- Including Watchdog Timer in CoreBackendManager to ping DBus service.

- Including ExternalCommandHelper::ping slot to receive pings.
- Including timer to watch last ping in the service to unregister it after reaching 42 seconds without pings.

src/backend/corebackendmanager.cpp

@@ -25,6 +25,7 @@
 #include <QDBusInterface>
 #include <QStringList>
 #include <QString>
+#include <QTimer>
 #include <QVector>
 #include <QUuid>
 
@@ -78,6 +79,22 @@ void CoreBackendManager::startExternalCommandHelper()
     auto conn = QObject::connect(job(), &KAuth::ExecuteJob::newData, exitLoop);
     loop.exec();
     QObject::disconnect(conn);
+
+    // Watchdog Timer for the DBus service
+    QTimer *timer = new QTimer;
+
+    auto sendDBusPing = [&] () {
+        QDBusInterface iface(QStringLiteral("org.kde.kpmcore.helperinterface"),
+                             QStringLiteral("/Helper"),
+                             QStringLiteral("org.kde.kpmcore.externalcommand"),
+                             QDBusConnection::systemBus());
+
+        if (iface.isValid())
+            iface.call(QStringLiteral("ping"), CoreBackendManager::self()->Uuid());
+    };
+
+    QObject::connect(timer, &QTimer::timeout, sendDBusPing);
+    timer->start(20000); // 20 seconds
 }
 
 void CoreBackendManager::stopExternalCommandHelper()

src/util/externalcommandhelper.cpp

@@ -17,6 +17,7 @@
 
 #include "externalcommandhelper.h"
 
+#include <QDate>
 #include <QtDBus>
 #include <QDBusContext>
 #include <QDebug>
@@ -49,6 +50,13 @@ ActionReply ExternalCommandHelper::init(const QVariantMap& args)
     HelperSupport::progressStep(QVariantMap());
     m_loop.exec();
     reply.addData(QStringLiteral("success"), true);
+
+    m_pingTime = new QDateTime(QDateTime::currentDateTime());
+
+    QTimer *timer = new QTimer(this);
+    connect(timer, &QTimer::timeout, this, &ExternalCommandHelper::checkPing);
+    timer->start(20000); // check ping every 20 secs
+
     return reply;
 }
 
@@ -237,6 +245,29 @@ void ExternalCommandHelper::exit(const QString& Uuid)
     QDBusConnection::systemBus().unregisterObject(QStringLiteral("/Helper"));
 }
 
+void ExternalCommandHelper::ping(const QString &Uuid)
+{
+    if (!isCallerAuthorized(Uuid))
+        return;
+
+    // update ping
+    m_pingTime->setDate(QDate::currentDate());
+    m_pingTime->setTime(QTime::currentTime());
+}
+
+void ExternalCommandHelper::checkPing()
+{
+    qint64 mSecsSinceLastPing = m_pingTime->msecsTo(QDateTime::currentDateTime());
+
+    qDebug() << (((double)mSecsSinceLastPing) / 1000) << " seconds since the last ping.";
+
+    if (mSecsSinceLastPing >= 42000) { // more than 42 seconds since the last ping
+        qDebug() << "Ending DBus service";
+
+        exit(m_callerUuid);
+    }
+}
+
 void ExternalCommandHelper::onReadOutput()
 {
 //     const QByteArray s = cmd.readAllStandardOutput();

src/util/externalcommandhelper.h

@@ -20,6 +20,7 @@
 
 #include <KAuth>
 
+#include <QDateTime>
 #include <QEventLoop>
 #include <QString>
 #include <QProcess>
@@ -44,6 +45,10 @@ public Q_SLOTS:
     Q_SCRIPTABLE QVariantMap start(const QString& Uuid, const QString& command, const QStringList& arguments, const QByteArray& input, const QStringList& environment);
     Q_SCRIPTABLE bool copyblocks(const QString& Uuid, const QString& sourceDevice, const qint64 sourceFirstByte, const qint64 sourceLength, const QString& targetDevice, const qint64 targetFirstByte, const qint64 blockSize);
     Q_SCRIPTABLE void exit(const QString& Uuid);
+    Q_SCRIPTABLE void ping(const QString& Uuid);
+
+private Q_SLOTS:
+    void checkPing();
 
 private:
     void onReadOutput();
@@ -54,6 +59,8 @@ private:
     QString m_command;
     QString m_sourceDevice;
     QProcess m_cmd;
+
+    QDateTime *m_pingTime;
 //     QByteArray output;
 };