org.apache.curator.framework.api

Interface ProtectACLCreateModePathAndBytesable<T>

All Superinterfaces:

ACLable<BackgroundPathAndBytesable<T>>, ACLBackgroundPathAndBytesable<T>, Backgroundable<PathAndBytesable<T>>, BackgroundPathAndBytesable<T>, CreateModable<ACLBackgroundPathAndBytesable<T>>, PathAndBytesable<T>

public interface ProtectACLCreateModePathAndBytesable<T>
extends ACLBackgroundPathAndBytesable<T>, CreateModable<ACLBackgroundPathAndBytesable<T>>

Method Summary

Methods

Modifier and Type	Method and Description
ACLCreateModeBackgroundPathAndBytesable<String>	withProtection() Hat-tip to https://github.com/sbridges for pointing this out

Methods inherited from interface org.apache.curator.framework.api.ACLable

withACL

Methods inherited from interface org.apache.curator.framework.api.Backgroundable

inBackground, inBackground, inBackground, inBackground, inBackground, inBackground

Methods inherited from interface org.apache.curator.framework.api.PathAndBytesable

forPath, forPath

Methods inherited from interface org.apache.curator.framework.api.CreateModable

withMode

Method Detail

withProtection

ACLCreateModeBackgroundPathAndBytesable<String> withProtection()

Hat-tip to https://github.com/sbridges for pointing this out

It turns out there is an edge case that exists when creating sequential-ephemeral nodes. The creation can succeed on the server, but the server can crash before the created node name is returned to the client. However, the ZK session is still valid so the ephemeral node is not deleted. Thus, there is no way for the client to determine what node was created for them.

Even without sequential-ephemeral, however, the create can succeed on the sever but the client (for various reasons) will not know it.

Putting the create builder into protection mode works around this. The name of the node that is created is prefixed with a GUID. If node creation fails the normal retry mechanism will occur. On the retry, the parent path is first searched for a node that has the GUID in it. If that node is found, it is assumed to be the lost node that was successfully created on the first try and is returned to the caller.

Returns:

this