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/*
* 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/
*/
package jsr166;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.atomic.DoubleAdder;
import junit.framework.Test;
import junit.framework.TestSuite;
public class DoubleAdderTest extends JSR166TestCase {
// android-note: Removed because the CTS runner does a bad job of
// retrying tests that have suite() declarations.
//
// public static void main(String[] args) {
// main(suite(), args);
// }
// public static Test suite() {
// return new TestSuite(DoubleAdderTest.class);
// }
/**
* default constructed initializes to zero
*/
public void testConstructor() {
DoubleAdder ai = new DoubleAdder();
assertEquals(0.0, ai.sum());
}
/**
* add adds given value to current, and sum returns current value
*/
public void testAddAndSum() {
DoubleAdder ai = new DoubleAdder();
ai.add(2.0);
assertEquals(2.0, ai.sum());
ai.add(-4.0);
assertEquals(-2.0, ai.sum());
}
/**
* reset() causes subsequent sum() to return zero
*/
public void testReset() {
DoubleAdder ai = new DoubleAdder();
ai.add(2.0);
assertEquals(2.0, ai.sum());
ai.reset();
assertEquals(0.0, ai.sum());
}
/**
* sumThenReset() returns sum; subsequent sum() returns zero
*/
public void testSumThenReset() {
DoubleAdder ai = new DoubleAdder();
ai.add(2.0);
assertEquals(2.0, ai.sum());
assertEquals(2.0, ai.sumThenReset());
assertEquals(0.0, ai.sum());
}
/**
* a deserialized serialized adder holds same value
*/
public void testSerialization() throws Exception {
DoubleAdder x = new DoubleAdder();
DoubleAdder y = serialClone(x);
assertNotSame(x, y);
x.add(-22.0);
DoubleAdder z = serialClone(x);
assertEquals(-22.0, x.sum());
assertEquals(0.0, y.sum());
assertEquals(-22.0, z.sum());
}
/**
* toString returns current value.
*/
public void testToString() {
DoubleAdder ai = new DoubleAdder();
assertEquals(Double.toString(0.0), ai.toString());
ai.add(1.0);
assertEquals(Double.toString(1.0), ai.toString());
}
/**
* intValue returns current value.
*/
public void testIntValue() {
DoubleAdder ai = new DoubleAdder();
assertEquals(0, ai.intValue());
ai.add(1.0);
assertEquals(1, ai.intValue());
}
/**
* longValue returns current value.
*/
public void testLongValue() {
DoubleAdder ai = new DoubleAdder();
assertEquals(0, ai.longValue());
ai.add(1.0);
assertEquals(1, ai.longValue());
}
/**
* floatValue returns current value.
*/
public void testFloatValue() {
DoubleAdder ai = new DoubleAdder();
assertEquals(0.0f, ai.floatValue());
ai.add(1.0);
assertEquals(1.0f, ai.floatValue());
}
/**
* doubleValue returns current value.
*/
public void testDoubleValue() {
DoubleAdder ai = new DoubleAdder();
assertEquals(0.0, ai.doubleValue());
ai.add(1.0);
assertEquals(1.0, ai.doubleValue());
}
/**
* adds by multiple threads produce correct sum
*/
public void testAddAndSumMT() throws Throwable {
final int incs = 1000000;
final int nthreads = 4;
final ExecutorService pool = Executors.newCachedThreadPool();
DoubleAdder a = new DoubleAdder();
CyclicBarrier barrier = new CyclicBarrier(nthreads + 1);
for (int i = 0; i < nthreads; ++i)
pool.execute(new AdderTask(a, barrier, incs));
barrier.await();
barrier.await();
double total = (long)nthreads * incs;
double sum = a.sum();
assertEquals(sum, total);
pool.shutdown();
}
static final class AdderTask implements Runnable {
final DoubleAdder adder;
final CyclicBarrier barrier;
final int incs;
volatile double result;
AdderTask(DoubleAdder adder, CyclicBarrier barrier, int incs) {
this.adder = adder;
this.barrier = barrier;
this.incs = incs;
}
public void run() {
try {
barrier.await();
DoubleAdder a = adder;
for (int i = 0; i < incs; ++i)
a.add(1.0);
result = a.sum();
barrier.await();
} catch (Throwable t) { throw new Error(t); }
}
}
}
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