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NpgsqlTransaction.cs
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312 lines (261 loc) · 10.6 KB
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#region License
// The PostgreSQL License
//
// Copyright (C) 2015 The Npgsql Development Team
//
// 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.
#endregion
using System;
using System.Data;
using System.Data.Common;
using System.Diagnostics.Contracts;
using Npgsql.BackendMessages;
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;
const IsolationLevel DefaultIsolationLevel = IsolationLevel.ReadCommitted;
static readonly NpgsqlLogger Log = NpgsqlLogManager.GetCurrentClassLogger();
#endregion
#region Constructors
internal NpgsqlTransaction(NpgsqlConnection conn)
: this(conn, DefaultIsolationLevel)
{
Contract.Requires(conn != null);
}
internal NpgsqlTransaction(NpgsqlConnection conn, IsolationLevel isolationLevel)
{
Contract.Requires(conn != null);
Contract.Requires(isolationLevel != IsolationLevel.Chaos);
Connection = conn;
Connector.Transaction = this;
Connector.TransactionStatus = TransactionStatus.Pending;
switch (isolationLevel) {
case IsolationLevel.RepeatableRead:
Connector.PrependInternalMessage(PregeneratedMessage.BeginTransRepeatableRead);
break;
case IsolationLevel.Serializable:
case IsolationLevel.Snapshot:
Connector.PrependInternalMessage(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.PrependInternalMessage(PregeneratedMessage.BeginTransReadUncommitted);
break;
case IsolationLevel.ReadCommitted:
Connector.PrependInternalMessage(PregeneratedMessage.BeginTransReadCommitted);
break;
case IsolationLevel.Unspecified:
isolationLevel = DefaultIsolationLevel;
goto case DefaultIsolationLevel;
default:
throw PGUtil.ThrowIfReached("Isolation level not supported: " + isolationLevel);
}
_isolationLevel = isolationLevel;
}
#endregion
#region Commit and Rollback
/// <summary>
/// Commits the database transaction.
/// </summary>
public override void Commit()
{
CheckReady();
Log.Debug("Commit transaction", Connection.Connector.Id);
Connector.ExecuteInternalCommand(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);
var connector = Connector;
try
{
// If we're in a failed transaction we can't set the timeout
var withTimeout = connector.TransactionStatus != TransactionStatus.InFailedTransactionBlock;
connector.ExecuteInternalCommand(PregeneratedMessage.RollbackTransaction, withTimeout);
}
finally
{
// The rollback may change the value of statement_value, set to unknown
connector.SetBackendTimeoutToUnknown();
}
Connection = null;
}
#endregion
#region Savepoints
/// <summary>
/// Creates a transaction save point.
/// </summary>
public void Save(string name)
{
if (name == null)
throw new ArgumentNullException("name");
if (string.IsNullOrWhiteSpace(name))
throw new ArgumentException("name can't be empty", "name");
if (name.Contains(";"))
throw new ArgumentException("name can't contain a semicolon");
Contract.EndContractBlock();
CheckReady();
Log.Debug("Create savepoint", Connection.Connector.Id);
Connector.ExecuteInternalCommand(new QueryMessage(string.Format("SAVEPOINT {0}", name)));
}
/// <summary>
/// Rolls back a transaction from a pending savepoint state.
/// </summary>
public void Rollback(string name)
{
if (name == null)
throw new ArgumentNullException("name");
if (string.IsNullOrWhiteSpace(name))
throw new ArgumentException("name can't be empty", "name");
if (name.Contains(";"))
throw new ArgumentException("name can't contain a semicolon");
Contract.EndContractBlock();
CheckReady();
Log.Debug("Rollback savepoint", Connection.Connector.Id);
try {
// If we're in a failed transaction we can't set the timeout
var withTimeout = Connector.TransactionStatus != TransactionStatus.InFailedTransactionBlock;
Connector.ExecuteInternalCommand(new QueryMessage(string.Format("ROLLBACK TO SAVEPOINT {0}", name)), withTimeout);
} finally {
// The rollback may change the value of statement_value, set to unknown
Connection.Connector.SetBackendTimeoutToUnknown();
}
}
/// <summary>
/// Rolls back a transaction from a pending savepoint state.
/// </summary>
public void Release(string name)
{
if (name == null)
throw new ArgumentNullException("name");
if (string.IsNullOrWhiteSpace(name))
throw new ArgumentException("name can't be empty", "name");
if (name.Contains(";"))
throw new ArgumentException("name can't contain a semicolon");
Contract.EndContractBlock();
CheckReady();
Log.Debug("Release savepoint", Connection.Connector.Id);
Connector.ExecuteInternalCommand(new QueryMessage(string.Format("RELEASE SAVEPOINT {0}", name)));
}
/// <summary>
/// Creates a transaction save point.
/// </summary>
[Obsolete("Use Save instead")]
public void CreateSavepoint(string name)
{
Save(name);
}
/// <summary>
/// Rolls back a transaction from a pending savepoint state.
/// </summary>
[Obsolete("Use Rollback instead")]
public void RollbackToSavepoint(string name)
{
Rollback(name);
}
/// <summary>
/// Rolls back a transaction from a pending savepoint state.
/// </summary>
[Obsolete("Use Release instead")]
public void ReleaseSavepoint(string name)
{
Release(name);
}
#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.CheckReady();
}
[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
}
}