| GNU Classpath (0.95) | |
| Frames | No Frames |
1: /* Thread -- an independent thread of executable code 2: Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 3: Free Software Foundation 4: 5: This file is part of GNU Classpath. 6: 7: GNU Classpath is free software; you can redistribute it and/or modify 8: it under the terms of the GNU General Public License as published by 9: the Free Software Foundation; either version 2, or (at your option) 10: any later version. 11: 12: GNU Classpath is distributed in the hope that it will be useful, but 13: WITHOUT ANY WARRANTY; without even the implied warranty of 14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15: General Public License for more details. 16: 17: You should have received a copy of the GNU General Public License 18: along with GNU Classpath; see the file COPYING. If not, write to the 19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 20: 02110-1301 USA. 21: 22: Linking this library statically or dynamically with other modules is 23: making a combined work based on this library. Thus, the terms and 24: conditions of the GNU General Public License cover the whole 25: combination. 26: 27: As a special exception, the copyright holders of this library give you 28: permission to link this library with independent modules to produce an 29: executable, regardless of the license terms of these independent 30: modules, and to copy and distribute the resulting executable under 31: terms of your choice, provided that you also meet, for each linked 32: independent module, the terms and conditions of the license of that 33: module. An independent module is a module which is not derived from 34: or based on this library. If you modify this library, you may extend 35: this exception to your version of the library, but you are not 36: obligated to do so. If you do not wish to do so, delete this 37: exception statement from your version. */ 38: 39: package java.lang; 40: 41: import gnu.classpath.VMStackWalker; 42: import gnu.java.util.WeakIdentityHashMap; 43: 44: import java.lang.management.ManagementFactory; 45: import java.lang.management.ThreadInfo; 46: import java.lang.management.ThreadMXBean; 47: 48: import java.security.Permission; 49: 50: import java.util.HashMap; 51: import java.util.Map; 52: 53: /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 54: * "The Java Language Specification", ISBN 0-201-63451-1 55: * plus online API docs for JDK 1.2 beta from http://www.javasoft.com. 56: * Status: Believed complete to version 1.4, with caveats. We do not 57: * implement the deprecated (and dangerous) stop, suspend, and resume 58: * methods. Security implementation is not complete. 59: */ 60: 61: /** 62: * Thread represents a single thread of execution in the VM. When an 63: * application VM starts up, it creates a non-daemon Thread which calls the 64: * main() method of a particular class. There may be other Threads running, 65: * such as the garbage collection thread. 66: * 67: * <p>Threads have names to identify them. These names are not necessarily 68: * unique. Every Thread has a priority, as well, which tells the VM which 69: * Threads should get more running time. New threads inherit the priority 70: * and daemon status of the parent thread, by default. 71: * 72: * <p>There are two methods of creating a Thread: you may subclass Thread and 73: * implement the <code>run()</code> method, at which point you may start the 74: * Thread by calling its <code>start()</code> method, or you may implement 75: * <code>Runnable</code> in the class you want to use and then call new 76: * <code>Thread(your_obj).start()</code>. 77: * 78: * <p>The virtual machine runs until all non-daemon threads have died (either 79: * by returning from the run() method as invoked by start(), or by throwing 80: * an uncaught exception); or until <code>System.exit</code> is called with 81: * adequate permissions. 82: * 83: * <p>It is unclear at what point a Thread should be added to a ThreadGroup, 84: * and at what point it should be removed. Should it be inserted when it 85: * starts, or when it is created? Should it be removed when it is suspended 86: * or interrupted? The only thing that is clear is that the Thread should be 87: * removed when it is stopped. 88: * 89: * @author Tom Tromey 90: * @author John Keiser 91: * @author Eric Blake (ebb9@email.byu.edu) 92: * @author Andrew John Hughes (gnu_andrew@member.fsf.org) 93: * @see Runnable 94: * @see Runtime#exit(int) 95: * @see #run() 96: * @see #start() 97: * @see ThreadLocal 98: * @since 1.0 99: * @status updated to 1.4 100: */ 101: public class Thread implements Runnable 102: { 103: /** The minimum priority for a Thread. */ 104: public static final int MIN_PRIORITY = 1; 105: 106: /** The priority a Thread gets by default. */ 107: public static final int NORM_PRIORITY = 5; 108: 109: /** The maximum priority for a Thread. */ 110: public static final int MAX_PRIORITY = 10; 111: 112: /** The underlying VM thread, only set when the thread is actually running. 113: */ 114: volatile VMThread vmThread; 115: 116: /** 117: * The group this thread belongs to. This is set to null by 118: * ThreadGroup.removeThread when the thread dies. 119: */ 120: volatile ThreadGroup group; 121: 122: /** The object to run(), null if this is the target. */ 123: final Runnable runnable; 124: 125: /** The thread name, non-null. */ 126: volatile String name; 127: 128: /** Whether the thread is a daemon. */ 129: volatile boolean daemon; 130: 131: /** The thread priority, 1 to 10. */ 132: volatile int priority; 133: 134: /** Native thread stack size. 0 = use default */ 135: private long stacksize; 136: 137: /** Was the thread stopped before it was started? */ 138: Throwable stillborn; 139: 140: /** The context classloader for this Thread. */ 141: private ClassLoader contextClassLoader; 142: private boolean contextClassLoaderIsSystemClassLoader; 143: 144: /** This thread's ID. */ 145: private final long threadId; 146: 147: /** The park blocker. See LockSupport. */ 148: Object parkBlocker; 149: 150: /** The next thread number to use. */ 151: private static int numAnonymousThreadsCreated; 152: 153: /** Used to generate the next thread ID to use. */ 154: private static long totalThreadsCreated; 155: 156: /** The default exception handler. */ 157: private static UncaughtExceptionHandler defaultHandler; 158: 159: /** Thread local storage. Package accessible for use by 160: * InheritableThreadLocal. 