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	/*
	* Copyright (c) 1995, 2011, 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.awt.image;

	import java.util.Vector;
	import sun.awt.AppContext;

	/**
	* An ImageFetcher is a thread used to fetch ImageFetchable objects.
	* Once an ImageFetchable object has been fetched, the ImageFetcher
	* thread may also be used to animate it if necessary, via the
	* startingAnimation() / stoppingAnimation() methods.
	*
	* There can be up to FetcherInfo.MAX_NUM_FETCHERS_PER_APPCONTEXT
	* ImageFetcher threads for each AppContext. A per-AppContext queue
	* of ImageFetchables is used to track objects to fetch.
	*
	* @author Jim Graham
	* @author Fred Ecks
	*/
	class ImageFetcher extends Thread {
	static final int HIGH_PRIORITY = 8;
	static final int LOW_PRIORITY = 3;
	static final int ANIM_PRIORITY = 2;

	static final int TIMEOUT = 5000; // Time in milliseconds to wait for an
	// ImageFetchable to be added to the
	// queue before an ImageFetcher dies

	/**
	* Constructor for ImageFetcher -- only called by add() below.
	*/
	private ImageFetcher(ThreadGroup threadGroup, int index) {
	super(threadGroup, "Image Fetcher " + index);
	setDaemon(true);
	}

	/**
	* Adds an ImageFetchable to the queue of items to fetch. Instantiates
	* a new ImageFetcher if it's reasonable to do so.
	* If there is no available fetcher to process an ImageFetchable, then
	* reports failure to caller.
	*/
	public static boolean add(ImageFetchable src) {
	final FetcherInfo info = FetcherInfo.getFetcherInfo();
	synchronized(info.waitList) {
	if (!info.waitList.contains(src)) {
	info.waitList.addElement(src);
	if (info.numWaiting == 0 &&
	info.numFetchers < info.fetchers.length) {
	createFetchers(info);
	}
	/* Creation of new fetcher may fail due to high vm load
	* or some other reason.
	* If there is already exist, but busy, fetcher, we leave
	* the src in queue (it will be handled by existing
	* fetcher later).
	* Otherwise, we report failure: there is no fetcher
	* to handle the src.
	*/
	if (info.numFetchers > 0) {
	info.waitList.notify();
	} else {
	info.waitList.removeElement(src);
	return false;
	}
	}
	}
	return true;
	}

	/**
	* Removes an ImageFetchable from the queue of items to fetch.
	*/
	public static void remove(ImageFetchable src) {
	final FetcherInfo info = FetcherInfo.getFetcherInfo();
	synchronized(info.waitList) {
	if (info.waitList.contains(src)) {
	info.waitList.removeElement(src);
	}
	}
	}

	/**
	* Checks to see if the given thread is one of the ImageFetchers.
	*/
	public static boolean isFetcher(Thread t) {
	final FetcherInfo info = FetcherInfo.getFetcherInfo();
	synchronized(info.waitList) {
	for (int i = 0; i < info.fetchers.length; i++) {
	if (info.fetchers[i] == t) {
	return true;
	}
	}
	}
	return false;
	}

	/**
	* Checks to see if the current thread is one of the ImageFetchers.
	*/
	public static boolean amFetcher() {
	return isFetcher(Thread.currentThread());
	}

	/**
	* Returns the next ImageFetchable to be processed. If TIMEOUT
	* elapses in the mean time, or if the ImageFetcher is interrupted,
	* null is returned.
	*/
	private static ImageFetchable nextImage() {
	final FetcherInfo info = FetcherInfo.getFetcherInfo();
	synchronized(info.waitList) {
	ImageFetchable src = null;
	long end = System.currentTimeMillis() + TIMEOUT;
	while (src == null) {
	while (info.waitList.size() == 0) {
	long now = System.currentTimeMillis();
	if (now >= end) {
	return null;
	}
	try {
	info.numWaiting++;
	info.waitList.wait(end - now);
	} catch (InterruptedException e) {
	// A normal occurrence as an AppContext is disposed
	return null;
	} finally {
	info.numWaiting--;
	}
	}
	src = (ImageFetchable) info.waitList.elementAt(0);
	info.waitList.removeElement(src);
	}
	return src;
	}
	}

	/**
	* The main run() method of an ImageFetcher Thread. Calls fetchloop()
	* to do the work, then removes itself from the array of ImageFetchers.
	*/
	public void run() {
	final FetcherInfo info = FetcherInfo.getFetcherInfo();
	try {
	fetchloop();
	} catch (Exception e) {
	e.printStackTrace();
	} finally {
	synchronized(info.waitList) {
	Thread me = Thread.currentThread();
	for (int i = 0; i < info.fetchers.length; i++) {
	if (info.fetchers[i] == me) {
	info.fetchers[i] = null;
	info.numFetchers--;
	}
	}
	}
	}
	}

	/**
	* The main ImageFetcher loop. Repeatedly calls nextImage(), and
	* fetches the returned ImageFetchable objects until nextImage()
	* returns null.
	*/
	private void fetchloop() {
	Thread me = Thread.currentThread();
	while (isFetcher(me)) {
	// we're ignoring the return value and just clearing
	// the interrupted flag, instead of bailing out if
	// the fetcher was interrupted, as we used to,
	// because there may be other images waiting
	// to be fetched (see 4789067)
	me.interrupted();
	me.setPriority(HIGH_PRIORITY);
	ImageFetchable src = nextImage();
	if (src == null) {
	return;
	}
	try {
	src.doFetch();
	} catch (Exception e) {
	System.err.println("Uncaught error fetching image:");
	e.printStackTrace();
	}
	stoppingAnimation(me);
	}
	}


