CppProjectUpdater: Wait for all tasks to be finished in d'tor

It may happen that the old task was canceled and still running
while the new task was started. Later, when the d'tor is called
both old and new tasks may still be running. Before we waited only
for the new task to be finished in d'tor. Now we are waiting
for all tasks to be finished.

Amends: 7fb592fe0c

Task-number: QTCREATORBUG-25709
Change-Id: Id4b44cd36ee03aa45472b15d8fbb25a2cab77e92
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/cpptools/cppprojectupdater.cpp

@@ -43,11 +43,7 @@ CppProjectUpdater::CppProjectUpdater()
             &QFutureWatcher<ProjectInfo>::finished,
             this,
             &CppProjectUpdater::onProjectInfoGenerated);
-}
+    m_futureSynchronizer.setCancelOnWait(true);
-
-CppProjectUpdater::~CppProjectUpdater()
-{
-    cancelAndWaitForFinished();
 }
 
 void CppProjectUpdater::update(const ProjectExplorer::ProjectUpdateInfo &projectUpdateInfo)
@@ -63,30 +59,21 @@ void CppProjectUpdater::update(const ProjectExplorer::ProjectUpdateInfo &project
             this, &CppProjectUpdater::onToolChainRemoved);
 
     // Run the project info generator in a worker thread and continue if that one is finished.
-    m_generateFuture = Utils::runAsync([=](QFutureInterface<ProjectInfo> &futureInterface) {
+    auto generateFuture = Utils::runAsync([=](QFutureInterface<ProjectInfo> &futureInterface) {
         ProjectUpdateInfo fullProjectUpdateInfo = projectUpdateInfo;
         if (fullProjectUpdateInfo.rppGenerator)
             fullProjectUpdateInfo.rawProjectParts = fullProjectUpdateInfo.rppGenerator();
         Internal::ProjectInfoGenerator generator(futureInterface, fullProjectUpdateInfo);
         futureInterface.reportResult(generator.generate());
     });
-    m_generateFutureWatcher.setFuture(m_generateFuture);
+    m_generateFutureWatcher.setFuture(generateFuture);
+    m_futureSynchronizer.addFuture(generateFuture);
 }
 
 void CppProjectUpdater::cancel()
 {
     m_generateFutureWatcher.setFuture({});
-    m_generateFuture.cancel();
+    m_futureSynchronizer.cancelAllFutures();
-    m_updateFuture.cancel();
-}
-
-void CppProjectUpdater::cancelAndWaitForFinished()
-{
-    cancel();
-    if (m_generateFuture.isRunning())
-        m_generateFuture.waitForFinished();
-    if (m_updateFuture.isRunning())
-        m_updateFuture.waitForFinished();
 }
 
 void CppProjectUpdater::onToolChainRemoved(ProjectExplorer::ToolChain *t)
@@ -106,8 +93,9 @@ void CppProjectUpdater::onProjectInfoGenerated()
     if (m_generateFutureWatcher.isCanceled() || m_generateFutureWatcher.future().resultCount() < 1)
         return;
 
-    m_updateFuture = CppModelManager::instance()->updateProjectInfo(
+    auto updateFuture = CppModelManager::instance()->updateProjectInfo(
         m_generateFutureWatcher.result());
+    m_futureSynchronizer.addFuture(updateFuture);
 }
 
 CppProjectUpdaterFactory::CppProjectUpdaterFactory()

src/plugins/cpptools/cppprojectupdater.h

@@ -29,6 +29,8 @@
 #include "cpptools_global.h"
 #include "projectinfo.h"
 
+#include <utils/futuresynchronizer.h>
+
 #include <QFutureWatcher>
 
 namespace CppTools {
@@ -52,23 +54,19 @@ class CPPTOOLS_EXPORT CppProjectUpdater final : public QObject, public CppProjec
 
 public:
     CppProjectUpdater();
-    ~CppProjectUpdater() override;
 
     void update(const ProjectExplorer::ProjectUpdateInfo &projectUpdateInfo) override;
     void cancel() override;
 
 private:
-    void cancelAndWaitForFinished();
-
     void onToolChainRemoved(ProjectExplorer::ToolChain *);
     void onProjectInfoGenerated();
 
 private:
     ProjectExplorer::ProjectUpdateInfo m_projectUpdateInfo;
 
-    QFuture<ProjectInfo> m_generateFuture;
-    QFuture<void> m_updateFuture;
     QFutureWatcher<ProjectInfo> m_generateFutureWatcher;
+    Utils::FutureSynchronizer m_futureSynchronizer;
 };
 
 } // namespace CppTools