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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/lang/Thread.java
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+/* Thread -- an independent thread of executable code
+ Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
+ Free Software Foundation
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+package java.lang;
+
+import gnu.classpath.VMStackWalker;
+import gnu.java.util.WeakIdentityHashMap;
+
+import java.lang.management.ManagementFactory;
+import java.lang.management.ThreadInfo;
+import java.lang.management.ThreadMXBean;
+
+import java.security.Permission;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/* 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: Believed complete to version 1.4, with caveats. We do not
+ * implement the deprecated (and dangerous) stop, suspend, and resume
+ * methods. Security implementation is not complete.
+ */
+
+/**
+ * Thread represents a single thread of execution in the VM. When an
+ * application VM starts up, it creates a non-daemon Thread which calls the
+ * main() method of a particular class. There may be other Threads running,
+ * such as the garbage collection thread.
+ *
+ * <p>Threads have names to identify them. These names are not necessarily
+ * unique. Every Thread has a priority, as well, which tells the VM which
+ * Threads should get more running time. New threads inherit the priority
+ * and daemon status of the parent thread, by default.
+ *
+ * <p>There are two methods of creating a Thread: you may subclass Thread and
+ * implement the <code>run()</code> method, at which point you may start the
+ * Thread by calling its <code>start()</code> method, or you may implement
+ * <code>Runnable</code> in the class you want to use and then call new
+ * <code>Thread(your_obj).start()</code>.
+ *
+ * <p>The virtual machine runs until all non-daemon threads have died (either
+ * by returning from the run() method as invoked by start(), or by throwing
+ * an uncaught exception); or until <code>System.exit</code> is called with
+ * adequate permissions.
+ *
+ * <p>It is unclear at what point a Thread should be added to a ThreadGroup,
+ * and at what point it should be removed. Should it be inserted when it
+ * starts, or when it is created? Should it be removed when it is suspended
+ * or interrupted? The only thing that is clear is that the Thread should be
+ * removed when it is stopped.
+ *
+ * @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()
+ * @see #start()
+ * @see ThreadLocal
+ * @since 1.0
+ * @status updated to 1.4
+ */
+public class Thread implements Runnable
+{
+ /** The minimum priority for a Thread. */
+ public static final int MIN_PRIORITY = 1;
+
+ /** The priority a Thread gets by default. */
+ public static final int NORM_PRIORITY = 5;
+
+ /** The maximum priority for a Thread. */
+ public static final int MAX_PRIORITY = 10;
+
+ /** The underlying VM thread, only set when the thread is actually running.
+ */
+ volatile VMThread vmThread;
+
+ /**
+ * The group this thread belongs to. This is set to null by
+ * ThreadGroup.removeThread when the thread dies.
+ */
+ volatile ThreadGroup group;
+
+ /** The object to run(), null if this is the target. */
+ final Runnable runnable;
+
+ /** The thread name, non-null. */
+ volatile String name;
+
+ /** Whether the thread is a daemon. */
+ volatile boolean daemon;
+
+ /** The thread priority, 1 to 10. */
+ volatile int priority;
+
+ /** Native thread stack size. 0 = use default */
+ private long stacksize;
+
+ /** Was the thread stopped before it was started? */
+ Throwable stillborn;
+
+ /** The context classloader for this Thread. */
+ private ClassLoader contextClassLoader;
+ private boolean contextClassLoaderIsSystemClassLoader;
+
+ /** This thread's ID. */
+ private final long threadId;
+
+ /** The park blocker. See LockSupport. */
+ Object parkBlocker;
+
+ /** The next thread number to use. */
+ private static int numAnonymousThreadsCreated;
+
+ /** Used to generate the next thread ID to use. */
+ private static long totalThreadsCreated;
+
+ /** The default exception handler. */
+ private static UncaughtExceptionHandler defaultHandler;
+
+ /** Thread local storage. Package accessible for use by
+ * InheritableThreadLocal.
+ */
+ final ThreadLocalMap 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>
+ * <i>gname</i><code>)</code>, where <b><i>gname</i></b> is
+ * a newly generated name. Automatically generated names are of the
+ * form <code>"Thread-"+</code><i>n</i>, where <i>n</i> is an integer.
