mmap tarfiles directly when mmapping is enabled, instead of copying data into separate mmapped block

Co-authored-by: Kajari Ghosh <ghoshkaj@gmail.com>

include/engine/datafacade/mmap_memory_allocator.hpp

@@ -10,6 +10,7 @@
 #include <boost/iostreams/device/mapped_file.hpp>
 
 #include <memory>
+#include <string>
 
 namespace osrm
 {
@@ -24,8 +25,7 @@ namespace datafacade
 class MMapMemoryAllocator : public ContiguousBlockAllocator
 {
   public:
-    explicit MMapMemoryAllocator(const storage::StorageConfig &config,
-                                 const boost::filesystem::path &memory_file);
+    explicit MMapMemoryAllocator(const storage::StorageConfig &config);
     ~MMapMemoryAllocator() override final;
 
     // interface to give access to the datafacades
@@ -33,8 +33,8 @@ class MMapMemoryAllocator : public ContiguousBlockAllocator
 
   private:
     storage::SharedDataIndex index;
-    util::vector_view<char> mapped_memory;
-    boost::iostreams::mapped_file mapped_memory_file;
+    std::vector<boost::iostreams::mapped_file> mapped_memory_files;
+    std::string rtree_filename;
 };
 
 } // namespace datafacade