--- jsr166/src/jsr166y/Phaser.java 2009/03/19 05:10:42 1.12 +++ jsr166/src/jsr166y/Phaser.java 2009/07/21 00:15:14 1.14 @@ -93,18 +93,18 @@ import java.lang.reflect.*; * idiom is for the method setting this up to first register, then * start the actions, then deregister, as in: * - *
- *  void runTasks(List<Runnable> list) {
- *    final Phaser phaser = new Phaser(1); // "1" to register self
- *    for (Runnable r : list) {
- *      phaser.register();
- *      new Thread() {
- *        public void run() {
- *          phaser.arriveAndAwaitAdvance(); // await all creation
- *          r.run();
- *          phaser.arriveAndDeregister();   // signal completion
- *        }
- *      }.start();
+ *  
 {@code
+ * void runTasks(List list) {
+ *   final Phaser phaser = new Phaser(1); // "1" to register self
+ *   for (Runnable r : list) {
+ *     phaser.register();
+ *     new Thread() {
+ *       public void run() {
+ *         phaser.arriveAndAwaitAdvance(); // await all creation
+ *         r.run();
+ *         phaser.arriveAndDeregister();   // signal completion
+ *       }
+ *     }.start();
  *   }
  *
  *   doSomethingOnBehalfOfWorkers();
@@ -113,59 +113,55 @@ import java.lang.reflect.*;
  *   p = phaser.awaitAdvance(p); // ... and await arrival
  *   otherActions(); // do other things while tasks execute
  *   phaser.awaitAdvance(p); // await final completion
- * }
- * 
+ * }}
* *

One way to cause a set of threads to repeatedly perform actions * for a given number of iterations is to override {@code onAdvance}: * - *

- *  void startTasks(List<Runnable> list, final int iterations) {
- *    final Phaser phaser = new Phaser() {
- *       public boolean onAdvance(int phase, int registeredParties) {
- *         return phase >= iterations || registeredParties == 0;
+ *  
 {@code
+ * void startTasks(List list, final int iterations) {
+ *   final Phaser phaser = new Phaser() {
+ *     public boolean onAdvance(int phase, int registeredParties) {
+ *       return phase >= iterations || registeredParties == 0;
+ *     }
+ *   };
+ *   phaser.register();
+ *   for (Runnable r : list) {
+ *     phaser.register();
+ *     new Thread() {
+ *       public void run() {
+ *         do {
+ *           r.run();
+ *           phaser.arriveAndAwaitAdvance();
+ *         } while(!phaser.isTerminated();
  *       }
- *    };
- *    phaser.register();
- *    for (Runnable r : list) {
- *      phaser.register();
- *      new Thread() {
- *        public void run() {
- *           do {
- *             r.run();
- *             phaser.arriveAndAwaitAdvance();
- *           } while(!phaser.isTerminated();
- *        }
- *      }.start();
+ *     }.start();
  *   }
  *   phaser.arriveAndDeregister(); // deregister self, don't wait
- * }
- * 
+ * }}
* *

To create a set of tasks using a tree of Phasers, * you could use code of the following form, assuming a * Task class with a constructor accepting a Phaser that * it registers for upon construction: - *

