allocator_common.hpp

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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2008. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/interprocess for documentation.
//
//////////////////////////////////////////////////////////////////////////////

#ifndef BOOST_INTERPROCESS_DETAIL_NODE_ALLOCATOR_COMMON_HPP
#define BOOST_INTERPROCESS_DETAIL_NODE_ALLOCATOR_COMMON_HPP

#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>
#include <boost/interprocess/segment_manager.hpp>
#include <boost/interprocess/interprocess_fwd.hpp>
#include <boost/interprocess/detail/utilities.hpp> //pointer_to_other, get_pointer
#include <utility>   //std::pair
#include <boost/utility/addressof.hpp> //boost::addressof
#include <boost/assert.hpp>   //BOOST_ASSERT
#include <boost/interprocess/exceptions.hpp> //bad_alloc
#include <boost/interprocess/sync/scoped_lock.hpp> //scoped_lock
#include <boost/interprocess/allocators/allocation_type.hpp> //allocation_type
#include <algorithm> //std::swap


namespace boost {
namespace interprocess {
namespace detail {

//!Object function that creates the node allocator if it is not created and
//!increments reference count if it is already created
template<class NodePool>
struct get_or_create_node_pool_func
{
   
   //!This connects or constructs the unique instance of node_pool_t
   //!Can throw boost::interprocess::bad_alloc
   void operator()()
   {
      //Find or create the node_pool_t
      mp_node_pool =    mp_segment_manager->template find_or_construct
                        <NodePool>(unique_instance)(mp_segment_manager);
      //If valid, increment link count
      if(mp_node_pool != 0)
         mp_node_pool->inc_ref_count();
   }

   //!Constructor. Initializes function
   //!object parameters
   get_or_create_node_pool_func(typename NodePool::segment_manager *mngr)
      : mp_segment_manager(mngr){}
   
   NodePool                            *mp_node_pool;
   typename NodePool::segment_manager  *mp_segment_manager;
};

template<class NodePool>
inline NodePool *get_or_create_node_pool(typename NodePool::segment_manager *mgnr)
{
   detail::get_or_create_node_pool_func<NodePool> func(mgnr);
   mgnr->atomic_func(func);
   return func.mp_node_pool;
}

//!Object function that decrements the reference count. If the count 
//!reaches to zero destroys the node allocator from memory. 
//!Never throws
template<class NodePool>
struct destroy_if_last_link_func
{
   //!Decrements reference count and destroys the object if there is no 
   //!more attached allocators. Never throws
   void operator()()
   {
      //If not the last link return
      if(mp_node_pool->dec_ref_count() != 0) return;

      //Last link, let's destroy the segment_manager
      mp_node_pool->get_segment_manager()->template destroy<NodePool>(unique_instance); 
   }  

   //!Constructor. Initializes function
   //!object parameters
   destroy_if_last_link_func(NodePool *pool) 
      : mp_node_pool(pool)
   {}

   NodePool                           *mp_node_pool;
};

//!Destruction function, initializes and executes destruction function 
//!object. Never throws
template<class NodePool>
inline void destroy_node_pool_if_last_link(NodePool *pool)
{
   //Get segment manager
   typename NodePool::segment_manager *mngr = pool->get_segment_manager();
   //Execute destruction functor atomically
   destroy_if_last_link_func<NodePool>func(pool);
   mngr->atomic_func(func);
}

template<class NodePool>
class cache_impl
{
   typedef typename NodePool::segment_manager::
      void_pointer                                    void_pointer;
   typedef typename pointer_to_other
      <void_pointer, NodePool>::type                  node_pool_ptr;
   typedef typename NodePool::multiallocation_chain   multiallocation_chain;
   node_pool_ptr           mp_node_pool;
   multiallocation_chain   m_cached_nodes;
   std::size_t             m_max_cached_nodes;

   public:
   typedef typename NodePool::multiallocation_iterator   multiallocation_iterator;
   typedef typename NodePool::segment_manager            segment_manager;

   cache_impl(segment_manager *segment_mngr, std::size_t max_cached_nodes)
      : mp_node_pool(get_or_create_node_pool<NodePool>(segment_mngr))
      , m_max_cached_nodes(max_cached_nodes)
   {}

   cache_impl(const cache_impl &other)
      : mp_node_pool(other.get_node_pool())
      , m_max_cached_nodes(other.get_max_cached_nodes())
   {
      mp_node_pool->inc_ref_count();
   }

   ~cache_impl()
   {
      this->deallocate_all_cached_nodes();
      detail::destroy_node_pool_if_last_link(detail::get_pointer(mp_node_pool));   
   }

