auto-join new shards

[brenzi]

In the case of encointer, the creation of new shards is an on-chain process and we would like the workers to serve newly created shards automatically by default.

Later, it will be necessary to restrict the number of shards a worker serves - in order to scale horizontally.

See this comment

This issue should track the generic process of auto-joining shards based on on-chain actions (extrinsics or state changes)

[clangenb]

I think auto-joining is a good idea. Still, shouldn't the worker keep track on his own of the shards that exist?

Otherwise the worker would either:

• need to ask the node for all the existing shards prior to each update of shard-unspecific states, i.e., updates performed on every block as for instance in encointer.
• simply assume that alls files in the shards directory are active and update everyone of them.

[clangenb]

But I agree that id does not need to be persisted. We can just set up a global reference that keeps track of all the states during enclave runtime with a global static reference that is initialized at enclave initialization.

[brenzi]

simply assume that alls files in the shards directory are active and update everyone of them.

yes. for now

[clangenb]

I implemented this in #155 . But with the current implementation, a client could spam the worker with new shards, and the worker would always create a new one.

[brenzi]

agreed. but that's something to be solved onchain in the future (see also encointer/encointer-node#18)

[clangenb]

Ok, then I close this as fixed in #155