multi_simple_seq_fit_impl.hpp

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   do{
      //Just clear user the memory part reserved for the user      
      std::memset( reinterpret_cast<char*>(block) + BlockCtrlBytes
                 , 0
                 , block->m_size*Alignment - BlockCtrlBytes);
      block = detail::get_pointer(block->m_next);
   }
   while(block != &m_header.m_root);
}

template<class MutexFamily, class VoidPointer>
inline bool simple_seq_fit_impl<MutexFamily, VoidPointer>::
    check_sanity()
{
   //-----------------------
   boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
   //-----------------------
   block_ctrl *block = detail::get_pointer(m_header.m_root.m_next);

   std::size_t free_memory = 0;

   //Iterate through all blocks obtaining their size
   do{
      //Free blocks's next must be always valid
      block_ctrl *next = detail::get_pointer(block->m_next);
      if(!next){
         return false;
      }
      free_memory += block->m_size*Alignment;
      block = next;
   }
   while(block != &m_header.m_root);

   //Check allocated bytes are less than size
   if(m_header.m_allocated > m_header.m_size){
      return false;
   }

   //Check free bytes are less than size
   if(free_memory > m_header.m_size){
      return false;
   }
   return true;
}

template<class MutexFamily, class VoidPointer>
inline void* simple_seq_fit_impl<MutexFamily, VoidPointer>::
   allocate(std::size_t nbytes)
{  
   //-----------------------
   boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
   //-----------------------
   std::size_t ignore;
   return priv_allocate(allocate_new, nbytes, nbytes, ignore).first;
}

template<class MutexFamily, class VoidPointer>
inline void* simple_seq_fit_impl<MutexFamily, VoidPointer>::
   allocate_aligned(std::size_t nbytes, std::size_t alignment)
{  
   //-----------------------
   boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
   //-----------------------
   return priv_allocate_aligned(nbytes, alignment);
}

template<class MutexFamily, class VoidPointer>
inline std::pair<void *, bool> simple_seq_fit_impl<MutexFamily, VoidPointer>::
   allocation_command  (allocation_type command,   std::size_t min_size,
                        std::size_t preferred_size,std::size_t &received_size, 
                        void *reuse_ptr, std::size_t backwards_multiple)
{
   //-----------------------
   boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
   //-----------------------
   (void)backwards_multiple;
   command &= ~expand_bwd;
   if(!command)
      return std::pair<void *, bool>(0, false);
   return priv_allocate(command, min_size, preferred_size, received_size, reuse_ptr);
}

template<class MutexFamily, class VoidPointer>
inline std::size_t simple_seq_fit_impl<MutexFamily, VoidPointer>::
   size(void *ptr) const
{
   //We need no synchronization since this block is not going
   //to be modified
   //Obtain the real size of the block
   block_ctrl *block = reinterpret_cast<block_ctrl*>
                        (reinterpret_cast<char*>(ptr) - BlockCtrlBytes);
   return block->m_size*Alignment - BlockCtrlBytes;
}

template<class MutexFamily, class VoidPointer>
inline void* simple_seq_fit_impl<MutexFamily, VoidPointer>::
   multi_allocate(std::size_t nbytes)
{
   //-----------------------
   boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
   //-----------------------
   //Multisegment pointer. Let's try first the normal allocation
   //since it's faster.
   std::size_t ignore;
   void *addr = this->priv_allocate(allocate_new, nbytes, nbytes, ignore).first;
   if(!addr){
      //If this fails we will try the allocation through the segment
      //creator.
      std::size_t group, id;
      //Obtain the segment group of this segment
      void_pointer::get_group_and_id(this, group, id);
      if(group == 0){
         //Ooops, group 0 is not valid.
         return 0;
      }
      //Now obtain the polymorphic functor that creates
      //new segments and try to allocate again.
      boost::interprocess::multi_segment_services *p_services = 
         static_cast<boost::interprocess::multi_segment_services*>
                     (void_pointer::find_group_data(group));
      assert(p_services);
      std::pair<void *, std::size_t> ret = 
         p_services->create_new_segment(MinBlockSize > nbytes ? MinBlockSize : nbytes);
      if(ret.first){
         priv_add_segment(ret.first, ret.second);
         addr = this->priv_allocate(allocate_new, nbytes, nbytes, ignore).first;
      }
   }
   return addr;
}

