kwin/src/ftrace.h

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/*
KWin - the KDE window manager
This file is part of the KDE project.
SPDX-FileCopyrightText: 2021 David Edmundson <davidedmundson@kde.org>
SPDX-License-Identifier: LGPL-2.0-or-later
*/
#pragma once
#include <kwinglobals.h>
#include <QFile>
#include <QMutex>
#include <QMutexLocker>
#include <QObject>
#include <QTextStream>
namespace KWin
{
/**
* FTraceLogger is a singleton utility for writing log messages using ftrace
*
* Usage: Either:
* Set the KWIN_PERF_FTRACE environment variable before starting the application
* Calling on DBus /FTrace org.kde.kwin.FTrace.setEnabled true
* After having created the ftrace mount
*/
class KWIN_EXPORT FTraceLogger : public QObject
{
Q_OBJECT
Q_CLASSINFO("D-Bus Interface", "org.kde.kwin.FTrace");
Q_PROPERTY(bool isEnabled READ isEnabled NOTIFY enabledChanged)
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public:
/**
* Enabled through DBus and logging has started
*/
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bool isEnabled() const;
/**
* Main log function
* Takes any number of arguments that can be written into QTextStream
*/
template<typename... Args> void trace(Args... args)
{
Q_ASSERT(isEnabled());
QMutexLocker lock(&m_mutex);
if (!m_file.isOpen()) {
return;
}
QTextStream stream(&m_file);
(stream << ... << args) << Qt::endl;
}
Q_SIGNALS:
void enabledChanged();
public Q_SLOTS:
Q_SCRIPTABLE void setEnabled(bool enabled);
private:
static QString filePath();
bool open();
QFile m_file;
QMutex m_mutex;
KWIN_SINGLETON(FTraceLogger)
};
class KWIN_EXPORT FTraceDuration
{
public:
template<typename... Args> FTraceDuration(Args... args)
{
static QAtomicInteger<quint32> s_context = 0;
QTextStream stream(&m_message);
(stream << ... << args);
stream.flush();
m_context = ++s_context;
FTraceLogger::self()->trace(m_message, " begin_ctx=", m_context);
}
~FTraceDuration();
private:
QByteArray m_message;
quint32 m_context;
};
} // namespace KWin
/**
* Optimised macro, arguments are only copied if tracing is enabled
*/
#define fTrace(...) \
if (KWin::FTraceLogger::self()->isEnabled()) \
KWin::FTraceLogger::self()->trace(__VA_ARGS__);
/**
* Will insert two markers into the log. Once when called, and the second at the end of the relevant block
* In GPUVis this will appear as a timed block with begin_ctx and end_ctx markers
*/
#define fTraceDuration(...) \
QScopedPointer<KWin::FTraceDuration> _duration(KWin::FTraceLogger::self()->isEnabled() ? new KWin::FTraceDuration(__VA_ARGS__) : nullptr);