From e561c3995c7396cf3749ccdf6a3357d7dd32c856 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20M=C3=A4kel=C3=A4?= <markus.makela@mariadb.com>
Date: Thu, 21 Jun 2018 14:43:15 +0300
Subject: [PATCH] Use correct write in Backend::execute_session_command

Backend::execute_session_command would use the overridden write method
instead of the Backend::write method that it intended to use. This caused
session commands that did not expect a response to be in a state that
expected a result.

Also fixed RWBackend::write pass the response_type value to
Backend::write.
---
 server/core/backend.cc                        | 19 +++++++++----------
 .../routing/readwritesplit/rwsplitsession.cc  |  2 +-
 2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/server/core/backend.cc b/server/core/backend.cc
index edd1ef1cc..0a6f631d0 100644
--- a/server/core/backend.cc
+++ b/server/core/backend.cc
@@ -87,18 +87,18 @@ bool Backend::execute_session_command()
 
     CHK_DCB(m_dcb);
 
-    SessionCommandList::iterator iter = m_session_commands.begin();
-    SessionCommand& sescmd = *(*iter);
-    GWBUF *buffer = sescmd.deep_copy_buffer();
+    SSessionCommand& sescmd = m_session_commands.front();
+    GWBUF *buffer = sescmd->deep_copy_buffer();
     bool rval = false;
 
-    switch (sescmd.get_command())
+    switch (sescmd->get_command())
     {
     case MXS_COM_QUIT:
     case MXS_COM_STMT_CLOSE:
         /** These commands do not generate responses */
-        rval = write(buffer, NO_RESPONSE);
+        rval = Backend::write(buffer, NO_RESPONSE);
         complete_session_command();
+        ss_dassert(!is_waiting_result());
         break;
 
     case MXS_COM_CHANGE_USER:
@@ -109,12 +109,11 @@ bool Backend::execute_session_command()
 
     case MXS_COM_QUERY:
     default:
-        /**
-         * Mark session command buffer, it triggers writing
-         * MySQL command to protocol
-         */
+        // TODO: Remove use of GWBUF_TYPE_SESCMD
+        //Mark session command buffer, it triggers writing MySQL command to protocol
         gwbuf_set_type(buffer, GWBUF_TYPE_SESCMD);
-        rval = write(buffer);
+        rval = Backend::write(buffer);
+        ss_dassert(is_waiting_result());
         break;
     }
 
diff --git a/server/modules/routing/readwritesplit/rwsplitsession.cc b/server/modules/routing/readwritesplit/rwsplitsession.cc
index 35476403d..beeba1bbc 100644
--- a/server/modules/routing/readwritesplit/rwsplitsession.cc
+++ b/server/modules/routing/readwritesplit/rwsplitsession.cc
@@ -96,7 +96,7 @@ bool RWBackend::write(GWBUF* buffer, response_type type)
         }
     }
 
-    return mxs::Backend::write(buffer);
+    return mxs::Backend::write(buffer, type);
 }
 
 bool RWBackend::consume_fetched_rows(GWBUF* buffer)