161: */ 162: WeakIdentityHashMap locals; 163: 164: /** The uncaught exception handler. */ 165: UncaughtExceptionHandler exceptionHandler; 166: 167: /** 168: * Allocates a new <code>Thread</code> object. This constructor has 169: * the same effect as <code>Thread(null, null,</code> 170: * <i>gname</i><code>)</code>, where <b><i>gname</i></b> is 171: * a newly generated name. Automatically generated names are of the 172: * form <code>"Thread-"+</code><i>n</i>, where <i>n</i> is an integer. 173: * <p> 174: * Threads created this way must have overridden their 175: * <code>run()</code> method to actually do anything. An example 176: * illustrating this method being used follows: 177: * <p><blockquote><pre> 178: * import java.lang.*; 179: * 180: * class plain01 implements Runnable { 181: * String name; 182: * plain01() { 183: * name = null; 184: * } 185: * plain01(String s) { 186: * name = s; 187: * } 188: * public void run() { 189: * if (name == null) 190: * System.out.println("A new thread created"); 191: * else 192: * System.out.println("A new thread with name " + name + 193: * " created"); 194: * } 195: * } 196: * class threadtest01 { 197: * public static void main(String args[] ) { 198: * int failed = 0 ; 199: * 200: * <b>Thread t1 = new Thread();</b> 201: * if (t1 != null) 202: * System.out.println("new Thread() succeed"); 203: * else { 204: * System.out.println("new Thread() failed"); 205: * failed++; 206: * } 207: * } 208: * } 209: * </pre></blockquote> 210: * 211: * @see java.lang.Thread#Thread(java.lang.ThreadGroup, 212: * java.lang.Runnable, java.lang.String) 213: */ 214: public Thread() 215: { 216: this(null, (Runnable) null); 217: } 218: 219: /** 220: * Allocates a new <code>Thread</code> object. This constructor has 221: * the same effect as <code>Thread(null, target,</code> 222: * <i>gname</i><code>)</code>, where <i>gname</i> is 223: * a newly generated name. Automatically generated names are of the 224: * form <code>"Thread-"+</code><i>n</i>, where <i>n</i> is an integer. 225: * 226: * @param target the object whose <code>run</code> method is called. 227: * @see java.lang.Thread#Thread(java.lang.ThreadGroup, 228: * java.lang.Runnable, java.lang.String) 229: */ 230: public Thread(Runnable target) 231: { 232: this(null, target); 233: } 234: 235: /** 236: * Allocates a new <code>Thread</code> object. This constructor has 237: * the same effect as <code>Thread(null, null, name)</code>. 238: * 239: * @param name the name of the new thread. 240: * @see java.lang.Thread#Thread(java.lang.ThreadGroup, 241: * java.lang.Runnable, java.lang.String) 242: */ 243: public Thread(String name) 244: { 245: this(null, null, name, 0); 246: } 247: 248: /** 249: * Allocates a new <code>Thread</code> object. This constructor has 250: * the same effect as <code>Thread(group, target,</code> 251: * <i>gname</i><code>)</code>, where <i>gname</i> is 252: * a newly generated name. Automatically generated names are of the 253: * form <code>"Thread-"+</code><i>n</i>, where <i>n</i> is an integer. 254: * 255: * @param group the group to put the Thread into 256: * @param target the Runnable object to execute 257: * @throws SecurityException if this thread cannot access <code>group</code> 258: * @throws IllegalThreadStateException if group is destroyed 259: * @see #Thread(ThreadGroup, Runnable, String) 260: */ 261: public Thread(ThreadGroup group, Runnable target) 262: { 263: this(group, target, createAnonymousThreadName(), 0); 264: } 265: 266: /** 267: * Allocates a new <code>Thread</code> object. This constructor has 268: * the same effect as <code>Thread(group, null, name)</code> 269: * 270: * @param group the group to put the Thread into 271: * @param name the name for the Thread 272: * @throws NullPointerException if name is null 273: * @throws SecurityException if this thread cannot access <code>group</code> 274: * @throws IllegalThreadStateException if group is destroyed 275: * @see #Thread(ThreadGroup, Runnable, String) 276: */ 277: public Thread(ThreadGroup group, String name) 278: { 279: this(group, null, name, 0); 280: } 281: 282: /** 283: * Allocates a new <code>Thread</code> object. This constructor has 284: * the same effect as <code>Thread(null, target, name)</code>. 285: * 286: * @param target the Runnable object to execute 287: * @param name the name for the Thread 288: * @throws NullPointerException if name is null 289: * @see #Thread(ThreadGroup, Runnable, String) 290: */ 291: public Thread(Runnable target, String name) 292: { 293: this(null, target, name, 0); 294: } 295: 296: /** 297: * Allocate a new Thread object, with the specified ThreadGroup and name, and 298: * using the specified Runnable object's <code>run()</code> method to 299: * execute. If the Runnable object is null, <code>this</code> (which is 300: * a Runnable) is used instead. 301: * 302: * <p>If the ThreadGroup is null, the security manager is checked. If a 303: * manager exists and returns a non-null object for 304: * <code>getThreadGroup</code>, that group is used; otherwise the group 305: * of the creating thread is used. Note that the security manager calls 306: * <code>checkAccess</code> if the ThreadGroup is not null. 307: * 308: * <p>The new Thread will inherit its creator's priority and daemon status. 309: * These can be changed with <code>setPriority</code> and 310: * <code>setDaemon</code>. 