From 90c7e77075c33e4d5da2a483830412c3f7d0a108 Mon Sep 17 00:00:00 2001
From: Kenneth Moreland <morelandkd@ornl.gov>
Date: Fri, 7 Oct 2022 14:51:21 -0600
Subject: [PATCH] Initialize DIY in vtkm::cont::Initialize

This has the side effect of initialing MPI_Init (and will also
call MPI_Finalize at program exit). However, if the calling
code has already called MPI_Init, then nothing will happen.
Thus, if the calling code wants to manage MPI_Init/Finalize,
it can do so as long as it does before it initializes VTK-m.
---
 docs/changelog/mpi-init.md |  8 ++++++++
 vtkm/cont/Initialize.cxx   | 22 +++++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100644 docs/changelog/mpi-init.md

diff --git a/docs/changelog/mpi-init.md b/docs/changelog/mpi-init.md
new file mode 100644
index 000000000..fe6041807
--- /dev/null
+++ b/docs/changelog/mpi-init.md
@@ -0,0 +1,8 @@
+# Initialize DIY in vtkm::cont::Initialize
+
+This has the side effect of initialing MPI_Init (and will also
+call MPI_Finalize at program exit). However, if the calling 
+code has already called MPI_Init, then nothing will happen. 
+Thus, if the calling code wants to manage MPI_Init/Finalize,
+it can do so as long as it does before it initializes VTK-m.
+
diff --git a/vtkm/cont/Initialize.cxx b/vtkm/cont/Initialize.cxx
index 2c909a1ea..56483691c 100644
--- a/vtkm/cont/Initialize.cxx
+++ b/vtkm/cont/Initialize.cxx
@@ -15,6 +15,8 @@
 #include <vtkm/cont/internal/OptionParser.h>
 #include <vtkm/cont/internal/OptionParserArguments.h>
 
+#include <vtkm/thirdparty/diy/environment.h>
+
 #include <memory>
 #include <sstream>
 
@@ -114,7 +116,7 @@ InitializeResult Initialize(int& argc, char* argv[], InitializeOptions opts)
   const std::string loggingHelp = "  " + loggingFlag +
     " <#|INFO|WARNING|ERROR|FATAL|OFF> \tSpecify a log level (when logging is enabled).";
 
-  // initialize logging first -- it'll pop off the options it consumes:
+  // initialize logging and diy first -- they'll pop off the options they consume:
   if (argc == 0 || argv == nullptr)
   {
     vtkm::cont::InitLogging();
@@ -123,6 +125,19 @@ InitializeResult Initialize(int& argc, char* argv[], InitializeOptions opts)
   {
     vtkm::cont::InitLogging(argc, argv, loggingFlag);
   }
+  if (!vtkmdiy::mpi::environment::initialized())
+  {
+    if (argc == 0 || argv == nullptr)
+    {
+      // If initialized, will be deleted on program exit (calling MPI_Finalize if necessary)
+      static vtkmdiy::mpi::environment diyEnvironment;
+    }
+    else
+    {
+      // If initialized, will be deleted on program exit (calling MPI_Finalize if necessary)
+      static vtkmdiy::mpi::environment diyEnvironment(argc, argv);
+    }
+  }
 
   { // Parse VTKm options
     std::vector<opt::Descriptor> usage;
@@ -359,8 +374,9 @@ InitializeResult Initialize(int& argc, char* argv[], InitializeOptions opts)
 VTKM_CONT
 InitializeResult Initialize()
 {
-  vtkm::cont::InitLogging();
-  return InitializeResult{};
+  int argc = 0;
+  char** argv = nullptr;
+  return Initialize(argc, argv);
 }
 }
 } // end namespace vtkm::cont