Tomcat example source code file (FragmentationInterceptor.java)

This example Tomcat source code file (FragmentationInterceptor.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

channelexception, channelmessage, channelmessage, fragcollection, fragcollection, fragkey, fragkey, fragmentationinterceptor, hashmap, interceptorpayload, object, unable, util, xbytebuffer, xbytebuffer

The Tomcat FragmentationInterceptor.java source code

/*
 * 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
 */

package org.apache.catalina.tribes.group.interceptors;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Set;

import org.apache.catalina.tribes.ChannelException;
import org.apache.catalina.tribes.ChannelMessage;
import org.apache.catalina.tribes.Member;
import org.apache.catalina.tribes.group.ChannelInterceptorBase;
import org.apache.catalina.tribes.group.InterceptorPayload;
import org.apache.catalina.tribes.io.XByteBuffer;

/**
 *
 * The fragmentation interceptor splits up large messages into smaller messages and assembles them on the other end.
 * This is very useful when you don't want large messages hogging the sending sockets
 * and smaller messages can make it through.
 * 
 * <br>Configuration Options

 * OrderInteceptor.expire=<milliseconds> - how long do we keep the fragments in memory and wait for the rest to arrivedefault=60,000ms -> 60seconds
 * This setting is useful to avoid OutOfMemoryErrors<br>
 * OrderInteceptor.maxSize=<max message size> - message size in bytes default=1024*100 (around a tenth of a MB)

 * @author Filip Hanik
 * @version 1.0
 */
public class FragmentationInterceptor extends ChannelInterceptorBase {
    private static org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory.getLog( FragmentationInterceptor.class );
    
    protected HashMap fragpieces = new HashMap();
    private int maxSize = 1024*100;
    private long expire = 1000 * 60; //one minute expiration
    protected boolean deepclone = true;


    public void sendMessage(Member[] destination, ChannelMessage msg, InterceptorPayload payload) throws ChannelException {
        int size = msg.getMessage().getLength();
        boolean frag = (size>maxSize) && okToProcess(msg.getOptions());
        if ( frag ) {
            frag(destination, msg, payload);
        } else {
            msg.getMessage().append(frag);
            super.sendMessage(destination, msg, payload);
        }
    }
    
    public void messageReceived(ChannelMessage msg) {
        boolean isFrag = XByteBuffer.toBoolean(msg.getMessage().getBytesDirect(),msg.getMessage().getLength()-1);
        msg.getMessage().trim(1);
        if ( isFrag ) {
            defrag(msg);
        } else {
            super.messageReceived(msg);
        }
    }

    
    public FragCollection getFragCollection(FragKey key, ChannelMessage msg) {
        FragCollection coll = (FragCollection)fragpieces.get(key);
        if ( coll == null ) {
            synchronized (fragpieces) {
                coll = (FragCollection)fragpieces.get(key);
                if ( coll == null ) {
                    coll = new FragCollection(msg);
                    fragpieces.put(key, coll);
                }
            }
        } 
        return coll;
    }
    
    public void removeFragCollection(FragKey key) {
        fragpieces.remove(key);
    }
    
    public void defrag(ChannelMessage msg ) { 
        FragKey key = new FragKey(msg.getUniqueId());
        FragCollection coll = getFragCollection(key,msg);
        coll.addMessage((ChannelMessage)msg.deepclone());

        if ( coll.complete() ) {
            removeFragCollection(key);
            ChannelMessage complete = coll.assemble();
            super.messageReceived(complete);
            
