Merge topic 'timestamp-static-notice'

f90a80d9 vtkTimeStamp: add a notice for future linker-ghost chasing souls
5481d80b vtkTimeStamp: remove old comment
64dbb110 typo: fix name of "Schwarz" counter references
Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Utkarsh Ayachit <utkarsh.ayachit@kitware.com>
Acked-by: Robert Maynard <robert.maynard@kitware.com>
Merge-request: !6036

Common/Core/vtkObjectFactory.h

@@ -281,7 +281,7 @@ private:
   void operator=(const vtkObjectFactory&) = delete;
 };
 
-// Implementation detail for Schwartz counter idiom.
+// Implementation detail for Schwarz counter idiom.
 class VTKCOMMONCORE_EXPORT vtkObjectFactoryRegistryCleanup
 {
 public:

Common/Core/vtkTimeStamp.cxx

@@ -17,9 +17,6 @@
 #include "vtkObjectFactory.h"
 #include "vtkWindows.h"
 
-// We use the Schwarz Counter idiom to make sure that GlobalTimeStamp
-// is initialized before any other class uses it.
-
 #include "vtkAtomicTypes.h"
 
 //-------------------------------------------------------------------------
@@ -32,6 +29,27 @@ vtkTimeStamp* vtkTimeStamp::New()
 //-------------------------------------------------------------------------
 void vtkTimeStamp::Modified()
 {
+  // Here because of a static destruction error? You're not the first. After
+  // discussion of the tradeoffs, the cost of adding a Schwarz counter on this
+  // static to ensure it gets destructed is unlikely to be worth the cost over
+  // just leaking it.
+  //
+  // Solutions and their tradeoffs:
+  //
+  //  - Schwarz counter: each VTK class now has a static initializer function
+  //    that increments and integer. This cannot be inlined or optimized away.
+  //    Adds latency to ParaView startup.
+  //  - Separate library for this static. This adds another library to VTK
+  //    which are already legion. It could not be folded into a kit because
+  //    that would bring you back to the same problem you have today.
+  //  - Leak a heap allocation for it. It's 24 bytes, leaked exactly once, and
+  //    is easily suppressed in Valgrind.
+  //
+  // The last solution has been decided to have the smallest downside of these.
+  //
+  //  static const vtkAtomicUIntXX* GlobalTimeStamp = new vtkAtomicUIntXX(0);
+  //
+  // Good luck!
 #if defined(VTK_USE_64BIT_TIMESTAMPS) || VTK_SIZEOF_VOID_P == 8
   static vtkAtomicUInt64 GlobalTimeStamp(0);
 #else

Parallel/DIY/vtkDIYUtilities.h

@@ -131,7 +131,7 @@ struct Serialization<vtkDataSet*>
 };
 }
 
-// Implementation detail for Schwartz counter idiom.
+// Implementation detail for Schwarz counter idiom.
 class VTKPARALLELDIY_EXPORT vtkDIYUtilitiesCleanup
 {
 public: