/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Written by Martin Buchholz 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/
*/
import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.ArrayDeque;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Queue;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ThreadLocalRandom;
/*
* @test
* @bug 7014263
* @modules java.base/java.util.concurrent:open
* @summary White box testing of ArrayBlockingQueue iterators.
*/
/**
* Tightly coupled to the implementation of ArrayBlockingQueue.
* Uses reflection to inspect queue and iterator state.
*/
@SuppressWarnings({"unchecked", "rawtypes"})
public class IteratorConsistency {
final ThreadLocalRandom rnd = ThreadLocalRandom.current();
final int CAPACITY = 20;
Field itrsField;
Field itemsField;
Field takeIndexField;
Field headField;
Field nextField;
Field prevTakeIndexField;
void test(String[] args) throws Throwable {
itrsField = ArrayBlockingQueue.class.getDeclaredField("itrs");
itemsField = ArrayBlockingQueue.class.getDeclaredField("items");
takeIndexField = ArrayBlockingQueue.class.getDeclaredField("takeIndex");
headField = Class.forName("java.util.concurrent.ArrayBlockingQueue$Itrs").getDeclaredField("head");
nextField = Class.forName("java.util.concurrent.ArrayBlockingQueue$Itrs$Node").getDeclaredField("next");
prevTakeIndexField = Class.forName("java.util.concurrent.ArrayBlockingQueue$Itr").getDeclaredField("prevTakeIndex");
itrsField.setAccessible(true);
itemsField.setAccessible(true);
takeIndexField.setAccessible(true);
headField.setAccessible(true);
nextField.setAccessible(true);
prevTakeIndexField.setAccessible(true);
test(CAPACITY, true);
test(CAPACITY, false);
}
Object itrs(ArrayBlockingQueue q) {
try {
return itrsField.get(q);
} catch (Throwable t) { throw new Error(); }
}
int takeIndex(ArrayBlockingQueue q) {
try {
return takeIndexField.getInt(q);
} catch (Throwable t) { throw new Error(); }
}
List<Iterator> trackedIterators(Object itrs) {
try {
List<Iterator> its = new ArrayList<Iterator>();
if (itrs != null)
for (Object p = headField.get(itrs); p != null; p = nextField.get(p))
its.add(((WeakReference<Iterator>)(p)).get());
Collections.reverse(its);
return its;
} catch (Throwable t) { throw new Error(); }
}
List<Iterator> trackedIterators(ArrayBlockingQueue q) {
return trackedIterators(itrs(q));
}
List<Iterator> attachedIterators(Object itrs) {
try {
List<Iterator> its = new ArrayList<Iterator>();
if (itrs != null)
for (Object p = headField.get(itrs); p != null; p = nextField.get(p)) {
Iterator it = ((WeakReference<Iterator>)(p)).get();
if (it != null && !isDetached(it))
its.add(it);
}
Collections.reverse(its);
return its;
} catch (Throwable t) { unexpected(t); return null; }
}
List<Iterator> attachedIterators(ArrayBlockingQueue q) {
return attachedIterators(itrs(q));
}
Object[] internalArray(ArrayBlockingQueue q) {
try {
return (Object[]) itemsField.get(q);
} catch (Throwable t) { throw new Error(t); }
}
void printInternalArray(ArrayBlockingQueue q) {
System.err.println(Arrays.toString(internalArray(q)));
}
void checkExhausted(Iterator it) {
if (rnd.nextBoolean()) {
check(!it.hasNext());
check(isDetached(it));
}
if (rnd.nextBoolean()) {
it.forEachRemaining(e -> { throw new AssertionError(); });
checkDetached(it);
}
if (rnd.nextBoolean())
try { it.next(); fail("should throw"); }
catch (NoSuchElementException success) {}
}
boolean isDetached(Iterator it) {
try {
return prevTakeIndexField.getInt(it) < 0;
} catch (IllegalAccessException t) { unexpected(t); return false; }
}
