Java tutorial
/* * Copyright 2016 The Netty Project * * The Netty Project licenses this file to you 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 io.netty.util.internal; import io.netty.util.concurrent.Promise; import io.netty.util.internal.logging.InternalLogger; /** * Internal utilities to notify {@link Promise}s. */ public final class PromiseNotificationUtil { private PromiseNotificationUtil() { } /** * Try to cancel the {@link Promise} and log if {@code logger} is not {@code null} in case this fails. */ public static void tryCancel(Promise<?> p, InternalLogger logger) { if (!p.cancel(false) && logger != null) { Throwable err = p.cause(); if (err == null) { logger.warn("Failed to cancel promise because it has succeeded already: {}", p); } else { logger.warn("Failed to cancel promise because it has failed already: {}, unnotified cause:", p, err); } } } /** * Try to mark the {@link Promise} as success and log if {@code logger} is not {@code null} in case this fails. */ public static <V> void trySuccess(Promise<? super V> p, V result, InternalLogger logger) { if (!p.trySuccess(result) && logger != null) { Throwable err = p.cause(); if (err == null) { logger.warn("Failed to mark a promise as success because it has succeeded already: {}", p); } else { logger.warn( "Failed to mark a promise as success because it has failed already: {}, unnotified cause:", p, err); } } } /** * Try to mark the {@link Promise} as failure and log if {@code logger} is not {@code null} in case this fails. */ public static void tryFailure(Promise<?> p, Throwable cause, InternalLogger logger) { if (!p.tryFailure(cause) && logger != null) { Throwable err = p.cause(); if (err == null) { logger.warn("Failed to mark a promise as failure because it has succeeded already: {}", p, cause); } else { logger.warn( "Failed to mark a promise as failure because it has failed already: {}, unnotified cause: {}", p, ThrowableUtil.stackTraceToString(err), cause); } } } }