Tomcat example source code file (XByteBuffer.java)

This example Tomcat source code file (XByteBuffer.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

arrayindexoutofboundsexception, channeldata, classcastexception, classcastexception, classnotfoundexception, end_data, io, ioexception, ioexception, nio, objectoutputstream, serializable, serializable, start_data, xbytebuffer, xbytebuffer

The Tomcat XByteBuffer.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
 * limitations under the License.
 */

package org.apache.catalina.tribes.io;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.nio.ByteBuffer;

/**
 * The XByteBuffer provides a dual functionality.
 * One, it stores message bytes and automatically extends the byte buffer if needed.<BR>
 * Two, it can encode and decode packages so that they can be defined and identified
 * as they come in on a socket.
 * <br>
 * <b>THIS CLASS IS NOT THREAD SAFE

 * <br/>
 * Transfer package:
 * <ul>
 * <li>START_DATA/b> - 7 bytes - FLT2002
 * <li>SIZE      - 4 bytes - size of the data package
 * <li>DATA      - should be as many bytes as the prev SIZE
 * <li>END_DATA  - 7 bytes - TLF2003
 * </ul>
 * @author Filip Hanik
 * @version $Revision: 467173 $, $Date: 2006-10-24 01:12:17 +0200 (mar., 24 oct. 2006) $
 */
public class XByteBuffer
{
    
    public static org.apache.juli.logging.Log log =
        org.apache.juli.logging.LogFactory.getLog( XByteBuffer.class );
    
    /**
     * This is a package header, 7 bytes (FLT2002)
     */
    public static final byte[] START_DATA = {70,76,84,50,48,48,50};
    
    /**
     * This is the package footer, 7 bytes (TLF2003)
     */
    public static final byte[] END_DATA = {84,76,70,50,48,48,51};
 
    /**
     * Default size on the initial byte buffer
     */
    private static final int DEF_SIZE = 2048;
 
    /**
     * Default size to extend the buffer with
     */
    private static final int DEF_EXT  = 1024;
    
    /**
     * Variable to hold the data
     */
    protected byte[] buf = null;
    
    /**
     * Current length of data in the buffer
     */
    protected int bufSize = 0;
    
    /**
     * Flag for discarding invalid packages
     * If this flag is set to true, and append(byte[],...) is called,
     * the data added will be inspected, and if it doesn't start with 
     * <code>START_DATA it will be thrown away.
     * 
     */
    protected boolean discard = true;
    
    /**
     * Constructs a new XByteBuffer
     * @param size - the initial size of the byte buffer
     * @todo use a pool of byte[] for performance
     */
    public XByteBuffer(int size, boolean discard) {
        buf = new byte[size];
        this.discard = discard;
    }
    
    public XByteBuffer(byte[] data,boolean discard) {
        this(data,data.length+128,discard);
    }
    
    public XByteBuffer(byte[] data, int size,boolean discard) {
        int length = Math.max(data.length,size);
        buf = new byte[length];
        System.arraycopy(data,0,buf,0,data.length);
        bufSize = data.length;
        this.discard = discard;
    }
    
    public int getLength() {
        return bufSize;
    }

    public void setLength(int size) {
        if ( size > buf.length ) throw new ArrayIndexOutOfBoundsException("Size is larger than existing buffer.");
        bufSize = size;
    }
    
    public void trim(int length) {
        if ( (bufSize - length) < 0 ) 
            throw new ArrayIndexOutOfBoundsException("Can't trim more bytes than are available. length:"+bufSize+" trim:"+length);
        bufSize -= length;
    }
    
    public void reset() {
        bufSize = 0;
    }
            
    public byte[] getBytesDirect() {
        return this.buf;
    }

    /**
     * Returns the bytes in the buffer, in its exact length
     */
    public byte[] getBytes() {
        byte[] b = new byte[bufSize];
        System.arraycopy(buf,0,b,0,bufSize);
        return b;
    }

    /**
     * Resets the buffer
     */
    public void clear() {
        bufSize = 0;
    }

    /**
     * Appends the data to the buffer. If the data is incorrectly formatted, ie, the data should always start with the
     * header, false will be returned and the data will be discarded.
     * @param b - bytes to be appended
     * @param off - the offset to extract data from
     * @param len - the number of bytes to append.
     * @return true if the data was appended correctly. Returns false if the package is incorrect, ie missing header or something, or the length of data is 0
     */
    public boolean append(ByteBuffer b, int len) {
        int newcount = bufSize + len;
        if (newcount > buf.length) {
            expand(newcount);
        }
        b.get(buf,bufSize,len);
        
        bufSize = newcount;
        
        if ( discard ) {
            if (bufSize > START_DATA.length && (firstIndexOf(buf, 0, START_DATA) == -1)) {
                bufSize = 0;
                log.error("Discarded the package, invalid header");
                return false;
            }
        }
        return true;

