SERVER-20884 build command replies in-place to avoid copies

1 files changed, 1 insertions, 21 deletions

diff --git a/src/mongo/rpc/legacy_reply.cpp b/src/mongo/rpc/legacy_reply.cpp
index 60d68008558..e298a97814f 100644
--- a/src/mongo/rpc/legacy_reply.cpp
+++ b/src/mongo/rpc/legacy_reply.cpp
@@ -67,27 +67,7 @@ LegacyReply::LegacyReply(const Message* message) : _message(std::move(message))
     std::tie(_commandReply, _metadata) =
         uassertStatusOK(rpc::upconvertReplyMetadata(BSONObj(qr.data())));
 
-    // Copy the bson array of documents from the message into
-    // a contiguous area of memory owned by _docBuffer so
-    // DocumentRange can be used to iterate over documents
-    auto cursorElem = _commandReply[LegacyReplyBuilder::kCursorTag];
-    if (cursorElem.eoo())
-        return;
-
-    BSONObj cursorObj = cursorElem.Obj();
-    auto firstBatchElem = cursorObj[LegacyReplyBuilder::kFirstBatchTag];
-    if (firstBatchElem.eoo())
-        return;
-
-    for (BSONObjIterator it(firstBatchElem.Obj()); it.more(); it.next()) {
-        invariant((*it).isABSONObj());
-        BSONObj doc = (*it).Obj();
-        doc.appendSelfToBufBuilder(_docBuffer);
-    }
-    const char* dataBegin = _docBuffer.buf();
-    const char* dataEnd = dataBegin + _docBuffer.len();
-    _outputDocs = DocumentRange(dataBegin, dataEnd);
-
+    _outputDocs = DocumentRange{};
     return;
 }