do less global memory fences in atomics

6 files changed, 21 insertions, 22 deletions

diff --git a/options/scoped.cpp b/options/scoped.cpp
index ef5b94d6..f5e219e2 100644
--- a/options/scoped.cpp
+++ b/options/scoped.cpp
@@ -10,7 +10,7 @@
 namespace options {
 
 // XXX hack: the flag shouldn't be here as action at distance -sh 20160926
-static std::atomic<bool> teardown_flag{false};
+static std::atomic<bool> teardown_flag = false;
 [[nodiscard]] static bool set_teardown_flag(bool value);
 static void ensure_thread();
 static bool is_tracker_teardown();
diff --git a/pose-widget/pose-widget.cpp b/pose-widget/pose-widget.cpp
index 943fc0ad..e9bf1d01 100644
--- a/pose-widget/pose-widget.cpp
+++ b/pose-widget/pose-widget.cpp
@@ -62,7 +62,7 @@ void pose_transform::run()
         {
             lock_guard l(mtx);
 
-            if (fresh)
+            if (fresh.load(std::memory_order_relaxed))
                 goto end;
 
             rotation = rotation_;
@@ -88,8 +88,7 @@ void pose_widget::rotate_async(double xAngle, double yAngle, double zAngle, doub
     if (!check_is_visible())
         return;
 
-    bool expected = true;
-    if (xform.fresh.compare_exchange_weak(expected, false))
+    if (bool X = true; xform.fresh.compare_exchange_weak(X, false, std::memory_order_relaxed))
     {
         repaint();
         xform.rotate_async(xAngle, yAngle, zAngle, x, y, z);
@@ -266,7 +265,7 @@ void pose_transform::project_quad_texture()
     {
         lock_guard l(mtx2);
         image.swap(image2);
-        fresh = true;
+        fresh.store(true, std::memory_order_relaxed);
         return;
     }
 
@@ -358,7 +357,7 @@ void pose_transform::project_quad_texture()
     {
         lock_guard l2(mtx2);
         image.swap(image2);
-        fresh = true;
+        fresh.store(true, std::memory_order_relaxed);
     }
 }
 
diff --git a/pose-widget/pose-widget.hpp b/pose-widget/pose-widget.hpp
index aa51957e..1e50b392 100644
--- a/pose-widget/pose-widget.hpp
+++ b/pose-widget/pose-widget.hpp
@@ -84,7 +84,7 @@ struct pose_transform final : QThread
     };
 
     std::vector<uv_> uv_vec;
-    std::atomic<bool> fresh{false};
+    std::atomic<bool> fresh = false;
 
     static constexpr int w = 320, h = 240;
 };
diff --git a/proto-simconnect/ftnoir_protocol_sc.cpp b/proto-simconnect/ftnoir_protocol_sc.cpp
index 9a1db9b5..42cdf596 100644
--- a/proto-simconnect/ftnoir_protocol_sc.cpp
+++ b/proto-simconnect/ftnoir_protocol_sc.cpp
@@ -62,7 +62,7 @@ void simconnect::run()
                         break;
                     }
 
-                    if (reconnect)
+                    if (reconnect.load(std::memory_order_relaxed))
                         break;
 
                     if (!SUCCEEDED(hr = simconnect_calldispatch(handle, event_handler, (void*)this)))
diff --git a/tracker-pt/ftnoir_tracker_pt.cpp b/tracker-pt/ftnoir_tracker_pt.cpp
index 4223da26..a1a0dc1c 100644
--- a/tracker-pt/ftnoir_tracker_pt.cpp
+++ b/tracker-pt/ftnoir_tracker_pt.cpp
@@ -70,7 +70,7 @@ void Tracker_PT::run()
             *preview_frame = *frame;
 
             point_extractor->extract_points(*frame, *preview_frame, points);
-            point_count = points.size();
+            point_count.store(points.size(), std::memory_order_relaxed);
 
             const f fx = pt_camera_info::get_focal_length(info.fov, info.res_x, info.res_y);
             const bool success = points.size() >= PointModel::N_POINTS;
@@ -86,7 +86,7 @@ void Tracker_PT::run()
                                         PointModel(s),
                                         info,
                                         s.dynamic_pose ? s.init_phase_timeout : 0);
-                    ever_success = true;
+                    ever_success.store(true, std::memory_order_relaxed);
                 }
 
                 QMutexLocker l2(&data_lock);
@@ -146,7 +146,7 @@ module_status Tracker_PT::start_tracker(QFrame* video_frame)
 
 void Tracker_PT::data(double *data)
 {
-    if (ever_success)
+    if (ever_success.load(std::memory_order_relaxed))
     {
         Affine X_CM;
         {
@@ -196,7 +196,7 @@ bool Tracker_PT::center()
 
 int Tracker_PT::get_n_points()
 {
-    return int(point_count);
+    return (int)point_count.load(std::memory_order_relaxed);
 }
 
 bool Tracker_PT::get_cam_info(pt_camera_info& info)
diff --git a/video/video-widget.cpp b/video/video-widget.cpp
index e73d34db..fb380fc4 100644
--- a/video/video-widget.cpp
+++ b/video/video-widget.cpp
@@ -25,11 +25,10 @@ video_widget::video_widget(QWidget* parent) : QWidget(parent)
 
 void video_widget::update_image(const QImage& img)
 {
-    QMutexLocker l(&mtx);
-
-    if (freshp)
+    if (freshp.load(std::memory_order_relaxed))
         return;
-    freshp = true;
+
+    QMutexLocker l(&mtx);
 
     unsigned nbytes = (unsigned)(img.bytesPerLine() * img.height());
     vec.resize(nbytes); vec.shrink_to_fit();
@@ -37,6 +36,8 @@ void video_widget::update_image(const QImage& img)
 
     texture = QImage((const unsigned char*) vec.data(), img.width(), img.height(), img.bytesPerLine(), img.format());
     texture.setDevicePixelRatio(devicePixelRatioF());
+
+    freshp.store(true, std::memory_order_relaxed);
 }
 
 void video_widget::paintEvent(QPaintEvent*)
@@ -49,16 +50,15 @@ void video_widget::paintEvent(QPaintEvent*)
 
 void video_widget::update_and_repaint()
 {
+    if (!freshp.load(std::memory_order_relaxed))
+        return;
+
     if (!check_is_visible())
         return;
 
     QMutexLocker l(&mtx);
-
-    if (freshp)
-    {
-        freshp = false;
-        repaint();
-    }
+    repaint();
+    freshp.store(false, std::memory_order_relaxed);
 }
 
 void video_widget::resizeEvent(QResizeEvent*)