SERVER-24418 Make Message and BufBuilder use SharedBuffer for memory management

This makes it possible to get owned BSONObj out of a Message without copying.

Hooked up to the following places:
- Anything using the Fetcher (including oplog fetching on secondaries)
- Anything using DBClientInterface::findOne()
- Anything using CursorResponse (including Sharded queries)

As a simplification, Messages no longer support non-contiguous buffers, or
non-owning buffers. The former wasn't used by anything, and the latter was
only used by mongosniff only for messages that fit in a single packet.

1 files changed, 0 insertions, 3 deletions

diff --git a/src/mongo/db/dbdirectclient.cpp b/src/mongo/db/dbdirectclient.cpp
index 763b6e3dde2..06c06991722 100644
--- a/src/mongo/db/dbdirectclient.cpp
+++ b/src/mongo/db/dbdirectclient.cpp
@@ -126,9 +126,6 @@ bool DBDirectClient::call(Message& toSend, Message& response, bool assertOk, str
     CurOp curOp(_txn);
     assembleResponse(_txn, toSend, dbResponse, dummyHost);
     verify(!dbResponse.response.empty());
-
-    // can get rid of this if we make response handling smarter
-    dbResponse.response.concat();
     response = std::move(dbResponse.response);
 
     return true;