[nightcolor] Use a dedicated class for detection of system clock changes

Summary:
The ClockSkewNotifier provides a convenient way for monitoring system
clock changes. One of the key ideas was to hide platform details from
users of the class. This allows us to add a QTimer fallback path for
operating systems that don't provide anything to detect system clock
changes.

In long term, I would like to move the new class to Frameworks.

Reviewers: #kwin, davidedmundson

Reviewed By: #kwin, davidedmundson

Subscribers: davidedmundson, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D25962

CMakeLists.txt

@@ -401,6 +401,8 @@ set(kwin_KDEINIT_SRCS
     appmenu.cpp
     atoms.cpp
     client_machine.cpp
+    colorcorrection/clockskewnotifier.cpp
+    colorcorrection/clockskewnotifierengine.cpp
     colorcorrection/colorcorrectdbusinterface.cpp
     colorcorrection/manager.cpp
     colorcorrection/suncalc.cpp
@@ -502,6 +504,13 @@ set(kwin_KDEINIT_SRCS
     xwl/xwayland_interface.cpp
 )
 
+if (CMAKE_SYSTEM_NAME MATCHES "Linux")
+    set(kwin_KDEINIT_SRCS
+        ${kwin_KDEINIT_SRCS}
+        colorcorrection/clockskewnotifierengine_linux.cpp
+    )
+endif()
+
 include(ECMQtDeclareLoggingCategory)
 ecm_qt_declare_logging_category(kwin_KDEINIT_SRCS
     HEADER

colorcorrection/clockskewnotifier.cpp

@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2019 Vlad Zahorodnii <vladzzag@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "clockskewnotifier.h"
+#include "clockskewnotifierengine_p.h"
+
+namespace KWin
+{
+
+class ClockSkewNotifier::Private
+{
+public:
+    void loadNotifierEngine();
+    void unloadNotifierEngine();
+
+    ClockSkewNotifier *notifier = nullptr;
+    ClockSkewNotifierEngine *engine = nullptr;
+    bool isActive = false;
+};
+
+void ClockSkewNotifier::Private::loadNotifierEngine()
+{
+    engine = ClockSkewNotifierEngine::create(notifier);
+
+    if (engine) {
+        QObject::connect(engine, &ClockSkewNotifierEngine::clockSkewed, notifier, &ClockSkewNotifier::clockSkewed);
+    }
+}
+
+void ClockSkewNotifier::Private::unloadNotifierEngine()
+{
+    if (!engine) {
+        return;
+    }
+
+    QObject::disconnect(engine, &ClockSkewNotifierEngine::clockSkewed, notifier, &ClockSkewNotifier::clockSkewed);
+    engine->deleteLater();
+
+    engine = nullptr;
+}
+
+ClockSkewNotifier::ClockSkewNotifier(QObject *parent)
+    : QObject(parent)
+    , d(new Private)
+{
+    d->notifier = this;
+}
+
+ClockSkewNotifier::~ClockSkewNotifier()
+{
+}
+
+bool ClockSkewNotifier::isActive() const
+{
+    return d->isActive;
+}
+
+void ClockSkewNotifier::setActive(bool set)
+{
+    if (d->isActive == set) {
+        return;
+    }
+
+    d->isActive = set;
+
+    if (d->isActive) {
+        d->loadNotifierEngine();
+    } else {
+        d->unloadNotifierEngine();
+    }
+
+    emit activeChanged();
+}
+
+} // namespace KWin

