001/* 002 * The contents of this file are subject to the terms of the Common Development and 003 * Distribution License (the License). You may not use this file except in compliance with the 004 * License. 005 * 006 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the 007 * specific language governing permission and limitations under the License. 008 * 009 * When distributing Covered Software, include this CDDL Header Notice in each file and include 010 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL 011 * Header, with the fields enclosed by brackets [] replaced by your own identifying 012 * information: "Portions Copyright [year] [name of copyright owner]". 013 * 014 * Copyright 2006-2010 Sun Microsystems, Inc. 015 * Portions Copyright 2015 ForgeRock AS. 016 */ 017package org.opends.quicksetup.util; 018 019 020 021/** 022 * This class provides a mechanism for running a task in the background using a 023 * separate thread and providing the caller with notification when it has 024 * completed. 025 * @param <T> type of object returned by this process 026 */ 027public abstract class BackgroundTask<T> 028{ 029 /** 030 * Creates a new thread and begins running the task in the background. When 031 * the task has completed, the {@code backgroundTaskCompleted} method will be 032 * invoked. 033 */ 034 public final void startBackgroundTask() 035 { 036 BackgroundTaskThread<T> taskThread = new BackgroundTaskThread<>(this); 037 taskThread.start(); 038 } 039 040 041 042 /** 043 * Performs all processing associated with the task. 044 * 045 * @return An {@code Object} with information about the processing performed 046 * for this task, or {@code null} if no return value is needed. 047 * 048 * @throws Throwable throwable that will be passed through the method 049 * backgroundTaskCompleted. 050 */ 051 public abstract T processBackgroundTask() throws Throwable; 052 053 054 055 /** 056 * This method will be invoked to indicate that the background task has 057 * completed. If processing completed successfully, then the 058 * {@code Throwable} argument will be {@code null} and the {@code returnValue} 059 * argument will contain the value returned by the 060 * {@code processBackgroundTask} method. If an exception or error was thrown, 061 * then the {@code throwable} argument will not be {@code null}. 062 * 063 * @param returnValue The value returned by the 064 * {@code processBackgroundTask} method when processing 065 * completed, or {@code null} if no value was returned or 066 * an exception was encountered during processing. 067 * @param throwable A {@code Throwable} instance (e.g., an exception) that 068 * was raised during processing, or {@code null} if all 069 * processing completed successfully. 070 */ 071 public abstract void backgroundTaskCompleted(T returnValue, 072 Throwable throwable); 073}