C# 4 and .NET 4

application recovery ❘ 1403
}
textStatus.Text += String.Format(“{0:T}: Registered for recovery\n”,
DateTime.Now);
App.Source.TraceEvent(TraceEventType.Verbose, 0,
“Registered for recovery”);
DoRecovery() is the callback method that is defined by the RegisterForApplicationRecovery() method
call and is invoked by WER. Within the handler, the Recovery Manager is informed that recovery is in
progress by calling the method ApplicationRecoveryInProgress(). This method returns true if the user
canceled the recovery. You can verify user cancellation during the recovery to stop the recovery in case it
was canceled by the user. Here, the content of the TextBox is written to the temporary file that is used when
restarting the application. At the end of the recovery process, the Restart Manager is informed of its success
by invoking ApplicationRecoveryFinished().
private int DoRecovery(object state)
{
App.Source.TraceEvent(TraceEventType.Verbose, 0, "begin Recovery");
this.tempPath = (string)state;
bool canceled = ApplicationRestartRecoveryManager.
ApplicationRecoveryInProgress();
if (canceled)
{
textStatus.Text += String.Format(
"{0:T}: Recovery canceled, shutting down\n", DateTime.Now);
App.Source.TraceEvent(TraceEventType.Verbose, 0,
"end Recovery with cancel");
ApplicationRestartRecoveryManager.ApplicationRecoveryFinished(
false);
return 0;
}
SaveFile(tempPath);
}
App.Source.TraceEvent(TraceEventType.Verbose, 0, "end Recovery");
ApplicationRestartRecoveryManager.ApplicationRecoveryFinished(true);
return 0;
With all this in place, you can run the application, as shown in
Figure A-2. The TextBlock on the bottom gives status information
such as when registering for restart and recovery happened, and after
60 seconds, information that the application can now crash.
Selecting the menu Action ➪ Crash invokes the handler method
OnCrash(), which does a fast fail. The method Environment.
FailFast() can be used to terminate a process in a fast way.
This method writes an application event log and creates a
dump of the application before the process is terminated. Only
CriticalFinalizerObject objects are executed. Try-finally
blocks and finalizers are not executed.
private void OnCrash(object sender, ExecutedRoutedEventArgs e)
{
Environment.FailFast("RestartDemo stopped from Menu command");
}
After crashing, the application is restarted and you can see the
dialog shown in Figure A-3.
figure a-2
figure a-3
www.it-ebooks.info