SERVER-20609 do not heap allocate Message

7 files changed, 29 insertions, 43 deletions

diff --git a/src/mongo/db/db.cpp b/src/mongo/db/db.cpp
index 4f2d3676f19..ce1a9bfc4a3 100644
--- a/src/mongo/db/db.cpp
+++ b/src/mongo/db/db.cpp
@@ -173,10 +173,10 @@ public:
                 // results after the response reaches the client
             }
 
-            if (dbresponse.response) {
-                port->reply(m, *dbresponse.response, dbresponse.responseTo);
+            if (!dbresponse.response.empty()) {
+                port->reply(m, dbresponse.response, dbresponse.responseTo);
                 if (dbresponse.exhaustNS.size() > 0) {
-                    MsgData::View header = dbresponse.response->header();
+                    MsgData::View header = dbresponse.response.header();
                     QueryResult::View qr = header.view2ptr();
                     long long cursorid = qr.getCursorId();
                     if (cursorid) {
diff --git a/src/mongo/db/dbdirectclient.cpp b/src/mongo/db/dbdirectclient.cpp
index 244669481c5..519cade63ad 100644
--- a/src/mongo/db/dbdirectclient.cpp
+++ b/src/mongo/db/dbdirectclient.cpp
@@ -121,11 +121,11 @@ bool DBDirectClient::call(Message& toSend, Message& response, bool assertOk, str
     DbResponse dbResponse;
     CurOp curOp(_txn);
     assembleResponse(_txn, toSend, dbResponse, dummyHost);
-    verify(dbResponse.response);
+    verify(!dbResponse.response.empty());
 
     // can get rid of this if we make response handling smarter
-    dbResponse.response->concat();
-    response = std::move(*dbResponse.response);
+    dbResponse.response.concat();
+    response = std::move(dbResponse.response);
 
     return true;
 }
diff --git a/src/mongo/db/dbmessage.cpp b/src/mongo/db/dbmessage.cpp
index eb50ecb063a..5750542eb26 100644
--- a/src/mongo/db/dbmessage.cpp
+++ b/src/mongo/db/dbmessage.cpp
@@ -201,9 +201,9 @@ void replyToQuery(int queryResultFlags,
 }
 
 void replyToQuery(int queryResultFlags, Message& m, DbResponse& dbresponse, BSONObj obj) {
-    Message* resp = new Message();
-    replyToQuery(queryResultFlags, *resp, obj);
-    dbresponse.response = resp;
+    Message resp;
+    replyToQuery(queryResultFlags, resp, obj);
+    dbresponse.response = std::move(resp);
     dbresponse.responseTo = m.header().getId();
 }
 
diff --git a/src/mongo/db/dbmessage.h b/src/mongo/db/dbmessage.h
index aa74fd59ffb..2f0c6b6645b 100644
--- a/src/mongo/db/dbmessage.h
+++ b/src/mongo/db/dbmessage.h
@@ -312,16 +312,11 @@ public:
  * A response to a DbMessage.
  */
 struct DbResponse {
-    Message* response;
+    Message response;
     MSGID responseTo;
     std::string exhaustNS; /* points to ns if exhaust mode. 0=normal mode*/
-    DbResponse(Message* r, MSGID rt) : response(r), responseTo(rt) {}
-    DbResponse() {
-        response = 0;
-    }
-    ~DbResponse() {
-        delete response;
-    }
+    DbResponse(Message r, MSGID rt) : response(std::move(r)), responseTo(rt) {}
+    DbResponse() = default;
 };
 
 void replyToQuery(int queryResultFlags,
diff --git a/src/mongo/db/dbwebserver.cpp b/src/mongo/db/dbwebserver.cpp
index 1ad6e54a236..b60e1dd77c3 100644
--- a/src/mongo/db/dbwebserver.cpp
+++ b/src/mongo/db/dbwebserver.cpp
@@ -280,13 +280,13 @@ public:
             .setCommandArgs(cmdObj);
 
         auto cmdRequestMsg = requestBuilder.done();
-        rpc::CommandRequest cmdRequest{cmdRequestMsg.get()};
+        rpc::CommandRequest cmdRequest{&cmdRequestMsg};
         rpc::CommandReplyBuilder cmdReplyBuilder{};
 
         Command::execCommand(txn, c, cmdRequest, &cmdReplyBuilder);
 
         auto cmdReplyMsg = cmdReplyBuilder.done();
-        rpc::CommandReply cmdReply{cmdReplyMsg.get()};
+        rpc::CommandReply cmdReply{&cmdReplyMsg};
 
         responseCode = 200;
 
diff --git a/src/mongo/db/ftdc/SConscript b/src/mongo/db/ftdc/SConscript
index 1527dbdd5f9..b2ff0255bfb 100644
--- a/src/mongo/db/ftdc/SConscript
+++ b/src/mongo/db/ftdc/SConscript
@@ -63,4 +63,3 @@ env.CppUnitTest(
         'ftdc',
     ],
 )
-
diff --git a/src/mongo/db/instance.cpp b/src/mongo/db/instance.cpp
index 59e3bebb214..e752ae92fa6 100644
--- a/src/mongo/db/instance.cpp
+++ b/src/mongo/db/instance.cpp
@@ -260,9 +260,9 @@ static void receivedCommand(OperationContext* txn,
 
     auto response = builder.done();
 
