private static String lock(String lock) {
String realPath = "";
String parent = "/lock";
String lockName = parent + "/" + lock;
logger.debug("Getting lock " + lockName);
try {
if (zkInstance.exists(parent, false) == null)
zkInstance.create(parent, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.fromFlag(0));
} catch (Exception E) {
logger.error("Error creating lock node: " + E.toString());
return null;
}
List<String> children = new LinkedList<String>();
try {
// List <ACL> ACLList = zkInstance.getACL(lockName, zkInstance.exists(lock, false));
realPath =
zkInstance.create(
lockName, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
// children = zkInstance.getChildren(realPath, false);
checkLock:
while (true) {
children = zkInstance.getChildren(parent, false);
for (String curChild : children) {
String child = parent + "/" + curChild;
// System.out.println(child + " " + realPath + " " +
// Integer.toString(child.compareTo(realPath)));
if (child.compareTo(realPath) < 0
&& child.length() == realPath.length()
&& curChild.startsWith(lock)) {
// System.out.println(child + " cmp to " + realPath);
Thread.sleep(300);
continue checkLock;
}
}
logger.info("Got lock " + lockName);
return realPath;
}
} catch (Exception E) {
logger.error("Exception while trying to get lock " + lockName + " :" + E.toString());
E.printStackTrace();
return null;
}
}
private static boolean unlock(String lock) {
logger.info("Releasing lock " + lock);
try {
zkInstance.delete(lock, -1);
} catch (Exception E) {
logger.debug("Error releasing lock: " + E.toString());
return true;
}
return true;
}