mirrors/arti.git/crates/tor-proto/src/congestion/rtt.rs, branch arti-v1.4.6

proto: Make RttEstimator::{ewma,min}_rtt_usec() return `Option`.

2025-06-27T14:16:16Z

A `None` value signals to the conflux code to know to fall back on the initial RTT of the circuit. Without this change, the conflux switching logic is broken as we end up staying on the leg with the best initial RTT forever (the other leg is never picked, because its `ewma_rtt()` is stuck on `u32::MAX`, and never updated as we never send on it).

proto: Rewrite can_crosscheck_with_current_estimate for clarity.

2025-06-25T16:21:46Z

The expanded expression makes it easier to see that `can_crosscheck_with_current_estimate()` can never return `true` if `self.ewma_rtt` is `None`, and that the `expect()` from `is_clock_stalled()` cannot panic.

proto: Make RTT estimates default to None (fmt).

2025-06-25T16:21:46Z

proto: Make RTT estimates default to None.

2025-06-25T16:21:46Z

The `RttEstimator` now uses `None` to represent not-yet-measured RTTs. Previously, all the measured RTTs defaulted to 0, in contradiction with the `RttEstimator::{min,ewma}_rtt_usec()` docs, which state that both functions are supposed to return `u32::MAX` if there is no estimate. Closes #2049

fix: fix typos

2025-01-30T08:39:30Z

congestion: Use getters for all parameters

2025-01-16T14:16:01Z

Allows us to remove the pub. Signed-off-by: David Goulet

congestion: Add standard clippy checks to tests

2025-01-16T14:16:01Z

Signed-off-by: David Goulet

congestion: Make a test_utils.rs

2025-01-16T14:16:01Z

Instead of having the congestion.rs test module public, make a test_utils.rs file that contains code for other unit tests within the congestion module. Signed-off-by: David Goulet

congestion: Remove duplicate RttParameters struct

2025-01-16T14:16:01Z

Turns out that RoundTripEstimatorParams is the same exact thing so one less data structure. Signed-off-by: David Goulet

proto: Add generic objects for congestion control

2025-01-16T14:16:01Z

This commit adds the congestion window object, a round trip estimator (RTT) and a state enum. These 3 entities are used by congestion control in a generic way that is they are passed and used by any algorithm. At this commit, they are not used hence the allow deadcode attribute for now in order to minimize the build warnings. We also introduce the params.rs file containing the parameters, taken from consensus, used to configure these objects. They will be exposed to the tor-cirmgr crate to build the CircParameters. More will come. This also introduces the congestion/ directory that will contain more code in future commits. Related #534 Signed-off-by: David Goulet