/*
* 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 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
*/
@Beta
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.
*/
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}
*/
@Override
public V checkedGet() throws X {
try {
return get();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw mapException(e);
} catch (CancellationException e) {
throw mapException(e);
} catch (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}
* @throws TimeoutException {@inheritDoc}
*/
@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 e) {
throw mapException(e);
} catch (ExecutionException e) {
throw mapException(e);
}
}
}
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