boost/interprocess/allocators/detail/allocator_common.hpp
////////////////////////////////////////////////////////////////////////////// // // (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_ALLOCATOR_DETAIL_ALLOCATOR_COMMON_HPP #define BOOST_INTERPROCESS_ALLOCATOR_DETAIL_ALLOCATOR_COMMON_HPP #include <boost/interprocess/detail/config_begin.hpp> #include <boost/interprocess/detail/workaround.hpp> #include <boost/pointer_to_other.hpp> #include <boost/interprocess/interprocess_fwd.hpp> #include <boost/interprocess/detail/utilities.hpp> //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/containers/allocation_type.hpp> //boost::interprocess::allocation_type #include <boost/interprocess/mem_algo/detail/mem_algo_common.hpp> #include <boost/interprocess/detail/segment_manager_helper.hpp> #include <algorithm> //std::swap #include <boost/interprocess/detail/move.hpp> #include <boost/interprocess/detail/type_traits.hpp> #include <boost/interprocess/detail/utilities.hpp> namespace boost { namespace interprocess { template <class T> struct sizeof_value { static const std::size_t value = sizeof(T); }; template <> struct sizeof_value<void> { static const std::size_t value = sizeof(void*); }; template <> struct sizeof_value<const void> { static const std::size_t value = sizeof(void*); }; template <> struct sizeof_value<volatile void> { static const std::size_t value = sizeof(void*); }; template <> struct sizeof_value<const volatile void> { static const std::size_t value = sizeof(void*); }; 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>(boost::interprocess::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>(boost::interprocess::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::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()){ m_cached_nodes = mp_node_pool->allocate_nodes(m_max_cached_nodes/2); } void *ret = detail::get_pointer(m_cached_nodes.front()); m_cached_nodes.pop_front(); return ret; } multiallocation_chain cached_allocation(std::size_t n) { multiallocation_chain chain; std::size_t count = n, allocated(0); 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 = detail::get_pointer(m_cached_nodes.front()); m_cached_nodes.pop_front(); chain.push_back(ret); ++allocated; } if(allocated != n){ multiallocation_chain chain2(mp_node_pool->allocate_nodes(n - allocated)); chain.splice_after(chain.last(), chain2, chain2.before_begin(), chain2.last(), n - allocated); } return boost::interprocess::move(chain); } BOOST_CATCH(...){ this->cached_deallocation(boost::interprocess::move(chain)); 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_chain chain) { m_cached_nodes.splice_after(m_cached_nodes.before_begin(), chain); //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(boost::interprocess::move(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 boost:: pointer_to_other<void_pointer, T>::type pointer; typedef typename boost:: 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 detail::transform_multiallocation_chain <typename SegmentManager::multiallocation_chain, T>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(boost::interprocess::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_chain allocate_many(size_type elem_size, std::size_t num_elements) { return 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_chain allocate_many(const size_type *elem_sizes, size_type n_elements) { return 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_chain chain) { return this->derived()->get_segment_manager()->deallocate_many(boost::interprocess::move(chain)); } //!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 boost:: pointer_to_other<void_pointer, const void>::type cvoid_pointer; public: typedef typename boost:: pointer_to_other<void_pointer, T>::type pointer; typedef typename boost:: 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 detail::transform_multiallocation_chain <typename SegmentManager::multiallocation_chain, T>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()); if(count > this->max_size()) throw bad_alloc(); else if(Version == 1 && count == 1) return pointer(static_cast<value_type*> (pool->allocate_node())); else return pointer(static_cast<value_type*> (pool->get_segment_manager()->allocate(sizeof(T)*count))); } //!Deallocate allocated memory. Never throws void deallocate(const pointer &ptr, size_type count) { (void)count; typedef typename node_pool<0>::type node_pool_t; node_pool_t *pool = node_pool<0>::get(this->derived()->get_node_pool()); if(Version == 1 && count == 1) pool->deallocate_node(detail::get_pointer(ptr)); else pool->get_segment_manager()->deallocate((void*)detail::get_pointer(ptr)); } //!Allocates just one object. Memory allocated with this function //!must be deallocated only with deallocate_one(). //!Throws boost::interprocess::bad_alloc if there is no enough memory pointer allocate_one() { typedef typename node_pool<0>::type node_pool_t; node_pool_t *pool = node_pool<0>::get(this->derived()->get_node_pool()); return pointer(static_cast<value_type*>(pool->allocate_node())); } //!Allocates many elements of size == 1 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. Memory allocated with this function //!must be deallocated only with deallocate_one(). multiallocation_chain allocate_individual(std::size_t num_elements) { typedef typename