- *  void build(Task[] actions, int lo, int hi, Phaser b) {
- *    int step = (hi - lo) / TASKS_PER_PHASER;
- *    if (step > 1) {
- *       int i = lo;
- *       while (i < hi) {
- *         int r = Math.min(i + step, hi);
- *         build(actions, i, r, new Phaser(b));
- *         i = r;
- *       }
- *    }
- *    else {
- *      for (int i = lo; i < hi; ++i)
- *        actions[i] = new Task(b);
- *        // assumes new Task(b) performs b.register()
- *    }
- *  }
- *  // .. initially called, for n tasks via
- *  build(new Task[n], 0, n, new Phaser());
- * 
+ *
 {@code
+ * void build(Task[] actions, int lo, int hi, Phaser b) {
+ *   int step = (hi - lo) / TASKS_PER_PHASER;
+ *   if (step > 1) {
+ *     int i = lo;
+ *     while (i < hi) {
+ *       int r = Math.min(i + step, hi);
+ *       build(actions, i, r, new Phaser(b));
+ *       i = r;
+ *     }
+ *   } else {
+ *     for (int i = lo; i < hi; ++i)
+ *       actions[i] = new Task(b);
+ *       // assumes new Task(b) performs b.register()
+ *   }
+ * }
+ * // .. initially called, for n tasks via
+ * build(new Task[n], 0, n, new Phaser());}
* * The best value of {@code TASKS_PER_PHASER} depends mainly on * expected barrier synchronization rates. A value as low as four may @@ -238,7 +234,7 @@ public class Phaser { } /** - * Returns message string for bad bounds exceptions + * Returns message string for bad bounds exceptions. */ private static String badBounds(int parties, int unarrived) { return ("Attempt to set " + unarrived + @@ -313,9 +309,10 @@ public class Phaser { /** * Creates a new Phaser with the given numbers of registered * unarrived parties, initial phase number 0, and no parent. - * @param parties the number of parties required to trip barrier. + * + * @param parties the number of parties required to trip barrier * @throws IllegalArgumentException if parties less than zero - * or greater than the maximum number of parties supported. + * or greater than the maximum number of parties supported */ public Phaser(int parties) { this(null, parties); @@ -326,7 +323,8 @@ public class Phaser { * initially registered parties. If parent is non-null this phaser * is registered with the parent and its initial phase number is * the same as that of parent phaser. - * @param parent the parent phaser. + * + * @param parent the parent phaser */ public Phaser(Phaser parent) { int phase = 0; @@ -342,13 +340,14 @@ public class Phaser { /** * Creates a new Phaser with the given parent and numbers of - * registered unarrived parties. If parent is non-null this phaser + * registered unarrived parties. If parent is non-null, this phaser * is registered with the parent and its initial phase number is * the same as that of parent phaser. - * @param parent the parent phaser. - * @param parties the number of parties required to trip barrier. + * + * @param parent the parent phaser + * @param parties the number of parties required to trip barrier * @throws IllegalArgumentException if parties less than zero - * or greater than the maximum number of parties supported. + * or greater than the maximum number of parties supported */ public Phaser(Phaser parent, int parties) { if (parties < 0 || parties > ushortMask) @@ -366,9 +365,10 @@ public class Phaser { /** * Adds a new unarrived party to this phaser. + * * @return the current barrier phase number upon registration * @throws IllegalStateException if attempting to register more - * than the maximum supported number of parties. + * than the maximum supported number of parties */ public int register() { return doRegister(1); @@ -376,10 +376,11 @@ public class Phaser { /** * Adds the given number of new unarrived parties to this phaser. - * @param parties the number of parties required to trip barrier. + * + * @param parties the number of parties required to trip barrier * @return the current barrier phase number upon registration * @throws IllegalStateException if attempting to register more - * than the maximum supported number of parties. + * than the maximum supported number of parties */ public int bulkRegister(int parties) { if (parties < 0) @@ -415,9 +416,9 @@ public class Phaser { * in turn wait for others via {@link #awaitAdvance}). * * @return the barrier phase number upon entry to this method, or a - * negative value if terminated; + * negative value if terminated * @throws IllegalStateException if not terminated and the number - * of unarrived parties would become negative. + * of unarrived parties would become negative */ public int arrive() { int phase; @@ -467,9 +468,9 @@ public class Phaser { * zero parties, this phaser is also deregistered from its parent. * * @return the current barrier phase number upon entry to - * this method, or a negative value if terminated; + * this method, or a negative value if terminated * @throws IllegalStateException if not terminated and the number - * of registered or unarrived parties would become negative. + * of registered or unarrived parties would become negative */ public int arriveAndDeregister() { // similar code to arrive, but too different to merge @@ -520,9 +521,10 @@ public class Phaser { * to {@code awaitAdvance(arrive())}. If you instead need to * await with interruption of timeout, and/or deregister upon * arrival, you can arrange them using analogous constructions. + * * @return the phase on entry to this method * @throws IllegalStateException if not terminated and the number - * of unarrived parties would become negative. + * of unarrived parties would become negative */ public int arriveAndAwaitAdvance() { return awaitAdvance(arrive()); @@ -532,6 +534,7 @@ public class Phaser { * Awaits the phase of the barrier to advance from the given * value, or returns immediately if argument is negative or this * barrier is terminated. + * * @param phase the phase on entry to this method * @return the phase on exit from this method */ @@ -553,6 +556,7 @@ public class Phaser { * value, or returns immediately if argument is negative or this * barrier is terminated, or throws InterruptedException if * interrupted while waiting. + * * @param phase the phase on entry to this method * @return the phase on exit from this method * @throws InterruptedException if thread interrupted while waiting @@ -574,6 +578,7 @@ public class Phaser { * Awaits the phase of the barrier to advance from the given value * or the given timeout elapses, or returns immediately if * argument is negative or this barrier is terminated. + * * @param phase the phase on entry to this method * @return the phase on exit from this method * @throws InterruptedException if thread interrupted while waiting @@ -620,6 +625,7 @@ public class Phaser { * Returns the current phase number. The maximum phase number is * {@code Integer.MAX_VALUE}, after which it restarts at * zero. Upon termination, the phase number is negative. + * * @return the phase number, or a negative value if terminated */ public final int getPhase() { @@ -628,6 +634,7 @@ public class Phaser { /** * Returns {@code true} if the current phase number equals the given phase. + * * @param phase the phase * @return {@code true} if the current phase number equals the given phase */ @@ -637,6 +644,7 @@ public class Phaser { /** * Returns the number of parties registered at this barrier. + * * @return the number of parties */ public int getRegisteredParties() { @@ -646,6 +654,7 @@ public class Phaser { /** * Returns the number of parties that have arrived at the current * phase of this barrier. + * * @return the number of arrived parties */ public int getArrivedParties() { @@ -655,6 +664,7 @@ public class Phaser { /** * Returns the number of registered parties that have not yet * arrived at the current phase of this barrier. + * * @return the number of unarrived parties */ public int getUnarrivedParties() { @@ -663,6 +673,7 @@ public class Phaser { /** * Returns the parent of this phaser, or null if none. + * * @return the parent of this phaser, or null if none */ public Phaser getParent() { @@ -672,6 +683,7 @@ public class Phaser { /** * Returns the root ancestor of this phaser, which is the same as * this phaser if it has no parent. + * * @return the root ancestor of this phaser */ public Phaser getRoot() { @@ -680,6 +692,7 @@ public class Phaser { /** * Returns {@code true} if this barrier has been terminated. + * * @return {@code true} if this barrier has been terminated */ public boolean isTerminated() { @@ -803,7 +816,7 @@ public class Phaser { } /** - * Removes and signals waiting threads from wait queue + * Removes and signals waiting threads from wait queue. */ private void releaseWaiters(int phase) { AtomicReference head = queueFor(phase); @@ -815,7 +828,8 @@ public class Phaser { } /** - * Tries to enqueue given node in the appropriate wait queue + * Tries to enqueue given node in the appropriate wait queue. + * * @return true if successful */ private boolean tryEnqueue(QNode node) { @@ -825,6 +839,7 @@ public class Phaser { /** * Enqueues node and waits unless aborted or signalled. + * * @return current phase */ private int untimedWait(int phase) {