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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2011. 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_MEM_ALGO_DETAIL_SIMPLE_SEQ_FIT_IMPL_HPP
#define BOOST_INTERPROCESS_MEM_ALGO_DETAIL_SIMPLE_SEQ_FIT_IMPL_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/intrusive/pointer_traits.hpp>
#include <boost/interprocess/interprocess_fwd.hpp>
#include <boost/interprocess/containers/allocation_type.hpp>
#include <boost/interprocess/offset_ptr.hpp>
#include <boost/interprocess/sync/interprocess_mutex.hpp>
#include <boost/interprocess/exceptions.hpp>
#include <boost/interprocess/detail/utilities.hpp>
#include <boost/interprocess/detail/multi_segment_services.hpp>
#include <boost/type_traits/alignment_of.hpp>
#include <boost/type_traits/type_with_alignment.hpp>
#include <boost/interprocess/detail/min_max.hpp>
#include <boost/interprocess/sync/scoped_lock.hpp>
#include <boost/intrusive/pointer_traits.hpp>
#include <algorithm>
#include <utility>
#include <cstring>
#include <boost/assert.hpp>
#include <new>
/*!\file
Describes sequential fit algorithm used to allocate objects in shared memory.
This class is intended as a base class for single segment and multi-segment
implementations.
*/
namespace boost {
namespace interprocess {
namespace ipcdetail {
/*!This class implements the simple sequential fit algorithm with a simply
linked list of free buffers.
This class is intended as a base class for single segment and multi-segment
implementations.*/
template<class MutexFamily, class VoidPointer>
class simple_seq_fit_impl
{
//Non-copyable
simple_seq_fit_impl();
simple_seq_fit_impl(const simple_seq_fit_impl &);
simple_seq_fit_impl &operator=(const simple_seq_fit_impl &);
public:
/*!Shared interprocess_mutex family used for the rest of the Interprocess framework*/
typedef MutexFamily mutex_family;
/*!Pointer type to be used with the rest of the Interprocess framework*/
typedef VoidPointer void_pointer;
typedef typename boost::intrusive::pointer_traits<char_ptr>::difference_type difference_type;
typedef typename boost::make_unsigned<difference_type>::type size_type;
private:
struct block_ctrl;
typedef typename boost::intrusive::
pointer_traits<void_pointer>::template
rebind_pointer<block_ctrl>::type block_ctrl_ptr;
/*!Block control structure*/
struct block_ctrl
{
/*!Offset pointer to the next block.*/
block_ctrl_ptr m_next;
/*!This block's memory size (including block_ctrl
header) in BasicSize units*/
size_type m_size;
size_type get_user_bytes() const
{ return this->m_size*Alignment - BlockCtrlBytes; }
size_type get_total_bytes() const
{ return this->m_size*Alignment; }
static block_ctrl *get_block_from_addr(void *addr)
{
return reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(addr) - BlockCtrlBytes);
}
void *get_addr() const
{
return reinterpret_cast<block_ctrl*>
(reinterpret_cast<const char*>(this) + BlockCtrlBytes);
}
};
/*!Shared interprocess_mutex to protect memory allocate/deallocate*/
typedef typename MutexFamily::mutex_type interprocess_mutex;
/*!This struct includes needed data and derives from
interprocess_mutex to allow EBO when using null interprocess_mutex*/
struct header_t : public interprocess_mutex
{
/*!Pointer to the first free block*/
block_ctrl m_root;
/*!Allocated bytes for internal checking*/
size_type m_allocated;
/*!The size of the memory segment*/
size_type m_size;
} m_header;
public:
/*!Constructor. "size" is the total size of the managed memory segment,
"extra_hdr_bytes" indicates the extra bytes beginning in the sizeof(simple_seq_fit_impl)
offset that the allocator should not use at all.*/
simple_seq_fit_impl (size_type size, size_type extra_hdr_bytes);
/*!Destructor.*/
~simple_seq_fit_impl();
/*!Obtains the minimum size needed by the algorithm*/
static size_type get_min_size (size_type extra_hdr_bytes);
//Functions for single segment management
/*!Allocates bytes, returns 0 if there is not more memory*/
void* allocate (size_type nbytes);
/*!Deallocates previously allocated bytes*/
void deallocate (void *addr);
/*!Returns the size of the memory segment*/
size_type get_size() const;
/*!Increases managed memory in extra_size bytes more*/
void grow(size_type extra_size);
/*!Returns true if all allocated memory has been deallocated*/
bool all_memory_deallocated();
/*!Makes an internal sanity check and returns true if success*/
bool check_sanity();
//!Initializes to zero all the memory that's not in use.