colorcorrection/clockskewnotifier.h

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2019 Vlad Zahorodnii <vladzzag@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include <QObject>
+
+namespace KWin
+{
+
+/**
+ * The ClockSkewNotifier class provides a way for monitoring system clock changes.
+ *
+ * The ClockSkewNotifier class makes it possible to detect discontinuous changes to
+ * the system clock. Such changes are usually initiated by the user adjusting values
+ * in the Date and Time KCM or calls made to functions like settimeofday().
+ */
+class ClockSkewNotifier : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(bool active READ isActive WRITE setActive NOTIFY activeChanged)
+
+public:
+    explicit ClockSkewNotifier(QObject *parent = nullptr);
+    ~ClockSkewNotifier() override;
+
+    /**
+     * Returns @c true if the notifier is active; otherwise returns @c false.
+     */
+    bool isActive() const;
+
+    /**
+     * Sets the active status of the clock skew notifier to @p active.
+     *
+     * clockSkewed() signal won't be emitted while the notifier is inactive.
+     *
+     * The notifier is inactive by default.
+     *
+     * @see activeChanged
+     */
+    void setActive(bool active);
+
+signals:
+    /**
+     * This signal is emitted whenever the active property is changed.
+     */
+    void activeChanged();
+
+    /**
+     * This signal is emitted whenever the system clock is changed.
+     */
+    void clockSkewed();
+
+private:
+    class Private;
+    QScopedPointer<Private> d;
+};
+
+} // namespace KWin

colorcorrection/clockskewnotifierengine.cpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2019 Vlad Zahorodnii <vladzzag@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "clockskewnotifierengine_p.h"
+#if defined(Q_OS_LINUX)
+#include "clockskewnotifierengine_linux.h"
+#endif
+
+namespace KWin
+{
+
+ClockSkewNotifierEngine *ClockSkewNotifierEngine::create(QObject *parent)
+{
+#if defined(Q_OS_LINUX)
+    return LinuxClockSkewNotifierEngine::create(parent);
+#else
+    return nullptr;
+#endif
+}
+
+ClockSkewNotifierEngine::ClockSkewNotifierEngine(QObject *parent)
+    : QObject(parent)
+{
+}
+
+} // namespace KWin

colorcorrection/clockskewnotifierengine_linux.cpp

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2019 Vlad Zahorodnii <vladzzag@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "clockskewnotifierengine_linux.h"
+
+#include <QSocketNotifier>
+
+#include <fcntl.h>
+#include <sys/timerfd.h>
+#include <unistd.h>
+
+namespace KWin
+{
+
+LinuxClockSkewNotifierEngine *LinuxClockSkewNotifierEngine::create(QObject *parent)
+{
+    const int fd = timerfd_create(CLOCK_REALTIME, O_CLOEXEC | O_NONBLOCK);
+    if (fd == -1) {
+        qWarning("Couldn't create clock skew notifier engine: %s", strerror(errno));
+        return nullptr;
+    }
+
+    const itimerspec spec = {};
+    const int ret = timerfd_settime(fd, TFD_TIMER_ABSTIME | TFD_TIMER_CANCEL_ON_SET, &spec, nullptr);
+    if (ret == -1) {
+        qWarning("Couldn't create clock skew notifier engine: %s", strerror(errno));
+        close(fd);
+        return nullptr;
+    }
+
+    return new LinuxClockSkewNotifierEngine(fd, parent);
+}
+
+LinuxClockSkewNotifierEngine::LinuxClockSkewNotifierEngine(int fd, QObject *parent)
+    : ClockSkewNotifierEngine(parent)
+    , m_fd(fd)
+{
+    const QSocketNotifier *notifier = new QSocketNotifier(fd, QSocketNotifier::Read, this);
+    connect(notifier, &QSocketNotifier::activated, this, &LinuxClockSkewNotifierEngine::handleTimerCancelled);
+}
+
+LinuxClockSkewNotifierEngine::~LinuxClockSkewNotifierEngine()
+{
+    close(m_fd);
+}
+
+void LinuxClockSkewNotifierEngine::handleTimerCancelled()
+{
+    uint64_t expirationCount;
+    read(m_fd, &expirationCount, sizeof(expirationCount));
+
+    emit clockSkewed();
+}
+
+} // namespace KWin

colorcorrection/clockskewnotifierengine_linux.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2019 Vlad Zahorodnii <vladzzag@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include "clockskewnotifierengine_p.h"
+
+namespace KWin
+{
+
+class LinuxClockSkewNotifierEngine : public ClockSkewNotifierEngine
+{
+    Q_OBJECT
+
+public:
+    ~LinuxClockSkewNotifierEngine() override;
+
+    static LinuxClockSkewNotifierEngine *create(QObject *parent);
+
+private Q_SLOTS:
+    void handleTimerCancelled();
+
+private:
+    LinuxClockSkewNotifierEngine(int fd, QObject *parent);
+
+    int m_fd;
+};
+
+} // namespace KWin

