/// <summary>
/// Helper method to use async/await with IAsyncServiceProvider implementation
/// </summary>
/// <param name="asyncServiceProvider">IAsyncServciceProvider instance</param>
/// <param name="serviceType">Type of the Visual Studio service requested</param>
/// <returns>Service object as type of T</returns>
public static async Task <T> GetServiceAsync <T>(this Microsoft.VisualStudio.Shell.Interop.COMAsyncServiceProvider.IAsyncServiceProvider asyncServiceProvider, Type serviceType) where T : class
{
T returnValue = null;
await ThreadHelper.JoinableTaskFactory.RunAsync(async() =>
{
object serviceInstance = null;
Guid serviceTypeGuid = serviceType.GUID;
serviceInstance = await asyncServiceProvider.QueryServiceAsync(ref serviceTypeGuid);
// We have to make sure we are on main UI thread before trying to cast as underlying implementation
// can be an STA COM object and doing a cast would require calling QueryInterface/AddRef marshaling
// to main thread via COM.
await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
returnValue = serviceInstance as T;
});
return(returnValue);
}
private async Task <IVsContainedLanguageFactory?> GetContainedLanguageFactoryAsync()
{
Guid languageServiceId = await GetLanguageServiceIdAsync();
if (languageServiceId == Guid.Empty)
{
return(null);
}
IOleAsyncServiceProvider serviceProvider = await _serviceProvider.GetValueAsync();
object?service = await serviceProvider.QueryServiceAsync(languageServiceId);
// NOTE: While this type is implemented in Roslyn, we force the cast on
// the UI thread because they are free to change this to an STA object
// which would result in an RPC call from a background thread.
await _projectVsServices.ThreadingService.SwitchToUIThread();
return(service as IVsContainedLanguageFactory);
}
