...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::container::adaptive_pool
// In header: <boost/container/adaptive_pool.hpp> template<typename T, std::size_t NodesPerBlock = ADP_nodes_per_block, std::size_t MaxFreeBlocks = ADP_max_free_blocks, std::size_t OverheadPercent = ADP_overhead_percent> class adaptive_pool { public: // types typedef unsigned int allocation_type; typedef adaptive_pool< T, NodesPerBlock, MaxFreeBlocks, OverheadPercent > self_t; typedef T value_type; typedef T * pointer; typedef const T * const_pointer; typedef unspecified reference; typedef unspecified const_reference; typedef std::size_t size_type; typedef std::ptrdiff_t difference_type; typedef unspecified version; // member classes/structs/unions template<typename T2> struct rebind { // types typedef adaptive_pool< T2, NodesPerBlock, MaxFreeBlocks, OverheadPercent > other; }; // construct/copy/destruct adaptive_pool() noexcept; adaptive_pool(const adaptive_pool &) noexcept; template<typename T2> adaptive_pool(const adaptive_pool< T2, NodesPerBlock, MaxFreeBlocks, OverheadPercent BOOST_CONTAINER_DOCIGN(BOOST_MOVE_I Version)> &) noexcept; ~adaptive_pool(); // public member functions BOOST_CONTAINER_DOCIGN(BOOST_STATIC_ASSERT((Version<=2))); size_type max_size() const noexcept; pointer allocate(size_type, const void * = 0); void deallocate(const pointer &, size_type) noexcept; pointer allocation_command(allocation_type, size_type, size_type &, pointer &); size_type size(pointer) const noexcept; pointer allocate_one(); void allocate_individual(std::size_t, multiallocation_chain &); void deallocate_one(pointer) noexcept; void deallocate_individual(multiallocation_chain &) noexcept; void allocate_many(size_type, std::size_t, multiallocation_chain &); void allocate_many(const size_type *, size_type, multiallocation_chain &); void deallocate_many(multiallocation_chain &) noexcept; // public static functions static void deallocate_free_blocks() noexcept; // friend functions friend void swap(adaptive_pool &, adaptive_pool &) noexcept; friend bool operator==(const adaptive_pool &, const adaptive_pool &) noexcept; friend bool operator!=(const adaptive_pool &, const adaptive_pool &) noexcept; // private member functions pointer priv_allocation_command(allocation_type, std::size_t, size_type &, pointer &); // public data members static const std::size_t nodes_per_block; static const std::size_t max_free_blocks; static const std::size_t overhead_percent; static const std::size_t real_nodes_per_block; };
An STL node allocator that uses a modified DLMalloc as memory source.
This node allocator shares a segregated storage between all instances of adaptive_pool with equal sizeof(T).
NodesPerBlock is the number of nodes allocated at once when the allocator needs runs out of nodes. MaxFreeBlocks is the maximum number of totally free blocks that the adaptive node pool will hold. The rest of the totally free blocks will be deallocated to the memory manager.
OverheadPercent is the (approximated) maximum size overhead (1-20%) of the allocator: (memory usable for nodes / total memory allocated from the memory allocator)
adaptive_pool
public
construct/copy/destructadaptive_pool() noexcept;Default constructor.
adaptive_pool(const adaptive_pool &) noexcept;Copy constructor from other
adaptive_pool
. template<typename T2> adaptive_pool(const adaptive_pool< T2, NodesPerBlock, MaxFreeBlocks, OverheadPercent BOOST_CONTAINER_DOCIGN(BOOST_MOVE_I Version)> &) noexcept;Copy constructor from related
adaptive_pool
. ~adaptive_pool();Destructor.
adaptive_pool
public member functionsBOOST_CONTAINER_DOCIGN(BOOST_STATIC_ASSERT((Version<=2)));
size_type max_size() const noexcept;
Returns the number of elements that could be allocated. Never throws
pointer allocate(size_type count, const void * = 0);
Allocate memory for an array of count elements. Throws std::bad_alloc if there is no enough memory
void deallocate(const pointer & ptr, size_type count) noexcept;
Deallocate allocated memory. Never throws
pointer allocation_command(allocation_type command, size_type limit_size, size_type & prefer_in_recvd_out_size, pointer & reuse);
size_type size(pointer p) const noexcept;
Returns maximum the number of objects the previously allocated memory pointed by p can hold.
pointer allocate_one();
Allocates just one object. Memory allocated with this function must be deallocated only with deallocate_one(). Throws bad_alloc if there is no enough memory
void allocate_individual(std::size_t num_elements, multiallocation_chain & chain);
Allocates many elements of size == 1. Elements must be individually deallocated with deallocate_one()
void deallocate_one(pointer p) noexcept;
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_individual(multiallocation_chain & chain) noexcept;
void allocate_many(size_type elem_size, std::size_t n_elements, multiallocation_chain & chain);
Allocates many elements of size elem_size. Elements must be individually deallocated with deallocate()
void allocate_many(const size_type * elem_sizes, size_type n_elements, multiallocation_chain & chain);
Allocates n_elements elements, each one of size elem_sizes[i] Elements must be individually deallocated with deallocate()
void deallocate_many(multiallocation_chain & chain) noexcept;
adaptive_pool
friend functionsfriend void swap(adaptive_pool &, adaptive_pool &) noexcept;
Swaps allocators. Does not throw. If each allocator is placed in a different memory segment, the result is undefined.
friend bool operator==(const adaptive_pool &, const adaptive_pool &) noexcept;
An allocator always compares to true, as memory allocated with one instance can be deallocated by another instance
friend bool operator!=(const adaptive_pool &, const adaptive_pool &) noexcept;
An allocator always compares to false, as memory allocated with one instance can be deallocated by another instance