qautoresetevent_pipe.cpp

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// Copyright (C) 2024 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_pipe_p.h"
 
#include <QtCore/private/qcore_unix_p.h>
#include <QtCore/qdebug.h>
 
#include <unistd.h>
#include <cstdint>
 
QT_BEGIN_NAMESPACE
 
namespace QtPrivate {
 
QAutoResetEventPipe::QAutoResetEventPipe(QObject *parent)
    : QObject{
          parent,
      },
      m_notifier{
          QSocketNotifier::Type::Read,
          this,
      }
{
    int pipedes[2];
    int status = pipe(pipedes);
    if (status == -1) {
        qCritical() << "pipe failed:" << qt_error_string(errno);
        return;
    }
 
    m_fdConsumer.reset(pipedes[0]);
    m_fdProducer.reset(pipedes[1]);
 
    connect(&m_notifier, &QSocketNotifier::activated, this, [this] {
        QT_WARNING_PUSH
        QT_WARNING_DISABLE_GCC("-Wmaybe-uninitialized")
        std::array<char, 1024> buffer;
 
        qint64 bytesRead = qt_safe_read(m_fdConsumer.get(), buffer.data(), buffer.size());
        Q_ASSERT(bytesRead > 0);
 
        m_consumePending.clear();
        Q_EMIT activated();
        QT_WARNING_POP
    });
    m_notifier.setSocket(m_fdConsumer.get());
    m_notifier.setEnabled(true);
}
 
void QAutoResetEventPipe::set()
{
    Q_ASSERT(isValid());
 
    bool consumePending = m_consumePending.test_and_set();
    if (consumePending)
        return;
 
    constexpr uint8_t dummy{ 1 };
 
    qint64 bytesWritten = qt_safe_write(m_fdProducer.get(), &dummy, sizeof(dummy));
    if (bytesWritten == -1)
        qCritical("QAutoResetEvent::set failed");
}
 
} // namespace QtPrivate
 
QT_END_NAMESPACE
 
#include "moc_qautoresetevent_pipe_p.cpp"