    }
    
    public boolean append(byte i) {
        int newcount = bufSize + 1;
        if (newcount > buf.length) {
            expand(newcount);
        }
        buf[bufSize] = i;
        bufSize = newcount;
        return true;
    }


    public boolean append(boolean i) {
        int newcount = bufSize + 1;
        if (newcount > buf.length) {
            expand(newcount);
        }
        XByteBuffer.toBytes(i,buf,bufSize);
        bufSize = newcount;
        return true;
    }

    public boolean append(long i) {
        int newcount = bufSize + 8;
        if (newcount > buf.length) {
            expand(newcount);
        }
        XByteBuffer.toBytes(i,buf,bufSize);
        bufSize = newcount;
        return true;
    }
    
    public boolean append(int i) {
        int newcount = bufSize + 4;
        if (newcount > buf.length) {
            expand(newcount);
        }
        XByteBuffer.toBytes(i,buf,bufSize);
        bufSize = newcount;
        return true;
    }

    public boolean append(byte[] b, int off, int len) {
        if ((off < 0) || (off > b.length) || (len < 0) ||
            ((off + len) > b.length) || ((off + len) < 0))  {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return false;
        }

        int newcount = bufSize + len;
        if (newcount > buf.length) {
            expand(newcount);
        }
        System.arraycopy(b, off, buf, bufSize, len);
        bufSize = newcount;

        if ( discard ) {
            if (bufSize > START_DATA.length && (firstIndexOf(buf, 0, START_DATA) == -1)) {
                bufSize = 0;
                log.error("Discarded the package, invalid header");
                return false;
            }
        }
        return true;
    }

    public void expand(int newcount) {
        //don't change the allocation strategy
        byte newbuf[] = new byte[Math.max(buf.length << 1, newcount)];
        System.arraycopy(buf, 0, newbuf, 0, bufSize);
        buf = newbuf;
    }
    
    public int getCapacity() {
        return buf.length;
    }


    /**
     * Internal mechanism to make a check if a complete package exists
     * within the buffer
     * @return - true if a complete package (header,compress,size,data,footer) exists within the buffer
     */
    public int countPackages() {
        return countPackages(false);
    }

    public int countPackages(boolean first)
    {
        int cnt = 0;
        int pos = START_DATA.length;
        int start = 0;

        while ( start < bufSize ) {
            //first check start header
            int index = XByteBuffer.firstIndexOf(buf,start,START_DATA);
            //if the header (START_DATA) isn't the first thing or
            //the buffer isn't even 14 bytes
            if ( index != start || ((bufSize-start)<14) ) break;
            //next 4 bytes are compress flag not needed for count packages
            //then get the size 4 bytes
            int size = toInt(buf, pos);
            //now the total buffer has to be long enough to hold
            //START_DATA.length+4+size+END_DATA.length
            pos = start + START_DATA.length + 4 + size;
            if ( (pos + END_DATA.length) > bufSize) break;
            //and finally check the footer of the package END_DATA
            int newpos = firstIndexOf(buf, pos, END_DATA);
            //mismatch, there is no package
            if (newpos != pos) break;
            //increase the packet count
            cnt++;
            //reset the values
            start = pos + END_DATA.length;
            pos = start + START_DATA.length;
            //we only want to verify that we have at least one package
            if ( first ) break;
        }
        return cnt;
    }

    /**
     * Method to check if a package exists in this byte buffer.
     * @return - true if a complete package (header,options,size,data,footer) exists within the buffer
     */
    public boolean doesPackageExist()  {
        return (countPackages(true)>0);
    }

    /**
     * Extracts the message bytes from a package.
     * If no package exists, a IllegalStateException will be thrown.
     * @param clearFromBuffer - if true, the package will be removed from the byte buffer
     * @return - returns the actual message bytes (header, compress,size and footer not included).
     */
    public XByteBuffer extractDataPackage(boolean clearFromBuffer) {
        int psize = countPackages(true);
        if (psize == 0) {
            throw new java.lang.IllegalStateException("No package exists in XByteBuffer");
        }
        int size = toInt(buf, START_DATA.length);
        XByteBuffer xbuf = BufferPool.getBufferPool().getBuffer(size,false);
        xbuf.setLength(size);
        System.arraycopy(buf, START_DATA.length + 4, xbuf.getBytesDirect(), 0, size);
        if (clearFromBuffer) {
            int totalsize = START_DATA.length + 4 + size + END_DATA.length;
            bufSize = bufSize - totalsize;
            System.arraycopy(buf, totalsize, buf, 0, bufSize);
        }
        return xbuf;

