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 *

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 *     notice, this list of conditions and the following disclaimer.

 *

 *   - Redistributions in binary form must reproduce the above copyright

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 *

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

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 */

/*

 * This source code is provided to illustrate the usage of a given feature

 * or technique and has been deliberately simplified. Additional steps

 * required for a production-quality application, such as security checks,

 * input validation and proper error handling, might not be present in

 * this sample code.

 */

import java.io.*;

import java.net.*;

import java.lang.Byte;

/**

 * Simple Java "server" using the Poller class

 * to multiplex on incoming connections.  Note

 * that handoff of events, via linked Q is not

 * actually be a performance booster here, since

 * the processing of events is cheaper than

 * the overhead in scheduling/executing them.

 * Although this demo does allow for concurrency

 * in handling connections, it uses a rather

 * primitive "gang scheduling" policy to keep

 * the code simpler.

 */

public class PollingServer

{

  public final static int MAXCONN    = 10000;

  public final static int PORTNUM    = 4444;

  public final static int BYTESPEROP = 10;

  /**

   * This synchronization object protects access to certain

   * data (bytesRead,eventsToProcess) by concurrent Consumer threads.

   */

  private final static Object eventSync = new Object();

  private static InputStream[] instr = new InputStream[MAXCONN];

  private static int[] mapping = new int[65535];

  private static LinkedQueue linkedQ = new LinkedQueue();

  private static int bytesRead = 0;

  private static int bytesToRead;

  private static int eventsToProcess=0;

  public PollingServer(int concurrency) {

    Socket[] sockArr = new Socket[MAXCONN];

    long timestart, timestop;

    short[] revents = new short[MAXCONN];

    int[] fds = new int[MAXCONN];

    int bytes;

    Poller Mux;

    int serverFd;

    int totalConn=0;

    int connects=0;

    System.out.println ("Serv: Initializing port " + PORTNUM);

    try {

      ServerSocket skMain = new ServerSocket (PORTNUM);

      /*

       * Create the Poller object Mux, allow for up to MAXCONN

       * sockets/filedescriptors to be polled.

       */

      Mux = new Poller(MAXCONN);

      serverFd = Mux.add(skMain, Poller.POLLIN);

      Socket ctrlSock = skMain.accept();

      BufferedReader ctrlReader =

        new BufferedReader(new InputStreamReader(ctrlSock.getInputStream()));

      String ctrlString = ctrlReader.readLine();

      bytesToRead = Integer.valueOf(ctrlString).intValue();

      ctrlString = ctrlReader.readLine();

      totalConn = Integer.valueOf(ctrlString).intValue();

      System.out.println("Receiving " + bytesToRead + " bytes from " +

                         totalConn + " client connections");

      timestart = System.currentTimeMillis();

      /*

       * Start the consumer threads to read data.

       */

      for (int consumerThread = 0;

           consumerThread < concurrency; consumerThread++ ) {

        new Consumer(consumerThread).start();

      }

      /*

       * Take connections, read Data

       */

      int numEvents=0;

      while ( bytesRead < bytesToRead ) {

        int loopWaits=0;

        while (eventsToProcess > 0) {

          synchronized (eventSync) {

            loopWaits++;

            if (eventsToProcess <= 0) break;

            try { eventSync.wait(); } catch (Exception e) {e.printStackTrace();};

          }

        }

        if (loopWaits > 1)

          System.out.println("Done waiting...loops = " + loopWaits +

                             " events " + numEvents +

                             " bytes read : " + bytesRead );

        if (bytesRead >= bytesToRead) break; // may be done!

        /*

         * Wait for events

         */

        numEvents = Mux.waitMultiple(100, fds, revents);

        synchronized (eventSync) {

          eventsToProcess = numEvents;

        }

        /*

         * Process all the events we got from Mux.waitMultiple

         */

        int cnt = 0;

        while ( (cnt < numEvents) && (bytesRead < bytesToRead) ) {

          int fd = fds[cnt];

          if (revents[cnt] == Poller.POLLIN) {

            if (fd == serverFd) {

              /*

               * New connection coming in on the ServerSocket

               * Add the socket to the Mux, keep track of mapping

               * the fdval returned by Mux.add to the connection.

               */

              sockArr[connects] = skMain.accept();

              instr[connects] = sockArr[connects].getInputStream();

              int fdval = Mux.add(sockArr[connects], Poller.POLLIN);

              mapping[fdval] = connects;

              synchronized(eventSync) {

                eventsToProcess--; // just processed this one!

              }

              connects++;

            } else {

              /*

               * We've got data from this client connection.

               * Put it on the queue for the consumer threads to process.

               */

              linkedQ.put(new Integer(fd));

            }

          } else {

            System.out.println("Got revents[" + cnt + "] == " + revents[cnt]);

          }

          cnt++;

        }

      }

      timestop = System.currentTimeMillis();

      System.out.println("Time for all reads (" + totalConn +

                         " sockets) : " + (timestop-timestart));

      // Tell the client it can now go away

      byte[] buff = new byte[BYTESPEROP];

      ctrlSock.getOutputStream().write(buff,0,BYTESPEROP);

      // Tell the cunsumer threads they can exit.

      for (int cThread = 0; cThread < concurrency; cThread++ ) {

        linkedQ.put(new Integer(-1));

      }

    } catch (Exception exc) { exc.printStackTrace(); }

  }

  /*

   * main ... just check if a concurrency was specified

   */

  public static void main (String args[])

  {

    int concurrency;

    if (args.length == 1)

      concurrency = java.lang.Integer.valueOf(args[0]).intValue();

    else

      concurrency = Poller.getNumCPUs() + 1;

    PollingServer server = new PollingServer(concurrency);

  }

  /*

   * This class is for handling the Client data.

   * The PollingServer spawns off a number of these based upon

   * the number of CPUs (or concurrency argument).

   * Each just loops grabbing events off the queue and

   * processing them.

   */

  class Consumer extends Thread {

    private int threadNumber;

    public Consumer(int i) { threadNumber = i; }

    public void run() {

      byte[] buff = new byte[BYTESPEROP];

      int bytes = 0;

      InputStream instream;

      while (bytesRead < bytesToRead) {

        try {

          Integer Fd = (Integer) linkedQ.take();

          int fd = Fd.intValue();

          if (fd == -1) break; /* got told we could exit */

          /*

           * We have to map the fd value returned from waitMultiple

           * to the actual input stream associated with that fd.

           * Take a look at how the Mux.add() was done to see how

           * we stored that.

           */

          int map = mapping[fd];

          instream = instr[map];

          bytes = instream.read(buff,0,BYTESPEROP);

        } catch (Exception e) { System.out.println(e.toString()); }

        if (bytes > 0) {

          /*

           * Any real server would do some synchronized and some

           * unsynchronized work on behalf of the client, and

           * most likely send some data back...but this is a

           * gross oversimplification.

           */

          synchronized(eventSync) {

            bytesRead += bytes;

            eventsToProcess--;

            if (eventsToProcess <= 0) {

              eventSync.notify();

            }

          }

        }

      }

    }

  }

}