From 22be6355d500a6da80211f7be8baa1d0951f819a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Franz=20P=C3=B6schel?= <franz.poeschel@gmail.com>
Date: Thu, 21 Jul 2022 10:20:29 +0200
Subject: [PATCH] Use simpler file existence check in Windows workaround

---
 include/openPMD/IO/ADIOS/ADIOS2IOHandler.hpp |  3 ++
 src/IO/ADIOS/ADIOS2IOHandler.cpp             | 43 +++++++-------------
 2 files changed, 18 insertions(+), 28 deletions(-)

diff --git a/include/openPMD/IO/ADIOS/ADIOS2IOHandler.hpp b/include/openPMD/IO/ADIOS/ADIOS2IOHandler.hpp
index a5652db778..707fa8c77d 100644
--- a/include/openPMD/IO/ADIOS/ADIOS2IOHandler.hpp
+++ b/include/openPMD/IO/ADIOS/ADIOS2IOHandler.hpp
@@ -153,6 +153,9 @@ class ADIOS2IOHandlerImpl
 
     void checkFile(Writable *, Parameter<Operation::CHECK_FILE> &) override;
 
+    // MPI Collective
+    bool checkFile(std::string fullFilePath) const;
+
     void
     createPath(Writable *, Parameter<Operation::CREATE_PATH> const &) override;
 
diff --git a/src/IO/ADIOS/ADIOS2IOHandler.cpp b/src/IO/ADIOS/ADIOS2IOHandler.cpp
index ef7845d435..edb6fb8279 100644
--- a/src/IO/ADIOS/ADIOS2IOHandler.cpp
+++ b/src/IO/ADIOS/ADIOS2IOHandler.cpp
@@ -508,14 +508,20 @@ void ADIOS2IOHandlerImpl::checkFile(
     std::string name =
         fullPath(parameters.name + fileSuffix(/* verbose = */ false));
 
+    using FileExists = Parameter<Operation::CHECK_FILE>::FileExists;
+    *parameters.fileExists = checkFile(name) ? FileExists::Yes : FileExists::No;
+}
+
+bool ADIOS2IOHandlerImpl::checkFile(std::string fullFilePath) const
+{
     if (m_engineType == "bp3")
     {
-        if (!auxiliary::ends_with(name, ".bp"))
+        if (!auxiliary::ends_with(fullFilePath, ".bp"))
         {
             /*
              * BP3 will add this ending if not specified
              */
-            name += ".bp";
+            fullFilePath += ".bp";
         }
     }
     else if (m_engineType == "sst")
@@ -523,17 +529,15 @@ void ADIOS2IOHandlerImpl::checkFile(
         /*
          * SST will add this ending indiscriminately
          */
-        name += ".sst";
+        fullFilePath += ".sst";
     }
-
     char fileExists = false;
-    auxiliary::runOnRankZero(m_communicator, [&fileExists, &name]() {
-        fileExists =
-            auxiliary::file_exists(name) || auxiliary::directory_exists(name);
+    auxiliary::runOnRankZero(m_communicator, [&fileExists, &fullFilePath]() {
+        fileExists = auxiliary::file_exists(fullFilePath) ||
+            auxiliary::directory_exists(fullFilePath);
     });
     auxiliary::MPI_Bcast_fromRankZero(m_communicator, &fileExists);
-    using FileExists = Parameter<Operation::CHECK_FILE>::FileExists;
-    *parameters.fileExists = fileExists ? FileExists::Yes : FileExists::No;
+    return fileExists;
 }
 
 void ADIOS2IOHandlerImpl::createPath(
@@ -2669,25 +2673,8 @@ namespace detail
                  * files. So, we first check for file existence and switch to
                  * create mode if it does not exist.
                  */
-                {
-                    try
-                    {
-                        adios2::Engine checkExists =
-                            m_IO.Open(m_file, adios2::Mode::Read);
-                        if (!checkExists)
-                        {
-                            tempMode = adios2::Mode::Write;
-                        }
-                        else
-                        {
-                            checkExists.Close();
-                        }
-                    }
-                    catch (...)
-                    {
-                        tempMode = adios2::Mode::Write;
-                    }
-                }
+                tempMode = m_impl->checkFile(m_file) ? adios2::Mode::Append
+                                                     : adios2::Mode::Write;
                 [[fallthrough]];
 #endif
             case adios2::Mode::Write: {