diff options
Diffstat (limited to 'libjava/classpath/java/lang/Thread.java')
| -rw-r--r-- | libjava/classpath/java/lang/Thread.java | 193 |
1 files changed, 192 insertions, 1 deletions
diff --git a/libjava/classpath/java/lang/Thread.java b/libjava/classpath/java/lang/Thread.java index 76df1037bb5..23620543aef 100644 --- a/libjava/classpath/java/lang/Thread.java +++ b/libjava/classpath/java/lang/Thread.java @@ -1,5 +1,5 @@ /* Thread -- an independent thread of executable code - Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004 + Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation This file is part of GNU Classpath. @@ -81,6 +81,7 @@ import java.util.Map; * @author Tom Tromey * @author John Keiser * @author Eric Blake (ebb9@email.byu.edu) + * @author Andrew John Hughes (gnu_andrew@member.fsf.org) * @see Runnable * @see Runtime#exit(int) * @see #run() @@ -130,15 +131,27 @@ public class Thread implements Runnable /** The context classloader for this Thread. */ private ClassLoader contextClassLoader; + + /** This thread's ID. */ + private final long threadId; /** The next thread number to use. */ private static int numAnonymousThreadsCreated; + + /** The next thread ID to use. */ + private static long nextThreadId; + + /** The default exception handler. */ + private static UncaughtExceptionHandler defaultHandler; /** Thread local storage. Package accessible for use by * InheritableThreadLocal. */ WeakIdentityHashMap locals; + /** The uncaught exception handler. */ + UncaughtExceptionHandler exceptionHandler; + /** * Allocates a new <code>Thread</code> object. This constructor has * the same effect as <code>Thread(null, null,</code> @@ -342,6 +355,11 @@ public class Thread implements Runnable this.name = name.toString(); this.runnable = target; this.stacksize = size; + + synchronized (Thread.class) + { + this.threadId = nextThreadId++; + } priority = current.priority; daemon = current.daemon; @@ -371,6 +389,11 @@ public class Thread implements Runnable this.priority = priority; this.daemon = daemon; this.contextClassLoader = ClassLoader.getSystemClassLoader(); + synchronized (Thread.class) + { + this.threadId = nextThreadId++; + } + } /** @@ -434,6 +457,19 @@ public class Thread implements Runnable /** * Originally intended to destroy this thread, this method was never * implemented by Sun, and is hence a no-op. + * + * @deprecated This method was originally intended to simply destroy + * the thread without performing any form of cleanup operation. + * However, it was never implemented. It is now deprecated + * for the same reason as <code>suspend()</code>, + * <code>stop()</code> and <code>resume()</code>; namely, + * it is prone to deadlocks. If a thread is destroyed while + * it still maintains a lock on a resource, then this resource + * will remain locked and any attempts by other threads to + * access the resource will result in a deadlock. Thus, even + * an implemented version of this method would be still be + * deprecated, due to its unsafe nature. + * @throws NoSuchMethodError as this method was never implemented. */ public void destroy() { @@ -1000,4 +1036,159 @@ public class Thread implements Runnable } return locals; } + + /** + * Assigns the given <code>UncaughtExceptionHandler</code> to this + * thread. This will then be called if the thread terminates due + * to an uncaught exception, pre-empting that of the + * <code>ThreadGroup</code>. + * + * @param h the handler to use for this thread. + * @throws SecurityException if the current thread can't modify this thread. + * @since 1.5 + */ + public void setUncaughtExceptionHandler(UncaughtExceptionHandler h) + { + SecurityManager sm = SecurityManager.current; // Be thread-safe. + if (sm != null) + sm.checkAccess(this); + exceptionHandler = h; + } + + /** + * <p> + * Returns the handler used when this thread terminates due to an + * uncaught exception. The handler used is determined by the following: + * </p> + * <ul> + * <li>If this thread has its own handler, this is returned.</li> + * <li>If not, then the handler of the thread's <code>ThreadGroup</code> + * object is returned.