refactor: use QDBusServiceWatcher to detect frontend exit

Replace polling-based frontend exit detection with event-driven
DBus NameOwnerChanged signal monitoring.

Changes:
- Use QDBusServiceWatcher to monitor frontend DBus name unregistration
- Remove QTimer-based /proc/<pid>/exe polling
- Simplify command-line arguments (remove PID, keep DBus name only)

Benefits:
- Event-driven instead of polling, more efficient
- No dependency on Linux-specific /proc filesystem
- More reliable detection via DBus daemon guarantees

Task: https://pms.uniontech.com/task-view-388685.html

Author: wangrong1069

application/main.cpp

@@ -156,7 +156,7 @@ int main(int argc, char *argv[])
         }
 
         QStringList argList;
-        argList << QString::number(QCoreApplication::applicationPid()) << QDBusConnection::systemBus().baseService();
+        argList << QDBusConnection::systemBus().baseService();
         qDebug() << "Starting deepin-diskmanager-authenticateProxy with args:" << argList;
         proc.startDetached("deepin-diskmanager-authenticateProxy", argList);
 

service/main.cpp

@@ -9,23 +9,12 @@
 #include <DLog>
 #include <QDBusConnection>
 #include <QDBusError>
+#include <QDBusServiceWatcher>
 #include <QThread>
 
 const QString DiskManagerServiceName = "com.deepin.diskmanager";
 const QString DiskManagerPath = "/com/deepin/diskmanager";
 
-void checkFrontEndQuit(uint frontEndPid)
-{
-    qDebug() << "checkFrontEndQuit" << frontEndPid;
-    QString frontEndExe = QString("/proc/%1/exe").arg(frontEndPid);
-    QFileInfo info(frontEndExe);
-
-    if (QFileInfo(info.symLinkTarget()).fileName() != "deepin-diskmanager") {
-        qWarning() << "Front-end process has quit";
-        QCoreApplication::exit(0);
-    }
-}
-
 int main(int argc, char *argv[])
 {
     //set env otherwise utils excutecmd  excute command failed
@@ -40,20 +29,17 @@ int main(int argc, char *argv[])
     PATH += ":/sbin";
     qputenv("PATH", PATH.toLatin1());
 
-    uint frontEndPid;
     QString frontEndDBusName;
-    if (argc < 3) {
+    if (argc < 2) {
         qCritical() << "Invalid arguments count:" << argc;
         return 1;
     } else {
         qDebug() << "Arguments count:" << argc;
-        QString frontEndPidString(argv[1]);
-        frontEndPid = frontEndPidString.toUInt();
-        if (frontEndPid == 0) {
-            qCritical() << "Invalid front-end PID:" << frontEndPid;
+        frontEndDBusName = QString(argv[1]);
+        if (frontEndDBusName.isEmpty()) {
+            qCritical() << "Invalid front-end DBus name";
             return 1;
         }
-        frontEndDBusName = QString(argv[2]);
     }
 
     QCoreApplication a(argc, argv);
@@ -96,11 +82,16 @@ int main(int argc, char *argv[])
         exit(0x0002);
     }
 
-    QTimer timer;
-    QObject::connect(&timer, &QTimer::timeout, [frontEndPid] {
-        checkFrontEndQuit(frontEndPid);
+    QDBusServiceWatcher *watcher = new QDBusServiceWatcher(
+        frontEndDBusName,
+        QDBusConnection::systemBus(),
+        QDBusServiceWatcher::WatchForUnregistration,
+        &a
+    );
+    QObject::connect(watcher, &QDBusServiceWatcher::serviceUnregistered, [](const QString &name) {
+        qWarning() << "Front-end service unregistered:" << name;
+        QCoreApplication::exit(0);
     });
-    timer.start(1000);
 
     return a.exec();
 }