perf: skip some excess announce list rebuilds

libtransmission/announce-list.h

@@ -92,6 +92,16 @@ public:
 
     [[nodiscard]] tr_tracker_tier_t nextTier() const;
 
+    [[nodiscard]] bool operator==(tr_announce_list const& that) const
+    {
+        return trackers_ == that.trackers_;
+    }
+
+    [[nodiscard]] bool operator!=(tr_announce_list const& that) const
+    {
+        return trackers_ != that.trackers_;
+    }
+
     bool add(std::string_view announce_url_sv)
     {
         return add(announce_url_sv, this->nextTier());

libtransmission/announcer.cc

@@ -581,8 +581,8 @@ private:
     {
         auto announce_list = tor->announceList();
 
-        // if it's a public torrent, inject the default trackers
-        if (!tor->isPrivate())
+        // if it's a public torrent, add the default trackers
+        if (tor->isPublic())
         {
             announce_list.add(tor->session->defaultTrackers());
         }

libtransmission/session.cc

@@ -2253,8 +2253,22 @@ int tr_sessionGetCacheLimit_MB(tr_session const* session)
 
 void tr_session::setDefaultTrackers(std::string_view trackers)
 {
-    this->default_trackers_str_ = trackers;
-    this->default_trackers_.parse(trackers);
+    auto const oldval = default_trackers_;
+
+    default_trackers_str_ = trackers;
+    default_trackers_.parse(trackers);
+
+    // if the list changed, update all the public torrents
+    if (default_trackers_ != oldval)
+    {
+        for (auto* tor : torrents)
+        {
+            if (tor->isPublic())
+            {
+                tr_announcerResetTorrent(announcer, tor);
+            }
+        }
+    }
 }
 
 void tr_sessionSetDefaultTrackers(tr_session* session, char const* trackers)

libtransmission/transmission.h

@@ -1195,7 +1195,7 @@ char* tr_torrentGetMagnetLink(tr_torrent const* tor);
  * along with tr_torrentSetTrackerList(), is intended for import/export
  * and user editing. It does *not* include the "default trackers" that
  * are applied to all public torrents. If you want a full display of all
- * trackers, use tr_torrentTracker() and tr_torrentTackerCount()
+ * trackers, use tr_torrentTracker() and tr_torrentTrackerCount()
  */
 char* tr_torrentGetTrackerList(tr_torrent const* tor);
 

qt/PrefsDialog.cc

@@ -25,6 +25,7 @@
 #include <QLabel>
 #include <QLineEdit>
 #include <QMessageBox>
+#include <QPlainTextEdit>
 #include <QPushButton>
 #include <QSpinBox>
 #include <QStyle>
@@ -239,12 +240,47 @@ void PrefsDialog::linkWidgetToPref(QWidget* widget, int pref_key)
         connect(spin_box, &QAbstractSpinBox::editingFinished, this, &PrefsDialog::spinBoxEditingFinished);
         return;
     }
+}
 
-    if (auto const* edit = qobject_cast<QPlainTextEdit*>(widget); edit != nullptr)
+static bool isDescendantOf(QObject const* descendant, QObject const* ancestor)
+{
+    if (ancestor == nullptr)
     {
-        connect(edit, &QPlainTextEdit::textChanged, this, &PrefsDialog::plainTextChanged);
-        return;
+        return false;
     }
+    while (descendant != nullptr)
+    {
+        if (descendant == ancestor)
+        {
+            return true;
+        }
+
+        descendant = descendant->parent();
+    }
+    return false;
+}
+
+void PrefsDialog::focusChanged(QWidget* old, QWidget* cur)
+{
+    // We don't want to change the preference every time there's a keystroke
+    // in a QPlainTextEdit, so instead of connecting to the textChanged signal,
+    // only update the pref when the text changed AND focus was lost.
+    char const constexpr* const StartValue = "StartValue";
+
+    if (auto* const edit = qobject_cast<QPlainTextEdit*>(cur); isDescendantOf(edit, this))
+    {
+        edit->setProperty(StartValue, edit->toPlainText());
+    }
+
+    if (auto const* const edit = qobject_cast<QPlainTextEdit*>(old); isDescendantOf(edit, this))
+    {
+        if (auto const val = edit->toPlainText(); val != edit->property(StartValue).toString())
+        {
+            setPref(PreferenceWidget{ old }.getPrefKey(), val);
+        }
+    }
+
+    // (TODO: we probably want to do this for single-line text entries too?)
 }
 
 void PrefsDialog::checkBoxToggled(bool checked)
@@ -306,22 +342,6 @@ void PrefsDialog::pathChanged(QString const& path)
     }
 }
 
-void PrefsDialog::plainTextChanged()
-{
-    PreferenceWidget const pref_widget(sender());
-
-    if (pref_widget.is<QPlainTextEdit>())
-    {
-        auto const* const plain_text_edit = pref_widget.as<QPlainTextEdit>();
-
-        if (plain_text_edit->document()->isModified())
-        {
-            prefs_.set(pref_widget.getPrefKey(), plain_text_edit->toPlainText());
-            // we avoid using setPref() because the included refreshPref() call would reset the cursor while we're editing
-        }
-    }
-}
-
 /***
 ****
 ***/
@@ -704,6 +724,8 @@ PrefsDialog::PrefsDialog(Session& session, Prefs& prefs, QWidget* parent)
     }
 
     adjustSize();
+
+    connect(qApp, &QApplication::focusChanged, this, &PrefsDialog::focusChanged);
 }
 
 void PrefsDialog::setPref(int key, QVariant const& v)

qt/PrefsDialog.h

@@ -29,12 +29,12 @@ public:
     PrefsDialog(Session&, Prefs&, QWidget* parent = nullptr);
 
 private slots:
+    void focusChanged(QWidget* old, QWidget* now);
     void checkBoxToggled(bool checked);
     void spinBoxEditingFinished();
     void timeEditingFinished();
     void lineEditingFinished();
     void pathChanged(QString const& path);
-    void plainTextChanged();
     void refreshPref(int key);
     void encryptionEdited(int);
     void altSpeedDaysEdited(int);