using mutex to safely delete pendula

src/Simulation.cpp

@@ -15,10 +15,14 @@ Simulation::Simulation() {
 };
 
 void Simulation::draw(QPainter *p, int screenSize) {
+	pendulaMutex.lock();
+
 	double scale = screenSize * 0.95 / size;
 
 	for (const auto pendulum : pendula)
 		pendulum->draw(p, scale);
+
+	pendulaMutex.unlock();
 }
 
 void Simulation::update() {
@@ -40,12 +44,14 @@ void Simulation::update() {
 }
 
 void Simulation::clearPendula() {
-	auto deleteLater = pendula;
+	pendulaMutex.lock();
+
+	for (auto p : pendula)
+		delete p;
 	pendula.clear();
 	pendula.shrink_to_fit();
-	QThread::usleep(500000);
-	for (auto p : deleteLater)
-		delete p;
+
+	pendulaMutex.unlock();
 }
 
 void Simulation::addPendula(const std::vector<Pendulum *> &add) {

src/Simulation.h

@@ -2,6 +2,7 @@
 #include <cstdint>
 #include <QObject>
 #include <chrono>
+#include <mutex>
 
 using namespace std::chrono;
 
@@ -28,6 +29,7 @@ public slots:
 private slots:
 	void update();
 private:
+	std::mutex pendulaMutex;
 	QTimer * timer;
 	int updateInterval = 17;
 	std::vector<Pendulum *> pendula;