gui, spline-widget, compat/options: ensure no qsettings IO when not modified

Turns out every MainWindow::save() and friends were doing useless IO
several times during each save. I blame the bundle abstraction.

For bundles we track the modified state, but the spline widget needs
equality check since it doesn't use the options api.

It was found by accident when adding qDebug() into the slider_value
{de,}serializer code. The .ini file was being rewritten over and over
again causing hundres of milliseconds pauses on Windows.

Remove the save timer kludge from gui. Saves are now fast.

1 files changed, 21 insertions, 11 deletions

diff --git a/opentrack-compat/options.cpp b/opentrack-compat/options.cpp
index 55a4b795..785698de 100644
--- a/opentrack-compat/options.cpp
+++ b/opentrack-compat/options.cpp
@@ -88,7 +88,7 @@ const mem<QSettings> group::ini_file()
     return std::make_shared<QSettings>();
 }
 
-impl_bundle::impl_bundle(const QString &group_name)
+impl_bundle::impl_bundle(const QString& group_name)
     :
       mtx(QMutex::Recursive),
       group_name(group_name),
@@ -101,20 +101,25 @@ void impl_bundle::reload()
 {
     {
         QMutexLocker l(&mtx);
-        saved = group(group_name);
-        transient = saved;
-        modified = false;
+        if (modified)
+        {
+            saved = group(group_name);
+            transient = saved;
+            modified = false;
+        }
     }
     emit reloading();
 }
 
-void impl_bundle::store_kv(const QString &name, const QVariant &datum)
+void impl_bundle::store_kv(const QString& name, const QVariant& datum)
 {
     QMutexLocker l(&mtx);
 
     auto old = transient.get<QVariant>(name);
     if (!transient.contains(name) || datum != old)
     {
+        if (!modified)
+            qDebug() << "bundle" << group_name << "modified" << "key" << name << "to" << datum << "from" << old;
         modified = true;
         transient.put(name, datum);
     }
@@ -128,13 +133,20 @@ bool impl_bundle::contains(const QString &name) const
 
 void impl_bundle::save()
 {
+    bool modified_ = false;
     {
         QMutexLocker l(&mtx);
-        modified = false;
-        saved = transient;
-        transient.save();
+        if (modified)
+        {
+            qDebug() << "bundle" << group_name << "saved";
+            modified_ = true;
+            modified = false;
+            saved = transient;
+            transient.save();
+        }
     }
-    emit saving();
+    if (modified_)
+        emit saving();
 }
 
 bool impl_bundle::modifiedp() const
@@ -220,7 +232,6 @@ custom_type_initializer custom_type_initializer::singleton = custom_type_initial
 QDataStream& operator <<(QDataStream& out, const options::slider_value& v)
 {
     out << v.cur() << v.min() << v.max();
-    qDebug() << "out cur" << v.cur();
     return out;
 }
 
@@ -231,6 +242,5 @@ QDataStream& operator >>(QDataStream& in, options::slider_value& v)
     in >> min;
     in >> max;
     v = options::slider_value(cur, min, max);
-    qDebug() << "in cur" << v.cur();
     return in;
 }