intersegment_ptr.hpp

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   //!Increments internal
   //!offset
   void inc_offset(std::ptrdiff_t bytes)
   {
      this->set_from_pointer(static_cast<char*>(this->get_pointer()) + bytes);
   }

   //!Decrements internal
   //!offset
   void dec_offset(std::ptrdiff_t bytes)
   {
      this->set_from_pointer(static_cast<char*>(this->get_pointer()) - bytes);
   }

   //////////////////////////////////////
   //////////////////////////////////////
   //////////////////////////////////////

   flat_map_intersegment()
      :  intersegment_base()
   {}

   ~flat_map_intersegment()
   {}

   private:

   class segment_group_t
   {
      struct segment_data
      {
         void *addr;
         std::size_t size;
      };
      vector<segment_data> m_segments;
      multi_segment_services &m_ms_services;
      
      public:
      segment_group_t(multi_segment_services &ms_services)
         :  m_ms_services(ms_services)
      {}

      void push_back(void *addr, std::size_t size)
      {
         segment_data d = { addr, size };
         m_segments.push_back(d);
      }

      void pop_back()
      {
         assert(!m_segments.empty());
         m_segments.erase(--m_segments.end());
      }


      void *address_of(std::size_t segment_id)
      {
         assert(segment_id < (std::size_t)m_segments.size());
         return m_segments[segment_id].addr;
      }

      void clear_segments()
      {  m_segments.clear();  }

      std::size_t get_size() const
      {  return m_segments.size();  }

      multi_segment_services &get_multi_segment_services() const
      {  return m_ms_services;   }

      friend bool operator< (const segment_group_t&l, const segment_group_t &r)
      {  return &l.m_ms_services < &r.m_ms_services;   }
   };

   struct segment_info_t
   {
      std::size_t size;
      std::size_t id;
      segment_group_t *group;
      segment_info_t()
         :  size(0), id(0), group(0)
      {}
   };

   typedef set<segment_group_t>  segment_groups_t;

   typedef boost::interprocess::flat_map
      <const void * 
      ,segment_info_t
      ,std::less<const void *> >          ptr_to_segment_info_t;

   struct mappings_t : Mutex
   {
      //!Mutex to preserve integrity in multi-threaded
      //!enviroments
      typedef Mutex        mutex_type;
      //!Maps base addresses and segment information 
      //!(size and segment group and id)*
      
      ptr_to_segment_info_t      m_ptr_to_segment_info;

      ~mappings_t()
      {
         //Check that all mappings have been erased
         assert(m_ptr_to_segment_info.empty());
      }
   };

   //Static members
   static mappings_t       s_map;
   static segment_groups_t s_groups;
   public:

   typedef segment_group_t*      segment_group_id;

   //!Returns the segment and offset
   //!of an address
   static void get_segment_info_and_offset(const void *ptr, segment_info_t &segment, std::size_t &offset, void *&base)
   {
      //------------------------------------------------------------------
      boost::interprocess::scoped_lock<typename mappings_t::mutex_type> lock(s_map);
      //------------------------------------------------------------------
      base = 0;
      if(s_map.m_ptr_to_segment_info.empty()){
         segment = segment_info_t();
         offset  = reinterpret_cast<const char*>(ptr) - static_cast<const char*>(0);
         return;
      }
      //Find the first base address greater than ptr
      typename ptr_to_segment_info_t::iterator it 
         = s_map.m_ptr_to_segment_info.upper_bound(ptr);
      if(it == s_map.m_ptr_to_segment_info.begin()){
         segment = segment_info_t();
         offset  = reinterpret_cast<const char*>(ptr) - static_cast<const char *>(0);
      }
      //Go to the previous one
      --it;
      char *      segment_base = const_cast<char*>(reinterpret_cast<const char*>(it->first));
      std::size_t segment_size = it->second.size;
      
      if(segment_base <= reinterpret_cast<const char*>(ptr) &&
         (segment_base + segment_size) >= reinterpret_cast<const char*>(ptr)){
         segment = it->second;
         offset  = reinterpret_cast<const char*>(ptr) - segment_base;
         base = segment_base;
      }
      else{
         segment = segment_info_t();
         offset  = reinterpret_cast<const char*>(ptr) - static_cast<const char*>(0);
      }
   }

   //!Associates a segment defined by group/id with a base address and size.
   //!Returns false if the group is not found or there is an error
   static void insert_mapping(segment_group_id group_id, void *ptr, std::size_t size)
   {
      //------------------------------------------------------------------
      boost::interprocess::scoped_lock<typename mappings_t::mutex_type> lock(s_map);
      //------------------------------------------------------------------

      typedef typename ptr_to_segment_info_t::value_type value_type;
      typedef typename ptr_to_segment_info_t::iterator   iterator;
      typedef std::pair<iterator, bool>                  it_b_t;

      segment_info_t info;
      info.group = group_id;
      info.size  = size;
      info.id    = group_id->get_size();

      it_b_t ret = s_map.m_ptr_to_segment_info.insert(value_type(ptr, info));
      assert(ret.second);

      value_eraser<ptr_to_segment_info_t> v_eraser(s_map.m_ptr_to_segment_info, ret.first);
      group_id->push_back(ptr, size);
      v_eraser.release();
   }

   static bool erase_last_mapping(segment_group_id group_id)
   {
      //------------------------------------------------------------------
      boost::interprocess::scoped_lock<typename mappings_t::mutex_type> lock(s_map);
      //------------------------------------------------------------------
      if(!group_id->get_size()){
         return false;
      }
      else{
         void *addr = group_id->address_of(group_id->get_size()-1);
         group_id->pop_back();
         std::size_t erased = s_map.m_ptr_to_segment_info.erase(addr);
         (void)erased;
         assert(erased);
         return true;
      }
   }