311: * 312: * @param group the group to put the Thread into 313: * @param target the Runnable object to execute 314: * @param name the name for the Thread 315: * @throws NullPointerException if name is null 316: * @throws SecurityException if this thread cannot access <code>group</code> 317: * @throws IllegalThreadStateException if group is destroyed 318: * @see Runnable#run() 319: * @see #run() 320: * @see #setDaemon(boolean) 321: * @see #setPriority(int) 322: * @see SecurityManager#checkAccess(ThreadGroup) 323: * @see ThreadGroup#checkAccess() 324: */ 325: public Thread(ThreadGroup group, Runnable target, String name) 326: { 327: this(group, target, name, 0); 328: } 329: 330: /** 331: * Allocate a new Thread object, as if by 332: * <code>Thread(group, null, name)</code>, and give it the specified stack 333: * size, in bytes. The stack size is <b>highly platform independent</b>, 334: * and the virtual machine is free to round up or down, or ignore it 335: * completely. A higher value might let you go longer before a 336: * <code>StackOverflowError</code>, while a lower value might let you go 337: * longer before an <code>OutOfMemoryError</code>. Or, it may do absolutely 338: * nothing! So be careful, and expect to need to tune this value if your 339: * virtual machine even supports it. 340: * 341: * @param group the group to put the Thread into 342: * @param target the Runnable object to execute 343: * @param name the name for the Thread 344: * @param size the stack size, in bytes; 0 to be ignored 345: * @throws NullPointerException if name is null 346: * @throws SecurityException if this thread cannot access <code>group</code> 347: * @throws IllegalThreadStateException if group is destroyed 348: * @since 1.4 349: */ 350: public Thread(ThreadGroup group, Runnable target, String name, long size) 351: { 352: // Bypass System.getSecurityManager, for bootstrap efficiency. 353: SecurityManager sm = SecurityManager.current; 354: Thread current = currentThread(); 355: if (group == null) 356: { 357: if (sm != null) 358: group = sm.getThreadGroup(); 359: if (group == null) 360: group = current.group; 361: } 362: if (sm != null) 363: sm.checkAccess(group); 364: 365: this.group = group; 366: // Use toString hack to detect null. 367: this.name = name.toString(); 368: this.runnable = target; 369: this.stacksize = size; 370: 371: synchronized (Thread.class) 372: { 373: this.threadId = ++totalThreadsCreated; 374: } 375: 376: priority = current.priority; 377: daemon = current.daemon; 378: contextClassLoader = current.contextClassLoader; 379: contextClassLoaderIsSystemClassLoader = 380: current.contextClassLoaderIsSystemClassLoader; 381: 382: group.addThread(this); 383: InheritableThreadLocal.newChildThread(this); 384: } 385: 386: /** 387: * Used by the VM to create thread objects for threads started outside 388: * of Java. Note: caller is responsible for adding the thread to 389: * a group and InheritableThreadLocal. 390: * Note: This constructor should not call any methods that could result 391: * in a call to Thread.currentThread(), because that makes life harder 392: * for the VM. 393: * 394: * @param vmThread the native thread 395: * @param name the thread name or null to use the default naming scheme 396: * @param priority current priority 397: * @param daemon is the thread a background thread? 398: */ 399: Thread(VMThread vmThread, String name, int priority, boolean daemon) 400: { 401: this.vmThread = vmThread; 402: this.runnable = null; 403: if (name == null) 404: name = createAnonymousThreadName(); 405: this.name = name; 406: this.priority = priority; 407: this.daemon = daemon; 408: // By default the context class loader is the system class loader, 409: // we set a flag to signal this because we don't want to call 410: // ClassLoader.getSystemClassLoader() at this point, because on 411: // VMs that lazily create the system class loader that might result 412: // in running user code (when a custom system class loader is specified) 413: // and that user code could call Thread.currentThread(). 414: // ClassLoader.getSystemClassLoader() can also return null, if the system 415: // is currently in the process of constructing the system class loader 416: // (and, as above, the constructiong sequence calls Thread.currenThread()). 417: contextClassLoaderIsSystemClassLoader = true; 418: synchronized (Thread.class) 419: { 420: this.threadId = ++totalThreadsCreated; 421: } 422: } 423: 424: /** 425: * Generate a name for an anonymous thread. 426: */ 427: private static synchronized String createAnonymousThreadName() 428: { 429: return "Thread-" + ++numAnonymousThreadsCreated; 430: } 431: 432: /** 433: * Get the number of active threads in the current Thread's ThreadGroup. 434: * This implementation calls 435: * <code>currentThread().getThreadGroup().activeCount()</code>. 436: * 437: * @return the number of active threads in the current ThreadGroup 438: * @see ThreadGroup#activeCount() 439: */ 440: public static int activeCount() 441: { 442: return currentThread().group.activeCount(); 443: } 444: 445: /** 446: * Check whether the current Thread is allowed to modify this Thread. This 447: * passes the check on to <code>SecurityManager.checkAccess(this)</code>. 448: * 449: * @throws SecurityException if the current Thread cannot modify this Thread 450: * @see SecurityManager#checkAccess(Thread) 451: */ 452: public final void checkAccess() 453: { 454: // Bypass System.getSecurityManager, for bootstrap efficiency. 455: SecurityManager sm = SecurityManager.current; 456: if (sm != null) 457: sm.checkAccess(this); 458: } 459: 460: /** 461: * Count the number of stack frames in this Thread. The Thread in question 462: * must be suspended when this occurs. 463: * 464: * @return the number of stack frames in this Thread 465: * @throws IllegalThreadStateException if this Thread is not suspended 466: * @deprecated pointless, since suspend is deprecated 467: */ 468: public int countStackFrames() 469: { 470: VMThread t = vmThread; 471: if (t == null || group == null) 472: throw new IllegalThreadStateException(); 473: 474: return t.countStackFrames(); 475: } 476: 477: /** 478: * Get the currently executing Thread. In the situation that the 479: * currently running thread was created by native code and doesn't 480: * have an associated Thread object yet, a new Thread object is 481: * constructed and associated with the native thread. 482: * 483: * @return the currently executing Thread 484: */ 485: public static Thread currentThread() 486: { 487: return VMThread.currentThread(); 488: } 489: 490: /** 491: * Originally intended to destroy this thread, this method was never 492: * implemented by Sun, and is hence a no-op. 493: * 494: * @deprecated This method was originally intended to simply destroy 495: * the thread without performing any form of cleanup operation. 496: * However, it was never implemented. It is now deprecated 497: * for the same reason as <code>suspend()</code>, 498: * <code>stop()</code> and <code>resume()</code>; namely, 499: * it is prone to deadlocks. If a thread is destroyed while 500: * it still maintains a lock on a resource, then this resource 501: * will remain locked and any attempts by other threads to 502: * access the resource will result in a deadlock. Thus, even 503: * an implemented version of this method would be still be 504: * deprecated, due to its unsafe nature. 