Struct FlowControl 

pub struct FlowControl { /* private fields */ }

Window-based flow control state for managing reliable data transmission.

This struct encapsulates the state needed for sliding window flow control, including the current window size and tracking of in-transit reliable data.

Implementations

impl FlowControl

pub fn new(config: &Config) -> Self

Creates a new flow control instance with configuration defaults.

Arguments

• config - Configuration containing initial window size and limits

Example

use bitfold_peer::flow_control::FlowControl;
use bitfold_core::config::Config;

let config = Config::default();
let flow_control = FlowControl::new(&config);

pub fn window_size(&self) -> u32

Returns the current window size (in packets).

The window size represents the maximum number of packets that can be in flight (unacknowledged) at any given time.

pub fn reliable_data_in_transit(&self) -> u32

Returns the amount of reliable data currently in transit (in bytes).

This tracks the total bytes of reliable data that have been sent but not yet acknowledged by the receiver.

pub fn set_window_size(&mut self, config: &Config, window_size: u32)

Sets the window size (for negotiation during handshake).

The provided window size will be clamped to the configured min/max bounds.

Arguments

• config - Configuration containing min and max window size limits
• window_size - Desired window size (will be clamped to min/max)

pub fn record_reliable_data_sent(&mut self, data_size: u32)

Records reliable data being sent (adds to in-transit counter).

Call this method whenever reliable data is transmitted to track how much data is waiting for acknowledgment.

Arguments

• data_size - Size of the data being sent, in bytes

pub fn record_reliable_data_acked(&mut self, data_size: u32)

Records reliable data being acknowledged (removes from in-transit counter).

Call this method when an acknowledgment is received to reduce the amount of tracked in-transit data.

Arguments

• data_size - Size of the data being acknowledged, in bytes

pub fn can_send_reliable(&self, config: &Config, packets_in_flight: u16) -> bool

Checks if we can send more data based on window-based flow control.

Returns true if we have room in the window, false if the window is full. When window flow control is disabled, this falls back to checking a simple packet count limit.

Arguments

• config - Configuration containing window control settings
• packets_in_flight - Current number of unacknowledged packets (used when window flow control is disabled)

Returns

true if more reliable data can be sent, false if the window is full

pub fn adjust_window_size( &mut self, config: &Config, loss_rate: f32, rtt_ms: u32, )

Dynamically adjusts the window size based on network conditions.

This should be called periodically to adapt the window size to changing network conditions. The window grows during good conditions and shrinks during poor conditions.

Adjustment Logic

• Increase: When loss rate < 1% and RTT < 200ms, grow window by ~3% (1/32)
• Decrease: When loss rate > 5% or RTT > 500ms, shrink window by ~6% (1/16)
• No change: Otherwise maintain current window size

The window size is always clamped to the configured min/max bounds.

Arguments

• config - Configuration containing window control settings and limits
• loss_rate - Current packet loss rate (0.0 to 1.0)
• rtt_ms - Current round-trip time in milliseconds

Trait Implementations

impl Clone for FlowControl

fn clone(&self) -> FlowControl

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FlowControl

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FlowControl

fn default() -> Self

Returns the “default value” for a type.