Watcher guarantees

2009-02-13 Thread Tom White
If client sets a watcher on a znode by doing a getData operation is it guaranteed to get the next change after the value it read, or can a change be missed? In other words if the value it read had zxid z1 and the next update of the znode has zxid z2, will the watcher always get the event for the

Re: Watcher guarantees

2009-02-13 Thread Patrick Hunt
Tom White wrote: If client sets a watcher on a znode by doing a getData operation is it guaranteed to get the next change after the value it read, or can a change be missed? In other words if the value it read had zxid z1 and the next update of the znode has zxid z2, will the watcher always

Re: Watcher guarantees

2009-02-13 Thread Mahadev Konar
If client sets a watcher on a znode by doing a getData operation is it guaranteed to get the next change after the value it read, or can a change be missed? The watch is just a notification that the node changed. If you do a getData on the node, you their might have been more updates on the

Re: Watcher guarantees

2009-02-13 Thread Tom White
Thanks for your answers. I understand that you have to call getData() to find the value of the znode, and that it may have been updated between the watcher being called and the getData() call. So in that sense you can miss updates. But watches have strong enough guarantees to allow you to keep up

[ANNOUNCE] Apache ZooKeeper 3.1.0

2009-02-13 Thread Patrick Hunt
The Apache ZooKeeper team is proud to announce Apache ZooKeeper version 3.1.0. ZooKeeper is a high-performance coordination service for distributed applications. It exposes common services - such as naming, configuration management, synchronization, and group services - in a simple interface