505: * @throws NoSuchMethodError as this method was never implemented. 506: */ 507: public void destroy() 508: { 509: throw new NoSuchMethodError(); 510: } 511: 512: /** 513: * Print a stack trace of the current thread to stderr using the same 514: * format as Throwable's printStackTrace() method. 515: * 516: * @see Throwable#printStackTrace() 517: */ 518: public static void dumpStack() 519: { 520: new Throwable().printStackTrace(); 521: } 522: 523: /** 524: * Copy every active thread in the current Thread's ThreadGroup into the 525: * array. Extra threads are silently ignored. This implementation calls 526: * <code>getThreadGroup().enumerate(array)</code>, which may have a 527: * security check, <code>checkAccess(group)</code>. 528: * 529: * @param array the array to place the Threads into 530: * @return the number of Threads placed into the array 531: * @throws NullPointerException if array is null 532: * @throws SecurityException if you cannot access the ThreadGroup 533: * @see ThreadGroup#enumerate(Thread[]) 534: * @see #activeCount() 535: * @see SecurityManager#checkAccess(ThreadGroup) 536: */ 537: public static int enumerate(Thread[] array) 538: { 539: return currentThread().group.enumerate(array); 540: } 541: 542: /** 543: * Get this Thread's name. 544: * 545: * @return this Thread's name 546: */ 547: public final String getName() 548: { 549: VMThread t = vmThread; 550: return t == null ? name : t.getName(); 551: } 552: 553: /** 554: * Get this Thread's priority. 555: * 556: * @return the Thread's priority 557: */ 558: public final synchronized int getPriority() 559: { 560: VMThread t = vmThread; 561: return t == null ? priority : t.getPriority(); 562: } 563: 564: /** 565: * Get the ThreadGroup this Thread belongs to. If the thread has died, this 566: * returns null. 567: * 568: * @return this Thread's ThreadGroup 569: */ 570: public final ThreadGroup getThreadGroup() 571: { 572: return group; 573: } 574: 575: /** 576: * Checks whether the current thread holds the monitor on a given object. 577: * This allows you to do <code>assert Thread.holdsLock(obj)</code>. 578: * 579: * @param obj the object to test lock ownership on. 580: * @return true if the current thread is currently synchronized on obj 581: * @throws NullPointerException if obj is null 582: * @since 1.4 583: */ 584: public static boolean holdsLock(Object obj) 585: { 586: return VMThread.holdsLock(obj); 587: } 588: 589: /** 590: * Interrupt this Thread. First, there is a security check, 591: * <code>checkAccess</code>. Then, depending on the current state of the 592: * thread, various actions take place: 593: * 594: * <p>If the thread is waiting because of {@link #wait()}, 595: * {@link #sleep(long)}, or {@link #join()}, its <i>interrupt status</i> 596: * will be cleared, and an InterruptedException will be thrown. Notice that 597: * this case is only possible if an external thread called interrupt(). 598: * 599: * <p>If the thread is blocked in an interruptible I/O operation, in 600: * {@link java.nio.channels.InterruptibleChannel}, the <i>interrupt 601: * status</i> will be set, and ClosedByInterruptException will be thrown. 602: * 603: * <p>If the thread is blocked on a {@link java.nio.channels.Selector}, the 604: * <i>interrupt status</i> will be set, and the selection will return, with 605: * a possible non-zero value, as though by the wakeup() method. 606: * 607: * <p>Otherwise, the interrupt status will be set. 608: * 609: * @throws SecurityException if you cannot modify this Thread 610: */ 611: public synchronized void interrupt() 612: { 613: checkAccess(); 614: VMThread t = vmThread; 615: if (t != null) 616: t.interrupt(); 617: } 618: 619: /** 620: * Determine whether the current Thread has been interrupted, and clear 621: * the <i>interrupted status</i> in the process. 622: * 623: * @return whether the current Thread has been interrupted 624: * @see #isInterrupted() 625: */ 626: public static boolean interrupted() 627: { 628: return VMThread.interrupted(); 629: } 630: 631: /** 632: * Determine whether the given Thread has been interrupted, but leave 633: * the <i>interrupted status</i> alone in the process. 634: * 635: * @return whether the Thread has been interrupted 636: * @see #interrupted() 637: */ 638: public boolean isInterrupted() 639: { 640: VMThread t = vmThread; 641: return t != null && t.isInterrupted(); 642: } 643: 644: /** 645: * Determine whether this Thread is alive. A thread which is alive has 646: * started and not yet died. 647: * 648: * @return whether this Thread is alive 649: */ 650: public final boolean isAlive() 651: { 652: return vmThread != null && group != null; 653: } 654: 655: /** 656: * Tell whether this is a daemon Thread or not. 657: * 658: * @return whether this is a daemon Thread or not 659: * @see #setDaemon(boolean) 660: */ 661: public final boolean isDaemon() 662: { 663: VMThread t = vmThread; 664: return t == null ? daemon : t.isDaemon(); 665: } 666: 667: /** 668: * Wait forever for the Thread in question to die. 669: * 670: * @throws InterruptedException if the Thread is interrupted; it's 671: * <i>interrupted status</i> will be cleared 672: */ 673: public final void join() throws InterruptedException 674: { 675: join(0, 0); 676: } 677: 678: /** 679: * Wait the specified amount of time for the Thread in question to die. 680: * 681: * @param ms the number of milliseconds to wait, or 0 for forever 682: * @throws InterruptedException if the Thread is interrupted; it's 683: * <i>interrupted status</i> will be cleared 684: */ 685: public final void join(long ms) throws InterruptedException 686: { 687: join(ms, 0); 688: } 689: 690: /** 691: * Wait the specified amount of time for the Thread in question to die. 692: * 693: * <p>Note that 1,000,000 nanoseconds == 1 millisecond, but most VMs do 694: * not offer that fine a grain of timing resolution. Besides, there is 695: * no guarantee that this thread can start up immediately when time expires, 696: * because some other thread may be active. So don't expect real-time 697: * performance. 