If I use a ASync version of getData and implement DataCallback on the
DataMonitor, it works with a No Node in the below mentioned use case. I can
update this IF this is the correct way of doing this.
/* DataCallback */
public void processResult(int rc, String path, Object ctx, byte[] data,
Stat stat) {
boolean exists;
switch (rc) {
case Code.Ok:
exists = true;
break;
case Code.NoNode:
System.out.println("No node");
exists = false;
break;
case Code.SessionExpired:
case Code.NoAuth:
dead = true;
listener.closing(rc);
return;
default:
// Retry errors
zk.exists(znode, true, this, null);
return;
}
if (exists) {
if ((data == null && data != prevData)
|| (data != null && !Arrays.equals(prevData, data))) {
listener.exists(data);
prevData = data;
}
}
}
/* Exists Callback */
public void processResult(int rc, String path, Object ctx, Stat stat) {
boolean exists;
switch (rc) {
case Code.Ok:
exists = true;
break;
case Code.NoNode:
exists = false;
break;
case Code.SessionExpired:
case Code.NoAuth:
dead = true;
listener.closing(rc);
return;
default:
// Retry errors
zk.exists(znode, true, this, null);
return;
}
if (exists) {
try {
System.out.println("SLEEP 10 seconds");
Thread.sleep(1);
zk.getData(znode, false, this, null);
}
catch (InterruptedException ie) {
System.out.println(ie);
}
}
}
On Mon, Sep 27, 2010 at 6:56 PM, Milind Parikh wrote:
> In the explanation of the Java binding, it is mentioned "If the file (or
> znode) exists, it gets the data from the znode, and then invoke the exists()
> callback of Executor if the state has changed. Note, it doesn't have to do
> any Exception processing for the getData call because it has watches pending
> for anything that could cause an error: if the node is deleted before it
> calls ZooKeeper.getData(), the watch event set by the
> ZooKeeper.exists()triggers a callback "
>
> I read this to mean that if I insert a Thread.sleep() before the getData
> call & removed the node from the cli, somehow (magically) there would be no
> error. But of course, it does not happen
>
> Sleeps for 10 seconds
> org.apache.zookeeper.KeeperException$NoNodeException: KeeperErrorCode =
> NoNode for /zk_test
> at
> org.apache.zookeeper.KeeperException.create(KeeperException.java:102)
> at org.apache.zookeeper.KeeperException.create(KeeperException.java:42)
> at org.apache.zookeeper.ZooKeeper.getData(ZooKeeper.java:921)
> at org.apache.zookeeper.ZooKeeper.getData(ZooKeeper.java:950)
> at DataMonitor.processResult(DataMonitor.java:114)
> at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:512)
>
> Am I doing something wrong (or reading something wrong)?
>
> -- Milind