+ * <p>
+ * Threads created this way must have overridden their
+ * <code>run()</code> method to actually do anything. An example
+ * illustrating this method being used follows:
+ * <p><blockquote><pre>
+ * import java.lang.*;
+ *
+ * class plain01 implements Runnable {
+ * String name;
+ * plain01() {
+ * name = null;
+ * }
+ * plain01(String s) {
+ * name = s;
+ * }
+ * public void run() {
+ * if (name == null)
+ * System.out.println("A new thread created");
+ * else
+ * System.out.println("A new thread with name " + name +
+ * " created");
+ * }
+ * }
+ * class threadtest01 {
+ * public static void main(String args[] ) {
+ * int failed = 0 ;
+ *
+ * <b>Thread t1 = new Thread();</b>
+ * if (t1 != null)
+ * System.out.println("new Thread() succeed");
+ * else {
+ * System.out.println("new Thread() failed");
+ * failed++;
+ * }
+ * }
+ * }
+ * </pre></blockquote>
+ *
+ * @see java.lang.Thread#Thread(java.lang.ThreadGroup,
+ * java.lang.Runnable, java.lang.String)
+ */
+ public Thread()
+ {
+ this(null, (Runnable) null);
+ }
+
+ /**
+ * Allocates a new <code>Thread</code> object. This constructor has
+ * the same effect as <code>Thread(null, target,</code>
+ * <i>gname</i><code>)</code>, where <i>gname</i> is
+ * a newly generated name. Automatically generated names are of the
+ * form <code>"Thread-"+</code><i>n</i>, where <i>n</i> is an integer.
+ *
+ * @param target the object whose <code>run</code> method is called.
+ * @see java.lang.Thread#Thread(java.lang.ThreadGroup,
+ * java.lang.Runnable, java.lang.String)
+ */
+ public Thread(Runnable target)
+ {
+ this(null, target);
+ }
+
+ /**
+ * Allocates a new <code>Thread</code> object. This constructor has
+ * the same effect as <code>Thread(null, null, name)</code>.
+ *
+ * @param name the name of the new thread.
+ * @see java.lang.Thread#Thread(java.lang.ThreadGroup,
+ * java.lang.Runnable, java.lang.String)
+ */
+ public Thread(String name)
+ {
+ this(null, null, name, 0);
+ }
+
+ /**
+ * Allocates a new <code>Thread</code> object. This constructor has
+ * the same effect as <code>Thread(group, target,</code>
+ * <i>gname</i><code>)</code>, where <i>gname</i> is
+ * a newly generated name. Automatically generated names are of the
+ * form <code>"Thread-"+</code><i>n</i>, where <i>n</i> is an integer.
+ *
+ * @param group the group to put the Thread into
+ * @param target the Runnable object to execute
+ * @throws SecurityException if this thread cannot access <code>group</code>
+ * @throws IllegalThreadStateException if group is destroyed
+ * @see #Thread(ThreadGroup, Runnable, String)
+ */
+ public Thread(ThreadGroup group, Runnable target)
+ {
+ this(group, target, createAnonymousThreadName(), 0);
+ }
+
+ /**
+ * Allocates a new <code>Thread</code> object. This constructor has
+ * the same effect as <code>Thread(group, null, name)</code>
+ *
+ * @param group the group to put the Thread into
+ * @param name the name for the Thread
+ * @throws NullPointerException if name is null
+ * @throws SecurityException if this thread cannot access <code>group</code>
+ * @throws IllegalThreadStateException if group is destroyed
+ * @see #Thread(ThreadGroup, Runnable, String)
+ */
+ public Thread(ThreadGroup group, String name)
+ {
+ this(group, null, name, 0);
+ }
+
+ /**
+ * Allocates a new <code>Thread</code> object. This constructor has
+ * the same effect as <code>Thread(null, target, name)</code>.
+ *
+ * @param target the Runnable object to execute
+ * @param name the name for the Thread
+ * @throws NullPointerException if name is null
+ * @see #Thread(ThreadGroup, Runnable, String)
+ */
+ public Thread(Runnable target, String name)
+ {
+ this(null, target, name, 0);
+ }
+
+ /**
+ * Allocate a new Thread object, with the specified ThreadGroup and name, and
+ * using the specified Runnable object's <code>run()</code> method to
+ * execute. If the Runnable object is null, <code>this</code> (which is
+ * a Runnable) is used instead.