698: * 699: * @param ms the number of milliseconds to wait, or 0 for forever 700: * @param ns the number of extra nanoseconds to sleep (0-999999) 701: * @throws InterruptedException if the Thread is interrupted; it's 702: * <i>interrupted status</i> will be cleared 703: * @throws IllegalArgumentException if ns is invalid 704: */ 705: public final void join(long ms, int ns) throws InterruptedException 706: { 707: if (ms < 0 || ns < 0 || ns > 999999) 708: throw new IllegalArgumentException(); 709: 710: VMThread t = vmThread; 711: if (t != null) 712: t.join(ms, ns); 713: } 714: 715: /** 716: * Resume this Thread. If the thread is not suspended, this method does 717: * nothing. To mirror suspend(), there may be a security check: 718: * <code>checkAccess</code>. 719: * 720: * @throws SecurityException if you cannot resume the Thread 721: * @see #checkAccess() 722: * @see #suspend() 723: * @deprecated pointless, since suspend is deprecated 724: */ 725: public final synchronized void resume() 726: { 727: checkAccess(); 728: VMThread t = vmThread; 729: if (t != null) 730: t.resume(); 731: } 732: 733: /** 734: * The method of Thread that will be run if there is no Runnable object 735: * associated with the Thread. Thread's implementation does nothing at all. 736: * 737: * @see #start() 738: * @see #Thread(ThreadGroup, Runnable, String) 739: */ 740: public void run() 741: { 742: if (runnable != null) 743: runnable.run(); 744: } 745: 746: /** 747: * Set the daemon status of this Thread. If this is a daemon Thread, then 748: * the VM may exit even if it is still running. This may only be called 749: * before the Thread starts running. There may be a security check, 750: * <code>checkAccess</code>. 751: * 752: * @param daemon whether this should be a daemon thread or not 753: * @throws SecurityException if you cannot modify this Thread 754: * @throws IllegalThreadStateException if the Thread is active 755: * @see #isDaemon() 756: * @see #checkAccess() 757: */ 758: public final synchronized void setDaemon(boolean daemon) 759: { 760: if (vmThread != null) 761: throw new IllegalThreadStateException(); 762: checkAccess(); 763: this.daemon = daemon; 764: } 765: 766: /** 767: * Returns the context classloader of this Thread. The context 768: * classloader can be used by code that want to load classes depending 769: * on the current thread. Normally classes are loaded depending on 770: * the classloader of the current class. There may be a security check 771: * for <code>RuntimePermission("getClassLoader")</code> if the caller's 772: * class loader is not null or an ancestor of this thread's context class 773: * loader. 774: * 775: * @return the context class loader 776: * @throws SecurityException when permission is denied 777: * @see #setContextClassLoader(ClassLoader) 778: * @since 1.2 779: */ 780: public synchronized ClassLoader getContextClassLoader() 781: { 782: ClassLoader loader = contextClassLoaderIsSystemClassLoader ? 783: ClassLoader.getSystemClassLoader() : contextClassLoader; 784: // Check if we may get the classloader 785: SecurityManager sm = SecurityManager.current; 786: if (loader != null && sm != null) 787: { 788: // Get the calling classloader 789: ClassLoader cl = VMStackWalker.getCallingClassLoader(); 790: if (cl != null && !cl.isAncestorOf(loader)) 791: sm.checkPermission(new RuntimePermission("getClassLoader")); 792: } 793: return loader; 794: } 795: 796: /** 797: * Sets the context classloader for this Thread. When not explicitly set, 798: * the context classloader for a thread is the same as the context 799: * classloader of the thread that created this thread. The first thread has 800: * as context classloader the system classloader. There may be a security 801: * check for <code>RuntimePermission("setContextClassLoader")</code>. 802: * 803: * @param classloader the new context class loader 804: * @throws SecurityException when permission is denied 805: * @see #getContextClassLoader() 806: * @since 1.2 807: */ 808: public synchronized void setContextClassLoader(ClassLoader classloader) 809: { 810: SecurityManager sm = SecurityManager.current; 811: if (sm != null) 812: sm.checkPermission(new RuntimePermission("setContextClassLoader")); 813: this.contextClassLoader = classloader; 814: contextClassLoaderIsSystemClassLoader = false; 815: } 816: 817: /** 818: * Set this Thread's name. There may be a security check, 819: * <code>checkAccess</code>. 820: * 821: * @param name the new name for this Thread 822: * @throws NullPointerException if name is null 823: * @throws SecurityException if you cannot modify this Thread 824: */ 825: public final synchronized void setName(String name) 826: { 827: checkAccess(); 828: // The Class Libraries book says ``threadName cannot be null''. I 829: // take this to mean NullPointerException. 830: if (name == null) 831: throw new NullPointerException(); 832: VMThread t = vmThread; 833: if (t != null) 834: t.setName(name); 835: else 836: this.name = name; 837: } 838: 839: /** 840: * Yield to another thread. The Thread will not lose any locks it holds 841: * during this time. There are no guarantees which thread will be 842: * next to run, and it could even be this one, but most VMs will choose 843: * the highest priority thread that has been waiting longest. 844: */ 845: public static void yield() 846: { 847: VMThread.yield(); 848: } 849: 850: /** 851: * Suspend the current Thread's execution for the specified amount of 852: * time. The Thread will not lose any locks it has during this time. There 853: * are no guarantees which thread will be next to run, but most VMs will 854: * choose the highest priority thread that has been waiting longest. 855: * 856: * @param ms the number of milliseconds to sleep, or 0 for forever 857: * @throws InterruptedException if the Thread is (or was) interrupted; 858: * it's <i>interrupted status</i> will be cleared 859: * @throws IllegalArgumentException if ms is negative 860: * @see #interrupt() 861: * @see #notify() 862: * @see #wait(long) 863: */ 864: public static void sleep(long ms) throws InterruptedException 865: { 866: sleep(ms, 0); 867: } 868: 869: /** 870: * Suspend the current Thread's execution for the specified amount of 871: * time. The Thread will not lose any locks it has during this time. There 872: * are no guarantees which thread will be next to run, but most VMs will 873: * choose the highest priority thread that has been waiting longest. 