	/**
	* Recycles this ImageFetcher thread as an image animator thread.
	* Removes this ImageFetcher from the array of ImageFetchers, and
	* resets the thread name to "ImageAnimator".
	*/
	static void startingAnimation() {
	final FetcherInfo info = FetcherInfo.getFetcherInfo();
	Thread me = Thread.currentThread();
	synchronized(info.waitList) {
	for (int i = 0; i < info.fetchers.length; i++) {
	if (info.fetchers[i] == me) {
	info.fetchers[i] = null;
	info.numFetchers--;
	me.setName("Image Animator " + i);
	if(info.waitList.size() > info.numWaiting) {
	createFetchers(info);
	}
	return;
	}
	}
	}
	me.setPriority(ANIM_PRIORITY);
	me.setName("Image Animator");
	}

	/**
	* Returns this image animator thread back to service as an ImageFetcher
	* if possible. Puts it back into the array of ImageFetchers and sets
	* the thread name back to "Image Fetcher". If there are already the
	* maximum number of ImageFetchers, this method simply returns, and
	* fetchloop() will drop out when it sees that this thread isn't one of
	* the ImageFetchers, and this thread will die.
	*/
	private static void stoppingAnimation(Thread me) {
	final FetcherInfo info = FetcherInfo.getFetcherInfo();
	synchronized(info.waitList) {
	int index = -1;
	for (int i = 0; i < info.fetchers.length; i++) {
	if (info.fetchers[i] == me) {
	return;
	}
	if (info.fetchers[i] == null) {
	index = i;
	}
	}
	if (index >= 0) {
	info.fetchers[index] = me;
	info.numFetchers++;
	me.setName("Image Fetcher " + index);
	return;
	}
	}
	}

	/**
	* Create and start ImageFetcher threads in the appropriate ThreadGroup.
	*/
	private static void createFetchers(final FetcherInfo info) {
	// We need to instantiate a new ImageFetcher thread.
	// First, figure out which ThreadGroup we'll put the
	// new ImageFetcher into
	final AppContext appContext = AppContext.getAppContext();
	ThreadGroup threadGroup = appContext.getThreadGroup();
	ThreadGroup fetcherThreadGroup;
	try {
	if (threadGroup.getParent() != null) {
	// threadGroup is not the root, so we proceed
	fetcherThreadGroup = threadGroup;
	} else {
	// threadGroup is the root ("system") ThreadGroup.
	// We instead want to use its child: the "main"
	// ThreadGroup. Thus, we start with the current
	// ThreadGroup, and go up the tree until
	// threadGroup.getParent().getParent() == null.
	threadGroup = Thread.currentThread().getThreadGroup();
	ThreadGroup parent = threadGroup.getParent();
	while ((parent != null)
	&& (parent.getParent() != null)) {
	threadGroup = parent;
	parent = threadGroup.getParent();
	}
	fetcherThreadGroup = threadGroup;
	}
	} catch (SecurityException e) {
	// Not allowed access to parent ThreadGroup -- just use
	// the AppContext's ThreadGroup
	fetcherThreadGroup = appContext.getThreadGroup();
	}
	final ThreadGroup fetcherGroup = fetcherThreadGroup;

	java.security.AccessController.doPrivileged(
	new java.security.PrivilegedAction() {
	public Object run() {
	for (int i = 0; i < info.fetchers.length; i++) {
	if (info.fetchers[i] == null) {
	ImageFetcher f = new ImageFetcher(
	fetcherGroup, i);
	try {
	f.start();
	info.fetchers[i] = f;
	info.numFetchers++;
	break;
	} catch (Error e) {
	}
	}
	}
	return null;
	}
	});
	return;
	}

	}

	/**
	* The FetcherInfo class encapsulates the per-AppContext ImageFetcher
	* information. This includes the array of ImageFetchers, as well as
	* the queue of ImageFetchable objects.
	*/
	class FetcherInfo {
	static final int MAX_NUM_FETCHERS_PER_APPCONTEXT = 4;

	Thread[] fetchers;
	int numFetchers;
	int numWaiting;
	Vector waitList;

	private FetcherInfo() {
	fetchers = new Thread[MAX_NUM_FETCHERS_PER_APPCONTEXT];
	numFetchers = 0;
	numWaiting = 0;
	waitList = new Vector();
	}

	/* The key to put()/get() the FetcherInfo into/from the AppContext. */
	private static final Object FETCHER_INFO_KEY =
	new StringBuffer("FetcherInfo");

	static FetcherInfo getFetcherInfo() {
	AppContext appContext = AppContext.getAppContext();
	synchronized(appContext) {
	FetcherInfo info = (FetcherInfo)appContext.get(FETCHER_INFO_KEY);
	if (info == null) {
	info = new FetcherInfo();
	appContext.put(FETCHER_INFO_KEY, info);
	}
	return info;
	}
	}
	}

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