protected Timer ProcessRetriesUsingTimer(Func <bool> attempter, Action <OperationResultEventArgs> callback)
{
int tryCount = 0;
Timer timer = null;
TimerCallback timerCallback = (state) => {
try {
OperationResultEventArgs resultArgs = null;
try {
resultArgs = TryOnce(attempter, ++tryCount, timer);
}
catch (Exception ex) {
resultArgs = new OperationResultEventArgs(ResultEnum.Failure, ex, tryCount);
}
if (resultArgs != null && callback != null)
{
callback(resultArgs);
}
}
// Supressing all exceptions to avoid an unhandled exception from killing the entire windows process
catch { }
};
// Creating a single-time and immediate timer for the first attempt
timer = new Timer(timerCallback, null, 0, 0);
return(timer);
}
protected BackgroundWorker CreateBackgroundRetryWorker(Func <bool> attempter, Action <OperationResultEventArgs> callback)
{
var worker = new BackgroundWorker();
bool success = false;
int tryCount = 0;
Exception error = null;
// Creating the handler delegate, which creates another delegate itself
worker.DoWork +=
delegate(object sender, DoWorkEventArgs e) {
Func <bool> callWrapper =
delegate {
if (worker.CancellationPending)
{
e.Cancel = true; // Indicate that cancellation occured (no exception)
return(true); // Returning without an exception will end the retry cycle
}
return(attempter());
};
success = TryAll(callWrapper, out tryCount, out error);
};
if (callback != null)
{
worker.RunWorkerCompleted += delegate(object sender, RunWorkerCompletedEventArgs args) {
var result =
args.Error != null ? ResultEnum.Failure :
args.Cancelled ? ResultEnum.Canceled :
ResultEnum.Success;
var resultArgs = new OperationResultEventArgs(result, args.Error ?? error, tryCount);
callback(resultArgs);
};
}
return(worker);
}
protected abstract void NotifyAsyncCallback(OperationResultEventArgs args);