node_pool<0>::type node_pool_t; node_pool_t *pool = node_pool<0>::get(this->derived()->get_node_pool()); return multiallocation_chain(pool->allocate_nodes(num_elements)); } //!Deallocates memory previously allocated with allocate_one(). //!You should never use deallocate_one to deallocate memory allocated //!with other functions different from allocate_one(). Never throws void deallocate_one(const pointer &p) { typedef typename node_pool<0>::type node_pool_t; node_pool_t *pool = node_pool<0>::get(this->derived()->get_node_pool()); pool->deallocate_node(detail::get_pointer(p)); } //!Allocates many elements of size == 1 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. Memory allocated with this function //!must be deallocated only with deallocate_one(). void deallocate_individual(multiallocation_chain chain) { node_pool<0>::get(this->derived()->get_node_pool())->deallocate_nodes (chain.extract_multiallocation_chain()); } //!Deallocates all free blocks of the pool void deallocate_free_blocks() { node_pool<0>::get(this->derived()->get_node_pool())->deallocate_free_blocks(); } //!Deprecated, use deallocate_free_blocks. //!Deallocates all free chunks of the pool. void deallocate_free_chunks() { node_pool<0>::get(this->derived()->get_node_pool())->deallocate_free_blocks(); } }; template<class T, class NodePool, unsigned int Version> class cached_allocator_impl : public array_allocation_impl <cached_allocator_impl<T, NodePool, Version>, T, typename NodePool::segment_manager> { cached_allocator_impl & operator=(const cached_allocator_impl& other); typedef array_allocation_impl < cached_allocator_impl <T, NodePool, Version> , T , typename NodePool::segment_manager> base_t; public: typedef NodePool node_pool_t; typedef typename NodePool::segment_manager segment_manager; typedef typename segment_manager::void_pointer void_pointer; typedef typename boost:: pointer_to_other<void_pointer, const void>::type cvoid_pointer; typedef typename base_t::pointer pointer; typedef typename base_t::size_type size_type; typedef typename base_t::multiallocation_chain multiallocation_chain; typedef typename base_t::value_type value_type; public: enum { DEFAULT_MAX_CACHED_NODES = 64 }; cached_allocator_impl(segment_manager *segment_mngr, std::size_t max_cached_nodes) : m_cache(segment_mngr, max_cached_nodes) {} cached_allocator_impl(const cached_allocator_impl &other) : m_cache(other.m_cache) {} //!Copy constructor from related cached_adaptive_pool_base. If not present, constructs //!a node pool. Increments the reference count of the associated node pool. //!Can throw boost::interprocess::bad_alloc template<class T2, class NodePool2> cached_allocator_impl (const cached_allocator_impl <T2, NodePool2, Version> &other) : m_cache(other.get_segment_manager(), other.get_max_cached_nodes()) {} //!Returns a pointer to the node pool. //!Never throws node_pool_t* get_node_pool() const { return m_cache.get_node_pool(); } //!Returns the segment manager. //!Never throws segment_manager* get_segment_manager()const { return m_cache.get_segment_manager(); } //!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_cache.set_max_cached_nodes(newmax); } //!Returns the max cached nodes parameter. //!Never throws std::size_t get_max_cached_nodes() const { return m_cache.get_max_cached_nodes(); } //!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; void * ret; if(count > this->max_size()) throw bad_alloc(); else if(Version == 1 && count == 1){ ret = m_cache.cached_allocation(); } else{ ret = this->get_segment_manager()->allocate(sizeof(T)*count); } return pointer(static_cast<T*>(ret)); } //!Deallocate allocated memory. Never throws void deallocate(const pointer &ptr, size_type count) { (void)count; if(Version == 1 && count == 1){ m_cache.cached_deallocation(detail::get_pointer(ptr)); } else{ this->get_segment_manager()->deallocate((void*)detail::get_pointer(ptr)); } } //!Allocates just one object. Memory allocated with this function //!must be deallocated only with deallocate_one(). //!Throws boost::interprocess::bad_alloc if there is no enough memory pointer allocate_one() { return pointer(static_cast<value_type*>(this->m_cache.cached_allocation())); } //!Allocates many elements of size == 1 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. Memory allocated with this function //!must be deallocated only with deallocate_one(). multiallocation_chain allocate_individual(std::size_t num_elements) { return multiallocation_chain(this->m_cache.cached_allocation(num_elements)); } //!Deallocates memory previously allocated with allocate_one(). //!You should never use deallocate_one to deallocate memory allocated //!with other functions different from allocate_one(). Never throws void deallocate_one(const pointer &p) { this->m_cache.cached_deallocation(detail::get_pointer(p)); } //!Allocates many elements of size == 1 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. Memory allocated with this function //!must be deallocated only with deallocate_one(). void deallocate_individual(multiallocation_chain chain) { typename node_pool_t::multiallocation_chain mem (chain.extract_multiallocation_chain()); m_cache.cached_deallocation(boost::interprocess::move(mem)); } //!Deallocates all free blocks of the pool void deallocate_free_blocks() { m_cache.get_node_pool()->deallocate_free_blocks(); } //!Swaps