typed-allocation-manager.hpp

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/*
  TYPED-ALLOCATION-MANAGER.hpp  -  abstract backbone to build custom memory managers 

   Copyright (C)
     2009,            Hermann Vosseler <Ichthyostega@web.de>

  **Lumiera** is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version. See the file COPYING for further details.

*/


#ifndef LIB_TYPED_ALLOCATION_MANAGER_H
#define LIB_TYPED_ALLOCATION_MANAGER_H

#include "lib/error.hpp"
#include "lib/meta/util.hpp"
#include "lib/typed-counter.hpp"
#include "include/logging.h"


#include <utility>
#include <memory>


namespace lib {
  
  using std::shared_ptr;
  
  
  
  
  class TypedAllocationManager
    {
      typedef TypedAllocationManager _TheManager;
      
    public:
      template<class XX>
      size_t numSlots()  const;
      
      
      /* ======= managing the created objects ============= */
      
      template<class XOX>
      class Killer
        {
          _TheManager* manager_;
          
        public:
          void
          operator() (XOX* victim)
            {
              REQUIRE (manager_);
              manager_->destroyElement (victim);
            }
          
        protected:
          Killer(_TheManager* m)
            : manager_(m)
            { }
        };
      
      template<class XOX>
      struct Slot
        : private Killer<XOX>
        {
          void* const storage_;
          
          shared_ptr<XOX>
          build (XOX* toTrack)
            {
              return shared_ptr<XOX> (toTrack, getDeleter());
            }
          
          Killer<XOX> const&
          getDeleter()
            {
              return *this;
            }
          
        protected:
          Slot(_TheManager* don, void* mem)
            : Killer<XOX>(don)
            , storage_(mem)
            { }
          
          friend class TypedAllocationManager;
        };
      
      
      
      
      /* ==== build objects with managed allocation ==== */
      
      template< class XX, typename...ARGS>
      shared_ptr<XX>
      create (ARGS&& ...args)
        {
          Slot<XX> slot = allocateSlot<XX>();
          try {
              return slot.build (new(slot.storage_) XX (std::forward<ARGS> (args)...) );
            }
          catch(...)
            {
              releaseSlot<XX>(slot.storage_);
              throw;
            }
        }
      
      
      
      
      
      
    protected: /* ======= Managed Allocation Implementation ========== */
      
      template<class XX>
      Slot<XX>
      allocateSlot ()
        {
          TRACE (memory, "allocate «%s»", util::typeStr<XX>().c_str());
          void* space = new char[sizeof(XX)];
          allocCnt_.inc<XX>();
          return Slot<XX> (this, space);
        }
      
      template<class XX>
      void
      releaseSlot (void* entry)
        {
          TRACE (memory, "release «%s»", util::typeStr<XX>().c_str());
          typedef char Storage[sizeof(XX)]; 
          delete[] reinterpret_cast<Storage*> (entry);
          allocCnt_.dec<XX>();
        }
      
      
      template<class XX>
      void
      destroyElement (XX* entry)
        {
          if (!entry) return;
          try
            {
              entry->~XX();
            }
          catch(...)
            {
              lumiera_err errorID = lumiera_error();
              WARN (command_dbg, "dtor of «%s» failed: %s", util::typeStr(entry).c_str()
                                                          , errorID );
            }
          releaseSlot<XX> (entry);
        }
      
      template<class>
      friend class Killer;  
      
      
    private:
      lib::TypedCounter allocCnt_;
    };
  
  
  
  template<class XX>
  size_t
  TypedAllocationManager::numSlots()  const
  {
    return allocCnt_.get<XX>();
  }

} // namespace lib
#endif