   static segment_group_id new_segment_group(multi_segment_services *services)
   {
      {  //------------------------------------------------------------------
         boost::interprocess::scoped_lock<typename mappings_t::mutex_type> lock(s_map);
         //------------------------------------------------------------------
         typedef typename segment_groups_t::iterator iterator;
         std::pair<iterator, bool> ret =
            s_groups.insert(segment_group_t(*services));
         assert(ret.second);
         return &*ret.first;
      }      
   }

   static bool delete_group(segment_group_id id)
   {
      {  //------------------------------------------------------------------
         boost::interprocess::scoped_lock<typename mappings_t::mutex_type> lock(s_map);
         //------------------------------------------------------------------
         bool success = 1u == s_groups.erase(segment_group_t(*id));
         if(success){
            typedef typename ptr_to_segment_info_t::iterator ptr_to_segment_info_it;
            ptr_to_segment_info_it it(s_map.m_ptr_to_segment_info.begin());
            while(it != s_map.m_ptr_to_segment_info.end()){
               if(it->second.group == id){
                  it = s_map.m_ptr_to_segment_info.erase(it);
               }
               else{
                  ++it;
               }
            }
         }
         return success;
      }      
   }
};

//!Static map-segment_info associated with
//!flat_map_intersegment<>
template <class Mutex>
typename flat_map_intersegment<Mutex>::mappings_t 
   flat_map_intersegment<Mutex>::s_map;

//!Static segment group container associated with
//!flat_map_intersegment<>
template <class Mutex>
typename flat_map_intersegment<Mutex>::segment_groups_t 
   flat_map_intersegment<Mutex>::s_groups;

//!A smart pointer that can point to a pointee that resides in another memory 
//!memory mapped or shared memory segment.
template <class T>
class intersegment_ptr : public flat_map_intersegment<interprocess_mutex>
{
   typedef flat_map_intersegment<interprocess_mutex> PT;
   typedef intersegment_ptr<T>                  self_t;
   typedef PT                                      base_t;

   void unspecified_bool_type_func() const {}
   typedef void (self_t::*unspecified_bool_type)() const;

   public:
   typedef T *                                     pointer;
   typedef typename detail::add_reference<T>::type reference;
   typedef T                                       value_type;
   typedef std::ptrdiff_t                          difference_type;
   typedef std::random_access_iterator_tag         iterator_category;

   public:   //Public Functions

   //!Constructor from raw pointer (allows "0" pointer conversion).
   //!Never throws.
   intersegment_ptr(pointer ptr = 0)
   {  base_t::set_from_pointer(ptr);   }

   //!Constructor from other pointer.
   //!Never throws.
   template <class U>
   intersegment_ptr(U *ptr){  base_t::set_from_pointer(pointer(ptr)); }

   //!Constructor from other intersegment_ptr
   //!Never throws
   intersegment_ptr(const intersegment_ptr& ptr) 
   {  base_t::set_from_other(ptr);   }

   //!Constructor from other intersegment_ptr. If pointers of pointee types are 
   //!convertible, intersegment_ptrs will be convertibles. Never throws.
   template<class T2>
   intersegment_ptr(const intersegment_ptr<T2> &ptr) 
   {  pointer p(ptr.get());   (void)p; base_t::set_from_other(ptr); }

   //!Emulates static_cast operator.
   //!Never throws.
   template<class U>
   intersegment_ptr(const intersegment_ptr<U> &r, detail::static_cast_tag)
   {  base_t::set_from_pointer(static_cast<T*>(r.get())); }

   //!Emulates const_cast operator.
   //!Never throws.
   template<class U>
   intersegment_ptr(const intersegment_ptr<U> &r, detail::const_cast_tag)
   {  base_t::set_from_pointer(const_cast<T*>(r.get())); }

   //!Emulates dynamic_cast operator.
   //!Never throws.
   template<class U>
   intersegment_ptr(const intersegment_ptr<U> &r, detail::dynamic_cast_tag)
   {  base_t::set_from_pointer(dynamic_cast<T*>(r.get())); }

   //!Emulates reinterpret_cast operator.
   //!Never throws.
   template<class U>
   intersegment_ptr(const intersegment_ptr<U> &r, detail::reinterpret_cast_tag)
   {  base_t::set_from_pointer(reinterpret_cast<T*>(r.get())); }

   //!Obtains raw pointer from offset.
   //!Never throws.
   pointer get()const
   {  return static_cast<pointer>(base_t::get_pointer());   }

   //!Pointer-like -> operator. It can return 0 pointer.
   //!Never throws.
   pointer operator->() const           
   {  return self_t::get(); }

   //!Dereferencing operator, if it is a null intersegment_ptr behavior 
   //!is undefined. Never throws.
   reference operator* () const           
   {  return *(self_t::get());   }

   //!Indexing operator.
   //!Never throws.
   reference operator[](std::ptrdiff_t idx) const   
   {  return self_t::get()[idx];  }

   //!Assignment from pointer (saves extra conversion).
   //!Never throws.
   intersegment_ptr& operator= (pointer from)
   {  base_t::set_from_pointer(from); return *this;  }

   //!Assignment from other intersegment_ptr.
   //!Never throws.
   intersegment_ptr& operator= (const intersegment_ptr &ptr)
   {  base_t::set_from_other(ptr);  return *this;  }

   //!Assignment from related intersegment_ptr. If pointers of pointee types 
   //!are assignable, intersegment_ptrs will be assignable. Never throws.
   template <class T2>
   intersegment_ptr& operator= (const intersegment_ptr<T2> & ptr)
   {  
      pointer p(ptr.get());   (void)p; 
      base_t::set_from_other(ptr); return *this;   
   }