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/********************************************************
* ADO.NET 2.0 Data Provider for SQLite Version 3.X
* Written by Robert Simpson (robert@blackcastlesoft.com)
*
* Released to the public domain, use at your own risk!
********************************************************/
namespace Mono.Data.Sqlite
{
using System;
using System.Data;
using System.Data.Common;
/// <summary>
/// SQLite implementation of DbTransaction.
/// </summary>
public sealed class SqliteTransaction : DbTransaction
{
/// <summary>
/// The connection to which this transaction is bound
/// </summary>
internal SqliteConnection _cnn;
internal long _version; // Matches the version of the connection
private IsolationLevel _level;
/// <summary>
/// Constructs the transaction object, binding it to the supplied connection
/// </summary>
/// <param name="connection">The connection to open a transaction on</param>
/// <param name="deferredLock">TRUE to defer the writelock, or FALSE to lock immediately</param>
internal SqliteTransaction(SqliteConnection connection, bool deferredLock)
{
_cnn = connection;
_version = _cnn._version;
_level = (deferredLock == true) ? IsolationLevel.ReadCommitted : IsolationLevel.Serializable;
if (_cnn._transactionLevel++ == 0)
{
try
{
using (SqliteCommand cmd = _cnn.CreateCommand())
{
if (!deferredLock)
cmd.CommandText = "BEGIN IMMEDIATE";
else
cmd.CommandText = "BEGIN";
cmd.ExecuteNonQuery();
}
}
catch (SqliteException)
{
_cnn._transactionLevel--;
_cnn = null;
throw;
}
}
}
/// <summary>
/// Commits the current transaction.
/// </summary>
public override void Commit()
{
IsValid(true);
if (_cnn._transactionLevel - 1 == 0)
{
using (SqliteCommand cmd = _cnn.CreateCommand())
{
cmd.CommandText = "COMMIT";
cmd.ExecuteNonQuery();
}
}
_cnn._transactionLevel--;
_cnn = null;
}
/// <summary>
/// Returns the underlying connection to which this transaction applies.
/// </summary>
public new SqliteConnection Connection
{
get { return _cnn; }
}
/// <summary>
/// Forwards to the local Connection property
/// </summary>
protected override DbConnection DbConnection
{
get { return Connection; }
}
/// <summary>
/// Disposes the transaction. If it is currently active, any changes are rolled back.
/// </summary>
protected override void Dispose(bool disposing)
{
if (disposing)
{
lock (this)
{
if (IsValid(false))
Rollback();
_cnn = null;
}
}
base.Dispose(disposing);
}
/// <summary>
/// Gets the isolation level of the transaction. SQLite only supports Serializable transactions.
/// </summary>
public override IsolationLevel IsolationLevel
{
get { return _level; }
}
/// <summary>
/// Rolls back the active transaction.
/// </summary>
public override void Rollback()
{
IsValid(true);
IssueRollback(_cnn);
_cnn._transactionLevel = 0;
_cnn = null;
}
internal static void IssueRollback(SqliteConnection cnn)
{
using (SqliteCommand cmd = cnn.CreateCommand())
{
cmd.CommandText = "ROLLBACK";
cmd.ExecuteNonQuery();
}
}
internal bool IsValid(bool throwError)
{
if (_cnn == null)
{
if (throwError == true) throw new ArgumentNullException("No connection associated with this transaction");
else return false;
}
if (_cnn._transactionLevel == 0)
{
if (throwError == true) throw new SqliteException((int)SQLiteErrorCode.Misuse, "No transaction is active on this connection");
else return false;
}
if (_cnn._version != _version)
{
if (throwError == true) throw new SqliteException((int)SQLiteErrorCode.Misuse, "The connection was closed and re-opened, changes were rolled back");
else return false;
}
if (_cnn.State != ConnectionState.Open)
{
if (throwError == true) throw new SqliteException((int)SQLiteErrorCode.Misuse, "Connection was closed");
else return false;
}
return true;
}
}
}
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