From e1b611aa06af420c32ecc0b3659100bc328079cf Mon Sep 17 00:00:00 2001
From: Johan Wikman <johan.wikman@mariadb.com>
Date: Thu, 6 Jun 2019 12:16:18 +0300
Subject: [PATCH] MXS-2512 Use existing information

As an error returned by the server is now stored inside RWBackend,
irrespective of whether it is returned solely or e.g. last after
a result set, there is no need to examine the GWBUF in rws, but
we can use the information that exists.
---
 .../routing/readwritesplit/rwsplitsession.cc  | 66 ++-----------------
 1 file changed, 5 insertions(+), 61 deletions(-)

diff --git a/server/modules/routing/readwritesplit/rwsplitsession.cc b/server/modules/routing/readwritesplit/rwsplitsession.cc
index 4c6a46ea5..50a12f18e 100644
--- a/server/modules/routing/readwritesplit/rwsplitsession.cc
+++ b/server/modules/routing/readwritesplit/rwsplitsession.cc
@@ -575,66 +575,6 @@ void RWSplitSession::close_stale_connections()
     }
 }
 
-namespace
-{
-
-inline bool is_transaction_rollback(uint8_t* pData)
-{
-    bool rv = false;
-
-    // The 'sql_state' of all transaction rollbacks is "40XXX". In an error
-    // packet, the 'sql_state' is found in the payload at offset 4, after the one
-    // byte 'header', the two byte 'error_code', and the 1 byte 'sql_state_marker'.
-    uint8_t* p = pData + MYSQL_HEADER_LEN + 1 + 2 + 1;
-
-    if (*p++ == '4' && *p == '0')
-    {
-        rv = true;
-
-        if (mxb_log_is_priority_enabled(LOG_INFO))
-        {
-            // p now points at the second byte of the 5 byte long 'sql_state'.
-            p += 4;     // Now at the start of the human readable error message
-
-            uint8_t* end = pData + MYSQL_HEADER_LEN + MYSQL_GET_PAYLOAD_LEN(pData);
-            int len = end - p;
-            char message[len + 1];
-            memcpy(message, p, len);
-            message[len] = 0;
-
-            MXS_NOTICE("A retryable Clustrix error: %s", message);
-        }
-    }
-
-    return rv;
-}
-
-bool is_transaction_rollback(GWBUF* writebuf)
-{
-    bool rv = false;
-
-    if (MYSQL_IS_ERROR_PACKET(GWBUF_DATA(writebuf)))
-    {
-        if (GWBUF_IS_CONTIGUOUS(writebuf))
-        {
-            rv = is_transaction_rollback(GWBUF_DATA(writebuf));
-        }
-        else
-        {
-            uint8_t* pData = GWBUF_DATA(writebuf);
-            int len = MYSQL_HEADER_LEN + MYSQL_GET_PAYLOAD_LEN(pData);
-            uint8_t data[len];
-
-            gwbuf_copy_data(writebuf, 0, len, data);
-
-            rv = is_transaction_rollback(data);
-        }
-    }
-
-    return rv;
-}
-}
-
 void RWSplitSession::clientReply(GWBUF* writebuf, DCB* backend_dcb)
 {
     DCB* client_dcb = backend_dcb->session->client_dcb;
@@ -673,8 +613,12 @@ void RWSplitSession::clientReply(GWBUF* writebuf, DCB* backend_dcb)
 
     backend->process_reply(writebuf);
 
-    if (m_config.transaction_replay && is_transaction_rollback(writebuf))
+    const RWBackend::Error& error = backend->error();
+
+    if (error && m_config.transaction_replay && error.is_rollback())
     {
+        MXS_INFO("A retryable error: %s", error.message().c_str());
+
         // writebuf was an error that can be handled by replaying the transaction.
         m_expected_responses--;