/**
* Retrieves and removes the head of this queue, waiting if necessary until an element with an
* expired delay is available on this queue.
*
* @return the head of this queue
* @throws InterruptedException {@inheritDoc}
*/
public E take() throws InterruptedException {
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
for (; ; ) {
E first = q.peek();
if (first == null) available.await();
else {
long delay = first.getDelay(TimeUnit.NANOSECONDS);
if (delay <= 0) return q.poll();
else if (leader != null) available.await();
else {
Thread thisThread = Thread.currentThread();
leader = thisThread;
try {
available.awaitNanos(delay);
} finally {
if (leader == thisThread) leader = null;
}
}
}
}
} finally {
if (leader == null && q.peek() != null) available.signal();
lock.unlock();
}
}
/**
* Creates an <tt>ArrayBlockingQueue</tt> with the given (fixed) capacity and the specified access
* policy.
*
* @param capacity the capacity of this queue
* @param fair if <tt>true</tt> then queue accesses for threads blocked on insertion or removal,
* are processed in FIFO order; if <tt>false</tt> the access order is unspecified.
* @throws IllegalArgumentException if <tt>capacity</tt> is less than 1
*/
public ArrayBlockingQueue(int capacity, boolean fair) {
if (capacity <= 0) throw new IllegalArgumentException();
this.items = (E[]) new Object[capacity];
lock = new ReentrantLock(fair);
notEmpty = lock.newCondition();
notFull = lock.newCondition();
}
/**
* Retrieves and removes the head of this queue, waiting if necessary until an element with an
* expired delay is available on this queue, or the specified wait time expires.
*
* @return the head of this queue, or <tt>null</tt> if the specified waiting time elapses before
* an element with an expired delay becomes available
* @throws InterruptedException {@inheritDoc}
*/
public E poll(long timeout, TimeUnit unit) throws InterruptedException {
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
for (; ; ) {
E first = q.peek();
if (first == null) {
if (nanos <= 0) return null;
else nanos = available.awaitNanos(nanos);
} else {
long delay = first.getDelay(TimeUnit.NANOSECONDS);
if (delay <= 0) return q.poll();
if (nanos <= 0) return null;
if (nanos < delay || leader != null) nanos = available.awaitNanos(nanos);
else {
Thread thisThread = Thread.currentThread();
leader = thisThread;
try {
long timeLeft = available.awaitNanos(delay);
nanos -= delay - timeLeft;
} finally {
if (leader == thisThread) leader = null;
}
}
}
}
} finally {
if (leader == null && q.peek() != null) available.signal();
lock.unlock();
}
}
/**
* Retrieves and removes the head of this queue, waiting if necessary until an element with an
* expired delay is available on this queue, or the specified wait time expires.
*
* @return the head of this queue, or <tt>null</tt> if the specified waiting time elapses before
* an element with an expired delay becomes available
* @throws InterruptedException {@inheritDoc}
*/
public E poll(long timeout, TimeUnit unit) throws InterruptedException {
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
for (; ; ) {
E first = q.peek();
if (first == null) {
if (nanos <= 0) return null;
else nanos = available.awaitNanos(nanos);
} else {
long delay = first.getDelay(TimeUnit.NANOSECONDS);
if (delay > 0) {
if (nanos <= 0) return null;
if (delay > nanos) delay = nanos;
long timeLeft = available.awaitNanos(delay);
nanos -= delay - timeLeft;
} else {
E x = q.poll();
assert x != null;
if (q.size() != 0) available.signalAll();
return x;
}
}
}
} finally {
lock.unlock();
}
}
/**
* @throws UnsupportedOperationException {@inheritDoc}
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @throws IllegalArgumentException {@inheritDoc}
*/
public int drainTo(Collection<? super E> c, int maxElements) {
if (c == null) throw new NullPointerException();
if (c == this) throw new IllegalArgumentException();
if (maxElements <= 0) return 0;
final E[] items = this.items;
final ReentrantLock lock = this.lock;
lock.lock();
try {
int i = takeIndex;
int n = 0;
int sz = count;
int max = (maxElements < count) ? maxElements : count;
while (n < max) {
c.add(items[i]);
items[i] = null;
i = inc(i);
++n;
}
if (n > 0) {
count -= n;
takeIndex = i;
notFull.signalAll();
}
return n;
} finally {
lock.unlock();
}
}
public void run() {
cerrojo.lock();
try { // ... cuerpo del metodo en e.m.
