Hold a task's merge while another task in the project is merging

internal/store/store.go

@@ -268,6 +268,9 @@ UPDATE tasks SET port_base = (
 	SELECT 41000 + 10 * (count(*) - 1) FROM tasks AS earlier
 	WHERE earlier.status = 'active' AND (earlier.created_at < tasks.created_at OR (earlier.created_at = tasks.created_at AND earlier.id <= tasks.id))
 ) WHERE status = 'active' AND port_base = 0;
+`}, {"add-task-merge-queue", `
+ALTER TABLE tasks ADD COLUMN merge_queued_by TEXT NOT NULL DEFAULT '';
+ALTER TABLE tasks ADD COLUMN merge_queued_at TEXT NOT NULL DEFAULT '';
 `}}
 
 const (
@@ -570,21 +573,7 @@ func (s *Store) CreateTask(ctx context.Context, t api.Task, actor string) error
 }
 
 func (s *Store) ListTasks(ctx context.Context, projectID string) ([]api.Task, error) {
-	rows, err := s.db.QueryContext(ctx, `SELECT `+taskColumns+` FROM tasks WHERE project_id = ? ORDER BY created_at DESC`, projectID)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-
-	tasks := []api.Task{}
-	for rows.Next() {
-		t, err := scanTask(rows)
-		if err != nil {
-			return nil, err
-		}
-		tasks = append(tasks, t)
-	}
-	return tasks, rows.Err()
+	return s.queryTasks(ctx, `SELECT `+taskColumns+` FROM tasks WHERE project_id = ? ORDER BY created_at DESC`, projectID)
 }
 
 func (s *Store) GetTask(ctx context.Context, id string) (api.Task, error) {
@@ -633,6 +622,90 @@ func (s *Store) TakeMergingBy(ctx context.Context, id string) (string, error) {
 	return login, err
 }
 
+func (s *Store) MergingTasks(ctx context.Context) ([]api.Task, error) {
+	return s.queryTasks(ctx, `SELECT `+taskColumns+` FROM tasks WHERE status = ? AND merging_by != ''`, string(api.TaskStatusActive))
+}
+
+func (s *Store) QueuedMerges(ctx context.Context, projectID string) ([]api.Task, error) {
+	return s.queryTasks(ctx, `SELECT `+taskColumns+` FROM tasks WHERE project_id = ? AND status = ? AND merge_queued_by != '' ORDER BY merge_queued_at`,
+		projectID, string(api.TaskStatusActive))
+}
+
+func (s *Store) ProjectsWithQueuedMerges(ctx context.Context) ([]string, error) {
+	rows, err := s.db.QueryContext(ctx, `SELECT DISTINCT project_id FROM tasks WHERE status = ? AND merge_queued_by != ''`, string(api.TaskStatusActive))
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	ids := []string{}
+	for rows.Next() {
+		id := ""
+		err = rows.Scan(&id)
+		if err != nil {
+			return nil, err
+		}
+		ids = append(ids, id)
+	}
+	return ids, rows.Err()
+}
+
+func (s *Store) queryTasks(ctx context.Context, query string, args ...any) ([]api.Task, error) {
+	rows, err := s.db.QueryContext(ctx, query, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	tasks := []api.Task{}
+	for rows.Next() {
+		t, err := scanTask(rows)
+		if err != nil {
+			return nil, err
+		}
+		tasks = append(tasks, t)
+	}
+	return tasks, rows.Err()
+}
+
+func (s *Store) QueueMerge(ctx context.Context, id, login string) error {
+	return s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
+		projectID := ""
+		err := tx.QueryRowContext(ctx, `UPDATE tasks SET merge_queued_by = ?, merge_queued_at = ? WHERE id = ? AND status = ? AND merge_queued_by = '' RETURNING project_id`,
+			login, now(), id, string(api.TaskStatusActive)).Scan(&projectID)
+		if errors.Is(err, sql.ErrNoRows) {
+			return ErrNotFound
+		}
+		if err != nil {
+			return err
+		}
+		return emit(api.Event{Kind: "task.merge_queued", ProjectId: &projectID, TaskId: &id, Actor: login, Payload: map[string]any{"id": id}})
+	})
+}
+
+func (s *Store) TakeQueuedMerge(ctx context.Context, id string) (string, error) {
+	login := ""
+	err := s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
+		projectID := ""
+		err := tx.QueryRowContext(ctx, `SELECT project_id, merge_queued_by FROM tasks WHERE id = ?`, id).Scan(&projectID, &login)
+		if errors.Is(err, sql.ErrNoRows) {
+			return ErrNotFound
+		}
+		if err != nil {
+			return err
+		}
+		if login == "" {
+			return nil
+		}
+		_, err = tx.ExecContext(ctx, `UPDATE tasks SET merge_queued_by = '', merge_queued_at = '' WHERE id = ?`, id)
+		if err != nil {
+			return err
+		}
+		return emit(api.Event{Kind: "task.merge_unqueued", ProjectId: &projectID, TaskId: &id, Actor: "byre", Payload: map[string]any{"id": id}})
+	})
+	return login, err
+}
+
 func (s *Store) MergeTask(ctx context.Context, id, commit, pushed, actor string) (api.Task, error) {
 	return s.closeTask(ctx, id, api.TaskStatusMerged, commit, actor, "task.merged", map[string]any{"id": id, "commit": commit, "pushed": pushed})
 }
@@ -1007,7 +1080,7 @@ func (s *Store) write(ctx context.Context, fn func(tx *sql.Tx, emit emitFunc) er
 
 const projectColumns = `id, name, repo_path, default_branch, remote, created_by, created_at`
 
-const taskColumns = `id, project_id, title, merge_title, branch, worktree_path, base_ref, port_base, status, created_by, created_at, closed_at, merge_commit, todo_item, forked_from, forked_at`
+const taskColumns = `id, project_id, title, merge_title, branch, worktree_path, base_ref, port_base, status, created_by, created_at, closed_at, merge_commit, todo_item, forked_from, forked_at, merge_queued_at`
 
 const sessionColumns = `id, coalesce(task_id, ''), owner, vendor, model, vendor_session_id, state, role, created_by, created_at, forked_from, forked_at`
 
@@ -1035,7 +1108,8 @@ func scanTask(row scanner) (api.Task, error) {
 	todoItem := ""
 	forkedFrom := ""
 	forkedAt := 0
-	err := row.Scan(&t.Id, &t.ProjectId, &t.Title, &t.MergeTitle, &t.Branch, &t.WorktreePath, &t.BaseRef, &t.PortBase, &status, &t.CreatedBy, &createdAt, &closedAt, &mergeCommit, &todoItem, &forkedFrom, &forkedAt)
+	mergeQueuedAt := ""
+	err := row.Scan(&t.Id, &t.ProjectId, &t.Title, &t.MergeTitle, &t.Branch, &t.WorktreePath, &t.BaseRef, &t.PortBase, &status, &t.CreatedBy, &createdAt, &closedAt, &mergeCommit, &todoItem, &forkedFrom, &forkedAt, &mergeQueuedAt)
 	if err != nil {
 		return t, err
 	}
@@ -1064,6 +1138,13 @@ func scanTask(row scanner) (api.Task, error) {
 		t.ForkedFrom = &forkedFrom
 		t.ForkedAt = &forkedAt
 	}
+	if mergeQueuedAt != "" {
+		qt, err := parseTime(mergeQueuedAt)
+		if err != nil {
+			return t, err
+		}
+		t.MergeQueuedAt = &qt
+	}
 	return t, nil
 }