Erster Versuch, eine ASYNC Version des DBManagers zu starten

bsmd.database/DBManager.cs

@@ -15,6 +15,8 @@ using System.Diagnostics;
 using Newtonsoft.Json;
 using log4net;
 using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using System.Threading;
 
 namespace bsmd.database
 {
@@ -32,6 +34,7 @@ namespace bsmd.database
         private bool _closeConnectionAfterUse = false;
         private readonly List<string> truncatedFieldCollection = new List<string>();
         private Dictionary<Type, string> messageHistoryTypeDict;
+        private SemaphoreSlim _asyncSemaphore = new SemaphoreSlim(1);
 
         #endregion
 
@@ -99,6 +102,22 @@ namespace bsmd.database
             }
         }
 
+        public async Task<bool> ConnectAsync(string dbConnectionString)
+        {
+            try
+            {
+                _con = new SqlConnection(dbConnectionString);
+                await _con.OpenAsync();
+                this.ConnectionString = dbConnectionString;
+                return true;
+            }
+            catch(Exception ex)
+            {
+                _log.ErrorFormat("DBManager cannot connect:{0}", ex.Message);
+                return false;
+            }
+        }
+
         public void Disconnect()
         {
             if (this._con?.State == ConnectionState.Open)
@@ -785,6 +804,13 @@ namespace bsmd.database
                 this.Connect(this.ConnectionString);
         }
 
+        private async Task CheckConnectionAsync()
+        {
+            if ((this._con == null) ||
+                (this._con.State == ConnectionState.Closed))
+                await this.ConnectAsync(this.ConnectionString);
+        }
+
         private void LogNonQueryResult(string query, int queryResult)
         {
             switch (queryResult)
@@ -1537,7 +1563,7 @@ namespace bsmd.database
                     cmd.Connection = this._con;
                     // Stopwatch sw = new Stopwatch();
                     // sw.Start();
-                    reader = cmd.ExecuteReader();                    
+                    reader = cmd.ExecuteReader();
                     // sw.Stop();
                     // _log.DebugFormat("{1}ms:  {0}", cmd.CommandText, sw.ElapsedMilliseconds);
                     
@@ -1660,7 +1686,41 @@ namespace bsmd.database
                     bulkCopy.WriteToServer(table);
                 }
             }
-        }        
+        }
+
+        #endregion
+
+        #region async DB access methods
+
+        internal async Task<SqlDataReader> PerformCommandAsync(SqlCommand cmd)
+        {
+            SqlDataReader reader = null;
+
+            await _asyncSemaphore.WaitAsync();
+            try
+            {
+                await this.CheckConnectionAsync();
+                cmd.Connection = this._con;
+                reader = await cmd.ExecuteReaderAsync();
+            }
+            catch (SqlException ex)
+            {
+                Trace.WriteLine("SQL Exception:" + ex.Message);
+                _log.Error("Error performing command", ex);
+                _log.DebugFormat("Query: {0}", cmd.CommandText);
+                _log.Debug("Parameters:");
+                for (int i = 0; i < cmd.Parameters.Count; i++)
+                {
+                    _log.DebugFormat("{0}:{1}", cmd.Parameters[i].ParameterName, cmd.Parameters[i].Value);
+                }
+            }
+            finally
+            {
+                _asyncSemaphore.Release();
+            }
+
+            return reader;
+        }
 
         #endregion