src/rtree: store free nodes as linked list

3 files changed, 72 insertions, 40 deletions

diff --git a/src/RTree.cpp b/src/RTree.cpp
index bee4641c..40343e31 100644
--- a/src/RTree.cpp
+++ b/src/RTree.cpp
@@ -11,53 +11,68 @@
 
 namespace floormat::detail {
 
-template<typename T> rtree_pool<T>::rtree_pool()
-{
-    free_list.reserve(128);
-}
+#ifdef RTREE_POOL_DEBUG
+static size_t fresh_counter, reuse_counter, dtor_counter; // NOLINT
+#endif
+
+template<typename T> rtree_pool<T>::rtree_pool() noexcept = default;
 
-template<typename T> rtree_pool<T>::~rtree_pool()
+template<typename T>
+rtree_pool<T>::~rtree_pool()
 {
-    for (auto* ptr : free_list)
-        ::operator delete(ptr);
-    free_list.clear();
-    free_list.shrink_to_fit();
+#ifdef RTREE_POOL_DEBUG
+    auto last = dtor_counter;
+#endif
+    while (free_list)
+    {
+#ifdef RTREE_POOL_DEBUG
+        ++dtor_counter;
+#endif
+        auto* p = free_list;
+        free_list = free_list->next;
+        p->data.~T();
+        delete p;
+    }
+#ifdef RTREE_POOL_DEBUG
+    if (dtor_counter != last) { Debug{} << "rtree-pool: dtor" << dtor_counter; std::fflush(stdout); }
+#endif
 }
 
 template<typename T> T* rtree_pool<T>::construct()
 {
-    if (free_list.empty())
+    if (!free_list)
     {
 #ifdef RTREE_POOL_DEBUG
-        static unsigned i = 0; Debug{} << "rtree-pool: fresh"_s << ++i; std::fflush(stdout);
+        Debug{} << "rtree-pool: fresh"_s << ++fresh_counter; std::fflush(stdout);
 #endif
-        return new T;
+        auto* ptr = new node_u;
+        auto* ret = new(&ptr->data) T;
+        return ret;
     }
     else
     {
-        auto* ret = free_list.back();
-        free_list.pop_back();
-        new (ret) T();
+        auto* ret = free_list;
+        free_list = free_list->next;
+        new (&ret->data) T();
 #ifdef RTREE_POOL_DEBUG
-        static unsigned i = 0; Debug{} << "rtree-pool: reused"_s << ++i; std::fflush(stdout);
+        Debug{} << "rtree-pool: reused"_s << ++reuse_counter; std::fflush(stdout);
 #endif
-        return ret;
+        return &ret->data;
     }
 }
 
 template<typename T> void rtree_pool<T>::free(T* ptr)
 {
     ptr->~T();
-    free_list.push_back(ptr);
+    node_p p = {.ptr = ptr };
+    node_u* n = p.data_ptr;
+    n->next = free_list;
+    free_list = n;
 }
 
 using my_rtree = RTree<uint64_t, float, 2, float>;
-
-template<> std::vector<my_rtree::Node*> rtree_pool<my_rtree::Node>::free_list = {}; // NOLINT
-template<> std::vector<my_rtree::ListNode*> rtree_pool<my_rtree::ListNode>::free_list = {}; // NOLINT
-
-template struct floormat::detail::rtree_pool<my_rtree::Node>;
-template struct floormat::detail::rtree_pool<my_rtree::ListNode>;
+template struct rtree_pool<my_rtree::Node>;
+template struct rtree_pool<my_rtree::ListNode>;
 
 } // namespace floormat::detail
 
diff --git a/src/RTree.h b/src/RTree.h
index 1a30a735..3ceb64ac 100644
--- a/src/RTree.h
+++ b/src/RTree.h
@@ -22,6 +22,28 @@
 
 namespace floormat::detail { template<typename T> struct rtree_pool; }
 
+template<typename T> struct floormat::detail::rtree_pool final
+{
+    rtree_pool() noexcept;
+    rtree_pool(const rtree_pool&) = delete;
+    rtree_pool& operator=(const rtree_pool&) = delete;
+    ~rtree_pool();
+    T* construct();
+    void free(T* pool);
+
+    union node_u {
+        union { T data; };
+        node_u* next;
+    };
+    union node_p {
+        T* ptr;
+        node_u* data_ptr;
+    };
+
+private:
+    node_u* free_list = nullptr;
+};
+
 #ifdef RTREE_STDIO
 // Fwd decl
 class RTFileStream;  // File I/O helper class, look below for implementation and notes.
@@ -45,7 +67,7 @@ class RTFileStream;  // File I/O helper class, look below for implementation and
 ///
 template<class DATATYPE, class ELEMTYPE, int NUMDIMS,
          class ELEMTYPEREAL = ELEMTYPE, int TMAXNODES = 8, int TMINNODES = TMAXNODES / 2>
-class RTree
+class RTree final
 {
 
 public:
@@ -65,7 +87,7 @@ public:
 
