Avoid blocking call when changing libtorrent session settings

We don't really need to get currently used settings pack in order to apply changes to session settings. It is enough to apply settings pack that contains only updated settings.

PR #17989.

src/base/bittorrent/portforwarderimpl.cpp

@@ -107,10 +107,10 @@ void PortForwarderImpl::removePorts(const QString &profile)
 
 void PortForwarderImpl::start()
 {
-    lt::settings_pack settingsPack = m_provider->get_settings();
+    lt::settings_pack settingsPack;
     settingsPack.set_bool(lt::settings_pack::enable_upnp, true);
     settingsPack.set_bool(lt::settings_pack::enable_natpmp, true);
-    m_provider->apply_settings(settingsPack);
+    m_provider->apply_settings(std::move(settingsPack));
 
     for (auto profileIter = m_portProfiles.begin(); profileIter != m_portProfiles.end(); ++profileIter)
     {
@@ -129,10 +129,10 @@ void PortForwarderImpl::start()
 
 void PortForwarderImpl::stop()
 {
-    lt::settings_pack settingsPack = m_provider->get_settings();
+    lt::settings_pack settingsPack;
     settingsPack.set_bool(lt::settings_pack::enable_upnp, false);
     settingsPack.set_bool(lt::settings_pack::enable_natpmp, false);
-    m_provider->apply_settings(settingsPack);
+    m_provider->apply_settings(std::move(settingsPack));
 
     // don't clear m_portProfiles so a later `start()` call can restore the port forwardings
     for (auto profileIter = m_portProfiles.begin(); profileIter != m_portProfiles.end(); ++profileIter)

src/base/bittorrent/sessionimpl.cpp

@@ -1066,25 +1066,25 @@ void SessionImpl::adjustLimits()
 {
     if (isQueueingSystemEnabled())
     {
-        lt::settings_pack settingsPack = m_nativeSession->get_settings();
+        lt::settings_pack settingsPack;
-        adjustLimits(settingsPack);
+        // Internally increase the queue limits to ensure that the magnet is started
-        m_nativeSession->apply_settings(settingsPack);
+        settingsPack.set_int(lt::settings_pack::active_downloads, adjustLimit(maxActiveDownloads()));
+        settingsPack.set_int(lt::settings_pack::active_limit, adjustLimit(maxActiveTorrents()));
+        m_nativeSession->apply_settings(std::move(settingsPack));
     }
 }
 
 void SessionImpl::applyBandwidthLimits()
 {
-    lt::settings_pack settingsPack = m_nativeSession->get_settings();
+    lt::settings_pack settingsPack;
-    applyBandwidthLimits(settingsPack);
+    settingsPack.set_int(lt::settings_pack::download_rate_limit, downloadSpeedLimit());
-    m_nativeSession->apply_settings(settingsPack);
+    settingsPack.set_int(lt::settings_pack::upload_rate_limit, uploadSpeedLimit());
+    m_nativeSession->apply_settings(std::move(settingsPack));
 }
 
 void SessionImpl::configure()
 {
-    lt::settings_pack settingsPack = m_nativeSession->get_settings();
+    m_nativeSession->apply_settings(loadLTSettings());
-    loadLTSettings(settingsPack);
-    m_nativeSession->apply_settings(settingsPack);
-
     configureComponents();
 
     m_deferredConfigureScheduled = false;
@@ -1430,10 +1430,11 @@ void SessionImpl::endStartup(ResumeSessionContext *context)
 
 void SessionImpl::initializeNativeSession()
 {
-    const std::string peerId = lt::generate_fingerprint(PEER_ID, QBT_VERSION_MAJOR, QBT_VERSION_MINOR, QBT_VERSION_BUGFIX, QBT_VERSION_BUILD);
+    lt::settings_pack pack = loadLTSettings();
 
-    lt::settings_pack pack;
+    const std::string peerId = lt::generate_fingerprint(PEER_ID, QBT_VERSION_MAJOR, QBT_VERSION_MINOR, QBT_VERSION_BUGFIX, QBT_VERSION_BUILD);
     pack.set_str(lt::settings_pack::peer_fingerprint, peerId);
+
     pack.set_bool(lt::settings_pack::listen_system_port_fallback, false);
     pack.set_str(lt::settings_pack::user_agent, USER_AGENT.toStdString());
     pack.set_bool(lt::settings_pack::use_dht_as_fallback, false);
@@ -1450,8 +1451,7 @@ void SessionImpl::initializeNativeSession()
     pack.set_bool(lt::settings_pack::enable_set_file_valid_data, true);
 #endif
 
-    loadLTSettings(pack);
+    lt::session_params sessionParams {std::move(pack), {}};
-    lt::session_params sessionParams {pack, {}};
 #ifdef QBT_USES_LIBTORRENT2
     switch (diskIOType())
     {
@@ -1509,28 +1509,14 @@ void SessionImpl::processBannedIPs(lt::ip_filter &filter)
     }
 }
 
