From 16497b0362244407a139479b6e15834cf709779c Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Sat, 2 Oct 2021 00:00:43 +0200
Subject: tracker/pt: fix rare crash due to QProcess use across threads

This was caused by QProcess in video/ps3eye getting created from the UI
thread, then recreated on the Point Tracker's thread.
---
 tracker-pt/ftnoir_tracker_pt.cpp | 37 +++++++++++++++++++------------------
 tracker-pt/ftnoir_tracker_pt.h   |  2 +-
 2 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/tracker-pt/ftnoir_tracker_pt.cpp b/tracker-pt/ftnoir_tracker_pt.cpp
index 93074883..b996448b 100644
--- a/tracker-pt/ftnoir_tracker_pt.cpp
+++ b/tracker-pt/ftnoir_tracker_pt.cpp
@@ -28,16 +28,12 @@ Tracker_PT::Tracker_PT(pointer<pt_runtime_traits> const& traits) :
     traits { traits },
     s { traits->get_module_name() },
     point_extractor { traits->make_point_extractor() },
-    camera { traits->make_camera() },
     frame { traits->make_frame() }
 {
     opencv_init();
 
-    connect(s.b.get(), &bundle_::saving, this, &Tracker_PT::maybe_reopen_camera, Qt::DirectConnection);
-    connect(s.b.get(), &bundle_::reloading, this, &Tracker_PT::maybe_reopen_camera, Qt::DirectConnection);
-
+    connect(s.b.get(), &bundle_::saving, this, [this]{ reopen_camera_flag = true; }, Qt::DirectConnection);
     connect(&s.fov, value_::value_changed<int>(), this, &Tracker_PT::set_fov, Qt::DirectConnection);
-    set_fov(s.fov);
 }
 
 Tracker_PT::~Tracker_PT()
@@ -53,11 +49,21 @@ void Tracker_PT::run()
 {
     portable::set_curthread_name("tracker/pt");
 
-    if (!maybe_reopen_camera())
-        return;
-
     while(!isInterruptionRequested())
     {
+        if (reopen_camera_flag)
+        {
+            reopen_camera_flag = false;
+            if (camera)
+                camera->stop();
+            camera = traits->make_camera();
+            set_fov(s.fov);
+            {
+                QMutexLocker l(&camera_mtx);
+                (void)camera->start(s);
+            }
+        }
+
         pt_camera_info info;
         bool new_frame = false;
 
@@ -111,17 +117,11 @@ void Tracker_PT::run()
     }
 }
 
-bool Tracker_PT::maybe_reopen_camera()
-{
-    QMutexLocker l(&camera_mtx);
-
-    return camera->start(s);
-}
-
 void Tracker_PT::set_fov(int value)
 {
     QMutexLocker l(&camera_mtx);
-    camera->set_fov(value);
+    if (camera)
+        camera->set_fov(value);
 }
 
 module_status Tracker_PT::start_tracker(QFrame* video_frame)
@@ -206,9 +206,10 @@ int Tracker_PT::get_n_points()
 bool Tracker_PT::get_cam_info(pt_camera_info& info)
 {
     QMutexLocker l(&camera_mtx);
-    bool ret;
+    bool ret = false;
 
-    std::tie(ret, info) = camera->get_info();
+    if (camera)
+        std::tie(ret, info) = camera->get_info();
     return ret;
 }
 
diff --git a/tracker-pt/ftnoir_tracker_pt.h b/tracker-pt/ftnoir_tracker_pt.h
index fa3d94ad..50e51405 100644
--- a/tracker-pt/ftnoir_tracker_pt.h
+++ b/tracker-pt/ftnoir_tracker_pt.h
@@ -50,7 +50,6 @@ struct Tracker_PT : QThread, ITracker
 private:
     void run() override;
 
-    bool maybe_reopen_camera();
     void set_fov(int value);
 
     pointer<pt_runtime_traits> traits;
@@ -74,6 +73,7 @@ private:
 
     std::atomic<unsigned> point_count { 0 };
     std::atomic<bool> ever_success = false;
+    std::atomic<bool> reopen_camera_flag = true;
     mutable QMutex center_lock, data_lock;
     point_filter filter{s};
 };
-- 
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