qautoresetevent_kqueue.cpp

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// Copyright (C) 2025 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 "qautoresetevent_kqueue_p.h"
 
#include <QtCore/private/qcore_unix_p.h>
#include <QtCore/qdebug.h>
 
QT_BEGIN_NAMESPACE
 
namespace QtPrivate {
 
QAutoResetEventKQueue::QAutoResetEventKQueue(QObject *parent):
    QObject{
        parent,
    },
    m_notifier{
        QSocketNotifier::Type::Read,
    }
{
    m_kqueue = kqueue();
    if (m_kqueue == -1) {
        qCritical() << "kqueue failed:" << qt_error_string(errno);
        return;
    }
 
    // Register a custom EVFILT_USER event with the EV_CLEAR flag.
    // The EV_CLEAR flag causes the event to auto-reset once it is delivered.
    EV_SET(&m_event, 1, EVFILT_USER, EV_ADD | EV_CLEAR, 0, 0, nullptr);
    if (kevent(m_kqueue, &m_event, 1, nullptr, 0, nullptr) == -1) {
        close(m_kqueue);
        qCritical() << "Failed to register EVFILT_USER event:" << qt_error_string(errno);
        return;
    }
 
    connect(&m_notifier, &QSocketNotifier::activated, this, [this] {
        struct kevent ev;
        int nev = kevent(m_kqueue, nullptr, 0, &ev, 1, nullptr);
        if (nev > 0)
            emit activated();
    });
    m_notifier.setSocket(m_kqueue);
    m_notifier.setEnabled(true);
}
 
QAutoResetEventKQueue::~QAutoResetEventKQueue()
{
    if (m_kqueue != -1)
        qt_safe_close(m_kqueue);
}
 
void QAutoResetEventKQueue::set()
{
    Q_ASSERT(isValid());
 
    EV_SET(&m_event, 1, EVFILT_USER, 0, NOTE_TRIGGER, 0, nullptr);
 
    if (kevent(m_kqueue, &m_event, 1, nullptr, 0, nullptr) == -1)
        qWarning() << "Failed to signal event";
}
 
bool QAutoResetEventKQueue::isValid() const
{
    return m_kqueue != -1;
}
 
} // namespace QtPrivate
 
QT_END_NAMESPACE
 
#include "moc_qautoresetevent_kqueue_p.cpp"