boost/interprocess/mem_algo/detail/mem_algo_common.hpp
////////////////////////////////////////////////////////////////////////////// // // (C) Copyright Ion Gaztanaga 2005-2012. 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_MEM_ALGO_COMMON_HPP #define BOOST_INTERPROCESS_DETAIL_MEM_ALGO_COMMON_HPP #ifndef BOOST_CONFIG_HPP # include <boost/config.hpp> #endif # #if defined(BOOST_HAS_PRAGMA_ONCE) # pragma once #endif #include <boost/interprocess/detail/config_begin.hpp> #include <boost/interprocess/detail/workaround.hpp> // interprocess #include <boost/interprocess/interprocess_fwd.hpp> #include <boost/interprocess/containers/allocation_type.hpp> // interprocess/detail #include <boost/interprocess/detail/math_functions.hpp> #include <boost/interprocess/detail/min_max.hpp> #include <boost/interprocess/detail/type_traits.hpp> #include <boost/interprocess/detail/utilities.hpp> // container/detail #include <boost/container/detail/multiallocation_chain.hpp> #include <boost/container/detail/placement_new.hpp> // move #include <boost/move/utility_core.hpp> // other boost #include <boost/static_assert.hpp> #include <boost/assert.hpp> //!\file //!Implements common operations for memory algorithms. namespace boost { namespace interprocess { namespace ipcdetail { template<class VoidPointer> class basic_multiallocation_chain : public boost::container::dtl:: basic_multiallocation_chain<VoidPointer> { BOOST_MOVABLE_BUT_NOT_COPYABLE(basic_multiallocation_chain) typedef boost::container::dtl:: basic_multiallocation_chain<VoidPointer> base_t; public: basic_multiallocation_chain() : base_t() {} basic_multiallocation_chain(BOOST_RV_REF(basic_multiallocation_chain) other) : base_t(::boost::move(static_cast<base_t&>(other))) {} basic_multiallocation_chain& operator=(BOOST_RV_REF(basic_multiallocation_chain) other) { this->base_t::operator=(::boost::move(static_cast<base_t&>(other))); return *this; } void *pop_front() { return boost::interprocess::ipcdetail::to_raw_pointer(this->base_t::pop_front()); } }; //!This class implements several allocation functions shared by different algorithms //!(aligned allocation, multiple allocation...). template<class MemoryAlgorithm> class memory_algorithm_common { public: typedef typename MemoryAlgorithm::void_pointer void_pointer; typedef typename MemoryAlgorithm::block_ctrl block_ctrl; typedef typename MemoryAlgorithm::multiallocation_chain multiallocation_chain; typedef memory_algorithm_common<MemoryAlgorithm> this_type; typedef typename MemoryAlgorithm::size_type size_type; static const size_type Alignment = MemoryAlgorithm::Alignment; static const size_type MinBlockUnits = MemoryAlgorithm::MinBlockUnits; static const size_type AllocatedCtrlBytes = MemoryAlgorithm::AllocatedCtrlBytes; static const size_type AllocatedCtrlUnits = MemoryAlgorithm::AllocatedCtrlUnits; static const size_type BlockCtrlBytes = MemoryAlgorithm::BlockCtrlBytes; static const size_type BlockCtrlUnits = MemoryAlgorithm::BlockCtrlUnits; static const size_type UsableByPreviousChunk = MemoryAlgorithm::UsableByPreviousChunk; static void assert_alignment(const void *ptr) { assert_alignment((std::size_t)ptr); } static void assert_alignment(size_type uint_ptr) { (void)uint_ptr; BOOST_ASSERT(uint_ptr % Alignment == 0); } static bool check_alignment(const void *ptr) { return (((std::size_t)ptr) % Alignment == 0); } static size_type ceil_units(size_type size) { return get_rounded_size(size, Alignment)/Alignment; } static size_type floor_units(size_type size) { return size/Alignment; } static size_type multiple_of_units(size_type size) { return get_rounded_size(size, Alignment); } static void allocate_many (MemoryAlgorithm *memory_algo, size_type elem_bytes, size_type n_elements, multiallocation_chain &chain) { return this_type::priv_allocate_many(memory_algo, &elem_bytes, n_elements, 0, chain); } static void deallocate_many(MemoryAlgorithm *memory_algo, multiallocation_chain &chain) { return this_type::priv_deallocate_many(memory_algo, chain); } static bool calculate_lcm_and_needs_backwards_lcmed (size_type backwards_multiple, size_type