8e0f00a3a6
At present, the relay's event-loop simply drops a UDP packet in case the socket is not ready for writing. This is terrible for throughput because it means the encapsulated packet within the WG payload needs to be retransmitted by the source after a timeout. To avoid this, we instead buffer the packet and suspend the event loop until it has been correctly flushed out. This may still cause packet loss because the receive buffer may overflow in the meantime. However, there is nothing we can do about that because UDP itself doesn't have any backpressure. The relay listens on many sockets at once via a separate worker thread and an `mio` event-loop. In addition to the current subscription to readable event, we now also subscribe to writable events. At the very top of the relay's event-loop, we insert a `flush` function that ensures all buffered packets have been written out and - in case writing a packet fails - suspends the event-loop with a waker. If we receive a new event for write-readiness, we wake the waker which will trigger a new call to `Eventloop::poll` where we again try to flush the pending packet. We don't bother with tracking exactly, which socket sent the write-readiness and which socket we have still pending packets in. Instead, we suspend the entire event-loop until all pending packets have been flushed. Resolves: #7519.
Rust development guide
Firezone uses Rust for all data plane components. This directory contains the Linux and Windows clients, and low-level networking implementations related to STUN/TURN.
We target the last stable release of Rust using rust-toolchain.toml.
If you are using rustup, that is automatically handled for you.
Otherwise, ensure you have the latest stable version of Rust installed.
Reading Client logs
The Client logs are written as JSONL for machine-readability.
To make them more human-friendly, pipe them through jq like this:
cd path/to/logs # e.g. `$HOME/.cache/dev.firezone.client/data/logs` on Linux
cat *.log | jq -r '"\(.time) \(.severity) \(.message)"'
Resulting in, e.g.
2024-04-01T18:25:47.237661392Z INFO started log
2024-04-01T18:25:47.238193266Z INFO GIT_VERSION = 1.0.0-pre.11-35-gcc0d43531
2024-04-01T18:25:48.295243016Z INFO No token / actor_name on disk, starting in signed-out state
2024-04-01T18:25:48.295360641Z INFO null
Benchmarking on Linux
The recommended way for benchmarking any of the Rust components is Linux' perf utility.
For example, to attach to a running application, do:
- Ensure the binary you are profiling is compiled with the
releaseprofile. sudo perf record -g --freq 10000 --pid $(pgrep <your-binary>).- Run the speed test or whatever load-inducing task you want to measure.
sudo perf script > profile.perf- Open profiler.firefox.com and load
profile.perf
Instead of attaching to a process with --pid, you can also specify the path to executable directly.
That is useful if you want to capture perf data for a test or a micro-benchmark.