diff --git a/cpp/src/scheduler/TaskTable.h b/cpp/src/scheduler/TaskTable.h
index 8f367f9c1aefef6610e23f81f4b8a22432a237c0..e638abe617d44f26bbd941d9fbdf1dbc79cfcbb3 100644
--- a/cpp/src/scheduler/TaskTable.h
+++ b/cpp/src/scheduler/TaskTable.h
@@ -149,6 +149,11 @@ class TaskTable {
     }
 
  public:
+    TaskTableItemPtr& operator[](uint64_t index) {
+        std::lock_guard<std::mutex> lock(mutex_);
+        return table_[index];
+    }
+
     std::deque<TaskTableItemPtr>::iterator
     begin() {
         return table_.begin();