call.cancel()
      }
    }
  }

  /**
   * Promotes eligible calls from [readyAsyncCalls] to [runningAsyncCalls] and runs them on the
   * executor service. Must not be called with synchronization because executing calls can call
   * into user code.
   *
   * @return true if the dispatcher is currently running calls.
   */
  private fun promoteAndExecute(): Boolean {