874: * <p> 875: * Note that 1,000,000 nanoseconds == 1 millisecond, but most VMs 876: * do not offer that fine a grain of timing resolution. When ms is 877: * zero and ns is non-zero the Thread will sleep for at least one 878: * milli second. There is no guarantee that this thread can start up 879: * immediately when time expires, because some other thread may be 880: * active. So don't expect real-time performance. 881: * 882: * @param ms the number of milliseconds to sleep, or 0 for forever 883: * @param ns the number of extra nanoseconds to sleep (0-999999) 884: * @throws InterruptedException if the Thread is (or was) interrupted; 885: * it's <i>interrupted status</i> will be cleared 886: * @throws IllegalArgumentException if ms or ns is negative 887: * or ns is larger than 999999. 888: * @see #interrupt() 889: * @see #notify() 890: * @see #wait(long, int) 891: */ 892: public static void sleep(long ms, int ns) throws InterruptedException 893: { 894: // Check parameters 895: if (ms < 0 ) 896: throw new IllegalArgumentException("Negative milliseconds: " + ms); 897: 898: if (ns < 0 || ns > 999999) 899: throw new IllegalArgumentException("Nanoseconds ouf of range: " + ns); 900: 901: // Really sleep 902: VMThread.sleep(ms, ns); 903: } 904: 905: /** 906: * Start this Thread, calling the run() method of the Runnable this Thread 907: * was created with, or else the run() method of the Thread itself. This 908: * is the only way to start a new thread; calling run by yourself will just 909: * stay in the same thread. The virtual machine will remove the thread from 910: * its thread group when the run() method completes. 911: * 912: * @throws IllegalThreadStateException if the thread has already started 913: * @see #run() 914: */ 915: public synchronized void start() 916: { 917: if (vmThread != null || group == null) 918: throw new IllegalThreadStateException(); 919: 920: VMThread.create(this, stacksize); 921: } 922: 923: /** 924: * Cause this Thread to stop abnormally because of the throw of a ThreadDeath 925: * error. If you stop a Thread that has not yet started, it will stop 926: * immediately when it is actually started. 927: * 928: * <p>This is inherently unsafe, as it can interrupt synchronized blocks and 929: * leave data in bad states. Hence, there is a security check: 930: * <code>checkAccess(this)</code>, plus another one if the current thread 931: * is not this: <code>RuntimePermission("stopThread")</code>. If you must 932: * catch a ThreadDeath, be sure to rethrow it after you have cleaned up. 933: * ThreadDeath is the only exception which does not print a stack trace when 934: * the thread dies. 935: * 936: * @throws SecurityException if you cannot stop the Thread 937: * @see #interrupt() 938: * @see #checkAccess() 939: * @see #start() 940: * @see ThreadDeath 941: * @see ThreadGroup#uncaughtException(Thread, Throwable) 942: * @see SecurityManager#checkAccess(Thread) 943: * @see SecurityManager#checkPermission(Permission) 944: * @deprecated unsafe operation, try not to use 945: */ 946: public final void stop() 947: { 948: stop(new ThreadDeath()); 949: } 950: 951: /** 952: * Cause this Thread to stop abnormally and throw the specified exception. 953: * If you stop a Thread that has not yet started, the stop is ignored 954: * (contrary to what the JDK documentation says). 955: * <b>WARNING</b>This bypasses Java security, and can throw a checked 956: * exception which the call stack is unprepared to handle. Do not abuse 957: * this power. 958: * 959: * <p>This is inherently unsafe, as it can interrupt synchronized blocks and 960: * leave data in bad states. Hence, there is a security check: 961: * <code>checkAccess(this)</code>, plus another one if the current thread 962: * is not this: <code>RuntimePermission("stopThread")</code>. If you must 963: * catch a ThreadDeath, be sure to rethrow it after you have cleaned up. 964: * ThreadDeath is the only exception which does not print a stack trace when 965: * the thread dies. 966: * 967: * @param t the Throwable to throw when the Thread dies 968: * @throws SecurityException if you cannot stop the Thread 969: * @throws NullPointerException in the calling thread, if t is null 970: * @see #interrupt() 971: * @see #checkAccess() 972: * @see #start() 973: * @see ThreadDeath 974: * @see ThreadGroup#uncaughtException(Thread, Throwable) 975: * @see SecurityManager#checkAccess(Thread) 976: * @see SecurityManager#checkPermission(Permission) 977: * @deprecated unsafe operation, try not to use 978: */ 979: public final synchronized void stop(Throwable t) 980: { 981: if (t == null) 982: throw new NullPointerException(); 983: // Bypass System.getSecurityManager, for bootstrap efficiency. 984: SecurityManager sm = SecurityManager.current; 985: if (sm != null) 986: { 987: sm.checkAccess(this); 988: if (this != currentThread() || !(t instanceof ThreadDeath)) 989: sm.checkPermission(new RuntimePermission("stopThread")); 990: } 991: VMThread vt = vmThread; 992: if (vt != null) 993: vt.stop(t); 994: else 995: stillborn = t; 996: } 997: 998: /** 999: * Suspend this Thread. It will not come back, ever, unless it is resumed. 1000: * 1001: * <p>This is inherently unsafe, as the suspended thread still holds locks, 1002: * and can potentially deadlock your program. Hence, there is a security 1003: * check: <code>checkAccess</code>. 1004: * 1005: * @throws SecurityException if you cannot suspend the Thread 1006: * @see #checkAccess() 1007: * @see #resume() 1008: * @deprecated unsafe operation, try not to use 1009: */ 1010: public final synchronized void suspend() 1011: { 1012: checkAccess(); 1013: VMThread t = vmThread; 1014: if (t != null) 1015: t.suspend(); 1016: } 1017: 1018: /** 1019: * Set this Thread's priority. There may be a security check, 1020: * <code>checkAccess</code>, then the priority is set to the smaller of 1021: * priority and the ThreadGroup maximum priority. 