Colocated workspaces using git worktrees

CHANGELOG.md

@@ -27,6 +27,10 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 * New `at_operation(op, expr)` revset can be used in order to query revisions
   based on historical state.
 
+* `jj workspace add` now accepts a `--colocate` flag, which makes the new
+  workspace into a valid git worktree, so you can run `git` commands there
+  as well.
+
 ### Fixed bugs
 
 * Error on `trunk()` revset resolution is now handled gracefully.

cli/Cargo.toml

@@ -102,6 +102,7 @@ async-trait = { workspace = true }
 insta = { workspace = true }
 test-case = { workspace = true }
 testutils = { workspace = true }
+prost = { workspace = true }
 # https://github.com/rust-lang/cargo/issues/2911#issuecomment-1483256987
 jj-cli = { path = ".", features = ["test-fakes"], default-features = false }
 

cli/src/cli_util.rs

@@ -382,7 +382,12 @@ impl CommandHelper {
         let op_head = self.resolve_operation(ui, workspace.repo_loader())?;
         let repo = workspace.repo_loader().load_at(&op_head)?;
         let env = self.workspace_environment(ui, &workspace)?;
-        revset_util::warn_unresolvable_trunk(ui, repo.as_ref(), &env.revset_parse_context())?;
+        revset_util::warn_unresolvable_trunk(
+            ui,
+            repo.as_ref(),
+            &env.revset_parse_context(),
+            workspace.workspace_id(),
+        )?;
         WorkspaceCommandHelper::new(ui, workspace, repo, env, self.is_at_head_operation())
     }
 
@@ -645,7 +650,7 @@ impl WorkspaceCommandEnvironment {
         &self.workspace_id
     }
 
-    pub(crate) fn revset_parse_context(&self) -> RevsetParseContext {
+    pub fn revset_parse_context(&self) -> RevsetParseContext {
         let workspace_context = RevsetWorkspaceContext {
             path_converter: &self.path_converter,
             workspace_id: &self.workspace_id,
@@ -669,7 +674,10 @@ impl WorkspaceCommandEnvironment {
     /// Creates fresh new context which manages cache of short commit/change ID
     /// prefixes. New context should be created per repo view (or operation.)
     pub fn new_id_prefix_context(&self) -> IdPrefixContext {
-        let context = IdPrefixContext::new(self.command.revset_extensions().clone());
+        let context = IdPrefixContext::new(
+            self.command.revset_extensions().clone(),
+            Some(self.workspace_id().clone()),
+        );
         match &self.short_prefixes_expression {
             None => context,
             Some(expression) => context.disambiguate_within(expression.clone()),
@@ -747,7 +755,10 @@ impl WorkspaceCommandEnvironment {
         // Not using self.id_prefix_context() because the disambiguation data
         // must not be calculated and cached against arbitrary repo. It's also
         // unlikely that the immutable expression contains short hashes.
-        let id_prefix_context = IdPrefixContext::new(self.command.revset_extensions().clone());
+        let id_prefix_context = IdPrefixContext::new(
+            self.command.revset_extensions().clone(),
+            Some(self.workspace_id.clone()),
+        );
         let to_rewrite_revset =
             RevsetExpression::commits(commits.into_iter().cloned().collect_vec());
         let mut expression = RevsetExpressionEvaluator::new(
@@ -898,7 +909,7 @@ impl WorkspaceCommandHelper {
     }
 
     /// Snapshot the working copy if allowed, and import Git refs if the working
-    /// copy is collocated with Git.
+    /// copy is colocated with Git.
     #[instrument(skip_all)]
     pub fn maybe_snapshot(&mut self, ui: &Ui) -> Result<(), CommandError> {
         if self.may_update_working_copy {
@@ -928,8 +939,10 @@ impl WorkspaceCommandHelper {
     fn import_git_head(&mut self, ui: &Ui) -> Result<(), CommandError> {
         assert!(self.may_update_working_copy);
         let command = self.env.command.clone();
+        let workspace_id = self.workspace_id().clone();
+        let git_repo = self.git_either_colocated_or_backend()?;
         let mut tx = self.start_transaction();
-        git::import_head(tx.repo_mut())?;
+        git::import_head(tx.repo_mut(), &git_repo, &workspace_id)?;
         if !tx.repo().has_changes() {
             return Ok(());
         }
@@ -945,8 +958,9 @@ impl WorkspaceCommandHelper {
         //   out yet.
 
