Struct BudgetController 

pub struct BudgetController { /* private fields */ }

Adaptive budget controller combining PID regulation with e-process gating.

Architecture

frame_time ─┬─► PID Controller ─► control signal u_t
            │                              │
            └─► E-Process ──────► gate ────┤
                                           ▼
                                   Decision Logic
                                   ┌───────────────┐
                                   │ u_t > thresh   │──► DEGRADE (if e-process permits)
                                   │ u_t < -thresh  │──► UPGRADE (if e-process permits)
                                   │ otherwise      │──► HOLD
                                   └───────────────┘

The PID controller provides smooth, reactive adaptation. The e-process gates decisions to ensure statistical validity — we only degrade when there is strong evidence of sustained overload, not just transient spikes.

Usage

use ftui_render::budget::{BudgetController, BudgetControllerConfig, DegradationLevel};
use std::time::Duration;

let mut controller = BudgetController::new(BudgetControllerConfig::default());

// After each frame, feed the observed frame time:
let decision = controller.update(Duration::from_millis(20)); // slow frame
// decision tells you what to do: Hold, Degrade, or Upgrade

Implementations

impl BudgetController

pub fn new(config: BudgetControllerConfig) -> Self

Create a new budget controller with the given configuration.

pub fn update(&mut self, frame_time: Duration) -> BudgetDecision

Feed a frame time observation and get a decision.

Call this once per frame with the measured frame duration.

pub fn level(&self) -> DegradationLevel

Get the current degradation level.

pub fn e_value(&self) -> f64

Get the current e-process value (for diagnostics/logging).

pub fn eprocess_sigma_ms(&self) -> f64

Get the current e-process sigma estimate (ms).

pub fn pid_integral(&self) -> f64

Get the current PID integral term (for diagnostics/logging).

pub fn frames_observed(&self) -> u32

Get the number of frames observed by the e-process.

pub fn telemetry(&self) -> BudgetTelemetry

Capture a telemetry snapshot of the controller state.

This is allocation-free and suitable for calling every frame. Forward the result to a debug overlay or structured logger.

pub fn reset(&mut self)

Reset the controller to initial state.

pub fn config(&self) -> &BudgetControllerConfig

Get a reference to the controller configuration.

Trait Implementations

impl Clone for BudgetController

fn clone(&self) -> BudgetController

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BudgetController

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

Formats the value using the given formatter.