received_size, size_type size_to_achieve, size_type &lcm_out, size_type &needs_backwards_lcmed_out) { // Now calculate lcm_val size_type max = backwards_multiple; size_type min = Alignment; size_type needs_backwards; size_type needs_backwards_lcmed; size_type lcm_val; size_type current_forward; //Swap if necessary if(max < min){ size_type tmp = min; min = max; max = tmp; } //Check if it's power of two if((backwards_multiple & (backwards_multiple-1)) == 0){ if(0 != (size_to_achieve & ((backwards_multiple-1)))){ return false; } lcm_val = max; //If we want to use minbytes data to get a buffer between maxbytes //and minbytes if maxbytes can't be achieved, calculate the //biggest of all possibilities current_forward = get_truncated_size_po2(received_size, backwards_multiple); needs_backwards = size_to_achieve - current_forward; BOOST_ASSERT((needs_backwards % backwards_multiple) == 0); needs_backwards_lcmed = get_rounded_size_po2(needs_backwards, lcm_val); lcm_out = lcm_val; needs_backwards_lcmed_out = needs_backwards_lcmed; return true; } //Check if it's multiple of alignment else if((backwards_multiple & (Alignment - 1u)) == 0){ lcm_val = backwards_multiple; current_forward = get_truncated_size(received_size, backwards_multiple); //No need to round needs_backwards because backwards_multiple == lcm_val needs_backwards_lcmed = needs_backwards = size_to_achieve - current_forward; BOOST_ASSERT((needs_backwards_lcmed & (Alignment - 1u)) == 0); lcm_out = lcm_val; needs_backwards_lcmed_out = needs_backwards_lcmed; return true; } //Check if it's multiple of the half of the alignmment else if((backwards_multiple & ((Alignment/2u) - 1u)) == 0){ lcm_val = backwards_multiple*2u; current_forward = get_truncated_size(received_size, backwards_multiple); needs_backwards_lcmed = needs_backwards = size_to_achieve - current_forward; if(0 != (needs_backwards_lcmed & (Alignment-1))) //while(0 != (needs_backwards_lcmed & (Alignment-1))) needs_backwards_lcmed += backwards_multiple; BOOST_ASSERT((needs_backwards_lcmed % lcm_val) == 0); lcm_out = lcm_val; needs_backwards_lcmed_out = needs_backwards_lcmed; return true; } //Check if it's multiple of the quarter of the alignmment else if((backwards_multiple & ((Alignment/4u) - 1u)) == 0){ size_type remainder; lcm_val = backwards_multiple*4u; current_forward = get_truncated_size(received_size, backwards_multiple); needs_backwards_lcmed = needs_backwards = size_to_achieve - current_forward; //while(0 != (needs_backwards_lcmed & (Alignment-1))) //needs_backwards_lcmed += backwards_multiple; if(0 != (remainder = ((needs_backwards_lcmed & (Alignment-1))>>(Alignment/8u)))){ if(backwards_multiple & Alignment/2u){ needs_backwards_lcmed += (remainder)*backwards_multiple; } else{ needs_backwards_lcmed += (4-remainder)*backwards_multiple; } } BOOST_ASSERT((needs_backwards_lcmed % lcm_val) == 0); lcm_out = lcm_val; needs_backwards_lcmed_out = needs_backwards_lcmed; return true; } else{ lcm_val = lcm(max, min); } //If we want to use minbytes data to get a buffer between maxbytes //and minbytes if maxbytes can't be achieved, calculate the //biggest of all possibilities current_forward = get_truncated_size(received_size, backwards_multiple); needs_backwards = size_to_achieve - current_forward; BOOST_ASSERT((needs_backwards % backwards_multiple) == 0); needs_backwards_lcmed = get_rounded_size(needs_backwards, lcm_val); lcm_out = lcm_val; needs_backwards_lcmed_out = needs_backwards_lcmed; return true; } static void allocate_many ( MemoryAlgorithm *memory_algo , const size_type *elem_sizes , size_type n_elements , size_type sizeof_element , multiallocation_chain &chain) { this_type::priv_allocate_many(memory_algo, elem_sizes, n_elements, sizeof_element, chain); } static void* allocate_aligned (MemoryAlgorithm *memory_algo, size_type nbytes, size_type alignment) { //Ensure power of 2 if ((alignment & (alignment - size_type(1u))) != 0){ //Alignment is not power of two BOOST_ASSERT((alignment & (alignment - size_type(1u))) == 0); return 0; } size_type real_size = nbytes; if(alignment <= Alignment){ void *ignore_reuse = 0; return memory_algo->priv_allocate (boost::interprocess::allocate_new, nbytes, real_size, ignore_reuse); } if(nbytes > UsableByPreviousChunk) nbytes -= UsableByPreviousChunk; //We can find a aligned portion if we allocate a block that has alignment //nbytes + alignment bytes or more. size_type minimum_allocation = max_value (nbytes + alignment, size_type(MinBlockUnits*Alignment)); //Since we will split that block, we must request a bit more memory //if the alignment is near the beginning of the buffer, because otherwise, //there is no space for a new block before the alignment. // // ____ Aligned here // | // ----------------------------------------------------- // | MBU | // ----------------------------------------------------- size_type request = minimum_allocation + (2*MinBlockUnits*Alignment - AllocatedCtrlBytes //prevsize - UsableByPreviousChunk ); //Now allocate the buffer real_size = request; void *ignore_reuse = 0; void *buffer = memory_algo->priv_allocate(boost::interprocess::allocate_new, request, real_size, ignore_reuse); if(!buffer){ return 0; } else if ((((std::size_t)(buffer)) % alignment) == 0){ //If we are lucky and the buffer is aligned, just split it and //return the high part block_ctrl *first = memory_algo->priv_get_block(buffer); size_type old_size = first->m_size; const size_type first_min_units = max_value(ceil_units(nbytes) + AllocatedCtrlUnits, size_type(MinBlockUnits)); //We can create a new block in the end of the segment if(old_size >= (first_min_units + MinBlockUnits)){ block_ctrl *second = reinterpret_cast<block_ctrl *> (reinterpret_cast<char*>(first) + Alignment*first_min_units); first->m_size = first_min_units; second->m_size = old_size - first->m_size; BOOST_ASSERT(second->m_size >= MinBlockUnits); memory_algo->priv_mark_new_allocated_block(first); memory_algo->priv_mark_new_allocated_block(second); memory_algo->priv_deallocate(memory_algo->priv_get_user_buffer(second)); } return buffer; } //Buffer not aligned, find the aligned part. // // ____ Aligned here // | // ----------------------------------------------------- // | MBU +more | ACB | // ----------------------------------------------------- char *pos = reinterpret_cast<char*> (reinterpret_cast<std::size_t>(static_cast<char*>(buffer) + //This is the minimum size of (2) (MinBlockUnits*Alignment - AllocatedCtrlBytes) + //This is the next MBU for the aligned memory AllocatedCtrlBytes + //This is the alignment trick alignment - 1) & -alignment); //Now obtain the address of the blocks block_ctrl *first = memory_algo->priv_get_block(buffer); block_ctrl *second = memory_algo->priv_get_block(pos); BOOST_ASSERT(pos <= (reinterpret_cast<char*>(first) + first->m_size*Alignment)); BOOST_ASSERT(first->m_size >= 2*MinBlockUnits); BOOST_ASSERT((pos + MinBlockUnits*Alignment - AllocatedCtrlBytes + nbytes*Alignment/Alignment) <= (reinterpret_cast<char*>(first) + first->m_size*Alignment)); //Set the new size of the first block size_type old_size = first->m_size; first->m_size = (size_type)(reinterpret_cast<char*>(second) - reinterpret_cast<char*>(first))/Alignment; memory_algo->priv_mark_new_allocated_block(first); //Now check if we can create a new buffer in the end // // __"second" block // | __Aligned here // | | __"third" block // -----------|-----|-----|------------------------------ // | MBU +more | ACB | (3) | BCU | // ----------------------------------------------------- //This size will be the minimum size to be able to create a //new block in the end. const size_type second_min_units = max_value(size_type(MinBlockUnits), ceil_units(nbytes) + AllocatedCtrlUnits ); //Check if we can create a new block (of size MinBlockUnits) in the end of the segment if((old_size - first->m_size) >= (second_min_units + MinBlockUnits)){ //Now obtain the address of the end block block_ctrl *third = new (reinterpret_cast<char*>(second) + Alignment*second_min_units)block_ctrl; second->m_size = second_min_units; third->m_size = old_size - first->m_size - second->m_size; BOOST_ASSERT(third->m_size >= MinBlockUnits); memory_algo->priv_mark_new_allocated_block(second); memory_algo->priv_mark_new_allocated_block(third); memory_algo->priv_deallocate(memory_algo->priv_get_user_buffer(third)); } else{ second->m_size = old_size - first->m_size; BOOST_ASSERT(second->m_size >= MinBlockUnits); memory_algo->priv_mark_new_allocated_block(second); } memory_algo->priv_deallocate(memory_algo->priv_get_user_buffer(first)); return memory_algo->priv_get_user_buffer(second); } static bool try_shrink (MemoryAlgorithm *memory_algo, void *ptr ,const size_type max_size, size_type &received_size) { size_type const preferred_size = received_size; (void)memory_algo; //Obtain the real block block_ctrl *block = memory_algo->priv_get_block(ptr); size_type old_block_units = (size_type)block->m_size; //The block must be marked as allocated BOOST_ASSERT(memory_algo->priv_is_allocated_block(block)); //Check if alignment and block size are right assert_alignment(ptr); //Put this to a safe value received_size = (old_block_units - AllocatedCtrlUnits)*Alignment + UsableByPreviousChunk; //Now translate it to Alignment units const size_type max_user_units = floor_units(max_size - UsableByPreviousChunk); const size_type preferred_user_units = ceil_units(preferred_size - UsableByPreviousChunk); //Check if rounded max and preferred are possible correct if(max_user_units < preferred_user_units) return false; //Check if the block is smaller than the requested minimum size_type old_user_units = old_block_units - AllocatedCtrlUnits; if(old_user_units < preferred_user_units) return false; //If the block is smaller than the requested minimum if(old_user_units == preferred_user_units) return true; size_type shrunk_user_units = ((BlockCtrlUnits - AllocatedCtrlUnits) >= preferred_user_units) ? (BlockCtrlUnits - AllocatedCtrlUnits) : preferred_user_units; //Some parameter checks if(max_user_units < shrunk_user_units) return false; //We must be able to create at least a new empty block if((old_user_units - shrunk_user_units) < BlockCtrlUnits ){ return false; } //Update new size received_size = shrunk_user_units*Alignment + UsableByPreviousChunk; return true; } static bool shrink (MemoryAlgorithm *memory_algo, void *ptr ,const size_type max_size, size_type &received_size) { size_type const preferred_size = received_size; //Obtain the real block block_ctrl *block = memory_algo->priv_get_block(ptr); size_type old_block_units = (size_type)block->m_size; if(!try_shrink(memory_algo, ptr, max_size, received_size)){ return false; } //Check if the old size was just the shrunk size (no splitting) if((old_block_units - AllocatedCtrlUnits) == ceil_units(preferred_size - UsableByPreviousChunk)) return true; //Now we can just rewrite the size of the old buffer block->m_size = (received_size-UsableByPreviousChunk)/Alignment + AllocatedCtrlUnits; BOOST_ASSERT(block->m_size >= BlockCtrlUnits); //We create the new block block_ctrl *new_block = reinterpret_cast<block_ctrl*> (reinterpret_cast<char*>(block) + block->m_size*Alignment); //Write control data to simulate this new block was previously allocated //and deallocate it new_block->m_size = old_block_units - block->m_size; BOOST_ASSERT(new_block->m_size >= BlockCtrlUnits); memory_algo->priv_mark_new_allocated_block(block); memory_algo->priv_mark_new_allocated_block(new_block); memory_algo->priv_deallocate(memory_algo->priv_get_user_buffer(new_block)); return true; } private: static void priv_allocate_many ( MemoryAlgorithm *memory_algo , const size_type *elem_sizes , size_type n_elements , size_type sizeof_element , multiallocation_chain &chain) { //Note: sizeof_element == 0 indicates that we want to //allocate n_elements of the same size "*elem_sizes" //Calculate the total size of all requests size_type total_request_units = 0; size_type elem_units = 0; const size_type ptr_size_units = memory_algo->priv_get_total_units(sizeof(void_pointer)); if(!sizeof_element){ elem_units = memory_algo->priv_get_total_units(*elem_sizes); elem_units = ptr_size_units > elem_units ? ptr_size_units : elem_units; total_request_units = n_elements*elem_units; } else{ for(size_type i = 0; i < n_elements; ++i){ if(multiplication_overflows(elem_sizes[i], sizeof_element)){ total_request_units = 0; break; } elem_units = memory_algo->priv_get_total_units(elem_sizes[i]*sizeof_element); elem_units = ptr_size_units > elem_units ? ptr_size_units : elem_units; if(sum_overflows(total_request_units, elem_units)){ total_request_units = 0; break; } total_request_units += elem_units; } } if(total_request_units && !multiplication_overflows(total_request_units, Alignment)){ size_type low_idx = 0; while(low_idx < n_elements){ size_type total_bytes = total_request_units*Alignment - AllocatedCtrlBytes + UsableByPreviousChunk; size_type min_allocation = (!sizeof_element) ? elem_units : memory_algo->priv_get_total_units(elem_sizes[low_idx]*sizeof_element); min_allocation = min_allocation*Alignment - AllocatedCtrlBytes + UsableByPreviousChunk; size_type received_size = total_bytes; void *ignore_reuse = 0; void *ret = memory_algo->priv_allocate (boost::interprocess::allocate_new, min_allocation, received_size, ignore_reuse); if(!ret){ break; } block_ctrl *block = memory_algo->priv_get_block(ret); size_type received_units = (size_type)block->m_size; char *block_address = reinterpret_cast<char*>(block); size_type total_used_units = 0; while(total_used_units < received_units){ if(sizeof_element){ elem_units = memory_algo->priv_get_total_units(elem_sizes[low_idx]*sizeof_element); elem_units = ptr_size_units > elem_units ? ptr_size_units : elem_units; } if(total_used_units + elem_units > received_units) break; total_request_units -= elem_units; //This is the position where the new block must be created block_ctrl *new_block = reinterpret_cast<block_ctrl *>(block_address); assert_alignment(new_block); //The last block should take all the remaining space if((low_idx + 1) == n_elements || (total_used_units + elem_units + ((!sizeof_element) ? elem_units : max_value(memory_algo->priv_get_total_units(elem_sizes[low_idx+1]*sizeof_element), ptr_size_units)) > received_units)){ //By default, the new block will use the rest of the buffer new_block->m_size = received_units - total_used_units; memory_algo->priv_mark_new_allocated_block(new_block); //If the remaining units are bigger than needed and we can //split it obtaining a new free memory block do it. if((received_units - total_used_units) >= (elem_units + MemoryAlgorithm::BlockCtrlUnits)){ size_type shrunk_request = elem_units*Alignment - AllocatedCtrlBytes + UsableByPreviousChunk; size_type shrunk_received = shrunk_request; bool shrink_ok = shrink (memory_algo ,memory_algo->priv_get_user_buffer(new_block) ,shrunk_request ,shrunk_received); (void)shrink_ok; //Shrink must always succeed with passed parameters BOOST_ASSERT(shrink_ok); //Some sanity checks BOOST_ASSERT(shrunk_request == shrunk_received); BOOST_ASSERT(elem_units == ((shrunk_request-UsableByPreviousChunk)/Alignment + AllocatedCtrlUnits)); //"new_block->m_size" must have been reduced to elem_units by "shrink" BOOST_ASSERT(new_block->m_size == elem_units); //Now update the total received units with the reduction received_units = elem_units + total_used_units; } } else{ new_block->m_size = elem_units; memory_algo->priv_mark_new_allocated_block(new_block); } block_address += new_block->m_size*Alignment; total_used_units += (size_type)new_block->m_size; //Check we have enough room to overwrite the intrusive pointer BOOST_ASSERT((new_block->m_size*Alignment - AllocatedCtrlUnits) >= sizeof(void_pointer)); void_pointer p = ::new(memory_algo->priv_get_user_buffer(new_block), boost_container_new_t())void_pointer(0); chain.push_back(p); ++low_idx; } //Sanity check BOOST_ASSERT(total_used_units == received_units); } if(low_idx != n_elements){ priv_deallocate_many(memory_algo, chain); } } } static void priv_deallocate_many(MemoryAlgorithm *memory_algo, multiallocation_chain &chain) { while(!chain.empty()){ memory_algo->priv_deallocate(to_raw_pointer(chain.pop_front())); } } }; } //namespace ipcdetail { } //namespace interprocess { } //namespace boost { #include <boost/interprocess/detail/config_end.hpp> #endif //#ifndef BOOST_INTERPROCESS_DETAIL_MEM_ALGO_COMMON_HPP