Expand description
Congestion control subsystem.
This object is attached to a circuit hop (CircHop) and controls the logic for the congestion control support of the Tor Network. It also manages the circuit level SENDME logic which is part of congestion control.
§Implementation
The basics of this subsystem is that it is notified when a DATA cell is received or sent. This
in turn updates the congestion control state so that the very important
can_send function be accurate to decide if a DATA cell can be
sent or not.
Any part of the arti code that wants to send a DATA cell on the wire needs to call
can_send before else we’ll risk leaving the circuit in a
protocol violation state.
Furthermore, as we receive and emit SENDMEs, it also has entry point for those two events in order to update the state.
Modules§
- fixed 🔒
- Implementation of the Fixed Window congestion control algorithm.
- params
- Define the congestion control parameters needed for the algorithms.
- rtt 🔒
- Round Trip Time measurement (§ 2.1)
- sendme 🔒
- Management for flow control windows.
- test_
utils 🔒testing - Test helpers.
- vegas 🔒
- Implementation of the Tor Vegas congestion control algorithm.
Structs§
- Congestion
Control 🔒 - Congestion control state of a hop on a circuit.
- Congestion
Signals 🔒 - These are congestion signals used by a congestion control algorithm to make decisions. These signals are various states of our internals. This is not an exhaustive list.
- Congestion
Window 🔒 - A congestion window. This is generic for all algorithms but their parameters’ value will differ depending on the selected algorithm.
Enums§
- State 🔒
- Congestion control state.
Traits§
- Congestion
Control 🔒Algorithm - This trait defines what a congestion control algorithm must implement in order to interface with the circuit reactor.