//!This function is normally used for security reasons.
void clear_free_memory();
std::pair<void *, bool>
allocation_command (boost::interprocess::allocation_type command, size_type limit_size,
size_type preferred_size,size_type &received_size,
void *reuse_ptr = 0, size_type backwards_multiple = 1);
/*!Returns the size of the buffer previously allocated pointed by ptr*/
size_type size(void *ptr) const;
/*!Allocates aligned bytes, returns 0 if there is not more memory.
Alignment must be power of 2*/
void* allocate_aligned (size_type nbytes, size_type alignment);
/*!Allocates bytes, if there is no more memory, it executes functor
f(size_type) to allocate a new segment to manage. The functor returns
std::pair<void*, size_type> indicating the base address and size of
the new segment. If the new segment can't be allocated, allocate
it will return 0.*/
void* multi_allocate(size_type nbytes);
private:
/*!Real allocation algorithm with min allocation option*/
std::pair<void *, bool> priv_allocate(boost::interprocess::allocation_type command
,size_type min_size
,size_type preferred_size
,size_type &received_size
,void *reuse_ptr = 0);
/*!Returns next block if it's free.
Returns 0 if next block is not free.*/
block_ctrl *priv_next_block_if_free(block_ctrl *ptr);
/*!Returns previous block's if it's free.
Returns 0 if previous block is not free.*/
std::pair<block_ctrl*, block_ctrl*>priv_prev_block_if_free(block_ctrl *ptr);
/*!Real expand function implementation*/
bool priv_expand(void *ptr
,size_type min_size, size_type preferred_size
,size_type &received_size);
/*!Real expand to both sides implementation*/
void* priv_expand_both_sides(boost::interprocess::allocation_type command
,size_type min_size
,size_type preferred_size
,size_type &received_size
,void *reuse_ptr
,bool only_preferred_backwards);
/*!Real shrink function implementation*/
bool priv_shrink(void *ptr
,size_type max_size, size_type preferred_size
,size_type &received_size);
//!Real private aligned allocation function
void* priv_allocate_aligned (size_type nbytes, size_type alignment);
/*!Checks if block has enough memory and splits/unlinks the block
returning the address to the users*/
void* priv_check_and_allocate(size_type units
,block_ctrl* prev
,block_ctrl* block
,size_type &received_size);
/*!Real deallocation algorithm*/
void priv_deallocate(void *addr);
/*!Makes a new memory portion available for allocation*/
void priv_add_segment(void *addr, size_type size);
static const std::size_t Alignment = ::boost::alignment_of<boost::ipcdetail::max_align>::value;
static const std::size_t BlockCtrlBytes = ipcdetail::ct_rounded_size<sizeof(block_ctrl), Alignment>::value;
static const std::size_t BlockCtrlSize = BlockCtrlBytes/Alignment;
static const std::size_t MinBlockSize = BlockCtrlSize + Alignment;
public:
static const std::size_t PayloadPerAllocation = BlockCtrlBytes;
};
template<class MutexFamily, class VoidPointer>
inline simple_seq_fit_impl<MutexFamily, VoidPointer>::
simple_seq_fit_impl(size_type size, size_type extra_hdr_bytes)
{
//Initialize sizes and counters
m_header.m_allocated = 0;
m_header.m_size = size;
//Initialize pointers
size_type block1_off = ipcdetail::get_rounded_size(sizeof(*this)+extra_hdr_bytes, Alignment);
m_header.m_root.m_next = reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(this) + block1_off);
m_header.m_root.m_next->m_size = (size - block1_off)/Alignment;
m_header.m_root.m_next->m_next = &m_header.m_root;
}
template<class MutexFamily, class VoidPointer>
inline simple_seq_fit_impl<MutexFamily, VoidPointer>::~simple_seq_fit_impl()
{
//There is a memory leak!
