subms (Rust)

The Rust side of the subms perf harness. Zero-dependency std-only crate. Records timed samples per stage, computes percentiles, supports coordinated-omission correction, runs scale sweeps, and emits a JSON contract byte-equivalent to the Java side.

See the repo-root README for the cross-language overview, JSON-contract spec, and ecosystem links.

Install

[dependencies]
subms = "0.3"

Quickstart

use subms::{
    SubMsPerfHarness, summarize, print_summary,
    assert_p99_under, SubMsBenchAssertion,
};

let mut h = SubMsPerfHarness::new("my-workload", "rust");
h.input("entries", "50000");

let put = h.stage("put", 50_000);
for _ in 0..50_000 {
    put.time(|| { /* hot-path work under test */ });
}

let summary = summarize(&h);
print_summary(&summary, &mut std::io::stdout())?;

assert_p99_under(
    &summary,
    &[SubMsBenchAssertion { stage: "put", p99_ns_max: 1_000_000 }],
)?;

Feature flags

flag	what it enables
(default)	The harness, summary, sweep, diff, timer, paced stage, JSON emission. Pure std-lib.

No optional features today. The crate stays small and dependency-free on purpose.

Public API surface

type / fn	does
`SubMsPerfHarness`	records timed samples per named stage
`SubMsStage` / `SubMsPacedStage`	per-stage recorder (paced = coordinated-omission corrected)
`summarize(&h)` / `summarize_lean(&h)`	sorted percentiles + downsampled timeline
`print_summary(&s, &mut writer)`	fixed-width percentile table
`summary_to_json(&s, &mut writer)`	the stable JSON shape
`run_sweep(&recipe, &[params...], varied_key)`	multi-run scale curve / feature toggle
`diff_summary(&base, &cand)`	typed per-stage regression delta
`assert_p99_under(&target, &[...])`	the cookbook quality gate
`SubMsTimer`	autostart stopwatch with named checkpoints
`SubMsRecipe` trait	implement for cookbook-style standardised benches

Full reference at docs.rs/subms.

License