         let mut tx = tx.into_inner();
-        let old_git_head = self.repo().view().git_head().clone();
-        let new_git_head = tx.repo().view().git_head().clone();
+        let workspace_id = self.workspace_id();
+        let old_git_head = self.repo().view().git_head(workspace_id).clone();
+        let new_git_head = tx.repo().view().git_head(workspace_id).clone();
         if let Some(new_git_head_id) = new_git_head.as_normal() {
             let workspace_id = self.workspace_id().to_owned();
             let new_git_head_commit = tx.repo().store().get_commit(new_git_head_id)?;
@@ -1074,6 +1088,36 @@ impl WorkspaceCommandHelper {
         self.working_copy_shared_with_git
     }
 
+    pub fn open_colocated_git_worktree_git2(
+        &self,
+    ) -> Result<Option<git2::Repository>, git2::Error> {
+        self.working_copy_shared_with_git()
+            .then_some(self.workspace_root())
+            .map(git2::Repository::open)
+            .transpose()
+    }
+
+    pub fn open_colocated_git_worktree_gix(
+        &self,
+    ) -> Result<Option<gix::Repository>, Box<gix::open::Error>> {
+        self.working_copy_shared_with_git()
+            .then_some(self.workspace_root())
+            .map(gix::open)
+            .transpose()
+            .map_err(Box::new)
+    }
+
+    pub fn git_either_colocated_or_backend(&self) -> Result<gix::Repository, CommandError> {
+        self.open_colocated_git_worktree_gix()
+            .map_err(user_error)
+            .transpose()
+            .unwrap_or_else(|| {
+                self.git_backend()
+                    .ok_or_else(|| user_error("JJ repo is not backed by git"))
+                    .map(|g| g.git_repo())
+            })
+    }
+
     pub fn format_file_path(&self, file: &RepoPath) -> String {
         self.path_converter().format_file_path(file)
     }
@@ -1748,10 +1792,9 @@ See https://martinvonz.github.io/jj/latest/working-copy/#stale-working-copy \
             .map(|commit_id| tx.repo().store().get_commit(commit_id))
             .transpose()?;
 
-        if self.working_copy_shared_with_git {
-            let git_repo = self.git_backend().unwrap().open_git_repo()?;
+        if let Some(git_worktree) = self.open_colocated_git_worktree_git2()? {
             if let Some(wc_commit) = &maybe_new_wc_commit {
-                git::reset_head(tx.repo_mut(), &git_repo, wc_commit)?;
+                git::reset_head(tx.repo_mut(), &git_worktree, self.workspace_id(), wc_commit)?;
             }
             let refs = git::export_refs(tx.repo_mut())?;
             print_failed_git_export(ui, &refs)?;

cli/src/commands/bench.rs

@@ -223,8 +223,12 @@ fn bench_revset<M: Measurement>(
     let routine = |workspace_command: &WorkspaceCommandHelper, expression: Rc<RevsetExpression>| {
         // Evaluate the expression without parsing/evaluating short-prefixes.
         let repo = workspace_command.repo().as_ref();
-        let symbol_resolver =
-            DefaultSymbolResolver::new(repo, &([] as [Box<dyn SymbolResolverExtension>; 0]));
+        let workspace_id = workspace_command.workspace_id();
+        let symbol_resolver = DefaultSymbolResolver::new(
+            repo,
+            &([] as [Box<dyn SymbolResolverExtension>; 0]),
+            Some(workspace_id),
+        );
         let resolved = expression
             .resolve_user_expression(repo, &symbol_resolver)
             .unwrap();

