boost/interprocess/mem_algo/detail/mem_algo_common.hpp
//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2008. 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_MEM_ALGO_COMMON_HPP
#define BOOST_INTERPROCESS_DETAIL_MEM_ALGO_COMMON_HPP
#if (defined _MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif
#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>
#include <boost/interprocess/interprocess_fwd.hpp>
#include <boost/interprocess/allocators/allocation_type.hpp>
#include <boost/interprocess/detail/utilities.hpp>
#include <boost/interprocess/detail/type_traits.hpp>
#include <boost/interprocess/detail/iterators.hpp>
#include <boost/interprocess/detail/math_functions.hpp>
#include <boost/interprocess/detail/utilities.hpp>
#include <boost/assert.hpp>
#include <boost/static_assert.hpp>
//!\file
//!Implements common operations for memory algorithms.
namespace boost {
namespace interprocess {
namespace detail {
template<class VoidPointer>
struct multi_allocation_next
{
typedef typename detail::
pointer_to_other<VoidPointer, multi_allocation_next>::type
multi_allocation_next_ptr;
multi_allocation_next(multi_allocation_next_ptr n)
: next_(n)
{}
multi_allocation_next_ptr next_;
};
//!This iterator is returned by "allocate_many" functions so that
//!the user can access the multiple buffers allocated in a single call
template<class VoidPointer>
class basic_multiallocation_iterator
: public std::iterator<std::input_iterator_tag, char>
{
void unspecified_bool_type_func() const {}
typedef void (basic_multiallocation_iterator::*unspecified_bool_type)() const;
typedef typename detail::
pointer_to_other
<VoidPointer, multi_allocation_next<VoidPointer> >::type
multi_allocation_next_ptr;
public:
typedef char value_type;
typedef value_type & reference;
typedef value_type * pointer;
basic_multiallocation_iterator()
: next_alloc_(0)
{}
basic_multiallocation_iterator(multi_allocation_next_ptr next)
: next_alloc_(next)
{}
basic_multiallocation_iterator &operator=(const basic_multiallocation_iterator &other)
{ next_alloc_ = other.next_alloc_; return *this; }
public:
basic_multiallocation_iterator& operator++()
{ next_alloc_.next_ = detail::get_pointer(next_alloc_.next_->next_); return *this; }
basic_multiallocation_iterator operator++(int)
{
basic_multiallocation_iterator result(next_alloc_.next_);
++*this;
return result;
}
bool operator== (const basic_multiallocation_iterator& other) const
{ return next_alloc_.next_ == other.next_alloc_.next_; }
bool operator!= (const basic_multiallocation_iterator& other) const
{ return !operator== (other); }
reference operator*() const
{ return *reinterpret_cast<char*>(detail::get_pointer(next_alloc_.next_)); }
operator unspecified_bool_type() const
{ return next_alloc_.next_? &basic_multiallocation_iterator::unspecified_bool_type_func : 0; }
pointer operator->() const
{ return &(*(*this)); }
static basic_multiallocation_iterator create_simple_range(void *mem)
{
basic_multiallocation_iterator it;
typedef multi_allocation_next<VoidPointer> next_impl_t;
next_impl_t * tmp_mem = static_cast<next_impl_t*>(mem);
it = basic_multiallocation_iterator<VoidPointer>(tmp_mem);
tmp_mem->next_ = 0;
return it;
}
multi_allocation_next<VoidPointer> &get_multi_allocation_next()
{ return *next_alloc_.next_; }
private:
multi_allocation_next<VoidPointer> next_alloc_;
};
template<class VoidPointer>
class basic_multiallocation_chain
{
private:
basic_multiallocation_iterator<VoidPointer> it_;
VoidPointer last_mem_;
std::size_t num_mem_;
