The use of QWinOverlappedIoNotifier in QWindowsPipeReader restricts us
in the following ways:
- The handle that gets assigned to QWinOverlappedIoNotifier is forever
tied to an I/O completion port.
- Other notification mechanisms like I/O completion routines of
WriteFileEx do not work with such a handle.
- No other QWinOverlappedIoNotifier can be registered for this handle.
To achieve the ultimate goal of making QWindowsPipeWriter thread-free
(to fix QTBUG-23378 and QTBUG-38185) we remove the usage of
QWinOverlappedIoNotifier from QWindowsPipeReader and use the
ReadFileEx API instead.
This has the additional advantage of removing the need for any thread
synchronization, as the I/O completion routine runs in the thread that
ReadFileEx was called on, leading to simpler and faster code.
Change-Id: I05c983e1f1e49d7dd27e3b77a47f87cae9c3f4c6
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
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