java.util.concurrent.atomic.AtomicReferenceFieldUpdater#newUpdater()源码实例Demo

@Test
@Tag("PASSING")
@Order(2)
public void compareAndSetUsingAtomicReferenceFieldUpdater() {

    final AtomicReferenceFieldUpdater<TestSolutionCompareAndSet, Integer> valueUpdater =
            AtomicReferenceFieldUpdater.newUpdater(TestSolutionCompareAndSet.class,
                    Integer.class,
                    "privateVolatile");

    boolean exchanged = valueUpdater.compareAndSet(this, currentValue, newValue);

    assertTrue(exchanged,
            "The value should have been changed to 7, " +
                    "hence exchanged should be true"
            );

    assertEquals(newValue,
            valueUpdater.get(this),
            "The value of the privateVolatile should now be 7");

    exchanged = valueUpdater.compareAndSet(this, 2, 33);

    assertFalse(exchanged,
            "The value should not have changed since the expected value " +
                    "did not match, hence exchanged should be false"
            );

    assertEquals(newValue,
            valueUpdater.get(this),
            "The value of the privateVolatile should still be 7");
}
 

@Test
@Tag("PASSING")
@Order(2)
public void compareAndSetUsingAtomicReferenceFieldUpdater() {

    final AtomicReferenceFieldUpdater<TestKataCompareAndSet, Integer> valueUpdater =
            AtomicReferenceFieldUpdater.newUpdater(TestKataCompareAndSet.class,
                    Integer.class,
                    "privateVolatile");

    boolean exchanged = valueUpdater.compareAndSet(this, currentValue, newValue);

    assertTrue(exchanged,
            "The value should have been changed to 7, " +
                    "hence exchanged should be true"
            );

    assertEquals(newValue,
            valueUpdater.get(this),
            "The value of the privateVolatile should now be 7");

    exchanged = valueUpdater.compareAndSet(this, 2, 33);

    assertFalse(exchanged,
            "The value should not have changed since the expected value " +
                    "did not match, hence exchanged should be false"
            );

    assertEquals(newValue,
            valueUpdater.get(this),
            "The value of the privateVolatile should still be 7");
}
 

public static void main(String[] args) {
    Person person = new Person("zhangsan", 11, 170);
    person.setHobby(new Hobby("打球", "足球，篮球"));
    AtomicIntegerFieldUpdater<Person> atomicIntegerFieldUpdater = AtomicIntegerFieldUpdater.newUpdater(Person.class, "age");
    atomicIntegerFieldUpdater.addAndGet(person, 12);

    AtomicLongFieldUpdater<Person> atomicLongFieldUpdater = AtomicLongFieldUpdater.newUpdater(Person.class, "height");
    atomicLongFieldUpdater.addAndGet(person, 180);

    AtomicReferenceFieldUpdater<Person, Hobby> atomicReferenceFieldUpdater = AtomicReferenceFieldUpdater.newUpdater(Person.class, Hobby.class, "hobby");
    atomicReferenceFieldUpdater.getAndSet(person, new Hobby("打球", "排球，羽毛球"));

}
 

/**
 * Basic tests of the API : Simple function calls to exercise all of the functions listed in the API
 * specification for the AtomicReferenceFieldUpdater class.
 */	
public void testAPI()
{
	// =================================================================================
	// Create instances of AtomicReferenceFieldUpdater to work with
	
	for(int i = 0; i < updaters.length; i++)
	{
		updaters[i] = AtomicReferenceFieldUpdater.newUpdater(AtomicTestObject.class, String.class, "volatileString");
	}
	
	// =================================================================================
	// Basic API tests 
	
	assertEquals("1 : get()", "the answer", getRandomUpdater().get(testObject1));
	assertEquals("2 : get()", getRandomUpdater().get(testObject1), getRandomUpdater().get(testObject2));
	assertEquals("3 : get()", getRandomUpdater().get(testObject1), getRandomUpdater().get(testObject1));
	assertEquals("4 : get()", getRandomUpdater().get(testObject2), getRandomUpdater().get(testObject2));
	
	assertEquals("5 : getAndSet()", "the answer", getRandomUpdater().getAndSet(testObject1, "the question"));
	assertEquals("6 : get()", "the question", getRandomUpdater().get(testObject1));
	assertEquals("7 : getAndSet()", "the question", getRandomUpdater().getAndSet(testObject1, "the answer"));
	
	assertEquals("8 : compareAndSet()", true, getRandomUpdater().compareAndSet(testObject1, "the answer", "the question"));
	assertEquals("9 : compareAndSet()", true, getRandomUpdater().compareAndSet(testObject2, "the answer", "the question"));
	assertEquals("10: get()", getRandomUpdater().get(testObject1), getRandomUpdater().get(testObject2));
	assertEquals("11: compareAndSet()", false, getRandomUpdater().compareAndSet(testObject1, "the answer", "the question"));
	assertEquals("12: compareAndSet()", true, getRandomUpdater().compareAndSet(testObject1, "the question", "the answer"));		
}
 

