Sample usages: * *
A {@code Phaser} may be used instead of a {@code CountDownLatch} - * to control a one-shot action serving a variable number of - * parties. The typical idiom is for the method setting this up to - * first register, then start the actions, then deregister, as in: + * to control a one-shot action serving a variable number of parties. + * The typical idiom is for the method setting this up to first + * register, then start the actions, then deregister, as in: * *
{@code
* void runTasks(List tasks) {
@@ -184,7 +184,7 @@ import java.util.concurrent.locks.LockSu
* 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:
+ * it registers with upon construction:
*
*
{@code
* void build(Task[] actions, int lo, int hi, Phaser ph) {
@@ -207,8 +207,6 @@ import java.util.concurrent.locks.LockSu
* be appropriate for extremely small per-barrier task bodies (thus
* high rates), or up to hundreds for extremely large ones.
*
- *
- *
* Implementation notes: This implementation restricts the
* maximum number of parties to 65535. Attempts to register additional
* parties result in {@code IllegalStateException}. However, you can and
@@ -348,7 +346,7 @@ public class Phaser {
}
/**
- * Creates a new phaser with the given numbers of registered
+ * Creates a new phaser with the given number of registered
* unarrived parties, initial phase number 0, and no parent.
*
* @param parties the number of parties required to trip barrier
@@ -380,7 +378,7 @@ public class Phaser {
}
/**
- * Creates a new phaser with the given parent and numbers of
+ * Creates a new phaser with the given parent and number of
* 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.
@@ -418,10 +416,11 @@ 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 additional parties required to trip barrier
* @return the arrival phase number to which this registration applied
* @throws IllegalStateException if attempting to register more
* than the maximum supported number of parties
+ * @throws IllegalArgumentException if {@code parties < 0}
*/
public int bulkRegister(int parties) {
if (parties < 0)
@@ -563,10 +562,10 @@ public class Phaser {
* Arrives at the barrier and awaits others. Equivalent in effect
* to {@code awaitAdvance(arrive())}. If you need to await with
* interruption or timeout, you can arrange this with an analogous
- * construction using one of the other forms of the awaitAdvance
- * method. If instead you need to deregister upon arrival use
- * {@code arriveAndDeregister}. It is an unenforced usage error
- * for an unregistered party to invoke this method.
+ * construction using one of the other forms of the {@code
+ * awaitAdvance} method. If instead you need to deregister upon
+ * arrival, use {@link #arriveAndDeregister}. It is an unenforced
+ * usage error for an unregistered party to invoke this method.
*
* @return the arrival phase number, or a negative number if terminated
* @throws IllegalStateException if not terminated and the number
@@ -829,6 +828,7 @@ public class Phaser {
volatile boolean wasInterrupted = false;
volatile Thread thread; // nulled to cancel wait
QNode next;
+
QNode(Phaser phaser, int phase, boolean interruptible,
boolean timed, long startTime, long nanos) {
this.phaser = phaser;
@@ -839,12 +839,14 @@ public class Phaser {
this.nanos = nanos;
thread = Thread.currentThread();
}
+
public boolean isReleasable() {
return (thread == null ||
phaser.getPhase() != phase ||
(interruptible && wasInterrupted) ||
(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
}
+
public boolean block() {
if (Thread.interrupted()) {
wasInterrupted = true;
@@ -861,6 +863,7 @@ public class Phaser {
}
return isReleasable();
}
+
void signal() {
Thread t = thread;
if (t != null) {
@@ -868,16 +871,17 @@ public class Phaser {
LockSupport.unpark(t);
}
}
+
boolean doWait() {
if (thread != null) {
try {
ForkJoinPool.managedBlock(this);
} catch (InterruptedException ie) {
+ wasInterrupted = true; // can't currently happen
}
}
return wasInterrupted;
}
-
}
/**
@@ -919,8 +923,8 @@ public class Phaser {
node = new QNode(this, phase, false, false, 0, 0);
else if (!queued)
queued = tryEnqueue(node);
- else
- interrupted = node.doWait();
+ else if (node.doWait())
+ interrupted = true;
}
if (node != null)
node.thread = null;
@@ -946,8 +950,8 @@ public class Phaser {
node = new QNode(this, phase, true, false, 0, 0);
else if (!queued)
queued = tryEnqueue(node);
- else
- interrupted = node.doWait();
+ else if (node.doWait())
+ interrupted = true;
}
if (node != null)
node.thread = null;
@@ -978,8 +982,8 @@ public class Phaser {
node = new QNode(this, phase, true, true, startTime, nanos);
else if (!queued)
queued = tryEnqueue(node);
- else
- interrupted = node.doWait();
+ else if (node.doWait())
+ interrupted = true;
}
if (node != null)
node.thread = null;