cli/src/commands/git/clone.rs

@@ -35,7 +35,7 @@ use crate::commands::git::map_git_error;
 use crate::commands::git::maybe_add_gitignore;
 use crate::config::write_config_value_to_file;
 use crate::config::ConfigNamePathBuf;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::git_util::print_git_import_stats;
 use crate::git_util::with_remote_git_callbacks;
 use crate::ui::Ui;
@@ -204,7 +204,7 @@ fn do_git_clone(
     } else {
         Workspace::init_internal_git(command.settings(), wc_path)?
     };
-    let git_repo = get_git_repo(repo.store())?;
+    let git_repo = get_git_backend_repo(repo.store())?;
     writeln!(
         ui.status(),
         r#"Fetching into new repo in "{}""#,

cli/src/commands/git/fetch.rs

@@ -27,7 +27,7 @@ use crate::command_error::user_error_with_hint;
 use crate::command_error::CommandError;
 use crate::commands::git::get_single_remote;
 use crate::commands::git::map_git_error;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::git_util::print_git_import_stats;
 use crate::git_util::with_remote_git_callbacks;
 use crate::ui::Ui;
@@ -60,7 +60,7 @@ pub fn cmd_git_fetch(
     args: &GitFetchArgs,
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
-    let git_repo = get_git_repo(workspace_command.repo().store())?;
+    let git_repo = get_git_backend_repo(workspace_command.repo().store())?;
     let remotes = if args.all_remotes {
         get_all_remotes(&git_repo)?
     } else if args.remotes.is_empty() {

cli/src/commands/git/import.rs

@@ -32,10 +32,12 @@ pub fn cmd_git_import(
     _args: &GitImportArgs,
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
+    let workspace_id = workspace_command.workspace_id().clone();
+    let git_repo = workspace_command.git_either_colocated_or_backend()?;
     let mut tx = workspace_command.start_transaction();
     // In non-colocated repo, HEAD@git will never be moved internally by jj.
     // That's why cmd_git_export() doesn't export the HEAD ref.
-    git::import_head(tx.repo_mut())?;
+    git::import_head(tx.repo_mut(), &git_repo, &workspace_id)?;
     let stats = git::import_refs(tx.repo_mut(), &command.settings().git_settings())?;
     print_git_import_stats(ui, tx.repo(), &stats, true)?;
     tx.finish(ui, "import git refs")?;

cli/src/commands/git/init.rs

@@ -36,7 +36,7 @@ use crate::command_error::CommandError;
 use crate::commands::git::maybe_add_gitignore;
 use crate::config::write_config_value_to_file;
 use crate::config::ConfigNamePathBuf;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::git_util::is_colocated_git_workspace;
 use crate::git_util::print_failed_git_export;
 use crate::git_util::print_git_import_stats;
@@ -174,9 +174,17 @@ pub fn do_init(
             workspace_command.maybe_snapshot(ui)?;
             maybe_set_repository_level_trunk_alias(ui, &workspace_command)?;
             if !workspace_command.working_copy_shared_with_git() {
+                let workspace_id = workspace_command.workspace_id().clone();
+                let git_repo = workspace_command.git_either_colocated_or_backend()?;
                 let mut tx = workspace_command.start_transaction();
-                jj_lib::git::import_head(tx.repo_mut())?;
-                if let Some(git_head_id) = tx.repo().view().git_head().as_normal().cloned() {
+                jj_lib::git::import_head(tx.repo_mut(), &git_repo, &workspace_id)?;
+                if let Some(git_head_id) = tx
+                    .repo()
+                    .view()
+                    .git_head(&workspace_id)
+                    .as_normal()
+                    .cloned()
+                {
                     let git_head_commit = tx.repo().store().get_commit(&git_head_id)?;
                     tx.check_out(&git_head_commit)?;
                 }
@@ -237,7 +245,7 @@ pub fn maybe_set_repository_level_trunk_alias(
     ui: &Ui,
     workspace_command: &WorkspaceCommandHelper,
 ) -> Result<(), CommandError> {
-    let git_repo = get_git_repo(workspace_command.repo().store())?;
+    let git_repo = get_git_backend_repo(workspace_command.repo().store())?;
     if let Ok(reference) = git_repo.find_reference("refs/remotes/origin/HEAD") {
         if let Some(reference_name) = reference.symbolic_target() {
             if let Some(RefName::RemoteBranch {