void checkDetached(Iterator it) {
check(isDetached(it));
}
void removeUsingIterator(ArrayBlockingQueue q, Object element) {
Iterator it = q.iterator();
while (it.hasNext()) {
Object x = it.next();
if (element.equals(x))
it.remove();
checkRemoveThrowsISE(it);
}
}
void checkRemoveThrowsISE(Iterator it) {
if (rnd.nextBoolean())
return;
try { it.remove(); fail("should throw"); }
catch (IllegalStateException success) {}
}
void checkRemoveHasNoEffect(Iterator it, Collection c) {
if (rnd.nextBoolean())
return;
int size = c.size();
it.remove(); // no effect
equal(c.size(), size);
checkRemoveThrowsISE(it);
}
void checkIterationSanity(Queue q) {
if (rnd.nextBoolean())
return;
int size = q.size();
Object[] a = q.toArray();
Object[] b = new Object[size+2];
Arrays.fill(b, Boolean.TRUE);
Object[] c = q.toArray(b);
equal(a.length, size);
check(b == c);
check(b[size] == null);
check(b[size+1] == Boolean.TRUE);
equal(q.toString(), Arrays.toString(a));
Integer[] xx = null, yy = null;
if (size > 0) {
xx = new Integer[size - 1];
Arrays.fill(xx, 42);
yy = ((Queue<Integer>)q).toArray(xx);
for (Integer zz : xx)
equal(42, zz);
}
Iterator it = q.iterator();
for (int i = 0; i < size; i++) {
check(it.hasNext());
Object x = it.next();
check(x == a[i]);
check(x == b[i]);
if (xx != null) check(x == yy[i]);
}
check(!it.hasNext());
}
private static void waitForFinalizersToRun() {
for (int i = 0; i < 2; i++)
tryWaitForFinalizersToRun();
}
private static void tryWaitForFinalizersToRun() {
System.gc();
final CountDownLatch fin = new CountDownLatch(1);
new Object() { protected void finalize() { fin.countDown(); }};
System.gc();
try { fin.await(); }
catch (InterruptedException ie) { throw new Error(ie); }
}
void test(int capacity, boolean fair) {
//----------------------------------------------------------------
// q.clear will clear out itrs.
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
for (int i = 0; i < capacity; i++)
check(q.add(i));
check(itrs(q) == null);
for (int i = 0; i < capacity; i++) {
its.add(q.iterator());
equal(trackedIterators(q), its);
q.poll();
q.add(capacity+i);
}
q.clear();
check(itrs(q) == null);
int j = 0;
for (Iterator it : its) {
if (rnd.nextBoolean())
check(it.hasNext());
equal(it.next(), j++);
checkExhausted(it);
}
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// q emptying will clear out itrs.
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
for (int i = 0; i < capacity; i++)
q.add(i);
check(itrs(q) == null);
for (int i = 0; i < capacity; i++) {
its.add(q.iterator());
equal(trackedIterators(q), its);
q.poll();
q.add(capacity+i);
}
for (int i = 0; i < capacity; i++)
q.poll();
check(itrs(q) == null);
int j = 0;
for (Iterator it : its) {
if (rnd.nextBoolean())
check(it.hasNext());
equal(it.next(), j++);
checkExhausted(it);
}
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Advancing 2 cycles will remove iterators.
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
for (int i = 0; i < capacity; i++)
q.add(i);
check(itrs(q) == null);
for (int i = capacity; i < 3 * capacity; i++) {
its.add(q.iterator());
equal(trackedIterators(q), its);
q.poll();
q.add(i);
}
for (int i = 3 * capacity; i < 4 * capacity; i++) {
equal(trackedIterators(q), its.subList(capacity,2*capacity));
q.poll();
q.add(i);
}
check(itrs(q) == null);
int j = 0;
for (Iterator it : its) {
if (rnd.nextBoolean())
check(it.hasNext());
equal(it.next(), j++);
checkExhausted(it);
}
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Interior removal of elements used by an iterator will cause
// it to be untracked.