+ *
+ * <p>If the ThreadGroup is null, the security manager is checked. If a
+ * manager exists and returns a non-null object for
+ * <code>getThreadGroup</code>, that group is used; otherwise the group
+ * of the creating thread is used. Note that the security manager calls
+ * <code>checkAccess</code> if the ThreadGroup is not null.
+ *
+ * <p>The new Thread will inherit its creator's priority and daemon status.
+ * These can be changed with <code>setPriority</code> and
+ * <code>setDaemon</code>.
+ *
+ * @param group the group to put the Thread into
+ * @param target the Runnable object to execute
+ * @param name the name for the Thread
+ * @throws NullPointerException if name is null
+ * @throws SecurityException if this thread cannot access <code>group</code>
+ * @throws IllegalThreadStateException if group is destroyed
+ * @see Runnable#run()
+ * @see #run()
+ * @see #setDaemon(boolean)
+ * @see #setPriority(int)
+ * @see SecurityManager#checkAccess(ThreadGroup)
+ * @see ThreadGroup#checkAccess()
+ */
+ public Thread(ThreadGroup group, Runnable target, String name)
+ {
+ this(group, target, name, 0);
+ }
+
+ /**
+ * Allocate a new Thread object, as if by
+ * <code>Thread(group, null, name)</code>, and give it the specified stack
+ * size, in bytes. The stack size is <b>highly platform independent</b>,
+ * and the virtual machine is free to round up or down, or ignore it
+ * completely. A higher value might let you go longer before a
+ * <code>StackOverflowError</code>, while a lower value might let you go
+ * longer before an <code>OutOfMemoryError</code>. Or, it may do absolutely
+ * nothing! So be careful, and expect to need to tune this value if your
+ * virtual machine even supports it.
+ *
+ * @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)
+ {
+ // Bypass System.getSecurityManager, for bootstrap efficiency.
+ SecurityManager sm = SecurityManager.current;
+ Thread current = currentThread();
+ if (group == null)
+ {
+ if (sm != null)
+ group = sm.getThreadGroup();
+ if (group == null)
+ group = current.group;
+ }
+ if (sm != null)
+ sm.checkAccess(group);
+
+ this.group = group;
+ // Use toString hack to detect null.
+ this.name = name.toString();
+ this.runnable = target;
+ this.stacksize = size;
+ this.locals = new ThreadLocalMap();
+
+ synchronized (Thread.class)
+ {
+ this.threadId = ++totalThreadsCreated;
+ }
+
+ priority = current.priority;
+ daemon = current.daemon;
+ contextClassLoader = current.contextClassLoader;
+ contextClassLoaderIsSystemClassLoader =
+ current.contextClassLoaderIsSystemClassLoader;
+
+ group.addThread(this);
+ InheritableThreadLocal.newChildThread(this);
+ }
+
+ /**
+ * Used by the VM to create thread objects for threads started outside
+ * of Java. Note: caller is responsible for adding the thread to
+ * a group and InheritableThreadLocal.
+ * Note: This constructor should not call any methods that could result
+ * in a call to Thread.currentThread(), because that makes life harder
+ * for the VM.
+ *
+ * @param vmThread the native thread
+ * @param name the thread name or null to use the default naming scheme
+ * @param priority current priority
+ * @param daemon is the thread a background thread?
+ */
+ Thread(VMThread vmThread, String name, int priority, boolean daemon)
+ {
+ this.locals = new ThreadLocalMap();
+ this.vmThread = vmThread;
+ this.runnable = null;
+ if (name == null)
+ name = createAnonymousThreadName();
+ this.name = name;
+ this.priority = priority;
+ this.daemon = daemon;
+ // By default the context class loader is the system class loader,
+ // we set a flag to signal this because we don't want to call
+ // ClassLoader.getSystemClassLoader() at this point, because on
+ // VMs that lazily create the system class loader that might result
+ // in running user code (when a custom system class loader is specified)
+ // and that user code could call Thread.currentThread().