basic_multiallocation_chain(const basic_multiallocation_chain &);
basic_multiallocation_chain &operator=(const basic_multiallocation_chain &);
public:
typedef basic_multiallocation_iterator<VoidPointer> multiallocation_iterator;
basic_multiallocation_chain()
: it_(0), last_mem_(0), num_mem_(0)
{}
void reset()
{
this->it_ = multiallocation_iterator();
this->last_mem_ = 0;
this->num_mem_ = 0;
}
void push_back(void *mem)
{
typedef multi_allocation_next<VoidPointer> next_impl_t;
next_impl_t * tmp_mem = static_cast<next_impl_t*>(mem);
if(!this->last_mem_){
this->it_ = basic_multiallocation_iterator<VoidPointer>(tmp_mem);
}
else{
static_cast<next_impl_t*>(detail::get_pointer(this->last_mem_))->next_ = tmp_mem;
}
tmp_mem->next_ = 0;
this->last_mem_ = tmp_mem;
++num_mem_;
}
void push_front(void *mem)
{
typedef multi_allocation_next<VoidPointer> next_impl_t;
next_impl_t * tmp_mem = static_cast<next_impl_t*>(mem);
++num_mem_;
if(!this->last_mem_){
this->it_ = basic_multiallocation_iterator<VoidPointer>(tmp_mem);
tmp_mem->next_ = 0;
this->last_mem_ = tmp_mem;
}
else{
next_impl_t * old_first = &this->it_.get_multi_allocation_next();
tmp_mem->next_ = old_first;
this->it_ = basic_multiallocation_iterator<VoidPointer>(tmp_mem);
}
}
void swap(basic_multiallocation_chain &other_chain)
{
std::swap(this->it_, other_chain.it_);
std::swap(this->last_mem_, other_chain.last_mem_);
std::swap(this->num_mem_, other_chain.num_mem_);
}
void splice_back(basic_multiallocation_chain &other_chain)
{
typedef multi_allocation_next<VoidPointer> next_impl_t;
multiallocation_iterator end_it;
multiallocation_iterator other_it = other_chain.get_it();
multiallocation_iterator this_it = this->get_it();
if(end_it == other_it){
return;
}
else if(end_it == this_it){
this->swap(other_chain);
}
else{
static_cast<next_impl_t*>(detail::get_pointer(this->last_mem_))->next_
= &other_chain.it_.get_multi_allocation_next();
this->last_mem_ = other_chain.last_mem_;
this->num_mem_ += other_chain.num_mem_;
}
}
void *pop_front()
{
multiallocation_iterator itend;
if(this->it_ == itend){
this->last_mem_= 0;
this->num_mem_ = 0;
return 0;
}
else{
void *addr = &*it_;
++it_;
--num_mem_;
if(!num_mem_){
this->last_mem_ = 0;
this->it_ = multiallocation_iterator();
}
return addr;
}
}
bool empty() const
{ return !num_mem_; }
multiallocation_iterator get_it() const
{ return it_; }
std::size_t size() const
{ return num_mem_; }
};
//!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_iterator multiallocation_iterator;
typedef multi_allocation_next<void_pointer> multi_allocation_next_t;
typedef typename multi_allocation_next_t::
multi_allocation_next_ptr multi_allocation_next_ptr;
typedef memory_algorithm_common<MemoryAlgorithm> this_type;
static const std::size_t Alignment = MemoryAlgorithm::Alignment;
static const std::size_t MinBlockUnits = MemoryAlgorithm::MinBlockUnits;
static const std::size_t AllocatedCtrlBytes = MemoryAlgorithm::AllocatedCtrlBytes;
static const std::size_t AllocatedCtrlUnits = MemoryAlgorithm::AllocatedCtrlUnits;
static const std::size_t BlockCtrlBytes = MemoryAlgorithm::BlockCtrlBytes;
static const std::size_t BlockCtrlUnits = MemoryAlgorithm::BlockCtrlUnits;
static const std::size_t UsableByPreviousChunk = MemoryAlgorithm::UsableByPreviousChunk;
static void assert_alignment(const void *ptr)
{ assert_alignment((std::size_t)ptr); }
static void assert_alignment(std::size_t 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 std::size_t ceil_units(std::size_t size)
{ return detail::get_rounded_size(size, Alignment)/Alignment; }