-void SessionImpl::adjustLimits(lt::settings_pack &settingsPack) const
+int SessionImpl::adjustLimit(const int limit) const
 {
-    // Internally increase the queue limits to ensure that the magnet is started
+    if (limit <= -1)
-    const auto adjustLimit = [this](const int limit) -> int
+        return limit;
-    {
+    // check for overflow: (limit + m_extraLimit) < std::numeric_limits<int>::max()
-        if (limit <= -1)
+    return (m_extraLimit < (std::numeric_limits<int>::max() - limit))
-            return limit;
+        ? (limit + m_extraLimit)
-        // check for overflow: (limit + m_extraLimit) < std::numeric_limits<int>::max()
+        : std::numeric_limits<int>::max();
-        return (m_extraLimit < (std::numeric_limits<int>::max() - limit))
-            ? (limit + m_extraLimit)
-            : std::numeric_limits<int>::max();
-    };
-
-    settingsPack.set_int(lt::settings_pack::active_downloads, adjustLimit(maxActiveDownloads()));
-    settingsPack.set_int(lt::settings_pack::active_limit, adjustLimit(maxActiveTorrents()));
-}
-
-void SessionImpl::applyBandwidthLimits(lt::settings_pack &settingsPack) const
-{
-    const bool altSpeedLimitEnabled = isAltGlobalSpeedLimitEnabled();
-    settingsPack.set_int(lt::settings_pack::download_rate_limit, altSpeedLimitEnabled ? altGlobalDownloadSpeedLimit() : globalDownloadSpeedLimit());
-    settingsPack.set_int(lt::settings_pack::upload_rate_limit, altSpeedLimitEnabled ? altGlobalUploadSpeedLimit() : globalUploadSpeedLimit());
 }
 
 void SessionImpl::initMetrics()
@@ -1575,8 +1561,10 @@ void SessionImpl::initMetrics()
     m_metricIndices.disk.diskJobTime = findMetricIndex("disk.disk_job_time");
 }
 
-void SessionImpl::loadLTSettings(lt::settings_pack &settingsPack)
+lt::settings_pack SessionImpl::loadLTSettings() const
 {
+    lt::settings_pack settingsPack;
+
     const lt::alert_category_t alertMask = lt::alert::error_notification
         | lt::alert::file_progress_notification
         | lt::alert::ip_block_notification
@@ -1594,8 +1582,10 @@ void SessionImpl::loadLTSettings(lt::settings_pack &settingsPack)
     // It will not take affect until the listen_interfaces settings is updated
     settingsPack.set_int(lt::settings_pack::listen_queue_size, socketBacklogSize());
 
-    configureNetworkInterfaces(settingsPack);
+    applyNetworkInterfacesSettings(settingsPack);
-    applyBandwidthLimits(settingsPack);
+
+    settingsPack.set_int(lt::settings_pack::download_rate_limit, downloadSpeedLimit());
+    settingsPack.set_int(lt::settings_pack::upload_rate_limit, uploadSpeedLimit());
 
     // The most secure, rc4 only so that all streams are encrypted
     settingsPack.set_int(lt::settings_pack::allowed_enc_level, lt::settings_pack::pe_rc4);
@@ -1730,7 +1720,9 @@ void SessionImpl::loadLTSettings(lt::settings_pack &settingsPack)
     // Queueing System
     if (isQueueingSystemEnabled())
     {
-        adjustLimits(settingsPack);
+        // Internally increase the queue limits to ensure that the magnet is started
+        settingsPack.set_int(lt::settings_pack::active_downloads, adjustLimit(maxActiveDownloads()));
+        settingsPack.set_int(lt::settings_pack::active_limit, adjustLimit(maxActiveTorrents()));
 
         settingsPack.set_int(lt::settings_pack::active_seeds, maxActiveUploads());
         settingsPack.set_bool(lt::settings_pack::dont_count_slow_torrents, ignoreSlowTorrentsForQueueing());
@@ -1846,9 +1838,11 @@ void SessionImpl::loadLTSettings(lt::settings_pack &settingsPack)
         settingsPack.set_int(lt::settings_pack::seed_choking_algorithm, lt::settings_pack::anti_leech);
         break;
     }
+
+    return settingsPack;
 }
 
-void SessionImpl::configureNetworkInterfaces(lt::settings_pack &settingsPack)
+void SessionImpl::applyNetworkInterfacesSettings(lt::settings_pack &settingsPack) const
 {
     if (m_listenInterfaceConfigured)
         return;

src/base/bittorrent/sessionimpl.h

@@ -474,11 +474,10 @@ namespace BitTorrent
         Q_INVOKABLE void configure();
         void configureComponents();
         void initializeNativeSession();
-        void loadLTSettings(lt::settings_pack &settingsPack);
+        lt::settings_pack loadLTSettings() const;
-        void configureNetworkInterfaces(lt::settings_pack &settingsPack);
+        void applyNetworkInterfacesSettings(lt::settings_pack &settingsPack) const;
         void configurePeerClasses();
-        void adjustLimits(lt::settings_pack &settingsPack) const;
+        int adjustLimit(int limit) const;
-        void applyBandwidthLimits(lt::settings_pack &settingsPack) const;
         void initMetrics();
         void adjustLimits();
         void applyBandwidthLimits();
@@ -553,7 +552,7 @@ namespace BitTorrent
 
         bool m_deferredConfigureScheduled = false;
         bool m_IPFilteringConfigured = false;
-        bool m_listenInterfaceConfigured = false;
+        mutable bool m_listenInterfaceConfigured = false;
 
         CachedSettingValue<bool> m_isDHTEnabled;
         CachedSettingValue<bool> m_isLSDEnabled;