From 8721c9117ad3abc5fb6793f7cf12c8b314cff9a8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20M=C3=A4kel=C3=A4?= <markus.makela@mariadb.com>
Date: Mon, 11 Jun 2018 09:31:18 +0300
Subject: [PATCH] Expose function for checking MYSQL connection errors

If a query done via the connector fails, the return value can be inspected
with the function. This helps separate fatal problems from transient ones.
---
 include/maxscale/mysql_utils.h | 7 +++++++
 server/core/mysql_utils.cc     | 4 ++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/maxscale/mysql_utils.h b/include/maxscale/mysql_utils.h
index 7bb1f68b5..8c1f50a16 100644
--- a/include/maxscale/mysql_utils.h
+++ b/include/maxscale/mysql_utils.h
@@ -41,6 +41,13 @@ char* mxs_lestr_consume(uint8_t** c, size_t *size);
  */
 MYSQL* mxs_mysql_real_connect(MYSQL *mysql, SERVER *server, const char *user, const char *passwd);
 
+/**
+ * Check if the MYSQL error number is a connection error
+ *
+ * @return True if the MYSQL error number is a connection error
+ */
+bool mxs_mysql_is_net_error(int errcode);
+
 /**
  * Execute a query
  *
diff --git a/server/core/mysql_utils.cc b/server/core/mysql_utils.cc
index f09e5ed89..2218fe5bc 100644
--- a/server/core/mysql_utils.cc
+++ b/server/core/mysql_utils.cc
@@ -217,7 +217,7 @@ MYSQL *mxs_mysql_real_connect(MYSQL *con, SERVER *server, const char *user, cons
     return mysql;
 }
 
-static bool is_connection_error(int errcode)
+bool mxs_mysql_is_net_error(int errcode)
 {
     switch (errcode)
     {
@@ -242,7 +242,7 @@ int mxs_mysql_query(MYSQL* conn, const char* query)
     int rc = mysql_query(conn, query);
 
     for (int n = 0; rc != 0 && n < cnf->query_retries &&
-         is_connection_error(mysql_errno(conn)) &&
+         mxs_mysql_is_net_error(mysql_errno(conn)) &&
          time(NULL) - start < cnf->query_retry_timeout; n++)
     {
         rc = mysql_query(conn, query);