// created on 17/11/2002 at 19:04
// Npgsql.NpgsqlTransaction.cs
//
// Author:
// Francisco Jr. (fxjrlists@yahoo.com.br)
//
// Copyright (C) 2002 The Npgsql Development Team
// npgsql-general@gborg.postgresql.org
// http://gborg.postgresql.org/project/npgsql/projdisplay.php
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
using System;
using System.Text;
using System.Resources;
using System.Data;
namespace Npgsql
{
///
/// Represents a transaction to be made in a PostgreSQL database. This class cannot be inherited.
///
public sealed class NpgsqlTransaction : MarshalByRefObject, IDbTransaction
{
private static readonly String CLASSNAME = "NpgsqlTransaction";
private static ResourceManager resman = new ResourceManager(typeof(NpgsqlTransaction));
private NpgsqlConnection _conn = null;
private IsolationLevel _isolation = IsolationLevel.ReadCommitted;
private bool _disposed = false;
internal NpgsqlTransaction(NpgsqlConnection conn) : this(conn, IsolationLevel.ReadCommitted)
{}
internal NpgsqlTransaction(NpgsqlConnection conn, IsolationLevel isolation)
{
resman = new System.Resources.ResourceManager(this.GetType());
NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, CLASSNAME);
if ((isolation != IsolationLevel.ReadCommitted) &&
(isolation != IsolationLevel.Serializable))
throw new ArgumentOutOfRangeException(resman.GetString("Exception_UnsopportedIsolationLevel"), "isolation");
_conn = conn;
_isolation = isolation;
StringBuilder commandText = new StringBuilder("SET TRANSACTION ISOLATION LEVEL ");
if (isolation == IsolationLevel.ReadCommitted)
commandText.Append("READ COMMITTED");
else
commandText.Append("SERIALIZABLE");
commandText.Append("; BEGIN");
NpgsqlCommand command = new NpgsqlCommand(commandText.ToString(), conn.Connector);
command.ExecuteNonQuery();
_conn.Connector.Transaction = this;
}
///
/// Gets the NpgsqlConnection
/// object associated with the transaction, or a null reference if the
/// transaction is no longer valid.
///
/// The NpgsqlConnection
/// object associated with the transaction.
public NpgsqlConnection Connection
{
get
{
return _conn;
}
}
IDbConnection IDbTransaction.Connection
{
get
{
return Connection;
}
}
///
/// Specifies the IsolationLevel for this transaction.
///
/// The IsolationLevel for this transaction.
/// The default is ReadCommitted.
public IsolationLevel IsolationLevel
{
get
{
if (_conn == null)
{
throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
}
return _isolation;
}
}
///
/// Releases the unmanaged resources used by the
/// NpgsqlTransaction
/// and optionally releases the managed resources.
///
public void Dispose()
{
GC.SuppressFinalize(this);
this.Dispose(true);
}
private void Dispose(Boolean disposing)
{
if(disposing && this._conn != null)
{
if (_conn.Connector.Transaction != null)
this.Rollback();
this._disposed = true;
}
}
///
/// Commits the database transaction.
///
public void Commit()
{
CheckDisposed();
if (_conn == null)
{
throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
}
NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "Commit");
NpgsqlCommand command = new NpgsqlCommand("COMMIT", _conn.Connector);
command.ExecuteNonQuery();
_conn.Connector.Transaction = null;
_conn = null;
}
///
/// Rolls back a transaction from a pending state.
///
public void Rollback()
{
CheckDisposed();
if (_conn == null)
{
throw new InvalidOperationException(resman.GetString("Exception_NoTransaction"));
}
NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "Rollback");
NpgsqlCommand command = new NpgsqlCommand("ROLLBACK", _conn.Connector);
command.ExecuteNonQuery();
_conn.Connector.Transaction = null;
_conn = null;
}
///
/// Cancel the transaction without telling the backend about it. This is
/// used to make the transaction go away when closing a connection.
///
internal void Cancel()
{
CheckDisposed();
if (_conn != null)
{
_conn.Connector.Transaction = null;
_conn = null;
}
}
internal bool Disposed{
get
{
return _disposed;
}
}
internal void CheckDisposed()
{
if (_disposed)
throw new ObjectDisposedException(CLASSNAME);
}
~NpgsqlTransaction()
{
Dispose(false);
}
}
}