cli/src/commands/git/push.rs

@@ -48,7 +48,7 @@ use crate::command_error::CommandError;
 use crate::commands::git::get_single_remote;
 use crate::commands::git::map_git_error;
 use crate::formatter::Formatter;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::git_util::with_remote_git_callbacks;
 use crate::git_util::GitSidebandProgressMessageWriter;
 use crate::ui::Ui;
@@ -143,7 +143,7 @@ pub fn cmd_git_push(
     args: &GitPushArgs,
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
-    let git_repo = get_git_repo(workspace_command.repo().store())?;
+    let git_repo = get_git_backend_repo(workspace_command.repo().store())?;
 
     let remote = if let Some(name) = &args.remote {
         name.clone()

cli/src/commands/git/remote/add.rs

@@ -17,7 +17,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// Add a Git remote
@@ -36,7 +36,7 @@ pub fn cmd_git_remote_add(
 ) -> Result<(), CommandError> {
     let workspace_command = command.workspace_helper(ui)?;
     let repo = workspace_command.repo();
-    let git_repo = get_git_repo(repo.store())?;
+    let git_repo = get_git_backend_repo(repo.store())?;
     git::add_remote(&git_repo, &args.remote, &args.url)?;
     Ok(())
 }

cli/src/commands/git/remote/list.rs

@@ -18,7 +18,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// List Git remotes
@@ -32,7 +32,7 @@ pub fn cmd_git_remote_list(
 ) -> Result<(), CommandError> {
     let workspace_command = command.workspace_helper(ui)?;
     let repo = workspace_command.repo();
-    let git_repo = get_git_repo(repo.store())?;
+    let git_repo = get_git_backend_repo(repo.store())?;
     for remote_name in git_repo.remotes()?.iter().flatten() {
         let remote = git_repo.find_remote(remote_name)?;
         writeln!(

cli/src/commands/git/remote/remove.rs

@@ -17,7 +17,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// Remove a Git remote and forget its bookmarks
@@ -34,7 +34,7 @@ pub fn cmd_git_remote_remove(
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
     let repo = workspace_command.repo();
-    let git_repo = get_git_repo(repo.store())?;
+    let git_repo = get_git_backend_repo(repo.store())?;
     let mut tx = workspace_command.start_transaction();
     git::remove_remote(tx.repo_mut(), &git_repo, &args.remote)?;
     if tx.repo().has_changes() {

cli/src/commands/git/remote/rename.rs

@@ -17,7 +17,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// Rename a Git remote
@@ -36,7 +36,7 @@ pub fn cmd_git_remote_rename(
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
     let repo = workspace_command.repo();
-    let git_repo = get_git_repo(repo.store())?;
+    let git_repo = get_git_backend_repo(repo.store())?;
     let mut tx = workspace_command.start_transaction();
     git::rename_remote(tx.repo_mut(), &git_repo, &args.old, &args.new)?;
     if tx.repo().has_changes() {

cli/src/commands/git/remote/set_url.rs

@@ -17,7 +17,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// Set the URL of a Git remote
@@ -36,7 +36,7 @@ pub fn cmd_git_remote_set_url(
 ) -> Result<(), CommandError> {
     let workspace_command = command.workspace_helper(ui)?;
     let repo = workspace_command.repo();
-    let git_repo = get_git_repo(repo.store())?;
+    let git_repo = get_git_backend_repo(repo.store())?;
     git::set_remote_url(&git_repo, &args.remote, &args.url)?;
     Ok(())
 }

cli/src/commands/operation/mod.rs

@@ -100,7 +100,7 @@ fn view_with_desired_portions_restored(
         tags: repo_source.tags.clone(),
         remote_views: remote_source.remote_views.clone(),
         git_refs: current_view.git_refs.clone(),
-        git_head: current_view.git_head.clone(),
+        git_heads: current_view.git_heads.clone(),
         wc_commit_ids: repo_source.wc_commit_ids.clone(),
     }
 }