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winrt: Add convenience method for waiting on an async call

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As most of the Windows Runtime API is asynchronous, we have used various
methods for blocking in the calling thread waiting for the operation to
complete. This introduces an inline method, QWinRTFunctions::await(),
which performs the wait in a consistent and safe manner.

Task-number: QTBUG-39407
Change-Id: I54cd0e178aa560891ab92bfc5e7a6553e60e01b2
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@digia.com>
This commit is contained in:
Andrew Knight 2014-06-06 14:15:12 +03:00
parent 6d95ce1649
commit 164ae66ff7
1 changed files with 78 additions and 0 deletions
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78
src/corelib/kernel/qfunctions_winrt.h
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@ -46,6 +46,10 @@
#ifdef Q_OS_WINRT
#include <QtCore/QThread>
#include <QtCore/QAbstractEventDispatcher>
#include <QtCore/qt_windows.h>
QT_BEGIN_NAMESPACE
#ifdef QT_BUILD_CORE_LIB
@ -133,5 +137,79 @@ generate_inline_return_func0(_tzset, void)
#define Q_ASSERT_SUCCEEDED(hr) \
Q_ASSERT_X(SUCCEEDED(hr), Q_FUNC_INFO, qPrintable(qt_error_string(hr)));
namespace Microsoft { namespace WRL { template <typename T> class ComPtr; } }
namespace QWinRTFunctions {
// Synchronization methods
enum AwaitStyle
{
YieldThread = 0,
ProcessThreadEvents = 1,
ProcessMainThreadEvents = 2
};
template <typename T>
static inline HRESULT _await_impl(const Microsoft::WRL::ComPtr<T> &asyncOp, AwaitStyle awaitStyle)
{
Microsoft::WRL::ComPtr<IAsyncInfo> asyncInfo;
HRESULT hr = asyncOp.As(&asyncInfo);
if (FAILED(hr))
return hr;
AsyncStatus status;
switch (awaitStyle) {
case ProcessMainThreadEvents:
while (SUCCEEDED(hr = asyncInfo->get_Status(&status)) && status == Started)
QCoreApplication::processEvents();
break;
case ProcessThreadEvents:
if (QAbstractEventDispatcher *dispatcher = QThread::currentThread()->eventDispatcher()) {
while (SUCCEEDED(hr = asyncInfo->get_Status(&status)) && status == Started)
dispatcher->processEvents(QEventLoop::AllEvents);
break;
}
// fall through
default:
case YieldThread:
while (SUCCEEDED(hr = asyncInfo->get_Status(&status)) && status == Started)
QThread::yieldCurrentThread();
break;
}
if (FAILED(hr) || status != Completed) {
HRESULT ec;
hr = asyncInfo->get_ErrorCode(&ec);
if (FAILED(hr))
return hr;
return ec;
}
return hr;
}
template <typename T>
static inline HRESULT await(const Microsoft::WRL::ComPtr<T> &asyncOp, AwaitStyle awaitStyle = YieldThread)
{
HRESULT hr = _await_impl(asyncOp, awaitStyle);
if (FAILED(hr))
return hr;
return asyncOp->GetResults();
}
template <typename T, typename U>
static inline HRESULT await(const Microsoft::WRL::ComPtr<T> &asyncOp, U *results, AwaitStyle awaitStyle = YieldThread)
{
HRESULT hr = _await_impl(asyncOp, awaitStyle);
if (FAILED(hr))
return hr;
return asyncOp->GetResults(results);
}
} // QWinRTFunctions
#endif // Q_OS_WINRT
#endif // QFUNCTIONS_WINRT_H