QMakeProjectManager: Reduce priority of parsing threads.

Task-number: QTCREATORBUG-14640
Change-Id: I32b47888ecf3627bc21649a0c922216fb9e714a6
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

2 files changed, 26 insertions, 1 deletions

diff --git a/src/libs/utils/runextensions.h b/src/libs/utils/runextensions.h
index 7427dbfb13..433ac523a9 100644
--- a/src/libs/utils/runextensions.h
+++ b/src/libs/utils/runextensions.h
@@ -28,6 +28,7 @@
 
 #include "qtcassert.h"
 
+#include <QCoreApplication>
 #include <QFuture>
 #include <QFutureInterface>
 #include <QRunnable>
@@ -581,6 +582,10 @@ public:
 
     void run() override
     {
+        if (priority != QThread::InheritPriority)
+            if (QThread *thread = QThread::currentThread())
+                if (thread != qApp->thread())
+                    thread->setPriority(priority);
         if (futureInterface.isCanceled()) {
             futureInterface.reportFinished();
             return;
@@ -593,6 +598,11 @@ public:
         futureInterface.setThreadPool(pool);
     }
 
+    void setThreadPriority(QThread::Priority p)
+    {
+        priority = p;
+    }
+
 private:
     using Data = std::tuple<typename std::decay<Function>::type, typename std::decay<Args>::type...>;
 
@@ -605,6 +615,7 @@ private:
 
     Data data;
     QFutureInterface<ResultType> futureInterface;
+    QThread::Priority priority = QThread::InheritPriority;
 };
 
 } // Internal
@@ -662,16 +673,29 @@ QFuture<ResultType> runAsync(Function &&function, Args&&... args)
 }
 
 template <typename ResultType, typename Function, typename... Args>
-QFuture<ResultType> runAsync(QThreadPool *pool, Function &&function, Args&&... args)
+QFuture<ResultType> runAsync(QThreadPool *pool, QThread::Priority priority,
+                             Function &&function, Args&&... args)
 {
     auto job = new Internal::AsyncJob<ResultType,Function,Args...>
             (std::forward<Function>(function), std::forward<Args>(args)...);
     job->setThreadPool(pool);
+    job->setThreadPriority(priority);
     QFuture<ResultType> future = job->future();
     pool->start(job);
     return future;
 }
 
+template <typename ResultType, typename Function, typename... Args,
+          typename = typename std::enable_if<
+                !std::is_same<typename std::decay<Function>::type, QThread::Priority>::value
+              >::type>
+QFuture<ResultType> runAsync(QThreadPool *pool,
+                             Function &&function, Args&&... args)
+{
+    return runAsync<ResultType>(pool, QThread::InheritPriority, std::forward<Function>(function),
+                                std::forward<Args>(args)...);
+}
+
 } // Utils
 
 #endif // RUNEXTENSIONS_H
diff --git a/src/plugins/qmakeprojectmanager/qmakenodes.cpp b/src/plugins/qmakeprojectmanager/qmakenodes.cpp
index 2808a6dd60..350f57fc2a 100644
--- a/src/plugins/qmakeprojectmanager/qmakenodes.cpp
+++ b/src/plugins/qmakeprojectmanager/qmakenodes.cpp
@@ -1801,6 +1801,7 @@ void QmakeProFileNode::asyncUpdate()
     m_parseFutureWatcher.waitForFinished();
     EvalInput input = evalInput();
     QFuture<EvalResult *> future = Utils::runAsync<EvalResult *>(ProjectExplorerPlugin::sharedThreadPool(),
+                                                                 QThread::LowestPriority,
                                                                  &QmakeProFileNode::asyncEvaluate,
                                                                  this, input);
     m_parseFutureWatcher.setFuture(future);