class/Npgsql/Npgsql/NpgsqlTransactionCallbacks.cs

   1 // NpgsqlTransactionCallbacks.cs
   2 //
   3 // Author:
   4 //  Josh Cooley <jbnpgsql@tuxinthebox.net>
   5 //
   6 // Copyright (C) 2007, The Npgsql Development Team
   7 //
   8 // Permission to use, copy, modify, and distribute this software and its
   9 // documentation for any purpose, without fee, and without a written
  10 // agreement is hereby granted, provided that the above copyright notice
  11 // and this paragraph and the following two paragraphs appear in all copies.
  12 //
  13 // IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
  14 // FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
  15 // INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
  16 // DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
  17 // THE POSSIBILITY OF SUCH DAMAGE.
  18 //
  19 // THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
  20 // INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  21 // AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
  22 // ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
  23 // TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  24
  25 using System;
  26 using System.Data;
  27
  28 namespace Npgsql
  29 {
  30         internal interface INpgsqlTransactionCallbacks : IDisposable
  31         {
  32                 string GetName();
  33                 void PrepareTransaction();
  34                 void CommitTransaction();
  35                 void RollbackTransaction();
  36         }
  37
  38         internal class NpgsqlTransactionCallbacks : MarshalByRefObject, INpgsqlTransactionCallbacks
  39         {
  40                 private NpgsqlConnection _connection;
  41                 private readonly string _connectionString;
  42                 private bool _closeConnectionRequired;
  43                 private bool _prepared;
  44                 private readonly string _txName = Guid.NewGuid().ToString();
  45
  46                 private static readonly String CLASSNAME = "NpgsqlTransactionCallbacks";
  47
  48                 public NpgsqlTransactionCallbacks(NpgsqlConnection connection)
  49                 {
  50                         _connection = connection;
  51                         _connectionString = _connection.ConnectionString;
  52                         _connection.Disposed += new EventHandler(_connection_Disposed);
  53                 }
  54
  55                 private void _connection_Disposed(object sender, EventArgs e)
  56                 {
  57                         // TODO: what happens if this is called from another thread?
  58                         // connections should not be shared across threads while in a transaction
  59                         _connection.Disposed -= new EventHandler(_connection_Disposed);
  60                         _connection = null;
  61                 }
  62
  63                 private NpgsqlConnection GetConnection()
  64                 {
  65                         if (_connection == null || (_connection.FullState & ConnectionState.Open) != ConnectionState.Open)
  66                         {
  67                                 _connection = new NpgsqlConnection(_connectionString);
  68                                 _connection.Open();
  69                                 _closeConnectionRequired = true;
  70                                 return _connection;
  71                         }
  72                         else
  73                         {
  74                                 return _connection;
  75                         }
  76                 }
  77
  78                 #region INpgsqlTransactionCallbacks Members
  79
  80                 public string GetName()
  81                 {
  82                         return _txName;
  83                 }
  84
  85                 public void CommitTransaction()
  86                 {
  87                         NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "CommitTransaction");
  88                         NpgsqlConnection connection = GetConnection();
  89                         NpgsqlCommand command = null;
  90                         if (_prepared)
  91                         {
  92                                 command = new NpgsqlCommand(string.Format("COMMIT PREPARED '{0}'", _txName), connection);
  93                         }
  94                         else
  95                         {
  96                                 command = new NpgsqlCommand("COMMIT", connection);
  97                         }
  98                         command.ExecuteBlind();
  99                 }
 100
 101                 public void PrepareTransaction()
 102                 {
 103             if (!_prepared)
 104             {
 105                 NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "PrepareTransaction");
 106                 NpgsqlConnection connection = GetConnection();
 107                 NpgsqlCommand command = new NpgsqlCommand(string.Format("PREPARE TRANSACTION '{0}'", _txName), connection);
 108                 command.ExecuteBlind();
 109                 _prepared = true;
 110             }
 111                 }
 112
 113                 public void RollbackTransaction()
 114                 {
 115                         NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "RollbackTransaction");
 116                         NpgsqlConnection connection = GetConnection();
 117                         NpgsqlCommand command = null;
 118                         if (_prepared)
 119                         {
 120                                 command = new NpgsqlCommand(string.Format("ROLLBACK PREPARED '{0}'", _txName), connection);
 121                         }
 122                         else
 123                         {
 124                                 command = new NpgsqlCommand("ROLLBACK", connection);
 125                         }
 126                         command.ExecuteBlind();
 127                 }
 128
 129                 #endregion
 130
 131                 #region IDisposable Members
 132
 133                 public void Dispose()
 134                 {
 135                         if (_closeConnectionRequired)
 136                         {
 137                                 _connection.Close();
 138                         }
 139                         _closeConnectionRequired = false;
 140                 }
 141
 142                 #endregion
 143         }
 144 }