Ensure all polling threads are dead before destroying hosts, even ones that have been detached by stopPollingAsync()

app/backend/computermanager.h

@@ -51,6 +51,79 @@ private:
     QMdnsEngine::Resolver m_Resolver;
 };
 
+class ComputerPollingEntry
+{
+public:
+    ComputerPollingEntry()
+        : m_ActiveThread(nullptr)
+    {
+
+    }
+
+    virtual ~ComputerPollingEntry()
+    {
+        interrupt();
+
+        // interrupt() should have taken care of this
+        Q_ASSERT(m_ActiveThread == nullptr);
+
+        for (QThread* thread : m_InactiveList) {
+            thread->wait();
+            delete thread;
+        }
+    }
+
+    bool isActive()
+    {
+        cleanInactiveList();
+
+        return m_ActiveThread != nullptr;
+    }
+
+    void setActiveThread(QThread* thread)
+    {
+        cleanInactiveList();
+
+        Q_ASSERT(!isActive());
+        m_ActiveThread = thread;
+    }
+
+    void interrupt()
+    {
+        cleanInactiveList();
+
+        if (m_ActiveThread != nullptr) {
+            // Interrupt the active thread
+            m_ActiveThread->requestInterruption();
+
+            // Place it on the inactive list awaiting death
+            m_InactiveList.append(m_ActiveThread);
+
+            m_ActiveThread = nullptr;
+        }
+    }
+
+private:
+    void cleanInactiveList()
+    {
+        QMutableListIterator<QThread*> i(m_InactiveList);
+
+        // Reap any threads that have finished
+        while (i.hasNext()) {
+            i.next();
+
+            QThread* thread = i.value();
+            if (thread->isFinished()) {
+                delete thread;
+                i.remove();
+            }
+        }
+    }
+
+    QThread* m_ActiveThread;
+    QList<QThread*> m_InactiveList;
+};
+
 class ComputerManager : public QObject
 {
     Q_OBJECT
@@ -100,7 +173,7 @@ private:
     int m_PollingRef;
     QReadWriteLock m_Lock;
     QMap<QString, NvComputer*> m_KnownHosts;
-    QMap<QString, QThread*> m_PollThreads;
+    QMap<QString, ComputerPollingEntry*> m_PollEntries;
     QMdnsEngine::Server m_MdnsServer;
     QMdnsEngine::Browser* m_MdnsBrowser;
     QMdnsEngine::Cache m_MdnsCache;