</li> + * <li>If both are unavailable, then <code>null</code> is returned + * (which can only happen when the thread was terminated since + * then it won't have an associated thread group anymore).</li> + * </ul> + * + * @return the appropriate <code>UncaughtExceptionHandler</code> or + * <code>null</code> if one can't be obtained. + * @since 1.5 + */ + public UncaughtExceptionHandler getUncaughtExceptionHandler() + { + return exceptionHandler != null ? exceptionHandler : group; + } + + /** + * <p> + * Sets the default uncaught exception handler used when one isn't + * provided by the thread or its associated <code>ThreadGroup</code>. + * This exception handler is used when the thread itself does not + * have an exception handler, and the thread's <code>ThreadGroup</code> + * does not override this default mechanism with its own. As the group + * calls this handler by default, this exception handler should not defer + * to that of the group, as it may lead to infinite recursion. + * </p> + * <p> + * Uncaught exception handlers are used when a thread terminates due to + * an uncaught exception. Replacing this handler allows default code to + * be put in place for all threads in order to handle this eventuality. + * </p> + * + * @param h the new default uncaught exception handler to use. + * @throws SecurityException if a security manager is present and + * disallows the runtime permission + * "setDefaultUncaughtExceptionHandler". + * @since 1.5 + */ + public static void + setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler h) + { + SecurityManager sm = SecurityManager.current; // Be thread-safe. + if (sm != null) + sm.checkPermission(new RuntimePermission("setDefaultUncaughtExceptionHandler")); + defaultHandler = h; + } + + /** + * Returns the handler used by default when a thread terminates + * unexpectedly due to an exception, or <code>null</code> if one doesn't + * exist. + * + * @return the default uncaught exception handler. + * @since 1.5 + */ + public static UncaughtExceptionHandler getDefaultUncaughtExceptionHandler() + { + return defaultHandler; + } + + /** + * Returns the unique identifier for this thread. This ID is generated + * on thread creation, and may be re-used on its death. + * + * @return a positive long number representing the thread's ID. + * @since 1.5 + */ + public long getId() + { + return threadId; + } + + /** + * <p> + * This interface is used to handle uncaught exceptions + * which cause a <code>Thread</code> to terminate. When + * a thread, t, is about to terminate due to an uncaught + * exception, the virtual machine looks for a class which + * implements this interface, in order to supply it with + * the dying thread and its uncaught exception. + * </p> + * <p> + * The virtual machine makes two attempts to find an + * appropriate handler for the uncaught exception, in + * the following order: + * </p> + * <ol> + * <li> + * <code>t.getUncaughtExceptionHandler()</code> -- + * the dying thread is queried first for a handler + * specific to that thread. + * </li> + * <li> + * <code>t.getThreadGroup()</code> -- + * the thread group of the dying thread is used to + * handle the exception. If the thread group has + * no special requirements for handling the exception, + * it may simply forward it on to + * <code>Thread.getDefaultUncaughtExceptionHandler()</code>, + * the default handler, which is used as a last resort. + * </li> + * </ol> + * <p> + * The first handler found is the one used to handle + * the uncaught exception. + * </p> + * + * @author Tom Tromey <tromey@redhat.com> + * @author Andrew John Hughes <gnu_andrew@member.fsf.org> + * @since 1.5 + * @see Thread#getUncaughtExceptionHandler() + * @see Thread#setUncaughtExceptionHander(java.lang.Thread.UncaughtExceptionHandler) + * @see Thread#getDefaultUncaughtExceptionHandler() + * @see + * Thread#setDefaultUncaughtExceptionHandler(java.lang.Thread.UncaughtExceptionHandler) + */ + public interface UncaughtExceptionHandler + { + /** + * Invoked by the virtual machine with the dying thread + * and the uncaught exception. Any exceptions thrown + * by this method are simply ignored by the virtual + * machine. + * + * @param thr the dying thread. + * @param exc the uncaught exception. + */ + void uncaughtException(Thread thr, Throwable exc); + } } |