SERVER-33323 Refactor agg cursor merging on mongos

This commit makes it so that aggregations will always use a
$mergeCursors as a wrapper around a AsyncResultsMerger, which is new
behavior for mongos. As part of this refactor, we can delete the concept
of a 'merging presorted' $sort stage (which is now handled by the
AsyncResultsMerger) and delete the DocumentSourceRouterAdapter stage
which talked to a RouterStageMerge, instead directly using a
$mergeCursors stage.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/mongo/db/pipeline/document_source_exchange.h b/src/mongo/db/pipeline/document_source_exchange.h
index b4231424032..ba4cb56ecdb 100644
--- a/src/mongo/db/pipeline/document_source_exchange.h
+++ b/src/mongo/db/pipeline/document_source_exchange.h
@@ -167,7 +167,7 @@ public:
     boost::intrusive_ptr<DocumentSource> getShardSource() final {
         return this;
     }
-    std::list<boost::intrusive_ptr<DocumentSource>> getMergeSources() final {
+    MergingLogic mergingLogic() final {
         // TODO SERVER-35974 we have to revisit this when we implement consumers.
         return {this};
     }