Prevent multiple kiway from loading simultaneously

Each KIWAY_PLAYER has some initialization elements that may take time
before the frame is raised.  If handling is returned to the UI during
that load, we can cause reentrant issues for players.

Fixes https://gitlab.com/kicad/code/kicad/issues/4284

Fixes https://gitlab.com/kicad/code/kicad/issues/3743

kicad/kicad.h

@@ -36,6 +36,7 @@
 #include <id.h>
 #include <eda_base_frame.h>
 #include <kiway_player.h>
+#include <mutex>
 
 #define KICAD_MANAGER_FRAME_NAME   wxT( "KicadFrame" )
 
@@ -304,6 +305,9 @@ private:
     void language_change( wxCommandEvent& event );
 
     bool m_active_project;
+
+    // Mutex to allow only a single KiFace to load at one time (released when loaded)
+    std::mutex m_loading;
 };
 
 

kicad/mainframe.cpp

@@ -316,6 +316,9 @@ void KICAD_MANAGER_FRAME::RunEeschema( const wxString& aProjectSchematicFileName
 {
     KIWAY_PLAYER* frame;
 
+    // Prevent multiple KiFace loading at one time
+    const std::lock_guard<std::mutex> lock( m_loading );
+
     try
     {
         frame = Kiway().Player( FRAME_SCH, true );
@@ -361,6 +364,9 @@ void KICAD_MANAGER_FRAME::OnRunSchLibEditor( wxCommandEvent& event )
 {
     KIWAY_PLAYER* frame;
 
+    // Prevent multiple KiFace loading at one time
+    const std::lock_guard<std::mutex> lock( m_loading );
+
     try
     {
         frame = Kiway().Player( FRAME_SCH_LIB_EDITOR, true );
@@ -387,6 +393,9 @@ void KICAD_MANAGER_FRAME::RunPcbNew( const wxString& aProjectBoardFileName )
 {
     KIWAY_PLAYER* frame;
 
+    // Prevent multiple KiFace loading at one time
+    const std::lock_guard<std::mutex> lock( m_loading );
+
     try
     {
         frame = Kiway().Player( FRAME_PCB, true );
@@ -430,6 +439,9 @@ void KICAD_MANAGER_FRAME::OnRunPcbFpEditor( wxCommandEvent& event )
 {
     KIWAY_PLAYER* frame;
 
+    // Prevent multiple KiFace loading at one time
+    const std::lock_guard<std::mutex> lock( m_loading );
+
     try
     {
         frame = Kiway().Player( FRAME_PCB_MODULE_EDITOR, true );