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JSF components and utilities that can be used with any JSF implementation. This library is based on the JSF1.1 version of Tomahawk, but with minor source code and build changes to take advantage of JSF1.2 features. A JSF1.2 implementation is required to use this version of the Tomahawk library.
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.myfaces.component.html.util;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.myfaces.component.html.util.StreamingAddResource.StreamablePositionedInfo;

public class StreamingThreadManager
{
    public final static String KEY = "org.apache.myfaces.component.html.util.StreamingThreadManager";
    
    /**
     * central place where all request store their "to be added" stylesheets
     */
    private final Map headerInfos = new HashMap();
    
    private Thread cleanupThread = null;
    
    private CleanupThread cleanupThreadObject = null;
    
    /**
     * request counter
     */
    private volatile long REQUEST_ID_COUNTER = 0;

    public StreamingThreadManager()
    {
    }
    
    public void init()
    {
        if (cleanupThread == null)
        {
            cleanupThreadObject = new CleanupThread();
            cleanupThread = new Thread(cleanupThreadObject, "StreamingAddResource.CleanupThread");
            cleanupThread.setDaemon(true);
            cleanupThread.start();
        }
    }
    
    public void destroy()
    {
        if (cleanupThread != null)
        {
            cleanupThreadObject.done();
            cleanupThread.interrupt();
            cleanupThread = null;
            synchronized (headerInfos)
            {
                headerInfos.clear();
            }
        }
    }
    
    public HeaderInfoEntry getHeaderInfo(Long requestId)
    {
        synchronized (headerInfos)
        {
            return (HeaderInfoEntry) headerInfos.get(requestId);
        }
    }
    
    public Long putNewHeaderInfoEntry()
    {
        Long requestId = null;
        synchronized(this)
        {
            REQUEST_ID_COUNTER++;
            requestId = new Long(REQUEST_ID_COUNTER);
        }
        HeaderInfoEntry headerInfoEntry = new HeaderInfoEntry();
        synchronized (headerInfos)
        {
            headerInfos.put(requestId, headerInfoEntry);
        }
        return requestId;
    }

    public void removeHeaderInfo(Long requestId)
    {
        synchronized (headerInfos)
        {
            headerInfos.remove(requestId);
        }
    }
    
    public static class HeaderInfoEntry
    {
        private final long destroyTime = System.currentTimeMillis() + (1000 * 60); // one minute;
        private final List addedInfos = new ArrayList(10);
        private volatile boolean requestDone = false;

        protected HeaderInfoEntry()
        {
        }

        protected boolean isDestroyable(long now)
        {
            return destroyTime < now;
        }

        protected void addInfo(StreamablePositionedInfo positionedInfo)
        {
            synchronized (addedInfos)
            {
                addedInfos.add(positionedInfo);
                addedInfos.notifyAll();
            }
        }

        protected StreamablePositionedInfo fetchInfo() throws InterruptedException
        {
            synchronized (addedInfos)
            {
                while (addedInfos.size() < 1 && !requestDone)
                {
                    addedInfos.wait(100);
                }
                if (addedInfos.size() < 1)
                {
                    // request done
                    return null;
                }

                return (StreamablePositionedInfo) addedInfos.remove(0);
            }
        }

        protected void setRequestDone()
        {
            requestDone = true;
        }
    }
    
    private class CleanupThread implements Runnable
    {
        // how many entries should be removed per run
        private final static int CHECKS_PER_RUN = 10;

        // but never reach this maximum
        private final static int CACHE_LIMIT = 1000;
        
        private boolean threadDone = false;

        public void run()
        {
            while (!Thread.interrupted() && !threadDone)
            {
                checkMap();

                try
                {
                    Thread.sleep(1000 * 30); // check every 30 sek
                }
                catch (InterruptedException e)
                {
                    // ignore
                }
            }
        }
        
        public void done() {
            threadDone = true;
        }

        private void checkMap()
        {
            synchronized (headerInfos)
            {
                long now = System.currentTimeMillis();

                int checkNo = 0;
                Iterator iterEntries = headerInfos.entrySet().iterator();
                while (iterEntries.hasNext() && !Thread.currentThread().isInterrupted())
                {
                    checkNo++;
                    if (headerInfos.size() < CACHE_LIMIT && checkNo > CHECKS_PER_RUN)
                    {
                        return;
                    }
                    Map.Entry entry = (Map.Entry) iterEntries.next();
                    HeaderInfoEntry headerInfoEntry = (HeaderInfoEntry) entry.getValue();
                    if (headerInfoEntry.isDestroyable(now))
                    {
                        iterEntries.remove();
                    }
                }
            }
        }
    }
}