/*
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* The contents of this file are subject to the terms of the Common Development and
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* Distribution License (the License). You may not use this file except in compliance with the
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* License.
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*
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* You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
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* specific language governing permission and limitations under the License.
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*
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* When distributing Covered Software, include this CDDL Header Notice in each file and include
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* the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
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* Header, with the fields enclosed by brackets [] replaced by your own identifying
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* information: "Portions Copyright [year] [name of copyright owner]".
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*
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* Copyright 2008 Sun Microsystems, Inc.
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* Portions Copyright 2015 ForgeRock AS.
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*/
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package org.opends.guitools.controlpanel.util;
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/**
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* This class provides a mechanism for running a task in the background using a
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* separate thread and providing the caller with notification when it has
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* completed.
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* @param <T> type of object returned by this process
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*/
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public abstract class BackgroundTask<T>
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{
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private BackgroundTaskThread<T> taskThread;
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private boolean interrupted;
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/**
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* Creates a new thread and begins running the task in the background. When
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* the task has completed, the {@code backgroundTaskCompleted} method will be
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* invoked.
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*/
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public final void startBackgroundTask()
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{
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interrupted = false;
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taskThread = new BackgroundTaskThread<>(this);
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taskThread.start();
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}
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/** Interrupts the thread that is running background. */
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public final void interrupt()
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{
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interrupted = true;
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if (taskThread != null)
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{
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taskThread.interrupt();
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}
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}
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/**
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* Returns <CODE>true</CODE> if the thread running in the background is
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* interrupted and <CODE>false</CODE> otherwise.
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* @return <CODE>true</CODE> if the thread running in the background is
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* interrupted and <CODE>false</CODE> otherwise.
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*/
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public boolean isInterrupted()
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{
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return interrupted;
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}
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/**
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* Performs all processing associated with the task.
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*
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* @return An {@code Object} with information about the processing performed
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* for this task, or {@code null} if no return value is needed.
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*
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* @throws Throwable throwable that will be passed through the method
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* backgroundTaskCompleted.
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*/
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public abstract T processBackgroundTask() throws Throwable;
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/**
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* This method will be invoked to indicate that the background task has
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* completed. If processing completed successfully, then the
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* {@code Throwable} argument will be {@code null} and the {@code returnValue}
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* argument will contain the value returned by the
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* {@code processBackgroundTask} method. If an exception or error was thrown,
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* then the {@code throwable} argument will not be {@code null}.
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*
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* @param returnValue The value returned by the
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* {@code processBackgroundTask} method when processing
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* completed, or {@code null} if no value was returned or
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* an exception was encountered during processing.
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* @param throwable A {@code Throwable} instance (e.g., an exception) that
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* was raised during processing, or {@code null} if all
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* processing completed successfully.
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*/
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public abstract void backgroundTaskCompleted(T returnValue,
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Throwable throwable);
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}
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