1022: * 1023: * @param priority the new priority for this Thread 1024: * @throws IllegalArgumentException if priority exceeds MIN_PRIORITY or 1025: * MAX_PRIORITY 1026: * @throws SecurityException if you cannot modify this Thread 1027: * @see #getPriority() 1028: * @see #checkAccess() 1029: * @see ThreadGroup#getMaxPriority() 1030: * @see #MIN_PRIORITY 1031: * @see #MAX_PRIORITY 1032: */ 1033: public final synchronized void setPriority(int priority) 1034: { 1035: checkAccess(); 1036: if (priority < MIN_PRIORITY || priority > MAX_PRIORITY) 1037: throw new IllegalArgumentException("Invalid thread priority value " 1038: + priority + "."); 1039: priority = Math.min(priority, group.getMaxPriority()); 1040: VMThread t = vmThread; 1041: if (t != null) 1042: t.setPriority(priority); 1043: else 1044: this.priority = priority; 1045: } 1046: 1047: /** 1048: * Returns a string representation of this thread, including the 1049: * thread's name, priority, and thread group. 1050: * 1051: * @return a human-readable String representing this Thread 1052: */ 1053: public String toString() 1054: { 1055: return ("Thread[" + name + "," + priority + "," 1056: + (group == null ? "" : group.getName()) + "]"); 1057: } 1058: 1059: /** 1060: * Clean up code, called by VMThread when thread dies. 1061: */ 1062: synchronized void die() 1063: { 1064: group.removeThread(this); 1065: vmThread = null; 1066: locals = null; 1067: } 1068: 1069: /** 1070: * Returns the map used by ThreadLocal to store the thread local values. 1071: */ 1072: static Map getThreadLocals() 1073: { 1074: Thread thread = currentThread(); 1075: Map locals = thread.locals; 1076: if (locals == null) 1077: { 1078: locals = thread.locals = new WeakIdentityHashMap(); 1079: } 1080: return locals; 1081: } 1082: 1083: /** 1084: * Assigns the given <code>UncaughtExceptionHandler</code> to this 1085: * thread. This will then be called if the thread terminates due 1086: * to an uncaught exception, pre-empting that of the 1087: * <code>ThreadGroup</code>. 1088: * 1089: * @param h the handler to use for this thread. 1090: * @throws SecurityException if the current thread can't modify this thread. 1091: * @since 1.5 1092: */ 1093: public void setUncaughtExceptionHandler(UncaughtExceptionHandler h) 1094: { 1095: SecurityManager sm = SecurityManager.current; // Be thread-safe. 1096: if (sm != null) 1097: sm.checkAccess(this); 1098: exceptionHandler = h; 1099: } 1100: 1101: /** 1102: * <p> 1103: * Returns the handler used when this thread terminates due to an 1104: * uncaught exception. The handler used is determined by the following: 1105: * </p> 1106: * <ul> 1107: * <li>If this thread has its own handler, this is returned.</li> 1108: * <li>If not, then the handler of the thread's <code>ThreadGroup</code> 1109: * object is returned.</li> 1110: * <li>If both are unavailable, then <code>null</code> is returned 1111: * (which can only happen when the thread was terminated since 1112: * then it won't have an associated thread group anymore).</li> 1113: * </ul> 1114: * 1115: * @return the appropriate <code>UncaughtExceptionHandler</code> or 1116: * <code>null</code> if one can't be obtained. 1117: * @since 1.5 1118: */ 1119: public UncaughtExceptionHandler getUncaughtExceptionHandler() 1120: { 1121: return exceptionHandler != null ? exceptionHandler : group; 1122: } 1123: 1124: /** 1125: * <p> 1126: * Sets the default uncaught exception handler used when one isn't 1127: * provided by the thread or its associated <code>ThreadGroup</code>. 1128: * This exception handler is used when the thread itself does not 1129: * have an exception handler, and the thread's <code>ThreadGroup</code> 1130: * does not override this default mechanism with its own. As the group 1131: * calls this handler by default, this exception handler should not defer 1132: * to that of the group, as it may lead to infinite recursion. 1133: * </p> 1134: * <p> 1135: * Uncaught exception handlers are used when a thread terminates due to 1136: * an uncaught exception. Replacing this handler allows default code to 1137: * be put in place for all threads in order to handle this eventuality. 1138: * </p> 1139: * 1140: * @param h the new default uncaught exception handler to use. 1141: * @throws SecurityException if a security manager is present and 1142: * disallows the runtime permission 1143: * "setDefaultUncaughtExceptionHandler". 1144: * @since 1.5 1145: */ 1146: public static void 1147: setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler h) 1148: { 1149: SecurityManager sm = SecurityManager.current; // Be thread-safe. 1150: if (sm != null) 1151: sm.checkPermission(new RuntimePermission("setDefaultUncaughtExceptionHandler")); 1152: defaultHandler = h; 1153: } 1154: 1155: /** 1156: * Returns the handler used by default when a thread terminates 1157: * unexpectedly due to an exception, or <code>null</code> if one doesn't 1158: * exist. 1159: * 1160: * @return the default uncaught exception handler. 1161: * @since 1.5 1162: */ 1163: public static UncaughtExceptionHandler getDefaultUncaughtExceptionHandler() 1164: { 1165: return defaultHandler; 1166: } 1167: 1168: /** 1169: * Returns the unique identifier for this thread. This ID is generated 1170: * on thread creation, and may be re-used on its death. 1171: * 1172: * @return a positive long number representing the thread's ID. 1173: * @since 1.5 1174: */ 1175: public long getId() 1176: { 1177: return threadId; 1178: } 1179: 1180: /** 1181: * <p> 1182: * This interface is used to handle uncaught exceptions 1183: * which cause a <code>Thread</code> to terminate. When 1184: * a thread, t, is about to terminate due to an uncaught 1185: * exception, the virtual machine looks for a class which 1186: * implements this interface, in order to supply it with 1187: * the dying thread and its uncaught exception. 1188: * </p> 1189: * <p> 1190: * The virtual machine makes two attempts to find an 1191: * appropriate handler for the uncaught exception, in 1192: * the following order: 1193: * </p> 1194: * <ol> 1195: * <li> 1196: * <code>t.getUncaughtExceptionHandler()</code> -- 1197: * the dying thread is queried first for a handler 1198: * specific to that thread. 1199: * </li> 1200: * <li> 1201: * <code>t.getThreadGroup()</code> -- 1202: * the thread group of the dying thread is used to 1203: * handle the exception. If the thread group has 1204: * no special requirements for handling the exception, 1205: * it may simply forward it on to 1206: * <code>Thread.getDefaultUncaughtExceptionHandler()</code>, 1207: * the default handler, which is used as a last resort. 