001/* 002 * Copyright (C) 2008 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.util.concurrent; 016 017import com.google.common.annotations.Beta; 018import com.google.common.annotations.GwtIncompatible; 019import com.google.errorprone.annotations.CanIgnoreReturnValue; 020import java.util.concurrent.CancellationException; 021import java.util.concurrent.ExecutionException; 022import java.util.concurrent.TimeUnit; 023import java.util.concurrent.TimeoutException; 024 025/** 026 * A delegating wrapper around a {@link ListenableFuture} that adds support for the {@link 027 * #checkedGet()} and {@link #checkedGet(long, TimeUnit)} methods. 028 * 029 * @author Sven Mawson 030 * @since 1.0 031 * @deprecated {@link CheckedFuture} cannot properly support the chained operations that are the 032 * primary goal of {@link ListenableFuture}. {@code CheckedFuture} also encourages users to 033 * rethrow exceptions from one thread in another thread, producing misleading stack traces. 034 * Additionally, it has a surprising policy about which exceptions to map and which to leave 035 * untouched. Guava users who want a {@code CheckedFuture} can fork the classes for their own 036 * use, possibly specializing them to the particular exception type they use. We recommend that 037 * most people use {@code ListenableFuture} and perform any exception wrapping themselves. This 038 * class is scheduled for removal from Guava in January 2019. 039 */ 040// TODO(b/72241575): Remove by 2019-01 041@Beta 042@Deprecated 043@GwtIncompatible 044public abstract class AbstractCheckedFuture<V, X extends Exception> 045 extends ForwardingListenableFuture.SimpleForwardingListenableFuture<V> 046 implements CheckedFuture<V, X> { 047 /** Constructs an {@code AbstractCheckedFuture} that wraps a delegate. */ 048 protected AbstractCheckedFuture(ListenableFuture<V> delegate) { 049 super(delegate); 050 } 051 052 /** 053 * Translates from an {@link InterruptedException}, {@link CancellationException} or {@link 054 * ExecutionException} thrown by {@code get} to an exception of type {@code X} to be thrown by 055 * {@code checkedGet}. Subclasses must implement this method. 056 * 057 * <p>If {@code e} is an {@code InterruptedException}, the calling {@code checkedGet} method has 058 * already restored the interrupt after catching the exception. If an implementation of {@link 059 * #mapException(Exception)} wishes to swallow the interrupt, it can do so by calling {@link 060 * Thread#interrupted()}. 061 * 062 * <p>Subclasses may choose to throw, rather than return, a subclass of {@code RuntimeException} 063 * to allow creating a CheckedFuture that throws both checked and unchecked exceptions. 064 */ 065 // We might like @ForOverride here, but some subclasses invoke this from their get() methods. 066 protected abstract X mapException(Exception e); 067 068 /** 069 * {@inheritDoc} 070 * 071 * <p>This implementation calls {@link #get()} and maps that method's standard exceptions to 072 * instances of type {@code X} using {@link #mapException}. 073 * 074 * <p>In addition, if {@code get} throws an {@link InterruptedException}, this implementation will 075 * set the current thread's interrupt status before calling {@code mapException}. 076 * 077 * @throws X if {@link #get()} throws an {@link InterruptedException}, {@link 078 * CancellationException}, or {@link ExecutionException} 079 */ 080 @CanIgnoreReturnValue 081 @Override 082 public V checkedGet() throws X { 083 try { 084 return get(); 085 } catch (InterruptedException e) { 086 Thread.currentThread().interrupt(); 087 throw mapException(e); 088 } catch (CancellationException | ExecutionException e) { 089 throw mapException(e); 090 } 091 } 092 093 /** 094 * {@inheritDoc} 095 * 096 * <p>This implementation calls {@link #get(long, TimeUnit)} and maps that method's standard 097 * exceptions (excluding {@link TimeoutException}, which is propagated) to instances of type 098 * {@code X} using {@link #mapException}. 099 * 100 * <p>In addition, if {@code get} throws an {@link InterruptedException}, this implementation will 101 * set the current thread's interrupt status before calling {@code mapException}. 102 * 103 * @throws X if {@link #get()} throws an {@link InterruptedException}, {@link 104 * CancellationException}, or {@link ExecutionException} 105 */ 106 @CanIgnoreReturnValue 107 @Override 108 public V checkedGet(long timeout, TimeUnit unit) throws TimeoutException, X { 109 try { 110 return get(timeout, unit); 111 } catch (InterruptedException e) { 112 Thread.currentThread().interrupt(); 113 throw mapException(e); 114 } catch (CancellationException | ExecutionException e) { 115 throw mapException(e); 116 } 117 } 118}