Merge topic 'fix-amrex-particle-reader-without-top-level-header'

2f2329d0 AMReX - continue reading particle file when top level header does not exist

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Reviewed-by: Corey Wetterer-Nelson (Kitware) <c.wetterer-nelson@kitware.com>
Merge-request: !11809

Documentation/release/dev/fix-amrex-particle-reader-without-top-level-header.md

+# Fix AMReX particle reader for files without top-level header
+
+The `vtkAMReXParticlesReader` now continues to read the particles even when a
+top level header does not exist. Normally, the reader obtained the data time step
+from the top level header. It initializes the time step to 0 if that header file
+does not exist.

IO/AMR/vtkAMReXParticlesReader.cxx

@@ -35,8 +35,8 @@ VTK_ABI_NAMESPACE_BEGIN
 namespace
 {
 // returns empty string on failure.
-std::string ReadAndBroadCastFile(
-  const std::string& filename, vtkMultiProcessController* controller, vtkAMReXParticlesReader* self)
+std::string ReadAndBroadCastFile(const std::string& filename, vtkMultiProcessController* controller,
+  vtkAMReXParticlesReader* self, bool errorOnFailedToOpenFile = true)
 {
   std::string contents;
   if (controller == nullptr || controller->GetLocalProcessId() == 0)
@@ -62,7 +62,7 @@ std::string ReadAndBroadCastFile(
       delete[] data;
       data = nullptr;
     }
-    else
+    else if (errorOnFailedToOpenFile)
     {
       vtkErrorWithObjectMacro(self, "Failed to open file '" << filename << "'.");
     }
@@ -791,21 +791,25 @@ bool vtkAMReXParticlesReader::ReadMetaData()
 
   // read the top level header to get time information
   const std::string gridHdrFileName = this->PlotFileName + "/Header";
-  const auto gridHeaderData = ::ReadAndBroadCastFile(gridHdrFileName, this->Controller, this);
-  if (gridHeaderData.empty())
+  const auto gridHeaderData = ::ReadAndBroadCastFile(
+    gridHdrFileName, this->Controller, this, /*errorOnFailedToOpenFile=*/false);
+  if (!gridHeaderData.empty())
   {
-    return false;
+    auto gridHeaderPtr = new vtkAMReXGridHeader();
+    if (!gridHeaderPtr->Parse(gridHeaderData))
+    {
+      delete gridHeaderPtr;
+      return false;
+    }
+    // Add time information.
+    this->dataTimeStep = gridHeaderPtr->time;
+    delete gridHeaderPtr;
   }
-
-  auto gridHeaderPtr = new vtkAMReXGridHeader();
-  if (!gridHeaderPtr->Parse(gridHeaderData))
+  else
   {
-    delete gridHeaderPtr;
-    return false;
+    // there is no top level header.
+    this->dataTimeStep = 0;
   }
-  // Add time information.
-  this->dataTimeStep = gridHeaderPtr->time;
-  delete gridHeaderPtr;
 
   this->Header = headerPtr;
   this->Header->PopulatePointArraySelection(this->PointDataArraySelection);