+ // ClassLoader.getSystemClassLoader() can also return null, if the system
+ // is currently in the process of constructing the system class loader
+ // (and, as above, the constructiong sequence calls Thread.currenThread()).
+ contextClassLoaderIsSystemClassLoader = true;
+ synchronized (Thread.class)
+ {
+ this.threadId = ++totalThreadsCreated;
+ }
+ }
+
+ /**
+ * Generate a name for an anonymous thread.
+ */
+ private static synchronized String createAnonymousThreadName()
+ {
+ return "Thread-" + ++numAnonymousThreadsCreated;
+ }
+
+ /**
+ * 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()
+ {
+ // Bypass System.getSecurityManager, for bootstrap efficiency.
+ SecurityManager sm = SecurityManager.current;
+ 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 int countStackFrames()
+ {
+ VMThread t = vmThread;
+ if (t == null || group == null)
+ throw new IllegalThreadStateException();
+
+ return t.countStackFrames();
+ }
+
+ /**
+ * Get the currently executing Thread. In the situation that the
+ * currently running thread was created by native code and doesn't
+ * have an associated Thread object yet, a new Thread object is
+ * constructed and associated with the native thread.
+ *
+ * @return the currently executing Thread
+ */
+ public static Thread currentThread()
+ {
+ return VMThread.currentThread();
+ }
+
+ /**
+ * 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()
+ {
+ 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 Throwable().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()
+ {
+ VMThread t = vmThread;
+ return t == null ? name : t.getName();
+ }
+
+ /**
+ * Get this Thread's priority.
+ *
+ * @return the Thread's priority
+ */
+ public final synchronized int getPriority()
+ {
+ VMThread t = vmThread;
+ return t == null ? priority : t.getPriority();
+ }
+
+ /**
+ * 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 boolean holdsLock(Object obj)
+ {
+ return VMThread.holdsLock(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 synchronized void interrupt()
+ {
+ checkAccess();
+ VMThread t = vmThread;
+ if (t != null)
+ t.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 VMThread.interrupted();
+ }
+
+ /**
+ * 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()
+ {
+ VMThread t = vmThread;
+ return t != null && t.isInterrupted();
+ }
+
+ /**
+ * 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 boolean isAlive()
+ {
+ return vmThread != null && group != null;
+ }
+
+ /**
+ * 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()
+ {
+ VMThread t = vmThread;
+ return t == null ? daemon : t.isDaemon();
+ }
+
+ /**
+ * 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
+ */
+ public final void join(long ms, int ns) throws InterruptedException
+ {
+ if (ms < 0 || ns < 0 || ns > 999999)
+ throw new IllegalArgumentException();
+
+ VMThread t = vmThread;
+ if (t != null)
+ t.join(ms, ns);
+ }
+
+ /**
+ * Resume this Thread. If the thread is not suspended, this method does
+ * nothing. To mirror suspend(), there may be a security check:
+ * <code>checkAccess</code>.
+ *
+ * @throws SecurityException if you cannot resume the Thread
+ * @see #checkAccess()
+ * @see #suspend()
+ * @deprecated pointless, since suspend is deprecated
+ */
+ public final synchronized void resume()
+ {
+ checkAccess();
+ VMThread t = vmThread;
+ if (t != null)
+ t.resume();
+ }
+
+ /**
+ * The method of Thread that will be run if there is no Runnable object
+ * associated with the Thread. Thread's implementation does nothing at all.
+ *
+ * @see #start()
+ * @see #Thread(ThreadGroup, Runnable, String)
+ */
+ public void run()
+ {
+ if (runnable != null)
+ runnable.run();
+ }
+
+ /**
+ * Set the daemon status of this Thread. If this is a daemon Thread, then
+ * the VM may exit even if it is still running. This may only be called
+ * before the Thread starts running. There may be a security check,
+ * <code>checkAccess</code>.
