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perf(pm): dedup version-manifest disk writes via OnceMap #2882

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perf(pm): dedup version-manifest disk writes via OnceMap #2882

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28 changes: 26 additions & 2 deletions crates/pm/src/util/manifest_store.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,16 +16,27 @@ use async_trait::async_trait;
use serde::Serialize;
use utoo_ruborist::model::manifest::CoreVersionManifest;
use utoo_ruborist::service::{ManifestStore, VersionsInfo};
use utoo_ruborist::util::OnceMap;

use crate::util::json::read_json_file;

pub struct DiskManifestStore {
cache_dir: PathBuf,
/// Dedup `(name, resolved_version)` disk writes. The upstream
/// `inflight_version<(name, original_spec)>` gate keys on the original
/// spec, so two specs (`^4.17.0`, `~4.17.20`) resolving to the same
/// `4.17.21` each call `store_version_manifest` and would otherwise
/// spawn duplicate `write_json` tasks racing on truncate of the same
/// path. `OnceMap::register` is a sync, atomic "first wins" check.
inflight_version_writes: Arc<OnceMap<(String, String), ()>>,
}

impl DiskManifestStore {
pub fn new(cache_dir: PathBuf) -> Self {
Self { cache_dir }
Self {
cache_dir,
inflight_version_writes: Arc::new(OnceMap::new()),
}
}

fn versions_path(&self, name: &str) -> PathBuf {
Expand Down Expand Up @@ -67,8 +78,21 @@ impl ManifestStore for DiskManifestStore {
version: &str,
manifest: Arc<CoreVersionManifest>,
) {
let key = (name.to_string(), version.to_string());
let Some(notify) = self.inflight_version_writes.register(key.clone()) else {
// Another caller already enqueued this write — skip the
// duplicate serialize + spawn + truncate-race.
return;
};
let path = self.manifest_path(name, version);
tokio::spawn(async move { write_json(&path, &*manifest).await });
// Move an `Arc` clone of the OnceMap into the task so we can
// transition Waiting → Done after the write completes; this also
// notifies any future `wait_if_pending` callers.
let inflight = Arc::clone(&self.inflight_version_writes);
tokio::spawn(async move {
write_json(&path, &*manifest).await;
inflight.complete(key, Some(()), notify);
Comment on lines +93 to +94

@gemini-code-assist gemini-code-assist Bot May 1, 2026

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medium

The write is currently marked as complete with Some(()) regardless of whether write_json succeeds or fails. Since OnceMap::register returns None for any key already in the Done state, a single failed write (e.g., due to a transient I/O error or disk full condition) will prevent any subsequent attempts to persist that specific version manifest for the lifetime of the process. This results in persistent cache misses for that version.

Consider updating write_json to return a success boolean and using inflight.complete(key, success.then_some(()), notify) here. This ensures that if a write fails, the key is removed from the map (via None), allowing future calls to retry the operation.

});
}
}

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