Implement Brioche.gitRef() for locked git refs (#126)

crates/brioche-core/Cargo.toml

@@ -65,6 +65,7 @@ urlencoding = "2.1.3"
 walkdir = "2.5.0"
 petgraph = "0.6.5"
 wax = { version = "0.6.0", default-features = false }
+gix = { version = "0.66.0", features = ["blocking-network-client", "blocking-http-transport-reqwest"] }
 
 [dev-dependencies]
 assert_matches = "1.5.0"

crates/brioche-core/src/download.rs

@@ -80,3 +80,126 @@ pub async fn download(
 
     Ok(blob_hash)
 }
+
+pub async fn fetch_git_commit_for_ref(repository: &url::Url, ref_: &str) -> anyhow::Result<String> {
+    let (tx, rx) = tokio::sync::oneshot::channel::<anyhow::Result<_>>();
+
+    // gix uses a blocking client, so spawn a separate thread to fetch
+    std::thread::spawn({
+        let repository: gix::Url = repository
+            .as_str()
+            .try_into()
+            .with_context(|| format!("failed to parse git repository URL: {repository}"))?;
+        move || {
+            // Connect to the repository by URL
+            let transport = gix::protocol::transport::connect(repository, Default::default());
+            let mut transport = match transport {
+                Ok(transport) => transport,
+                Err(error) => {
+                    let _ = tx.send(Err(error.into()));
+                    return;
+                }
+            };
+
+            // Perform a handshake to get the remote's capabilities.
+            // Authentication is disabled
+            let empty_auth = |_| Ok(None);
+            let outcome = gix::protocol::fetch::handshake(
+                &mut transport,
+                empty_auth,
+                vec![],
+                &mut gix::progress::Discard,
+            );
+            let outcome = match outcome {
+                Ok(outcome) => outcome,
+                Err(error) => {
+                    let _ = gix::protocol::indicate_end_of_interaction(&mut transport, false);
+                    let _ = tx.send(Err(error.into()));
+                    return;
+                }
+            };
+
+            let refs = match outcome.refs {
+                Some(refs) => {
+                    // The handshake will sometimes return the refs directly,
+                    // depending on protocol version. If that happens, we're
+                    // done
+                    refs
+                }
+                None => {
+                    // Fetch the refs
+                    let refs = gix::protocol::ls_refs(
+                        &mut transport,
+                        &outcome.capabilities,
+                        |_, _, _| Ok(gix::protocol::ls_refs::Action::Continue),
+                        &mut gix::progress::Discard,
+                        false,
+                    );
+                    match refs {
+                        Ok(refs) => refs,
+                        Err(error) => {
+                            let _ =
+                                gix::protocol::indicate_end_of_interaction(&mut transport, false);
+                            let _ = tx.send(Err(error.into()));
+                            return;
+                        }
+                    }
+                }
+            };
+
+            // End the interaction with the remote
+            let _ = gix::protocol::indicate_end_of_interaction(&mut transport, false);
+
+            let _ = tx.send(Ok(refs));
+        }
+    });
+
+    let remote_refs = rx.await?;
+    let remote_refs = match remote_refs {
+        Ok(remote_refs) => remote_refs,
+        Err(error) => {
+            anyhow::bail!("{error}");
+        }
+    };
+
+    // Find the ref that matches the requested ref name
+    let object_id = remote_refs
+        .iter()
+        .find_map(|remote_ref| {
+            let (name, object) = match remote_ref {
+                gix::protocol::handshake::Ref::Peeled {
+                    full_ref_name,
+                    object,
+                    ..
+                } => (full_ref_name, object),
+                gix::protocol::handshake::Ref::Direct {
+                    full_ref_name,
+                    object,
+                } => (full_ref_name, object),
+                gix::protocol::handshake::Ref::Symbolic {
+                    full_ref_name,
+                    object,
+                    ..
+                } => (full_ref_name, object),
+                gix::protocol::handshake::Ref::Unborn { .. } => {
+                    return None;
+                }
+            };
+
+            if let Some(tag_name) = name.strip_prefix(b"refs/tags/") {
+                if tag_name == ref_.as_bytes() {
+                    return Some(object);
+                }
+            } else if let Some(head_name) = name.strip_prefix(b"refs/heads/") {
+                if head_name == ref_.as_bytes() {
+                    return Some(object);
+                }
+            }
+
+            None
+        })
+        .with_context(|| format!("git ref '{ref_}' not found in repo {repository}"))?;
+
+    let commit = object_id.to_string();
+    Ok(commit)
+}

crates/brioche-core/src/project.rs

@@ -4,13 +4,13 @@ use std::{
     sync::Arc,
 };
 
-use analyze::{StaticOutput, StaticOutputKind, StaticQuery};
+use analyze::{GitRefOptions, StaticOutput, StaticOutputKind, StaticQuery};
 use anyhow::Context as _;
 use futures::{StreamExt as _, TryStreamExt as _};
 use relative_path::{PathExt as _, RelativePath, RelativePathBuf};
 use tokio::io::{AsyncReadExt as _, AsyncWriteExt as _};
 
-use crate::recipe::{Artifact, RecipeHash};
+use crate::recipe::Artifact;
 
 use super::{vfs::FileId, Brioche};
 