// BOOST_ASSERT(m_header.m_allocated == 0);
// BOOST_ASSERT(m_header.m_root.m_next->m_next == block_ctrl_ptr(&m_header.m_root));
}
template<class MutexFamily, class VoidPointer>
inline void simple_seq_fit_impl<MutexFamily, VoidPointer>::grow(size_type extra_size)
{
//Old highest address block's end offset
size_type old_end = m_header.m_size/Alignment*Alignment;
//Update managed buffer's size
m_header.m_size += extra_size;
//We need at least MinBlockSize blocks to create a new block
if((m_header.m_size - old_end) < MinBlockSize){
return;
}
//We'll create a new free block with extra_size bytes
block_ctrl *new_block = reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(this) + old_end);
new_block->m_next = 0;
new_block->m_size = (m_header.m_size - old_end)/Alignment;
m_header.m_allocated += new_block->m_size*Alignment;
this->priv_deallocate(reinterpret_cast<char*>(new_block) + BlockCtrlBytes);
}
template<class MutexFamily, class VoidPointer>
inline void simple_seq_fit_impl<MutexFamily, VoidPointer>::priv_add_segment(void *addr, size_type size)
{
//Check size
BOOST_ASSERT(!(size < MinBlockSize));
if(size < MinBlockSize)
return;
//Construct big block using the new segment
block_ctrl *new_block = static_cast<block_ctrl *>(addr);
new_block->m_size = size/Alignment;
new_block->m_next = 0;
//Simulate this block was previously allocated
m_header.m_allocated += new_block->m_size*Alignment;
//Return block and insert it in the free block list
this->priv_deallocate(reinterpret_cast<char*>(new_block) + BlockCtrlBytes);
}
template<class MutexFamily, class VoidPointer>
inline typename simple_seq_fit_impl<MutexFamily, VoidPointer>::size_type
simple_seq_fit_impl<MutexFamily, VoidPointer>::get_size() const
{ return m_header.m_size; }
template<class MutexFamily, class VoidPointer>
inline typename simple_seq_fit_impl<MutexFamily, VoidPointer>::size_type
simple_seq_fit_impl<MutexFamily, VoidPointer>::
get_min_size (size_type extra_hdr_bytes)
{
return ipcdetail::get_rounded_size(sizeof(simple_seq_fit_impl)+extra_hdr_bytes
,Alignment)
+ MinBlockSize;
}
template<class MutexFamily, class VoidPointer>
inline bool simple_seq_fit_impl<MutexFamily, VoidPointer>::
all_memory_deallocated()
{
//-----------------------
boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
//-----------------------
return m_header.m_allocated == 0 &&
ipcdetail::to_raw_pointer(m_header.m_root.m_next->m_next) == &m_header.m_root;
}
template<class MutexFamily, class VoidPointer>
inline void simple_seq_fit_impl<MutexFamily, VoidPointer>::clear_free_memory()
{
//-----------------------
boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
//-----------------------
block_ctrl *block = ipcdetail::to_raw_pointer(m_header.m_root.m_next);
//Iterate through all free portions
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 = ipcdetail::to_raw_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 = ipcdetail::to_raw_pointer(m_header.m_root.m_next);
size_type free_memory = 0;
//Iterate through all blocks obtaining their size
do{
//Free blocks's next must be always valid
block_ctrl *next = ipcdetail::to_raw_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(size_type nbytes)
{
//-----------------------
boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
//-----------------------
size_type ignore;
return priv_allocate(boost::interprocess::allocate_new, nbytes, nbytes, ignore).first;
}
template<class MutexFamily, class VoidPointer>
inline void* simple_seq_fit_impl<MutexFamily, VoidPointer>::
allocate_aligned(size_type nbytes, size_type 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 (boost::interprocess::allocation_type command, size_type min_size,
size_type preferred_size,size_type &received_size,
void *reuse_ptr, size_type backwards_multiple)
{
//-----------------------
boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
//-----------------------
(void)backwards_multiple;
command &= ~boost::interprocess::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 typename simple_seq_fit_impl<MutexFamily, VoidPointer>::size_type
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(size_type nbytes)
{
//-----------------------
boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
//-----------------------
//Multisegment pointer. Let's try first the normal allocation
//since it's faster.