1208: * </li> 1209: * </ol> 1210: * <p> 1211: * The first handler found is the one used to handle 1212: * the uncaught exception. 1213: * </p> 1214: * 1215: * @author Tom Tromey <tromey@redhat.com> 1216: * @author Andrew John Hughes <gnu_andrew@member.fsf.org> 1217: * @since 1.5 1218: * @see Thread#getUncaughtExceptionHandler() 1219: * @see Thread#setUncaughtExceptionHandler(UncaughtExceptionHandler) 1220: * @see Thread#getDefaultUncaughtExceptionHandler() 1221: * @see 1222: * Thread#setDefaultUncaughtExceptionHandler(java.lang.Thread.UncaughtExceptionHandler) 1223: */ 1224: public interface UncaughtExceptionHandler 1225: { 1226: /** 1227: * Invoked by the virtual machine with the dying thread 1228: * and the uncaught exception. Any exceptions thrown 1229: * by this method are simply ignored by the virtual 1230: * machine. 1231: * 1232: * @param thr the dying thread. 1233: * @param exc the uncaught exception. 1234: */ 1235: void uncaughtException(Thread thr, Throwable exc); 1236: } 1237: 1238: /** 1239: * <p> 1240: * Represents the current state of a thread, according to the VM rather 1241: * than the operating system. It can be one of the following: 1242: * </p> 1243: * <ul> 1244: * <li>NEW -- The thread has just been created but is not yet running.</li> 1245: * <li>RUNNABLE -- The thread is currently running or can be scheduled 1246: * to run.</li> 1247: * <li>BLOCKED -- The thread is blocked waiting on an I/O operation 1248: * or to obtain a lock.</li> 1249: * <li>WAITING -- The thread is waiting indefinitely for another thread 1250: * to do something.</li> 1251: * <li>TIMED_WAITING -- The thread is waiting for a specific amount of time 1252: * for another thread to do something.</li> 1253: * <li>TERMINATED -- The thread has exited.</li> 1254: * </ul> 1255: * 1256: * @since 1.5 1257: */ 1258: public enum State 1259: { 1260: BLOCKED, NEW, RUNNABLE, TERMINATED, TIMED_WAITING, WAITING; 1261: 1262: /** 1263: * For compatability with Sun's JDK 1264: */ 1265: private static final long serialVersionUID = 605505746047245783L; 1266: } 1267: 1268: 1269: /** 1270: * Returns the current state of the thread. This 1271: * is designed for monitoring thread behaviour, rather 1272: * than for synchronization control. 1273: * 1274: * @return the current thread state. 1275: */ 1276: public State getState() 1277: { 1278: VMThread t = vmThread; 1279: if (t != null) 1280: return State.valueOf(t.getState()); 1281: if (group == null) 1282: return State.TERMINATED; 1283: return State.NEW; 1284: } 1285: 1286: /** 1287: * <p> 1288: * Returns a map of threads to stack traces for each 1289: * live thread. The keys of the map are {@link Thread} 1290: * objects, which map to arrays of {@link StackTraceElement}s. 1291: * The results obtained from Calling this method are 1292: * equivalent to calling {@link getStackTrace()} on each 1293: * thread in succession. Threads may be executing while 1294: * this takes place, and the results represent a snapshot 1295: * of the thread at the time its {@link getStackTrace()} 1296: * method is called. 1297: * </p> 1298: * <p> 1299: * The stack trace information contains the methods called 1300: * by the thread, with the most recent method forming the 1301: * first element in the array. The array will be empty 1302: * if the virtual machine can not obtain information on the 1303: * thread. 1304: * </p> 1305: * <p> 1306: * To execute this method, the current security manager 1307: * (if one exists) must allow both the 1308: * <code>"getStackTrace"</code> and 1309: * <code>"modifyThreadGroup"</code> {@link RuntimePermission}s. 1310: * </p> 1311: * 1312: * @return a map of threads to arrays of {@link StackTraceElement}s. 1313: * @throws SecurityException if a security manager exists, and 1314: * prevents either or both the runtime 1315: * permissions specified above. 1316: * @since 1.5 1317: * @see #getStackTrace() 1318: */ 1319: public static Map<Thread, StackTraceElement[]> getAllStackTraces() 1320: { 1321: ThreadGroup group = currentThread().group; 1322: while (group.getParent() != null) 1323: group = group.getParent(); 1324: int arraySize = group.activeCount(); 1325: Thread[] threadList = new Thread[arraySize]; 1326: int filled = group.enumerate(threadList); 1327: while (filled == arraySize) 1328: { 1329: arraySize *= 2; 1330: threadList = new Thread[arraySize]; 1331: filled = group.enumerate(threadList); 1332: } 1333: Map traces = new HashMap(); 1334: for (int a = 0; a < filled; ++a) 1335: traces.put(threadList[a], 1336: threadList[a].getStackTrace()); 1337: return traces; 1338: } 1339: 1340: /** 1341: * <p> 1342: * Returns an array of {@link StackTraceElement}s 1343: * representing the current stack trace of this thread. 1344: * The first element of the array is the most recent 1345: * method called, and represents the top of the stack. 1346: * The elements continue in this order, with the last 1347: * element representing the bottom of the stack. 1348: * </p> 1349: * <p> 1350: * A zero element array is returned for threads which 1351: * have not yet started (and thus have not yet executed 1352: * any methods) or for those which have terminated. 1353: * Where the virtual machine can not obtain a trace for 1354: * the thread, an empty array is also returned. The 1355: * virtual machine may also omit some methods from the 1356: * trace in non-zero arrays. 1357: * </p> 1358: * <p> 1359: * To execute this method, the current security manager 1360: * (if one exists) must allow both the 1361: * <code>"getStackTrace"</code> and 1362: * <code>"modifyThreadGroup"</code> {@link RuntimePermission}s. 1363: * </p> 1364: * 1365: * @return a stack trace for this thread. 1366: * @throws SecurityException if a security manager exists, and 1367: * prevents the use of the 1368: * <code>"getStackTrace"</code> 1369: * permission. 1370: * @since 1.5 1371: * @see #getAllStackTraces() 1372: */ 1373: public StackTraceElement[] getStackTrace() 1374: { 1375: SecurityManager sm = SecurityManager.current; // Be thread-safe. 1376: if (sm != null) 1377: sm.checkPermission(new RuntimePermission("getStackTrace")); 1378: ThreadMXBean bean = ManagementFactory.getThreadMXBean(); 1379: ThreadInfo info = bean.getThreadInfo(threadId, Integer.MAX_VALUE); 1380: return info.getStackTrace(); 1381: } 1382: 1383: }
| GNU Classpath (0.95) |