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Diffstat (limited to 'src/serialport/qwinoverlappedionotifier.cpp')
| -rw-r--r-- | src/serialport/qwinoverlappedionotifier.cpp | 420 |
1 files changed, 420 insertions, 0 deletions
diff --git a/src/serialport/qwinoverlappedionotifier.cpp b/src/serialport/qwinoverlappedionotifier.cpp new file mode 100644 index 0000000..dfae3b0 --- /dev/null +++ b/src/serialport/qwinoverlappedionotifier.cpp @@ -0,0 +1,420 @@ +/**************************************************************************** +** +** Copyright (C) 2016 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the QtCore module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "qwinoverlappedionotifier_p.h" +#include <qdebug.h> +#include <qatomic.h> +#include <qelapsedtimer.h> +#include <qmutex.h> +#include <qpointer.h> +#include <qqueue.h> +#include <qset.h> +#include <qthread.h> +#include <qt_windows.h> +#include <private/qobject_p.h> +#include <private/qiodevice_p.h> + +QT_BEGIN_NAMESPACE + +/*! + \class QWinOverlappedIoNotifier + \inmodule QtCore + \brief The QWinOverlappedIoNotifier class provides support for overlapped I/O notifications on Windows. + \since 5.0 + \internal + + The QWinOverlappedIoNotifier class makes it possible to use efficient + overlapped (asynchronous) I/O notifications on Windows by using an + I/O completion port. + + Once you have obtained a file handle, you can use setHandle() to get + notifications for I/O operations. Whenever an I/O operation completes, + the notified() signal is emitted which will pass the number of transferred + bytes, the operation's error code and a pointer to the operation's + OVERLAPPED object to the receiver. + + Every handle that supports overlapped I/O can be used by + QWinOverlappedIoNotifier. That includes file handles, TCP sockets + and named pipes. + + Note that you must not use ReadFileEx() and WriteFileEx() together + with QWinOverlappedIoNotifier. They are not supported as they use a + different I/O notification mechanism. + + The hEvent member in the OVERLAPPED structure passed to ReadFile() + or WriteFile() is ignored and can be used for other purposes. + + \warning This class is only available on Windows. + + Due to peculiarities of the Windows I/O completion port API, users of + QWinOverlappedIoNotifier must pay attention to the following restrictions: + \list + \li File handles with a QWinOverlappedIoNotifer are assigned to an I/O + completion port until the handle is closed. It is impossible to + disassociate the file handle from the I/O completion port. + \li There can be only one QWinOverlappedIoNotifer per file handle. Creating + another QWinOverlappedIoNotifier for that file, even with a duplicated + handle, will fail. + \li Certain Windows API functions are unavailable for file handles that are + assigned to an I/O completion port. This includes the functions + \c{ReadFileEx} and \c{WriteFileEx}. + \endlist + See also the remarks in the MSDN documentation for the + \c{CreateIoCompletionPort} function. +*/ + +struct IOResult +{ + IOResult(DWORD n = 0, DWORD e = 0, OVERLAPPED *p = nullptr) + : numberOfBytes(n), errorCode(e), overlapped(p) + {} + + DWORD numberOfBytes = 0; + DWORD errorCode = 0; + OVERLAPPED *overlapped = nullptr; +}; + + +class QWinIoCompletionPort; + +class QWinOverlappedIoNotifierPrivate : public QObjectPrivate +{ + Q_DECLARE_PUBLIC(QWinOverlappedIoNotifier) +public: + OVERLAPPED *waitForAnyNotified(QDeadlineTimer deadline); + void notify(DWORD numberOfBytes, DWORD errorCode, OVERLAPPED *overlapped); + void _q_notified(); + OVERLAPPED *dispatchNextIoResult(); + + static QWinIoCompletionPort *iocp; + static HANDLE iocpInstanceLock; + static unsigned int iocpInstanceRefCount; + HANDLE hHandle = INVALID_HANDLE_VALUE; + HANDLE