template<class MutexFamily, class VoidPointer>
void* simple_seq_fit_impl<MutexFamily, VoidPointer>::
   priv_expand_both_sides(allocation_type command
                         ,std::size_t min_size
                         ,std::size_t preferred_size
                         ,std::size_t &received_size
                         ,void *reuse_ptr
                         ,bool only_preferred_backwards)
{
   typedef std::pair<block_ctrl *, block_ctrl *> prev_block_t;
   block_ctrl *reuse = block_ctrl::get_block_from_addr(reuse_ptr);
   received_size = 0;

   if(this->size(reuse_ptr) > min_size){
      received_size = this->size(reuse_ptr);
      return reuse_ptr;
   }

   if(command & expand_fwd){
      if(priv_expand(reuse_ptr, min_size, preferred_size, received_size))
         return reuse_ptr;
   }
   else{
      received_size = this->size(reuse_ptr);
   }
   if(command & expand_bwd){
      std::size_t extra_forward = !received_size ? 0 : received_size + BlockCtrlBytes;
      prev_block_t prev_pair = priv_prev_block_if_free(reuse);
      block_ctrl *prev = prev_pair.second;
      if(!prev){
         return 0;
      }

      std::size_t needs_backwards = 
         detail::get_rounded_size(preferred_size - extra_forward, Alignment);
   
      if(!only_preferred_backwards){
         needs_backwards = 
            max_value(detail::get_rounded_size(min_size - extra_forward, Alignment)
                     ,min_value(prev->get_user_bytes(), needs_backwards));
      }

      //Check if previous block has enough size
      if((prev->get_user_bytes()) >=  needs_backwards){
         //Now take all next space. This will succeed
         if(!priv_expand(reuse_ptr, received_size, received_size, received_size)){
            assert(0);
         }
         
         //We need a minimum size to split the previous one
         if((prev->get_user_bytes() - needs_backwards) > 2*BlockCtrlBytes){
            block_ctrl *new_block = reinterpret_cast<block_ctrl *>
               (reinterpret_cast<char*>(reuse) - needs_backwards - BlockCtrlBytes);
            new_block->m_next = 0;
            new_block->m_size = 
               BlockCtrlSize + (needs_backwards + extra_forward)/Alignment;
            prev->m_size = 
               (prev->get_total_bytes() - needs_backwards)/Alignment - BlockCtrlSize;
            received_size = needs_backwards + extra_forward;
            m_header.m_allocated += needs_backwards + BlockCtrlBytes;
            return new_block->get_addr();
         }
         else{
            //Just merge the whole previous block
            block_ctrl *prev_2_block = prev_pair.first;
            //Update received size and allocation
            received_size = extra_forward + prev->get_user_bytes();
            m_header.m_allocated += prev->get_total_bytes();
            //Now unlink it from previous block
            prev_2_block->m_next = prev->m_next;
            prev->m_size = reuse->m_size + prev->m_size;
            prev->m_next = 0;
            return prev->get_addr();
         }
      }
   }
   return 0;
}

template<class MutexFamily, class VoidPointer>
std::pair<void *, bool> simple_seq_fit_impl<MutexFamily, VoidPointer>::
   priv_allocate(allocation_type command
                ,std::size_t limit_size
                ,std::size_t preferred_size
                ,std::size_t &received_size
                ,void *reuse_ptr)
{
   if(command & shrink_in_place){
      bool success = 
         this->priv_shrink(reuse_ptr, limit_size, preferred_size, received_size);
      return std::pair<void *, bool> ((success ? reuse_ptr : 0), true);
   }
   typedef std::pair<void *, bool> return_type;
   received_size = 0;

   if(limit_size > preferred_size)
      return return_type(0, false);