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
q.add(0);
for (int i = 1; i < 2 * capacity; i++) {
q.add(i);
Integer[] elts = { -1, -2, -3 };
for (Integer elt : elts) q.add(elt);
equal(q.remove(), i - 1);
Iterator it = q.iterator();
equal(it.next(), i);
equal(it.next(), elts[0]);
Collections.shuffle(Arrays.asList(elts));
check(q.remove(elts[0]));
check(q.remove(elts[1]));
equal(trackedIterators(q), Collections.singletonList(it));
check(q.remove(elts[2]));
check(itrs(q) == null);
equal(it.next(), -2);
if (rnd.nextBoolean()) checkExhausted(it);
if (rnd.nextBoolean()) checkDetached(it);
}
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check iterators on an empty q
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
for (int i = 0; i < 4; i++) {
Iterator it = q.iterator();
check(itrs(q) == null);
if (rnd.nextBoolean()) checkExhausted(it);
if (rnd.nextBoolean()) checkDetached(it);
checkRemoveThrowsISE(it);
}
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check "interior" removal of iterator's last element
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
for (int i = 0; i < capacity; i++)
q.add(i);
for (int i = 0; i < capacity; i++) {
Iterator it = q.iterator();
its.add(it);
for (int j = 0; j < i; j++)
equal(j, it.next());
equal(attachedIterators(q), its);
}
q.remove(capacity - 1);
equal(attachedIterators(q), its);
for (int i = 1; i < capacity - 1; i++) {
q.remove(capacity - i - 1);
Iterator it = its.get(capacity - i);
checkDetached(it);
equal(attachedIterators(q), its.subList(0, capacity - i));
if (rnd.nextBoolean()) check(it.hasNext());
equal(it.next(), capacity - i);
checkExhausted(it);
}
equal(attachedIterators(q), its.subList(0, 2));
q.remove(0);
check(q.isEmpty());
check(itrs(q) == null);
Iterator it = its.get(0);
equal(it.next(), 0);
checkRemoveHasNoEffect(it, q);
checkExhausted(it);
checkDetached(it);
checkRemoveHasNoEffect(its.get(1), q);
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check "interior" removal of alternating elements, straddling 2 cycles
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
// Move takeIndex to middle
for (int i = 0; i < capacity/2; i++) {
check(q.add(i));
equal(q.poll(), i);
}
check(takeIndex(q) == capacity/2);
for (int i = 0; i < capacity; i++)
q.add(i);
for (int i = 0; i < capacity; i++) {
Iterator it = q.iterator();
its.add(it);
for (int j = 0; j < i; j++)
equal(j, it.next());
equal(attachedIterators(q), its);
}
// Remove all even elements, in either direction using
// q.remove(), or iterator.remove()
switch (rnd.nextInt(3)) {
case 0:
for (int i = 0; i < capacity; i+=2) {
check(q.remove(i));
equal(attachedIterators(q), its);
}
break;
case 1:
for (int i = capacity - 2; i >= 0; i-=2) {
check(q.remove(i));
equal(attachedIterators(q), its);
}
break;
case 2:
Iterator it = q.iterator();
while (it.hasNext()) {
int i = (Integer) it.next();
if ((i & 1) == 0)
it.remove();
}
equal(attachedIterators(q), its);
break;
default: throw new Error();
}
for (int i = 0; i < capacity; i++) {
Iterator it = its.get(i);
boolean even = ((i & 1) == 0);
if (even) {
if (rnd.nextBoolean()) check(it.hasNext());
equal(i, it.next());
for (int j = i+1; j < capacity; j += 2)
equal(j, it.next());
check(!isDetached(it));
check(!it.hasNext());
check(isDetached(it));
} else { /* odd */
if (rnd.nextBoolean()) check(it.hasNext());
checkRemoveHasNoEffect(it, q);
equal(i, it.next());
for (int j = i+2; j < capacity; j += 2)
equal(j, it.next());
check(!isDetached(it));
check(!it.hasNext());
check(isDetached(it));
}
}
equal(trackedIterators(q), Collections.emptyList());
check(itrs(q) == null);
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check garbage collection of discarded iterators
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
for (int i = 0; i < capacity; i++)
q.add(i);
for (int i = 0; i < capacity; i++) {
its.add(q.iterator());
equal(attachedIterators(q), its);
}
its = null;
waitForFinalizersToRun();
List<Iterator> trackedIterators = trackedIterators(q);
equal(trackedIterators.size(), capacity);
for (Iterator x : trackedIterators)
check(x == null);
Iterator it = q.iterator();
equal(trackedIterators(q), Collections.singletonList(it));
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check garbage collection of discarded iterators,
// with a randomly retained subset.
