BUG: redistributePar -reconstruct lagrangian trashes fields (fixes #2494)

- the file removal cleanup, which makes reasonable sense for
  redistribute mode, always forced the removal of the reconstructed
  lagrangian fields (since all of the non-master fields are empty by
  definition)!

  Detect reconstruct mode (by using constructSize from the map) to
  circumvent this logic.

applications/utilities/parallelProcessing/redistributePar/parLagrangianDistributorTemplates.C

@@ -84,15 +84,32 @@ Foam::label Foam::parLagrangianDistributor::distributeFields
         )
     );
 
+
+    bool reconstruct = false;
+
     label nFields = 0;
     for (const word& objectName : fieldNames)
     {
         if (!nFields)
         {
-            Info<< "    Distributing lagrangian "
+            // Performing an all-to-one (reconstruct)?
-                << fieldType::typeName << "s\n" << endl;
+            reconstruct = returnReduce
+            (
+                (!map.constructSize() || Pstream::master()),
+                andOp<bool>()
+            );
         }
-        Info<< "        " <<  objectName << endl;
+
+        if (verbose_)
+        {
+            if (!nFields)
+            {
+                Info<< "    Distributing lagrangian "
+                    << fieldType::typeName << "s\n" << nl;
+            }
+            Info<< "        " <<  objectName << nl;
+        }
+        ++nFields;
 
         // Read if present
         IOField<Type> field
@@ -128,7 +145,7 @@ Foam::label Foam::parLagrangianDistributor::distributeFields
         {
             IOField<Type>(fieldIO, std::move(field)).write();
         }
-        else
+        else if (!reconstruct)
         {
             // When running with -overwrite it should also delete the old
             // files. Below works but is not optimal.
@@ -138,6 +155,7 @@ Foam::label Foam::parLagrangianDistributor::distributeFields
         }
     }
 
+    if (nFields && verbose_) Info<< endl;
     return nFields;
 }
 
@@ -174,9 +192,21 @@ Foam::label Foam::parLagrangianDistributor::distributeFieldFields
         )
     );
 
+    bool reconstruct = false;
+
     label nFields = 0;
     for (const word& objectName : fieldNames)
     {
+        if (!nFields)
+        {
+            // Performing an all-to-one (reconstruct)?
+            reconstruct = returnReduce
+            (
+                (!map.constructSize() || Pstream::master()),
+                andOp<bool>()
+            );
+        }
+
         if (verbose_)
         {
             if (!nFields)
@@ -227,7 +257,7 @@ Foam::label Foam::parLagrangianDistributor::distributeFieldFields
                 std::move(field)
             ).write();
         }
-        else
+        else if (!reconstruct)
         {
             // When running with -overwrite it should also delete the old
             // files. Below works but is not optimal.
@@ -309,19 +339,31 @@ Foam::label Foam::parLagrangianDistributor::distributeStoredFields
         cloud.lookupClass<Container>()
     );
 
+    bool reconstruct = false;
+
     label nFields = 0;
     forAllIters(fields, iter)
     {
         Container& field = *(iter.val());
 
+        if (!nFields)
+        {
+            // Performing an all-to-one (reconstruct)?
+            reconstruct = returnReduce
+            (
+                (!map.constructSize() || Pstream::master()),
+                andOp<bool>()
+            );
+        }
+
         if (verbose_)
         {
             if (!nFields)
             {
                 Info<< "    Distributing lagrangian "
-                    << Container::typeName << "s\n" << endl;
+                    << Container::typeName << "s\n" << nl;
             }
-            Info<< "        " <<  field.name() << endl;
+            Info<< "        " <<  field.name() << nl;
         }
         ++nFields;
 
@@ -342,7 +384,7 @@ Foam::label Foam::parLagrangianDistributor::distributeStoredFields
         {
             Container(fieldIO, std::move(field)).write();
         }
-        else
+        else if (!reconstruct)
         {
             // When running with -overwrite it should also delete the old
             // files. Below works but is not optimal.

applications/utilities/parallelProcessing/redistributePar/redistributePar.C

@@ -147,7 +147,7 @@ void createTimeDirs(const fileName& path)
             //Pout<< "Time:" << t << nl
             //    << "    raw       :" << timePath << nl
             //    << endl;
-            mkDir(timePath);
+            Foam::mkDir(timePath);
         }
     }
 
@@ -1141,18 +1141,13 @@ int main(int argc, char *argv[])
         Info<< "Reconstructing case (like reconstructParMesh)" << nl << endl;
     }
 
-
+    if ((decompose || reconstruct) && !overwrite)
-    if (decompose || reconstruct)
     {
-        if (!overwrite)
-        {
-            WarningInFunction
-                << "Working in decompose or reconstruction mode automatically"
-                << " implies -overwrite" << nl << endl;
         overwrite = true;
+        WarningInFunction
+            << "Working in -decompose or -reconstruct mode:"
+               " automatically implies -overwrite" << nl << endl;
     }
-    }
-
 
     if (!Pstream::parRun())
     {
@@ -1162,7 +1157,7 @@ int main(int argc, char *argv[])
     }
 
 
-    if (!isDir(args.rootPath()))
+    if (!Foam::isDir(args.rootPath()))
     {
         FatalErrorInFunction
             << ": cannot open root directory " << args.rootPath()
@@ -1188,7 +1183,7 @@ int main(int argc, char *argv[])
     // want to delay constructing runTime until we've synced all time
     // directories...
     const fileName procDir(fileHandler().filePath(args.path()));
-    if (isDir(procDir))
+    if (Foam::isDir(procDir))
     {
         if (decompose)
         {
@@ -2446,7 +2441,7 @@ int main(int argc, char *argv[])
                         // Remove dummy mesh created by loadOrCreateMesh
                         const bool oldParRun = Pstream::parRun(false);
                         mesh.removeFiles();
-                        rmDir(mesh.objectRegistry::objectPath());
+                        Foam::rmDir(mesh.objectRegistry::objectPath());
                         Pstream::parRun(oldParRun);  // Restore parallel state
                     }
                 }