Allow blocking auto files refresh

While importing assets, qml files are generated under the import
path and this triggers files update every time a file is added.
This results into high CPU usage.

Task-number: QDS-1675
Change-Id: Ia0775ef78bbffedfaf2c140365ee31718e7ee3a4
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmlprojectmanager/qmlproject.cpp

@@ -57,11 +57,16 @@
 #include <QDebug>
 #include <QRegularExpression>
 #include <QTextCodec>
+#include <QLoggingCategory>
 
 using namespace Core;
 using namespace ProjectExplorer;
 using namespace QmlProjectManager::Internal;
 
+namespace {
+Q_LOGGING_CATEGORY(infoLogger, "QmlProjectManager.QmlBuildSystem", QtInfoMsg)
+}
+
 namespace QmlProjectManager {
 
 QmlProject::QmlProject(const Utils::FilePath &fileName)
@@ -276,6 +281,10 @@ QStringList QmlBuildSystem::makeAbsolute(const Utils::FilePath &path, const QStr
 
 void QmlBuildSystem::refreshFiles(const QSet<QString> &/*added*/, const QSet<QString> &removed)
 {
+    if (m_blockFilesUpdate) {
+        qCDebug(infoLogger) << "Auto files refresh blocked.";
+        return;
+    }
     refresh(Files);
     if (!removed.isEmpty()) {
         if (auto modelManager = QmlJS::ModelManagerInterface::instance())

src/plugins/qmlprojectmanager/qmlproject.h

@@ -104,6 +104,27 @@ public:
 
     QPointer<QmlProjectItem> m_projectItem;
     Utils::FilePath m_canonicalProjectDir;
+
+private:
+    bool m_blockFilesUpdate = false;
+    friend class FilesUpdateBlocker;
+};
+
+class FilesUpdateBlocker {
+public:
+    FilesUpdateBlocker(QmlBuildSystem* bs): m_bs(bs) {
+        if (m_bs)
+            m_bs->m_blockFilesUpdate = true;
+    }
+
+    ~FilesUpdateBlocker() {
+        if (m_bs) {
+            m_bs->m_blockFilesUpdate = false;
+            m_bs->refresh(QmlBuildSystem::Everything);
+        }
+    }
+private:
+    QPointer<QmlBuildSystem> m_bs;
 };
 
 class QMLPROJECTMANAGER_EXPORT QmlProject : public ProjectExplorer::Project