From eda9cb31cdfa07d4a61875043bdaf6151edb5d9c Mon Sep 17 00:00:00 2001
From: Charlie Marsh <charlie.r.marsh@gmail.com>
Date: Sat, 11 May 2024 13:15:58 -0400
Subject: [PATCH] Apply advisory locks when building source distributions

---
 crates/uv-cache/src/lib.rs               |  6 ++++++
 crates/uv-distribution/src/source/mod.rs | 16 ++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/crates/uv-cache/src/lib.rs b/crates/uv-cache/src/lib.rs
index 3805d6cf8d3..1e840f23fc3 100644
--- a/crates/uv-cache/src/lib.rs
+++ b/crates/uv-cache/src/lib.rs
@@ -94,6 +94,12 @@ impl CacheShard {
     pub fn shard(&self, dir: impl AsRef<Path>) -> Self {
         Self(self.0.join(dir.as_ref()))
     }
+
+    /// Acquire a lock on the shard.
+    pub fn lock(&self) -> io::Result<uv_fs::LockedFile> {
+        fs_err::create_dir_all(&self.0)?;
+        uv_fs::LockedFile::acquire(self.0.join(".lock"), self.0.display())
+    }
 }
 
 impl AsRef<Path> for CacheShard {
diff --git a/crates/uv-distribution/src/source/mod.rs b/crates/uv-distribution/src/source/mod.rs
index 9d12385b817..70c6ab82dc9 100644
--- a/crates/uv-distribution/src/source/mod.rs
+++ b/crates/uv-distribution/src/source/mod.rs
@@ -396,6 +396,8 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         hashes: HashPolicy<'_>,
         client: &ManagedClient<'_>,
     ) -> Result<BuiltWheelMetadata, Error> {
+        let _lock = cache_shard.lock().map_err(Error::CacheWrite)?;
+
         // Fetch the revision for the source distribution.
         let revision = self
             .url_revision(source, filename, url, cache_shard, hashes, client)
@@ -465,6 +467,8 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         hashes: HashPolicy<'_>,
         client: &ManagedClient<'_>,
     ) -> Result<ArchiveMetadata, Error> {
+        let _lock = cache_shard.lock().map_err(Error::CacheWrite)?;
+
         // Fetch the revision for the source distribution.
         let revision = self
             .url_revision(source, filename, url, cache_shard, hashes, client)
@@ -625,6 +629,8 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         tags: &Tags,
         hashes: HashPolicy<'_>,
     ) -> Result<BuiltWheelMetadata, Error> {
+        let _lock = cache_shard.lock().map_err(Error::CacheWrite)?;
+
         // Fetch the revision for the source distribution.
         let revision = self
             .archive_revision(source, resource, cache_shard, hashes)
@@ -691,6 +697,8 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         cache_shard: &CacheShard,
         hashes: HashPolicy<'_>,
     ) -> Result<ArchiveMetadata, Error> {
+        let _lock = cache_shard.lock().map_err(Error::CacheWrite)?;
+
         // Fetch the revision for the source distribution.
         let revision = self
             .archive_revision(source, resource, cache_shard, hashes)
@@ -838,6 +846,8 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             WheelCache::Path(resource.url).root(),
         );
 
+        let _lock = cache_shard.lock().map_err(Error::CacheWrite)?;
+
         // Fetch the revision for the source distribution.
         let revision = self
             .source_tree_revision(source, resource, &cache_shard)
@@ -902,6 +912,8 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             WheelCache::Path(resource.url).root(),
         );
 
+        let _lock = cache_shard.lock().map_err(Error::CacheWrite)?;
+
         // Fetch the revision for the source distribution.
         let revision = self
             .source_tree_revision(source, resource, &cache_shard)
@@ -1039,6 +1051,8 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             WheelCache::Git(&url, &git_sha.to_short_string()).root(),
         );
 
+        let _lock = cache_shard.lock().map_err(Error::CacheWrite)?;
+
         // If the cache contains a compatible wheel, return it.
         if let Some(built_wheel) = BuiltWheelMetadata::find_in_cache(tags, &cache_shard) {
             return Ok(built_wheel);
@@ -1111,6 +1125,8 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
             WheelCache::Git(&url, &git_sha.to_short_string()).root(),
         );
 
+        let _lock = cache_shard.lock().map_err(Error::CacheWrite)?;
+
         // If the cache contains compatible metadata, return it.
         let metadata_entry = cache_shard.entry(METADATA);
         if self