static std::size_t floor_units(std::size_t size)
{ return size/Alignment; }
static std::size_t multiple_of_units(std::size_t size)
{ return detail::get_rounded_size(size, Alignment); }
static multiallocation_iterator allocate_many
(MemoryAlgorithm *memory_algo, std::size_t elem_bytes, std::size_t n_elements)
{
return this_type::priv_allocate_many(memory_algo, &elem_bytes, n_elements, 0);
}
static bool calculate_lcm_and_needs_backwards_lcmed
(std::size_t backwards_multiple, std::size_t received_size, std::size_t size_to_achieve,
std::size_t &lcm_out, std::size_t &needs_backwards_lcmed_out)
{
// Now calculate lcm
std::size_t max = backwards_multiple;
std::size_t min = Alignment;
std::size_t needs_backwards;
std::size_t needs_backwards_lcmed;
std::size_t lcm;
std::size_t current_forward;
//Swap if necessary
if(max < min){
std::size_t 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 = 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 = detail::get_truncated_size_po2(received_size, backwards_multiple);
needs_backwards = size_to_achieve - current_forward;
assert((needs_backwards % backwards_multiple) == 0);
needs_backwards_lcmed = detail::get_rounded_size_po2(needs_backwards, lcm);
lcm_out = lcm;
needs_backwards_lcmed_out = needs_backwards_lcmed;
return true;
}
//Check if it's multiple of alignment
else if((backwards_multiple & (Alignment - 1u)) == 0){
lcm = backwards_multiple;
current_forward = detail::get_truncated_size(received_size, backwards_multiple);
//No need to round needs_backwards because backwards_multiple == lcm
needs_backwards_lcmed = needs_backwards = size_to_achieve - current_forward;
assert((needs_backwards_lcmed & (Alignment - 1u)) == 0);
lcm_out = lcm;
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 = backwards_multiple*2u;
current_forward = detail::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;
assert((needs_backwards_lcmed % lcm) == 0);
lcm_out = lcm;
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/4u) - 1u)) == 0){
std::size_t remainder;
lcm = backwards_multiple*4u;
current_forward = detail::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;
}
}
assert((needs_backwards_lcmed % lcm) == 0);
lcm_out = lcm;
needs_backwards_lcmed_out = needs_backwards_lcmed;
return true;
}
else{
lcm = detail::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 = detail::get_truncated_size(received_size, backwards_multiple);
needs_backwards = size_to_achieve - current_forward;
assert((needs_backwards % backwards_multiple) == 0);
needs_backwards_lcmed = detail::get_rounded_size(needs_backwards, lcm);
lcm_out = lcm;
needs_backwards_lcmed_out = needs_backwards_lcmed;
return true;
}
static multiallocation_iterator allocate_many
( MemoryAlgorithm *memory_algo
, const std::size_t *elem_sizes
, std::size_t n_elements
, std::size_t sizeof_element)
{
return this_type::priv_allocate_many(memory_algo, elem_sizes, n_elements, sizeof_element);
}
static void* allocate_aligned
(MemoryAlgorithm *memory_algo, std::size_t nbytes, std::size_t alignment)
{
//Ensure power of 2
if ((alignment & (alignment - std::size_t(1u))) != 0){
//Alignment is not power of two
BOOST_ASSERT((alignment & (alignment - std::size_t(1u))) == 0);
return 0;
}
std::size_t real_size;
if(alignment <= Alignment){
return memory_algo->priv_allocate(allocate_new, nbytes, nbytes, real_size).first;
}
if(nbytes > UsableByPreviousChunk)
nbytes -= UsableByPreviousChunk;
//We can find a aligned portion if we allocate a block that has alignment
//nbytes + alignment bytes or more.
