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6993789: LinkedBlockingDeque iterator/descendingIterator loops and owns lock forever

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Reviewed-by: dl, dholmes
This commit is contained in:
Chris Hegarty 2010-11-15 15:11:04 +00:00
parent 4dfa884fe5
commit cdcbbea8cb
2 changed files with 98 additions and 50 deletions
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94
jdk/src/share/classes/java/util/concurrent/LinkedBlockingDeque.java
View File

@ -126,10 +126,8 @@ public class LinkedBlockingDeque<E>
*/
Node<E> next;
Node(E x, Node<E> p, Node<E> n) {
Node(E x) {
item = x;
prev = p;
next = n;
}
}
@ -199,7 +197,7 @@ public class LinkedBlockingDeque<E>
for (E e : c) {
if (e == null)
throw new NullPointerException();
if (!linkLast(e))
if (!linkLast(new Node<E>(e)))
throw new IllegalStateException("Deque full");
}
} finally {
@ -211,38 +209,38 @@ public class LinkedBlockingDeque<E>
// Basic linking and unlinking operations, called only while holding lock
/**
* Links e as first element, or returns false if full.
* Links node as first element, or returns false if full.
*/
private boolean linkFirst(E e) {
private boolean linkFirst(Node<E> node) {
// assert lock.isHeldByCurrentThread();
if (count >= capacity)
return false;
Node<E> f = first;
Node<E> x = new Node<E>(e, null, f);
first = x;
node.next = f;
first = node;
if (last == null)
last = x;
last = node;
else
f.prev = x;
f.prev = node;
++count;
notEmpty.signal();
return true;
}
/**
* Links e as last element, or returns false if full.
* Links node as last element, or returns false if full.
*/
private boolean linkLast(E e) {
private boolean linkLast(Node<E> node) {
// assert lock.isHeldByCurrentThread();
if (count >= capacity)
return false;
Node<E> l = last;
Node<E> x = new Node<E>(e, l, null);
last = x;
node.prev = l;
last = node;
if (first == null)
first = x;
first = node;
else
l.next = x;
l.next = node;
++count;
notEmpty.signal();
return true;
@ -339,10 +337,11 @@ public class LinkedBlockingDeque<E>
*/
public boolean offerFirst(E e) {
if (e == null) throw new NullPointerException();
Node<E> node = new Node<E>(e);
final ReentrantLock lock = this.lock;
lock.lock();
try {
return linkFirst(e);
return linkFirst(node);
} finally {
lock.unlock();
}
@ -353,10 +352,11 @@ public class LinkedBlockingDeque<E>
*/
public boolean offerLast(E e) {
if (e == null) throw new NullPointerException();
Node<E> node = new Node<E>(e);
final ReentrantLock lock = this.lock;
lock.lock();
try {
return linkLast(e);
return linkLast(node);
} finally {
lock.unlock();
}
@ -368,10 +368,11 @@ public class LinkedBlockingDeque<E>
*/
public void putFirst(E e) throws InterruptedException {
if (e == null) throw new NullPointerException();
Node<E> node = new Node<E>(e);
final ReentrantLock lock = this.lock;
lock.lock();
try {
while (!linkFirst(e))
while (!linkFirst(node))
notFull.await();
} finally {
lock.unlock();
@ -384,10 +385,11 @@ public class LinkedBlockingDeque<E>
*/
public void putLast(E e) throws InterruptedException {
if (e == null) throw new NullPointerException();
Node<E> node = new Node<E>(e);
final ReentrantLock lock = this.lock;
lock.lock();
try {
while (!linkLast(e))
while (!linkLast(node))
notFull.await();
} finally {
lock.unlock();
@ -401,11 +403,12 @@ public class LinkedBlockingDeque<E>
public boolean offerFirst(E e, long timeout, TimeUnit unit)
throws InterruptedException {
if (e == null) throw new NullPointerException();
Node<E> node = new Node<E>(e);
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
while (!linkFirst(e)) {
while (!linkFirst(node)) {
if (nanos <= 0)
return false;
nanos = notFull.awaitNanos(nanos);
@ -423,11 +426,12 @@ public class LinkedBlockingDeque<E>
public boolean offerLast(E e, long timeout, TimeUnit unit)
throws InterruptedException {
if (e == null) throw new NullPointerException();
Node<E> node = new Node<E>(e);
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
while (!linkLast(e)) {
while (!linkLast(node)) {
if (nanos <= 0)
return false;
nanos = notFull.awaitNanos(nanos);
@ -955,7 +959,20 @@ public class LinkedBlockingDeque<E>
final ReentrantLock lock = this.lock;
lock.lock();
try {
return super.toString();
Node<E> p = first;
if (p == null)
return "[]";
StringBuilder sb = new StringBuilder();
sb.append('[');
for (;;) {
E e = p.item;
sb.append(e == this ? "(this Collection)" : e);
p = p.next;
if (p == null)
return sb.append(']').toString();
sb.append(',').append(' ');
}
} finally {
lock.unlock();
}
@ -1053,6 +1070,26 @@ public class LinkedBlockingDeque<E>
}
}
/**
* Returns the successor node of the given non-null, but
* possibly previously deleted, node.
*/
private Node<E> succ(Node<E> n) {
// Chains of deleted nodes ending in null or self-links
// are possible if multiple interior nodes are removed.
for (;;) {
Node<E> s = nextNode(n);
if (s == null)
return null;
else if (s.item != null)
return s;
else if (s == n)
return firstNode();
else
n = s;
}
}
/**
* Advances next.
*/
@ -1061,16 +1098,7 @@ public class LinkedBlockingDeque<E>
lock.lock();
try {
// assert next != null;
Node<E> s = nextNode(next);
if (s == next) {
next = firstNode();
} else {
// Skip over removed nodes.
// May be necessary if multiple interior Nodes are removed.
while (s != null && s.item == null)
s = nextNode(s);
next = s;
}
next = succ(next);
nextItem = (next == null) ? null : next.item;
} finally {
lock.unlock();