-    op->debug().responseLength = response->header().dataLen();
+    op->debug().responseLength = response.header().dataLen();
 
-    dbResponse.response = response.release();
+    dbResponse.response = std::move(response);
     dbResponse.responseTo = responseTo;
 }
 
@@ -301,9 +301,9 @@ void receivedRpc(OperationContext* txn, Client& client, DbResponse& dbResponse,
 
     auto response = replyBuilder.done();
 
-    curOp->debug().responseLength = response->header().dataLen();
+    curOp->debug().responseLength = response.header().dataLen();
 
-    dbResponse.response = response.release();
+    dbResponse.response = std::move(response);
     dbResponse.responseTo = responseTo;
 }
 
@@ -378,7 +378,6 @@ static void receivedQuery(OperationContext* txn,
 
     DbMessage d(m);
     QueryMessage q(d);
-    unique_ptr<Message> resp(new Message());
 
     CurOp& op = *CurOp::get(txn);
 
@@ -388,16 +387,13 @@ static void receivedQuery(OperationContext* txn,
         audit::logQueryAuthzCheck(client, nss, q.query, status.code());
         uassertStatusOK(status);
 
-        dbResponse.exhaustNS = runQuery(txn, q, nss, *resp);
-        verify(!resp->empty());
+        dbResponse.exhaustNS = runQuery(txn, q, nss, dbResponse.response);
     } catch (const AssertionException& exception) {
-        resp.reset(new Message());
-        generateLegacyQueryErrorResponse(&exception, q, &op, resp.get());
+        dbResponse.response.reset();
+        generateLegacyQueryErrorResponse(&exception, q, &op, &dbResponse.response);
     }
 
-    op.debug().responseLength = resp->header().dataLen();
-
-    dbResponse.response = resp.release();
+    op.debug().responseLength = dbResponse.response.header().dataLen();
     dbResponse.responseTo = responseTo;
 }
 
@@ -536,13 +532,11 @@ void assembleResponse(OperationContext* txn,
             log(LogComponent::kQuery) << curTimeMillis64() % 10000
                                       << " long msg received, len:" << len << endl;
 
-        Message* resp = new Message();
         if (strcmp("end", p) == 0)
-            resp->setData(opReply, "dbMsg end no longer supported");
+            dbresponse.response.setData(opReply, "dbMsg end no longer supported");
         else
-            resp->setData(opReply, "i am fine - dbMsg deprecated");
+            dbresponse.response.setData(opReply, "i am fine - dbMsg deprecated");
 
-        dbresponse.response = resp;
         dbresponse.responseTo = m.header().getId();
     } else {
         try {
@@ -923,17 +917,15 @@ bool receivedGetMore(OperationContext* txn, DbResponse& dbresponse, Message& m,
         curop.debug().exceptionInfo = e.getInfo();
 
         replyToQuery(ResultFlag_ErrSet, m, dbresponse, errObj);
-        curop.debug().responseLength = dbresponse.response->header().dataLen();
+        curop.debug().responseLength = dbresponse.response.header().dataLen();
         curop.debug().nreturned = 1;
         return false;
     }
 
-    Message* resp = new Message();
-    resp->setData(msgdata.view2ptr(), true);
-    curop.debug().responseLength = resp->header().dataLen();
+    dbresponse.response.setData(msgdata.view2ptr(), true);
+    curop.debug().responseLength = dbresponse.response.header().dataLen();
     curop.debug().nreturned = msgdata.getNReturned();
 
-    dbresponse.response = resp;
     dbresponse.responseTo = m.header().getId();
 
     if (exhaust) {
@@ -1106,11 +1098,11 @@ static void insertSystemIndexes(OperationContext* txn, DbMessage& d, CurOp& curO
                                      .setMetadata(rpc::makeEmptyMetadata())
                                      .setCommandArgs(cmdObj)
                                      .done();
-            rpc::LegacyRequest cmdRequest{cmdRequestMsg.get()};
+            rpc::LegacyRequest cmdRequest{&cmdRequestMsg};
             rpc::LegacyReplyBuilder cmdReplyBuilder{};
             Command::execCommand(txn, createIndexesCmd, cmdRequest, &cmdReplyBuilder);
             auto cmdReplyMsg = cmdReplyBuilder.done();
-            rpc::LegacyReply cmdReply{cmdReplyMsg.get()};
+            rpc::LegacyReply cmdReply{&cmdReplyMsg};
             uassertStatusOK(Command::getStatusFromCommandResult(cmdReply.getCommandReply()));
         } catch (const DBException& ex) {
             LastError::get(txn->getClient()).setLastError(ex.getCode(), ex.getInfo().msg);