refs #545 CSetting<T>::setAndSave to set and save a setting in one step.

src/blackcore/contextapplicationimpl.cpp

@@ -22,7 +22,9 @@ namespace BlackCore
 {
     CContextApplication::CContextApplication(CRuntimeConfig::ContextMode mode, CRuntime *runtime) :
         IContextApplication(mode, runtime)
-    {}
+    {
+        connect(CSettingsCache::instance(), &CSettingsCache::valuesSaveRequested, CSettingsCache::instance(), &CSettingsCache::saveToStoreByPacket);
+    }
 
     CContextApplication *CContextApplication::registerWithDBus(BlackMisc::CDBusServer *server)
     {

src/blackmisc/datacache.h

@@ -148,6 +148,9 @@ namespace BlackMisc
 
         //! Deleted copy assignment operator.
         CDataTrait &operator =(const CDataTrait &) = delete;
+
+        //! Data cache doesn't support setAndSave (because set() already causes save anyway).
+        CStatusMessage setAndSave(const T &value) = delete;
     };
 }
 

src/blackmisc/settingscache.cpp

@@ -8,6 +8,7 @@
  */
 
 #include "settingscache.h"
+#include "logmessage.h"
 #include <QStandardPaths>
 
 namespace BlackMisc
@@ -33,6 +34,15 @@ namespace BlackMisc
         return saveToFiles(persistentStore(), keyPrefix);
     }
 
+    void CSettingsCache::saveToStoreByPacket(const CValueCachePacket &values)
+    {
+        CStatusMessage status = saveToFiles(persistentStore(), values.toVariantMap());
+        if (! status.isEmpty())
+        {
+            CLogMessage(this).preformatted(status);
+        }
+    }
+
     BlackMisc::CStatusMessage CSettingsCache::loadFromStore()
     {
         return loadFromFiles(persistentStore());

src/blackmisc/settingscache.h

@@ -34,6 +34,10 @@ namespace BlackMisc
         //! Save core settings to disk.
         BlackMisc::CStatusMessage saveToStore(const QString &keyPrefix = {});
 
+        //! Save individual settings to disk.
+        //! Core application context connects this slot to the valuesSaveRequested signal.
+        void saveToStoreByPacket(const CValueCachePacket &values);
+
         //! Load core settings from disk.
         BlackMisc::CStatusMessage loadFromStore();
 

src/blackmisc/valuecache.cpp

@@ -168,7 +168,7 @@ namespace BlackMisc
     {
         QMutexLocker lock(&m_mutex);
         if (values.empty()) { return; }
-        CValueCachePacket ratifiedChanges;
+        CValueCachePacket ratifiedChanges(values.isSaved());
         auto out = m_elements.lowerBound(values.cbegin().key());
         auto end = m_elements.upperBound((values.cend() - 1).key());
         for (auto in = values.cbegin(); in != values.cend(); ++in)
@@ -191,6 +191,7 @@ namespace BlackMisc
         }
         if (! ratifiedChanges.empty())
         {
+            if (ratifiedChanges.isSaved()) { emit valuesSaveRequested(ratifiedChanges); }
             emit valuesChanged(ratifiedChanges, nullptr);
         }
     }
@@ -395,7 +396,7 @@ namespace BlackMisc
         return element.m_value.read();
     }
 
-    CStatusMessage CValuePage::setValue(Element &element, const CVariant &value)
+    CStatusMessage CValuePage::setValue(Element &element, const CVariant &value, bool save)
     {
         Q_ASSERT(QThread::currentThread() == thread());
 
@@ -412,10 +413,10 @@ namespace BlackMisc
             {
                 Q_ASSERT(isSafeToIncrement(element.m_pendingChanges));
                 element.m_pendingChanges++;
-                element.m_saved = false;
+                element.m_saved = save;
 
                 element.m_value.uniqueWrite() = value;
-                emit valuesWantToCache({ { { element.m_key, value } }, QDateTime::currentMSecsSinceEpoch() });
+                emit valuesWantToCache({ { { element.m_key, value } }, QDateTime::currentMSecsSinceEpoch(), save });
             }
         }
         else

src/blackmisc/valuecache.h

@@ -180,6 +180,10 @@ namespace BlackMisc
         //! of CValueCache instances in all processes including this one. The slot will do its own round-trip detection.
         void valuesChangedByLocal(const BlackMisc::CValueCachePacket &values);
 
+        //! Emitted when this cache has ratified a change which included a request to save (i.e. via CCaches::setAndSave).
+        //! If the derived class does not handle such requests, the signal can be ignored.
+        void valuesSaveRequested(const BlackMisc::CValueCachePacket &values);
+
     private:
         struct Element; // remove forward declaration when elementsStartingWith uses C++14 auto deduced return type
 
@@ -274,6 +278,9 @@ namespace BlackMisc
         //! Write a new value. Must be called from the thread in which the owner lives.
         CStatusMessage set(const T &value) { return m_page.setValue(m_element, CVariant::from(value)); }
 
+        //! Write and save in the same step. Must be called from the thread in which the owner lives.
+        CStatusMessage setAndSave(const T &value) { return m_page.setValue(m_element, CVariant::from(value), true); }
+
         //! Get the key string of this value.
         const QString &getKey() const { return m_page.getKey(m_element); }
 

src/blackmisc/valuecacheprivate.h

@@ -62,7 +62,7 @@ namespace BlackMisc
             const CVariant &getValue(const Element &element) const;
 
             //! Write the value corresponding to the element's key and begin synchronizing it to any other pages.
-            CStatusMessage setValue(Element &element, const CVariant &value);
+            CStatusMessage setValue(Element &element, const CVariant &value, bool save = false);
 
             //! Get the key string corresponding to the element.
             const QString &getKey(const Element &element) const;