As far as I can tell, the "under construction" approach will let me do
everything I need! Thanks - that is a simple and elegant approach that
I probably should have known about, at least I know now....
On 5/18/2012 8:03 PM, Ted Dunning wrote:
On Fri, May 18, 2012 at 1:55 PM, Joe Gamache<[email protected]>wrote:
...
I have a one process that is trying to create some "work" that will be
represented via a ZNode. A large number of other processes are looking
for work. The node that represents the work will be sequential. Most
importantly, it will be incomplete until the structure below it is
completed.
That is easy. Just create the lower structures first. If the upper
structure needs to have an indicator that it is under construction, just
set a bit inside it using the atomic update method. Or create a separate
node to do leader election.
Thus, I would like to be able to create that node and lock it atomically
OR create the entire structure below it atomically.
Remember ZK doesn't do locks.
You can create the node with the "under-construction" bit set. Or you can
use a multi to create the parent and children simultaneously. You can
create the parent with references to a version in another node by getting
the version of the parent, getting the versions of the children, updating
the parent with the version specified. Retry with backoff on failure.
I would like to avoid hacking in another parallel node structure solely for
the purpose of locking (as there will be many 1000's of these created)
As you like. This can be handled pretty easily. Setting watches on the
release of a node is a bit trickier, but can be handled as well.
All I am really wondering is can Zookeeper do this? If not, I can find
alternate ways around - they just seem less elegant to me.
It can.
