[PATCH] kernel-shark: Implement proper reser for the OpenGL widget

[Yordan Karadzhov <ykaradzhov@vmware.com>]

When loading a new trace.dat file the OpenGL widget has to be properly
reset. One important operation of this reset is to set the "_data"
pointer to NULL. This will block all attempts for drawing something
before the widget is set again. The bug was introduced in

7d057ae56 ("kernel-shark-qt: Add Trace Graph widget")

but had no effect until

94efea960 ("kernel-shark-qt: Handle the case when the range of ...")

because the number of bins of the model was zero, so nothing was plotted
anyway.

Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fixes: 7d057ae56 ("kernel-shark-qt: Add Trace Graph widget")
Signed-off-by: Yordan Karadzhov <ykaradzhov@vmware.com>
---
 kernel-shark/src/KsGLWidget.cpp   | 9 +++++++++
 kernel-shark/src/KsGLWidget.hpp   | 2 ++
 kernel-shark/src/KsTraceGraph.cpp | 6 ++----
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/kernel-shark/src/KsGLWidget.cpp b/kernel-shark/src/KsGLWidget.cpp
index 917e86d..7a050c2 100644
--- a/kernel-shark/src/KsGLWidget.cpp
+++ b/kernel-shark/src/KsGLWidget.cpp
@@ -109,6 +109,15 @@ void KsGLWidget::paintGL()
 	_mState->activeMarker().draw();
 }
 
+/** Reset (empty) the widget. */
+void KsGLWidget::reset()
+{
+	_cpuList = {};
+	_taskList = {};
+	_data = nullptr;
+	_model.reset();
+}
+
 /** Reimplemented event handler used to receive mouse press events. */
 void KsGLWidget::mousePressEvent(QMouseEvent *event)
 {
diff --git a/kernel-shark/src/KsGLWidget.hpp b/kernel-shark/src/KsGLWidget.hpp
index 6fbf534..95f307b 100644
--- a/kernel-shark/src/KsGLWidget.hpp
+++ b/kernel-shark/src/KsGLWidget.hpp
@@ -37,6 +37,8 @@ public:
 
 	void paintGL() override;
 
+	void reset();
+
 	void mousePressEvent(QMouseEvent *event);
 
 	void mouseMoveEvent(QMouseEvent *event);
diff --git a/kernel-shark/src/KsTraceGraph.cpp b/kernel-shark/src/KsTraceGraph.cpp
index 844c794..6087e96 100644
--- a/kernel-shark/src/KsTraceGraph.cpp
+++ b/kernel-shark/src/KsTraceGraph.cpp
@@ -201,15 +201,13 @@ void KsTraceGraph::setMarkerSM(KsDualMarkerSM *m)
 /** Reset (empty) the widget. */
 void KsTraceGraph::reset()
 {
-	/* Clear the all graph lists and update. */
-	_glWindow._cpuList = {};
-	_glWindow._taskList = {};
+	/* Reset (empty) the OpenGL widget. */
+	_glWindow.reset();
 
 	_labelP2.setText("");
 	for (auto l1: {&_labelI1, &_labelI2, &_labelI3, &_labelI4, &_labelI5})
 		l1->setText("");
 
-	_glWindow.model()->reset();
 	_selfUpdate();
 	for (auto l2: {&_labelXMin, &_labelXMid, &_labelXMax})
 		l2->setText("");
-- 
2.17.1