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Diffstat (limited to 'libjava/classpath/java/lang/Thread.java')
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diff --git a/libjava/classpath/java/lang/Thread.java b/libjava/classpath/java/lang/Thread.java new file mode 100644 index 00000000000..37ca630b4ed --- /dev/null +++ b/libjava/classpath/java/lang/Thread.java @@ -0,0 +1,999 @@ +/* Thread -- an independent thread of executable code + Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004 + 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 java.util.Map; +import java.util.WeakHashMap; + +/* 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) + * @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; + + /** The next thread number to use. */ + private static int numAnonymousThreadsCreated; + + /** Thread local storage. Package accessible for use by + * InheritableThreadLocal. + */ + WeakHashMap locals; + + /** + * 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, "Thread-" + ++numAnonymousThreadsCreated, 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; + } + else 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; + + priority = current.priority; + daemon = current.daemon; + contextClassLoader = current.contextClassLoader; + + 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. + * + * @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.vmThread = vmThread; + this.runnable = null; + if (name == null) + name = "Thread-" + ++numAnonymousThreadsCreated; + this.name = name; + this.priority = priority; + this.daemon = daemon; + this.contextClassLoader = ClassLoader.getSystemClassLoader(); + } + + /** + * 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. + */ + 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() + { + // Bypass System.getSecurityManager, for bootstrap efficiency. + SecurityManager sm = SecurityManager.current; + if (sm != null) + // XXX Don't check this if the caller's class loader is an ancestor. + sm.checkPermission(new RuntimePermission("getClassLoader")); + return contextClassLoader; + } + + /** + * 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; + } + + /** + * 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. + * @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() + */ + 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 + * @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() + */ + public static void sleep(long ms, int ns) throws InterruptedException + { + + // Check parameters + if (ms < 0 || ns < 0 || ns > 999999) + throw new IllegalArgumentException(); + + // 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()) + 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 = null; + } + + /** + * Returns the map used by ThreadLocal to store the thread local values. + */ + static Map getThreadLocals() + { + Thread thread = currentThread(); + Map locals = thread.locals; + if (locals == null) + { + locals = thread.locals = new WeakHashMap(); + } + return locals; + } +} |