   NodePool *get_node_pool() const
   {  return detail::get_pointer(mp_node_pool); }

   segment_manager *get_segment_manager() const
   {  return mp_node_pool->get_segment_manager(); }

   std::size_t get_max_cached_nodes() const
   {  return m_max_cached_nodes; }

   void *cached_allocation()
   {
      //If don't have any cached node, we have to get a new list of free nodes from the pool
      if(m_cached_nodes.empty()){
         mp_node_pool->allocate_nodes(m_cached_nodes, m_max_cached_nodes/2);
      }
      return m_cached_nodes.pop_front();
   }

   multiallocation_iterator cached_allocation(std::size_t n)
   {
      multiallocation_chain chain;
      std::size_t count = n;
      BOOST_TRY{
         //If don't have any cached node, we have to get a new list of free nodes from the pool
         while(!m_cached_nodes.empty() && count--){
            void *ret = m_cached_nodes.pop_front();
            chain.push_back(ret);
         }

         if(chain.size() != n){
            mp_node_pool->allocate_nodes(chain, n - chain.size());
         }
         assert(chain.size() == n);
         chain.splice_back(m_cached_nodes);
         return multiallocation_iterator(chain.get_it());
      }
      BOOST_CATCH(...){
         this->cached_deallocation(multiallocation_iterator(chain.get_it()));
         BOOST_RETHROW
      }
      BOOST_CATCH_END
   }

   void cached_deallocation(void *ptr)
   {
      //Check if cache is full
      if(m_cached_nodes.size() >= m_max_cached_nodes){
         //This only occurs if this allocator deallocate memory allocated
         //with other equal allocator. Since the cache is full, and more 
         //deallocations are probably coming, we'll make some room in cache
         //in a single, efficient multi node deallocation.
         this->priv_deallocate_n_nodes(m_cached_nodes.size() - m_max_cached_nodes/2);
      }
      m_cached_nodes.push_front(ptr);
   }

   void cached_deallocation(multiallocation_iterator it)
   {
      multiallocation_iterator itend;

      while(it != itend){
         void *addr = &*it;
         ++it;
         m_cached_nodes.push_front(addr);
      }

      //Check if cache is full
      if(m_cached_nodes.size() >= m_max_cached_nodes){
         //This only occurs if this allocator deallocate memory allocated
         //with other equal allocator. Since the cache is full, and more 
         //deallocations are probably coming, we'll make some room in cache
         //in a single, efficient multi node deallocation.
         this->priv_deallocate_n_nodes(m_cached_nodes.size() - m_max_cached_nodes/2);
      }
   }

   //!Sets the new max cached nodes value. This can provoke deallocations
   //!if "newmax" is less than current cached nodes. Never throws
   void set_max_cached_nodes(std::size_t newmax)
   {
      m_max_cached_nodes = newmax;
      this->priv_deallocate_remaining_nodes();
   }

   //!Frees all cached nodes.
   //!Never throws
   void deallocate_all_cached_nodes()
   {
      if(m_cached_nodes.empty()) return;
      mp_node_pool->deallocate_nodes(m_cached_nodes);
   }

   private:
   //!Frees all cached nodes at once.
   //!Never throws
   void priv_deallocate_remaining_nodes()
   {
      if(m_cached_nodes.size() > m_max_cached_nodes){
         priv_deallocate_n_nodes(m_cached_nodes.size()-m_max_cached_nodes);
      }
   }

   //!Frees n cached nodes at once. Never throws
   void priv_deallocate_n_nodes(std::size_t n)
   {
      //Deallocate all new linked list at once
      mp_node_pool->deallocate_nodes(m_cached_nodes, n);
   }
};

template<class Derived, class T, class SegmentManager>
class array_allocation_impl
{
   const Derived *derived() const
   {  return static_cast<const Derived*>(this); }
   Derived *derived()
   {  return static_cast<Derived*>(this); }

   typedef typename SegmentManager::void_pointer         void_pointer;

   public:
   typedef typename detail::
      pointer_to_other<void_pointer, T>::type            pointer;
   typedef typename detail::
      pointer_to_other<void_pointer, const T>::type      const_pointer;
   typedef T                                             value_type;
   typedef typename detail::add_reference
                     <value_type>::type                  reference;
   typedef typename detail::add_reference
                     <const value_type>::type            const_reference;
   typedef std::size_t                                   size_type;
   typedef std::ptrdiff_t                                difference_type;
   typedef transform_iterator
      < typename SegmentManager::
         multiallocation_iterator
      , detail::cast_functor <T> >          multiallocation_iterator;
   typedef typename SegmentManager::
      multiallocation_chain                 multiallocation_chain;

   public:
   //!Returns maximum the number of objects the previously allocated memory
   //!pointed by p can hold. This size only works for memory allocated with
   //!allocate, allocation_command and allocate_many.
   size_type size(const pointer &p) const
   {  
      return (size_type)this->derived()->get_segment_manager()->size(detail::get_pointer(p))/sizeof(T);
   }

   std::pair<pointer, bool>
      allocation_command(allocation_type command,
                         size_type limit_size, 
                         size_type preferred_size,
                         size_type &received_size, const pointer &reuse = 0)
   {
      return this->derived()->get_segment_manager()->allocation_command
         (command, limit_size, preferred_size, received_size, detail::get_pointer(reuse));
   }

