/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package chapters.appenders;
  
  import org.slf4j.Logger;
  
  import ch.qos.logback.classic.LoggerContext;
  import ch.qos.logback.classic.encoder.PatternLayoutEncoder;
  import ch.qos.logback.classic.spi.ILoggingEvent;
  import ch.qos.logback.core.FileAppender;
  import ch.qos.logback.core.encoder.EchoEncoder;
  
  public class IO extends Thread {
    static String msgLong = "ABCDEGHIJKLMNOPQRSTUVWXYZabcdeghijklmnopqrstuvwxyz1234567890";
    static String msgShort = "Hello";
    static boolean scarceCPU;
    static int numThreads;
    static long l;
    static boolean longMessage;
    long len;
    boolean buffered;
    boolean immediateFlush;
    Logger logger;
    LoggerContext context;
    double throughput;
  
    public IO(boolean _buffered, boolean _immediateFlush, long _len) {
      this.len = _len;
      this.buffered = _buffered;
      this.immediateFlush = _immediateFlush;
      context = new LoggerContext();
      logger = context.getLogger("logger-" + getName());
  
      // A FileAppender is created according to the buffering and
      // immediate flush setting of this IO instance.
      FileAppender<ILoggingEvent> fa = new FileAppender<ILoggingEvent>();
  
      if (longMessage) {
        PatternLayoutEncoder pa = new PatternLayoutEncoder();
        pa.setPattern("%r %5p %c [%t] - %m%n");
        pa.setContext(context);
        pa.start();
        fa.setEncoder(pa);
      } else {
        fa.setEncoder(new EchoEncoder<ILoggingEvent>());
      }
  
      fa.setFile(getName() + ".log");
      fa.setAppend(false);
      fa.setContext(context);
      fa.start();
      
    }
  
    public static void main(String[] argv) throws Exception {
      if (argv.length != 4) {
        usage("Wrong number of arguments.");
      }
  
      l = Integer.parseInt(argv[0]);
      numThreads = Integer.parseInt(argv[1]);
      scarceCPU = "true".equalsIgnoreCase(argv[2]);
      longMessage = "long".equalsIgnoreCase(argv[3]);
  
      // ----------------------------------------------------
      // first test with unbuffered IO and immediate flushing
      perfCase(false, true, l);
  
      // ----------------------------------------------------
      // Second test with unbuffered IO and no immediate flushing
      perfCase(false, false, l);
  
      // ----------------------------------------------------
      // Third test with buffered IO and no immediate flushing
      perfCase(true, false, l);
  
      // There is no fourth test as buffered IO and immediate flushing
      // do not make sense.
    }
  
    static void usage(String msg) {
      System.err.println(msg);
      System.err.println("Usage: java " + IO.class.getName() +
        " runLength numThreads scarceCPU (short|long)\n" +
        "   runLength (integer) the number of logs to generate perthread\n" +
        "   numThreads (integer) the number of threads.\n" +
        "   scarceCPU (boolean) if true an additional CPU intensive thread is created\n" +
        "   (short|long) length of log messages.");
     System.exit(1);
   }
 
   static void perfCase(boolean buffered, boolean immediateFlush, long len)
     throws Exception {
     IO[] threads = new IO[numThreads];
     Counter counterThread = null;
 
     if (scarceCPU) {
       counterThread = new Counter();
       counterThread.start();
     }
 
     // First create the threads 
     for (int i = 0; i < numThreads; i++) {
       threads[i] = new IO(buffered, immediateFlush, len);
     }
 
     // then start them
     for (int i = 0; i < numThreads; i++) {
       threads[i].start();
     }
 
     // wait for them to stop, compute the average throughput
     double sum = 0;
 
     for (int i = 0; i < numThreads; i++) {
       threads[i].join();
       sum += threads[i].throughput;
     }
 
     if (scarceCPU) {
       // setting the interrupted field will cause counterThread to stop
       counterThread.interrupted = true;
       counterThread.join();
     }
 
     System.out.println("On average throughput of " + (sum / numThreads)*1000 +
       " logs per microsecond.");
     System.out.println("------------------------------------------------");
   }
 
   public void run() {
     String msg = msgShort;
 
     if (longMessage) {
       msg = msgLong;
     }
 
     long before = System.nanoTime();
 
     for (int i = 0; i < len; i++) {
       logger.debug(msg);
     }
 
     throughput = (len * 1.0) / (System.nanoTime() - before);
     System.out.println(getName() + ", buffered: " + buffered +
       ", immediateFlush: " + immediateFlush + ", throughput: " + throughput +
       " logs per nanosecond.");
   }
 }
 
 
 class Counter extends Thread {
   public boolean interrupted = false;
   public double counter = 0;
 
   public void run() {
     long before = System.nanoTime();
 
     while (!interrupted) {
       if(counter % 1000 == 0) {
           Thread.yield();
       }
       counter += 1.0;
     }
 
     double tput = (counter * 1.0) / (System.nanoTime() - before);
     System.out.println("Counter thread " + getName() +
       " incremented counter by " + tput + " per nanosecond.");
   }
 }