优化本地配置文件的写入性能

1. 因为文件IO是不靠谱的和不稳定的，所以，将本地文件的同步写入放到独立的
线程中，不再依赖于主线程，避免IO出现问题导致UI卡顿

2. 只有当上一次写入操作结束之后才会进行下一次写入操作，确保新的数据始终
能够正确覆盖旧的数据

kylin-virtual-keyboard.pro

@@ -1,4 +1,5 @@
 QT += quick
+QT += concurrent
 QT += dbus
 QT += core gui
 QT += KWindowSystem

src/localsettings/viewlocalsettings.cpp

@@ -1,14 +1,54 @@
 #include "viewlocalsettings.h"
 
+#include <QSettings>
+#include <QtConcurrent>
+
+namespace {
+void updateSettings(QSettings &settings,
+                    const ViewLocalSettings::SettingMap &settingMap) {
+    for (auto settingIter = settingMap.constBegin();
+         settingIter != settingMap.constEnd(); settingIter++) {
+        settings.setValue(settingIter.key(), settingIter.value());
+    }
+}
+
+void saveSettings(const QString &organization, const QString &application,
+                  const ViewLocalSettings::GroupSettingMap &groupSettingMap) {
+    QSettings settings(organization, application);
+
+    for (auto groupIter = groupSettingMap.constBegin();
+         groupIter != groupSettingMap.constEnd(); groupIter++) {
+        settings.beginGroup(groupIter.key());
+
+        updateSettings(settings, groupIter.value());
+
+        settings.endGroup();
+    }
+
+    settings.sync();
+}
+} // namespace
+
 ViewLocalSettings::ViewLocalSettings(const QString &organization,
                                      const QString &application)
-    : settings(organization, application) {}
+    : organization_(organization), application_(application) {
+    QObject::connect(&futureWatcher_, &QFutureWatcher<void>::finished,
+                     [this]() {
+                         if (groupSettingMap_.isEmpty()) {
+                             return;
+                         }
+
+                         saveSettingsAsync();
+                     });
+}
 
 ViewLocalSettings::~ViewLocalSettings() = default;
 
 QVariant
 ViewLocalSettings::getValue(const QString &group, const QString &key,
                             const QVariant &defaultValue /*= QVariant()*/) {
+    QSettings settings(organization_, application_);
+
     settings.beginGroup(group);
 
     auto value = settings.value(key, defaultValue);
@@ -20,9 +60,18 @@ ViewLocalSettings::getValue(const QString &group, const QString &key,
 
 void ViewLocalSettings::setValue(const QString &group, const QString &key,
                                  const QVariant &value) {
-    settings.beginGroup(group);
+    auto &settingMap = groupSettingMap_[group];
+    settingMap.insert(key, value);
 
-    settings.setValue(key, value);
-
-    settings.endGroup();
+    if (futureWatcher_.isFinished()) {
+        saveSettingsAsync();
+    }
+}
+
+void ViewLocalSettings::saveSettingsAsync() {
+    auto oneshotGroupSettingMap(std::move(groupSettingMap_));
+    futureWatcher_.setFuture(
+        QtConcurrent::run([this, oneshotGroupSettingMap]() {
+            saveSettings(organization_, application_, oneshotGroupSettingMap);
+        }));
 }

src/localsettings/viewlocalsettings.h

@@ -1,11 +1,16 @@
 #ifndef VIEWLOCALSETTINGS_H
 #define VIEWLOCALSETTINGS_H
 
-#include <QSettings>
+#include <QFutureWatcher>
+#include <QMap>
 
 #include "localsettings.h"
 
 class ViewLocalSettings : public LocalSettings {
+public:
+    using SettingMap = QMap<QString, QVariant>;
+    using GroupSettingMap = QMap<QString, SettingMap>;
+
 public:
     ViewLocalSettings(const QString &organization, const QString &application);
     ~ViewLocalSettings() override;
@@ -16,7 +21,14 @@ public:
                   const QVariant &value) override;
 
 private:
-    QSettings settings;
+    void saveSettingsAsync();
+
+private:
+    const QString organization_;
+    const QString application_;
+
+    GroupSettingMap groupSettingMap_;
+    QFutureWatcher<void> futureWatcher_;
 };
 
 #endif // VIEWLOCALSETTINGS_H