Disposer.java

/*
 * This file is modified by Ivan Maidanski <ivmai@ivmaisoft.com>
 * Project name: JCGO-SUNAWT (http://www.ivmaisoft.com/jcgo/)
 */

/*
 * @(#)Disposer.java    1.4 03/03/19
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package sun.java2d;

import java.lang.ref.ReferenceQueue;
import java.lang.ref.PhantomReference;
import java.lang.ref.WeakReference;

import java.security.AccessController;
import java.security.PrivilegedAction;

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();

    public static final int WEAK = 0;
    public static final int PHANTOM = 1;
    public static int refType = PHANTOM;

    static {
        AccessController.doPrivileged(
                new sun.security.action.LoadLibraryAction("awt"));
        initIDs();
        String type = (String) AccessController.doPrivileged(
                new sun.security.action.GetPropertyAction("sun.java2d.reftype"));
        if (type != null) {
            if (type.equals("weak")) {
                refType = WEAK;
                System.out.println("Disposer: using WEAK refs");
            } else {
                System.out.println("Disposer: using PHANTOM refs");
            }
        }
    }

    private static final Disposer disposerInstance = new Disposer();

    static {
        AccessController.doPrivileged(new PrivilegedAction() {

            public Object run() {
                ThreadGroup tg = Thread.currentThread().getThreadGroup();
                for (ThreadGroup tg2 = tg; tg2 != null; tg2 = tg.getParent())
                    tg = tg2;

                Thread t = new Thread(tg, disposerInstance, "Java2D Disposer");
                t.setDaemon(true);
                t.setPriority(Thread.MAX_PRIORITY);
                t.start();
                return null;
            }
        });
    }

    /**
     * Registers the object and the native data for later disposal.
     * @param obj 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(DisposerTarget target,
                                 long disposeMethod, long pData) {
        disposerInstance.add(target,
                             new DefaultDisposerRecord(disposeMethod, pData));
    }

    /**
     * Registers the object and the native data for later disposal.
     * @param obj Object to be registered
     * @param rec The assosicated DisposerRecord class
     * @see DisposerRecord
     */
    public static void addRecord(DisposerTarget target, DisposerRecord rec) {
        disposerInstance.add(target, rec);
    }

    public static void addRecord(Object target, DisposerRecord rec) {
        disposerInstance.add(target, rec);
    }

    synchronized void add(Object target, DisposerRecord rec) {
        DisposerTarget disposerTarget = null;
        if (target instanceof DisposerTarget) {
            disposerTarget = (DisposerTarget)target;
            target = disposerTarget.getDisposerReferent();
        }

        java.lang.ref.Reference ref;
        if (refType == PHANTOM) {
            ref = new PhantomReference(target, queue);
        } else {
            ref = new WeakReference(target, queue);
        }
        records.put(ref, rec);

        /* store the disposer record  for later use */
        if (disposerTarget != null) {
            disposerTarget.setDisposerRecord(rec);
        }
    }

    public void run() {
        while (true) {
            try {
                java.lang.ref.Reference obj = queue.remove();
                DisposerRecord rec = (DisposerRecord)records.remove(obj);
                rec.dispose();
                obj = null;
                rec = null;
            } catch (Exception e) {
                System.out.println("Exception while removing reference: " + e);
                e.printStackTrace();
            }
        }
    }

    private static native void initIDs();
}