ENH: reduce allocations/overhead when reading PtrList

- replace SLList with direct handling (like a hand-rolled DynamicList)

ENH: support PtrList transfer for polyMesh::addZones

src/OpenFOAM/containers/PtrLists/PtrList/PtrListIO.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2018-2021 OpenCFD Ltd.
+    Copyright (C) 2018-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -27,7 +27,6 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "PtrList.H"
-#include "SLList.H"
 #include "Istream.H"
 #include "INew.H"
 
@@ -97,11 +96,10 @@ void Foam::PtrList<T>::readIstream(Istream& is, const INew& inew)
     }
     else if (tok.isPunctuation(token::BEGIN_LIST))
     {
-        // "(...)" : read as SLList and transfer contents
-        // This would be more efficient (fewer allocations, lower overhead)
-        // using a DynamicList, but then we have circular dependencies
+        // "(...)" : read like a DynamicList
 
-        SLList<T*> slList;
+        // The length read
+        label len = 0;
 
         is >> tok;
         while (!tok.isPunctuation(token::END_LIST))
@@ -115,18 +113,25 @@ void Foam::PtrList<T>::readIstream(Istream& is, const INew& inew)
                     << exit(FatalIOError);
             }
 
-            slList.append(inew(is).ptr());
+            if (!len)
+            {
+                // Initial reserved size (avoid unnecessary doubling)
+                resize(64);
+            }
+            else if (len == this->size())
+            {
+                resize(2*len);
+            }
+
+            T* p = inew(is).ptr();
+            set(len, p);
+            ++len;
+
             is >> tok;
         }
 
-        resize(slList.size());
-
-        // A list of pointers - can simply shallow copy them
-        label i = 0;
-        for (T* ptr : slList)
-        {
-            set(i++, ptr);
-        }
+        // Set list length to that read
+        resize(len);
     }
     else
     {

src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2018-2021 OpenCFD Ltd.
+    Copyright (C) 2018-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -90,13 +90,7 @@ void Foam::Detail::PtrListDetail<T>::free()
 
     for (label i=0; i<len; ++i)
     {
-        T* ptr = ptrs[i];
-
-        if (ptr)
-        {
-            delete ptr;
-        }
-
+        delete ptrs[i];
         ptrs[i] = nullptr;
     }
 }

src/OpenFOAM/db/IOstreams/IOstreams/INew.H

@@ -31,8 +31,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef INew_H
-#define INew_H
+#ifndef Foam_INew_H
+#define Foam_INew_H
 
 #include "autoPtr.H"
 
@@ -41,7 +41,8 @@ Description
 namespace Foam
 {
 
-// Forward declarations
+// Forward Declarations
+class dictionary;
 class Istream;
 
 /*---------------------------------------------------------------------------*\
@@ -53,9 +54,8 @@ class INew
 {
 public:
 
-    //- Construct null
-    INew()
-    {}
+    //- Default construct
+    INew() = default;
 
     //- New from Istream
     autoPtr<T> operator()(Istream& is) const

src/OpenFOAM/meshes/polyMesh/polyMesh.C

@@ -1011,57 +1011,39 @@ void Foam::polyMesh::addPatches
 
 void Foam::polyMesh::addZones
 (
-    const List<pointZone*>& pz,
-    const List<faceZone*>& fz,
-    const List<cellZone*>& cz
+    PtrList<pointZone>&& pz,
+    PtrList<faceZone>&& fz,
+    PtrList<cellZone>&& cz
 )
 {
-    if (pointZones().size() || faceZones().size() || cellZones().size())
+    if (pointZones_.size() || faceZones_.size() || cellZones_.size())
     {
         FatalErrorInFunction
             << "point, face or cell zone already exists"
             << abort(FatalError);
     }
 
-    // Point zones
+    // Point zones - take ownership of the pointers
     if (pz.size())
     {
-        pointZones_.setSize(pz.size());
-
-        // Copy the zone pointers
-        forAll(pz, pI)
-        {
-            pointZones_.set(pI, pz[pI]);
-        }
-
+        pointZones_.clear();
+        pointZones_.transfer(pz);
         pointZones_.writeOpt(IOobject::AUTO_WRITE);
     }
 
-    // Face zones
+    // Face zones - take ownership of the pointers
     if (fz.size())
     {
-        faceZones_.setSize(fz.size());
-
-        // Copy the zone pointers
-        forAll(fz, fI)
-        {
-            faceZones_.set(fI, fz[fI]);
-        }
-
+        faceZones_.clear();
+        faceZones_.transfer(fz);
         faceZones_.writeOpt(IOobject::AUTO_WRITE);
     }
 
-    // Cell zones
+    // Cell zones - take ownership of the pointers
     if (cz.size())
     {
-        cellZones_.setSize(cz.size());
-
-        // Copy the zone pointers
-        forAll(cz, cI)
-        {
-            cellZones_.set(cI, cz[cI]);
-        }
-
+        cellZones_.clear();
+        cellZones_.transfer(cz);
         cellZones_.writeOpt(IOobject::AUTO_WRITE);
     }
 }
@@ -1080,6 +1062,23 @@ void Foam::polyMesh::addPatches
 }
 
 
+void Foam::polyMesh::addZones
+(
+    const List<pointZone*>& pz,
+    const List<faceZone*>& fz,
+    const List<cellZone*>& cz
+)
+{
+    // Acquire ownership of the pointers
+    addZones
+    (
+        PtrList<pointZone>(const_cast<List<pointZone*>&>(pz)),
+        PtrList<faceZone>(const_cast<List<faceZone*>&>(fz)),
+        PtrList<cellZone>(const_cast<List<cellZone*>&>(cz))
+    );
+}
+
+
 const Foam::pointField& Foam::polyMesh::points() const
 {
     if (clearedPrimitives_)

src/OpenFOAM/meshes/polyMesh/polyMesh.H

@@ -606,6 +606,14 @@ public:
                 const bool validBoundary = true
             );
 
+            //- Add mesh zones
+            void addZones
+            (
+                PtrList<pointZone>&& pz,
+                PtrList<faceZone>&& fz,
+                PtrList<cellZone>&& cz
+            );
+
             //- Add mesh zones
             void addZones
             (

src/OpenFOAM/meshes/polyMesh/zones/ZoneMesh/ZoneMesh.H

@@ -271,7 +271,8 @@ public:
         //- Clear the zones
         void clear();
 
-        bool hasFaceAreas() const { return bool(zoneMapPtr_); }
+        //- The zoneMap has been allocated
+        bool hasZoneMap() const noexcept { return bool(zoneMapPtr_); }
 
 
     // Member Operators