture.thenApply(java.util.function.Function) be aware that the returned KafkaFuture will fail with an ExecutionException, whereas a CompletionStage fails with a CompletionException.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	KafkaFuture.BaseFunction<A,B> A function which takes objects of type A and returns objects of type B.
static interface	KafkaFuture.BiConsumer<A,B> A consumer of two different types of object.
static class	KafkaFuture.Function<A,B> Deprecated. Since Kafka 3.0. Use the KafkaFuture.BaseFunction functional interface.

Constructor Summary

Constructors

Constructor and Description
KafkaFuture()

Method Summary

Modifier and Type	Method and Description
static KafkaFuture<Void>	allOf(KafkaFuture<?>... futures) Returns a new KafkaFuture that is completed when all the given futures have completed.
abstract boolean	cancel(boolean mayInterruptIfRunning) If not already completed, completes this future with a CancellationException.
protected abstract boolean	complete(T newValue) If not already completed, sets the value returned by get() and related methods to the given value.
static <U> KafkaFuture<U>	completedFuture(U value) Returns a new KafkaFuture that is already completed with the given value.
protected abstract boolean	completeExceptionally(Throwable newException) If not already completed, causes invocations of get() and related methods to throw the given exception.
abstract T	get() Waits if necessary for this future to complete, and then returns its result.
abstract T	get(long timeout, TimeUnit unit) Waits if necessary for at most the given time for this future to complete, and then returns its result, if available.
abstract T	getNow(T valueIfAbsent) Returns the result value (or throws any encountered exception) if completed, else returns the given valueIfAbsent.
abstract boolean	isCancelled() Returns true if this CompletableFuture was cancelled before it completed normally.
abstract boolean	isCompletedExceptionally() Returns true if this CompletableFuture completed exceptionally, in any way.
abstract boolean	isDone() Returns true if completed in any fashion: normally, exceptionally, or via cancellation.
abstract <R> KafkaFuture<R>	thenApply(KafkaFuture.BaseFunction<T,R> function) Returns a new KafkaFuture that, when this future completes normally, is executed with this futures's result as the argument to the supplied function.
abstract <R> KafkaFuture<R>	thenApply(KafkaFuture.Function<T,R> function) Prefer thenApply(BaseFunction) as this function is here for backwards compatibility reasons and might be deprecated/removed in a future release.
abstract CompletionStage<T>	toCompletionStage() Gets a CompletionStage with the same completion properties as this KafkaFuture.
abstract KafkaFuture<T>	whenComplete(KafkaFuture.BiConsumer<? super T,? super Throwable> action) Returns a new KafkaFuture with the same result or exception as this future, that executes the given action when this future completes.

Methods inherited from class java.lang.Object

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

Constructor Detail

KafkaFuture

public KafkaFuture()

Method Detail

completedFuture

public static <U> KafkaFuture<U> completedFuture(U value)

Returns a new KafkaFuture that is already completed with the given value.

allOf

public static KafkaFuture<Void> allOf(KafkaFuture<?>... futures)

Returns a new KafkaFuture that is completed when all the given futures have completed. If any future throws an exception, the returned future returns it. If multiple futures throw an exception, which one gets returned is arbitrarily chosen.

toCompletionStage

public abstract CompletionStage<T> toCompletionStage()

Gets a CompletionStage with the same completion properties as this KafkaFuture. The returned instance will complete when this future completes and in the same way (with the same result or exception).

Calling toCompletableFuture() on the returned instance will yield a CompletableFuture, but invocation of the completion methods (complete() and other methods in the complete*() and obtrude*() families) on that CompletableFuture instance will result in UnsupportedOperationException being thrown. Unlike a "minimal" CompletableFuture, the get*() and other methods of CompletableFuture that are not inherited from CompletionStage will work normally.

If you want to block on the completion of a KafkaFuture you should use get(), get(long, TimeUnit) or getNow(Object), rather than calling .toCompletionStage().toCompletableFuture().get() etc.

Since:

Kafka 3.0

thenApply

public abstract <R> KafkaFuture<R> thenApply(KafkaFuture.BaseFunction<T,R> function)

Returns a new KafkaFuture that, when this future completes normally, is executed with this futures's result as the argument to the supplied function. The function may be invoked by the thread that calls thenApply or it may be invoked by the thread that completes the future.

thenApply

public abstract <R> KafkaFuture<R> thenApply(KafkaFuture.Function<T,R> function)

Prefer thenApply(BaseFunction) as this function is here for backwards compatibility reasons and might be deprecated/removed in a future release.

whenComplete

public abstract KafkaFuture<T> whenComplete(KafkaFuture.BiConsumer<? super T,? super Throwable> action)

Returns a new KafkaFuture with the same result or exception as this future, that executes the given action when this future completes. When this future is done, the given action is invoked with the result (or null if none) and the exception (or null if none) of this future as arguments. The returned future is completed when the action returns. The supplied action should not throw an exception. However, if it does, the following rules apply: if this future completed normally but the supplied action throws an exception, then the returned future completes exceptionally with the supplied action's exception. Or, if this future completed exceptionally and the supplied action throws an exception, then the returned future completes exceptionally with this future's exception. The action may be invoked by the thread that calls whenComplete or it may be invoked by the thread that completes the future.

Parameters:

action - the action to preform

Returns:

the new future

complete

protected abstract boolean complete(T newValue)

If not already completed, sets the value returned by get() and related methods to the given value.

completeExceptionally

protected abstract boolean completeExceptionally(Throwable newException)

If not already completed, causes invocations of get() and related methods to throw the given exception.

cancel

public abstract boolean cancel(boolean mayInterruptIfRunning)

If not already completed, completes this future with a CancellationException. Dependent futures that have not already completed will also complete exceptionally, with a CompletionException caused by this CancellationException.

Specified by:

cancel in interface Future<T>

get

public abstract T get()
               throws InterruptedException,
                      ExecutionException

Waits if necessary for this future to complete, and then returns its result.

Specified by:

get in interface Future<T>

Throws:

InterruptedException

ExecutionException

get

public abstract T get(long timeout,
                      TimeUnit unit)
               throws InterruptedException,
                      ExecutionException,
                      TimeoutException

Waits if necessary for at most the given time for this future to complete, and then returns its result, if available.

Specified by:

get in interface Future<T>

Throws:

InterruptedException

ExecutionException

TimeoutException

getNow

public abstract T getNow(T valueIfAbsent)
                  throws InterruptedException,
                         ExecutionException

Returns the result value (or throws any encountered exception) if completed, else returns the given valueIfAbsent.

Throws:

InterruptedException

ExecutionException

isCancelled

public abstract boolean isCancelled()

Returns true if this CompletableFuture was cancelled before it completed normally.

Specified by:

isCancelled in interface Future<T>

isCompletedExceptionally

public abstract boolean isCompletedExceptionally()

Returns true if this CompletableFuture completed exceptionally, in any way.

isDone

public abstract boolean isDone()

Returns true if completed in any fashion: normally, exceptionally, or via cancellation.

Specified by:

isDone in interface Future<T>