private void RecoverSystem(System.Type systemType, CommandLogReader reader, ExceptionDuringRecoveryHandler handler)
 {
     _system = reader.ReadLastSnapshot();
     if (null == _system)
     {
         _system = System.Activator.CreateInstance(systemType);
     }
     RecoverCommands(reader, handler);
 }
        /// <summary>
        /// See <see cref="PrevalenceActivator.CreateEngine(System.Type, string)"/>
        /// </summary>
        /// <param name="systemType"></param>
        /// <param name="prevalenceBase"></param>
        /// <param name="formatter"></param>
        /// <param name="handler"></param>
        internal PrevalenceEngine(System.Type systemType, string prevalenceBase, BinaryFormatter formatter, ExceptionDuringRecoveryHandler handler)
        {
            _clock = new AlarmClock();

            CommandLogReader reader = new CommandLogReader(CheckPrevalenceBase(prevalenceBase), formatter);

            RecoverSystem(systemType, reader, handler);
            _commandLog = reader.ToWriter();
            _lock       = new ReaderWriterLock();
            _decorators = GetCommandDecorators(systemType);
            _paused     = false;
        }
        private void RecoverCommands(CommandLogReader reader, ExceptionDuringRecoveryHandler handler)
        {
            ShareCurrentObject();

            try
            {
                Clock.Pause();
                try
                {
                    foreach (ContextRecoveryCommand contextRecoveryCommand in reader)
                    {
                        Clock.Recover(contextRecoveryCommand.DateTime);

                        ICommand command = contextRecoveryCommand.Command;
                        try
                        {
                            command.Execute(_system);
                        }
                        catch (System.Exception x)
                        {
                            // commands are allowed to throw exceptions
                            // it is up to the client to decide what to
                            // do with them
                            OnExceptionDuringRecovery(handler, command, x);
                        }
                    }
                }
                finally
                {
                    Clock.Resume();
                }
            }
            finally
            {
                UnshareCurrentObject();
            }
        }