Trait FracPair 

pub trait FracPair {
    // Required method
    fn frac_pair(&self, other: &Self) -> BTreeMap<Phase, f64>;
}

Per-phase “share of total” reducer. Specialized for the dominant counter shape (BTreeMap<Phase, u64>) because u64: Into<f64> is intentionally absent (cast is lossy) — a generic PhaseMapExt method with an Into<f64> bound would reject every counter-delta map test authors actually reach for.

For every phase present in BOTH self AND other, computes self_value as f64 / (self_value + other_value) as f64. When both values are zero (sum is zero), the phase is dropped from the result — there is no signal to share, and synthesizing 0.0 would let downstream at_most / ratio_within gates silently pass on a zero-event phase pair. Returning no entry surfaces the absence so the consumer can treat it as Inconclusive (the same shape as a phase only present in one input). Phases present in only one input also drop from the result, mirroring PhaseMapExt::zip_per_phase’s intersection-only semantics; both drop conditions surface identically as “no entry for this phase.”

Targets the “cross-LLC dispatch fraction” idiom (nr_cross / (nr_cross + nr_same)) and similar share-of-total patterns. The general fold via PhaseMapExt::zip_per_phase requires the caller to spell the safe-divide branch inline at every call site; this trait owns the branch so test code expresses the metric in one chain.

Required Methods

fn frac_pair(&self, other: &Self) -> BTreeMap<Phase, f64>

See trait-level doc for the zero-total drop and intersection-only semantics.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl FracPair for BTreeMap<Phase, u64>

fn frac_pair(&self, other: &Self) -> BTreeMap<Phase, f64>

Implementors