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
List<Iterator> retained = new ArrayList<Iterator>();
final int size = 1 + rnd.nextInt(capacity);
for (int i = 0; i < size; i++)
q.add(i);
for (int i = 0; i < size; i++) {
Iterator it = q.iterator();
its.add(it);
equal(attachedIterators(q), its);
}
// Leave sufficient gaps in retained
for (int i = 0; i < size; i+= 2+rnd.nextInt(3))
retained.add(its.get(i));
its = null;
waitForFinalizersToRun();
List<Iterator> trackedIterators = trackedIterators(q);
equal(trackedIterators.size(), size);
for (Iterator it : trackedIterators)
check((it == null) ^ retained.contains(it));
Iterator it = q.iterator(); // trigger another sweep
retained.add(it);
equal(trackedIterators(q), retained);
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check incremental sweeping of discarded iterators.
// Excessively white box?!
//----------------------------------------------------------------
try {
final int SHORT_SWEEP_PROBES = 4;
final int LONG_SWEEP_PROBES = 16;
final int PROBE_HOP = LONG_SWEEP_PROBES + 6 * SHORT_SWEEP_PROBES;
final int PROBE_HOP_COUNT = 10;
// Expect around 8 sweeps per PROBE_HOP
final int SWEEPS_PER_PROBE_HOP = 8;
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
for (int i = 0; i < capacity; i++)
q.add(i);
for (int i = 0; i < PROBE_HOP_COUNT * PROBE_HOP; i++) {
its.add(q.iterator());
equal(attachedIterators(q), its);
}
// make some garbage, separated by PROBE_HOP
for (int i = 0; i < its.size(); i += PROBE_HOP)
its.set(i, null);
waitForFinalizersToRun();
int retries;
for (retries = 0;
trackedIterators(q).contains(null) && retries < 1000;
retries++)
// one round of sweeping
its.add(q.iterator());
check(retries >= PROBE_HOP_COUNT * (SWEEPS_PER_PROBE_HOP - 2));
check(retries <= PROBE_HOP_COUNT * (SWEEPS_PER_PROBE_HOP + 2));
Iterator itsit = its.iterator();
while (itsit.hasNext())
if (itsit.next() == null)
itsit.remove();
equal(trackedIterators(q), its);
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check safety of iterator.remove while in detached mode.
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
List<Iterator> its = new ArrayList<Iterator>();
for (int i = 0; i < capacity/2; i++) {
q.add(i);
q.remove();
}
check(takeIndex(q) == capacity/2);
for (int i = 0; i < capacity; i++)
q.add(i);
for (int i = 0; i < capacity; i++) {
Iterator it = q.iterator();
its.add(it);
for (int j = 0; j < i; j++)
equal(j, it.next());
equal(attachedIterators(q), its);
}
for (int i = capacity - 1; i >= 0; i--) {
Iterator it = its.get(i);
equal(i, it.next()); // last element
check(!isDetached(it));
check(!it.hasNext()); // first hasNext failure
check(isDetached(it));
int size = q.size();
check(q.contains(i));
switch (rnd.nextInt(3)) {
case 0:
it.remove();
check(!q.contains(i));
equal(q.size(), size - 1);
break;
case 1:
// replace i with impostor
if (q.remainingCapacity() == 0) {
check(q.remove(i));
check(q.add(-1));
} else {
check(q.add(-1));
check(q.remove(i));
}
it.remove(); // should have no effect
equal(size, q.size());
check(q.contains(-1));
check(q.remove(-1));
break;
case 2:
// replace i with true impostor
if (i != 0) {
check(q.remove(i));
check(q.add(i));
}
it.remove();
check(!q.contains(i));
equal(q.size(), size - 1);
break;
default: throw new Error();
}
checkRemoveThrowsISE(it);
check(isDetached(it));
check(!trackedIterators(q).contains(it));
}
check(q.isEmpty());
check(itrs(q) == null);
for (Iterator it : its)
checkExhausted(it);
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check dequeues bypassing iterators' current positions.
