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19d954c76c
In order to implement GSO in `connlib`, we opted for an approach where packets of the same length are being appended to a buffer. Each of these buffers is the sent to the kernel in a single syscall, which drastically decreases the per-packet overhead of syscalls and therefore improves performance. Within `connlib` itself, we prioritise control-protocol associated packets over tunnel traffic. The idea here is that even under high-load, we want to ensure that STUN probes between the peers and to the relays are sent in a timely manner. Failing to send these probes results in a false-positive detection of a lost connection because the `connlib`'s internal state uses timeouts to detect such situations. Despite processing the packets itself in a timely manner, it is still possible that they get delayed depending on which order the get flushed to the socket. This order is currently non-deterministic because `GsoQueue` uses a `HashMap` internally and when accessing the batched-together datagrams, we just access it via `iter_mut`. To fix this, we use a `BTreeMap` instead and explicitly define the `Key` to start with the `segment_size` field. As a result, entries within the `BTreeMap` will be sorted ascending by `segment_size` (i.e. the size of individual packets within the batch). Packets of smaller size are more likely to be control messages like STUN binding requests or TURN messages to the relays for managing allocations. By sorting the map explicitly, we ensure that if the UDP socket is ready to send, we flush out these messages first before moving on to bigger packets such as the ones containing (more likely) WireGuard data messages.
11 lines
1.1 KiB
TOML
11 lines
1.1 KiB
TOML
avoid-breaking-exported-api = false # We don't publish anything to crates.io, hence we don't need to worry about breaking Rust API changes.
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disallowed-methods = [
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{ path = "std::collections::HashMap::iter", reason = "HashMap has non-deterministic iteration order, use BTreeMap instead" },
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{ path = "std::collections::HashSet::iter", reason = "HashSet has non-deterministic iteration order, use BTreeSet instead" },
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{ path = "std::collections::HashMap::iter_mut", reason = "HashMap has non-deterministic iteration order, use BTreeMap instead" },
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{ path = "std::collections::HashSet::iter_mut", reason = "HashSet has non-deterministic iteration order, use BTreeSet instead" },
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{ path = "std::collections::HashMap::into_iter", reason = "HashMap has non-deterministic iteration order, use BTreeMap instead" },
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{ path = "std::collections::HashSet::into_iter", reason = "HashSet has non-deterministic iteration order, use BTreeSet instead" },
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{ path = "tracing::subscriber::set_global_default", reason = "Does not init `LogTracer`, use `firezone_logging::init` instead." },
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]
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