Record merge progress durably and finish pushed merges at startup

2026-10-16 13:01:17 -07:00
parent 51dfbf78a0
commit d9e0498d10
6 changed files with 211 additions and 42 deletions
@@ -136,26 +136,82 @@ func (m *Manager) recoverMerges(ctx context.Context) error {
 }

 func (m *Manager) recoverFinalizing(ctx context.Context) error {
-	finalizing, err := m.store.FinalizingTasks(ctx)
+	finalizing, err := m.store.FinalizingMerges(ctx)
 	if err != nil {
 		return err
 	}

-	for _, t := range finalizing {
-		err = m.store.ClearFinalizing(ctx, t.Id)
+	for _, f := range finalizing {
+		ferr := m.resumeFinalizing(ctx, f)
+		if ferr == nil {
+			slog.Info("finished merge at startup", "task", f.Task.Id, "commit", f.Commit)
+			continue
+		}
+
+		slog.Error("finish merge at startup", "task", f.Task.Id, "err", ferr)
+		unfinished := &unfinishedMergeError{}
+		if !errors.As(ferr, &unfinished) {
+			err = m.store.ClearFinalizing(ctx, f.Task.Id)
+			if err != nil {
+				return err
+			}
+		}
+		sessions, err := m.store.ListSessions(ctx, f.Task.Id)
 		if err != nil {
 			return err
 		}
-		sessions, err := m.store.ListSessions(ctx, t.Id)
-		if err != nil {
-			return err
-		}
-		slog.Error("merge was finishing at startup", "task", t.Id)
-		m.fileTaskError(ctx, t, sessions, "byre restarted while finishing this task's merge, so it may not have been pushed, or the task's worktree may be gone. Check the default branch before merging again.")
+		m.fileTaskError(ctx, f.Task, sessions, "byre restarted while finishing this task's merge: "+ferr.Error()+".")
 	}
 	return nil
 }

+func (m *Manager) resumeFinalizing(ctx context.Context, f store.FinalizingMerge) error {
+	project, err := m.store.GetProject(ctx, f.Task.ProjectId)
+	if err != nil {
+		return err
+	}
+	if f.Unchanged {
+		return m.closeUnchanged(ctx, f.Task, project, f.By)
+	}
+	if f.Commit == "" {
+		return errors.New("nothing was pushed. Merge again to retry")
+	}
+
+	landed, err := pushLanded(project, f.Commit)
+	if err != nil {
+		return err
+	}
+	if !landed {
+		return fmt.Errorf("its squash commit %s is not on %s/%s, so the push didn't land. Merge again to retry", f.Commit, git.Remote, project.DefaultBranch)
+	}
+	return m.closePushed(ctx, f.Task, project, f.Commit, f.Notes, f.By)
+}
+
+func pushLanded(project api.Project, commit string) (bool, error) {
+	target := git.Remote + "/" + project.DefaultBranch
+	err := git.Fetch(project.RepoPath)
+	if err != nil {
+		return false, &unfinishedMergeError{fmt.Errorf("checking whether %s reached %s failed: %w", commit, target, err)}
+	}
+	landed, err := git.IsAncestor(project.RepoPath, commit, target)
+	if err != nil {
+		return false, &unfinishedMergeError{fmt.Errorf("checking whether %s reached %s failed: %w", commit, target, err)}
+	}
+	return landed, nil
+}
+
+type unfinishedMergeError struct {
+	err error
+}
+
+func (e *unfinishedMergeError) Error() string {
+	return e.err.Error() + "; byre finishes the merge when it next starts"
+}
+
+func (e *unfinishedMergeError) Unwrap() error {
+	return e.err
+}
+
 func (m *Manager) startHeldMerges(ctx context.Context) {
 	projects, err := m.store.ProjectsWithQueuedMerges(ctx)
 	if err != nil {
@@ -274,6 +330,11 @@ func (m *Manager) finishMerge(l *live, login string) {
 	}

 	slog.Error("finish merge", "task", l.taskID, "err", err)
+	unfinished := &unfinishedMergeError{}
+	if errors.As(err, &unfinished) {
+		m.fileError(l, "Merging the task failed: "+err.Error()+".")
+		return
+	}
 	cerr := m.store.ClearFinalizing(ctx, l.taskID)
 	if cerr != nil {
 		slog.Error("clear merge finalizing", "task", l.taskID, "err", cerr)
@@ -315,38 +376,74 @@ func (m *Manager) squashAndClose(ctx context.Context, taskID, login string) erro
 		return err
 	}

