/**
* @throws KeeperException
* @throws InterruptedException
* @throws NoSuchElementException
*/
protected byte[] getNext(boolean waitForElement, boolean deleteElement)
throws KeeperException, InterruptedException, NoSuchElementException {
TreeMap<KEY, String> orderedChildren;
// element, take, and remove follow the same pattern.
// We want to return the child node with the smallest sequence number.
// Since other clients are remove()ing and take()ing nodes concurrently,
// the child with the smallest sequence number in orderedChildren might
// be gone by the time we check.
// We don't call getChildren again until we have tried the rest of the
// nodes in sequence order,
// BUT if the children change with a higher priority
// than the current child we are getting, then we reload all the
// children.
while (true) {
PriorityLatchChildWatcher childWatcher = new PriorityLatchChildWatcher();
try {
orderedChildren = orderedChildren(childWatcher);
} catch (KeeperException.NoNodeException e) {
if (waitForElement) {
zookeeper.create(dir, new byte[0], acl, CreateMode.PERSISTENT);
continue;
} else {
throw new NoSuchElementException();
}
}
if (orderedChildren.size() == 0) {
if (waitForElement) {
childWatcher.awaitChange();
continue;
} else {
throw new NoSuchElementException();
}
}
for (String headNode : orderedChildren.values()) {
String path = dir + "/" + headNode;
try {
byte[] data = zookeeper.getData(path, false, null);
if (childWatcher.hasChangedHigherThan(keyHandler.getPriority(headNode))) {
break;
}
if (deleteElement) {
zookeeper.delete(path, -1);
}
return data;
} catch (KeeperException.NoNodeException e) {
// Another client deleted the node first.
}
}
} // while loop end
}
