Package org.apache.hadoop.hbase.util

Class FutureUtils

java.lang.Object

org.apache.hadoop.hbase.util.FutureUtils

@Private
public final class FutureUtils
extends Object

Helper class for processing futures.

Field Summary

Fields

Modifier and Type	Field	Description
private static final org.slf4j.Logger	LOG

Constructor Summary

Constructors

Modifier	Constructor	Description
private	FutureUtils()

Method Summary

Modifier and Type	Method	Description
static <T> void	addListener(CompletableFuture<T> future, BiConsumer<? super T,? super Throwable> action)	This is method is used when you just want to add a listener to the given future.
static <T> void	addListener(CompletableFuture<T> future, BiConsumer<? super T,? super Throwable> action, Executor executor)	Almost the same with addListener(CompletableFuture, BiConsumer) method above, the only exception is that we will call CompletableFuture.whenCompleteAsync(BiConsumer, Executor).
static <T> CompletableFuture<List<T>>	allOf(List<CompletableFuture<T>> futures)	Returns a new CompletableFuture that is completed when all of the given CompletableFutures complete.
static void	consume(CompletableFuture<?> future)	Log the error if the future indicates any failure.
static <T> CompletableFuture<T>	failedFuture(Throwable e)	Returns a CompletableFuture that is already completed exceptionally with the given exception.
static <T> T	get(Future<T> future)	A helper class for getting the result of a Future, and convert the error to an IOException.
static <T> T	get(Future<T> future, long timeout, TimeUnit unit)	A helper class for getting the result of a Future with timeout, and convert the error to an IOException.
static IOException	rethrow(Throwable error)	If we could propagate the given error directly, we will fill the stack trace with the current thread's stack trace so it is easier to trace where is the exception thrown.
private static void	setStackTrace(Throwable error)
static Throwable	unwrapCompletionException(Throwable error)	Get the cause of the Throwable if it is a CompletionException.
static <T> CompletableFuture<T>	wrapFuture(CompletableFuture<T> future, Executor executor)	Return a CompletableFuture which is same with the given future, but execute all the callbacks in the given executor.

Methods inherited from class java.lang.Object

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

Field Details

LOG

private static final org.slf4j.Logger LOG

Constructor Details

FutureUtils

private FutureUtils()

Method Details

addListener

public static <T> void addListener(CompletableFuture<T> future,
 BiConsumer<? super T,? super Throwable> action)

This is method is used when you just want to add a listener to the given future. We will call CompletableFuture.whenComplete(BiConsumer) to register the action to the future. Ignoring the return value of a Future is considered as a bad practice as it may suppress exceptions thrown from the code that completes the future, and this method will catch all the exception thrown from the action to catch possible code bugs.

And the error phone check will always report FutureReturnValueIgnored because every method in the CompletableFuture class will return a new CompletableFuture, so you always have one future that has not been checked. So we introduce this method and add a suppress warnings annotation here.

addListener

public static <T> void addListener(CompletableFuture<T> future,
 BiConsumer<? super T,? super Throwable> action,
 Executor executor)

Almost the same with addListener(CompletableFuture, BiConsumer) method above, the only exception is that we will call CompletableFuture.whenCompleteAsync(BiConsumer, Executor).

See Also:

• addListener(CompletableFuture, BiConsumer)

consume

public static void consume(CompletableFuture<?> future)

Log the error if the future indicates any failure.

wrapFuture

public static <T> CompletableFuture<T> wrapFuture(CompletableFuture<T> future,
 Executor executor)

Return a CompletableFuture which is same with the given future, but execute all the callbacks in the given executor.

unwrapCompletionException

public static Throwable unwrapCompletionException(Throwable error)

Get the cause of the Throwable if it is a CompletionException.

setStackTrace

private static void setStackTrace(Throwable error)

rethrow

public static IOException rethrow(Throwable error)
                           throws IOException

If we could propagate the given error directly, we will fill the stack trace with the current thread's stack trace so it is easier to trace where is the exception thrown. If not, we will just create a new IOException and then throw it.

Throws:

IOException

get

public static <T> T get(Future<T> future)
                 throws IOException

A helper class for getting the result of a Future, and convert the error to an IOException.

Throws:

IOException

get

public static <T> T get(Future<T> future,
 long timeout,
 TimeUnit unit)
                 throws IOException

A helper class for getting the result of a Future with timeout, and convert the error to an IOException.

Throws:

IOException

failedFuture

public static <T> CompletableFuture<T> failedFuture(Throwable e)

Returns a CompletableFuture that is already completed exceptionally with the given exception.

allOf

public static <T> CompletableFuture<List<T>> allOf(List<CompletableFuture<T>> futures)

Returns a new CompletableFuture that is completed when all of the given CompletableFutures complete. If any of the given CompletableFutures complete exceptionally, then the returned CompletableFuture also does so, with a CompletionException holding this exception as its cause. Otherwise, the results of all given CompletableFutures could be obtained by the new returned CompletableFuture.