From 27977b913da3321653e7d6cdc34d9f1c97609b74 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlos=20Mart=C3=ADn?= <cmartins@fdi.ucm.es>
Date: Fri, 6 May 2011 17:06:57 +0200
Subject: [PATCH] Bug #408: reconnect to MySQL server when connection fails

---
 include/MySqlDB.h    | 23 ++++++++++++++++++-----
 src/nebula/Nebula.cc | 10 +---------
 src/sql/MySqlDB.cc   | 41 +++++++++++++++++++++++++++++++++--------
 3 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/include/MySqlDB.h b/include/MySqlDB.h
index b733020de2..24fc5844db 100644
--- a/include/MySqlDB.h
+++ b/include/MySqlDB.h
@@ -43,11 +43,11 @@ class MySqlDB : public SqlDB
 {
 public:
 
-    MySqlDB(const string& server,
-            int           port,
-            const string& user,
-            const string& password,
-            const char *  database);
+    MySqlDB(const string& _server,
+            int           _port,
+            const string& _user,
+            const string& _password,
+            const string& _database);
 
     ~MySqlDB();
 
@@ -81,6 +81,19 @@ private:
      */
     MYSQL *             db;
 
+    /**
+     *  MySQL Connection parameters
+     */
+    string              server;
+
+    int                 port;
+
+    string              user;
+
+    string              password;
+
+    string              database;
+
     /**
      *  Fine-grain mutex for DB access
      */
diff --git a/src/nebula/Nebula.cc b/src/nebula/Nebula.cc
index a3cd371947..786370364e 100644
--- a/src/nebula/Nebula.cc
+++ b/src/nebula/Nebula.cc
@@ -208,7 +208,7 @@ void Nebula::start()
         {
             ostringstream   oss;
 
-            db = new MySqlDB(server,port,user,passwd,0);
+            db = new MySqlDB(server,port,user,passwd,db_name);
 
             oss << "CREATE DATABASE IF NOT EXISTS " << db_name;
             rc = db->exec(oss);
@@ -217,14 +217,6 @@ void Nebula::start()
             {
                 throw runtime_error("Could not create database.");
             }
-
-            oss.str("");
-            oss << "USE " << db_name;
-            rc = db->exec(oss);
-            if ( rc != 0 )
-            {
-                throw runtime_error("Could not open database.");
-            }
         }
 
         NebulaLog::log("ONE",Log::INFO,"Bootstraping OpenNebula database.");
diff --git a/src/sql/MySqlDB.cc b/src/sql/MySqlDB.cc
index 0a8895d5b6..1e9cebd815 100644
--- a/src/sql/MySqlDB.cc
+++ b/src/sql/MySqlDB.cc
@@ -15,6 +15,7 @@
 /* -------------------------------------------------------------------------- */
 
 #include "MySqlDB.h"
+#include <mysql/errmsg.h>
 
 /*********
  * Doc: http://dev.mysql.com/doc/refman/5.5/en/c-api-function-overview.html
@@ -23,12 +24,17 @@
 /* -------------------------------------------------------------------------- */
 
 MySqlDB::MySqlDB(
-        const string& server,
-        int           port,
-        const string& user,
-        const string& password,
-        const char *  database)
+        const string& _server,
+        int           _port,
+        const string& _user,
+        const string& _password,
+        const string& _database)
 {
+    server   = _server;
+    port     = _port;
+    user     = _user;
+    password = _password;
+    database = _database;
 
     // Initialize the MySQL library
     mysql_library_init(0, NULL, NULL);
@@ -38,7 +44,7 @@ MySqlDB::MySqlDB(
 
     // Connect to the server
     if (!mysql_real_connect(db, server.c_str(), user.c_str(),
-                            password.c_str(), database, port, NULL, 0))
+                            password.c_str(), database.c_str(), port, NULL, 0))
     {
         throw runtime_error("Could not open database.");
     }
@@ -81,8 +87,27 @@ int MySqlDB::exec(ostringstream& cmd, Callbackable* obj)
         const char *    err_msg = mysql_error(db);
         int             err_num = mysql_errno(db);
 
-        oss << "SQL command was: " << c_str;
-        oss << ", error " << err_num << " : " << err_msg;
+        if( err_num == CR_SERVER_GONE_ERROR || err_num == CR_SERVER_LOST )
+        {
+            oss << "MySQL connection error " << err_num << " : " << err_msg;
+
+            // Try to re-connect
+            if (mysql_real_connect(db, server.c_str(), user.c_str(),
+                                    password.c_str(), database.c_str(),
+                                    port, NULL, 0))
+            {
+                oss << "... Reconnected.";
+            }
+            else
+            {
+                oss << "... Reconnection attempt failed.";
+            }
+        }
+        else
+        {
+            oss << "SQL command was: " << c_str;
+            oss << ", error " << err_num << " : " << err_msg;
+        }
 
         NebulaLog::log("ONE",Log::ERROR,oss);