/**
* Return the stat of the node of the given path. Return null if no such a node exists.
*
* <p>If the watch is non-null and the call is successful (no exception is thrown), a watch will
* be left on the node with the given path. The watch will be triggered by a successful operation
* that creates/delete the node or sets the data on the node.
*
* @param path the node path
* @param watcher explicit watcher
* @return the stat of the node of the given path; return null if no such a node exists.
* @throws KeeperException If the server signals an error
* @throws InterruptedException If the server transaction is interrupted.
* @throws IllegalArgumentException if an invalid path is specified
*/
public Stat exists(final String path, Watcher watcher)
throws KeeperException, InterruptedException {
final String clientPath = path;
PathUtils.validatePath(clientPath);
// the watch contains the un-chroot path
WatchRegistration wcb = null;
if (watcher != null) {
wcb = new ExistsWatchRegistration(watcher, clientPath);
}
final String serverPath = prependChroot(clientPath);
RequestHeader h = new RequestHeader();
h.setType(ZooDefs.OpCode.exists);
ExistsRequest request = new ExistsRequest();
request.setPath(serverPath);
request.setWatch(watcher != null);
SetDataResponse response = new SetDataResponse();
ReplyHeader r = cnxn.submitRequest(h, request, response, wcb);
if (r.getErr() != 0) {
if (r.getErr() == KeeperException.Code.NONODE.intValue()) {
return null;
}
throw KeeperException.create(KeeperException.Code.get(r.getErr()), clientPath);
}
return response.getStat().getCzxid() == -1 ? null : response.getStat();
}
@Override
protected boolean shouldAddWatch(int rc) {
return rc == 0 || rc == KeeperException.Code.NONODE.intValue();
}