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                _disposing = 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                     throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
 111                 }
 112
 113                 return _isolation;
 114             }
 115         }
 116
 117         /// <summary>
 118         /// Releases the unmanaged resources used by the
 119         /// <see cref="Npgsql.NpgsqlTransaction">NpgsqlTransaction</see>
 120         /// and optionally releases the managed resources.
 121         /// </summary>
 122         public void Dispose()
 123         {
 124             this.Dispose(true);
 125         }
 126
 127         private void Dispose(bool disposing)
 128         {
 129             if(disposing && this._conn != null)
 130             {
 131                 this._disposing = true;
 132                 if (_conn.Connector.Transaction != null)
 133                     this.Rollback();
 134             }
 135         }
 136
 137         /// <summary>
 138         /// Commits the database transaction.
 139         /// </summary>
 140         public void Commit()
 141         {
 142             if (_conn == null) {
 143                 throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
 144             }
 145
 146             NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "Commit");
 147
 148             NpgsqlCommand command = new NpgsqlCommand("COMMIT", _conn.Connector);
 149             command.ExecuteNonQuery();
 150             _conn.Connector.Transaction = null;
 151             _conn = null;
 152         }
 153
 154         /// <summary>
 155         /// Rolls back a transaction from a pending state.
 156         /// </summary>
 157         public void Rollback()
 158         {
 159             if (_conn == null) {
 160                 throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
 161             }
 162
 163             NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "Rollback");
 164
 165             NpgsqlCommand command = new NpgsqlCommand("ROLLBACK", _conn.Connector);
 166             command.ExecuteNonQuery();
 167             _conn.Connector.Transaction = null;
 168             _conn = null;
 169         }
 170
 171         /// <summary>
 172         /// Cancel the transaction without telling the backend about it.  This is
 173         /// used to make the transaction go away when closing a connection.
 174         /// </summary>
 175         internal void Cancel()
 176         {
 177             if (_conn != null) {
 178                 _conn.Connector.Transaction = null;
 179                 _conn = null;
 180             }
 181         }
 182
 183         internal bool Disposing{
 184             get
 185             {
 186                 return _disposing;
 187             }
 188         }
 189     }
 190 }