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/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*/
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;
import junit.framework.TestSuite;
public class DoubleAccumulatorTest extends JSR166TestCase {
public static void main(String[] args) {
main(suite(), args);
}
public static Test suite() {
return new TestSuite(DoubleAccumulatorTest.class);
}
/**
* new instance initialized to supplied identity
*/
public void testConstructor() {
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 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 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 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 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 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 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 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 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 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();
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());
}
}
}
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