feat(libp2p): track bandwidth per transport protocol stack

[mxinden]

Description

Previously one could use the with_bandwidth_logging to measure the overall bandwidth usage, only differentiated by inbound and outbound traffic.

With this commit bandwidth can be tracked per transport protocol stack (e.g. /ip4/tcp) exposed as Prometheus metrics through libp2p_metrics::BandwidthMetricTransport.

# HELP libp2p_bandwidth_bytes Bandwidth usage by direction and transport protocols.
# TYPE libp2p_bandwidth_bytes counter
# UNIT libp2p_bandwidth_bytes bytes
libp2p_bandwidth_bytes_total{protocols="/ip4/tcp",direction="Outbound"} 1352
libp2p_bandwidth_bytes_total{protocols="/ip4/tcp",direction="Inbound"} 1484

Notes & open questions

@jxs this is my suggestion on how to expose bandwidth metrics. What do you think?

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• A changelog entry has been made in the appropriate crates

[thomaseizinger]

Left a few comments but overall this is pretty exciting :)

[jxs]

this looks really nice Max! Thanks for going ahead and implement it, and thanks Thomas also reviewing

[thomaseizinger]

Nice work! Looking forward to land this :)

[mxinden]

@thomaseizinger @jxs this is ready for a full review. Thank you for the comments thus far.

[thomaseizinger]

This looks great, thank you Max!

[jxs]

Looks great Max, thanks for this!

[mxinden]

Thank you for the help!

[thomaseizinger]

@mxinden Needs rustfmt.

[mxinden]

@thomaseizinger CI catching my mistakes 🎉

Run git fetch origin master:master
From https://github.com/libp2p/rust-libp2p
 * [new branch]        master     -> master
++ jq -e -r '.packages[] | select(.name == "libp2p-metrics") | .manifest_path'
++ cargo metadata --format-version=1 --no-deps
+ MANIFEST_PATH=/home/runner/work/rust-libp2p/rust-libp2p/misc/metrics/Cargo.toml
++ dirname /home/runner/work/rust-libp2p/rust-libp2p/misc/metrics/Cargo.toml
+ DIR_TO_CRATE=/home/runner/work/rust-libp2p/rust-libp2p/misc/metrics
++ git merge-base d9b6d7dca4c87ad37d4d569d852a360b5d408abd master
+ MERGE_BASE=9ab0e6f0fea3382607c72fc1c9086786ff541d98
++ git diff d9b6d7dca4c87ad37d4d569d852a360b5d408abd..9ab0e6f0fea3382607c72fc1c9086786ff541d98 --name-status -- /home/runner/work/rust-libp2p/rust-libp2p/misc/metrics/src /home/runner/work/rust-libp2p/rust-libp2p/misc/metrics/Cargo.toml
+ SRC_DIFF_TO_BASE='M	misc/metrics/Cargo.toml
D	misc/metrics/src/bandwidth.rs
M	misc/metrics/src/lib.rs'
++ git diff d9b6d7dca4c87ad37d4d569d852a360b5d408abd..9ab0e6f0fea3382607c72fc1c9086786ff541d98 --name-only -- /home/runner/work/rust-libp2p/rust-libp2p/misc/metrics/CHANGELOG.md
+ CHANGELOG_DIFF=misc/metrics/CHANGELOG.md
++ awk '-F ' '/^## [0-9]+\.[0-9]+\.[0-9]+/{print $2; exit}' /home/runner/work/rust-libp2p/rust-libp2p/misc/metrics/CHANGELOG.md
+ VERSION_IN_CHANGELOG=0.14.0
++ cargo metadata --format-version=1 --no-deps
++ jq -e -r '.packages[] | select(.name == "libp2p-metrics") | .version'
+ VERSION_IN_MANIFEST=0.14.0
+ [[ 0.14.0 != \0\.\1\4\.\0 ]]
+ '[' -z 'M	misc/metrics/Cargo.toml
D	misc/metrics/src/bandwidth.rs
M	misc/metrics/src/lib.rs' ']'
+ '[' -z misc/metrics/CHANGELOG.md ']'
+ git tag
+ grep -q '^libp2p-metrics-v0.14.0$'
+ echo 'v0.14.0 of '\''libp2p-metrics'\'' has already been released, please bump the version.'
v0.14.0 of 'libp2p-metrics' has already been released, please bump the version.
+ exit 1