+ *
+ * @param daemon whether this should be a daemon thread or not
+ * @throws SecurityException if you cannot modify this Thread
+ * @throws IllegalThreadStateException if the Thread is active
+ * @see #isDaemon()
+ * @see #checkAccess()
+ */
+ public final synchronized void setDaemon(boolean daemon)
+ {
+ if (vmThread != null)
+ throw new IllegalThreadStateException();
+ checkAccess();
+ this.daemon = daemon;
+ }
+
+ /**
+ * Returns the context classloader of this Thread. The context
+ * classloader can be used by code that want to load classes depending
+ * on the current thread. Normally classes are loaded depending on
+ * the classloader of the current class. There may be a security check
+ * for <code>RuntimePermission("getClassLoader")</code> if the caller's
+ * class loader is not null or an ancestor of this thread's context class
+ * loader.
+ *
+ * @return the context class loader
+ * @throws SecurityException when permission is denied
+ * @see #setContextClassLoader(ClassLoader)
+ * @since 1.2
+ */
+ public synchronized ClassLoader getContextClassLoader()
+ {
+ ClassLoader loader = contextClassLoaderIsSystemClassLoader ?
+ ClassLoader.getSystemClassLoader() : contextClassLoader;
+ // Check if we may get the classloader
+ SecurityManager sm = SecurityManager.current;
+ if (loader != null && sm != null)
+ {
+ // Get the calling classloader
+ ClassLoader cl = VMStackWalker.getCallingClassLoader();
+ if (cl != null && !cl.isAncestorOf(loader))
+ sm.checkPermission(new RuntimePermission("getClassLoader"));
+ }
+ return loader;
+ }
+
+ /**
+ * Sets the context classloader for this Thread. When not explicitly set,
+ * the context classloader for a thread is the same as the context
+ * classloader of the thread that created this thread. The first thread has
+ * as context classloader the system classloader. There may be a security
+ * check for <code>RuntimePermission("setContextClassLoader")</code>.
+ *
+ * @param classloader the new context class loader
+ * @throws SecurityException when permission is denied
+ * @see #getContextClassLoader()
+ * @since 1.2
+ */
+ public synchronized void setContextClassLoader(ClassLoader classloader)
+ {
+ SecurityManager sm = SecurityManager.current;
+ if (sm != null)
+ sm.checkPermission(new RuntimePermission("setContextClassLoader"));
+ this.contextClassLoader = classloader;
+ contextClassLoaderIsSystemClassLoader = false;
+ }
+
+ /**
+ * Set this Thread's name. There may be a security check,
+ * <code>checkAccess</code>.
+ *
+ * @param name the new name for this Thread
+ * @throws NullPointerException if name is null
+ * @throws SecurityException if you cannot modify this Thread
+ */
+ public final synchronized void setName(String name)
+ {
+ checkAccess();
+ // The Class Libraries book says ``threadName cannot be null''. I
+ // take this to mean NullPointerException.
+ if (name == null)
+ throw new NullPointerException();
+ VMThread t = vmThread;
+ if (t != null)
+ t.setName(name);
+ else
+ this.name = name;
+ }
+
+ /**
+ * Yield to another thread. The Thread will not lose any locks it holds
+ * during this time. There are no guarantees which thread will be
+ * next to run, and it could even be this one, but most VMs will choose
+ * the highest priority thread that has been waiting longest.
+ */
+ public static void yield()
+ {
+ VMThread.yield();
+ }
+
+ /**
+ * Suspend the current Thread's execution for the specified amount of
+ * time. The Thread will not lose any locks it has during this time. There
+ * are no guarantees which thread will be next to run, but most VMs will
+ * choose the highest priority thread that has been waiting longest.
+ *
+ * @param ms the number of milliseconds to sleep, or 0 for forever
+ * @throws InterruptedException if the Thread is (or was) interrupted;
+ * it's <i>interrupted status</i> will be cleared
+ * @throws IllegalArgumentException if ms is negative
+ * @see #interrupt()
+ * @see #notify()
+ * @see #wait(long)
+ */
+ public static void sleep(long ms) throws InterruptedException
+ {
+ sleep(ms, 0);
+ }
+
+ /**
+ * Suspend the current Thread's execution for the specified amount of
+ * time. The Thread will not lose any locks it has during this time. There
+ * are no guarantees which thread will be next to run, but most VMs will
+ * choose the highest priority thread that has been waiting longest.
