Build 2016 - P489 - Async Programming Improvements for C++ and UWP
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In this video, you’ll see how C++ Coroutines can dramatically simplify the Async coding pattern for UWP, whilst boosting readability and maintainability. As with many other languages, C++ now has an “await”-like feature that lets functions suspend and resume without blocking their threads. The new C++ co_await keyword can be used with both standard C++ and C++/CX, and is supported for both Universal Windows Apps and Classic Windows Apps.
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Build 2016 - P489 - Async Programming Improvements for C++ and UWP
- 5. Demo: Opening a JPG Using PPL tasks
- 6. using namespace Windows::Storage::Pickers; using namespace concurrency; auto picker = ref new FileOpenPicker(); picker->FileTypeFilter->Append(L".jpg"); picker->SuggestedStartLocation = PickerLocationId::PicturesLibrary; create_task(picker->PickSingleFileAsync()).then([this] (Windows::Storage::StorageFile^ file) { create_task(file->OpenReadAsync()).then([this] (Windows::Storage::Streams::IRandomAccessStreamWithContentType^ stream) { auto bitmap = ref new BitmapImage(); bitmap->SetSource(stream); theImage->Source = bitmap; }); });
- 7. using namespace Windows::Storage::Pickers; using namespace concurrency; auto picker = ref new FileOpenPicker(); picker->FileTypeFilter->Append(L".jpg"); picker->SuggestedStartLocation = PickerLocationId::PicturesLibrary; create_task(picker->PickSingleFileAsync()).then([this] (Windows::Storage::StorageFile^ file) { create_task(file->OpenReadAsync()).then([this] (Windows::Storage::Streams::IRandomAccessStreamWithContentType^ stream) { auto bitmap = ref new BitmapImage(); bitmap->SetSource(stream); theImage->Source = bitmap; }); });
- 8. using namespace Windows::Storage::Pickers; using namespace concurrency; auto picker = ref new FileOpenPicker(); picker->FileTypeFilter->Append(L".jpg"); picker->SuggestedStartLocation = PickerLocationId::PicturesLibrary; create_task(picker->PickSingleFileAsync()).then([this] (Windows::Storage::StorageFile^ file) { create_task(file->OpenReadAsync()).then([this] (Windows::Storage::Streams::IRandomAccessStreamWithContentType^ stream) { auto bitmap = ref new BitmapImage(); bitmap->SetSource(stream); theImage->Source = bitmap; }); });
- 9. using namespace Windows::Storage::Pickers; using namespace concurrency; auto picker = ref new FileOpenPicker(); picker->FileTypeFilter->Append(L".jpg"); picker->SuggestedStartLocation = PickerLocationId::PicturesLibrary; create_task(picker->PickSingleFileAsync()).then([this] (Windows::Storage::StorageFile^ file) { create_task(file->OpenReadAsync()).then([this] (Windows::Storage::Streams::IRandomAccessStreamWithContentType^ stream) { auto bitmap = ref new BitmapImage(); bitmap->SetSource(stream); theImage->Source = bitmap; }); });
- 12. void ShowImage() { auto picker = ref new FileOpenPicker(); picker->FileTypeFilter->Append(L".jpg"); picker->SuggestedStartLocation = PickerLocationId::PicturesLibrary; auto file = picker->PickSingleFile(); auto stream = file->OpenRead(); auto bitmap = ref new BitmapImage(); bitmap->SetSource(stream); theImage->Source = bitmap; }
- 13. asynchronous task<void> ShowImageAsync() { auto picker = ref new FileOpenPicker(); picker->FileTypeFilter->Append(L".jpg"); picker->SuggestedStartLocation = PickerLocationId::PicturesLibrary; auto file = co_await picker->PickSingleFileAsync(); auto stream = co_await file->OpenReadAsync(); auto bitmap = ref new BitmapImage(); bitmap->SetSource(stream); theImage->Source = bitmap; }
- 14. Demo: Opening a JPG (redux) Using co_await
- 15. future<void> do_while(function<future<bool>()> body) { return body().then([=](future<bool> notDone) { return notDone.get() ? do_while(body) : make_ready_future(); }); } future<int> tcp_reader(int total) { struct State { char buf[4 * 1024]; int total; Tcp::Connection conn; explicit State(int total) : total(total) {} }; auto state = make_shared<State>(total); return Tcp::Connect("127.0.0.1", 1337).then( [state](future<Tcp::Connection> conn) { state->conn = std::move(conn); return do_while([state]()->future<bool> { if (state->total <= 0) return make_ready_future(false); return state->conn.read(state->buf, sizeof(state->buf)).then( [state](future<int> nBytesFut) { auto nBytes = nBytesFut.get() if (nBytes == 0) return make_ready_future(false); state->total -= nBytes; return make_ready_future(true); }); }); }); } auto tcp_reader(int total) -> future<int> { char buf[4 * 1024]; auto conn = co_await Tcp::Connect("127.0.0.1", 1337); for (;;) { auto bytesRead = co_await conn.Read(buf, sizeof(buf)); total -= bytesRead; if (total <= 0 || bytesRead == 0) return total; } }
- 17. DART 1.9 Future<int> getPage(t) async { var c = new http.Client(); try { var r = await c.get('http://url/search?q=$t'); print(r); return r.length(); } finally { await c.close(); } } C# async Task<string> WaitAsynchronouslyAsync() { await Task.Delay(10000); return "Finished"; } HACK (programming language) async function gen1(): Awaitable<int> { $x = await Batcher::fetch(1); $y = await Batcher::fetch(2); return $x + $y; } Python: PEP 0492 async def abinary(n): if n <= 0: return 1 l = await abinary(n - 1) r = await abinary(n - 1) return l + 1 + r C++1z future<string> WaitAsynchronouslyAsync() { co_await sleep_for(10ms); co_return "Finished"s; }
- 19. User Coroutine designer Async Generator co_await + co_yield Generator co_yield Task co_await Plain old function Compiler does not care
- 20. co_await co_return co_yield await $p.yield_value(expr)