// TODO (CR Apr 2013): the reason this is overloaded is because there's not always a task to return. Would be better
// to return some other object, possibly with the task as a property, but also with the volume itself, if it's available.
private Task LoadAsync(VolumeLoadProgressCallback onProgress = null, VolumeLoadCompletionCallback onComplete = null, VolumeLoadErrorCallback onError = null)
{
AssertNotDisposed();
// TODO (CR Apr 2013): Not a good idea to return nothing; why not return a struct with the volume in it?
if (_volumeReference != null)
{
return(null);
}
if (_backgroundLoadTask != null)
{
return(_backgroundLoadTask);
}
lock (_backgroundLoadSyncRoot)
{
if (_volumeReference != null)
{
return(null);
}
if (_backgroundLoadTask != null)
{
return(_backgroundLoadTask);
}
_backgroundLoadTask = new Task(() => LoadCore(onProgress));
_backgroundLoadTask.ContinueWith(t =>
{
// TODO (CR Apr 2013): Can probably just lock the part that
// changes the _backgroundLoadTask variable.
lock (_backgroundLoadSyncRoot)
{
if (t.IsFaulted && t.Exception != null)
{
var ex = t.Exception.Flatten().InnerExceptions.FirstOrDefault();
if (onError != null)
{
onError.Invoke(this, ex);
}
else
{
Platform.Log(LogLevel.Warn, ex, "Unhandled exception thrown in background volume loader");
}
}
else
{
if (onComplete != null)
{
onComplete.Invoke(this);
}
}
if (ReferenceEquals(t, _backgroundLoadTask))
{
_backgroundLoadTask.Dispose();
_backgroundLoadTask = null;
}
}
});
_backgroundLoadTask.Start();
return(_backgroundLoadTask);
}
}
// TODO (CR Apr 2013): API is a bit overloaded; the task provides completion and error info already
// so probably all that is needed is the progress callback argument.
public Task LoadAsync(VolumeLoadProgressCallback onProgress = null, VolumeLoadCompletionCallback onComplete = null, VolumeLoadErrorCallback onError = null)
{
return(_cachedVolume.LoadAsync(onProgress, onComplete, onError));
}
private IAsyncResult LoadAsync(VolumeLoadProgressCallback onProgress = null, VolumeLoadCompletionCallback onComplete = null, VolumeLoadErrorCallback onError = null)
{
AssertNotDisposed();
if (_volumeReference != null)
{
return(null);
}
if (_backgroundLoadMethod != null)
{
return(_backgroundLoadMethodAsyncResult);
}
lock (_backgroundLoadSyncRoot)
{
if (_volumeReference != null)
{
return(null);
}
if (_backgroundLoadMethod != null)
{
return(_backgroundLoadMethodAsyncResult);
}
_backgroundLoadMethod = () =>
{
try
{
LoadCore(onProgress);
if (onComplete != null)
{
onComplete.Invoke(this);
}
}
catch (Exception ex)
{
if (onError != null)
{
onError.Invoke(this, ex);
}
else
{
Platform.Log(LogLevel.Debug, ex, "Unhandled exception thrown in asynchronous volume loader");
}
}
};
return(_backgroundLoadMethodAsyncResult = _backgroundLoadMethod.BeginInvoke(ar =>
{
_backgroundLoadMethod.EndInvoke(ar);
_backgroundLoadMethod = null;
_backgroundLoadMethodAsyncResult = null;
}, null));
}
}
