From ef988cc8afce9a8c1e13344fb7e00cd909f79558 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Wed, 21 Jun 2023 00:51:31 -0500
Subject: [PATCH] Destroy the QMdnsEngine Server and Cache when not polling

These set background timers to refresh state, rebind sockets,
and refresh the cache. This is all stuff that we don't want to
be doing while streaming.
---
 app/backend/computermanager.cpp |  8 +++++---
 app/backend/computermanager.h   | 25 +++++++++++++++++++------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/app/backend/computermanager.cpp b/app/backend/computermanager.cpp
index 9c519d87..4f447502 100644
--- a/app/backend/computermanager.cpp
+++ b/app/backend/computermanager.cpp
@@ -319,12 +319,13 @@ void ComputerManager::startPolling()
 
     if (prefs.enableMdns) {
         // Start an MDNS query for GameStream hosts
-        m_MdnsBrowser = new QMdnsEngine::Browser(&m_MdnsServer, "_nvstream._tcp.local.", &m_MdnsCache);
+        m_MdnsServer.reset(new QMdnsEngine::Server());
+        m_MdnsBrowser = new QMdnsEngine::Browser(m_MdnsServer.get(), "_nvstream._tcp.local.");
         connect(m_MdnsBrowser, &QMdnsEngine::Browser::serviceAdded,
                 this, [this](const QMdnsEngine::Service& service) {
             qInfo() << "Discovered mDNS host:" << service.hostname();
 
-            MdnsPendingComputer* pendingComputer = new MdnsPendingComputer(&m_MdnsServer, service);
+            MdnsPendingComputer* pendingComputer = new MdnsPendingComputer(m_MdnsServer, service);
             connect(pendingComputer, &MdnsPendingComputer::resolvedHost,
                     this, &ComputerManager::handleMdnsServiceResolved);
             m_PendingResolution.append(pendingComputer);
@@ -646,9 +647,10 @@ void ComputerManager::stopPollingAsync()
         m_PendingResolution.removeFirst();
     }
 
-    // Delete the browser to stop discovery
+    // Delete the browser and server to stop discovery and refresh polling
     delete m_MdnsBrowser;
     m_MdnsBrowser = nullptr;
+    m_MdnsServer.reset();
 
     // Interrupt all threads, but don't wait for them to terminate
     for (ComputerPollingEntry* entry : m_PollEntries) {
diff --git a/app/backend/computermanager.h b/app/backend/computermanager.h
index b8f45f40..011e094f 100644
--- a/app/backend/computermanager.h
+++ b/app/backend/computermanager.h
@@ -42,11 +42,11 @@ class MdnsPendingComputer : public QObject
     Q_OBJECT
 
 public:
-    explicit MdnsPendingComputer(QMdnsEngine::Server* server,
+    explicit MdnsPendingComputer(const QSharedPointer<QMdnsEngine::Server> server,
                                  const QMdnsEngine::Service& service)
         : m_Hostname(service.hostname()),
           m_Port(service.port()),
-          m_Server(server),
+          m_ServerWeak(server),
           m_Resolver(nullptr)
     {
         // Start resolving
@@ -94,8 +94,21 @@ signals:
 private:
     void resolve()
     {
+        // Delete our resolver, so we're guaranteed that nothing is referencing m_Server.
         delete m_Resolver;
-        m_Resolver = new QMdnsEngine::Resolver(m_Server, m_Hostname);
+        m_Resolver = nullptr;
+
+        // Now delete our strong reference that we held on behalf of m_Resolver.
+        // The server may be destroyed after we make this call.
+        m_Server.reset();
+
+        // Re-acquire a strong reference if the server still exists.
+        m_Server = m_ServerWeak.toStrongRef();
+        if (!m_Server) {
+            return;
+        }
+
+        m_Resolver = new QMdnsEngine::Resolver(m_Server.get(), m_Hostname);
         connect(m_Resolver, &QMdnsEngine::Resolver::resolved,
                 this, &MdnsPendingComputer::handleResolvedAddress);
         QTimer::singleShot(2000, this, &MdnsPendingComputer::handleResolvedTimeout);
@@ -103,7 +116,8 @@ private:
 
     QByteArray m_Hostname;
     uint16_t m_Port;
-    QMdnsEngine::Server* m_Server;
+    QWeakPointer<QMdnsEngine::Server> m_ServerWeak;
+    QSharedPointer<QMdnsEngine::Server> m_Server;
     QMdnsEngine::Resolver* m_Resolver;
     QVector<QHostAddress> m_Addresses;
 };
@@ -245,9 +259,8 @@ private:
     QReadWriteLock m_Lock;
     QMap<QString, NvComputer*> m_KnownHosts;
     QMap<QString, ComputerPollingEntry*> m_PollEntries;
-    QMdnsEngine::Server m_MdnsServer;
+    QSharedPointer<QMdnsEngine::Server> m_MdnsServer;
     QMdnsEngine::Browser* m_MdnsBrowser;
-    QMdnsEngine::Cache m_MdnsCache;
     QVector<MdnsPendingComputer*> m_PendingResolution;
     CompatFetcher m_CompatFetcher;
     DelayedFlushThread* m_DelayedFlushThread;