    }
    
    public ChannelData extractPackage(boolean clearFromBuffer) throws java.io.IOException {
        XByteBuffer xbuf = extractDataPackage(clearFromBuffer);
        ChannelData cdata = ChannelData.getDataFromPackage(xbuf);
        return cdata;
    }
    
    /**
     * Creates a complete data package
     * @param indata - the message data to be contained within the package
     * @param compressed - compression flag for the indata buffer
     * @return - a full package (header,size,data,footer)
     * 
     */
    public static byte[] createDataPackage(ChannelData cdata) {
//        return createDataPackage(cdata.getDataPackage());
        //avoid one extra byte array creation
        int dlength = cdata.getDataPackageLength();
        int length = getDataPackageLength(dlength);
        byte[] data = new byte[length];
        int offset = 0;
        System.arraycopy(START_DATA, 0, data, offset, START_DATA.length);
        offset += START_DATA.length;
        toBytes(dlength,data, START_DATA.length);
        offset += 4;
        cdata.getDataPackage(data,offset);
        offset += dlength;
        System.arraycopy(END_DATA, 0, data, offset, END_DATA.length);
        offset += END_DATA.length;
        return data;
    }
    
    public static byte[] createDataPackage(byte[] data, int doff, int dlength, byte[] buffer, int bufoff) {
        if ( (buffer.length-bufoff) > getDataPackageLength(dlength) ) {
            throw new ArrayIndexOutOfBoundsException("Unable to create data package, buffer is too small.");
        }
        System.arraycopy(START_DATA, 0, buffer, bufoff, START_DATA.length);
        toBytes(data.length,buffer, bufoff+START_DATA.length);
        System.arraycopy(data, doff, buffer, bufoff+START_DATA.length + 4, dlength);
        System.arraycopy(END_DATA, 0, buffer, bufoff+START_DATA.length + 4 + data.length, END_DATA.length);
        return buffer;
    }

    
    public static int getDataPackageLength(int datalength) {
        int length = 
            START_DATA.length + //header length
            4 + //data length indicator
            datalength + //actual data length
            END_DATA.length; //footer length
        return length;

    }
    
    public static byte[] createDataPackage(byte[] data) {
        int length = getDataPackageLength(data.length);
        byte[] result = new byte[length];
        return createDataPackage(data,0,data.length,result,0);
    }
    
    

//    public static void fillDataPackage(byte[] data, int doff, int dlength, XByteBuffer buf) {
//        int pkglen = getDataPackageLength(dlength);
//        if ( buf.getCapacity() <  pkglen ) buf.expand(pkglen);
//        createDataPackage(data,doff,dlength,buf.getBytesDirect(),buf.getLength());
//    }

    /**
     * Convert four bytes to an int
     * @param b - the byte array containing the four bytes
     * @param off - the offset
     * @return the integer value constructed from the four bytes
     * @exception java.lang.ArrayIndexOutOfBoundsException
     */
    public static int toInt(byte[] b,int off){
        return ( ( (int) b[off+3]) & 0xFF) +
            ( ( ( (int) b[off+2]) & 0xFF) << 8) +
            ( ( ( (int) b[off+1]) & 0xFF) << 16) +
            ( ( ( (int) b[off+0]) & 0xFF) << 24);
    }

    /**
     * Convert eight bytes to a long
     * @param b - the byte array containing the four bytes
     * @param off - the offset
     * @return the long value constructed from the eight bytes
     * @exception java.lang.ArrayIndexOutOfBoundsException
     */
    public static long toLong(byte[] b,int off){
        return ( ( (long) b[off+7]) & 0xFF) +
            ( ( ( (long) b[off+6]) & 0xFF) << 8) +
            ( ( ( (long) b[off+5]) & 0xFF) << 16) +
            ( ( ( (long) b[off+4]) & 0xFF) << 24) +
            ( ( ( (long) b[off+3]) & 0xFF) << 32) +
            ( ( ( (long) b[off+2]) & 0xFF) << 40) +
            ( ( ( (long) b[off+1]) & 0xFF) << 48) +
            ( ( ( (long) b[off+0]) & 0xFF) << 56);
    }

    
    /**
     * Converts an integer to four bytes
     * @param n - the integer
     * @return - four bytes in an array
     * @deprecated use toBytes(boolean,byte[],int)
     */
    public static byte[] toBytes(boolean bool) {
        byte[] b = new byte[1] ;
        return toBytes(bool,b,0);

    }
    
    public static byte[] toBytes(boolean bool, byte[] data, int offset) {
        data[offset] = (byte)(bool?1:0);
        return data;
    }
    
