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/* * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package sun.java2d; import java.lang.ref.Reference;import java.lang.ref.ReferenceQueue;import java.lang.ref.PhantomReference;import java.lang.ref.WeakReference;import java.util.ArrayList;import java.util.Hashtable; /** * This class is used for registering and disposing the native * data associated with java objects. * * The object can register itself by calling one of the addRecord * methods and providing either the pointer to the native disposal * method or a descendant of the DisposerRecord class with overridden * dispose() method. * * When the object becomes unreachable, the dispose() method * of the associated DisposerRecord object will be called. * * @see DisposerRecord */public class Disposer implements Runnable {    private static final ReferenceQueue queue = new ReferenceQueue();    private static final Hashtable records = new Hashtable();     private static Disposer disposerInstance;    public static final int WEAK = 0;    public static final int PHANTOM = 1;    public static int refType = PHANTOM;     static {        java.security.AccessController.doPrivileged(            new sun.security.action.LoadLibraryAction("awt"));        initIDs();        String type = (String) java.security.AccessController.doPrivileged(                new sun.security.action.GetPropertyAction("sun.java2d.reftype"));        if (type != null) {            if (type.equals("weak")) {                refType = WEAK;                System.err.println("Using WEAK refs");            } else {                refType = PHANTOM;                System.err.println("Using PHANTOM refs");            }        }        disposerInstance = new Disposer();        java.security.AccessController.doPrivileged(            new java.security.PrivilegedAction() {                public Object run() {                    /* The thread must be a member of a thread group                     * which will not get GCed before VM exit.                     * Make its parent the top-level thread group.                     */                    ThreadGroup tg = Thread.currentThread().getThreadGroup();                    for (ThreadGroup tgn = tg;                         tgn != null;                         tg = tgn, tgn = tg.getParent());                    Thread t =                        new Thread(tg, disposerInstance, "Java2D Disposer");                    t.setContextClassLoader(null);                    t.setDaemon(true);                    t.setPriority(Thread.MAX_PRIORITY);                    t.start();                    return null;                }            }        );    }     /**     * Registers the object and the native data for later disposal.     * @param target Object to be registered     * @param disposeMethod pointer to the native disposal method     * @param pData pointer to the data to be passed to the     *              native disposal method     */    public static void addRecord(Object target,                                 long disposeMethod, long pData)    {        disposerInstance.add(target,                             new DefaultDisposerRecord(disposeMethod, pData));    }     /**     * Registers the object and the native data for later disposal.     * @param target Object to be registered     * @param rec the associated DisposerRecord object     * @see DisposerRecord     */    public static void addRecord(Object target, DisposerRecord rec) {        disposerInstance.add(target, rec);    }     /**     * Performs the actual registration of the target object to be disposed.     * @param target Object to be registered, or if target is an instance     *               of DisposerTarget, its associated disposer referent     *               will be the Object that is registered     * @param rec the associated DisposerRecord object     * @see DisposerRecord     */    synchronized void add(Object target, DisposerRecord rec) {        if (target instanceof DisposerTarget) {            target = ((DisposerTarget)target).getDisposerReferent();        }        java.lang.ref.Reference ref;        if (refType == PHANTOM) {            ref = new PhantomReference(target, queue);        } else {            ref = new WeakReference(target, queue);        }        records.put(ref, rec);    }     public void run() {        while (true) {            try {                Object obj = queue.remove();                ((Reference)obj).clear();                DisposerRecord rec = (DisposerRecord)records.remove(obj);                rec.dispose();                obj = null;                rec = null;                clearDeferredRecords();            } catch (Exception e) {                System.out.println("Exception while removing reference: " + e);                e.printStackTrace();            }        }    }     /*     * This is a marker interface that, if implemented, means it     * doesn't acquire any special locks, and is safe to     * be disposed in the poll loop on whatever thread     * which happens to be the Toolkit thread, is in use.     */    public static interface PollDisposable {    };     private static ArrayList<DisposerRecord> deferredRecords = null;     private static void clearDeferredRecords() {        if (deferredRecords == null || deferredRecords.isEmpty()) {            return;        }        for (int i=0;i<deferredRecords.size(); i++) {            try {                DisposerRecord rec = deferredRecords.get(i);                rec.dispose();            } catch (Exception e) {                System.out.println("Exception while disposing deferred rec.");                e.printStackTrace();            }        }        deferredRecords.clear();    }     /*     * Set to indicate the queue is presently being polled.     */    public static volatile boolean pollingQueue = false;     /*     * The pollRemove() method is called back from a dispose method     * that is running on the toolkit thread and wants to     * dispose any pending refs that are safe to be disposed     * on that thread.     */    public static void pollRemove() {         /* This should never be called recursively, so this check         * is just a safeguard against the unexpected.         */        if (pollingQueue) {            return;        }        Object obj;        pollingQueue = true;        int freed = 0;        int deferred = 0;        try {            while ((obj = queue.poll()) != null                   && freed < 10000 && deferred < 100) {                freed++;                ((Reference)obj).clear();                DisposerRecord rec = (DisposerRecord)records.remove(obj);                if (rec instanceof PollDisposable) {                    rec.dispose();                    obj = null;                    rec = null;                } else {                    if (rec == null) { // shouldn't happen, but just in case.                        continue;                    }                    deferred++;                    if (deferredRecords == null) {                      deferredRecords = new ArrayList<DisposerRecord>(5);                    }                    deferredRecords.add(rec);                }            }        } catch (Exception e) {            System.out.println("Exception while removing reference: " + e);            e.printStackTrace();        } finally {            pollingQueue = false;        }    }     private static native void initIDs();     /*     * This was added for use by the 2D font implementation to avoid creation     * of an additional disposer thread.     * WARNING: this thread class monitors a specific queue, so a reference     * added here must have been created with this queue. Failure to do     * so will clutter the records hashmap and no one will be cleaning up     * the reference queue.     */    public static void addReference(Reference ref, DisposerRecord rec) {        records.put(ref, rec);    }     public static void addObjectRecord(Object obj, DisposerRecord rec) {        records.put(new WeakReference(obj, queue) , rec);    }     /* This is intended for use in conjunction with addReference(..)     */    public static ReferenceQueue getQueue() {        return queue;    } }