ojluni/src/main/java/sun/awt/image/ImageFetcher.java - platform/libcore - Git at Google

 /*
  * 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;
         }
     }
 }
	/*
	* 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;
	}
	}
	}