From 02a6cee99fdb0cd8c19d2f89d0b04c7f4af1f45c Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Tue, 20 Nov 2018 08:00:19 +0100
Subject: [PATCH] glScope: use atomic variable for the data changed indicator

---
 sdrgui/gui/glscope.cpp | 30 ++++++++++++++++--------------
 sdrgui/gui/glscope.h   |  2 +-
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/sdrgui/gui/glscope.cpp b/sdrgui/gui/glscope.cpp
index bdba1e1eb..6cb63c444 100644
--- a/sdrgui/gui/glscope.cpp
+++ b/sdrgui/gui/glscope.cpp
@@ -33,7 +33,7 @@ GLScope::GLScope(QWidget* parent) :
     m_processingTraceIndex(-1),
     m_bufferIndex(0),
     m_displayMode(DisplayX),
-    m_dataChanged(false),
+    m_dataChanged(0),
     m_configChanged(false),
     m_sampleRate(0),
     m_timeOfsProMill(0),
@@ -103,11 +103,13 @@ void GLScope::newTraces(std::vector<float *>* traces)
 {
     if (traces->size() > 0)
     {
-        if(!m_mutex.tryLock(2))
+        if (!m_mutex.tryLock(2)) {
             return;
+        }
 
-        m_traces = traces;
-        m_dataChanged = true;
+        if (m_dataChanged.testAndSetOrdered(0, 1)) {
+            m_traces = traces;
+        }
 
         m_mutex.unlock();
     }
@@ -117,12 +119,15 @@ void GLScope::newTraces(std::vector<float *>* traces, int traceIndex)
 {
     if (traces->size() > 0)
     {
-        if(!m_mutex.tryLock(2))
+        if(!m_mutex.tryLock(2)) {
             return;
+        }
 
-        m_processingTraceIndex.store(traceIndex);
-        m_traces = &traces[traceIndex];
-        m_dataChanged = true;
+        if (m_dataChanged.testAndSetOrdered(0, 1))
+        {
+            m_processingTraceIndex.store(traceIndex);
+            m_traces = &traces[traceIndex];
+        }
 
         m_mutex.unlock();
     }
@@ -192,9 +197,7 @@ void GLScope::resizeGL(int width, int height)
 
 void GLScope::paintGL()
 {
-    if (!m_mutex.tryLock(2))
-    {
-        m_processingTraceIndex.store(-1);
+    if (!m_mutex.tryLock(2)) {
         return;
     }
 
@@ -205,8 +208,6 @@ void GLScope::paintGL()
 //    qDebug("GLScope::paintGL: m_traceCounter: %d", m_traceCounter);
 //    m_traceCounter = 0;
 
-    m_dataChanged = false;
-
     QOpenGLFunctions *glFunctions = QOpenGLContext::currentContext()->functions();
     glFunctions->glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
     glFunctions->glClear(GL_COLOR_BUFFER_BIT);
@@ -940,6 +941,7 @@ void GLScope::paintGL()
         } // trace length > 0
     } // XY mixed + polar display
 
+    m_dataChanged.store(0);
     m_processingTraceIndex.store(-1);
     m_mutex.unlock();
 }
@@ -1995,7 +1997,7 @@ void GLScope::drawChannelOverlay(
 
 void GLScope::tick()
 {
-    if(m_dataChanged) {
+    if (m_dataChanged.load()) {
         update();
     }
 }
diff --git a/sdrgui/gui/glscope.h b/sdrgui/gui/glscope.h
index 6120a2217..c93ed46d7 100644
--- a/sdrgui/gui/glscope.h
+++ b/sdrgui/gui/glscope.h
@@ -95,7 +95,7 @@ private:
     DisplayMode m_displayMode;
     QTimer m_timer;
     QMutex m_mutex;
-    bool m_dataChanged;
+    QAtomicInt m_dataChanged;
     bool m_configChanged;
     int m_sampleRate;
     int m_timeOfsProMill;