jsr166-tests/src/test/java/jsr166/AtomicIntegerTest.java

/*
 * 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/
 * Other contributors include Andrew Wright, Jeffrey Hayes,
 * Pat Fisher, Mike Judd.
 */

package jsr166;

import junit.framework.*;
import java.util.concurrent.atomic.AtomicInteger;

public class AtomicIntegerTest extends JSR166TestCase {

    final int[] VALUES = {
        Integer.MIN_VALUE, -1, 0, 1, 42, Integer.MAX_VALUE,
    };

    /**
     * constructor initializes to given value
     */
    public void testConstructor() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(1, ai.get());
    }

    /**
     * default constructed initializes to zero
     */
    public void testConstructor2() {
        AtomicInteger ai = new AtomicInteger();
        assertEquals(0, ai.get());
    }

    /**
     * get returns the last value set
     */
    public void testGetSet() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(1, ai.get());
        ai.set(2);
        assertEquals(2, ai.get());
        ai.set(-3);
        assertEquals(-3, ai.get());
    }

    /**
     * get returns the last value lazySet in same thread
     */
    public void testGetLazySet() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(1, ai.get());
        ai.lazySet(2);
        assertEquals(2, ai.get());
        ai.lazySet(-3);
        assertEquals(-3, ai.get());
    }

    /**
     * compareAndSet succeeds in changing value if equal to expected else fails
     */
    public void testCompareAndSet() {
        AtomicInteger ai = new AtomicInteger(1);
        assertTrue(ai.compareAndSet(1, 2));
        assertTrue(ai.compareAndSet(2, -4));
        assertEquals(-4, ai.get());
        assertFalse(ai.compareAndSet(-5, 7));
        assertEquals(-4, ai.get());
        assertTrue(ai.compareAndSet(-4, 7));
        assertEquals(7, ai.get());
    }

    /**
     * compareAndSet in one thread enables another waiting for value
     * to succeed
     */
    public void testCompareAndSetInMultipleThreads() throws Exception {
        final AtomicInteger ai = new AtomicInteger(1);
        Thread t = new Thread(new CheckedRunnable() {
            public void realRun() {
                while (!ai.compareAndSet(2, 3))
                    Thread.yield();
            }});

        t.start();
        assertTrue(ai.compareAndSet(1, 2));
        t.join(LONG_DELAY_MS);
        assertFalse(t.isAlive());
        assertEquals(3, ai.get());
    }

    /**
     * repeated weakCompareAndSet succeeds in changing value when equal
     * to expected
     */
    public void testWeakCompareAndSet() {
        AtomicInteger ai = new AtomicInteger(1);
        while (!ai.weakCompareAndSet(1, 2));
        while (!ai.weakCompareAndSet(2, -4));
        assertEquals(-4, ai.get());
        while (!ai.weakCompareAndSet(-4, 7));
        assertEquals(7, ai.get());
    }

    /**
     * getAndSet returns previous value and sets to given value
     */
    public void testGetAndSet() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(1, ai.getAndSet(0));
        assertEquals(0, ai.getAndSet(-10));
        assertEquals(-10, ai.getAndSet(1));
    }

    /**
     * getAndAdd returns previous value and adds given value
     */
    public void testGetAndAdd() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(1, ai.getAndAdd(2));
        assertEquals(3, ai.get());
        assertEquals(3, ai.getAndAdd(-4));
        assertEquals(-1, ai.get());
    }

    /**
     * getAndDecrement returns previous value and decrements
     */
    public void testGetAndDecrement() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(1, ai.getAndDecrement());
        assertEquals(0, ai.getAndDecrement());
        assertEquals(-1, ai.getAndDecrement());
    }

    /**
     * getAndIncrement returns previous value and increments
     */
    public void testGetAndIncrement() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(1, ai.getAndIncrement());
        assertEquals(2, ai.get());
        ai.set(-2);
        assertEquals(-2, ai.getAndIncrement());
        assertEquals(-1, ai.getAndIncrement());
        assertEquals(0, ai.getAndIncrement());
        assertEquals(1, ai.get());
    }

    /**
     * addAndGet adds given value to current, and returns current value
     */
    public void testAddAndGet() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(3, ai.addAndGet(2));
        assertEquals(3, ai.get());
        assertEquals(-1, ai.addAndGet(-4));
        assertEquals(-1, ai.get());
    }

    /**
     * decrementAndGet decrements and returns current value
     */
    public void testDecrementAndGet() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(0, ai.decrementAndGet());
        assertEquals(-1, ai.decrementAndGet());
        assertEquals(-2, ai.decrementAndGet());
        assertEquals(-2, ai.get());
    }

    /**
     * incrementAndGet increments and returns current value
     */
    public void testIncrementAndGet() {
        AtomicInteger ai = new AtomicInteger(1);
        assertEquals(2, ai.incrementAndGet());
        assertEquals(2, ai.get());
        ai.set(-2);
        assertEquals(-1, ai.incrementAndGet());
        assertEquals(0, ai.incrementAndGet());
        assertEquals(1, ai.incrementAndGet());
        assertEquals(1, ai.get());
    }

    /**
     * a deserialized serialized atomic holds same value
     */
    public void testSerialization() throws Exception {
        AtomicInteger x = new AtomicInteger();
        AtomicInteger y = serialClone(x);
        assertNotSame(x, y);
        x.set(22);
        AtomicInteger z = serialClone(x);
        assertEquals(22, x.get());
        assertEquals(0, y.get());
        assertEquals(22, z.get());
    }

    /**
     * toString returns current value.
     */
    public void testToString() {
        AtomicInteger ai = new AtomicInteger();
        assertEquals("0", ai.toString());
        for (int x : VALUES) {
            ai.set(x);
            assertEquals(Integer.toString(x), ai.toString());
        }
    }

    /**
     * intValue returns current value.
     */
    public void testIntValue() {
        AtomicInteger ai = new AtomicInteger();
        assertEquals(0, ai.intValue());
        for (int x : VALUES) {
            ai.set(x);
            assertEquals(x, ai.intValue());
        }
    }

    /**
     * longValue returns current value.
     */
    public void testLongValue() {
        AtomicInteger ai = new AtomicInteger();
        assertEquals(0L, ai.longValue());
        for (int x : VALUES) {
            ai.set(x);
            assertEquals((long)x, ai.longValue());
        }
    }

    /**
     * floatValue returns current value.
     */
    public void testFloatValue() {
        AtomicInteger ai = new AtomicInteger();
        assertEquals(0.0f, ai.floatValue());
        for (int x : VALUES) {
            ai.set(x);
            assertEquals((float)x, ai.floatValue());
        }
    }

    /**
     * doubleValue returns current value.
     */
    public void testDoubleValue() {
        AtomicInteger ai = new AtomicInteger();
        assertEquals(0.0d, ai.doubleValue());
        for (int x : VALUES) {
            ai.set(x);
            assertEquals((double)x, ai.doubleValue());
        }
    }

}