go-ipfs should measure peer latency from more subsystems than just the DHT

[MichaelMure]

Version information:

go-ipfs version: 0.4.19-
Repo version: 7
System version: amd64/linux
Golang version: go1.11.5

Type: enhancement

Description:

Currently, go-ipfs records peer latencies (peerstore.Metrics.RecordLatency(peer.ID, time.Duration)) from only two sources:

• user triggered ping using ipfs ping <peer>
• DHT requests (message that will lead to a response, not one off)

This situation lead to ipfs swarm peers --latency getting filled by peers with n/a latencies, because no latencies has ever been recorded for them. I expect that also leads to some bad decision when the connection manager has to drop some of them.

My point is, go-ipfs should record latencies from more subsystem. Maybe bitswap ?

[Stebalien]

Currently, we only use latencies when making decisions in the DHT but I agree we should measure latencies in more places. Bitswap is hard because peers don't send blocks immediately, they put the user in a queue.