allocators. Does not throw. If each allocator is placed in a //!different shared memory segments, the result is undefined. friend void swap(cached_allocator_impl &alloc1, cached_allocator_impl &alloc2) { detail::do_swap(alloc1.mp_node_pool, alloc2.mp_node_pool); alloc1.m_cached_nodes.swap(alloc2.m_cached_nodes); detail::do_swap(alloc1.m_max_cached_nodes, alloc2.m_max_cached_nodes); } void deallocate_cache() { m_cache.deallocate_all_cached_nodes(); } //!Deprecated use deallocate_free_blocks. void deallocate_free_chunks() { m_cache.get_node_pool()->deallocate_free_blocks(); } /// @cond private: cache_impl<node_pool_t> m_cache; }; //!Equality test for same type of //!cached_allocator_impl template<class T, class N, unsigned int V> inline bool operator==(const cached_allocator_impl<T, N, V> &alloc1, const cached_allocator_impl<T, N, V> &alloc2) { return alloc1.get_node_pool() == alloc2.get_node_pool(); } //!Inequality test for same type of //!cached_allocator_impl template<class T, class N, unsigned int V> inline bool operator!=(const cached_allocator_impl<T, N, V> &alloc1, const cached_allocator_impl<T, N, V> &alloc2) { return alloc1.get_node_pool() != alloc2.get_node_pool(); } //!Pooled shared memory allocator using adaptive pool. Includes //!a reference count but the class does not delete itself, this is //!responsibility of user classes. Node size (NodeSize) and the number of //!nodes allocated per block (NodesPerBlock) are known at compile time template<class private_node_allocator_t> class shared_pool_impl : public private_node_allocator_t { public: //!Segment manager typedef typedef typename private_node_allocator_t:: segment_manager segment_manager; typedef typename private_node_allocator_t:: multiallocation_chain multiallocation_chain; private: typedef typename segment_manager::mutex_family::mutex_type mutex_type; public: //!Constructor from a segment manager. Never throws shared_pool_impl(segment_manager *segment_mngr) : private_node_allocator_t(segment_mngr) {} //!Destructor. Deallocates all allocated blocks. Never throws ~shared_pool_impl() {} //!Allocates array of count elements. Can throw boost::interprocess::bad_alloc void *allocate_node() { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- return private_node_allocator_t::allocate_node(); } //!Deallocates an array pointed by ptr. Never throws void deallocate_node(void *ptr) { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- private_node_allocator_t::deallocate_node(ptr); } /* //!Allocates a singly linked list of n nodes ending in null pointer. //!can throw boost::interprocess::bad_alloc void allocate_nodes(multiallocation_chain &nodes, std::size_t n) { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- return private_node_allocator_t::allocate_nodes(nodes, n); } */ //!Allocates n nodes. //!Can throw boost::interprocess::bad_alloc multiallocation_chain allocate_nodes(const std::size_t n) { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- return private_node_allocator_t::allocate_nodes(n); } //!Deallocates a linked list of nodes ending in null pointer. Never throws void deallocate_nodes(multiallocation_chain &nodes, std::size_t num) { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- private_node_allocator_t::deallocate_nodes(nodes, num); } //!Deallocates the nodes pointed by the multiallocation iterator. Never throws void deallocate_nodes(multiallocation_chain chain) { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- private_node_allocator_t::deallocate_nodes(boost::interprocess::move(chain)); } //!Deallocates all the free blocks of memory. Never throws void deallocate_free_blocks() { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- private_node_allocator_t::deallocate_free_blocks(); } //!Deallocates all used memory from the common pool. //!Precondition: all nodes allocated from this pool should //!already be deallocated. Otherwise, undefined behavior. Never throws void purge_blocks() { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- private_node_allocator_t::purge_blocks(); } //!Increments internal reference count and returns new count. Never throws std::size_t inc_ref_count() { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- return ++m_header.m_usecount; } //!Decrements internal reference count and returns new count. Never throws std::size_t dec_ref_count() { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- assert(m_header.m_usecount > 0); return --m_header.m_usecount; } //!Deprecated, use deallocate_free_blocks. void deallocate_free_chunks() { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- private_node_allocator_t::deallocate_free_blocks(); } //!Deprecated, use purge_blocks. void purge_chunks() { //----------------------- boost::interprocess::scoped_lock<mutex_type> guard(m_header); //----------------------- private_node_allocator_t::purge_blocks(); } private: //!This struct includes needed data and derives from //!interprocess_mutex to allow EBO when using null_mutex struct header_t : mutex_type { std::size_t m_usecount; //Number of attached allocators header_t() : m_usecount(0) {} } m_header; }; } //namespace detail { } //namespace interprocess { } //namespace boost { #include <boost/interprocess/detail/config_end.hpp> #endif //#ifndef BOOST_INTERPROCESS_ALLOCATOR_DETAIL_ALLOCATOR_COMMON_HPP