   //!Allocates many elements of size elem_size in a contiguous block
   //!of memory. The minimum number to be allocated is min_elements,
   //!the preferred and maximum number is
   //!preferred_elements. The number of actually allocated elements is
   //!will be assigned to received_size. The elements must be deallocated
   //!with deallocate(...)
   multiallocation_iterator allocate_many(size_type elem_size, std::size_t num_elements)
   {
      return multiallocation_iterator
         (this->derived()->get_segment_manager()->allocate_many(sizeof(T)*elem_size, num_elements));
   }

   //!Allocates n_elements elements, each one of size elem_sizes[i]in a
   //!contiguous block
   //!of memory. The elements must be deallocated
   multiallocation_iterator allocate_many(const size_type *elem_sizes, size_type n_elements)
   {
      return multiallocation_iterator
         (this->derived()->get_segment_manager()->allocate_many(elem_sizes, n_elements, sizeof(T)));
   }

   //!Allocates many elements of size elem_size in a contiguous block
   //!of memory. The minimum number to be allocated is min_elements,
   //!the preferred and maximum number is
   //!preferred_elements. The number of actually allocated elements is
   //!will be assigned to received_size. The elements must be deallocated
   //!with deallocate(...)
   void deallocate_many(multiallocation_iterator it)
   {  return this->derived()->get_segment_manager()->deallocate_many(it.base()); }

   //!Returns the number of elements that could be
   //!allocated. Never throws
   size_type max_size() const
   {  return this->derived()->get_segment_manager()->get_size()/sizeof(T);  }

   //!Returns address of mutable object.
   //!Never throws
   pointer address(reference value) const
   {  return pointer(boost::addressof(value));  }

   //!Returns address of non mutable object.
   //!Never throws
   const_pointer address(const_reference value) const
   {  return const_pointer(boost::addressof(value));  }

   //!Default construct an object. 
   //!Throws if T's default constructor throws
   void construct(const pointer &ptr)
   {  new((void*)detail::get_pointer(ptr)) value_type;  }

   //!Copy construct an object
   //!Throws if T's copy constructor throws
   void construct(const pointer &ptr, const_reference v)
   {  new((void*)detail::get_pointer(ptr)) value_type(v);  }

   //!Destroys object. Throws if object's
   //!destructor throws
   void destroy(const pointer &ptr)
   {  BOOST_ASSERT(ptr != 0); (*ptr).~value_type();  }
};


template<class Derived, unsigned int Version, class T, class SegmentManager>
class node_pool_allocation_impl
   :  public array_allocation_impl
      < Derived
      , T
      , SegmentManager>
{
   const Derived *derived() const
   {  return static_cast<const Derived*>(this); }
   Derived *derived()
   {  return static_cast<Derived*>(this); }

   typedef typename SegmentManager::void_pointer         void_pointer;
   typedef typename detail::
      pointer_to_other<void_pointer, const void>::type   cvoid_pointer;

   public:
   typedef typename detail::
      pointer_to_other<void_pointer, T>::type            pointer;
   typedef typename detail::
      pointer_to_other<void_pointer, const T>::type      const_pointer;
   typedef T                                             value_type;
   typedef typename detail::add_reference
                     <value_type>::type                  reference;
   typedef typename detail::add_reference
                     <const value_type>::type            const_reference;
   typedef std::size_t                                   size_type;
   typedef std::ptrdiff_t                                difference_type;
   typedef transform_iterator
      < typename SegmentManager::
         multiallocation_iterator
      , detail::cast_functor <T> >          multiallocation_iterator;
   typedef typename SegmentManager::
      multiallocation_chain                 multiallocation_chain;

   template <int Dummy>
   struct node_pool
   {
      typedef typename Derived::template node_pool<0>::type type;
      static type *get(void *p)
      {  return static_cast<type*>(p); }
   };

   public:
   //!Allocate memory for an array of count elements. 
   //!Throws boost::interprocess::bad_alloc if there is no enough memory
   pointer allocate(size_type count, cvoid_pointer hint = 0)
   {
      (void)hint;
      typedef typename node_pool<0>::type node_pool_t;
      node_pool_t *pool = node_pool<0>::get(this->derived()->get_node_pool());