size_type ignore;
void *addr = this->priv_allocate(boost::interprocess::allocate_new, nbytes, nbytes, ignore).first;
if(!addr){
//If this fails we will try the allocation through the segment
//creator.
size_type 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));
BOOST_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(boost::interprocess::allocate_new, nbytes, nbytes, ignore).first;
}
}
return addr;
}
template<class MutexFamily, class VoidPointer>
void* simple_seq_fit_impl<MutexFamily, VoidPointer>::
priv_expand_both_sides(boost::interprocess::allocation_type command
,size_type min_size
,size_type preferred_size
,size_type &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 & boost::interprocess::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 & boost::interprocess::expand_bwd){
size_type 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;
}
size_type needs_backwards =
ipcdetail::get_rounded_size(preferred_size - extra_forward, Alignment);
if(!only_preferred_backwards){
needs_backwards =
max_value(ipcdetail::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)){
BOOST_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(boost::interprocess::allocation_type command
,size_type limit_size
,size_type preferred_size
,size_type &received_size
,void *reuse_ptr)
{
if(command & boost::interprocess::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)
size_type nunits = ipcdetail::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 = ipcdetail::to_raw_pointer(prev->m_next);
block_ctrl *root = &m_header.m_root;
block_ctrl *biggest_block = 0;
block_ctrl *prev_biggest_block = 0;
size_type biggest_size = limit_size;
//Expand in place
//reuse_ptr, limit_size, preferred_size, received_size
//
if(reuse_ptr && (command & (boost::interprocess::expand_fwd | boost::interprocess::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 & boost::interprocess::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 = ipcdetail::to_raw_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 = ipcdetail::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 & (boost::interprocess::expand_fwd | boost::interprocess::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
size_type 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 = ipcdetail::to_raw_pointer(root->m_next);
while((reinterpret_cast<char*>(prev_block) + prev_block->m_size*Alignment)
!= (reinterpret_cast<char*>(ptr))
&& prev_block != root){
prev_2_block = prev_block;
prev_block = ipcdetail::to_raw_pointer(prev_block->m_next);
}
if(prev_block == root || !prev_block->m_next)
return prev_pair_t(0, 0);
//Check if the previous block is in the managed segment
size_type distance = (reinterpret_cast<char*>(prev_block) - reinterpret_cast<char*>(this))/Alignment;
if(distance >= (m_header.m_size/Alignment)){
//"previous_block" does not exist so we can't expand "block"
return prev_pair_t(0, 0);
}
return prev_pair_t(prev_2_block, prev_block);
}
template<class MutexFamily, class VoidPointer>
inline bool simple_seq_fit_impl<MutexFamily, VoidPointer>::
priv_expand (void *ptr
,size_type min_size
,size_type preferred_size
,size_type &received_size)
{
//Obtain the real size of the block
block_ctrl *block = reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(ptr) - BlockCtrlBytes);
size_type old_block_size = block->m_size;
//All used blocks' next is marked with 0 so check it
BOOST_ASSERT(block->m_next == 0);
//Put this to a safe value
received_size = old_block_size*Alignment - BlockCtrlBytes;
//Now translate it to Alignment units
min_size = ipcdetail::get_rounded_size(min_size, Alignment)/Alignment;
preferred_size = ipcdetail::get_rounded_size(preferred_size, Alignment)/Alignment;
//Some parameter checks
if(min_size > preferred_size)
return false;
size_type data_size = old_block_size - BlockCtrlSize;
if(data_size >= min_size)
return true;
block_ctrl *next_block = priv_next_block_if_free(block);
if(!next_block){
return false;
}
//Is "block" + "next_block" big enough?
