Add write capability directly from Xdr

Author: loganharbour

include/systems/equation_systems.h

@@ -514,6 +514,15 @@ class EquationSystems : public ReferenceCountedObject<EquationSystems>,
               const unsigned int write_flags=(WRITE_DATA),
               bool partition_agnostic = true) const;
 
+  void write (std::ostream name,
+              const unsigned int write_flags=(WRITE_DATA),
+              bool partition_agnostic = true) const;
+
+  void write (Xdr & io,
+              const unsigned int write_flags=(WRITE_DATA),
+              bool partition_agnostic = true,
+              Xdr * const local_io = nullptr) const;
+
   /**
    * \returns \p true when this equation system contains
    * identical data, up to the given threshold.  Delegates

src/systems/equation_systems_io.C

@@ -381,6 +381,23 @@ void EquationSystems::write(std::string_view name,
                             const XdrMODE mode,
                             const unsigned int write_flags,
                             bool partition_agnostic) const
+{
+  Xdr io((this->processor_id()==0) ? std::string(name) : "", mode);
+
+  std::unique_ptr<Xdr> local_io;
+  // open a parallel buffer if warranted
+  if (write_flags & EquationSystems::WRITE_PARALLEL_FILES && write_flags & EquationSystems::WRITE_DATA)
+    local_io = std::make_unique<Xdr>(local_file_name(this->processor_id(),name), mode);
+
+  this->write(io, write_flags, partition_agnostic, local_io.get());
+}
+
+
+
+void EquationSystems::write(Xdr & io,
+                            const unsigned int write_flags,
+                            bool partition_agnostic,
+                            Xdr * const local_io) const
 {
   /**
    * This program implements the output of an
@@ -474,9 +491,10 @@ void EquationSystems::write(std::string_view name,
     // !this->get_mesh().is_serial())
     ;
 
-  // New scope so that io will close before we try to zip the file
+  if (write_parallel_files && write_data)
+    libmesh_assert(local_io);
+
   {
-    Xdr io((this->processor_id()==0) ? std::string(name) : "", mode);
     libmesh_assert (io.writing());
 
     LOG_SCOPE("write()", "EquationSystems");
@@ -554,21 +572,23 @@ void EquationSystems::write(std::string_view name,
     // to write vectors to disk, if wanted
     if (write_data)
       {
-        // open a parallel buffer if warranted.
-        Xdr local_io (write_parallel_files ? local_file_name(this->processor_id(),name) : "", mode);
-
         for (auto & pr : _systems)
           {
             // Ignore this system if it has been marked as hidden
             if (pr.second->hide_output()) continue;
 
             // 10.) + 11.)
             if (write_parallel_files)
-              pr.second->write_parallel_data (local_io,write_additional_data);
+              pr.second->write_parallel_data (*local_io,write_additional_data);
             else
               pr.second->write_serialized_data (io,write_additional_data);
           }
+
+        if (local_io)
+          local_io->close();
       }
+
+    io.close();
   }
 
   // the EquationSystems::write() method should look constant,