96170be082
In #8159, we introduced a regression that could lead to a deadlock when shutting down the TUN device. Whilst we did close the channel prior to awaiting the thread to exit, we failed to notice that _another_ instance of the sender could be alive as part of an internally stored "sending permit" with the `PollSender` in case another packet is queued for sending. We need to explicitly call `abort_send` to free that. Judging from the comment and a prior bug, this shutdown logic has been buggy before. To further avoid this deadlock, we introduce two changes: - The worker threads only receive a `Weak` reference to the `wintun::Session` - We move all device-related state into a dedicated `TunState` struct that we can drop prior to joining the threads The combination of these features means that all strong references to channels and the session are definitely dropped without having to wait for anything. To provide a clean and synchronous shutdown, we wait for at most 5s on the worker-threads. If they don't exit until then, we log a warning and exit anyway. This should greatly reduce the risk of future bugs here because the session (and thus the WinTUN device) gets shutdown in any case and so at worst, we have a few zombie threads around. Resolves: #8265
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.