hSemaphore = nullptr; + HANDLE hResultsMutex = nullptr; + QAtomicInt waiting; + QQueue<IOResult> results; +}; + +QWinIoCompletionPort *QWinOverlappedIoNotifierPrivate::iocp = 0; +HANDLE QWinOverlappedIoNotifierPrivate::iocpInstanceLock = CreateMutex(NULL, FALSE, NULL); +unsigned int QWinOverlappedIoNotifierPrivate::iocpInstanceRefCount = 0; + + +class QWinIoCompletionPort : protected QThread +{ +public: + QWinIoCompletionPort() + : finishThreadKey(reinterpret_cast<ULONG_PTR>(this)), + drainQueueKey(reinterpret_cast<ULONG_PTR>(this + 1)) + { + setObjectName(QLatin1String("I/O completion port thread")); + HANDLE hIOCP = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0); + if (!hIOCP) { + qErrnoWarning("CreateIoCompletionPort failed."); + return; + } + hPort = hIOCP; + hQueueDrainedEvent = CreateEvent(NULL, TRUE, FALSE, NULL); + if (!hQueueDrainedEvent) { + qErrnoWarning("CreateEvent failed."); + return; + } + } + + ~QWinIoCompletionPort() + { + PostQueuedCompletionStatus(hPort, 0, finishThreadKey, NULL); + QThread::wait(); + CloseHandle(hPort); + CloseHandle(hQueueDrainedEvent); + } + + void registerNotifier(QWinOverlappedIoNotifierPrivate *notifier) + { + const HANDLE hHandle = notifier->hHandle; + HANDLE hIOCP = CreateIoCompletionPort(hHandle, hPort, + reinterpret_cast<ULONG_PTR>(notifier), 0); + if (!hIOCP) { + qErrnoWarning("Can't associate file handle %x with I/O completion port.", hHandle); + return; + } + mutex.lock(); + notifiers += notifier; + mutex.unlock(); + if (!QThread::isRunning()) + QThread::start(); + } + + void unregisterNotifier(QWinOverlappedIoNotifierPrivate *notifier) + { + mutex.lock(); + notifiers.remove(notifier); + mutex.unlock(); + } + + void drainQueue() + { + QMutexLocker locker(&drainQueueMutex); + ResetEvent(hQueueDrainedEvent); + PostQueuedCompletionStatus(hPort, 0, drainQueueKey, NULL); + WaitForSingleObject(hQueueDrainedEvent, INFINITE); + } + + using QThread::isRunning; + +protected: + void run() + { + DWORD dwBytesRead = 0; + ULONG_PTR pulCompletionKey = 0; + OVERLAPPED *overlapped = nullptr; + DWORD msecs = INFINITE; + + forever { + BOOL success = GetQueuedCompletionStatus(hPort, + &dwBytesRead, + &pulCompletionKey, + &overlapped, + msecs); + + DWORD errorCode = success ? ERROR_SUCCESS : GetLastError(); + if (!success && !overlapped) { + if (!msecs) { + // Time out in drain mode. The completion status queue is empty. + msecs = INFINITE; + SetEvent(hQueueDrainedEvent); + continue; + } + qErrnoWarning(errorCode, "GetQueuedCompletionStatus failed."); + return; + } + + if (pulCompletionKey == finishThreadKey) + return; + if (pulCompletionKey == drainQueueKey) { + // Enter drain mode. + Q_ASSERT(msecs == INFINITE); + msecs = 0; + continue; + } + + QWinOverlappedIoNotifierPrivate *notifier + = reinterpret_cast<QWinOverlappedIoNotifierPrivate *>(pulCompletionKey); + mutex.lock(); + if (notifiers.contains(notifier)) + notifier->notify(dwBytesRead, errorCode, overlapped); + mutex.unlock(); + } + } + +private: + const ULONG_PTR finishThreadKey; + const ULONG_PTR drainQueueKey; + HANDLE hPort = INVALID_HANDLE_VALUE; + QSet<QWinOverlappedIoNotifierPrivate *> notifiers; + QMutex mutex; + QMutex drainQueueMutex; + HANDLE hQueueDrainedEvent = nullptr; +}; + + +QWinOverlappedIoNotifier::QWinOverlappedIoNotifier(QObject *parent) + : QObject(*new QWinOverlappedIoNotifierPrivate, parent) +{ + Q_D(QWinOverlappedIoNotifier); + WaitForSingleObject(d->iocpInstanceLock, INFINITE); + if (!d->iocp) + d->iocp = new QWinIoCompletionPort; + d->iocpInstanceRefCount++; + ReleaseMutex(d->iocpInstanceLock); + + d->hSemaphore = CreateSemaphore(NULL, 0, 255, NULL); + d->hResultsMutex = CreateMutex(NULL, FALSE, NULL); + connect(this, SIGNAL(_q_notify()), this, SLOT(_q_notified()), Qt::QueuedConnection); +} + +QWinOverlappedIoNotifier::~QWinOverlappedIoNotifier() +{ + Q_D(QWinOverlappedIoNotifier); + setEnabled(false); + CloseHandle(d->hResultsMutex); + CloseHandle(d->hSemaphore); + + WaitForSingleObject(d->iocpInstanceLock, INFINITE); + if (!