vtkIOSSReader: Clear Cache when needed

Cache is now fully cleared only when a new restart
file is about to be read. The unused cache entries
are still cleared at the end of every ReadMesh

IO/IOSS/vtkIOSSReader.cxx

@@ -364,10 +364,15 @@ int vtkIOSSReader::ReadMesh(
   // dbaseHandles are handles for individual files this instance will to read to
   // satisfy the request. Can be >= 0.
   const auto dbaseHandles = internals.GetDatabaseHandles(piece, npieces, timestep);
-  // if we have restart files, we need to release the regions that are no longer needed.
+  // if we have restart files, and the previously read regions are no longer needed.
   if (internals.HaveRestartFiles() && !internals.HaveCreatedRegions(dbaseHandles))
   {
+    // then we need to release them and, if requested, clear their cached information
     internals.ReleaseRegions();
+    if (!this->GetCaching())
+    {
+      internals.ClearCache();
+    }
   }
 
   // Read global data. Since this should be same on all ranks, we only read on
@@ -509,9 +514,7 @@ int vtkIOSSReader::ReadMesh(
       collection->GetDataAssembly()->InitializeFromXML(xml.c_str());
     }
   }
-
-  if (!this->GetCaching() ||
-    internals.GetFormat() == vtkIOSSUtilities::DatabaseFormatType::CATALYST)
+  if (internals.GetFormat() == vtkIOSSUtilities::DatabaseFormatType::CATALYST)
   {
     // We don't want to hold on to the cache for longer than the RequestData pass.
     // For we clear it entirely here.
@@ -519,6 +522,7 @@ int vtkIOSSReader::ReadMesh(
   }
   else
   {
+    // removed unused cache entries.
     internals.ClearCacheUnused();
   }
   return 1;

IO/IOSS/vtkIOSSReaderInternal.h

@@ -132,20 +132,7 @@ public:
    */
   void ClearCache() { this->Cache.Clear(); }
   void ResetCacheAccessCounts() { this->Cache.ResetAccessCounts(); }
-  void ClearCacheUnused()
-  {
-    switch (this->Format)
-    {
-      case vtkIOSSUtilities::DatabaseFormatType::CATALYST:
-        // For Catalyst, we don't want to hold on to the cache for longer than
-        // the RequestData pass. For we clear it entirely here.
-        this->Cache.Clear();
-        break;
-      default:
-        this->Cache.ClearUnused();
-        break;
-    }
-  }
+  void ClearCacheUnused() { this->Cache.ClearUnused(); }
   ///@}
 
   /**