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
Queue<Iterator> its0
= new ArrayDeque<Iterator>();
Queue<Iterator> itsMid
= new ArrayDeque<Iterator>();
List<Iterator> its = new ArrayList<Iterator>();
for (int i = 0; i < capacity; i++)
q.add(i);
for (int i = 0; i < 2 * capacity + 1; i++) {
Iterator it = q.iterator();
its.add(it);
its0.add(it);
}
for (int i = 0; i < 2 * capacity + 1; i++) {
Iterator it = q.iterator();
for (int j = 0; j < capacity/2; j++)
equal(j, it.next());
its.add(it);
itsMid.add(it);
}
for (int i = capacity; i < 3 * capacity; i++) {
Iterator it;
it = its0.remove();
checkRemoveThrowsISE(it);
if (rnd.nextBoolean()) check(it.hasNext());
equal(0, it.next());
int victim = i - capacity;
for (int j = victim + (victim == 0 ? 1 : 0); j < i; j++) {
if (rnd.nextBoolean()) check(it.hasNext());
equal(j, it.next());
}
checkExhausted(it);
it = itsMid.remove();
if (victim >= capacity/2)
checkRemoveHasNoEffect(it, q);
equal(capacity/2, it.next());
if (victim > capacity/2)
checkRemoveHasNoEffect(it, q);
for (int j = Math.max(victim, capacity/2 + 1); j < i; j++) {
if (rnd.nextBoolean()) check(it.hasNext());
equal(j, it.next());
}
checkExhausted(it);
if (rnd.nextBoolean()) {
equal(victim, q.remove());
} else {
ArrayList list = new ArrayList(1);
q.drainTo(list, 1);
equal(list.size(), 1);
equal(victim, list.get(0));
}
check(q.add(i));
}
// takeIndex has wrapped twice.
Iterator it0 = its0.remove();
Iterator itMid = itsMid.remove();
check(isDetached(it0));
check(isDetached(itMid));
if (rnd.nextBoolean()) check(it0.hasNext());
if (rnd.nextBoolean()) check(itMid.hasNext());
checkRemoveThrowsISE(it0);
checkRemoveHasNoEffect(itMid, q);
if (rnd.nextBoolean()) equal(0, it0.next());
if (rnd.nextBoolean()) equal(capacity/2, itMid.next());
check(isDetached(it0));
check(isDetached(itMid));
equal(capacity, q.size());
equal(0, q.remainingCapacity());
} catch (Throwable t) { unexpected(t); }
//----------------------------------------------------------------
// Check collective sanity of iteration, toArray() and toString()
//----------------------------------------------------------------
try {
ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
for (int i = 0; i < capacity; i++) {
checkIterationSanity(q);
equal(capacity, q.size() + q.remainingCapacity());
q.add(i);
}
for (int i = 0; i < (capacity + (capacity >> 1)); i++) {
checkIterationSanity(q);
equal(capacity, q.size() + q.remainingCapacity());
equal(i, q.peek());
equal(i, q.poll());
checkIterationSanity(q);
equal(capacity, q.size() + q.remainingCapacity());
q.add(capacity + i);
}
for (int i = 0; i < capacity; i++) {
checkIterationSanity(q);
equal(capacity, q.size() + q.remainingCapacity());
int expected = i + capacity + (capacity >> 1);
equal(expected, q.peek());
equal(expected, q.poll());
}
checkIterationSanity(q);
} catch (Throwable t) { unexpected(t); }
}
//--------------------- Infrastructure ---------------------------
volatile int passed = 0, failed = 0;
void pass() {passed++;}
void fail() {failed++; Thread.dumpStack();}
void fail(String msg) {System.err.println(msg); fail();}
void unexpected(Throwable t) {failed++; t.printStackTrace();}
void check(boolean cond) {if (cond) pass(); else fail();}
void equal(Object x, Object y) {
if (x == null ? y == null : x.equals(y)) pass();
else fail(x + " not equal to " + y);}
public static void main(String[] args) throws Throwable {
new IteratorConsistency().instanceMain(args);}
public void instanceMain(String[] args) throws Throwable {
try {test(args);} catch (Throwable t) {unexpected(t);}
System.err.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
if (failed > 0) throw new AssertionError("Some tests failed");}
}