std::size_t minimum_allocation = max_value
(nbytes + alignment, std::size_t(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 |
// -----------------------------------------------------
std::size_t request =
minimum_allocation + (2*MinBlockUnits*Alignment - AllocatedCtrlBytes
//prevsize - UsableByPreviousChunk
);
//Now allocate the buffer
void *buffer = memory_algo->priv_allocate(allocate_new, request, request, real_size).first;
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);
std::size_t old_size = first->m_size;
const std::size_t first_min_units =
max_value(ceil_units(nbytes) + AllocatedCtrlUnits, std::size_t(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_tail_size(first, first->m_size);
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);
assert(pos <= (reinterpret_cast<char*>(first) + first->m_size*Alignment));
assert(first->m_size >= 2*MinBlockUnits);
assert((pos + MinBlockUnits*Alignment - AllocatedCtrlBytes + nbytes*Alignment/Alignment) <=
(reinterpret_cast<char*>(first) + first->m_size*Alignment));
//Set the new size of the first block
std::size_t old_size = first->m_size;
first->m_size = (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 std::size_t second_min_units = max_value(std::size_t(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;
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 std::size_t max_size, const std::size_t preferred_size
,std::size_t &received_size)
{
(void)memory_algo;
//Obtain the real block
block_ctrl *block = memory_algo->priv_get_block(ptr);
std::size_t old_block_units = 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 std::size_t max_user_units = floor_units(max_size - UsableByPreviousChunk);
const std::size_t 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
std::size_t 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;
std::size_t 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 std::size_t max_size, const std::size_t preferred_size
,std::size_t &received_size)
{
//Obtain the real block
block_ctrl *block = memory_algo->priv_get_block(ptr);
std::size_t old_block_units = block->m_size;
if(!try_shrink
(memory_algo, ptr, max_size, preferred_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 multiallocation_iterator priv_allocate_many
( MemoryAlgorithm *memory_algo
, const std::size_t *elem_sizes
, std::size_t n_elements
, std::size_t sizeof_element)
{
//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
std::size_t total_request_units = 0;
std::size_t elem_units = 0;
const std::size_t ptr_size_units = memory_algo->priv_get_total_units(sizeof(multi_allocation_next_ptr));
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(std::size_t i = 0; i < n_elements; ++i){
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;
total_request_units += elem_units;
}
}
multi_allocation_next_ptr first = 0, previous = 0;
std::size_t low_idx = 0;
while(low_idx < n_elements){
std::size_t total_bytes = total_request_units*Alignment - AllocatedCtrlBytes + UsableByPreviousChunk;
std::size_t 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;
std::size_t received_size;
std::pair<void *, bool> ret = memory_algo->priv_allocate
(allocate_new, min_allocation, total_bytes, received_size, 0);
if(!ret.first){
break;
}
block_ctrl *block = memory_algo->priv_get_block(ret.first);
std::size_t received_units = block->m_size;
char *block_address = reinterpret_cast<char*>(block);
std::size_t total_used_units = 0;
// block_ctrl *prev_block = 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
: memory_algo->priv_get_total_units(elem_sizes[low_idx+1]*sizeof_element))
) > 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)){
std::size_t shrunk_received;
std::size_t shrunk_request = elem_units*Alignment - AllocatedCtrlBytes + UsableByPreviousChunk;
bool shrink_ok = shrink
(memory_algo
,memory_algo->priv_get_user_buffer(new_block)
,shrunk_request
,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 += new_block->m_size;
//Check we have enough room to overwrite the intrusive pointer
assert((new_block->m_size*Alignment - AllocatedCtrlUnits) >= sizeof(multi_allocation_next_t));
multi_allocation_next_ptr p = new(memory_algo->priv_get_user_buffer(new_block))multi_allocation_next_t(0);
if(!first){
first = p;
}
else{
previous->next_ = p;
}
previous = p;
++low_idx;
//prev_block = new_block;
}
//Sanity check
BOOST_ASSERT(total_used_units == received_units);
}
if(low_idx != n_elements){
while(first){
multi_allocation_next_ptr prev = first;
first = first->next_;
memory_algo->priv_deallocate(detail::get_pointer(prev));
}
return multiallocation_iterator();
}
else{
return multiallocation_iterator(first);
}
}
};
} //namespace detail {
} //namespace interprocess {
} //namespace boost {
#include <boost/interprocess/detail/config_end.hpp>
#endif //#ifndef BOOST_INTERPROCESS_DETAIL_MEM_ALGO_COMMON_HPP