colorcorrection/clockskewnotifierengine_p.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2019 Vlad Zahorodnii <vladzzag@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include <QObject>
+
+namespace KWin
+{
+
+class ClockSkewNotifierEngine : public QObject
+{
+    Q_OBJECT
+
+public:
+    static ClockSkewNotifierEngine *create(QObject *parent);
+
+protected:
+    explicit ClockSkewNotifierEngine(QObject *parent);
+
+Q_SIGNALS:
+    void clockSkewed();
+};
+
+} // namespace KWin

colorcorrection/manager.cpp

@@ -18,6 +18,7 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 #include "manager.h"
+#include "clockskewnotifier.h"
 #include "colorcorrectdbusinterface.h"
 #include "suncalc.h"
 #include <colorcorrect_logging.h>
@@ -36,15 +37,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <QAction>
 #include <QDBusConnection>
-#include <QSocketNotifier>
 #include <QTimer>
 
-#ifdef Q_OS_LINUX
-#include <sys/timerfd.h>
-#endif
-#include <unistd.h>
-#include <fcntl.h>
-
 namespace KWin {
 namespace ColorCorrect {
 
@@ -60,6 +54,8 @@ Manager::Manager(QObject *parent)
     : QObject(parent)
 {
     m_iface = new ColorCorrectDBusInterface(this);
+    m_skewNotifier = new ClockSkewNotifier(this);
+
     connect(kwinApp(), &Application::workspaceCreated, this, &Manager::init);
 
     // Display a message when Night Color is (un)inhibited.
@@ -106,26 +102,7 @@ void Manager::init()
             }
     );
 
-#ifdef Q_OS_LINUX
-    // monitor for system clock changes - from the time dataengine
-    auto timeChangedFd = ::timerfd_create(CLOCK_REALTIME, O_CLOEXEC | O_NONBLOCK);
-    ::itimerspec timespec;
-    //set all timers to 0, which creates a timer that won't do anything
-    ::memset(&timespec, 0, sizeof(timespec));
-
-    // Monitor for the time changing (flags == TFD_TIMER_ABSTIME | TFD_TIMER_CANCEL_ON_SET).
-    // However these are not exposed in glibc so value is hardcoded:
-    ::timerfd_settime(timeChangedFd, 3, &timespec, nullptr);
-
-    connect(this, &QObject::destroyed, [timeChangedFd]() {
-        ::close(timeChangedFd);
-    });
-
-    auto notifier = new QSocketNotifier(timeChangedFd, QSocketNotifier::Read, this);
-    connect(notifier, &QSocketNotifier::activated, this, [this](int fd) {
-        uint64_t c;
-        ::read(fd, &c, 8);
-
+    connect(m_skewNotifier, &ClockSkewNotifier::clockSkewed, this, [this]() {
         // check if we're resuming from suspend - in this case do a hard reset
         // Note: We're using the time clock to detect a suspend phase instead of connecting to the
         //       provided logind dbus signal, because this signal would be received way too late.
@@ -150,9 +127,6 @@ void Manager::init()
             resetAllTimers();
         }
     });
-#else
-    // TODO: Alternative method for BSD.
-#endif
 
     hardReset();
 }
@@ -914,6 +888,7 @@ void Manager::setEnabled(bool enabled)
         return;
     }
     m_active = enabled;
+    m_skewNotifier->setActive(enabled);
     emit enabledChanged();
 }
 

colorcorrection/manager.h

@@ -32,6 +32,7 @@ class QTimer;
 namespace KWin
 {
 
+class ClockSkewNotifier;
 class Workspace;
 
 namespace ColorCorrect
@@ -245,6 +246,7 @@ private:
     void setMode(NightColorMode mode);
 
     ColorCorrectDBusInterface *m_iface;
+    ClockSkewNotifier *m_skewNotifier;
 
     // Specifies whether Night Color is enabled.
     bool m_active;