Fixed problem with MySQL: it was possible for one thread to use an incomplete list of column names if another thread was creating the list at the same time. Now this is thread-safe.

3 files changed, 37 insertions, 21 deletions

diff --git a/OpenSim/Data/MySQL/MySQLAuthenticationData.cs b/OpenSim/Data/MySQL/MySQLAuthenticationData.cs
index 8d82f61..664ce84 100644
--- a/OpenSim/Data/MySQL/MySQLAuthenticationData.cs
+++ b/OpenSim/Data/MySQL/MySQLAuthenticationData.cs
@@ -79,14 +79,7 @@ namespace OpenSim.Data.MySQL
                 {
                     ret.PrincipalID = principalID;
 
-                    if (m_ColumnNames == null)
-                    {
-                        m_ColumnNames = new List<string>();
-
-                        DataTable schemaTable = result.GetSchemaTable();
-                        foreach (DataRow row in schemaTable.Rows)
-                            m_ColumnNames.Add(row["ColumnName"].ToString());
-                    }
+                    CheckColumnNames(result);
 
                     foreach (string s in m_ColumnNames)
                     {
@@ -105,6 +98,20 @@ namespace OpenSim.Data.MySQL
             }
         }
 
+        private void CheckColumnNames(IDataReader result)
+        {
+            if (m_ColumnNames != null)
+                return;
+
+            List<string> columnNames = new List<string>();
+
+            DataTable schemaTable = result.GetSchemaTable();
+            foreach (DataRow row in schemaTable.Rows)
+                columnNames.Add(row["ColumnName"].ToString());
+
+            m_ColumnNames = columnNames;
+        }
+
         public bool Store(AuthenticationData data)
         {
             if (data.Data.ContainsKey("UUID"))
diff --git a/OpenSim/Data/MySQL/MySQLGenericTableHandler.cs b/OpenSim/Data/MySQL/MySQLGenericTableHandler.cs
index 754cf72..da8e958 100644
--- a/OpenSim/Data/MySQL/MySQLGenericTableHandler.cs
+++ b/OpenSim/Data/MySQL/MySQLGenericTableHandler.cs
@@ -91,15 +91,17 @@ namespace OpenSim.Data.MySQL
             if (m_ColumnNames != null)
                 return;
 
-            m_ColumnNames = new List<string>();
+            List<string> columnNames = new List<string>();
 
             DataTable schemaTable = reader.GetSchemaTable();
             foreach (DataRow row in schemaTable.Rows)
             {
                 if (row["ColumnName"] != null &&
                         (!m_Fields.ContainsKey(row["ColumnName"].ToString())))
-                    m_ColumnNames.Add(row["ColumnName"].ToString());
+                    columnNames.Add(row["ColumnName"].ToString());
             }
+
+            m_ColumnNames = columnNames;
         }
 
         public virtual T[] Get(string field, string key)
diff --git a/OpenSim/Data/MySQL/MySQLRegionData.cs b/OpenSim/Data/MySQL/MySQLRegionData.cs
index 948cdf3..d1f1932 100644
--- a/OpenSim/Data/MySQL/MySQLRegionData.cs
+++ b/OpenSim/Data/MySQL/MySQLRegionData.cs
@@ -162,17 +162,7 @@ namespace OpenSim.Data.MySQL
                         ret.sizeX = Convert.ToInt32(result["sizeX"]);
                         ret.sizeY = Convert.ToInt32(result["sizeY"]);
 
-                        if (m_ColumnNames == null)
-                        {
-                            m_ColumnNames = new List<string>();
-
-                            DataTable schemaTable = result.GetSchemaTable();
-                            foreach (DataRow row in schemaTable.Rows)
-                            {
-                                if (row["ColumnName"] != null)
-                                    m_ColumnNames.Add(row["ColumnName"].ToString());
-                            }
-                        }
+                        CheckColumnNames(result);
 
                         foreach (string s in m_ColumnNames)
                         {
@@ -202,6 +192,23 @@ namespace OpenSim.Data.MySQL
             return retList;
         }
 
+        private void CheckColumnNames(IDataReader result)
+        {
+            if (m_ColumnNames != null)
+                return;
+
+            List<string> columnNames = new List<string>();
+
+            DataTable schemaTable = result.GetSchemaTable();
+            foreach (DataRow row in schemaTable.Rows)
+            {
+                if (row["ColumnName"] != null)
+                    columnNames.Add(row["ColumnName"].ToString());
+            }
+
+            m_ColumnNames = columnNames;
+        }
+
         public bool Store(RegionData data)
         {
             if (data.Data.ContainsKey("uuid"))