Locator: Avoid use of QtConcurrent

QtConcurrent limits resource usage to a global number of simultaneous
threads. That means that if some QtConcurrent based algorithm currently
grabs all threads, any other use of QtConcurrent blocks, which is not
what we want.
Use the new threading methods of C++11 instead, but still use
QFuture(Interface) manually for status reporting.

Task-number: QTCREATORBUG-14640
Change-Id: I8fecb43b5235da92c0d239e7dd5f2c108ab32ebf
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/libs/utils/runextensions.h

@@ -520,6 +520,16 @@ void blockingMapReduce(QFutureInterface<ReduceResult> futureInterface, const Con
     futureInterface.reportFinished();
 }
 
+template <typename ResultType, typename Function, typename... Args>
+void runAsyncImpl(QFutureInterface<ResultType> futureInterface, const Function &function, const Args&... args)
+{
+    futureInterface.reportStarted();
+    function(futureInterface, args...);
+    if (futureInterface.isPaused())
+        futureInterface.waitForResume();
+    futureInterface.reportFinished();
+}
+
 } // Internal
 
 template <typename ReduceResult, typename Container, typename InitFunction, typename MapFunction,
@@ -547,6 +557,15 @@ QFuture<ReduceResult> mapReduce(const Container &container, const InitFunction &
     return future;
 }
 
+template <typename ResultType, typename Function, typename... Args>
+QFuture<ResultType> runAsync(Function &&function, Args&&... args)
+{
+    QFutureInterface<ResultType> futureInterface;
+    std::thread(Internal::runAsyncImpl<ResultType,Function,Args...>, futureInterface,
+                std::forward<Function>(function), std::forward<Args>(args)...).detach();
+    return futureInterface.future();
+}
+
 } // Utils
 
 #endif // RUNEXTENSIONS_H

src/plugins/coreplugin/locator/locatorfiltertest.cpp

@@ -51,8 +51,9 @@ QList<LocatorFilterEntry> BasicLocatorFilterTest::matchesFor(const QString &sear
     doBeforeLocatorRun();
     const QList<ILocatorFilter *> filters = QList<ILocatorFilter *>() << m_filter;
     m_filter->prepareSearch(searchText);
-    QFuture<LocatorFilterEntry> locatorSearch = QtConcurrent::run(Internal::runSearch,
-                                                           filters, searchText);
+    QFuture<LocatorFilterEntry> locatorSearch = Utils::runAsync<LocatorFilterEntry>(&Internal::runSearch,
+                                                                                    filters,
+                                                                                    searchText);
     locatorSearch.waitForFinished();
     doAfterLocatorRun();
     return locatorSearch.results();

src/plugins/coreplugin/locator/locatorsearchutils.cpp

@@ -47,7 +47,7 @@ uint qHash(const LocatorFilterEntry &entry)
 } // namespace Core
 
 void Core::Internal::runSearch(QFutureInterface<Core::LocatorFilterEntry> &future,
-                                  QList<ILocatorFilter *> filters, QString searchText)
+                               const QList<ILocatorFilter *> &filters, const QString &searchText)
 {
     QSet<LocatorFilterEntry> alreadyAdded;
     const bool checkDuplicates = (filters.size() > 1);

src/plugins/coreplugin/locator/locatorsearchutils.h

@@ -37,8 +37,8 @@ namespace Core {
 namespace Internal {
 
 void CORE_EXPORT runSearch(QFutureInterface<LocatorFilterEntry> &future,
-                              QList<ILocatorFilter *> filters,
-                              QString searchText);
+                              const QList<ILocatorFilter *> &filters,
+                              const QString &searchText);
 
 } // namespace Internal
 } // namespace Core

src/plugins/coreplugin/locator/locatorwidget.cpp

@@ -524,7 +524,8 @@ void LocatorWidget::updateCompletionList(const QString &text)
 
     foreach (ILocatorFilter *filter, filters)
         filter->prepareSearch(searchText);
-    QFuture<LocatorFilterEntry> future = QtConcurrent::run(runSearch, filters, searchText);
+    QFuture<LocatorFilterEntry> future = Utils::runAsync<LocatorFilterEntry>(&runSearch, filters,
+                                                                             QString(searchText));
     m_entriesWatcher->setFuture(future);
 }