fix: lock git dependencies folder when resolving workspace

tooling/nargo_toml/Cargo.toml

@@ -23,6 +23,8 @@ toml.workspace = true
 url.workspace = true
 noirc_driver.workspace = true
 semver = "1.0.20"
+fs2 = "0.4.3"
+tracing.workspace = true
 
 [dev-dependencies]
 tempfile.workspace = true

tooling/nargo_toml/src/flock.rs

@@ -0,0 +1,33 @@
+use fs2::FileExt;
+use std::{
+    fs::{File, OpenOptions},
+    path::Path,
+};
+
+// TODO: move this to some utils crate.
+
+pub(crate) struct FileLock {
+    file: File,
+}
+
+impl FileLock {
+    pub(crate) fn new(file_path: &Path, lock_name: &str) -> std::io::Result<Self> {
+        std::fs::create_dir_all(file_path.parent().expect("can't create lock on filesystem root"))?;
+        let file = OpenOptions::new().create(true).truncate(false).write(true).open(file_path)?;
+        if file.try_lock_exclusive().is_err() {
+            eprintln!("Waiting for lock on {lock_name}...");
+        }
+
+        file.lock_exclusive()?;
+
+        Ok(Self { file })
+    }
+}
+
+impl Drop for FileLock {
+    fn drop(&mut self) {
+        if let Err(e) = self.file.unlock() {
+            tracing::warn!("failed to release lock: {e:?}");
+        }
+    }
+}

tooling/nargo_toml/src/git.rs

@@ -1,5 +1,7 @@
 use std::path::PathBuf;
 
+use crate::flock::FileLock;
+
 /// Creates a unique folder name for a GitHub repo
 /// by using its URL and tag
 fn resolve_folder_name(base: &url::Url, tag: &str) -> String {
@@ -23,6 +25,10 @@ fn git_dep_location(base: &url::Url, tag: &str) -> PathBuf {
     nargo_crates().join(folder_name)
 }
 
+pub(crate) fn lock_git_deps() -> std::io::Result<FileLock> {
+    FileLock::new(&nargo_crates().join(".package-cache"), "git dependencies cache")
+}
+
 /// XXX: I'd prefer to use a GitHub library however, there
 /// does not seem to be an easy way to download a repo at a specific
 /// tag

tooling/nargo_toml/src/lib.rs

@@ -19,11 +19,12 @@ use noirc_frontend::graph::CrateName;
 use serde::Deserialize;
 
 mod errors;
+mod flock;
 mod git;
 mod semver;
 
 pub use errors::ManifestError;
-use git::clone_git_repo;
+use git::{clone_git_repo, lock_git_deps};
 
 /// Searches for a `Nargo.toml` file in the current directory and all parent directories.
 /// For example, if the current directory is `/workspace/package/src`, then this function
@@ -382,6 +383,7 @@ fn toml_to_workspace(
     package_selection: PackageSelection,
 ) -> Result<Workspace, ManifestError> {
     let mut resolved = Vec::new();
+    let _lock = lock_git_deps().expect("Failed to lock git dependencies cache");
     let workspace = match nargo_toml.config {
         Config::Package { package_config } => {
             let member = package_config.resolve_to_package(&nargo_toml.root_dir, &mut resolved)?;
@@ -519,6 +521,7 @@ pub fn resolve_workspace_from_toml(
 ) -> Result<Workspace, ManifestError> {
     let nargo_toml = read_toml(toml_path)?;
     let workspace = toml_to_workspace(nargo_toml, package_selection)?;
+
     if let Some(current_compiler_version) = current_compiler_version {
         semver::semver_check_workspace(&workspace, current_compiler_version)?;
     }