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HSQLDB example source code file (HsqlTaskQueue.java)
The HSQLDB HsqlTaskQueue.java source code/* Copyright (c) 2001-2008, The HSQL Development Group * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of the HSQL Development Group nor the names of its * contributors may be used to endorse or promote products derived from this * software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG, * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package org.hsqldb.lib; /** * Provides very simple queued execution of Runnable objects in a background * thread. The underlying queue is an HsqlDeque instance, an array-based * circular queue implementation with automatic capacity expansion. * * @author boucherb@users * @version 1.7.2 * @since 1.7.2 */ public class HsqlTaskQueue { /** The thread used to process commands */ protected Thread taskRunnerThread; /** Special queue element to signal termination */ protected static final Runnable SHUTDOWNTASK = new Runnable() { public void run() {} }; /** * true if thread should shut down after processing current task. * * Once set true, stays true forever */ protected volatile boolean isShutdown; public synchronized Thread getTaskRunnerThread() { return taskRunnerThread; } protected synchronized void clearThread() { taskRunnerThread = null; } protected final HsqlDeque queue = new HsqlDeque(); protected class TaskRunner implements Runnable { public void run() { Runnable task; try { while (!isShutdown) { synchronized (queue) { task = (Runnable) queue.getFirst(); } if (task == SHUTDOWNTASK) { isShutdown = true; synchronized (queue) { queue.clear(); } break; } else if (task != null) { task.run(); task = null; } else { break; } } } finally { clearThread(); } } } protected final TaskRunner taskRunner = new TaskRunner(); public HsqlTaskQueue() {} public boolean isShutdown() { return isShutdown; } public synchronized void restart() { if (taskRunnerThread == null &&!isShutdown) { taskRunnerThread = new Thread(taskRunner); taskRunnerThread.start(); } } public void execute(Runnable command) throws RuntimeException { if (!isShutdown) { synchronized (queue) { queue.addLast(command); } restart(); } } public synchronized void shutdownAfterQueued() { if (!isShutdown) { synchronized (queue) { queue.addLast(SHUTDOWNTASK); } } } public synchronized void shutdownAfterCurrent() { isShutdown = true; synchronized (queue) { queue.clear(); queue.addLast(SHUTDOWNTASK); } } public synchronized void shutdownImmediately() { isShutdown = true; if (taskRunnerThread != null) { taskRunnerThread.interrupt(); } synchronized (queue) { queue.clear(); queue.addLast(SHUTDOWNTASK); } } } Other HSQLDB examples (source code examples)Here is a short list of links related to this HSQLDB HsqlTaskQueue.java source code file: |
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