Importing upstream Jetty jetty-9.2.1.v20140609

[gigi.git] / lib / jetty / org / eclipse / jetty / util / thread / ShutdownThread.java

diff --git a/lib/jetty/org/eclipse/jetty/util/thread/ShutdownThread.java b/lib/jetty/org/eclipse/jetty/util/thread/ShutdownThread.java
new file mode 100644 (file)
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+++ b/lib/jetty/org/eclipse/jetty/util/thread/ShutdownThread.java
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+//
+//  ========================================================================
+//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.util.thread;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import org.eclipse.jetty.util.component.Destroyable;
+import org.eclipse.jetty.util.component.LifeCycle;
+import org.eclipse.jetty.util.log.Log;
+import org.eclipse.jetty.util.log.Logger;
+
+
+/* ------------------------------------------------------------ */
+/**
+ * ShutdownThread is a shutdown hook thread implemented as 
+ * singleton that maintains a list of lifecycle instances
+ * that are registered with it and provides ability to stop
+ * these lifecycles upon shutdown of the Java Virtual Machine 
+ */
+public class ShutdownThread extends Thread
+{
+    private static final Logger LOG = Log.getLogger(ShutdownThread.class);
+    private static final ShutdownThread _thread = new ShutdownThread();
+
+    private boolean _hooked;
+    private final List<LifeCycle> _lifeCycles = new CopyOnWriteArrayList<LifeCycle>();
+
+    /* ------------------------------------------------------------ */
+    /**
+     * Default constructor for the singleton
+     * 
+     * Registers the instance as shutdown hook with the Java Runtime
+     */
+    private ShutdownThread()
+    {
+    }
+    
+    /* ------------------------------------------------------------ */
+    private synchronized void hook()
+    {
+        try
+        {
+            if (!_hooked)
+                Runtime.getRuntime().addShutdownHook(this);
+            _hooked=true;
+        }
+        catch(Exception e)
+        {
+            LOG.ignore(e);
+            LOG.info("shutdown already commenced");
+        }
+    }
+    
+    /* ------------------------------------------------------------ */
+    private synchronized void unhook()
+    {
+        try
+        {
+            _hooked=false;
+            Runtime.getRuntime().removeShutdownHook(this);
+        }
+        catch(Exception e)
+        {
+            LOG.ignore(e);
+            LOG.debug("shutdown already commenced");
+        }
+    }
+    
+    /* ------------------------------------------------------------ */
+    /**
+     * Returns the instance of the singleton
+     * 
+     * @return the singleton instance of the {@link ShutdownThread}
+     */
+    public static ShutdownThread getInstance()
+    {
+        return _thread;
+    }
+
+    /* ------------------------------------------------------------ */
+    public static synchronized void register(LifeCycle... lifeCycles)
+    {
+        _thread._lifeCycles.addAll(Arrays.asList(lifeCycles));
+        if (_thread._lifeCycles.size()>0)
+            _thread.hook();
+    }
+
+    /* ------------------------------------------------------------ */
+    public static synchronized void register(int index, LifeCycle... lifeCycles)
+    {
+        _thread._lifeCycles.addAll(index,Arrays.asList(lifeCycles));
+        if (_thread._lifeCycles.size()>0)
+            _thread.hook();
+    }
+    
+    /* ------------------------------------------------------------ */
+    public static synchronized void deregister(LifeCycle lifeCycle)
+    {
+        _thread._lifeCycles.remove(lifeCycle);
+        if (_thread._lifeCycles.size()==0)
+            _thread.unhook();
+    }
+
+    /* ------------------------------------------------------------ */
+    @Override
+    public void run()
+    {
+        for (LifeCycle lifeCycle : _thread._lifeCycles)
+        {
+            try
+            {
+                if (lifeCycle.isStarted())
+                {
+                    lifeCycle.stop();
+                    LOG.debug("Stopped {}",lifeCycle);
+                }
+                
+                if (lifeCycle instanceof Destroyable)
+                {
+                    ((Destroyable)lifeCycle).destroy();
+                    LOG.debug("Destroyed {}",lifeCycle);
+                }
+            }
+            catch (Exception ex)
+            {
+                LOG.debug(ex);
+            }
+        }
+    }
+}