mcs/class/Npgsql/Npgsql/NpgsqlTransaction.cs

   1 // created on 17/11/2002 at 19:04
   2
   3 // Npgsql.NpgsqlTransaction.cs
   4 //
   5 // Author:
   6 //      Francisco Jr. (fxjrlists@yahoo.com.br)
   7 //
   8 //      Copyright (C) 2002 The Npgsql Development Team
   9 //      npgsql-general@gborg.postgresql.org
  10 //      http://gborg.postgresql.org/project/npgsql/projdisplay.php
  11 //
  12 // This library is free software; you can redistribute it and/or
  13 // modify it under the terms of the GNU Lesser General Public
  14 // License as published by the Free Software Foundation; either
  15 // version 2.1 of the License, or (at your option) any later version.
  16 //
  17 // This library is distributed in the hope that it will be useful,
  18 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20 // Lesser General Public License for more details.
  21 //
  22 // You should have received a copy of the GNU Lesser General Public
  23 // License along with this library; if not, write to the Free Software
  24 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  25
  26
  27 using System;
  28 using System.Text;
  29 using System.Resources;
  30 using System.Data;
  31
  32
  33 namespace Npgsql
  34 {
  35     /// <summary>
  36     /// Represents a transaction to be made in a PostgreSQL database. This class cannot be inherited.
  37     /// </summary>
  38     public sealed class NpgsqlTransaction : MarshalByRefObject, IDbTransaction
  39     {
  40         private static readonly String CLASSNAME = "NpgsqlTransaction";
  41         private static ResourceManager resman = new ResourceManager(typeof(NpgsqlTransaction));
  42
  43         private NpgsqlConnection    _conn = null;
  44         private IsolationLevel      _isolation = IsolationLevel.ReadCommitted;
  45         private bool                _disposed = false;
  46
  47         internal NpgsqlTransaction(NpgsqlConnection conn) : this(conn, IsolationLevel.ReadCommitted)
  48         {}
  49
  50         internal NpgsqlTransaction(NpgsqlConnection conn, IsolationLevel isolation)
  51         {
  52             resman = new System.Resources.ResourceManager(this.GetType());
  53
  54             NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, CLASSNAME);
  55             if ((isolation != IsolationLevel.ReadCommitted) &&
  56                     (isolation != IsolationLevel.Serializable))
  57                 throw new ArgumentOutOfRangeException(resman.GetString("Exception_UnsopportedIsolationLevel"), "isolation");
  58
  59             _conn = conn;
  60             _isolation = isolation;
  61
  62             StringBuilder commandText = new StringBuilder("SET TRANSACTION ISOLATION LEVEL ");
  63
  64             if (isolation == IsolationLevel.ReadCommitted)
  65                 commandText.Append("READ COMMITTED");
  66             else
  67                 commandText.Append("SERIALIZABLE");
  68
  69             commandText.Append("; BEGIN");
  70
  71             NpgsqlCommand command = new NpgsqlCommand(commandText.ToString(), conn.Connector);
  72             command.ExecuteNonQuery();
  73             _conn.Connector.Transaction = this;
  74         }
  75
  76         /// <summary>
  77         /// Gets the <see cref="Npgsql.NpgsqlConnection">NpgsqlConnection</see>
  78         /// object associated with the transaction, or a null reference if the
  79         /// transaction is no longer valid.
  80         /// </summary>
  81         /// <value>The <see cref="Npgsql.NpgsqlConnection">NpgsqlConnection</see>
  82         /// object associated with the transaction.</value>
  83         public NpgsqlConnection Connection
  84         {
  85             get
  86             {
  87                 return _conn;
  88             }
  89         }
  90
  91
  92         IDbConnection IDbTransaction.Connection
  93         {
  94             get
  95             {
  96                 return Connection;
  97             }
  98         }
  99
 100         /// <summary>
 101         /// Specifies the <see cref="System.Data.IsolationLevel">IsolationLevel</see> for this transaction.
 102         /// </summary>
 103         /// <value>The <see cref="System.Data.IsolationLevel">IsolationLevel</see> for this transaction.
 104         /// The default is <b>ReadCommitted</b>.</value>
 105         public IsolationLevel IsolationLevel
 106         {
 107             get
 108             {
 109                 if (_conn == null)
 110                 {
 111                     throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
 112                 }
 113
 114                 return _isolation;
 115             }
 116         }
 117
 118         /// <summary>
 119         /// Releases the unmanaged resources used by the
 120         /// <see cref="Npgsql.NpgsqlTransaction">NpgsqlTransaction</see>
 121         /// and optionally releases the managed resources.
 122         /// </summary>
 123         public void Dispose()
 124         {
 125             GC.SuppressFinalize(this);
 126
 127             this.Dispose(true);
 128         }
 129
 130         private void Dispose(Boolean disposing)
 131         {
 132             if(disposing && this._conn != null)
 133             {
 134                 if (_conn.Connector.Transaction != null)
 135                     this.Rollback();
 136
 137                 this._disposed = true;
 138             }
 139         }
 140
 141         /// <summary>
 142         /// Commits the database transaction.
 143         /// </summary>
 144         public void Commit()
 145         {
 146             CheckDisposed();
 147
 148             if (_conn == null)
 149             {
 150                 throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
 151             }
 152
 153             NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "Commit");
 154
 155             NpgsqlCommand command = new NpgsqlCommand("COMMIT", _conn.Connector);
 156             command.ExecuteNonQuery();
 157             _conn.Connector.Transaction = null;
 158             _conn = null;
 159         }
 160
 161         /// <summary>
 162         /// Rolls back a transaction from a pending state.
 163         /// </summary>
 164         public void Rollback()
 165         {
 166             CheckDisposed();
 167
 168             if (_conn == null)
 169             {
 170                 throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
 171             }
 172
 173             NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "Rollback");
 174
 175             NpgsqlCommand command = new NpgsqlCommand("ROLLBACK", _conn.Connector);
 176             command.ExecuteNonQuery();
 177             _conn.Connector.Transaction = null;
 178             _conn = null;
 179         }
 180
 181         /// <summary>
 182         /// Cancel the transaction without telling the backend about it.  This is
 183         /// used to make the transaction go away when closing a connection.
 184         /// </summary>
 185         internal void Cancel()
 186         {
 187             CheckDisposed();
 188
 189             if (_conn != null)
 190             {
 191                 _conn.Connector.Transaction = null;
 192                 _conn = null;
 193             }
 194         }
 195
 196         internal bool Disposed{
 197             get
 198             {
 199                 return _disposed;
 200             }
 201         }
 202
 203
 204         internal void CheckDisposed()
 205         {
 206             if (_disposed)
 207                 throw new ObjectDisposedException(CLASSNAME);
 208
 209         }
 210
 211         ~NpgsqlTransaction()
 212         {
 213             Dispose(false);
 214         }
 215
 216     }
 217 }