public void checkPrivateAccess() {
    try {
        AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest,Integer> a =
            AtomicReferenceFieldUpdater.newUpdater
            (AtomicReferenceFieldUpdaterTest.class, Integer.class, "privateField");
        shouldThrow();
    } catch (RuntimeException success) {
        assertNotNull(success.getCause());
    }
}
 

public void checkCompareAndSetProtectedSub() {
    AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest,Integer> a =
        AtomicReferenceFieldUpdater.newUpdater
        (AtomicReferenceFieldUpdaterTest.class, Integer.class, "protectedField");
    this.protectedField = one;
    assertTrue(a.compareAndSet(this, one, two));
    assertTrue(a.compareAndSet(this, two, m4));
    assertSame(m4, a.get(this));
    assertFalse(a.compareAndSet(this, m5, seven));
    assertFalse(seven == a.get(this));
    assertTrue(a.compareAndSet(this, m4, seven));
    assertSame(seven, a.get(this));
}
 

public void checkPackageAccess(AtomicReferenceFieldUpdaterTest obj) {
    obj.x = one;
    AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest,Integer> a =
        AtomicReferenceFieldUpdater.newUpdater
        (AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
    assertSame(one, a.get(obj));
    assertTrue(a.compareAndSet(obj, one, two));
    assertSame(two, a.get(obj));
}
 

public void checkPrivateAccess(AtomicReferenceFieldUpdaterTest obj) {
    try {
        AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest,Integer> a =
            AtomicReferenceFieldUpdater.newUpdater
            (AtomicReferenceFieldUpdaterTest.class, Integer.class, "privateField");
        throw new AssertionError("should throw");
    } catch (RuntimeException success) {
        assertNotNull(success.getCause());
    }
}
 

/** compare raw numbers for atomic ops using JDK vs unsafe wrapper classes */
public void SW_testCompareAtomicOps() {

  final AtomicIntegerFieldUpdater<ConcurrentMapOpsTest> intJDKCounter =
      AtomicIntegerFieldUpdater.newUpdater(ConcurrentMapOpsTest.class,
          "intJDKCounter");
  final AtomicLongFieldUpdater<ConcurrentMapOpsTest> longJDKCounter =
      AtomicLongFieldUpdater.newUpdater(ConcurrentMapOpsTest.class,
          "longJDKCounter");
  final AtomicReferenceFieldUpdater<ConcurrentMapOpsTest, LongRef>
      refJDKCounter = AtomicReferenceFieldUpdater.newUpdater(
          ConcurrentMapOpsTest.class, LongRef.class, "refJDKCounter");

  final AtomicIntegerFieldUpdater<ConcurrentMapOpsTest> intUnsafeCounter =
      AtomicUpdaterFactory.newIntegerFieldUpdater(ConcurrentMapOpsTest.class,
          "intUnsafeCounter");
  final AtomicLongFieldUpdater<ConcurrentMapOpsTest> longUnsafeCounter =
      AtomicUpdaterFactory.newLongFieldUpdater(ConcurrentMapOpsTest.class,
          "longUnsafeCounter");
  final AtomicReferenceFieldUpdater<ConcurrentMapOpsTest, LongRef>
      refUnsafeCounter = AtomicUpdaterFactory.newReferenceFieldUpdater(
          ConcurrentMapOpsTest.class, LongRef.class, "refUnsafeCounter");

  // some warmups
  runAtomicOps(1, 50000, intJDKCounter, longJDKCounter, refJDKCounter,
      intUnsafeCounter, longUnsafeCounter, refUnsafeCounter);

  // timed runs with single threads to see the raw overheads with no
  // concurrency (as we would expect in most usual cases)
  runAtomicOps(1, 50000000, intJDKCounter, longJDKCounter, refJDKCounter,
      intUnsafeCounter, longUnsafeCounter, refUnsafeCounter);

  // now with concurrency
  runAtomicOps(5, 2000000, intJDKCounter, longJDKCounter, refJDKCounter,
      intUnsafeCounter, longUnsafeCounter, refUnsafeCounter);
}
 

/**
 * Creates and returns an updater for objects with the given reference field.
 */
public static <T, V> AtomicReferenceFieldUpdater<T, V> newReferenceFieldUpdater(
    Class<T> tclass, Class<V> vclass, String fieldName) {
  if (UnsafeHolder.hasUnsafe()) {
    return new UnsafeAtomicReferenceUpdater<T, V>(tclass, vclass, fieldName);
  }
  else {
    return AtomicReferenceFieldUpdater.newUpdater(tclass, vclass, fieldName);
  }
}
 

static private void testAtomicReferenceFieldUpdater() {
	System.out.println("AtomicTest.testAtomicReferenceFieldUpdater:");
	AtomicTest obj = new AtomicTest();
	AtomicReferenceFieldUpdater<AtomicTest, Integer> updater = AtomicReferenceFieldUpdater.newUpdater(AtomicTest.class, Integer.class, "value");
	System.out.println(updater.get(obj));
	updater.set(obj, 5);
	System.out.println(updater.get(obj));
	updater.compareAndSet(obj, 4, -4);
	System.out.println(updater.get(obj));
	updater.compareAndSet(obj, 5, -5);
	System.out.println(updater.get(obj));
}
 

