// LOLLO NOTE important! The Mutex can work across AppDomains (ie across main app and background task) but only if you give it a name!
// Also, if you declare initially owned true, the second thread trying to cross it will stay locked forever. So, declare it false.
// All this is not well documented.
public static async Task LoadAsync()
{
string errorMessage = string.Empty;
try
{
await _suspensionSemaphore.WaitAsync().ConfigureAwait(false);
if (_isLoaded)
{
return;
}
var file = await ApplicationData.Current.LocalCacheFolder.CreateFileAsync(SessionDataFilename, CreationCollisionOption.OpenIfExists).AsTask().ConfigureAwait(false);
//string ssss = null; //this is useful when you debug and want to see the file as a string
//using (IInputStream inStream = await file.OpenSequentialReadAsync())
//{
// using (StreamReader streamReader = new StreamReader(inStream.AsStreamForRead()))
// {
// ssss = streamReader.ReadToEnd();
// }
//}
using (IInputStream inStream = await file.OpenSequentialReadAsync().AsTask().ConfigureAwait(false))
{
using (var iinStream = inStream.AsStreamForRead())
{
DataContractSerializer serializer = new DataContractSerializer(typeof(PersistentData));
iinStream.Position = 0;
PersistentData newPersistentData = (PersistentData)(serializer.ReadObject(iinStream));
await iinStream.FlushAsync().ConfigureAwait(false);
PersistentData.GetInstanceWithProperties(newPersistentData);
}
}
Debug.WriteLine("ended reading settings");
}
catch (System.Xml.XmlException ex)
{
errorMessage = "could not restore the settings";
await Logger.AddAsync(ex.ToString(), Logger.FileErrorLogFilename);
}
catch (Exception ex)
{
errorMessage = "could not restore the settings";
await Logger.AddAsync(ex.ToString(), Logger.FileErrorLogFilename);
}
finally
{
PersistentData.GetInstance().LastMessage = errorMessage;
IsLoaded = true;
SemaphoreSlimSafeRelease.TryRelease(_suspensionSemaphore);
}
}
//protected Func<Task> _runAsSoonAsOpen = null;
#endregion properties
#region open close
public async Task <bool> OpenAsync(object args = null)
{
if (_isOpen)
{
return(false);
}
lock (_isOpenSemaphoreLocker)
{
if (!SemaphoreSlimSafeRelease.IsAlive(_isOpenSemaphore))
{
_isOpenSemaphore = new SemaphoreSlimSafeRelease(1, 1);
}
}
try
{
await _isOpenSemaphore.WaitAsync().ConfigureAwait(false);
if (!_isOpen)
{
lock (_ctsLocker)
{
_cts?.Dispose();
_cts = new SafeCancellationTokenSource();
_cancToken = _cts.Token;
}
await OpenMayOverrideAsync(args).ConfigureAwait(false);
IsOpen = true;
return(true);
}
}
catch (Exception ex)
{
if (SemaphoreSlimSafeRelease.IsAlive(_isOpenSemaphore))
{
await Logger.AddAsync(GetType().Name + ex.ToString(), Logger.ForegroundLogFilename);
}
}
finally
{
SemaphoreSlimSafeRelease.TryRelease(_isOpenSemaphore);
}
return(false);
}
public async Task <bool> OpenAsync(object args = null)
{
if (_isOpen)
{
return(await RunFunctionIfOpenAsyncA(delegate { IsEnabledAllowed = true; }).ConfigureAwait(false));
}
lock (_isOpenSemaphoreLocker)
{
if (!SemaphoreSlimSafeRelease.IsAlive(_isOpenSemaphore))
{
_isOpenSemaphore = new SemaphoreSlimSafeRelease(1, 1);
}
}
try
{
await _isOpenSemaphore.WaitAsync().ConfigureAwait(false);
if (!_isOpen)
{
lock (_ctsLocker)
{
_cts?.Dispose();
_cts = new SafeCancellationTokenSource();
_cancToken = _cts.Token;
}
await OpenMayOverrideAsync(args).ConfigureAwait(false);
IsOpen = true;
IsEnabledAllowed = true;
await RegisterBackEventHandlersAsync().ConfigureAwait(false);
//Logger.Add_TPL($"OpenableObservablePage.OpenAsync: {GetType().Name} is now open", Logger.AppEventsLogFilename, Logger.Severity.Info, false);
return(true);
}
}
catch (Exception ex)
{
if (SemaphoreSlimSafeRelease.IsAlive(_isOpenSemaphore))
{
await Logger.AddAsync(GetType().Name + ex.ToString(), Logger.ForegroundLogFilename);
}
}
finally
{
SemaphoreSlimSafeRelease.TryRelease(_isOpenSemaphore);
}
return(false);
}