} finally {
cerrojo.unlock();
}
}
public void untimed() {
boolean captured = lock.tryLock();
try {
System.out.println("tryLock(): " + captured);
} finally {
if (captured) lock.unlock();
}
}
/**
* Removes a single instance of the specified element from this queue, if it is present, whether
* or not it has expired.
*/
public boolean remove(Object o) {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return q.remove(o);
} finally {
lock.unlock();
}
}
public static void main(String[] args) throws Throwable {
final ReentrantLock lock = new ReentrantLock();
lock.lock();
final ReentrantReadWriteLock rwlock = new ReentrantReadWriteLock();
final ReentrantReadWriteLock.ReadLock readLock = rwlock.readLock();
final ReentrantReadWriteLock.WriteLock writeLock = rwlock.writeLock();
rwlock.writeLock().lock();
final BlockingQueue<Object> q = new LinkedBlockingQueue<Object>();
final Semaphore fairSem = new Semaphore(0, true);
final Semaphore unfairSem = new Semaphore(0, false);
// final int threads =
// rnd.nextInt(Runtime.getRuntime().availableProcessors() + 1) + 1;
final int threads = 3;
// On Linux, this test runs very slowly for some reason,
// so use a smaller number of iterations.
// Solaris can handle 1 << 18.
// On the other hand, jmap is much slower on Solaris...
final int iterations = 1 << 8;
final CyclicBarrier cb = new CyclicBarrier(threads + 1);
for (int i = 0; i < threads; i++)
new Thread() {
public void run() {
try {
final Random rnd = new Random();
for (int j = 0; j < iterations; j++) {
if (j == iterations / 10 || j == iterations - 1) {
cb.await(); // Quiesce
cb.await(); // Resume
}
// int t = rnd.nextInt(2000);
int t = rnd.nextInt(900);
check(!lock.tryLock(t, NANOSECONDS));
check(!readLock.tryLock(t, NANOSECONDS));
check(!writeLock.tryLock(t, NANOSECONDS));
equal(null, q.poll(t, NANOSECONDS));
check(!fairSem.tryAcquire(t, NANOSECONDS));
check(!unfairSem.tryAcquire(t, NANOSECONDS));
}
} catch (Throwable t) {
unexpected(t);
}
}
}.start();
cb.await(); // Quiesce
rendezvousChild(); // Measure
cb.await(); // Resume
cb.await(); // Quiesce
rendezvousChild(); // Measure
cb.await(); // Resume
System.exit(failed);
}
/**
* Atomically removes all of the elements from this delay queue. The queue will be empty after
* this call returns. Elements with an unexpired delay are not waited for; they are simply
* discarded from the queue.
*/
public void clear() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
q.clear();
} finally {
lock.unlock();
}
}
public int size() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return q.size();
} finally {
lock.unlock();
}
}
public E peek() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return (count == 0) ? null : items[takeIndex];
} finally {
lock.unlock();
}
}
public String toString() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return super.toString();
} finally {
lock.unlock();
}
}
/**
* Retrieves, but does not remove, the head of this queue, or returns <tt>null</tt> if this queue
* is empty. Unlike <tt>poll</tt>, if no expired elements are available in the queue, this method
* returns the element that will expire next, if one exists.
*
* @return the head of this queue, or <tt>null</tt> if this queue is empty.