   //Number of units to request (including block_ctrl header)
   std::size_t nunits = detail::get_rounded_size(preferred_size, Alignment)/Alignment + BlockCtrlSize;

   //Get the root and the first memory block
   block_ctrl *prev                 = &m_header.m_root;
   block_ctrl *block                = detail::get_pointer(prev->m_next);
   block_ctrl *root                 = &m_header.m_root;
   block_ctrl *biggest_block        = 0;
   block_ctrl *prev_biggest_block   = 0;
   std::size_t biggest_size         = limit_size;

   //Expand in place
   //reuse_ptr, limit_size, preferred_size, received_size
   //
   if(reuse_ptr && (command & (expand_fwd | expand_bwd))){
      void *ret = priv_expand_both_sides
         (command, limit_size, preferred_size, received_size, reuse_ptr, true);
      if(ret)
         return return_type(ret, true);
   }

   if(command & allocate_new){
      received_size = 0;
      while(block != root){
         //Update biggest block pointers
         if(block->m_size > biggest_size){
            prev_biggest_block = prev;
            biggest_size  = block->m_size;
            biggest_block = block;
         }
         void *addr = this->priv_check_and_allocate(nunits, prev, block, received_size);
         if(addr) return return_type(addr, false);
         //Bad luck, let's check next block
         prev  = block;
         block = detail::get_pointer(block->m_next);
      }

      //Bad luck finding preferred_size, now if we have any biggest_block
      //try with this block
      if(biggest_block){
         received_size = biggest_block->m_size*Alignment - BlockCtrlSize;
         nunits = detail::get_rounded_size(limit_size, Alignment)/Alignment + BlockCtrlSize;
         void *ret = this->priv_check_and_allocate
                        (nunits, prev_biggest_block, biggest_block, received_size);
         if(ret)
            return return_type(ret, false);
      }
   }
   //Now try to expand both sides with min size
   if(reuse_ptr && (command & (expand_fwd | expand_bwd))){
      return return_type(priv_expand_both_sides
         (command, limit_size, preferred_size, received_size, reuse_ptr, false), true);
   }
   return return_type(0, false);
}

template<class MutexFamily, class VoidPointer>
inline typename simple_seq_fit_impl<MutexFamily, VoidPointer>::block_ctrl *
   simple_seq_fit_impl<MutexFamily, VoidPointer>::
      priv_next_block_if_free
         (typename simple_seq_fit_impl<MutexFamily, VoidPointer>::block_ctrl *ptr)
{
   //Take the address where the next block should go
   block_ctrl *next_block = reinterpret_cast<block_ctrl*>
      (reinterpret_cast<char*>(ptr) + ptr->m_size*Alignment);

   //Check if the adjacent block is in the managed segment
   std::size_t distance = (reinterpret_cast<char*>(next_block) - reinterpret_cast<char*>(this))/Alignment;
   if(distance >= (m_header.m_size/Alignment)){
      //"next_block" does not exist so we can't expand "block"
      return 0;
   }

   if(!next_block->m_next)
      return 0;

   return next_block;
}

template<class MutexFamily, class VoidPointer>
inline 
   std::pair<typename simple_seq_fit_impl<MutexFamily, VoidPointer>::block_ctrl *
            ,typename simple_seq_fit_impl<MutexFamily, VoidPointer>::block_ctrl *>
   simple_seq_fit_impl<MutexFamily, VoidPointer>::
      priv_prev_block_if_free
         (typename simple_seq_fit_impl<MutexFamily, VoidPointer>::block_ctrl *ptr)
{
   typedef std::pair<block_ctrl *, block_ctrl *> prev_pair_t;
   //Take the address where the previous block should go
   block_ctrl *root           = &m_header.m_root;
   block_ctrl *prev_2_block   = root;
   block_ctrl *prev_block = detail::get_pointer(root->m_next);
   while((reinterpret_cast<char*>(prev_block) + prev_block->m_size*Alignment)
            != (reinterpret_cast<char*>(ptr))
         && prev_block != root){