@@ -314,7 +314,7 @@ impl Projects {
         &self,
         specifier: &super::script::specifier::BriocheModuleSpecifier,
         static_: &StaticQuery,
-    ) -> anyhow::Result<Option<RecipeHash>> {
+    ) -> anyhow::Result<Option<StaticOutput>> {
         let projects = self
             .inner
             .read()
@@ -450,7 +450,7 @@ impl ProjectsInner {
         &self,
         specifier: &super::script::specifier::BriocheModuleSpecifier,
         static_: &StaticQuery,
-    ) -> anyhow::Result<Option<RecipeHash>> {
+    ) -> anyhow::Result<Option<StaticOutput>> {
         let path = match specifier {
             super::script::specifier::BriocheModuleSpecifier::File { path } => path,
             _ => {
@@ -485,8 +485,7 @@ impl ProjectsInner {
         let Some(Some(output)) = statics.get(static_) else {
             return Ok(None);
         };
-        let recipe_hash = static_.output_recipe_hash(output)?;
-        Ok(Some(recipe_hash))
+        Ok(Some(output.clone()))
     }
 }
 
@@ -994,7 +993,9 @@ async fn fetch_project_from_registry(
         };
 
         let recipe_hash = static_.output_recipe_hash(output)?;
-        statics_recipes.insert(recipe_hash);
+        if let Some(recipe_hash) = recipe_hash {
+            statics_recipes.insert(recipe_hash);
+        }
     }
 
     crate::registry::fetch_recipes_deep(brioche, statics_recipes).await?;
@@ -1012,6 +1013,7 @@ async fn fetch_project_from_registry(
 
             match static_ {
                 StaticQuery::Include(include) => {
+                    let recipe_hash = recipe_hash.context("no recipe hash for include static")?;
                     let recipe = crate::recipe::get_recipe(brioche, recipe_hash).await?;
                     let artifact: crate::recipe::Artifact = recipe.try_into().map_err(|_| {
                         anyhow::anyhow!("included static recipe is not an artifact")
@@ -1031,6 +1033,7 @@ async fn fetch_project_from_registry(
                     .await?;
                 }
                 StaticQuery::Glob { .. } => {
+                    let recipe_hash = recipe_hash.context("no recipe hash for glob static")?;
                     let recipe = crate::recipe::get_recipe(brioche, recipe_hash).await?;
                     let artifact: crate::recipe::Artifact = recipe.try_into().map_err(|_| {
                         anyhow::anyhow!("included static recipe is not an artifact")
@@ -1048,7 +1051,7 @@ async fn fetch_project_from_registry(
                     )
                     .await?;
                 }
-                StaticQuery::Download { .. } => {
+                StaticQuery::Download { .. } | StaticQuery::GitRef { .. } => {
                     // No need to do anything while fetching the project
                 }
             }
@@ -1091,27 +1094,37 @@ async fn fetch_project_from_registry(
         .iter()
         .map(|(name, hash)| (name.clone(), *hash))
         .collect();
-    let downloads = project
-        .statics
-        .values()
-        .flatten()
-        .filter_map(|(static_, output)| {
-            let url = match static_ {
-                StaticQuery::Download { url, .. } => url,
-                _ => return None,
-            };
 
-            let hash = match output {
-                Some(StaticOutput::Kind(StaticOutputKind::Download { hash })) => hash,
-                _ => return None,
-            };
+    let mut downloads = BTreeMap::new();
+    let mut git_refs = BTreeMap::new();
+    for (static_, output) in project.statics.values().flatten() {
+        match static_ {
+            StaticQuery::Include(_) | StaticQuery::Glob { .. } => {
+                continue;
+            }
+            StaticQuery::Download { url } => {
+                let Some(StaticOutput::Kind(StaticOutputKind::Download { hash })) = output else {
+                    continue;
+                };
+
+                downloads.insert(url.clone(), hash.clone());
+            }
+            StaticQuery::GitRef(GitRefOptions { repository, ref_ }) => {
+                let Some(StaticOutput::Kind(StaticOutputKind::GitRef { commit })) = output else {
+                    continue;
+                };
+
+                let repo_refs: &mut BTreeMap<_, _> =
+                    git_refs.entry(repository.clone()).or_default();
+                repo_refs.insert(ref_.clone(), commit.clone());
+            }
+        }
+    }
 
-            Some((url.clone(), hash.clone()))
-        })
-        .collect();
     let lockfile = Lockfile {
         dependencies,
         downloads,
+        git_refs,
     };
     let lockfile_path = temp_project_path.join("brioche.lock");
     let lockfile_contents =
@@ -1439,6 +1452,37 @@ async fn resolve_static(
                 hash: download_hash,
             }))
         }
+        StaticQuery::GitRef(GitRefOptions { repository, ref_ }) => {
+            let current_commit = lockfile.and_then(|lockfile| {
+                lockfile
+                    .git_refs
+                    .get(repository)
+                    .and_then(|repo_refs| repo_refs.get(ref_))
+            });
+
+            let commit = if let Some(commit) = current_commit {
+                commit.clone()
+            } else if lockfile_required {
+                // Error out if the git ref isn't in the lockfile but where
+                // updating the lockfile is disabled
+                anyhow::bail!(
+                    "commit for git repo '{repository}' ref '{ref_}' not found in lockfile"
+                );
+            } else {
+                // Fetch the current commit hash of the git ref from the repo
+                crate::download::fetch_git_commit_for_ref(repository, ref_)
+                    .await
+                    .with_context(|| {
+                        format!("failed to fetch ref '{ref_}' from git repo '{repository}'")
+                    })?
+            };
+
+            // Update the new lockfile with the commit
+            let repo_refs = new_lockfile.git_refs.entry(repository.clone()).or_default();
+            repo_refs.insert(ref_.clone(), commit.clone());
+
+            Ok(StaticOutput::Kind(StaticOutputKind::GitRef { commit }))
+        }
     }
 }
 
@@ -1671,4 +1715,7 @@ pub struct Lockfile {
 
     #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
     pub downloads: BTreeMap<url::Url, crate::Hash>,
+
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub git_refs: BTreeMap<url::Url, BTreeMap<String, String>>,
 }