perf(lockfile): byte-cursor subset parser for pnpm-lock.yaml

crates/aube-lockfile/Cargo.toml

@@ -28,7 +28,20 @@ blake3 = { workspace = true }
 thiserror = { workspace = true }
 tracing = { workspace = true }
 smallvec = { workspace = true }
+memchr = "2"
+
+[features]
+# Exposes the `__bench_parse_*` shims used by the `pnpm_lock_parse`
+# bench. Off by default so the bench helpers stay out of the crate's
+# public API surface.
+bench = []
 
 [dev-dependencies]
 proptest = "1"
 tempfile = "3"
+criterion = { version = "0.5", default-features = false }
+
+[[bench]]
+name = "pnpm_lock_parse"
+harness = false
+required-features = ["bench"]

crates/aube-lockfile/benches/pnpm_lock_parse.rs

@@ -0,0 +1,40 @@
+//! Old-vs-new parse benchmark for `pnpm-lock.yaml`.
+//!
+//! Compares the general `yaml_serde` parse path against the byte-cursor
+//! subset parser on a large generated lockfile. Set
+//! `AUBE_BENCH_LOCKFILE=/path/to/pnpm-lock.yaml` to point at a real
+//! lockfile instead of the bundled small fixture.
+
+use aube_lockfile::pnpm;
+use criterion::{Criterion, criterion_group, criterion_main};
+use std::hint::black_box;
+
+fn load() -> String {
+    if let Ok(p) = std::env::var("AUBE_BENCH_LOCKFILE") {
+        return std::fs::read_to_string(p).expect("read AUBE_BENCH_LOCKFILE");
+    }
+    include_str!("../tests/fixtures/pnpm-native.yaml").to_string()
+}
+
+fn bench(c: &mut Criterion) {
+    let content = load();
+    eprintln!("benchmarking pnpm-lock.yaml: {} bytes", content.len());
+
+    // Sanity: both paths must agree on the structure they parse.
+    let s = pnpm::__bench_parse_subset(&content);
+    let y = pnpm::__bench_parse_serde(&content);
+    assert!(s.is_some(), "subset parser declined the bench input");
+    assert_eq!(s, y, "subset and serde parsers disagree on counts");
+
+    let mut g = c.benchmark_group("pnpm-lock-parse");
+    g.bench_function("serde", |b| {
+        b.iter(|| black_box(pnpm::__bench_parse_serde(black_box(&content))))
+    });
+    g.bench_function("subset", |b| {
+        b.iter(|| black_box(pnpm::__bench_parse_subset(black_box(&content))))
+    });
+    g.finish();
+}
+
+criterion_group!(benches, bench);
+criterion_main!(benches);

crates/aube-lockfile/src/pnpm/mod.rs

@@ -3,6 +3,7 @@ mod dep_path;
 mod format;
 mod raw;
 mod read;
+mod subset;
 mod write;
 
 #[cfg(test)]
@@ -12,6 +13,26 @@ pub use checksum::{package_extensions_checksum, pnpmfile_checksum};
 pub use read::parse;
 pub use write::write;
 
+/// Benchmark-only shims comparing the byte-cursor subset parser against
+/// the general `yaml_serde` parser on raw `pnpm-lock.yaml` content.
+/// Returns `(packages, snapshots, importers)` counts so the bench's
+/// black-box can't be optimized away. Gated behind the `bench` feature
+/// so they are not part of the crate's default public surface.
+#[cfg(feature = "bench")]
+#[doc(hidden)]
+pub fn __bench_parse_subset(content: &str) -> Option<(usize, usize, usize)> {
+    subset::try_parse(content).map(|r| raw::__bench_counts(&r))
+}
+
+/// Benchmark-only: parse via the original serde path.
+#[cfg(feature = "bench")]
+#[doc(hidden)]
+pub fn __bench_parse_serde(content: &str) -> Option<(usize, usize, usize)> {
+    raw::parse_raw_lockfile_serde(content)
+        .ok()
+        .map(|r| raw::__bench_counts(&r))
+}
+
 pub(super) fn tarball_url_is_hosted_git(url: &str) -> bool {
     let Some((host, path)) = http_url_host_and_path(url) else {
         return false;