/******************************************************** * 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 System.Data.SQLite { using System; using System.Data; using System.Data.Common; using System.Threading; /// /// SQLite implementation of DbTransaction. /// public sealed class SQLiteTransaction : DbTransaction { /// /// The connection to which this transaction is bound /// internal SQLiteConnection _cnn; internal long _version; // Matches the version of the connection private IsolationLevel _level; /// /// Constructs the transaction object, binding it to the supplied connection /// /// The connection to open a transaction on /// TRUE to defer the writelock, or FALSE to lock immediately 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; } } } /////////////////////////////////////////////////////////////////////////////////////////////// #region IDisposable "Pattern" Members private bool disposed; private void CheckDisposed() /* throw */ { #if THROW_ON_DISPOSED if (disposed) throw new ObjectDisposedException(typeof(SQLiteTransaction).Name); #endif } /////////////////////////////////////////////////////////////////////////////////////////////// /// /// Disposes the transaction. If it is currently active, any changes are rolled back. /// protected override void Dispose(bool disposing) { try { if (!disposed) { if (disposing) { //////////////////////////////////// // dispose managed resources here... //////////////////////////////////// if (IsValid(false)) { IssueRollback(false); } } ////////////////////////////////////// // release unmanaged resources here... ////////////////////////////////////// disposed = true; } } finally { base.Dispose(disposing); } } #endregion /////////////////////////////////////////////////////////////////////////////////////////////// /// /// Commits the current transaction. /// public override void Commit() { CheckDisposed(); SQLiteConnection.Check(_cnn); IsValid(true); if (_cnn._transactionLevel - 1 == 0) { using (SQLiteCommand cmd = _cnn.CreateCommand()) { cmd.CommandText = "COMMIT"; cmd.ExecuteNonQuery(); } } _cnn._transactionLevel--; _cnn = null; } /// /// Returns the underlying connection to which this transaction applies. /// public new SQLiteConnection Connection { get { CheckDisposed(); return _cnn; } } /// /// Forwards to the local Connection property /// protected override DbConnection DbConnection { get { return Connection; } } /// /// Gets the isolation level of the transaction. SQLite only supports Serializable transactions. /// public override IsolationLevel IsolationLevel { get { CheckDisposed(); return _level; } } /// /// Rolls back the active transaction. /// public override void Rollback() { CheckDisposed(); SQLiteConnection.Check(_cnn); IsValid(true); IssueRollback(true); } internal void IssueRollback(bool throwError) { SQLiteConnection cnn = Interlocked.Exchange(ref _cnn, null); if (cnn != null) { try { using (SQLiteCommand cmd = cnn.CreateCommand()) { cmd.CommandText = "ROLLBACK"; cmd.ExecuteNonQuery(); } } catch { if (throwError) throw; } cnn._transactionLevel = 0; } } 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._version != _version) { if (throwError == true) throw new SQLiteException((int)SQLiteErrorCode.Misuse, "The connection was closed and re-opened, changes were already 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; } if (_cnn._transactionLevel == 0 || _cnn._sql.AutoCommit == true) { _cnn._transactionLevel = 0; // Make sure the transaction level is reset before returning if (throwError == true) throw new SQLiteException((int)SQLiteErrorCode.Misuse, "No transaction is active on this connection"); else return false; } return true; } } }