diff options
Diffstat (limited to 'src/serialport/qwinoverlappedionotifier.cpp')
| -rw-r--r-- | src/serialport/qwinoverlappedionotifier.cpp | 78 |
1 files changed, 36 insertions, 42 deletions
diff --git a/src/serialport/qwinoverlappedionotifier.cpp b/src/serialport/qwinoverlappedionotifier.cpp index 08561685..3e85fd84 100644 --- a/src/serialport/qwinoverlappedionotifier.cpp +++ b/src/serialport/qwinoverlappedionotifier.cpp @@ -1,41 +1,5 @@ -/**************************************************************************** -** -** 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. -** -** $QT_END_LICENSE$ -** -****************************************************************************/ +// Copyright (C) 2016 The Qt Company Ltd. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only #include "qwinoverlappedionotifier_p.h" #include <qdebug.h> @@ -129,6 +93,7 @@ public: HANDLE hSemaphore = nullptr; HANDLE hResultsMutex = nullptr; QAtomicInt waiting; + QAtomicInt signalSent; QQueue<IOResult> results; }; @@ -395,16 +360,45 @@ void QWinOverlappedIoNotifierPrivate::notify(DWORD numberOfBytes, DWORD errorCod Q_Q(QWinOverlappedIoNotifier); WaitForSingleObject(hResultsMutex, INFINITE); results.enqueue(IOResult(numberOfBytes, errorCode, overlapped)); - ReleaseMutex(hResultsMutex); ReleaseSemaphore(hSemaphore, 1, NULL); - if (!waiting) + ReleaseMutex(hResultsMutex); + // Do not send a signal if we didn't process the previous one. + // This is done to prevent soft memory leaks when working in a completely + // synchronous way. + if (!waiting && !signalSent.loadAcquire()) { + signalSent.storeRelease(1); emit q->_q_notify(); + } } void QWinOverlappedIoNotifierPrivate::_q_notified() { - if (WaitForSingleObject(hSemaphore, 0) == WAIT_OBJECT_0) - dispatchNextIoResult(); + Q_Q(QWinOverlappedIoNotifier); + signalSent.storeRelease(0); // signal processed - ready for a new one + if (WaitForSingleObject(hSemaphore, 0) == WAIT_OBJECT_0) { + // As we do not queue signals anymore, we need to process the whole + // queue at once. + WaitForSingleObject(hResultsMutex, INFINITE); + QQueue<IOResult> values; + results.swap(values); + // Decreasing the semaphore count to keep it in sync with the number + // of messages in queue. As ReleaseSemaphore does not accept negative + // values, this is sort of a recommended way to go: + // https://learn.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-releasesemaphore#remarks + int numToDecrease = values.size() - 1; + while (numToDecrease > 0) { + WaitForSingleObject(hSemaphore, 0); + --numToDecrease; + } + ReleaseMutex(hResultsMutex); + // 'q' can go out of scope if the user decides to close the serial port + // while processing some answer. So we need to guard against that. + QPointer<QWinOverlappedIoNotifier> qptr(q); + while (!values.empty() && qptr) { + IOResult ioresult = values.dequeue(); + emit qptr->notified(ioresult.numberOfBytes, ioresult.errorCode, ioresult.overlapped); + } + } } OVERLAPPED *QWinOverlappedIoNotifierPrivate::dispatchNextIoResult() |