thread.java

gcc的组建

   *
   * @param group the group to put the Thread into
   * @param target the Runnable object to execute
   * @param name the name for the Thread
   * @param size the stack size, in bytes; 0 to be ignored
   * @throws NullPointerException if name is null
   * @throws SecurityException if this thread cannot access <code>group</code>
   * @throws IllegalThreadStateException if group is destroyed
   * @since 1.4
   */
  public Thread(ThreadGroup group, Runnable target, String name, long size)
  {
    // Just ignore stackSize for now.
    this(currentThread(), group, target, name);
  }

  private Thread (Thread current, ThreadGroup g, Runnable r, String n)
  {
    // Make sure the current thread may create a new thread.
    checkAccess();
    
    // The Class Libraries book says ``threadName cannot be null''.  I
    // take this to mean NullPointerException.
    if (n == null)
      throw new NullPointerException ();
      
    if (g == null)
      {
	// If CURRENT is null, then we are bootstrapping the first thread. 
	// Use ThreadGroup.root, the main threadgroup.
	if (current == null)
	  group = ThreadGroup.root;
	else
	  group = current.getThreadGroup();
      }
    else
      group = g;
      
    data = null;
    interrupt_flag = false;
    alive_flag = false;
    startable_flag = true;

    if (current != null)
      {
	group.checkAccess();

	daemon = current.isDaemon();
        int gmax = group.getMaxPriority();
	int pri = current.getPriority();
	priority = (gmax < pri ? gmax : pri);
	contextClassLoader = current.contextClassLoader;
	InheritableThreadLocal.newChildThread(this);
      }
    else
      {
	daemon = false;
	priority = NORM_PRIORITY;
      }

    name = n;
    group.addThread(this);
    runnable = r;

    initialize_native ();
  }

  /**
   * Get the number of active threads in the current Thread's ThreadGroup.
   * This implementation calls
   * <code>currentThread().getThreadGroup().activeCount()</code>.
   *
   * @return the number of active threads in the current ThreadGroup
   * @see ThreadGroup#activeCount()
   */
  public static int activeCount()
  {
    return currentThread().group.activeCount();
  }

  /**
   * Check whether the current Thread is allowed to modify this Thread. This
   * passes the check on to <code>SecurityManager.checkAccess(this)</code>.
   *
   * @throws SecurityException if the current Thread cannot modify this Thread
   * @see SecurityManager#checkAccess(Thread)
   */
  public final void checkAccess()
  {
    SecurityManager sm = System.getSecurityManager();
    if (sm != null)
      sm.checkAccess(this);
  }

  /**
   * Count the number of stack frames in this Thread.  The Thread in question
   * must be suspended when this occurs.
   *
   * @return the number of stack frames in this Thread
   * @throws IllegalThreadStateException if this Thread is not suspended
   * @deprecated pointless, since suspend is deprecated
   */
  public native int countStackFrames();

  /**
   * Get the currently executing Thread.
   *
   * @return the currently executing Thread
   */
  public static native Thread currentThread();

  /**
   * Originally intended to destroy this thread, this method was never
   * implemented by Sun, and is hence a no-op.
   */
  public void destroy()
  {
    throw new NoSuchMethodError();
  }
  
  /**
   * Print a stack trace of the current thread to stderr using the same
   * format as Throwable's printStackTrace() method.
   *
   * @see Throwable#printStackTrace()
   */
  public static void dumpStack()
  {
    (new Exception("Stack trace")).printStackTrace();
  }

  /**
   * Copy every active thread in the current Thread's ThreadGroup into the
   * array. Extra threads are silently ignored. This implementation calls
   * <code>getThreadGroup().enumerate(array)</code>, which may have a
   * security check, <code>checkAccess(group)</code>.
   *
   * @param array the array to place the Threads into
   * @return the number of Threads placed into the array
   * @throws NullPointerException if array is null
   * @throws SecurityException if you cannot access the ThreadGroup
   * @see ThreadGroup#enumerate(Thread[])
   * @see #activeCount()
   * @see SecurityManager#checkAccess(ThreadGroup)
   */
  public static int enumerate(Thread[] array)
  {
    return currentThread().group.enumerate(array);
  }
  
  /**
   * Get this Thread's name.
   *
   * @return this Thread's name
   */
  public final String getName()
  {
    return name;
  }

