INTEGRATION: CWS mtg1 (1.1.2); FILE ADDED

2005/11/16 14:39:56 sb 1.1.2.1: #i57753# Avoid long-running finalize methods.

jurt/com/sun/star/lib/util/AsynchronousFinalizer.java

+/*************************************************************************
+ *
+ *  OpenOffice.org - a multi-platform office productivity suite
+ *
+ *  $RCSfile: AsynchronousFinalizer.java,v $
+ *
+ *  $Revision: 1.2 $
+ *
+ *  last change: $Author: rt $ $Date: 2006-01-09 09:48:43 $
+ *
+ *  The Contents of this file are made available subject to
+ *  the terms of GNU Lesser General Public License Version 2.1.
+ *
+ *
+ *    GNU Lesser General Public License Version 2.1
+ *    =============================================
+ *    Copyright 2005 by Sun Microsystems, Inc.
+ *    901 San Antonio Road, Palo Alto, CA 94303, USA
+ *
+ *    This library is free software; you can redistribute it and/or
+ *    modify it under the terms of the GNU Lesser General Public
+ *    License version 2.1, as published by the Free Software Foundation.
+ *
+ *    This library is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *    Lesser General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Lesser General Public
+ *    License along with this library; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ *    MA  02111-1307  USA
+ *
+ ************************************************************************/
+
+package com.sun.star.lib.util;
+
+import java.util.LinkedList;
+
+/**
+   Helper class to asynchronously execute finalize methods.
+
+   Current JVMs seem not to be robust against long-running finalize methods, in
+   that such long-running finalize methods may lead to OutOfMemoryErrors.  This
+   class mitigates the problem by asynchronously shifting the bodies of
+   potentially long-running finalize methods into an extra thread.  Classes that
+   make use of this in their finalize methods are the proxies used in the
+   intra-process JNI UNO bridge and the inter-process Java URP UNO bridge (where
+   in both cases finalizers lead to synchronous UNO release calls).
+
+   If JVMs are getting more mature and should no longer have problems with
+   long-running finalize mehtods, this class could be removed again.
+*/
+public final class AsynchronousFinalizer {
+    /**
+       Add a job to be executed asynchronously.
+
+       The run method of the given job is called exactly once.  If it terminates
+       abnormally by throwing any Throwable, that is ignored.
+
+       @param job represents the body of some finalize method; must not be null.
+    */
+    public static void add(Job job) {
+        synchronized (queue) {
+            boolean first = queue.isEmpty();
+            queue.add(job);
+            if (first) {
+                queue.notify();
+            }
+        }
+    }
+
+    /**
+       An interface to represent bodies of finalize methods.
+
+       Similar to Runnable, except that the run method may throw any Throwable
+       (which is effectively ignored by AsynchronousFinalizer.add, similar to
+       any Throwables raised by finalize being ignored).
+    */
+    public interface Job {
+        void run() throws Throwable;
+    }
+
+    private static final LinkedList queue = new LinkedList();
+
+    static {
+        Thread t = new Thread() {
+                public void run() {
+                    for (;;) {
+                        Job j;
+                        synchronized (queue) {
+                            while (queue.isEmpty()) {
+                                try {
+                                    queue.wait();
+                                } catch (InterruptedException e) {}
+                            }
+                            j = (Job) queue.remove(0);
+                        }
+                        try {
+                            j.run();
+                        } catch (Throwable e) {}
+                    }
+                }
+            };
+        t.setDaemon(true);
+        t.start();
+    }
+
+    private AsynchronousFinalizer() {}
+}