ProjectExplorer: Rework the build step run interface

Originally, the build manager used to run all build steps in a dedicated
thread. Communication between the step and the manager happened via a
QFutureInterface that was passed into the step's run() function.
Later, new steps were added that operated asynchronously, so the build
manager had to differentiate between the different kinds of steps for
starting and stopping.
These days, almost all build and deploy steps work asynchronously, which
made the QFuture-based interface look increasingly odd.
With this patch, all build steps are expected to work asynchronously, so
the build manager no longer needs to differentiate. Steps are started
and requested to stop via the run() and cancel() functions,
respectively, and emit the finished() signal when they are done. Build
step implementors no longer have to deal with a QFutureInterface. For
steps whose implementation is inherently synchronous, the BuildStep base
class offers a runInThread() function.

Change-Id: If905c68b234c5a669f6e19f43142eaa57d594803
Reviewed-by: hjk <hjk@qt.io>

1 files changed, 19 insertions, 51 deletions

diff --git a/src/plugins/projectexplorer/buildmanager.cpp b/src/plugins/projectexplorer/buildmanager.cpp
index 68fe6f1356..544677517a 100644
--- a/src/plugins/projectexplorer/buildmanager.cpp
+++ b/src/plugins/projectexplorer/buildmanager.cpp
@@ -79,9 +79,8 @@ public:
     // is set to true while canceling, so that nextBuildStep knows that the BuildStep finished because of canceling
     bool m_skipDisabled = false;
     bool m_canceling = false;
-    QFutureWatcher<bool> m_watcher;
-    QFutureInterface<bool> m_futureInterfaceForAysnc;
-    BuildStep *m_currentBuildStep;
+    bool m_lastStepSucceeded = true;
+    BuildStep *m_currentBuildStep = nullptr;
     QString m_currentConfiguration;
     // used to decide if we are building a project to decide when to emit buildStateChanged(Project *)
     QHash<Project *, int>  m_activeBuildSteps;
@@ -107,16 +106,6 @@ BuildManager::BuildManager(QObject *parent, QAction *cancelBuildAction)
     m_instance = this;
     d = new BuildManagerPrivate;
 
-    connect(&d->m_watcher, &QFutureWatcherBase::finished,
-            this, &BuildManager::nextBuildQueue, Qt::QueuedConnection);
-
-    connect(&d->m_watcher, &QFutureWatcherBase::progressValueChanged,
-            this, &BuildManager::progressChanged);
-    connect(&d->m_watcher, &QFutureWatcherBase::progressTextChanged,
-            this, &BuildManager::progressTextChanged);
-    connect(&d->m_watcher, &QFutureWatcherBase::progressRangeChanged,
-            this, &BuildManager::progressChanged);
-
     connect(SessionManager::instance(), &SessionManager::aboutToRemoveProject,
             this, &BuildManager::aboutToRemoveProject);
 
@@ -203,14 +192,9 @@ void BuildManager::cancel()
         if (d->m_canceling)
             return;
         d->m_canceling = true;
-        d->m_watcher.cancel();
-        if (d->m_currentBuildStep->runInGuiThread()) {
-            d->m_currentBuildStep->cancel();
-            while (d->m_canceling)
-                QApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
-        } else {
-            d->m_watcher.waitForFinished();
-        }
+        d->m_currentBuildStep->cancel();
+        while (d->m_canceling)
+            QApplication::processEvents(QEventLoop::ExcludeUserInputEvents); // TODO: Is this really necessary?
     }
 }
 
@@ -352,8 +336,6 @@ void BuildManager::addToOutputWindow(const QString &string, BuildStep::OutputFor
 
 void BuildManager::nextBuildQueue()
 {
-    d->m_futureInterfaceForAysnc = QFutureInterface<bool>();
-
     d->m_outputWindow->flush();
     if (d->m_canceling) {
         d->m_canceling = false;
@@ -375,7 +357,7 @@ void BuildManager::nextBuildQueue()
     d->m_progressFutureInterface->setProgressValueAndText(d->m_progress*100, msgProgress(d->m_progress, d->m_maxProgress));
     decrementActiveBuildSteps(d->m_currentBuildStep);
 
-    const bool success = d->m_skipDisabled || d->m_watcher.result();
+    const bool success = d->m_skipDisabled || d->m_lastStepSucceeded;
     if (success) {
         nextStep();
     } else {
@@ -397,28 +379,10 @@ void BuildManager::nextBuildQueue()
     }
 }
 
-void BuildManager::progressChanged()
+void BuildManager::progressChanged(int percent, const QString &text)
 {
-    if (!d->m_progressFutureInterface)
-        return;
-    int range = d->m_watcher.progressMaximum() - d->m_watcher.progressMinimum();
-    if (range != 0) {
-        int percent = (d->m_watcher.progressValue() - d->m_watcher.progressMinimum()) * 100 / range;
-        d->m_progressFutureInterface->setProgressValueAndText(d->m_progress * 100 + percent, msgProgress(d->m_progress, d->m_maxProgress)
-                                                              + QLatin1Char('\n') + d->m_watcher.progressText());
-    }
-}
-
-void BuildManager::progressTextChanged()
-{
-    if (!d->m_progressFutureInterface)
-        return;
-    int range = d->m_watcher.progressMaximum() - d->m_watcher.progressMinimum();
-    int percent = 0;
-    if (range != 0)
-        percent = (d->m_watcher.progressValue() - d->m_watcher.progressMinimum()) * 100 / range;
-    d->m_progressFutureInterface->setProgressValueAndText(d->m_progress*100 + percent, msgProgress(d->m_progress, d->m_maxProgress) +
-                                                          QLatin1Char('\n') + d->m_watcher.progressText());
+    if (d->m_progressFutureInterface)
+        d->m_progressFutureInterface->setProgressValueAndText(percent, text);
 }
 
 void BuildManager::nextStep()
@@ -445,12 +409,16 @@ void BuildManager::nextStep()
             return;
         }
 
-        if (d->m_currentBuildStep->runInGuiThread()) {
-            d->m_watcher.setFuture(d->m_futureInterfaceForAysnc.future());
-            d->m_currentBuildStep->run(d->m_futureInterfaceForAysnc);
-        } else {
-            d->m_watcher.setFuture(Utils::runAsync(&BuildStep::run, d->m_currentBuildStep));
-        }
+        static const auto finishedHandler = [](bool success)  {
+            d->m_lastStepSucceeded = success;
+            disconnect(d->m_currentBuildStep, nullptr, instance(), nullptr);
+            BuildManager::nextBuildQueue();
+        };
+        connect(d->m_currentBuildStep, &BuildStep::finished, instance(), finishedHandler,
+                Qt::QueuedConnection);
+        connect(d->m_currentBuildStep, &BuildStep::progress,
+                instance(), &BuildManager::progressChanged);
+        d->m_currentBuildStep->run();
     } else {
         d->m_running = false;
         d->m_previousBuildStepProject = nullptr;