size_type merged_size = old_block_size + next_block->m_size;
//Now we can expand this block further than before
received_size = merged_size*Alignment - BlockCtrlBytes;
if(merged_size < (min_size + BlockCtrlSize)){
return false;
}
//We can fill expand. Merge both blocks,
block->m_next = next_block->m_next;
block->m_size = merged_size;
//Find the previous free block of next_block
block_ctrl *prev = &m_header.m_root;
while(ipcdetail::to_raw_pointer(prev->m_next) != next_block){
prev = ipcdetail::to_raw_pointer(prev->m_next);
}
//Now insert merged block in the free list
//This allows reusing allocation logic in this function
m_header.m_allocated -= old_block_size*Alignment;
prev->m_next = block;
//Now use check and allocate to do the allocation logic
preferred_size += BlockCtrlSize;
size_type nunits = preferred_size < merged_size ? preferred_size : merged_size;
//This must success since nunits is less than merged_size!
if(!this->priv_check_and_allocate (nunits, prev, block, received_size)){
//Something very ugly is happening here. This is a bug
//or there is memory corruption
BOOST_ASSERT(0);
return false;
}
return true;
}
template<class MutexFamily, class VoidPointer>
inline bool simple_seq_fit_impl<MutexFamily, VoidPointer>::
priv_shrink (void *ptr
,size_type max_size
,size_type preferred_size
,size_type &received_size)
{
//Obtain the real size of the block
block_ctrl *block = reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(ptr) - BlockCtrlBytes);
size_type block_size = block->m_size;
//All used blocks' next is marked with 0 so check it
BOOST_ASSERT(block->m_next == 0);
//Put this to a safe value
received_size = block_size*Alignment - BlockCtrlBytes;
//Now translate it to Alignment units
max_size = max_size/Alignment;
preferred_size = ipcdetail::get_rounded_size(preferred_size, Alignment)/Alignment;
//Some parameter checks
if(max_size < preferred_size)
return false;
size_type data_size = block_size - BlockCtrlSize;
if(data_size < preferred_size)
return false;
if(data_size == preferred_size)
return true;
//We must be able to create at least a new empty block
if((data_size - preferred_size) < BlockCtrlSize){
return false;
}
//Now we can just rewrite the size of the old buffer
block->m_size = preferred_size + BlockCtrlSize;
//Update new size
received_size = preferred_size*Alignment;
//We create the new block
block = reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(block) + block->m_size*Alignment);
//Write control data to simulate this new block was previously allocated
block->m_next = 0;
block->m_size = data_size - preferred_size;
//Now deallocate the new block to insert it in the free list
this->priv_deallocate(reinterpret_cast<char*>(block)+BlockCtrlBytes);
return true;
}
template<class MutexFamily, class VoidPointer>
inline void* simple_seq_fit_impl<MutexFamily, VoidPointer>::
priv_allocate_aligned(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 ignore;
if(alignment <= Alignment){
return priv_allocate(boost::interprocess::allocate_new, nbytes, nbytes, ignore).first;
}
size_type request =
nbytes + alignment + MinBlockSize*Alignment - BlockCtrlBytes;
void *buffer = priv_allocate(boost::interprocess::allocate_new, request, request, ignore).first;
if(!buffer)
return 0;
else if ((((std::size_t)(buffer)) % alignment) == 0)
return buffer;
char *aligned_portion = reinterpret_cast<char*>
(reinterpret_cast<size_type>(static_cast<char*>(buffer) + alignment - 1) & -alignment);
char *pos = ((aligned_portion - reinterpret_cast<char*>(buffer)) >= (MinBlockSize*Alignment)) ?