+ * <p>
+ * Note that 1,000,000 nanoseconds == 1 millisecond, but most VMs
+ * do not offer that fine a grain of timing resolution. When ms is
+ * zero and ns is non-zero the Thread will sleep for at least one
+ * milli second. 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 sleep, or 0 for forever
+ * @param ns the number of extra nanoseconds to sleep (0-999999)
+ * @throws InterruptedException if the Thread is (or was) interrupted;
+ * it's <i>interrupted status</i> will be cleared
+ * @throws IllegalArgumentException if ms or ns is negative
+ * or ns is larger than 999999.
+ * @see #interrupt()
+ * @see #notify()
+ * @see #wait(long, int)
+ */
+ public static void sleep(long ms, int ns) throws InterruptedException
+ {
+ // Check parameters
+ if (ms < 0 )
+ throw new IllegalArgumentException("Negative milliseconds: " + ms);
+
+ if (ns < 0 || ns > 999999)
+ throw new IllegalArgumentException("Nanoseconds ouf of range: " + ns);
+
+ // Really sleep
+ VMThread.sleep(ms, ns);
+ }
+
+ /**
+ * Start this Thread, calling the run() method of the Runnable this Thread
+ * was created with, or else the run() method of the Thread itself. This
+ * is the only way to start a new thread; calling run by yourself will just
+ * stay in the same thread. The virtual machine will remove the thread from
+ * its thread group when the run() method completes.
+ *
+ * @throws IllegalThreadStateException if the thread has already started
+ * @see #run()
+ */
+ public synchronized void start()
+ {
+ if (vmThread != null || group == null)
+ throw new IllegalThreadStateException();
+
+ VMThread.create(this, stacksize);
+ }
+
+ /**
+ * Cause this Thread to stop abnormally because of the throw of a ThreadDeath
+ * error. If you stop a Thread that has not yet started, it will stop
+ * immediately when it is actually started.
+ *
+ * <p>This is inherently unsafe, as it can interrupt synchronized blocks and
+ * leave data in bad states. Hence, there is a security check:
+ * <code>checkAccess(this)</code>, plus another one if the current thread
+ * is not this: <code>RuntimePermission("stopThread")</code>. If you must
+ * catch a ThreadDeath, be sure to rethrow it after you have cleaned up.
+ * ThreadDeath is the only exception which does not print a stack trace when
+ * the thread dies.
+ *
+ * @throws SecurityException if you cannot stop the Thread
+ * @see #interrupt()
+ * @see #checkAccess()
+ * @see #start()
+ * @see ThreadDeath
+ * @see ThreadGroup#uncaughtException(Thread, Throwable)
+ * @see SecurityManager#checkAccess(Thread)
+ * @see SecurityManager#checkPermission(Permission)
+ * @deprecated unsafe operation, try not to use
+ */
+ public final void stop()
+ {
+ stop(new ThreadDeath());
+ }
+
+ /**
+ * Cause this Thread to stop abnormally and throw the specified exception.
+ * If you stop a Thread that has not yet started, the stop is ignored
+ * (contrary to what the JDK documentation says).
+ * <b>WARNING</b>This bypasses Java security, and can throw a checked
+ * exception which the call stack is unprepared to handle. Do not abuse
+ * this power.
+ *
+ * <p>This is inherently unsafe, as it can interrupt synchronized blocks and
+ * leave data in bad states. Hence, there is a security check:
+ * <code>checkAccess(this)</code>, plus another one if the current thread
+ * is not this: <code>RuntimePermission("stopThread")</code>. If you must
+ * catch a ThreadDeath, be sure to rethrow it after you have cleaned up.
+ * ThreadDeath is the only exception which does not print a stack trace when
+ * the thread dies.
+ *
+ * @param t the Throwable to throw when the Thread dies
+ * @throws SecurityException if you cannot stop the Thread
+ * @throws NullPointerException in the calling thread, if t is null
+ * @see #interrupt()
+ * @see #checkAccess()
+ * @see #start()
+ * @see ThreadDeath
+ * @see ThreadGroup#uncaughtException(Thread, Throwable)
+ * @see SecurityManager#checkAccess(Thread)
+ * @see SecurityManager#checkPermission(Permission)
+ * @deprecated unsafe operation, try not to use
+ */
+ public final synchronized void stop(Throwable t)
+ {
+ if (t == null)
+ throw new NullPointerException();
+ // Bypass System.getSecurityManager, for bootstrap efficiency.
