Thread.java

// Thread.java - Thread class.

/* Copyright (C) 1998, 1999  Cygnus Solutions

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

package java.lang;

/**
 * @author Tom Tromey <tromey@cygnus.com>
 * @date August 24, 1998 
 */

/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
 * "The Java Language Specification", ISBN 0-201-63451-1
 * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
 * Status:  Complete to version 1.1, with caveats
 * Known problems:
 *   No attempt was made to implement suspend/resume
 *     (this could be done in some cases)
 *   Various methods which assume a VM are likewise unimplemented
 *   We do implement stop() even though it is deprecated.
 */

public class Thread implements Runnable
{
  public final static int MAX_PRIORITY = 10;
  public final static int MIN_PRIORITY = 1;
  public final static int NORM_PRIORITY = 5;

  public static int activeCount ()
  {
    return currentThread().getThreadGroup().activeCount();
  }

  public void checkAccess ()
  {
    SecurityManager s = System.getSecurityManager();
    if (s != null)
      s.checkAccess(this);
  }

  public native int countStackFrames ();
  public static native Thread currentThread ();
  public native void destroy ();
  public static native void dumpStack ();

  public static int enumerate (Thread[] threads)
  {
    return currentThread().group.enumerate(threads);
  }

  public final String getName ()
  {
    return name;
  }

  public final int getPriority ()
  {
    return priority;
  }

  public final ThreadGroup getThreadGroup ()
  {
    return group;
  }

  public native void interrupt ();

  public static boolean interrupted ()
  {
    return currentThread().isInterrupted();
  }

  // FIXME: it seems to me that this should be synchronized.
  public boolean isInterrupted ()
  {
    boolean r = interrupt_flag;
    interrupt_flag = false;
    return r;
  }

  public final boolean isAlive ()
  {
    return alive_flag;
  }

  public final boolean isDaemon ()
  {
    return daemon_flag;
  }

  public final void join () throws InterruptedException
  {
    join (0, 0);
  }

  public final void join (long timeout) throws InterruptedException
  {
    join (timeout, 0);
  }

  public final native void join (long timeout, int nanos)
    throws InterruptedException;

  public final native void resume ();

  // This method exists only to avoid a warning from the C++ compiler.
  private static final native void run__ (Object obj);
  private native final void finish_ ();
  private final void run_ ()
  {
    try
      {
	run ();
      }
    catch (Throwable e)
      {
	// Uncaught exceptions are forwarded to the ThreadGroup.  If
	// this results in an uncaught exception, that is ignored.
	try
	  {
	    group.uncaughtException(this, e);
	  }
	catch (Throwable f)
	  {
	    // Nothing.
	  }
      }
    finish_ ();
  }

  public void run ()
  {
    if (runnable != null)
      runnable.run();
  }

  public final void setDaemon (boolean status)
  {
    checkAccess ();
    if (isAlive ())
      throw new IllegalThreadStateException ();
    daemon_flag = status;
  }

  // TODO12:
  // public ClassLoader getContextClassLoader()
  // {
  // }

  // TODO12:
  // public void setContextClassLoader(ClassLoader cl)
  // {
  // }

  public final void setName (String n)
  {
    checkAccess ();
    // The Class Libraries book says ``threadName cannot be null''.  I
    // take this to mean NullPointerException.
    if (n == null)
      throw new NullPointerException ();
    name = n;
  }

  public final native void setPriority (int newPriority);

  public static void sleep (long timeout) throws InterruptedException
  {
    sleep (timeout, 0);
  }

  public static native void sleep (long timeout, int nanos)
    throws InterruptedException;
  public synchronized native void start ();

  public final void stop ()
  {
    // Argument doesn't matter, because this is no longer
    // supported.
    stop (null);
  }

  public final synchronized native void stop (Throwable e);
  public final native void suspend ();

  private final native void initialize_native ();

  private final synchronized static String gen_name ()
  {
    String n;
    n = "Thread-" + nextThreadNumber;
    ++nextThreadNumber;
    return n;
  }

  public Thread (ThreadGroup g, Runnable r, String n)
  {
    // Note that CURRENT can be null when we are creating the very
    // first thread.  That's why we check it below.
    Thread current = currentThread ();

    if (g != null)
      {
	// If CURRENT is null, then we are creating the first thread.
	// In this case we don't do the security check.
	if (current != null)
	  g.checkAccess();
      }
    else
      g = current.getThreadGroup();

    // The Class Libraries book says ``threadName cannot be null''.  I
    // take this to mean NullPointerException.
    if (n == null)
      throw new NullPointerException ();

    name = n;
    group = g;
    g.add(this);
    runnable = r;

    data = null;
    interrupt_flag = false;
    alive_flag = false;
    if (current != null)
      {
	daemon_flag = current.isDaemon();
	priority = current.getPriority();
      }
    else
      {
	daemon_flag = false;
	priority = NORM_PRIORITY;
      }

    initialize_native ();
  }

  public Thread ()
  {
    this (null, null, gen_name ());
  }

  public Thread (Runnable r)
  {
    this (null, r, gen_name ());
  }

  public Thread (String n)
  {
    this (null, null, n);
  }

  public Thread (ThreadGroup g, Runnable r)
  {
    this (g, r, gen_name ());
  }

  public Thread (ThreadGroup g, String n)
  {
    this (g, null, n);
  }

  public Thread (Runnable r, String n)
  {
    this (null, r, n);
  }

  public String toString ()
  {
    return "Thread[" + name + "," + priority + "," + group.getName() + "]";
  }

  public static native void yield ();

  // Private data.
  private ThreadGroup group;
  private String name;
  private Runnable runnable;
  private int priority;
  private boolean daemon_flag;
  private boolean interrupt_flag;
  private boolean alive_flag;

  // This is a bit odd.  We need a way to represent some data that is
  // manipulated only by the native side of this class.  We represent
  // it as a Java object reference.  However, it is not actually a
  // Java object.
  private Object data;

  // Next thread number to assign.
  private static int nextThreadNumber = 0;
}