From 03b73243252fbbf3ba7ae3831a45b96397ecc935 Mon Sep 17 00:00:00 2001
From: Jarek Kobus <jaroslaw.kobus@qt.io>
Date: Wed, 26 May 2021 09:06:06 +0200
Subject: [PATCH] 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: 7fb592fe0cfec22ae7e966b9c6b88aa801bf9592

Task-number: QTCREATORBUG-25709
Change-Id: Id4b44cd36ee03aa45472b15d8fbb25a2cab77e92
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
---
 src/plugins/cpptools/cppprojectupdater.cpp | 26 ++++++----------------
 src/plugins/cpptools/cppprojectupdater.h   |  8 +++----
 2 files changed, 10 insertions(+), 24 deletions(-)

diff --git a/src/plugins/cpptools/cppprojectupdater.cpp b/src/plugins/cpptools/cppprojectupdater.cpp
index 567aabde5ee..794fd7abe7f 100644
--- a/src/plugins/cpptools/cppprojectupdater.cpp
+++ b/src/plugins/cpptools/cppprojectupdater.cpp
@@ -43,11 +43,7 @@ CppProjectUpdater::CppProjectUpdater()
             &QFutureWatcher<ProjectInfo>::finished,
             this,
             &CppProjectUpdater::onProjectInfoGenerated);
-}
-
-CppProjectUpdater::~CppProjectUpdater()
-{
-    cancelAndWaitForFinished();
+    m_futureSynchronizer.setCancelOnWait(true);
 }
 
 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_updateFuture.cancel();
-}
-
-void CppProjectUpdater::cancelAndWaitForFinished()
-{
-    cancel();
-    if (m_generateFuture.isRunning())
-        m_generateFuture.waitForFinished();
-    if (m_updateFuture.isRunning())
-        m_updateFuture.waitForFinished();
+    m_futureSynchronizer.cancelAllFutures();
 }
 
 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()
diff --git a/src/plugins/cpptools/cppprojectupdater.h b/src/plugins/cpptools/cppprojectupdater.h
index f3f85a8a14f..6b994871ef9 100644
--- a/src/plugins/cpptools/cppprojectupdater.h
+++ b/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