-	pushed := ""
-	if commit != "" {
-		note, err := m.mergeNote(ctx, task, login)
+	if commit == "" {
+		err = m.store.SetFinalizingUnchanged(ctx, taskID)
 		if err != nil {
 			return err
 		}
-		notes, err := git.NoteCommit(project.RepoPath, commit, note, env)
-		if err != nil {
-			return err
-		}
-		err = git.Push(project.RepoPath, commit, project.DefaultBranch, notes)
-		if err != nil {
-			return err
-		}
-		pushed = git.Remote + "/" + project.DefaultBranch
-		err = git.SetNotes(project.RepoPath, notes)
-		if err != nil {
-			return fmt.Errorf("pushed %s to %s, but updating %s in the project checkout failed: %w", commit, pushed, git.NotesRef, err)
-		}
-		err = git.FastForward(project.RepoPath, commit)
-		if err != nil {
-			return fmt.Errorf("pushed %s to %s, but fast-forwarding the project checkout failed: %w", commit, pushed, err)
-		}
+		return m.closeUnchanged(ctx, task, project, login)
 	}

-	err = m.RemoveTask(ctx, task, project, login)
+	note, err := m.mergeNote(ctx, task, login)
 	if err != nil {
 		return err
 	}
+	notes, err := git.NoteCommit(project.RepoPath, commit, note, env)
+	if err != nil {
+		return err
+	}
+	err = m.store.SetFinalizingCommit(ctx, taskID, commit, notes)
+	if err != nil {
+		return err
+	}
+	err = git.Push(project.RepoPath, commit, project.DefaultBranch, notes)
+	if errors.Is(err, git.ErrRemoteMoved) {
+		return err
+	}
+	if err != nil {
+		landed, lerr := pushLanded(project, commit)
+		if lerr != nil {
+			return &unfinishedMergeError{fmt.Errorf("%w, and %w", err, errors.Unwrap(lerr))}
+		}
+		if !landed {
+			return err
+		}
+		slog.Warn("push reported failure but landed", "task", taskID, "commit", commit, "err", err)
+	}
+	return m.closePushed(ctx, task, project, commit, notes, login)
+}

-	_, err = m.store.MergeTask(ctx, taskID, commit, pushed, login)
-	return err
+func (m *Manager) closeUnchanged(ctx context.Context, task api.Task, project api.Project, login string) error {
+	err := m.RemoveTask(ctx, task, project, login)
+	if err != nil {
+		return &unfinishedMergeError{fmt.Errorf("the merge changed nothing, but removing the task's worktree failed: %w", err)}
+	}
+	_, err = m.store.MergeTask(ctx, task.Id, "", "", login)
+	if err != nil {
+		return &unfinishedMergeError{fmt.Errorf("the merge changed nothing, but closing the task failed: %w", err)}
+	}
+	return nil
+}
+
+func (m *Manager) closePushed(ctx context.Context, task api.Task, project api.Project, commit, notes, login string) error {
+	pushed := git.Remote + "/" + project.DefaultBranch
+	err := git.AdvanceNotes(project.RepoPath, notes)
+	if err != nil {
+		return &unfinishedMergeError{fmt.Errorf("pushed %s to %s, but updating %s in the project checkout failed: %w", commit, pushed, git.NotesRef, err)}
+	}
+	err = git.FastForward(project.RepoPath, commit)
+	if err != nil {
+		return &unfinishedMergeError{fmt.Errorf("pushed %s to %s, but fast-forwarding the project checkout failed: %w", commit, pushed, err)}
+	}
+	err = m.RemoveTask(ctx, task, project, login)
+	if err != nil {
+		return &unfinishedMergeError{fmt.Errorf("pushed %s to %s, but removing the task's worktree failed: %w", commit, pushed, err)}
+	}
+	_, err = m.store.MergeTask(ctx, task.Id, commit, pushed, login)
+	if err != nil {
+		return &unfinishedMergeError{fmt.Errorf("pushed %s to %s, but closing the task failed: %w", commit, pushed, err)}
+	}
+	return nil
 }

 func (m *Manager) CoAuthors(ctx context.Context, taskID, login string) ([]api.Participant, error) {