xx

velox/exec/ExchangeSource.h

@@ -84,6 +84,12 @@ class ExchangeSource : public std::enable_shared_from_this<ExchangeSource> {
   virtual folly::SemiFuture<Response> requestDataSizes(
       std::chrono::microseconds maxWait) = 0;
 
+  /// Notifies that the engine needs some time to process already received data
+  /// and may not request more for a while. The implementation may choose to
+  /// release temporary buffers or pause fetching any new data until any of
+  /// the 'request' or 'requestDataSizes' methods are called.
+  virtual void pause() {};
+
   /// Close the exchange source. May be called before all data
   /// has been received and processed. This can happen in case
   /// of an error or an operator like Limit aborting the query