plugins: create ProcessControl plugin

This plugin is used to watch for applications requesting location
updates, and keep them awaken even when unfocused. In the future we
might listen for wake-up requests coming from other system processes.

Contributes to ubports/ubuntu-touch#1067

debian/unity8-private.install

@@ -6,6 +6,7 @@ usr/lib/*/unity8/qml/Greeter
 usr/lib/*/unity8/qml/LightDM
 usr/lib/*/unity8/qml/Lights
 usr/lib/*/unity8/qml/Powerd
+usr/lib/*/unity8/qml/ProcessControl
 usr/lib/*/unity8/qml/ScreenshotDirectory
 usr/lib/*/unity8/qml/SessionBroadcast
 usr/lib/*/unity8/qml/UInput

plugins/CMakeLists.txt

@@ -18,6 +18,7 @@ add_subdirectory(Greeter)
 add_subdirectory(LightDM)
 add_subdirectory(Lights)
 add_subdirectory(Powerd)
+add_subdirectory(ProcessControl)
 add_subdirectory(ScreenshotDirectory)
 add_subdirectory(SessionBroadcast)
 add_subdirectory(Ubuntu)

plugins/ProcessControl/CMakeLists.txt

@@ -0,0 +1,21 @@
+add_definitions(-DSM_BUSNAME=sessionBus)
+
+add_library(ProcessControl-qml MODULE
+    LocationWatcher.cpp
+    ProcessControl.cpp
+    plugin.cpp
+)
+
+target_link_libraries(ProcessControl-qml
+    Qt5::DBus Qt5::Qml
+)
+
+target_include_directories(ProcessControl-qml PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
+
+add_unity8_plugin(ProcessControl 0.1 ProcessControl TARGETS ProcessControl-qml)
+
+set(DBUS_IFACE_DIR "${CMAKE_INSTALL_PREFIX}/share/dbus-1/interfaces")
+
+install(FILES com.lomiri.ProcessControl.xml
+    DESTINATION "${DBUS_IFACE_DIR}"
+)

plugins/ProcessControl/LocationWatcher.cpp

@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2021 UBports Foundation.
+ *
+ * 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; version 3.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alberto Mardegan <mardy@users.sourceforge.net>
+ */
+
+#include "LocationWatcher.h"
+
+#include "ProcessControl.h"
+
+#include <QDBusConnection>
+#include <QDebug>
+#include <QStringList>
+#include <QTimer>
+
+namespace {
+const QString locationServiceName = QStringLiteral("com.ubuntu.location.Service");
+const QString locationObjectPath = QStringLiteral("/com/ubuntu/location/Service");
+const QString propertiesInterface = QStringLiteral("org.freedesktop.DBus.Properties");
+const QString methodPropertiesChanged = QStringLiteral("PropertiesChanged");
+} // namespace
+
+class LocationWatcherPrivate: public QObject
+{
+    Q_OBJECT
+
+public:
+    LocationWatcherPrivate(ProcessControl *processControl);
+
+private Q_SLOTS:
+    void onPropertiesChanged(const QString &interface,
+                             const QVariantMap &changedProps,
+                             const QStringList &invalidatedProps);
+
+private:
+    friend class LocationWatcher;
+    ProcessControl *m_processControl;
+    QDBusConnection m_connection;
+    QStringList m_clientApplications;
+};
+
+LocationWatcherPrivate::LocationWatcherPrivate(ProcessControl *processControl):
+    QObject(),
+    m_processControl(processControl),
+    m_connection(QDBusConnection::systemBus())
+{
+    m_connection.connect(locationServiceName,
+                         locationObjectPath,
+                         propertiesInterface,
+                         methodPropertiesChanged,
+                         this,
+                         SLOT(onPropertiesChanged(QString,QVariantMap,QStringList)));
+}
+
+void LocationWatcherPrivate::onPropertiesChanged(const QString &interface,
+                                                 const QVariantMap &changedProps,
+                                                 const QStringList &invalidatedProps)
+{
+    Q_UNUSED(interface);
+    Q_UNUSED(invalidatedProps);
+
+    qDebug() << Q_FUNC_INFO << changedProps;
+    const auto i = changedProps.find(QStringLiteral("ClientApplications"));
+    if (i != changedProps.end()) {
+        const QStringList appIds = i.value().toStringList();
+        qDebug() << "Location clients changed:" << appIds;
+        /* We need to strip off the version (app IDs are in the form
+         * "<publisher>_<app-name>_<version>") */
+        m_clientApplications.clear();
+        for (const QString &appId: appIds) {
+            QStringList parts = appId.split('_');
+            QString versionLessAppId = parts.mid(0, 2).join('_');
+            m_clientApplications.append(versionLessAppId);
+        }
+        m_processControl->setAwakenProcesses(m_clientApplications);
+    }
+}
+
+LocationWatcher::LocationWatcher(ProcessControl *processControl):
+    QObject(processControl),
+    d_ptr(new LocationWatcherPrivate(processControl))
+{
+}
+
+LocationWatcher::~LocationWatcher() = default;
+
+#include "LocationWatcher.moc"

