// 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

//

// Permission to use, copy, modify, and distribute this software and its

// documentation for any purpose, without fee, and without a written

// agreement is hereby granted, provided that the above copyright notice

// and this paragraph and the following two paragraphs appear in all copies.

//

// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY

// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,

// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS

// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF

// THE POSSIBILITY OF SUCH DAMAGE.

//

// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,

// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY

// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS

// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS

// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

using System;

using System.Data;

using System.Data.Common;

using System.Diagnostics.Contracts;

using Npgsql.FrontendMessages;

using Npgsql.Logging;

namespace Npgsql

{

/// <summary>

/// Represents a transaction to be made in a PostgreSQL database. This class cannot be inherited.

/// </summary>

public sealed class NpgsqlTransaction : DbTransaction

{

#region Fields and Properties

/// <summary>

/// Specifies the <see cref="NpgsqlConnection"/> object associated with the transaction.

/// </summary>

/// <value>The <see cref="NpgsqlConnection"/> object associated with the transaction.</value>

public new NpgsqlConnection Connection { get; internal set; }

/// <summary>

/// Specifies the <see cref="NpgsqlConnection"/> object associated with the transaction.

/// </summary>

/// <value>The <see cref="NpgsqlConnection"/> object associated with the transaction.</value>

protected override DbConnection DbConnection { get { return Connection; } }

NpgsqlConnector Connector { get { return Connection.Connector; } }

bool _isDisposed;

/// <summary>

/// Specifies the <see cref="System.Data.IsolationLevel">IsolationLevel</see> for this transaction.

/// </summary>

/// <value>The <see cref="System.Data.IsolationLevel">IsolationLevel</see> for this transaction.

/// The default is <b>ReadCommitted</b>.</value>

public override IsolationLevel IsolationLevel

{

get

{

CheckReady();

return _isolationLevel;

}

}

readonly IsolationLevel _isolationLevel;

static readonly NpgsqlLogger Log = NpgsqlLogManager.GetCurrentClassLogger();

#endregion

#region Constructors

internal NpgsqlTransaction(NpgsqlConnection conn)

: this(conn, IsolationLevel.ReadCommitted)

{

Contract.Requires(conn != null);

}

internal NpgsqlTransaction(NpgsqlConnection conn, IsolationLevel isolationLevel)

{

Contract.Requires(conn != null);

Connection = conn;

_isolationLevel = isolationLevel;

Connector.Transaction = this;

Connector.TransactionStatus = TransactionStatus.Pending;

switch (isolationLevel) {

case IsolationLevel.RepeatableRead:

Connector.PrependMessage(PregeneratedMessage.BeginTransRepeatableRead);

break;

case IsolationLevel.Serializable:

case IsolationLevel.Snapshot:

Connector.PrependMessage(PregeneratedMessage.BeginTransSerializable);

break;

case IsolationLevel.ReadUncommitted:

// PG doesn't really support ReadUncommitted, it's the same as ReadCommitted. But we still

// send as if.

Connector.PrependMessage(PregeneratedMessage.BeginTransReadUncommitted);

break;

case IsolationLevel.ReadCommitted:

Connector.PrependMessage(PregeneratedMessage.BeginTransReadCommitted);

break;

default:

throw new NotSupportedException("Isolation level not supported: " + isolationLevel);

}

}

#endregion

#region Commit and Rollback

/// <summary>

/// Commits the database transaction.

/// </summary>

public override void Commit()

{

CheckReady();

Log.Debug("Commit transaction", Connection.Connector.Id);

Connection.Connector.ExecuteBlind(PregeneratedMessage.CommitTransaction);

Connection = null;

}

/// <summary>

/// Rolls back a transaction from a pending state.

/// </summary>

public override void Rollback()

{

CheckReady();

Log.Debug("Rollback transaction", Connection.Connector.Id);

Connection.Connector.ExecuteBlindSuppressTimeout(PregeneratedMessage.RollbackTransaction);

Connection = null;

}

#endregion

#region Savepoints

/// <summary>

/// Rolls back a transaction from a pending savepoint state.

/// </summary>

public void Rollback(string savePointName)

{

CheckReady();

if (!Connection.Connector.SupportsSavepoint)

{

throw new InvalidOperationException("Savepoint is not supported by backend.");

}

if (savePointName.Contains(";"))

{

throw new InvalidOperationException("Savepoint name cannot have semicolon.");

}

Connection.Connector.ExecuteBlindSuppressTimeout(string.Format("ROLLBACK TO SAVEPOINT {0}", savePointName));

}

/// <summary>

/// Creates a transaction save point.

/// </summary>

public void Save(String savePointName)

{

CheckReady();

if (!Connection.Connector.SupportsSavepoint)

{

throw new InvalidOperationException("Savepoint is not supported by backend.");

}

if (savePointName.Contains(";"))

{

throw new InvalidOperationException("Savepoint name cannot have semicolon.");

}

Connection.Connector.ExecuteBlind(string.Format("SAVEPOINT {0}", savePointName));

}

#endregion

#region Dispose

/// <summary>

/// Dispose.

/// </summary>

/// <param name="disposing"></param>

protected override void Dispose(bool disposing)

{

if (_isDisposed) { return; }

if (disposing && Connection != null) {

Rollback();

}

_isDisposed = true;

base.Dispose(disposing);

}

#endregion

#region Checks

void CheckReady()

{

CheckDisposed();

CheckCompleted();

Connection.CheckConnectionReady();

}

[ContractArgumentValidator]

void CheckCompleted()

{

if (Connection == null)

throw new InvalidOperationException("This NpgsqlTransaction has completed; it is no longer usable.");

Contract.EndContractBlock();

}

[ContractArgumentValidator]

void CheckDisposed()

{

if (_isDisposed)

throw new ObjectDisposedException(typeof(NpgsqlTransaction).Name);

Contract.EndContractBlock();

}

[ContractInvariantMethod]

void ObjectInvariants()

{

}

#endregion

}

}