+ SecurityManager sm = SecurityManager.current;
+ if (sm != null)
+ {
+ sm.checkAccess(this);
+ if (this != currentThread() || !(t instanceof ThreadDeath))
+ sm.checkPermission(new RuntimePermission("stopThread"));
+ }
+ VMThread vt = vmThread;
+ if (vt != null)
+ vt.stop(t);
+ else
+ stillborn = t;
+ }
+
+ /**
+ * Suspend this Thread. It will not come back, ever, unless it is resumed.
+ *
+ * <p>This is inherently unsafe, as the suspended thread still holds locks,
+ * and can potentially deadlock your program. Hence, there is a security
+ * check: <code>checkAccess</code>.
+ *
+ * @throws SecurityException if you cannot suspend the Thread
+ * @see #checkAccess()
+ * @see #resume()
+ * @deprecated unsafe operation, try not to use
+ */
+ public final synchronized void suspend()
+ {
+ checkAccess();
+ VMThread t = vmThread;
+ if (t != null)
+ t.suspend();
+ }
+
+ /**
+ * Set this Thread's priority. There may be a security check,
+ * <code>checkAccess</code>, then the priority is set to the smaller of
+ * priority and the ThreadGroup maximum priority.
+ *
+ * @param priority the new priority for this Thread
+ * @throws IllegalArgumentException if priority exceeds MIN_PRIORITY or
+ * MAX_PRIORITY
+ * @throws SecurityException if you cannot modify this Thread
+ * @see #getPriority()
+ * @see #checkAccess()
+ * @see ThreadGroup#getMaxPriority()
+ * @see #MIN_PRIORITY
+ * @see #MAX_PRIORITY
+ */
+ public final synchronized void setPriority(int priority)
+ {
+ checkAccess();
+ if (priority < MIN_PRIORITY || priority > MAX_PRIORITY)
+ throw new IllegalArgumentException("Invalid thread priority value "
+ + priority + ".");
+ priority = Math.min(priority, group.getMaxPriority());
+ VMThread t = vmThread;
+ if (t != null)
+ t.setPriority(priority);
+ else
+ this.priority = priority;
+ }
+
+ /**
+ * Returns a string representation of this thread, including the
+ * thread's name, priority, and thread group.
+ *
+ * @return a human-readable String representing this Thread
+ */
+ public String toString()
+ {
+ return ("Thread[" + name + "," + priority + ","
+ + (group == null ? "" : group.getName()) + "]");
+ }
+
+ /**
+ * Clean up code, called by VMThread when thread dies.
+ */
+ synchronized void die()
+ {
+ group.removeThread(this);
+ vmThread = null;
+ locals.clear();
+ }
+
+ /**
+ * Returns the map used by ThreadLocal to store the thread local values.
+ */
+ static ThreadLocalMap getThreadLocals()
+ {
+ return currentThread().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#setUncaughtExceptionHandler(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);
+ }
+
+ /**
+ * <p>
+ * Represents the current state of a thread, according to the VM rather
+ * than the operating system. It can be one of the following:
+ * </p>
+ * <ul>
+ * <li>NEW -- The thread has just been created but is not yet running.</li>
+ * <li>RUNNABLE -- The thread is currently running or can be scheduled
+ * to run.</li>
+ * <li>BLOCKED -- The thread is blocked waiting on an I/O operation
+ * or to obtain a lock.</li>
+ * <li>WAITING -- The thread is waiting indefinitely for another thread
+ * to do something.</li>
+ * <li>TIMED_WAITING -- The thread is waiting for a specific amount of time
+ * for another thread to do something.</li>
+ * <li>TERMINATED -- The thread has exited.</li>
+ * </ul>
+ *
+ * @since 1.5
+ */
+ public enum State
+ {
+ BLOCKED, NEW, RUNNABLE, TERMINATED, TIMED_WAITING, WAITING;
+
+ /**
+ * For compatability with Sun's JDK
+ */
+ private static final long serialVersionUID = 605505746047245783L;
+ }
+
+
+ /**
+ * Returns the current state of the thread. This
+ * is designed for monitoring thread behaviour, rather
+ * than for synchronization control.
