From 9c64c9af5dfb23a2ff4e4e229494f1815a7b043d Mon Sep 17 00:00:00 2001
From: jean-pierre charras <jp.charras@wanadoo.fr>
Date: Tue, 24 Mar 2020 20:47:49 +0100
Subject: [PATCH] Kicad manager: fix an issue on Windows when killing Kicad.
 For some obscure reason, on Windows, when killing Kicad from the Windows task
 manager if a editor frame (schematic, library, board editor or fp editor) is
 open and has some edition to save, OnCloseWindow is run twice *at the same
 time*, creating race conditions between OnCloseWindow() code.

Fixes #4072
https://gitlab.com/kicad/code/kicad/issues/4072
---
 kicad/mainframe.cpp | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/kicad/mainframe.cpp b/kicad/mainframe.cpp
index d6c69d0e36..c75661485d 100644
--- a/kicad/mainframe.cpp
+++ b/kicad/mainframe.cpp
@@ -209,6 +209,22 @@ void KICAD_MANAGER_FRAME::OnSize( wxSizeEvent& event )
 
 void KICAD_MANAGER_FRAME::OnCloseWindow( wxCloseEvent& Event )
 {
+#ifdef _WINDOWS_
+    // For some obscure reason, on Windows, when killing Kicad from the Windows task manager
+    // if a editor frame (schematic, library, board editor or fp editor) is open and has
+    // some edition to save, OnCloseWindow is run twice *at the same time*, creating race
+    // conditions between OnCloseWindow() code.
+    // Therefore I added (JPC) a ugly hack to discard the second call (unwanted) during
+    // execution of the first call (only one call is right).
+    // Note also if there is no change made in editors, this behavior does not happen.
+    static std::atomic<unsigned int> lock_close_event( 0 );
+
+    if( ++lock_close_event > 1 )    // Skip extra calls
+    {
+        return;
+    }
+#endif
+
     if( Kiway().PlayersClose( false ) )
     {
         int px, py;
@@ -233,6 +249,10 @@ void KICAD_MANAGER_FRAME::OnCloseWindow( wxCloseEvent& Event )
 
         Destroy();
     }
+
+#ifdef _WINDOWS_
+    lock_close_event = 0;   // Reenable event management
+#endif
 }