Skip to content

Gossip Support

Gossip support is a short subsystem that cares about handling active leaves and network bridge update events.

Functionalities

  • Check connectivity: The subsystem contains a timer that triggers every 600 seconds (10 minutes) a connectivity check that is a simple verification on the amount of authorities connected against the actual set of authorities, if the percentage of connected authorities is bellow 90% the node will issue WARN logs.

  • Handle Active Leaves:

  • Given the current values in the state, last failure and last connection request, the subsystem should force new requests or re-resolve authorities
  • Determine if the current session index has changed, if so determine relevant validators and issue connection request. The subsystem should change the last sesison index value only if it is possible to retrieve the new session info.

  • If we notice that a new session is starting we should update our authority ids cache and send a NetworkBridgeRxMessage::UpdatedAuthorityIds message with informations about the new set of authorities.

  • Handle Network Bridge Update:

  • In the above point, when handling active leaves, we issue connection requests and whenever a new connection is stablished or a disconnection happens for some reason. The subsytems listen on any network bridge update about NetworkBridgeEvent::PeerConnected and NetworkBridgeEvent::PeerDisconnected, other updates are not important.

State

The subsystem state is composed of:

  • Keystore
  • Last Session Index
  • Last Failure: last time we could not resolve a third of the authorities
  • Last Connection Request: is possible that validators change their peer IDs in during a session. If that happens we will reconnect to them in the best case after a session, so we need to try more often to resolve peers and reconnect to them. We cannot detect changes faster them Authority Discovery DHT queries.
  • Failure Start: first time the node cannot reach the connectivity threshold
  • Resolved Authorities: A map of resolved authority IDs to a set of multiaddr, basically we were able to find the addresses for authorities, not mean we are actually connected to them.
  • Connected Authorities: A map of actual authorities ID's connected to their PeerId
  • Connected Peers: A map of PeerId to authority IDs for fast lookup
  • Authority Discovery: authority discovery service, allows us to resolve authorities addresses.