Release node name on graceful shutdown

[CyberROFL]

Node should release its custom name (if used) on graceful shutdown, allowing it to be used immediately for another node.

[NeimadTL]

@CyberROFL , @pixcc, it seems like the name release should be done here correct ? If so, is it as easy as setting the node's name attribute to null or are there any consideration to take into account ? Also, where is the node object defined please ?

[pixcc]

@NeimadTL

In fact, there's already a pull-request here, with almost all the necessary changes. But its author hasn't made any updates for quite a long time. I'll try to ask him if he's still interested in it.

it seems like the name release should be done here correct ?

Almost, this is the process of releasing the name if the node is re-registered as serving different database. In this context subdomain, tenant and database are synonyms. The node name is formed from the prefix slot- and the sequence number of the node within the database (this number is called SlotIndex in this code). So if a node has started serving another database, it must release the slot index it occupied within the previous database, and acquire the slot index within the new database.

You can read more about this feature in docs.

If so, is it as easy as setting the node's name attribute to null or are there any consideration to take into account ?

It's actually a little more complicated than just setting the name attribute to null. It requires a new message that the compute node is going to send to the Node Broker during its graceful shutdown to release the node name. Upon receiving this message, the Node Broker will release the node name in the in-memory data structures (SlotIndexPools) and in the persistent local database. These changes will also require a feature flag, there are examples in code.

Also, where is the node object defined please ?

It is defined here.

[pixcc]

@NeimadTL

I reached the author of the pull request. He said he's interested in finishing this pull-request, there's really not much left, he's almost done.

But there are many other issues that are suitable for newcomers as well. I can help you find a task that interests you in the field of the Node Broker or database backups.

[NeimadTL]

Hey @pixcc, thank you so much for the information you've provided, I've got some reading to do !

Thanks for sharing the PR already made for this. It's nice to have it so that can (try to) understand it.

Regarding the other issues to work on, how about this one ? Otherwise feel free to mention me and/or assign me on one you feel that fits best. Thanks