54
jdk/test/java/util/concurrent/ConcurrentQueues/IteratorWeakConsistency.java
View File

@ -56,23 +56,44 @@ public class IteratorWeakConsistency {
// test(new ArrayBlockingQueue(20));
}
void test(Queue q) throws Throwable {
void test(Queue q) {
// TODO: make this more general
for (int i = 0; i < 10; i++)
q.add(i);
Iterator it = q.iterator();
q.poll();
q.poll();
q.poll();
q.remove(7);
List list = new ArrayList();
while (it.hasNext())
list.add(it.next());
equal(list, Arrays.asList(0, 3, 4, 5, 6, 8, 9));
check(! list.contains(null));
System.out.printf("%s: %s%n",
q.getClass().getSimpleName(),
list);
try {
for (int i = 0; i < 10; i++)
q.add(i);
Iterator it = q.iterator();
q.poll();
q.poll();
q.poll();
q.remove(7);
List list = new ArrayList();
while (it.hasNext())
list.add(it.next());
equal(list, Arrays.asList(0, 3, 4, 5, 6, 8, 9));
check(! list.contains(null));
System.out.printf("%s: %s%n",
q.getClass().getSimpleName(),
list);
} catch (Throwable t) { unexpected(t); }
try {
q.clear();
q.add(1);
q.add(2);
q.add(3);
q.add(4);
Iterator it = q.iterator();
it.next();
q.remove(2);
q.remove(1);
q.remove(3);
boolean found4 = false;
while (it.hasNext()) {
found4 |= it.next().equals(4);
}
check(found4);
} catch (Throwable t) { unexpected(t); }
}
//--------------------- Infrastructure ---------------------------
@ -85,7 +106,6 @@ public class IteratorWeakConsistency {
void equal(Object x, Object y) {
if (x == null ? y == null : x.equals(y)) pass();
else fail(x + " not equal to " + y);}
static Class<?> thisClass = new Object(){}.getClass().getEnclosingClass();
public static void main(String[] args) throws Throwable {
new IteratorWeakConsistency().instanceMain(args);}
public void instanceMain(String[] args) throws Throwable {