--d->iocpInstanceRefCount) { + delete d->iocp; + d->iocp = 0; + } + ReleaseMutex(d->iocpInstanceLock); +} + +void QWinOverlappedIoNotifier::setHandle(Qt::HANDLE h) +{ + Q_D(QWinOverlappedIoNotifier); + d->hHandle = h; +} + +Qt::HANDLE QWinOverlappedIoNotifier::handle() const +{ + Q_D(const QWinOverlappedIoNotifier); + return d->hHandle; +} + +void QWinOverlappedIoNotifier::setEnabled(bool enabled) +{ + Q_D(QWinOverlappedIoNotifier); + if (enabled) + d->iocp->registerNotifier(d); + else + d->iocp->unregisterNotifier(d); +} + +OVERLAPPED *QWinOverlappedIoNotifierPrivate::waitForAnyNotified(QDeadlineTimer deadline) +{ + if (!iocp->isRunning()) { + qWarning("Called QWinOverlappedIoNotifier::waitForAnyNotified on inactive notifier."); + return 0; + } + + DWORD msecs = deadline.remainingTime(); + if (msecs == 0) + iocp->drainQueue(); + if (msecs == -1) + msecs = INFINITE; + + const DWORD wfso = WaitForSingleObject(hSemaphore, msecs); + switch (wfso) { + case WAIT_OBJECT_0: + return dispatchNextIoResult(); + case WAIT_TIMEOUT: + return 0; + default: + qErrnoWarning("QWinOverlappedIoNotifier::waitForAnyNotified: WaitForSingleObject failed."); + return 0; + } +} + +class QScopedAtomicIntIncrementor +{ +public: + QScopedAtomicIntIncrementor(QAtomicInt &i) + : m_int(i) + { + ++m_int; + } + + ~QScopedAtomicIntIncrementor() + { + --m_int; + } + +private: + QAtomicInt &m_int; +}; + +/*! + * Wait synchronously for any notified signal. + * + * The function returns a pointer to the OVERLAPPED object corresponding to the completed I/O + * operation. In case no I/O operation was completed during the \a msec timeout, this function + * returns a null pointer. + */ +OVERLAPPED *QWinOverlappedIoNotifier::waitForAnyNotified(QDeadlineTimer deadline) +{ + Q_D(QWinOverlappedIoNotifier); + QScopedAtomicIntIncrementor saii(d->waiting); + OVERLAPPED *result = d->waitForAnyNotified(deadline); + return result; +} + +/*! + * Wait synchronously for the notified signal. + * + * The function returns true if the notified signal was emitted for + * the I/O operation that corresponds to the OVERLAPPED object. + */ +bool QWinOverlappedIoNotifier::waitForNotified(QDeadlineTimer deadline, OVERLAPPED *overlapped) +{ + Q_D(QWinOverlappedIoNotifier); + QScopedAtomicIntIncrementor saii(d->waiting); + while (!deadline.hasExpired()) { + OVERLAPPED *triggeredOverlapped = waitForAnyNotified(deadline); + if (!triggeredOverlapped) + return false; + if (triggeredOverlapped == overlapped) + return true; + } + return false; +} + +/*! + * Note: This function runs in the I/O completion port thread. + */ +void QWinOverlappedIoNotifierPrivate::notify(DWORD numberOfBytes, DWORD errorCode, + OVERLAPPED *overlapped) +{ + Q_Q(QWinOverlappedIoNotifier); + WaitForSingleObject(hResultsMutex, INFINITE); + results.enqueue(IOResult(numberOfBytes, errorCode, overlapped)); + ReleaseMutex(hResultsMutex); + ReleaseSemaphore(hSemaphore, 1, NULL); + if (!waiting) + emit q->_q_notify(); +} + +void QWinOverlappedIoNotifierPrivate::_q_notified() +{ + if (WaitForSingleObject(hSemaphore, 0) == WAIT_OBJECT_0) + dispatchNextIoResult(); +} + +OVERLAPPED *QWinOverlappedIoNotifierPrivate::dispatchNextIoResult() +{ + Q_Q(QWinOverlappedIoNotifier); + WaitForSingleObject(hResultsMutex, INFINITE); + IOResult ioresult = results.dequeue(); + ReleaseMutex(hResultsMutex); + emit q->notified(ioresult.numberOfBytes, ioresult.errorCode, ioresult.overlapped); + return ioresult.overlapped; +} + +QT_END_NAMESPACE + +#include "moc_qwinoverlappedionotifier_p.cpp" |