Method start_query

ipld/resolver/src/service.rs:474–507

Start a CID resolution.

(&mut self, cid: Cid, subnet_id: SubnetID, response_channel: ResponseChannel)

    /// Start a CID resolution.
    fn start_query(&mut self, cid: Cid, subnet_id: SubnetID, response_channel: ResponseChannel) {
        let mut peers = self.membership_mut().providers_of_subnet(&subnet_id);

        stats::CONTENT_RESOLVE_PEERS.observe(peers.len() as f64);

        if peers.is_empty() {
            stats::CONTENT_RESOLVE_NO_PEERS.inc();
            send_resolve_result(response_channel, Err(anyhow!(NoKnownPeers(subnet_id))));
        } else {
            // Connect to them in a random order, so as not to overwhelm any specific peer.
            peers.shuffle(&mut rand::thread_rng());

            // Prioritize peers we already have an established connection with.
            let (connected, known) = peers
                .into_iter()
                .partition::<Vec<_>, _>(|id| self.swarm.is_connected(id));

            stats::CONTENT_CONNECTED_PEERS.observe(connected.len() as f64);

            let peers = [connected, known].into_iter().flatten().collect();
            let (peers, fallback) = self.split_peers_for_query(peers);

            let query = Query {
                cid,
                subnet_id,
                response_channel,
                fallback_peer_ids: fallback,
            };

            let query_id = self.content_mut().resolve(cid, peers);

            self.queries.insert(query_id, query);
        }
    }

    /// Handle the results from a resolve attempt. If it succeeded, notify the
    /// listener. Otherwise if we have fallback peers to try, start another