001/* 002 * Copyright (C) 2018 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.internal; 016 017 018/** 019 * Static utilities for {@link InternalFutureFailureAccess}. Most users will never need to use this 020 * class. 021 * 022 * <p>This class is GWT-compatible. 023 * 024 * @since {@code com.google.guava:failureaccess:1.0}, which was added as a dependency of Guava in 025 * Guava 27.0 026 */ 027public final class InternalFutures { 028 /** 029 * Usually returns {@code null} but, if the given {@code Future} has failed, may <i>optionally</i> 030 * return the cause of the failure. "Failure" means specifically "completed with an exception"; it 031 * does not include "was cancelled." To be explicit: If this method returns a non-null value, 032 * then: 033 * 034 * <ul> 035 * <li>{@code isDone()} must return {@code true} 036 * <li>{@code isCancelled()} must return {@code false} 037 * <li>{@code get()} must not block, and it must throw an {@code ExecutionException} with the 038 * return value of this method as its cause 039 * </ul> 040 */ 041 public static 042 Throwable tryInternalFastPathGetFailure(InternalFutureFailureAccess future) { 043 return future.tryInternalFastPathGetFailure(); 044 } 045 046 private InternalFutures() {} 047}