--- a/jdk/test/java/util/concurrent/tck/DoubleAccumulatorTest.java Sat Jul 22 09:13:53 2017 -0700
+++ b/jdk/test/java/util/concurrent/tck/DoubleAccumulatorTest.java Sat Jul 22 09:18:50 2017 -0700
@@ -34,6 +34,7 @@
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Phaser;
+import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.DoubleAccumulator;
import junit.framework.Test;
@@ -48,135 +49,130 @@
}
/**
- * default constructed initializes to zero
+ * new instance initialized to supplied identity
*/
public void testConstructor() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- assertEquals(0.0, ai.get());
+ for (double identity : new double[] {
+ Double.NEGATIVE_INFINITY,
+ Double.POSITIVE_INFINITY,
+ Double.MIN_VALUE,
+ Double.MAX_VALUE,
+ 0.0,
+ })
+ assertEquals(identity,
+ new DoubleAccumulator(Double::max, identity).get());
}
/**
* accumulate accumulates given value to current, and get returns current value
*/
public void testAccumulateAndGet() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- ai.accumulate(2.0);
- assertEquals(2.0, ai.get());
- ai.accumulate(-4.0);
- assertEquals(2.0, ai.get());
- ai.accumulate(4.0);
- assertEquals(4.0, ai.get());
+ DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
+ acc.accumulate(2.0);
+ assertEquals(2.0, acc.get());
+ acc.accumulate(-4.0);
+ assertEquals(2.0, acc.get());
+ acc.accumulate(4.0);
+ assertEquals(4.0, acc.get());
}
/**
* reset() causes subsequent get() to return zero
*/
public void testReset() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- ai.accumulate(2.0);
- assertEquals(2.0, ai.get());
- ai.reset();
- assertEquals(0.0, ai.get());
+ DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
+ acc.accumulate(2.0);
+ assertEquals(2.0, acc.get());
+ acc.reset();
+ assertEquals(0.0, acc.get());
}
/**
* getThenReset() returns current value; subsequent get() returns zero
*/
public void testGetThenReset() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- ai.accumulate(2.0);
- assertEquals(2.0, ai.get());
- assertEquals(2.0, ai.getThenReset());
- assertEquals(0.0, ai.get());
+ DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
+ acc.accumulate(2.0);
+ assertEquals(2.0, acc.get());
+ assertEquals(2.0, acc.getThenReset());
+ assertEquals(0.0, acc.get());
}
/**
* toString returns current value.
*/
public void testToString() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- assertEquals("0.0", ai.toString());
- ai.accumulate(1.0);
- assertEquals(Double.toString(1.0), ai.toString());
+ DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
+ assertEquals("0.0", acc.toString());
+ acc.accumulate(1.0);
+ assertEquals(Double.toString(1.0), acc.toString());
}
/**
* intValue returns current value.
*/
public void testIntValue() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- assertEquals(0, ai.intValue());
- ai.accumulate(1.0);
- assertEquals(1, ai.intValue());
+ DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
+ assertEquals(0, acc.intValue());
+ acc.accumulate(1.0);
+ assertEquals(1, acc.intValue());
}
/**
* longValue returns current value.
*/
public void testLongValue() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- assertEquals(0, ai.longValue());
- ai.accumulate(1.0);
- assertEquals(1, ai.longValue());
+ DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
+ assertEquals(0, acc.longValue());
+ acc.accumulate(1.0);
+ assertEquals(1, acc.longValue());
}
/**
* floatValue returns current value.
*/
public void testFloatValue() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- assertEquals(0.0f, ai.floatValue());
- ai.accumulate(1.0);
- assertEquals(1.0f, ai.floatValue());
+ DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
+ assertEquals(0.0f, acc.floatValue());
+ acc.accumulate(1.0);
+ assertEquals(1.0f, acc.floatValue());
}
/**
* doubleValue returns current value.
*/
public void testDoubleValue() {
- DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
- assertEquals(0.0, ai.doubleValue());
- ai.accumulate(1.0);
- assertEquals(1.0, ai.doubleValue());
+ DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
+ assertEquals(0.0, acc.doubleValue());
+ acc.accumulate(1.0);
+ assertEquals(1.0, acc.doubleValue());
}
/**
* accumulates by multiple threads produce correct result
*/
public void testAccumulateAndGetMT() {
- final int incs = 1000000;
- final int nthreads = 4;
- final ExecutorService pool = Executors.newCachedThreadPool();
- DoubleAccumulator a = new DoubleAccumulator(Double::max, 0.0);
- Phaser phaser = new Phaser(nthreads + 1);
- for (int i = 0; i < nthreads; ++i)
- pool.execute(new AccTask(a, phaser, incs));
- phaser.arriveAndAwaitAdvance();
- phaser.arriveAndAwaitAdvance();
- double expected = incs - 1;
- double result = a.get();
- assertEquals(expected, result);
- pool.shutdown();
- }
-
- static final class AccTask implements Runnable {
- final DoubleAccumulator acc;
- final Phaser phaser;
- final int incs;
- volatile double result;
- AccTask(DoubleAccumulator acc, Phaser phaser, int incs) {
- this.acc = acc;
- this.phaser = phaser;
- this.incs = incs;
- }
-
- public void run() {
+ final DoubleAccumulator acc
+ = new DoubleAccumulator((x, y) -> x + y, 0.0);
+ final int nThreads = ThreadLocalRandom.current().nextInt(1, 5);
+ final Phaser phaser = new Phaser(nThreads + 1);
+ final int incs = 1_000_000;
+ final double total = nThreads * incs/2.0 * (incs - 1); // Gauss
+ final Runnable task = () -> {
phaser.arriveAndAwaitAdvance();
- DoubleAccumulator a = acc;
- for (int i = 0; i < incs; ++i)
- a.accumulate(i);
- result = a.get();
+ for (int i = 0; i < incs; i++) {
+ acc.accumulate((double) i);
+ assertTrue(acc.get() <= total);
+ }
phaser.arrive();
+ };
+ final ExecutorService p = Executors.newCachedThreadPool();
+ try (PoolCleaner cleaner = cleaner(p)) {
+ for (int i = nThreads; i-->0; )
+ p.execute(task);
+ phaser.arriveAndAwaitAdvance();
+ phaser.arriveAndAwaitAdvance();
+ assertEquals(total, acc.get());
}
}