*/
public E peek() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return q.peek();
} finally {
lock.unlock();
}
}
/**
* Returns an iterator over the elements in this queue in proper sequence. The returned
* <tt>Iterator</tt> is a "weakly consistent" iterator that will never throw {@link
* ConcurrentModificationException}, and guarantees to traverse elements as they existed upon
* construction of the iterator, and may (but is not guaranteed to) reflect any modifications
* subsequent to construction.
*
* @return an iterator over the elements in this queue in proper sequence
*/
public Iterator<E> iterator() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return new Itr();
} finally {
lock.unlock();
}
}
/**
* Returns the number of additional elements that this queue can ideally (in the absence of memory
* or resource constraints) accept without blocking. This is always equal to the initial capacity
* of this queue less the current <tt>size</tt> of this queue.
*
* <p>Note that you <em>cannot</em> always tell if an attempt to insert an element will succeed by
* inspecting <tt>remainingCapacity</tt> because it may be the case that another thread is about
* to insert or remove an element.
*/
public int remainingCapacity() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return items.length - count;
} finally {
lock.unlock();
}
}
/**
* Returns an array containing all of the elements in this queue. The returned array elements are
* in no particular order.
*
* <p>The returned array will be "safe" in that no references to it are maintained by this queue.
* (In other words, this method must allocate a new array). The caller is thus free to modify the
* returned array.
*
* <p>This method acts as bridge between array-based and collection-based APIs.
*
* @return an array containing all of the elements in this queue
*/
public Object[] toArray() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return q.toArray();
} finally {
lock.unlock();
}
}
/**
* Returns an array containing all of the elements in this queue; the runtime type of the returned
* array is that of the specified array. The returned array elements are in no particular order.
* If the queue fits in the specified array, it is returned therein. Otherwise, a new array is
* allocated with the runtime type of the specified array and the size of this queue.
*
* <p>If this queue fits in the specified array with room to spare (i.e., the array has more
* elements than this queue), the element in the array immediately following the end of the queue
* is set to <tt>null</tt>.
*
* <p>Like the {@link #toArray()} method, this method acts as bridge between array-based and
* collection-based APIs. Further, this method allows precise control over the runtime type of the
* output array, and may, under certain circumstances, be used to save allocation costs.
*
* <p>The following code can be used to dump a delay queue into a newly allocated array of
* <tt>Delayed</tt>:
*
* <pre>
* Delayed[] a = q.toArray(new Delayed[0]);</pre>
*
* Note that <tt>toArray(new Object[0])</tt> is identical in function to <tt>toArray()</tt>.
*
* @param a the array into which the elements of the queue are to be stored, if it is big enough;
* otherwise, a new array of the same runtime type is allocated for this purpose
* @return an array containing all of the elements in this queue
* @throws ArrayStoreException if the runtime type of the specified array is not a supertype of
* the runtime type of every element in this queue
* @throws NullPointerException if the specified array is null
*/
public <T> T[] toArray(T[] a) {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return q.toArray(a);
} finally {
lock.unlock();
}
}
/**
* Retrieves and removes the head of this queue, or returns <tt>null</tt> if this queue has no
* elements with an expired delay.
*
* @return the head of this queue, or <tt>null</tt> if this queue has no elements with an expired
* delay
*/
public E poll() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
E first = q.peek();
if (first == null || first.getDelay(TimeUnit.NANOSECONDS) > 0) return null;
else return q.poll();
} finally {
lock.unlock();
}
}
public E poll() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
if (count == 0) return null;
E x = extract();
return x;
} finally {
lock.unlock();
}
}
/**
* Inserts the specified element into this delay queue.