/**
 * Creates and returns an updater for objects with the given field.
 *
 * @param tClass    the class of the objects holding the field.
 * @param vClass    the class of the field
 * @param fieldName the name of the field to be updated.
 */
public static <U, W> AtomicReferenceFieldUpdater<U, W> newAtomicReferenceFieldUpdater(
        Class<U> tClass, Class<W> vClass, String fieldName) {
    try {
        if (UnsafeUtil.hasUnsafe()) {
            return new UnsafeAtomicReferenceFieldUpdater<>(UnsafeUtil.getUnsafeAccessor().getUnsafe(), tClass, fieldName);
        } else {
            return AtomicReferenceFieldUpdater.newUpdater(tClass, vClass, fieldName);
        }
    } catch (Throwable t) {
        return AtomicReferenceFieldUpdater.newUpdater(tClass, vClass, fieldName);
    }
}
 

/** compare raw numbers for atomic ops using JDK vs unsafe wrapper classes */
public void SW_testCompareAtomicOps() {

  final AtomicIntegerFieldUpdater<ConcurrentMapOpsTest> intJDKCounter =
      AtomicIntegerFieldUpdater.newUpdater(ConcurrentMapOpsTest.class,
          "intJDKCounter");
  final AtomicLongFieldUpdater<ConcurrentMapOpsTest> longJDKCounter =
      AtomicLongFieldUpdater.newUpdater(ConcurrentMapOpsTest.class,
          "longJDKCounter");
  final AtomicReferenceFieldUpdater<ConcurrentMapOpsTest, LongRef>
      refJDKCounter = AtomicReferenceFieldUpdater.newUpdater(
          ConcurrentMapOpsTest.class, LongRef.class, "refJDKCounter");

  final AtomicIntegerFieldUpdater<ConcurrentMapOpsTest> intUnsafeCounter =
      AtomicUpdaterFactory.newIntegerFieldUpdater(ConcurrentMapOpsTest.class,
          "intUnsafeCounter");
  final AtomicLongFieldUpdater<ConcurrentMapOpsTest> longUnsafeCounter =
      AtomicUpdaterFactory.newLongFieldUpdater(ConcurrentMapOpsTest.class,
          "longUnsafeCounter");
  final AtomicReferenceFieldUpdater<ConcurrentMapOpsTest, LongRef>
      refUnsafeCounter = AtomicUpdaterFactory.newReferenceFieldUpdater(
          ConcurrentMapOpsTest.class, LongRef.class, "refUnsafeCounter");

  // some warmups
  runAtomicOps(1, 50000, intJDKCounter, longJDKCounter, refJDKCounter,
      intUnsafeCounter, longUnsafeCounter, refUnsafeCounter);

  // timed runs with single threads to see the raw overheads with no
  // concurrency (as we would expect in most usual cases)
  runAtomicOps(1, 50000000, intJDKCounter, longJDKCounter, refJDKCounter,
      intUnsafeCounter, longUnsafeCounter, refUnsafeCounter);

  // now with concurrency
  runAtomicOps(5, 2000000, intJDKCounter, longJDKCounter, refJDKCounter,
      intUnsafeCounter, longUnsafeCounter, refUnsafeCounter);
}
 

static <T, V> AtomicReferenceFieldUpdater<T, V> newRefUpdater(Class<T> tclass, Class<V> vclass, String fieldName) {
    if (AVAILABLE) {
        return AtomicReferenceFieldUpdater.newUpdater(tclass, vclass, fieldName);
    } else {
        return null;
    }
}
 

private static AtomicReferenceFieldUpdater<SessionImpl, Object> createTokenUpdater() {
    return AtomicReferenceFieldUpdater.newUpdater(SessionImpl.class, Object.class, "evictionToken");
}
 

private static AtomicReferenceFieldUpdater<SessionImpl, Object> createTokenUpdater() {
    return AtomicReferenceFieldUpdater.newUpdater(SessionImpl.class, Object.class, "evictionToken");
}
 

AtomicReferenceFieldUpdater<Atomic8Test,Integer> anIntegerFieldUpdater() {
    return AtomicReferenceFieldUpdater.newUpdater
        (Atomic8Test.class, Integer.class, "anIntegerField");
}
 

static AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> updaterFor(String fieldName) {
    return AtomicReferenceFieldUpdater.newUpdater
        (AtomicReferenceFieldUpdaterTest.class, Integer.class, fieldName);
}
 

AtomicReferenceFieldUpdater<Atomic8Test,Integer> anIntegerFieldUpdater() {
    return AtomicReferenceFieldUpdater.newUpdater
        (Atomic8Test.class, Integer.class, "anIntegerField");
}
 

static AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> updaterFor(String fieldName) {
    return AtomicReferenceFieldUpdater.newUpdater
        (AtomicReferenceFieldUpdaterTest.class, Integer.class, fieldName);
}