aligned_portion : (aligned_portion + alignment);
block_ctrl *first = reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(buffer) - BlockCtrlBytes);
block_ctrl *second = reinterpret_cast<block_ctrl*>(pos - BlockCtrlBytes);
size_type old_size = first->m_size;
first->m_size = (reinterpret_cast<char*>(second) - reinterpret_cast<char*>(first))/Alignment;
second->m_size = old_size - first->m_size;
//Write control data to simulate this new block was previously allocated
second->m_next = 0;
//Now deallocate the new block to insert it in the free list
this->priv_deallocate(reinterpret_cast<char*>(first) + BlockCtrlBytes);
return reinterpret_cast<char*>(second) + BlockCtrlBytes;
}
template<class MutexFamily, class VoidPointer> inline
void* simple_seq_fit_impl<MutexFamily, VoidPointer>::priv_check_and_allocate
(size_type nunits
,typename simple_seq_fit_impl<MutexFamily, VoidPointer>::block_ctrl* prev
,typename simple_seq_fit_impl<MutexFamily, VoidPointer>::block_ctrl* block
,size_type &received_size)
{
size_type upper_nunits = nunits + BlockCtrlSize;
bool found = false;
if (block->m_size > upper_nunits){
//This block is bigger than needed, split it in
//two blocks, the first's size will be (block->m_size-units)
//the second's size (units)
size_type total_size = block->m_size;
block->m_size = nunits;
block_ctrl *new_block = reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(block) + Alignment*nunits);
new_block->m_size = total_size - nunits;
new_block->m_next = block->m_next;
prev->m_next = new_block;
found = true;
}
else if (block->m_size >= nunits){
//This block has exactly the right size with an extra
//unusable extra bytes.
prev->m_next = block->m_next;
found = true;
}
if(found){
//We need block_ctrl for deallocation stuff, so
//return memory user can overwrite
m_header.m_allocated += block->m_size*Alignment;
received_size = block->m_size*Alignment - BlockCtrlBytes;
//Mark the block as allocated
block->m_next = 0;
//Check alignment
BOOST_ASSERT(((reinterpret_cast<char*>(block) - reinterpret_cast<char*>(this))
% Alignment) == 0 );
return reinterpret_cast<char*>(block) + BlockCtrlBytes;
}
return 0;
}
template<class MutexFamily, class VoidPointer>
void simple_seq_fit_impl<MutexFamily, VoidPointer>::deallocate(void* addr)
{
if(!addr) return;
//-----------------------
boost::interprocess::scoped_lock<interprocess_mutex> guard(m_header);
//-----------------------
return this->priv_deallocate(addr);
}
template<class MutexFamily, class VoidPointer>
void simple_seq_fit_impl<MutexFamily, VoidPointer>::priv_deallocate(void* addr)
{
if(!addr) return;
//Let's get free block list. List is always sorted
//by memory address to allow block merging.
//Pointer next always points to the first
//(lower address) block
block_ctrl_ptr prev = &m_header.m_root;
block_ctrl_ptr pos = m_header.m_root.m_next;
block_ctrl_ptr block = reinterpret_cast<block_ctrl*>
(reinterpret_cast<char*>(addr) - BlockCtrlBytes);
//All used blocks' next is marked with 0 so check it
BOOST_ASSERT(block->m_next == 0);
//Check if alignment and block size are right
BOOST_ASSERT((reinterpret_cast<char*>(addr) - reinterpret_cast<char*>(this))
% Alignment == 0 );
size_type total_size = Alignment*block->m_size;
BOOST_ASSERT(m_header.m_allocated >= total_size);
//Update used memory count
m_header.m_allocated -= total_size;
//Let's find the previous and the next block of the block to deallocate
//This ordering comparison must be done with original pointers
//types since their mapping to raw pointers can be different
//in each process
while((ipcdetail::to_raw_pointer(pos) != &m_header.m_root) && (block > pos)){
prev = pos;
pos = pos->m_next;
}
//Try to combine with upper block
if ((reinterpret_cast<char*>(ipcdetail::to_raw_pointer(block))
+ Alignment*block->m_size) ==
reinterpret_cast<char*>(ipcdetail::to_raw_pointer(pos))){
block->m_size += pos->m_size;
block->m_next = pos->m_next;
}
else{
block->m_next = pos;
}
//Try to combine with lower block
if ((reinterpret_cast<char*>(ipcdetail::to_raw_pointer(prev))
+ Alignment*prev->m_size) ==
reinterpret_cast<char*>(ipcdetail::to_raw_pointer(block))){
prev->m_size += block->m_size;
prev->m_next = block->m_next;
}
else{
prev->m_next = block;
}
}
} //namespace ipcdetail {
} //namespace interprocess {
} //namespace boost {
#include <boost/interprocess/detail/config_end.hpp>
#endif //#ifndef BOOST_INTERPROCESS_MEM_ALGO_DETAIL_SIMPLE_SEQ_FIT_IMPL_HPP