Method unsubscribe

include/dmlc/concurrentqueue.h:522–533

    }

    static void unsubscribe(ThreadExitListener* listener)
    {
      auto& tlsInst = instance();
      ThreadExitListener** prev = &tlsInst.tail;
      for (auto ptr = tlsInst.tail; ptr != nullptr; ptr = ptr->next) {
        if (ptr == listener) {
          *prev = ptr->next;
          break;
        }
        prev = &ptr->next;
      }
    }

  private:
    ThreadExitNotifier() : tail(nullptr) { }