From 24b438c9b69f8e1da96254846dadc2ab9dfed9b6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20M=C3=A4kel=C3=A4?= <markus.makela@mariadb.com>
Date: Tue, 25 Sep 2018 12:49:02 +0300
Subject: [PATCH] MXS-2068: Split reply_is_complete into two functions

By splitting the processing and state querying into two separate
functions, the result can be inspected multiple times without triggering
the result processing.
---
 include/maxscale/protocol/rwbackend.hh           | 12 +++++++++++-
 server/modules/protocol/MySQL/rwbackend.cc       | 16 ++++------------
 server/modules/routing/cat/catsession.cc         |  4 +++-
 .../routing/readwritesplit/rwsplitsession.cc     |  4 +++-
 4 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/include/maxscale/protocol/rwbackend.hh b/include/maxscale/protocol/rwbackend.hh
index 1f15a51e4..a72602774 100644
--- a/include/maxscale/protocol/rwbackend.hh
+++ b/include/maxscale/protocol/rwbackend.hh
@@ -104,7 +104,17 @@ public:
         return m_local_infile_requested;
     }
 
-    bool reply_is_complete(GWBUF* buffer);
+    void process_reply(GWBUF* buffer);
+
+    /**
+     * Check whether the response from the server is complete
+     *
+     * @return True if no more results are expected from this server
+     */
+    bool reply_is_complete() const
+    {
+        return m_reply_state == REPLY_STATE_DONE;
+    }
 
     // Controlled by the session
     ResponseStat& response_stat();
diff --git a/server/modules/protocol/MySQL/rwbackend.cc b/server/modules/protocol/MySQL/rwbackend.cc
index 70289a380..416716d60 100644
--- a/server/modules/protocol/MySQL/rwbackend.cc
+++ b/server/modules/protocol/MySQL/rwbackend.cc
@@ -137,14 +137,11 @@ static inline bool have_next_packet(GWBUF* buffer)
 }
 
 /**
- * @brief Check if we have received a complete reply from the backend
+ * @brief Process a possibly partial response from the backend
  *
- * @param backend Backend reference
  * @param buffer  Buffer containing the response
- *
- * @return True if the complete response has been received
  */
-bool RWBackend::reply_is_complete(GWBUF* buffer)
+void RWBackend::process_reply(GWBUF* buffer)
 {
     if (current_command() == MXS_COM_STMT_FETCH)
     {
@@ -191,9 +188,9 @@ bool RWBackend::reply_is_complete(GWBUF* buffer)
                 // TODO: Don't clone the buffer
                 GWBUF* tmp = gwbuf_clone(buffer);
                 tmp = gwbuf_consume(tmp, mxs_mysql_get_packet_len(tmp));
-                bool rval = reply_is_complete(tmp);
+                process_reply(tmp);
                 gwbuf_free(tmp);
-                return rval;
+                return;
             }
         }
     }
@@ -245,15 +242,10 @@ bool RWBackend::reply_is_complete(GWBUF* buffer)
         }
     }
 
-    bool rval = false;
-
     if (get_reply_state() == REPLY_STATE_DONE)
     {
         ack_write();
-        rval = true;
     }
-
-    return rval;
 }
 
 ResponseStat& RWBackend::response_stat()
diff --git a/server/modules/routing/cat/catsession.cc b/server/modules/routing/cat/catsession.cc
index 049b62de2..eb6c97185 100644
--- a/server/modules/routing/cat/catsession.cc
+++ b/server/modules/routing/cat/catsession.cc
@@ -72,7 +72,9 @@ void CatSession::clientReply(GWBUF* pPacket, DCB* pDcb)
     mxb_assert(backend->dcb() == pDcb);
     bool send = false;
 
-    if (backend->reply_is_complete(pPacket))
+    backend->process_reply(pPacket);
+
+    if (backend->reply_is_complete())
     {
         m_completed++;
         m_current++;
diff --git a/server/modules/routing/readwritesplit/rwsplitsession.cc b/server/modules/routing/readwritesplit/rwsplitsession.cc
index 25c38e138..2cf2aee72 100644
--- a/server/modules/routing/readwritesplit/rwsplitsession.cc
+++ b/server/modules/routing/readwritesplit/rwsplitsession.cc
@@ -560,7 +560,9 @@ void RWSplitSession::clientReply(GWBUF* writebuf, DCB* backend_dcb)
         m_current_query.reset();
     }
 
-    if (backend->reply_is_complete(writebuf))
+    backend->process_reply(writebuf);
+
+    if (backend->reply_is_complete())
     {
         /** Got a complete reply, decrement expected response count */
         m_expected_responses--;