    /**
     * 
     * @param <any> long
     * @return use
     */
    public static boolean toBoolean(byte[] b, int offset) {
        return b[offset] != 0;
    }

    
    /**
     * Converts an integer to four bytes
     * @param n - the integer
     * @return - four bytes in an array
     * @deprecated use toBytes(int,byte[],int)
     */
    public static byte[] toBytes(int n) {
        return toBytes(n,new byte[4],0);
    }

    public static byte[] toBytes(int n,byte[] b, int offset) {
        b[offset+3] = (byte) (n);
        n >>>= 8;
        b[offset+2] = (byte) (n);
        n >>>= 8;
        b[offset+1] = (byte) (n);
        n >>>= 8;
        b[offset+0] = (byte) (n);
        return b;
    }

    /**
     * Converts an long to eight bytes
     * @param n - the long
     * @return - eight bytes in an array
     * @deprecated use toBytes(long,byte[],int)
     */
    public static byte[] toBytes(long n) {
        return toBytes(n,new byte[8],0);
    }
    public static byte[] toBytes(long n, byte[] b, int offset) {
        b[offset+7] = (byte) (n);
        n >>>= 8;
        b[offset+6] = (byte) (n);
        n >>>= 8;
        b[offset+5] = (byte) (n);
        n >>>= 8;
        b[offset+4] = (byte) (n);
        n >>>= 8;
        b[offset+3] = (byte) (n);
        n >>>= 8;
        b[offset+2] = (byte) (n);
        n >>>= 8;
        b[offset+1] = (byte) (n);
        n >>>= 8;
        b[offset+0] = (byte) (n);
        return b;
    }

    /**
     * Similar to a String.IndexOf, but uses pure bytes
     * @param src - the source bytes to be searched
     * @param srcOff - offset on the source buffer
     * @param find - the string to be found within src
     * @return - the index of the first matching byte. -1 if the find array is not found
     */
    public static int firstIndexOf(byte[] src, int srcOff, byte[] find){
        int result = -1;
        if (find.length > src.length) return result;
        if (find.length == 0 || src.length == 0) return result;
        if (srcOff >= src.length ) throw new java.lang.ArrayIndexOutOfBoundsException();
        boolean found = false;
        int srclen = src.length;
        int findlen = find.length;
        byte first = find[0];
        int pos = srcOff;
        while (!found) {
            //find the first byte
            while (pos < srclen){
                if (first == src[pos])
                    break;
                pos++;
            }
            if (pos >= srclen)
                return -1;

            //we found the first character
            //match the rest of the bytes - they have to match
            if ( (srclen - pos) < findlen)
                return -1;
            //assume it does exist
            found = true;
            for (int i = 1; ( (i < findlen) && found); i++)
                found = found && (find[i] == src[pos + i]);
            if (found)
                result = pos;
            else if ( (srclen - pos) < findlen)
                return -1; //no more matches possible
            else
                pos++;
        }
        return result;
    }

    
    public static Serializable deserialize(byte[] data) 
        throws IOException, ClassNotFoundException, ClassCastException {
        return deserialize(data,0,data.length);
    }
    
    public static Serializable deserialize(byte[] data, int offset, int length)  
        throws IOException, ClassNotFoundException, ClassCastException {
        return deserialize(data,offset,length,null);     
    }
    public static int invokecount = 0;
    public static Serializable deserialize(byte[] data, int offset, int length, ClassLoader[] cls) 
        throws IOException, ClassNotFoundException, ClassCastException {
        synchronized (XByteBuffer.class) { invokecount++;}
        Object message = null;
        if ( cls == null ) cls = new ClassLoader[0];
        if (data != null) {
            InputStream  instream = new ByteArrayInputStream(data,offset,length);
            ObjectInputStream stream = null;
            stream = (cls.length>0)? new ReplicationStream(instream,cls):new ObjectInputStream(instream);
            message = stream.readObject();
            instream.close();
            stream.close();
        }
        if ( message == null ) {
            return null;
        } else if (message instanceof Serializable)
            return (Serializable) message;
        else {
            throw new ClassCastException("Message has the wrong class. It should implement Serializable, instead it is:"+message.getClass().getName());
        }
    }

    /**
     * Serializes a message into cluster data
     * @param msg ClusterMessage
     * @param compress boolean
     * @return 
     * @throws IOException
     */
    public static byte[] serialize(Serializable msg) throws IOException {
        ByteArrayOutputStream outs = new ByteArrayOutputStream();
        ObjectOutputStream out = new ObjectOutputStream(outs);
        out.writeObject(msg);
        out.flush();
        byte[] data = outs.toByteArray();
        return data;
    }

    public void setDiscard(boolean discard) {
        this.discard = discard;
    }

    public boolean getDiscard() {
        return discard;
    }

}