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/*
* Copyright (C) 2008 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.common.util.concurrent;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* A delegating wrapper around a {@link ListenableFuture} that adds support for the {@link
* #checkedGet()} and {@link #checkedGet(long, TimeUnit)} methods.
*
* @author Sven Mawson
* @since 1.0
* @deprecated {@link CheckedFuture} cannot properly support the chained operations that are the
* primary goal of {@link ListenableFuture}. {@code CheckedFuture} also encourages users to
* rethrow exceptions from one thread in another thread, producing misleading stack traces.
* Additionally, it has a surprising policy about which exceptions to map and which to leave
* untouched. Guava users who want a {@code CheckedFuture} can fork the classes for their own
* use, possibly specializing them to the particular exception type they use. We recommend that
* most people use {@code ListenableFuture} and perform any exception wrapping themselves. This
* class is scheduled for removal from Guava in January 2019.
*/
// TODO(b/72241575): Remove by 2019-01
@Beta
@Deprecated
@GwtIncompatible
public abstract class AbstractCheckedFuture<V, X extends Exception>
extends ForwardingListenableFuture.SimpleForwardingListenableFuture<V>
implements CheckedFuture<V, X> {
/** Constructs an {@code AbstractCheckedFuture} that wraps a delegate. */
protected AbstractCheckedFuture(ListenableFuture<V> delegate) {
super(delegate);
}
/**
* Translates from an {@link InterruptedException}, {@link CancellationException} or {@link
* ExecutionException} thrown by {@code get} to an exception of type {@code X} to be thrown by
* {@code checkedGet}. Subclasses must implement this method.
*
* <p>If {@code e} is an {@code InterruptedException}, the calling {@code checkedGet} method has
* already restored the interrupt after catching the exception. If an implementation of {@link
* #mapException(Exception)} wishes to swallow the interrupt, it can do so by calling {@link
* Thread#interrupted()}.
*
* <p>Subclasses may choose to throw, rather than return, a subclass of {@code RuntimeException}
* to allow creating a CheckedFuture that throws both checked and unchecked exceptions.
*/
// We might like @ForOverride here, but some subclasses invoke this from their get() methods.
protected abstract X mapException(Exception e);
/**
* {@inheritDoc}
*
* <p>This implementation calls {@link #get()} and maps that method's standard exceptions to
* instances of type {@code X} using {@link #mapException}.
*
* <p>In addition, if {@code get} throws an {@link InterruptedException}, this implementation will
* set the current thread's interrupt status before calling {@code mapException}.
*
* @throws X if {@link #get()} throws an {@link InterruptedException}, {@link
* CancellationException}, or {@link ExecutionException}
*/
@CanIgnoreReturnValue
@Override
public V checkedGet() throws X {
try {
return get();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw mapException(e);
} catch (CancellationException | ExecutionException e) {
throw mapException(e);
}
}
/**
* {@inheritDoc}
*
* <p>This implementation calls {@link #get(long, TimeUnit)} and maps that method's standard
* exceptions (excluding {@link TimeoutException}, which is propagated) to instances of type
* {@code X} using {@link #mapException}.
*
* <p>In addition, if {@code get} throws an {@link InterruptedException}, this implementation will
* set the current thread's interrupt status before calling {@code mapException}.
*
* @throws X if {@link #get()} throws an {@link InterruptedException}, {@link
* CancellationException}, or {@link ExecutionException}
*/
@CanIgnoreReturnValue
@Override
public V checkedGet(long timeout, TimeUnit unit) throws TimeoutException, X {
try {
return get(timeout, unit);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw mapException(e);
} catch (CancellationException | ExecutionException e) {
throw mapException(e);
}
}
}
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