Make Application::quit() thread-safe

Signed-off-by: falkTX <falktx@falktx.com>

dgl/src/ApplicationPrivateData.cpp

@@ -32,6 +32,7 @@ Application::PrivateData::PrivateData(const bool standalone)
                          standalone ? PUGL_WORLD_THREADS : 0x0)),
       isStandalone(standalone),
       isQuitting(false),
+      isQuittingInNextCycle(false),
       isStarting(true),
       visibleWindows(0),
       windows(),
@@ -92,6 +93,12 @@ void Application::PrivateData::oneWindowClosed() noexcept
 
 void Application::PrivateData::idle(const uint timeoutInMs)
 {
+    if (isQuittingInNextCycle)
+    {
+        quit();
+        isQuittingInNextCycle = false;
+    }
+
     if (world != nullptr)
     {
         const double timeoutInSeconds = timeoutInMs != 0
@@ -112,6 +119,12 @@ void Application::PrivateData::quit()
 {
     DISTRHO_SAFE_ASSERT_RETURN(isStandalone,);
 
+    if (! isQuittingInNextCycle)
+    {
+        isQuittingInNextCycle = true;
+        return;
+    }
+
     isQuitting = true;
 
 #ifndef DPF_TEST_APPLICATION_CPP

dgl/src/ApplicationPrivateData.hpp

@@ -39,6 +39,9 @@ struct Application::PrivateData {
     /** Whether the applicating is about to quit, or already stopped. Defaults to false. */
     bool isQuitting;
 
+    /** Helper for safely close everything from main thread. */
+    bool isQuittingInNextCycle;
+
     /** Whether the applicating is starting up, that is, no windows have been made visible yet. Defaults to true. */
     bool isStarting;