Struct Budget 

pub struct Budget {
    pub loops: u32,
    pub instructions: u32,
}

What one run may spend: how many iterations any single loop may take, and how many instructions the whole run may execute.

Per program rather than one constant, because the three programs of a bundle cost wildly different amounts. per_frame_init runs once at load; per_frame runs once a frame; per_vertex runs once per vertex, thousands of times a frame. A single bound tight enough for the third would break the first — the corpus’s commonest per_frame_init idiom is loop(10000, megabuf(index) = .1; index = index + 1), seeding a scratch array, and 84 presets in the largest pack do exactly that.

Both numbers are bounds, not budgets: nothing is reserved and an honest program never approaches either. What they buy is that untrusted program text cannot hang a frame, which is ADR-0113’s stated residual risk on the shader side and is closed on this side.

Fields

loops: u32

The most iterations any one loop() or while() may run.

instructions: u32

The most instructions the whole run may execute — the backstop under the loop bound, so a program whose bare jumps form a cycle still terminates.

Implementations

impl Budget

pub const INIT: Self

per_frame_init: runs once, at preset load, off the hot path. The loop bound is MilkDrop’s own (1 << 20), and the instruction bound is generous enough that seeding a whole megabuf fits.

pub const FRAME: Self

per_frame: once a frame. A million instructions is a few milliseconds on the CPUs this ships to — far past any real preset, and far under a stall.

pub const VERTEX: Self

per_vertex: once per vertex, so its bound is multiplied by the mesh. At the rich tier’s 5 963 vertices this ceiling is still 49 M instructions a frame in the worst case, which is why it is three orders under the others — real per-vertex programs are a few hundred instructions, and the measured tier ladder (TierConfig::mesh_grid) is priced against that.

Trait Implementations

impl Clone for Budget

fn clone(&self) -> Budget

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Budget

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

Formats the value using the given formatter.

impl PartialEq for Budget

fn eq(&self, other: &Budget) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Budget

impl Eq for Budget

impl StructuralPartialEq for Budget