Fix Routing Table Refresh after we have a SearchByKadId RPC

[aarshkshah1992]

We should have a SearchByKadId RPC which allows us to search for a key in the network using it's DHT Id in the XOR space and then revisit how we refresh the Routing Table/have better tests.

TODO

• [ ] Have a SearchByKadId RPC.

• [ ] Rewrite the refresh logic in DHT & Routing Table to use the new RPC.

• [ ] Remove the GenRandPeerId in go-libp2p-kbucket function which can ONLY produce upto maxCpls.

• [x] Stop refreshing once we stop filling buckets because we are searching for CPLs that might not even have peers in the network. (https://github.com/libp2p/go-libp2p-kad-dht/issues/550) PR at https://github.com/libp2p/go-libp2p-kad-dht/pull/601.

• [ ] Have a solid integration test and a TestGround that ensures the Refresh works correctly.

Also,

Nice to have:

• [x] Collapse empty buckets to make the state easy to reason about (https://github.com/libp2p/go-libp2p-kbucket/issues/72). PR at: https://github.com/libp2p/go-libp2p-kbucket/pull/77.

• [x] Test refreshes on an empty RT returns an appropriate error https://github.com/libp2p/go-libp2p-kad-dht/issues/555. PR at https://github.com/libp2p/go-libp2p-kad-dht/pull/601.

[aarshkshah1992]

@Stebalien @aschmahmann.

[aschmahmann]

Thanks for filing the issue on this, I thought we'd already filed this when we first hacked in the GenRandPeerID function but I guess not.

Worth noting that the outlier here isn't really the bucket refreshing but the FindPeer RPC. Tagging https://github.com/libp2p/go-libp2p/issues/784 as a reminder.

[aarshkshah1992]

@aschmahmann I am not sure what you mean.

I understand that the GetClosestPeers RPC needs to take a kadId and move away from using the FindPeer RPC. However, how is the FindPeer issue linked to what we are trying to do here ?

[aarshkshah1992]

@jacobheun For the 0.6 milestone.