plugins/ProcessControl/LocationWatcher.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 UBports Foundation.
+ *
+ * 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; version 3.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alberto Mardegan <mardy@users.sourceforge.net>
+ */
+
+#ifndef LOMIRI_LOCATIONWATCHER_H
+#define LOMIRI_LOCATIONWATCHER_H
+
+#include <QObject>
+#include <QScopedPointer>
+
+class ProcessControl;
+
+class LocationWatcherPrivate;
+class LocationWatcher: public QObject
+{
+    Q_OBJECT
+
+public:
+    explicit LocationWatcher(ProcessControl *processControl);
+    ~LocationWatcher();
+
+private:
+    Q_DECLARE_PRIVATE(LocationWatcher)
+    QScopedPointer<LocationWatcherPrivate> d_ptr;
+};
+
+#endif // LOMIRI_LOCATIONWATCHER_H

plugins/ProcessControl/ProcessControl.cpp

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2021 UBports Foundation.
+ *
+ * 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; version 3.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alberto Mardegan <mardy@users.sourceforge.net>
+ */
+
+#include "ProcessControl.h"
+
+#include <QDebug>
+
+class ProcessControlPrivate
+{
+public:
+    ProcessControlPrivate(ProcessControl *q);
+
+private:
+    friend class ProcessControl;
+    QStringList m_awakenProcesses;
+};
+
+ProcessControlPrivate::ProcessControlPrivate(ProcessControl *q)
+{
+}
+
+ProcessControl::ProcessControl(QObject* parent):
+    QObject(parent),
+    d_ptr(new ProcessControlPrivate(this))
+{
+}
+
+ProcessControl::~ProcessControl() = default;
+
+void ProcessControl::setAwakenProcesses(const QStringList &processes)
+{
+    Q_D(ProcessControl);
+    d->m_awakenProcesses = processes;
+    Q_EMIT awakenProcessesChanged();
+}
+
+QStringList ProcessControl::awakenProcesses() const
+{
+    Q_D(const ProcessControl);
+    return d->m_awakenProcesses;
+}

plugins/ProcessControl/ProcessControl.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2021 UBports Foundation.
+ *
+ * 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; version 3.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alberto Mardegan <mardy@users.sourceforge.net>
+ */
+
+#ifndef LOMIRI_PROCESSCONTROL_H
+#define LOMIRI_PROCESSCONTROL_H
+
+#include <QObject>
+#include <QScopedPointer>
+#include <QStringList>
+
+class ProcessControlPrivate;
+class ProcessControl: public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(QStringList awakenProcesses READ awakenProcesses
+               NOTIFY awakenProcessesChanged)
+
+public:
+    explicit ProcessControl(QObject *parent = 0);
+    ~ProcessControl();
+
+    void setAwakenProcesses(const QStringList &processes);
+    QStringList awakenProcesses() const;
+
+Q_SIGNALS:
+    void awakenProcessesChanged();
+
+private:
+    Q_DECLARE_PRIVATE(ProcessControl)
+    QScopedPointer<ProcessControlPrivate> d_ptr;
+};
+
+#endif // LOMIRI_PROCESSCONTROL_H

plugins/ProcessControl/com.lomiri.ProcessControl.xml

@@ -0,0 +1,41 @@
+<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
+"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
+<node xmlns:doc="http://www.freedesktop.org/dbus/1.0/doc.dtd">
+  <!--
+    This is an interface meant to be accessible only from privileged system
+    processes.
+
+    It can be used to request Lomiri to alter the normal lifecycle of selected
+    applications, typically by granting them more wake-up times than they'd
+    normally have. For example, a location daemon could request a temporary
+    wake-up of its clients so that they'd be able to process the location
+    updates.
+  -->
+  <interface name="com.lomiri.ProcessControl">
+
+    <!--
+      Request a temporary wake-up of the selected processes.
+
+      Whether the request will actually be fulfilled is up to Lomiri.
+
+      This method will not return an error reply if a process listed in the
+      `processes` argument is not found.
+    -->
+    <method name="RequestWakeup">
+      <!--
+        The list of processes to be waken-up. Each process is specified by its
+        application ID (appId).
+      -->
+      <arg name="processes" direction="in" type="as" />
+
+      <!--
+        The desired time span that should be granted to each of the
+        applications, in milliseconds.
+      -->
+      <arg name="timeSpan" direction="in" type="t" />
+
+      <annotation name="org.freedesktop.DBus.Method.NoReply" value="true"/>
+    </method>
+
+  </interface>
+</node>

plugins/ProcessControl/plugin.cpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 UBports Foundation.
+ *
+ * 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; version 3.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alberto Mardegan <mardy@users.sourceforge.net>
+ */
+
+#include "plugin.h"
+
+#include "LocationWatcher.h"
+#include "ProcessControl.h"
+
+#include <QQmlEngine>
+
+static QObject *service_provider(QQmlEngine *engine, QJSEngine *scriptEngine)
+{
+    Q_UNUSED(engine);
+    Q_UNUSED(scriptEngine);
+
+    ProcessControl *processControl = new ProcessControl();
+    new LocationWatcher(processControl);
+
+    return processControl;
+}
+
+void ProcessControlPlugin::registerTypes(const char *uri)
+{
+    Q_ASSERT(uri == QLatin1String("ProcessControl"));
+    qmlRegisterSingletonType<ProcessControl>(uri, 0, 1, "ProcessControl", service_provider);
+}