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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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|
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import java.util.concurrent.CyclicBarrier; |
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import java.util.concurrent.Executors; |
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import java.util.concurrent.ExecutorService; |
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import java.util.concurrent.atomic.DoubleAdder; |
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|
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import junit.framework.Test; |
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import junit.framework.TestSuite; |
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|
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public class DoubleAdderTest extends JSR166TestCase { |
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public static void main(String[] args) { |
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main(suite(), args); |
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} |
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public static Test suite() { |
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return new TestSuite(DoubleAdderTest.class); |
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} |
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|
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/** |
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* default constructed initializes to zero |
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*/ |
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public void testConstructor() { |
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DoubleAdder ai = new DoubleAdder(); |
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assertEquals(0.0, ai.sum()); |
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} |
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|
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/** |
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* add adds given value to current, and sum returns current value |
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*/ |
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public void testAddAndSum() { |
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DoubleAdder ai = new DoubleAdder(); |
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ai.add(2.0); |
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assertEquals(2.0, ai.sum()); |
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ai.add(-4.0); |
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assertEquals(-2.0, ai.sum()); |
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} |
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|
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/** |
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* reset() causes subsequent sum() to return zero |
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*/ |
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public void testReset() { |
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DoubleAdder ai = new DoubleAdder(); |
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ai.add(2.0); |
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assertEquals(2.0, ai.sum()); |
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ai.reset(); |
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assertEquals(0.0, ai.sum()); |
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} |
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|
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/** |
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* sumThenReset() returns sum; subsequent sum() returns zero |
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*/ |
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public void testSumThenReset() { |
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DoubleAdder ai = new DoubleAdder(); |
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ai.add(2.0); |
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assertEquals(2.0, ai.sum()); |
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assertEquals(2.0, ai.sumThenReset()); |
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assertEquals(0.0, ai.sum()); |
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} |
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|
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/** |
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* a deserialized/reserialized adder holds same value |
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*/ |
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public void testSerialization() throws Exception { |
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DoubleAdder x = new DoubleAdder(); |
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DoubleAdder y = serialClone(x); |
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assertNotSame(x, y); |
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x.add(-22.0); |
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DoubleAdder z = serialClone(x); |
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assertEquals(-22.0, x.sum()); |
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assertEquals(0.0, y.sum()); |
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assertEquals(-22.0, z.sum()); |
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} |
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|
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/** |
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* toString returns current value. |
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*/ |
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public void testToString() { |
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DoubleAdder ai = new DoubleAdder(); |
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assertEquals(Double.toString(0.0), ai.toString()); |
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ai.add(1.0); |
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assertEquals(Double.toString(1.0), ai.toString()); |
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} |
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|
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/** |
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* intValue returns current value. |
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*/ |
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public void testIntValue() { |
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DoubleAdder ai = new DoubleAdder(); |
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assertEquals(0, ai.intValue()); |
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ai.add(1.0); |
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assertEquals(1, ai.intValue()); |
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} |
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|
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/** |
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* longValue returns current value. |
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*/ |
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public void testLongValue() { |
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DoubleAdder ai = new DoubleAdder(); |
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assertEquals(0, ai.longValue()); |
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ai.add(1.0); |
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assertEquals(1, ai.longValue()); |
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} |
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|
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/** |
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* floatValue returns current value. |
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*/ |
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public void testFloatValue() { |
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DoubleAdder ai = new DoubleAdder(); |
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assertEquals(0.0f, ai.floatValue()); |
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ai.add(1.0); |
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assertEquals(1.0f, ai.floatValue()); |
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} |
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|
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/** |
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* doubleValue returns current value. |
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*/ |
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public void testDoubleValue() { |
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DoubleAdder ai = new DoubleAdder(); |
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assertEquals(0.0, ai.doubleValue()); |
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ai.add(1.0); |
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assertEquals(1.0, ai.doubleValue()); |
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} |
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|
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/** |
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* adds by multiple threads produce correct sum |
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*/ |
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public void testAddAndSumMT() throws Throwable { |
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final int incs = 1000000; |
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final int nthreads = 4; |
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final ExecutorService pool = Executors.newCachedThreadPool(); |
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DoubleAdder a = new DoubleAdder(); |
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CyclicBarrier barrier = new CyclicBarrier(nthreads + 1); |
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for (int i = 0; i < nthreads; ++i) |
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pool.execute(new AdderTask(a, barrier, incs)); |
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barrier.await(); |
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barrier.await(); |
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double total = (long)nthreads * incs; |
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double sum = a.sum(); |
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assertEquals(sum, total); |
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pool.shutdown(); |
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} |
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|
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static final class AdderTask implements Runnable { |
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final DoubleAdder adder; |
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final CyclicBarrier barrier; |
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final int incs; |
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volatile double result; |
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AdderTask(DoubleAdder adder, CyclicBarrier barrier, int incs) { |
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this.adder = adder; |
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this.barrier = barrier; |
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this.incs = incs; |
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} |
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|
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public void run() { |
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try { |
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barrier.await(); |
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DoubleAdder a = adder; |
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for (int i = 0; i < incs; ++i) |
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a.add(1.0); |
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result = a.sum(); |
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barrier.await(); |
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} catch (Throwable t) { throw new Error(t); } |
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} |
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} |
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|
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} |
