Max Inden d4f8ec2d48
misc/metrics: Track # connected nodes supporting specific protocol (#2734)
* misc/metrics: Explicitly delegate event recording to each recorder

This allows delegating a single event to multiple `Recorder`s. That enables e.g. the
`identify::Metrics` `Recorder` to act both on `IdentifyEvent` and `SwarmEvent`. The latter enables
it to garbage collect per peer data on disconnects.

* protocols/dcutr: Expose PROTOCOL_NAME

* protocols/identify: Expose PROTOCOL_NAME and PUSH_PROTOCOL_NAME

* protocols/ping: Expose PROTOCOL_NAME

* protocols/relay: Expose HOP_PROTOCOL_NAME and STOP_PROTOCOL_NAME

* misc/metrics: Track # connected nodes supporting specific protocol

An example metric exposed with this patch:

```
libp2p_identify_protocols{protocol="/ipfs/ping/1.0.0"} 10
```

This implies that 10 of the currently connected nodes support the ping protocol.
2022-07-15 09:16:03 +02:00
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