   RTree();
   RTree(const RTree& other);
-  virtual ~RTree() noexcept;
+  ~RTree() noexcept;
   RTree& operator=(const RTree&);
 
   /// Insert entry
@@ -212,6 +234,9 @@ public:
     Node* m_node;                                 ///< Node
   };
 
+  floormat::detail::rtree_pool<Node> node_pool;
+  floormat::detail::rtree_pool<ListNode> list_node_pool;
+
 protected:
   /// Variables for finding a split partition
   struct PartitionVars
@@ -278,6 +303,8 @@ public:
 };
 
 extern template class RTree<floormat::uint64_t, float, 2, float>;
+extern template struct floormat::detail::rtree_pool<RTree<floormat::uint64_t, float, 2, float>::Node>;
+extern template struct floormat::detail::rtree_pool<RTree<floormat::uint64_t, float, 2, float>::ListNode>;
 
 //#undef RTREE_TEMPLATE
 //#undef RTREE_QUAL
diff --git a/src/RTree.hpp b/src/RTree.hpp
index 45cbb378..046c5e1d 100644
--- a/src/RTree.hpp
+++ b/src/RTree.hpp
@@ -4,7 +4,6 @@
 
 #include <math.h>
 #include <stdlib.h>
-#include <cassert>
 #include <limits>
 #include <algorithm>
 
@@ -33,16 +32,7 @@
 #endif //Max
 
 namespace floormat::detail {
-template<typename T> struct rtree_pool final
-{
-    rtree_pool();
-    ~rtree_pool();
-    static T* construct();
-    static void free(T* pool);
 
-private:
-    static std::vector<T*> free_list; // NOLINT
-};
 
 #ifndef RTREE_NO_EXTERN_TEMPLATE_POOL
 extern template struct rtree_pool<RTree<std::uint64_t, float, 2, float>::Node>;
@@ -560,7 +550,7 @@ typename RTREE_QUAL::Node* RTREE_QUAL::AllocNode()
 #ifdef RTREE_DONT_USE_MEMPOOLS
   newNode = new Node;
 #else // RTREE_DONT_USE_MEMPOOLS
-  newNode = floormat::detail::rtree_pool<Node>::construct();
+  newNode = node_pool.construct();
 #endif // RTREE_DONT_USE_MEMPOOLS
   InitNode(newNode);
   return newNode;
@@ -575,7 +565,7 @@ void RTREE_QUAL::FreeNode(Node* a_node)
 #ifdef RTREE_DONT_USE_MEMPOOLS
   delete a_node;
 #else // RTREE_DONT_USE_MEMPOOLS
-  floormat::detail::rtree_pool<Node>::free(a_node);
+  node_pool.free(a_node);
 #endif // RTREE_DONT_USE_MEMPOOLS
 }
 
@@ -588,7 +578,7 @@ typename RTREE_QUAL::ListNode* RTREE_QUAL::AllocListNode()
 #ifdef RTREE_DONT_USE_MEMPOOLS
   return new ListNode;
 #else // RTREE_DONT_USE_MEMPOOLS
-  return floormat::detail::rtree_pool<ListNode>::construct();
+  return list_node_pool.construct();
 #endif // RTREE_DONT_USE_MEMPOOLS
 }
 
@@ -599,7 +589,7 @@ void RTREE_QUAL::FreeListNode(ListNode* a_listNode)
 #ifdef RTREE_DONT_USE_MEMPOOLS
   delete a_listNode;
 #else // RTREE_DONT_USE_MEMPOOLS
-  floormat::detail::rtree_pool<ListNode>::free(a_listNode);
+  list_node_pool.free(a_listNode);
 #endif // RTREE_DONT_USE_MEMPOOLS
 }