*
* @param e the element to add
* @return <tt>true</tt>
* @throws NullPointerException if the specified element is null
*/
public boolean offer(E e) {
final ReentrantLock lock = this.lock;
lock.lock();
try {
E first = q.peek();
q.offer(e);
if (first == null || e.compareTo(first) < 0) available.signalAll();
return true;
} finally {
lock.unlock();
}
}
public void timed() {
boolean captured = false;
try {
captured = lock.tryLock(2, TimeUnit.SECONDS);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
try {
System.out.println("tryLock(2, TimeUnit.SECONDS): " + captured);
} finally {
if (captured) lock.unlock();
}
}
/**
* Inserts the specified element into this delay queue.
*
* @param e the element to add
* @return <tt>true</tt>
* @throws NullPointerException if the specified element is null
*/
public boolean offer(E e) {
final ReentrantLock lock = this.lock;
lock.lock();
try {
q.offer(e);
if (q.peek() == e) {
leader = null;
available.signal();
}
return true;
} finally {
lock.unlock();
}
}
public E next() {
final ReentrantLock lock = ArrayBlockingQueue.this.lock;
lock.lock();
try {
if (nextIndex < 0) throw new NoSuchElementException();
lastRet = nextIndex;
E x = nextItem;
nextIndex = inc(nextIndex);
checkNext();
return x;
} finally {
lock.unlock();
}
}
/**
* Inserts the specified element at the tail of this queue if it is possible to do so immediately
* without exceeding the queue's capacity, returning <tt>true</tt> upon success and <tt>false</tt>
* if this queue is full. This method is generally preferable to method {@link #add}, which can
* fail to insert an element only by throwing an exception.
*
* @throws NullPointerException if the specified element is null
*/
public boolean offer(E e) {
if (e == null) throw new NullPointerException();
final ReentrantLock lock = this.lock;
lock.lock();
try {
if (count == items.length) return false;
else {
insert(e);
return true;
}
} finally {
lock.unlock();
}
}
@Override
public void setChainHead(StoredBlock chainHead) throws BlockStoreException {
final MappedByteBuffer buffer = this.buffer;
if (buffer == null) throw new BlockStoreException("Store closed");
lock.lock();
try {
lastChainHead = chainHead;
byte[] headHash = chainHead.getHeader().getHash().getBytes();
buffer.position(8);
buffer.put(headHash);
} finally {
lock.unlock();
}
}
/**
* Retrieves and removes the head of this queue, or returns <tt>null</tt> if this queue has no
* elements with an expired delay.
*
* @return the head of this queue, or <tt>null</tt> if this queue has no elements with an expired
* delay
*/
public E poll() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
E first = q.peek();
if (first == null || first.getDelay(TimeUnit.NANOSECONDS) > 0) return null;
else {
E x = q.poll();
assert x != null;
if (q.size() != 0) available.signalAll();
return x;
}
} finally {
lock.unlock();
}
}
public final Object call() throws Exception {
barrier.await();
int sum = v;
int x = 0;
int n = ITERS;
while (n-- > 0) {
lock.lockInterruptibly();
try {
v = x = LoopHelpers.compute1(v);
} finally {
lock.unlock();
}
sum += LoopHelpers.compute2(LoopHelpers.compute2(x));
}
return new Integer(sum);
}
private void initNewStore(NetworkParameters params) throws Exception {
byte[] header;
header = HEADER_MAGIC.getBytes("US-ASCII");
buffer.put(header);
// Insert the genesis block.
lock.lock();
try {
setRingCursor(buffer, FILE_PROLOGUE_BYTES);
} finally {
lock.unlock();
}
Block genesis = params.getGenesisBlock().cloneAsHeader();
StoredBlock storedGenesis = new StoredBlock(genesis, genesis.getWork(), 0);
put(storedGenesis);
setChainHead(storedGenesis);
}
public E take() throws InterruptedException {
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
try {
while (count == 0) notEmpty.await();
} catch (InterruptedException ie) {
notEmpty.signal(); // propagate to non-interrupted thread
throw ie;
}
E x = extract();
return x;
} finally {
lock.unlock();
}
}