  /**
   * Get this Thread's priority.
   *
   * @return the Thread's priority
   */
  public final int getPriority()
  {
    return priority;
  }

  /**
   * Get the ThreadGroup this Thread belongs to. If the thread has died, this
   * returns null.
   *
   * @return this Thread's ThreadGroup
   */
  public final ThreadGroup getThreadGroup()
  {
    return group;
  }

  /**
   * Checks whether the current thread holds the monitor on a given object.
   * This allows you to do <code>assert Thread.holdsLock(obj)</code>.
   *
   * @param obj the object to test lock ownership on.
   * @return true if the current thread is currently synchronized on obj
   * @throws NullPointerException if obj is null
   * @since 1.4
   */
  public static native boolean holdsLock(Object obj);

  /**
   * Interrupt this Thread. First, there is a security check,
   * <code>checkAccess</code>. Then, depending on the current state of the
   * thread, various actions take place:
   *
   * <p>If the thread is waiting because of {@link #wait()},
   * {@link #sleep(long)}, or {@link #join()}, its <i>interrupt status</i>
   * will be cleared, and an InterruptedException will be thrown. Notice that
   * this case is only possible if an external thread called interrupt().
   *
   * <p>If the thread is blocked in an interruptible I/O operation, in
   * {@link java.nio.channels.InterruptibleChannel}, the <i>interrupt
   * status</i> will be set, and ClosedByInterruptException will be thrown.
   *
   * <p>If the thread is blocked on a {@link java.nio.channels.Selector}, the
   * <i>interrupt status</i> will be set, and the selection will return, with
   * a possible non-zero value, as though by the wakeup() method.
   *
   * <p>Otherwise, the interrupt status will be set.
   *
   * @throws SecurityException if you cannot modify this Thread
   */
  public native void interrupt();

  /**
   * Determine whether the current Thread has been interrupted, and clear
   * the <i>interrupted status</i> in the process.
   *
   * @return whether the current Thread has been interrupted
   * @see #isInterrupted()
   */
  public static boolean interrupted()
  {
    return currentThread().isInterrupted(true);
  }

  /**
   * Determine whether the given Thread has been interrupted, but leave
   * the <i>interrupted status</i> alone in the process.
   *
   * @return whether the Thread has been interrupted
   * @see #interrupted()
   */
  public boolean isInterrupted()
  {
    return interrupt_flag;
  }

  /**
   * Determine whether this Thread is alive. A thread which is alive has
   * started and not yet died.
   *
   * @return whether this Thread is alive
   */
  public final synchronized boolean isAlive()
  {
    return alive_flag;
  }

  /**
   * Tell whether this is a daemon Thread or not.
   *
   * @return whether this is a daemon Thread or not
   * @see #setDaemon(boolean)
   */
  public final boolean isDaemon()
  {
    return daemon;
  }

  /**
   * Wait forever for the Thread in question to die.
   *
   * @throws InterruptedException if the Thread is interrupted; it's
   *         <i>interrupted status</i> will be cleared
   */
  public final void join() throws InterruptedException
  {
    join(0, 0);
  }

  /**
   * Wait the specified amount of time for the Thread in question to die.
   *
   * @param ms the number of milliseconds to wait, or 0 for forever
   * @throws InterruptedException if the Thread is interrupted; it's
   *         <i>interrupted status</i> will be cleared
   */
  public final void join(long ms) throws InterruptedException
  {
    join(ms, 0);
  }

  /**
   * Wait the specified amount of time for the Thread in question to die.
   *
   * <p>Note that 1,000,000 nanoseconds == 1 millisecond, but most VMs do
   * not offer that fine a grain of timing resolution. Besides, there is
   * no guarantee that this thread can start up immediately when time expires,
   * because some other thread may be active.  So don't expect real-time
   * performance.
   *
   * @param ms the number of milliseconds to wait, or 0 for forever
   * @param ns the number of extra nanoseconds to sleep (0-999999)
   * @throws InterruptedException if the Thread is interrupted; it's
   *         <i>interrupted status</i> will be cleared
   * @throws IllegalArgumentException if ns is invalid
   * @XXX A ThreadListener would be nice, to make this efficient.
   */
  public final native void join(long ms, int ns)
    throws InterruptedException;

  /**
   * Resume a suspended thread.