b3746b330f
Correctly implementing asynchronous IO is notoriously hard. In order to not drop packets in the process, one has to ensure a given socket is ready to accept packets, buffer them if it is not case, suspend everything else until the socket is ready and then continue. Until now, we did this because it was the only option to run the UDP sockets on the same thread as the actual packet processing. That in turn was motivated by wanting to pass around references of the received packets for processing. Rust's borrow-checker does not allow to pass references between threads which forced us to have the sockets on the same thread as the packet processing. Like we already did in other places in `connlib`, this can be solved through the use of buffer pools. Using a buffer pool, we can use heap allocations to store the received packets without having to make a new allocation every time we read new packets. Instead, we can have a dedicated thread that is connected to `connlib`'s packet processing thread via two channels (one for inbound and one for outbound packets). These channels are bounded, which ensures backpressure is maintained in case one of the two threads lags behind. These bounds also mean that we have at most N buffers from the buffer pool in-flight (where N is the capacity of the channel). Within those dedicated threads, we can then use `async/await` notation to suspend the entire task when a socket isn't ready for sending. Resolves: #8000
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.