Back to index...

	/*
	* Copyright (c) 2002, 2014, 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 sun.misc.ThreadGroupUtils;

	import java.lang.ref.Reference;
	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.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 java.security.PrivilegedAction<Void>() {
	public Void run() {
	System.loadLibrary("awt");
	return null;
	}
	});
	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();
	AccessController.doPrivileged(
	(PrivilegedAction<Void>) () -> {
	/* 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 rootTG = ThreadGroupUtils.getRootThreadGroup();
	Thread t = new Thread(rootTG, 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.");
	}
	}
	}

	/*
	* 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.");
	}
	}
	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.");
	} 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;
	}

	}

Back to index...