From dc338ff3f224563286edb83dfd8892ed509b2155 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20M=C3=A4kel=C3=A4?= <markus.makela@mariadb.com>
Date: Wed, 4 Apr 2018 15:38:50 +0300
Subject: [PATCH] Move causal read reply processing into sub-function

This makes the clientReply a lot easier to comprehend.
---
 .../routing/readwritesplit/rwsplitsession.cc  | 27 +++++++++++++------
 .../routing/readwritesplit/rwsplitsession.hh  |  1 +
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/server/modules/routing/readwritesplit/rwsplitsession.cc b/server/modules/routing/readwritesplit/rwsplitsession.cc
index 0c4129b11..86db378a9 100644
--- a/server/modules/routing/readwritesplit/rwsplitsession.cc
+++ b/server/modules/routing/readwritesplit/rwsplitsession.cc
@@ -383,11 +383,9 @@ static void log_unexpected_response(DCB* dcb, GWBUF* buffer)
     }
 }
 
-void RWSplitSession::clientReply(GWBUF *writebuf, DCB *backend_dcb)
+bool RWSplitSession::handle_causal_read_reply(GWBUF *writebuf, SRWBackend& backend)
 {
-    DCB *client_dcb = backend_dcb->session->client_dcb;
-
-    SRWBackend& backend = get_backend_from_dcb(backend_dcb);
+    bool rval = true;
 
     if (m_config.enable_causal_read &&
         GWBUF_IS_REPLY_OK(writebuf) &&
@@ -403,18 +401,31 @@ void RWSplitSession::clientReply(GWBUF *writebuf, DCB *backend_dcb)
 
     if (m_wait_gtid_state == EXPECTING_WAIT_GTID_RESULT)
     {
-        ss_dassert(m_config.enable_causal_read);
         if ((writebuf = discard_master_wait_gtid_result(writebuf)) == NULL)
         {
-            // Nothing to route, return
-            return;
+            rval = false;
         }
     }
-    if (m_wait_gtid_state == EXPECTING_REAL_RESULT)
+
+    if (rval && m_wait_gtid_state == EXPECTING_REAL_RESULT)
     {
         correct_packet_sequence(writebuf);
     }
 
+    return rval;
+}
+
+void RWSplitSession::clientReply(GWBUF *writebuf, DCB *backend_dcb)
+{
+    DCB *client_dcb = backend_dcb->session->client_dcb;
+
+    SRWBackend& backend = get_backend_from_dcb(backend_dcb);
+
+    if (!handle_causal_read_reply(writebuf, backend))
+    {
+        return; // Nothing to route, return
+    }
+
     if (backend->get_reply_state() == REPLY_STATE_DONE)
     {
         /** If we receive an unexpected response from the server, the internal
diff --git a/server/modules/routing/readwritesplit/rwsplitsession.hh b/server/modules/routing/readwritesplit/rwsplitsession.hh
index edaae5c56..2e30542c9 100644
--- a/server/modules/routing/readwritesplit/rwsplitsession.hh
+++ b/server/modules/routing/readwritesplit/rwsplitsession.hh
@@ -159,6 +159,7 @@ private:
     void log_master_routing_failure(bool found, mxs::SRWBackend& old_master,
                                     mxs::SRWBackend& curr_master);
 
+    bool handle_causal_read_reply(GWBUF *writebuf, mxs::SRWBackend& backend);
     GWBUF* add_prefix_wait_gtid(SERVER *server, GWBUF *origin);
     void correct_packet_sequence(GWBUF *buffer);
     GWBUF* discard_master_wait_gtid_result(GWBUF *buffer);