Add support for custom pointers. (#258)

* Add support for custom pointers.

* Add comment

* lowercase `OpenMP` in `CMakeLists.txt`

CMakeLists.txt

@@ -208,7 +208,7 @@ if (PHMAP_BUILD_EXAMPLES)
     # -------------------------------------------------------------
     find_package(OpenMP)
     find_package(Boost 1.70.0)
-    if (OPENMP_FOUND AND Boost_FOUND AND "cxx_std_20" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
+    if (OpenMP_FOUND AND Boost_FOUND AND "cxx_std_20" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
        add_executable(ex_llil4map examples/llil4map.cc phmap.natvis)
        target_include_directories(ex_llil4map PRIVATE ${Boost_INCLUDE_DIRS})
        target_compile_features(ex_llil4map PUBLIC cxx_std_20)
@@ -219,11 +219,17 @@ if (PHMAP_BUILD_EXAMPLES)
        target_link_libraries(ex_llil4map PRIVATE OpenMP::OpenMP_CXX)
        target_compile_options(ex_llil4map PRIVATE "${OpenMP_CXX_FLAGS}")
 
+       file(COPY examples/llil_utils DESTINATION "${CMAKE_CURRENT_BINARY_DIR}")
+    endif()
+
+    if (Boost_FOUND)
+       add_executable(ex_custom_pointer examples/custom_pointer.cc phmap.natvis)
+       target_include_directories(ex_custom_pointer PRIVATE ${Boost_INCLUDE_DIRS})
+
        add_executable(ex_llil examples/llil.cc phmap.natvis)
        target_include_directories(ex_llil PRIVATE ${Boost_INCLUDE_DIRS})
        target_compile_features(ex_llil PUBLIC cxx_std_20)
-       
-       file(COPY examples/llil_utils DESTINATION "${CMAKE_CURRENT_BINARY_DIR}")
+       target_link_libraries(ex_llil Threads::Threads)
     endif()
 
     target_link_libraries(ex_knucleotide Threads::Threads)

examples/custom_pointer.cc

@@ -0,0 +1,64 @@
+#include <boost/interprocess/managed_mapped_file.hpp>
+#include <scoped_allocator>
+#include <parallel_hashmap/phmap.h>
+#include <vector>
+#include <cstdint>
+#include <iostream>
+
+using mmap_file_t = boost::interprocess::managed_mapped_file;
+
+template <typename T>
+using bi_alloc_t = boost::interprocess::allocator<T, boost::interprocess::managed_mapped_file::segment_manager>;
+
+template <typename T>
+using scoped_alloc_t = std::scoped_allocator_adaptor<T>;
+
+void simple_map() {
+   struct LatpLon {
+      int32_t latp;
+      int32_t lon;
+   };
+
+   using nodestore_pair_t = std::pair<const uint64_t, LatpLon>;
+   using map_t            = phmap::flat_hash_map<const uint64_t, LatpLon, std::hash<uint64_t>, std::equal_to<uint64_t>,
+                                                 bi_alloc_t<nodestore_pair_t>>;
+
+   auto mmap_file =
+      boost::interprocess::managed_mapped_file(boost::interprocess::open_or_create, "map_iv.dat", 1000000);
+   map_t* map = mmap_file.find_or_construct<map_t>("node_store")(mmap_file.get_segment_manager());
+
+   for (unsigned int i = 0; i < 1000; ++i) {
+      LatpLon p = {10, 10};
+      map->emplace(i, p);
+   }
+
+   std::cout << map->at(10).latp << " " << map->at(10).lon << std::endl;
+}
+
+void scoped_map() {
+   using way_t           = std::vector<uint64_t, bi_alloc_t<uint64_t>>;
+   using waystore_pair_t = std::pair<const uint64_t, way_t>;
+   using map_t           = phmap::flat_hash_map<const uint64_t, way_t, std::hash<uint64_t>, std::equal_to<uint64_t>,
+                                                std::scoped_allocator_adaptor<bi_alloc_t<waystore_pair_t>>>;
+
+   auto mmap_file =
+      boost::interprocess::managed_mapped_file(boost::interprocess::open_or_create, "map_iv.dat", 1000000);
+   map_t* map = mmap_file.find_or_construct<map_t>("ways_store")(mmap_file.get_segment_manager());
+
+   for (unsigned int i = 0; i < 1000; ++i) {
+      std::vector<uint64_t> init = {1, 2, 3, 4};
+      map->emplace(std::piecewise_construct, std::forward_as_tuple(i), std::forward_as_tuple(init.begin(), init.end()));
+   }
+
+   std::cout << map->at(10).size() << std::endl;
+   for (auto const& i : map->at(10))
+      std::cout << i << " ";
+   std::cout << std::endl;
+}
+
+int main()
+{
+    simple_map();
+    scoped_map();
+    return 0;
+}

examples/llil.cc

@@ -63,7 +63,6 @@
 
 #include <utility>
 #include <iterator>
-#include <execution>
 #include <algorithm>
 #include <filesystem>
 

parallel_hashmap/phmap.h

@@ -926,12 +926,7 @@ private:
     using IsDecomposable = IsDecomposable<void, PolicyTraits, Hash, Eq, Ts...>;
 
 public:
-    static_assert(std::is_same<pointer, value_type*>::value,
-                  "Allocators with custom pointer types are not supported");
-    static_assert(std::is_same<const_pointer, const value_type*>::value,
-                  "Allocators with custom pointer types are not supported");
-
-    class iterator 
+    class iterator
     {
         friend class raw_hash_set;
 

parallel_hashmap/phmap_base.h

@@ -4189,7 +4189,7 @@ void* Allocate(Alloc* alloc, size_t n) {
   using A = typename phmap::allocator_traits<Alloc>::template rebind_alloc<M>;
   using AT = typename phmap::allocator_traits<Alloc>::template rebind_traits<M>;
   A mem_alloc(*alloc);
-  void* p = AT::allocate(mem_alloc, (n + sizeof(M) - 1) / sizeof(M));
+  void* p = &*AT::allocate(mem_alloc, (n + sizeof(M) - 1) / sizeof(M)); // `&*` to support custom pointers such as boost offset_ptr.
   assert(reinterpret_cast<uintptr_t>(p) % Alignment == 0 &&
          "allocator does not respect alignment");
   return p;