AsyncSocketChannelOutputBuffer.java

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package com.sun.grizzly.aio.http;

import java.io.IOException;
import java.nio.ByteBuffer;
import com.sun.grizzly.aio.util.AIOOutputWriter;
import com.sun.grizzly.http.HttpWorkerThread;
import com.sun.grizzly.http.SocketChannelOutputBuffer;
import com.sun.grizzly.tcp.Response;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.Channel;
import java.util.concurrent.ArrayBlockingQueue;

/**
 * Output buffer.
 * Buffer the bytes until the {@link ByteChunk} is full or the request
 * is completed.
 * 
 * @author Jean-Francois Arcand
 * @author Scott Oaks
 */
public class AsyncSocketChannelOutputBuffer extends SocketChannelOutputBuffer{

    private ByteBufferRecycler bbr  = null;

    
    private static ArrayBlockingQueue<ByteBuffer> cachedByteBuffers;

    
    private AIOOutputWriter.Connection connection;

    // ----------------------------------------------------------- Constructors
    

    /**
     * Alternate constructor.
     */
    public AsyncSocketChannelOutputBuffer(Response response, 
            int headerBufferSize, boolean useSocketBuffer) {
        super(response,headerBufferSize, useSocketBuffer);

        if (AIOOutputWriter.ASYNC_WRITE){
            bbr = new ByteBufferRecycler(); 
        }
    }

    
    /**
     * Guess the number of {@link ByteBuffer} allowed to be cached. When the 
     * limit is reached, {@link ByteBuffer} are not re-used and candidate for
     * garbage collection.
     */
    private void guessCachedByteBufferSize(int headerBufferSize){
        //Allocate half of the free space.
        int size = (int)
                (Runtime.getRuntime().freeMemory()/headerBufferSize)/2;
        
        int maxThreads = ((HttpWorkerThread)Thread.currentThread()).getProcessorTask()
                .getSelectorThread().getMaxThreads();
        size = size/maxThreads;
        cachedByteBuffers = new ArrayBlockingQueue<ByteBuffer>(size);
    }

    
    @Override
    protected ByteBuffer createByteBuffer(int size){
        return ByteBuffer.allocateDirect(size);
    }

    
    /**
     * Set the underlying socket output stream.
     */
    @Override
    public void setChannel(Channel channel) {
        this.channel = channel;
        if (channel instanceof AsynchronousSocketChannel){
            connection = new AIOOutputWriter.Connection
                    ((AsynchronousSocketChannel)channel, bbr);
        }
    }

    
    /**
     * Flush the buffer by looping until the {@link ByteBuffer} is empty
     * @param bb the ByteBuffer to write.
     */   
    @Override
    public void flushChannel(ByteBuffer bb) throws IOException{
        if (AIOOutputWriter.ASYNC_WRITE && cachedByteBuffers == null){
            guessCachedByteBufferSize(bb.capacity());
        }
        
        AIOOutputWriter.flushChannel(connection, bb);
        if (AIOOutputWriter.ASYNC_WRITE){
            bb = cachedByteBuffers.poll();
            if (bb == null){
                bb = createByteBuffer(outputByteBuffer.capacity());
            }
            outputByteBuffer = bb;
        } else {
            bb.clear();
        }
    }


    /** 
     * Recycle {@link ByteBuffer}. If the {@link AsyncSocketChannelOutputBuffer#cachedByteBuffers}, 
     * do not cache
     */
    static class ByteBufferRecycler implements AIOOutputWriter.ByteBufferHandler{
        public void completed(ByteBuffer bb) {
            bb.clear();
            cachedByteBuffers.offer(bb);
        }
    }

}