+ *
+ * @return the current thread state.
+ */
+ public State getState()
+ {
+ VMThread t = vmThread;
+ if (t != null)
+ return State.valueOf(t.getState());
+ if (group == null)
+ return State.TERMINATED;
+ return State.NEW;
+ }
+
+ /**
+ * <p>
+ * Returns a map of threads to stack traces for each
+ * live thread. The keys of the map are {@link Thread}
+ * objects, which map to arrays of {@link StackTraceElement}s.
+ * The results obtained from Calling this method are
+ * equivalent to calling {@link getStackTrace()} on each
+ * thread in succession. Threads may be executing while
+ * this takes place, and the results represent a snapshot
+ * of the thread at the time its {@link getStackTrace()}
+ * method is called.
+ * </p>
+ * <p>
+ * The stack trace information contains the methods called
+ * by the thread, with the most recent method forming the
+ * first element in the array. The array will be empty
+ * if the virtual machine can not obtain information on the
+ * thread.
+ * </p>
+ * <p>
+ * To execute this method, the current security manager
+ * (if one exists) must allow both the
+ * <code>"getStackTrace"</code> and
+ * <code>"modifyThreadGroup"</code> {@link RuntimePermission}s.
+ * </p>
+ *
+ * @return a map of threads to arrays of {@link StackTraceElement}s.
+ * @throws SecurityException if a security manager exists, and
+ * prevents either or both the runtime
+ * permissions specified above.
+ * @since 1.5
+ * @see #getStackTrace()
+ */
+ public static Map<Thread, StackTraceElement[]> getAllStackTraces()
+ {
+ ThreadGroup group = currentThread().group;
+ while (group.getParent() != null)
+ group = group.getParent();
+ int arraySize = group.activeCount();
+ Thread[] threadList = new Thread[arraySize];
+ int filled = group.enumerate(threadList);
+ while (filled == arraySize)
+ {
+ arraySize *= 2;
+ threadList = new Thread[arraySize];
+ filled = group.enumerate(threadList);
+ }
+ Map traces = new HashMap();
+ for (int a = 0; a < filled; ++a)
+ traces.put(threadList[a],
+ threadList[a].getStackTrace());
+ return traces;
+ }
+
+ /**
+ * <p>
+ * Returns an array of {@link StackTraceElement}s
+ * representing the current stack trace of this thread.
+ * The first element of the array is the most recent
+ * method called, and represents the top of the stack.
+ * The elements continue in this order, with the last
+ * element representing the bottom of the stack.
+ * </p>
+ * <p>
+ * A zero element array is returned for threads which
+ * have not yet started (and thus have not yet executed
+ * any methods) or for those which have terminated.
+ * Where the virtual machine can not obtain a trace for
+ * the thread, an empty array is also returned. The
+ * virtual machine may also omit some methods from the
+ * trace in non-zero arrays.
+ * </p>
+ * <p>
+ * To execute this method, the current security manager
+ * (if one exists) must allow both the
+ * <code>"getStackTrace"</code> and
+ * <code>"modifyThreadGroup"</code> {@link RuntimePermission}s.
+ * </p>
+ *
+ * @return a stack trace for this thread.
+ * @throws SecurityException if a security manager exists, and
+ * prevents the use of the
+ * <code>"getStackTrace"</code>
+ * permission.
+ * @since 1.5
+ * @see #getAllStackTraces()
+ */
+ public StackTraceElement[] getStackTrace()
+ {
+ SecurityManager sm = SecurityManager.current; // Be thread-safe.
+ if (sm != null)
+ sm.checkPermission(new RuntimePermission("getStackTrace"));
+ ThreadMXBean bean = ManagementFactory.getThreadMXBean();
+ ThreadInfo info = bean.getThreadInfo(threadId, Integer.MAX_VALUE);
+ return info.getStackTrace();
+ }
+
+}