DacapoTomcat.java

class Benchmark {
  public final boolean run() {
    if (++iteration == 1) prepare();
    if (validateOutput) {
      System.setOut(out); // this is where System.out is redefined
      out.openLog();
    }
    try { iterate(); }
    finally {
      if (validateOutput) {
        out.closeLog(); // this sets out.log to null
        out.setOut(savedOut);
      }
    }
  }
  TeeOutputStream out; // really a TeePritnStream that just forwards to a TeeOutputStream
  protected int iteration = 0;
  abstract public void prepare();
  abstract public void cleanup();
  abstract public void iterate();
}

class Tomcat extends Benchmark {
  public Tomcat() { controller = new Control(); }
  public void prepare() { controller.prepare(); } // starts the server thread
  public void cleanup() { controller.cleanup(); } // stops the server thread
  public void iterate() {
    controller.startIteration(); // tell server (using a http request) to start the webapp "examples"
    // ... start client threads, wait until they finish ...
    controller.stopIteration(); // tell the server (using a http request) to stop serving the webapp "examples"
  }
}

class TeeOutputStream {
  private OutputStream log = null;
  public void closeLog() { log = null; } // ... plus other stuff
  public void write(int b) {
    if (log != null) log.write(b);
  }
  // ...
}