libp2prs-kad

Comparison of kad implementations between rust-libp2p and go-libp2p:

Kbuckets, AKA. routing table

go

• buckets are expanded on demand

• no multiaddr, depends on peerstore

• insertion:

  • initialization, to fill kbuckets with all connected peers
  • fix low peers
  • when a remote peer is sending RPC to us
  • when we iteratively query a remote peer successfully

  // TryAddPeer tries to add a peer to the Routing table. // If the peer ALREADY exists in the Routing Table and has been queried before, this call is a no-op. // If the peer ALREADY exists in the Routing Table but hasn't been queried before, we set it's LastUsefulAt value to // the current time. This needs to done because we don't mark peers as "Useful"(by setting the LastUsefulAt value) // when we first connect to them. // // If the peer is a queryPeer i.e. we queried it or it queried us, we set the LastSuccessfulOutboundQuery to the current time. // If the peer is just a peer that we connect to/it connected to us without any DHT query, we consider it as having // no LastSuccessfulOutboundQuery. // // // If the logical bucket to which the peer belongs is full and it's not the last bucket, we try to replace an existing peer // whose LastSuccessfulOutboundQuery is above the maximum allowed threshold in that bucket with the new peer. // If no such peer exists in that bucket, we do NOT add the peer to the Routing Table and return error "ErrPeerRejectedNoCapacity".

  // It returns a boolean value set to true if the peer was newly added to the Routing Table, false otherwise. // It also returns any error that occurred while adding the peer to the Routing Table. If the error is not nil, // the boolean value will ALWAYS be false i.e. the peer wont be added to the Routing Table it it's not already there. // // A return value of false with error=nil indicates that the peer ALREADY exists in the Routing Table.

• deletion

  • when a remote peer is found not responding to an outbound query
  • refresh manager: remote peer can not be connected
  • handlePeerChangeEvent: remote is deemed as not qualified as a Kad peer

rust

• all buckets are initialized in the beginning
• multiaddr embedded in kbuckets
• insertion: when Kad protocol is confirmed with remote peer -> inboung/outbound protocol upgrade done
  • insert if there is room, pending if there is not
    • KademliaBucketInserts decide how to insert: OnConnected or Manual
  • update the addresses and status if the peer is already or pending in RT
• deletion: manual only
• update: when peer is found disconnected
  • always update the addresses and status
• NoeStatus: impact how to insert a new peer into RT