        }
    }

    public void frag(Member[] destination, ChannelMessage msg, InterceptorPayload payload) throws ChannelException {
        int size = msg.getMessage().getLength();

        int count = ((size / maxSize )+(size%maxSize==0?0:1));
        ChannelMessage[] messages = new ChannelMessage[count];
        int remaining = size;
        for ( int i=0; i<count; i++ ) {
            ChannelMessage tmp = (ChannelMessage)msg.clone();
            int offset = (i*maxSize);
            int length = Math.min(remaining,maxSize);
            tmp.getMessage().clear();
            tmp.getMessage().append(msg.getMessage().getBytesDirect(),offset,length);
            //add the msg nr
            //tmp.getMessage().append(XByteBuffer.toBytes(i),0,4);
            tmp.getMessage().append(i);
            //add the total nr of messages
            //tmp.getMessage().append(XByteBuffer.toBytes(count),0,4);
            tmp.getMessage().append(count);
            //add true as the frag flag
            //byte[] flag = XByteBuffer.toBytes(true);
            //tmp.getMessage().append(flag,0,flag.length);
            tmp.getMessage().append(true);
            messages[i] = tmp;
            remaining -= length;
            
        }
        for ( int i=0; i<messages.length; i++ ) {
            super.sendMessage(destination,messages[i],payload);
        }
    }
    
    public void heartbeat() {
        try {
            Set set = fragpieces.keySet(); 
            Object[] keys = set.toArray();
            for ( int i=0; i<keys.length; i++ ) {
                FragKey key = (FragKey)keys[i];
                if ( key != null && key.expired(getExpire()) ) 
                    removeFragCollection(key);
            }
        }catch ( Exception x ) {
            if ( log.isErrorEnabled() ) {
                log.error("Unable to perform heartbeat clean up in the frag interceptor",x);
            }
        }
        super.heartbeat();
    }

    

    public int getMaxSize() {
        return maxSize;
    }

    public long getExpire() {
        return expire;
    }

    public void setMaxSize(int maxSize) {
        this.maxSize = maxSize;
    }

    public void setExpire(long expire) {
        this.expire = expire;
    }

    public static class FragCollection {
        private long received = System.currentTimeMillis();
        private ChannelMessage msg;
        private XByteBuffer[] frags;
        public FragCollection(ChannelMessage msg) {
            //get the total messages
            int count = XByteBuffer.toInt(msg.getMessage().getBytesDirect(),msg.getMessage().getLength()-4);
            frags = new XByteBuffer[count];
            this.msg = msg;
        }
        
        public void addMessage(ChannelMessage msg) {
            //remove the total messages
            msg.getMessage().trim(4);
            //get the msg nr
            int nr = XByteBuffer.toInt(msg.getMessage().getBytesDirect(),msg.getMessage().getLength()-4);
            //remove the msg nr
            msg.getMessage().trim(4);
            frags[nr] = msg.getMessage();
            
        }
        
        public boolean complete() {
            boolean result = true;
            for ( int i=0; (i<frags.length) && (result); i++ ) result = (frags[i] != null);
            return result;
        }
        
        public ChannelMessage assemble() {
            if ( !complete() ) throw new IllegalStateException("Fragments are missing.");
            int buffersize = 0;
            for (int i=0; i<frags.length; i++ ) buffersize += frags[i].getLength();
            XByteBuffer buf = new XByteBuffer(buffersize,false);
            msg.setMessage(buf);
            for ( int i=0; i<frags.length; i++ ) {
                msg.getMessage().append(frags[i].getBytesDirect(),0,frags[i].getLength());
            }
            return msg;
        }
        
        public boolean expired(long expire) {
            return (System.currentTimeMillis()-received)>expire;
        }

        
        
    }
    
    public static class FragKey {
        private byte[] uniqueId;
        private long received = System.currentTimeMillis();
        public FragKey(byte[] id ) {
            this.uniqueId = id;
        }
        public int hashCode() {
            return XByteBuffer.toInt(uniqueId,0);
        }
        
        public boolean equals(Object o ) {
            if ( o instanceof FragKey ) {
            return Arrays.equals(uniqueId,((FragKey)o).uniqueId);
        } else return false;

        }
        
        public boolean expired(long expire) {
            return (System.currentTimeMillis()-received)>expire;
        }

    }
    
}