Smart Batching

FileTransport.java

package smart;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;

public class FileTransport implements Transport {

    private final RandomAccessFile file;

    public FileTransport(String fileName) throws FileNotFoundException {
        this.file =  new RandomAccessFile(new File(fileName), "rw");
    }

    public void send(ByteBuffer buffer) throws Exception {
        file.write(buffer.array());
    }

    public int maxPacketSize() {
        return 4096;
    }
}

IdleStrategy.java

package smart;

import java.util.concurrent.locks.LockSupport;

public interface IdleStrategy {
    void idle();

    enum ParkStrategy implements IdleStrategy {
        DEFAULT(100);

        final long sleepPeriodNs;

        ParkStrategy(long sleepPeriodNs) {
            this.sleepPeriodNs = sleepPeriodNs;
        }

        public void idle() {
            LockSupport.parkNanos(sleepPeriodNs);
        }
    }
}

Main.java

package smart;

import org.jctools.queues.MpscArrayQueue;

import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Main {
    public static void main(String... args) throws FileNotFoundException {
        final Scanner s = new Scanner(System.in);
        final ExecutorService consumerExecutor = Executors.newSingleThreadExecutor();
        final ExecutorService producerExecutor = Executors.newFixedThreadPool(50);

        final Transport transport = new FileTransport("awesome-file");
        final MpscArrayQueue<Message> queue = new MpscArrayQueue<Message>(100000);
        final IdleStrategy idleStrategy = IdleStrategy.ParkStrategy.DEFAULT;

        final MessageBatcher messageBatcher = new MessageBatcher(transport, queue, idleStrategy);

        consumerExecutor.submit(messageBatcher);

        producerExecutor.submit(new Producer(queue));
        producerExecutor.submit(new Producer(queue));
        producerExecutor.submit(new Producer(queue));
        producerExecutor.submit(new Producer(queue));
        producerExecutor.submit(new Producer(queue));

        System.out.println("Press enter to continue.....");
        s.nextLine();


        consumerExecutor.shutdownNow();
        producerExecutor.shutdownNow();
    }


    static class Producer implements Runnable {

        private MpscArrayQueue<Message> queue;

        Producer(MpscArrayQueue<Message> queue) {
            this.queue = queue;
        }

        public void run() {
            for(int i=0; i < 100000000; i ++) {
                queue.offer(new Message("Hello: " + i));
            }
        }
    }
}

Message.java

package smart;

public final class Message {

    private String message;

    public Message(String message) {
        this.message = message;
    }

    public int size() {
        return message.length();
    }

    public byte[] getBytes() {
        return message.getBytes();
    }
}

MessageBatcher.java

package smart;

import org.jctools.queues.MpscArrayQueue;

import java.nio.ByteBuffer;


public final class MessageBatcher implements Runnable {

    private final MpscArrayQueue<Message> queue;
    private final ByteBuffer buffer;
    private final Transport transport;
    private final IdleStrategy waitIdleStrategy;

    public MessageBatcher(final Transport transport, final MpscArrayQueue<Message> queue, final IdleStrategy waitStrategy) {
        this.transport = transport;
        this.buffer = ByteBuffer.allocate(transport.maxPacketSize());
        this.queue = queue;
        this.waitIdleStrategy = waitStrategy;
    }

    public void run() {
        while (!Thread.currentThread().isInterrupted()) {
            while(queue.peek() == null) {
                waitIdleStrategy.idle(); //sleep for a given period when idle.
            }

            Message message;

            while((message = queue.poll()) != null) {
                if (message.size() > buffer.remaining()){ sendBuffer();}
                buffer.put(message.getBytes());
            }
            sendBuffer();
        }
    }

    private void sendBuffer(){
        buffer.flip();
        try {
            transport.send(buffer);
        } catch (Exception e) {
            e.printStackTrace();
        }
        buffer.clear();
    }
}

Transport.java

package smart;

import java.nio.ByteBuffer;

public interface Transport {
    void send(ByteBuffer buffer) throws Exception;
    int maxPacketSize();
}