301608 Deregister shutdown hooks

git-svn-id: svn+ssh://dev.eclipse.org/svnroot/rt/org.eclipse.jetty/jetty/trunk@1949 7e9141cc-0065-0410-87d8-b60c137991c4

VERSION.txt

@@ -3,6 +3,7 @@ jetty-7.1.4-SNAPSHOT
  + 292814 Make QoSFilter and DoSFilter JMX manageable
  + 293222 Improve request log to handle/show asynchronous latency
  + 294212 Can not customize session cookie path
+ + 301608 Deregister shutdown hooks
  + 302350 org.eclipse.jetty.server.NCSARequestLog is missing JavaDoc
  + 303661 Startup with jetty.sh-Script failes if JETTY_HOME is not writeable
           for JETTY_USER

jetty-util/src/main/java/org/eclipse/jetty/util/thread/ShutdownThread.java

@@ -35,6 +35,7 @@ public class ShutdownThread extends Thread
 {
     private static final ShutdownThread _thread = new ShutdownThread();
 
+    private boolean _hooked;
     private final List<LifeCycle> _lifeCycles = new CopyOnWriteArrayList<LifeCycle>();
 
     /* ------------------------------------------------------------ */
@@ -44,10 +45,32 @@ public class ShutdownThread extends Thread
      * 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)
         {
@@ -71,18 +94,24 @@ public class ShutdownThread extends 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();
     }
 
     /* ------------------------------------------------------------ */
@@ -101,11 +130,4 @@ public class ShutdownThread extends Thread
             }
         }
     }
-
-    /* ------------------------------------------------------------ */
-    protected Object readResolve()
-        throws ObjectStreamException
-    {
-        return _thread;
-    }
 }