From fbeccb3954e6f45851b2ae6dd888932b3ffff8bc Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Wed, 11 May 2022 00:15:46 +0200
Subject: [PATCH] Use wxAtomicInt for the global initialization counter

This is slightly more efficient and simpler than using a separate
critical section and can easily be done now that wxAtomicInc() returns
the new value.

No real changes.
---
 src/common/init.cpp | 34 +++++++++-------------------------
 1 file changed, 9 insertions(+), 25 deletions(-)

diff --git a/src/common/init.cpp b/src/common/init.cpp
index 6b5956956a..e6d33d088d 100644
--- a/src/common/init.cpp
+++ b/src/common/init.cpp
@@ -28,7 +28,7 @@
 #endif
 
 #include "wx/init.h"
-#include "wx/thread.h"
+#include "wx/atomic.h"
 
 #include "wx/scopedptr.h"
 #include "wx/except.h"
@@ -130,22 +130,20 @@ static inline void Use(void *) { }
 static struct InitData
 {
     InitData()
+        : nInitCount(0)
     {
-        nInitCount = 0;
-
 #if wxUSE_UNICODE
         argc = argcOrig = 0;
         // argv = argvOrig = NULL; -- not even really needed
 #endif // wxUSE_UNICODE
     }
 
-    // critical section protecting the counter and allowing to call
-    // wxInitialize() concurrently from different threads
-    wxCRIT_SECT_DECLARE_MEMBER(csInit);
-
     // number of times wxInitialize() was called minus the number of times
     // wxUninitialize() was
-    size_t nInitCount;
+    //
+    // it is atomic to allow more than one thread to call wxInitialize() but
+    // only one of them to actually initialize the library
+    wxAtomicInt nInitCount;
 
 #if wxUSE_UNICODE
     int argc;
@@ -531,17 +529,11 @@ bool wxInitialize()
 
 bool wxInitialize(int& argc, wxChar **argv)
 {
-    {
-    wxCRIT_SECT_LOCKER(lockInit, gs_initData.csInit);
-
-    if ( gs_initData.nInitCount++ )
+    if ( wxAtomicInc(gs_initData.nInitCount) != 1 )
     {
         // already initialized
         return true;
     }
-    } // Do not keep the critical section locked, this could potentially result
-      // in deadlocks and is unnecessary anyhow as wxEntryStart() will be
-      // called exactly once and so doesn't need to be protected.
 
     return wxEntryStart(argc, argv);
 }
@@ -549,15 +541,11 @@ bool wxInitialize(int& argc, wxChar **argv)
 #if wxUSE_UNICODE
 bool wxInitialize(int& argc, char **argv)
 {
-    {
-    wxCRIT_SECT_LOCKER(lockInit, gs_initData.csInit);
-
-    if ( gs_initData.nInitCount++ )
+    if ( wxAtomicInc(gs_initData.nInitCount) != 1 )
     {
         // already initialized
         return true;
     }
-    } // See the comment in the overload above.
 
     return wxEntryStart(argc, argv);
 }
@@ -565,12 +553,8 @@ bool wxInitialize(int& argc, char **argv)
 
 void wxUninitialize()
 {
-    {
-    wxCRIT_SECT_LOCKER(lockInit, gs_initData.csInit);
-
-    if ( --gs_initData.nInitCount != 0 )
+    if ( wxAtomicDec(gs_initData.nInitCount) != 0 )
         return;
-    } // Don't keep the critical section locked during cleanup call neither.
 
     wxEntryCleanup();
 }