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/* |
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* Written by Martin Buchholz with assistance from members of JCP |
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* JSR-166 Expert Group and released to the public domain, as |
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* explained at http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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|
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/* |
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* @test |
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* @modules java.base/java.util:open |
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* @run testng WhiteBox |
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* @summary White box tests of implementation details |
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*/ |
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|
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import static org.testng.Assert.*; |
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import org.testng.annotations.Test; |
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|
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import java.io.ByteArrayInputStream; |
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import java.io.ByteArrayOutputStream; |
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import java.io.ObjectInputStream; |
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import java.io.ObjectOutputStream; |
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import java.lang.invoke.MethodHandles; |
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import java.lang.invoke.VarHandle; |
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import java.util.ArrayDeque; |
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import java.util.concurrent.ThreadLocalRandom; |
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|
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@Test |
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public class WhiteBox { |
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final ThreadLocalRandom rnd = ThreadLocalRandom.current(); |
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final VarHandle ELEMENTS, HEAD, TAIL; |
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|
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WhiteBox() throws ReflectiveOperationException { |
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Class<?> klazz = ArrayDeque.class; |
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MethodHandles.Lookup lookup |
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= MethodHandles.privateLookupIn(klazz, MethodHandles.lookup()); |
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ELEMENTS = lookup.findVarHandle(klazz, "elements", Object[].class); |
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HEAD = lookup.findVarHandle(klazz, "head", int.class); |
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TAIL = lookup.findVarHandle(klazz, "tail", int.class); |
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} |
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|
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Object[] elements(ArrayDeque d) { return (Object[]) ELEMENTS.get(d); } |
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int head(ArrayDeque d) { return (int) HEAD.get(d); } |
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int tail(ArrayDeque d) { return (int) TAIL.get(d); } |
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|
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void checkCapacity(ArrayDeque d, int capacity) { |
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assertTrue(d.isEmpty()); |
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assertEquals(0, head(d)); |
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assertEquals(0, tail(d)); |
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Object[] initialElements = elements(d); |
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|
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assertInvariants(d); |
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for (int i = capacity; i--> 0; ) { |
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d.add(rnd.nextInt(42)); |
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assertSame(elements(d), initialElements); |
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assertInvariants(d); |
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} |
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|
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d.add(rnd.nextInt(42)); |
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assertNotSame(elements(d), initialElements); |
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assertInvariants(d); |
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} |
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|
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@Test |
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public void defaultConstructor() { |
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checkCapacity(new ArrayDeque(), 16); |
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} |
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|
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@Test |
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public void shouldNotResizeWhenInitialCapacityProvided() { |
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int initialCapacity = rnd.nextInt(20); |
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checkCapacity(new ArrayDeque(initialCapacity), initialCapacity); |
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} |
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|
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byte[] serialBytes(Object o) { |
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try { |
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ByteArrayOutputStream bos = new ByteArrayOutputStream(); |
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ObjectOutputStream oos = new ObjectOutputStream(bos); |
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oos.writeObject(o); |
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oos.flush(); |
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oos.close(); |
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return bos.toByteArray(); |
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} catch (Exception fail) { |
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throw new AssertionError(fail); |
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} |
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} |
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|
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@SuppressWarnings("unchecked") |
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<T> T serialClone(T o) { |
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try { |
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ObjectInputStream ois = new ObjectInputStream |
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(new ByteArrayInputStream(serialBytes(o))); |
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T clone = (T) ois.readObject(); |
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assertNotSame(o, clone); |
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assertSame(o.getClass(), clone.getClass()); |
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return clone; |
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} catch (Exception fail) { |
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throw new AssertionError(fail); |
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} |
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} |
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|
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@Test |
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public void testSerialization() { |
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ArrayDeque[] ds = { new ArrayDeque(), new ArrayDeque(rnd.nextInt(20)) }; |
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for (ArrayDeque d : ds) { |
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if (rnd.nextBoolean()) d.add(99); |
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ArrayDeque clone = serialClone(d); |
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assertInvariants(clone); |
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assertNotSame(elements(d), elements(clone)); |
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assertEquals(d, clone); |
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} |
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} |
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|
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/** Checks conditions which should always be true. */ |
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void assertInvariants(ArrayDeque d) { |
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final Object[] elements = elements(d); |
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final int head = head(d); |
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final int tail = tail(d); |
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final int capacity = elements.length; |
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assertTrue(0 <= head && head < capacity); |
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assertTrue(0 <= tail && tail < capacity); |
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assertTrue(capacity > 0); |
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assertTrue(d.size() < capacity); |
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assertTrue((head == tail) ^ (elements[head] != null)); |
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assertNull(elements[tail]); |
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assertTrue((head == tail) ^ (elements[Math.floorMod(tail - 1, capacity)] != null)); |
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} |
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} |
