...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::interprocess::segment_manager
// In header: <boost/interprocess/segment_manager.hpp> template<typename CharType, typename MemoryAlgorithm, template< class IndexConfig > class IndexType> class segment_manager : public boost::interprocess::segment_manager_base< MemoryAlgorithm > { public: // types typedef MemoryAlgorithm memory_algorithm; typedef segment_manager_base_t::void_pointer void_pointer; typedef segment_manager_base_t::size_type size_type; typedef segment_manager_base_t::difference_type difference_type; typedef CharType char_type; typedef segment_manager_base< MemoryAlgorithm > segment_manager_base_type; typedef segment_manager_base_t::mutex_family mutex_family; typedef transform_iterator< typename named_index_t::const_iterator, named_transform > const_named_iterator; typedef transform_iterator< typename unique_index_t::const_iterator, unique_transform > const_unique_iterator; // member classes/structs/unions template<typename T> struct allocator { // types typedef boost::interprocess::allocator< T, segment_manager > type; }; template<typename T> struct deleter { // types typedef boost::interprocess::deleter< T, segment_manager > type; }; // construct/copy/destruct explicit segment_manager(size_type); // public member functions template<typename T> std::pair< T *, size_type > find(char_ptr_holder_t); template<typename T> std::pair< T *, size_type > find_no_lock(char_ptr_holder_t); template<typename T> construct_proxy< T >::type construct(char_ptr_holder_t); template<typename T> construct_proxy< T >::type find_or_construct(char_ptr_holder_t); template<typename T> construct_proxy< T >::type construct(char_ptr_holder_t, const std::nothrow_t &); template<typename T> construct_proxy< T >::type find_or_construct(char_ptr_holder_t, const std::nothrow_t &); template<typename T> construct_iter_proxy< T >::type construct_it(char_ptr_holder_t); template<typename T> construct_iter_proxy< T >::type find_or_construct_it(char_ptr_holder_t); template<typename T> construct_iter_proxy< T >::type construct_it(char_ptr_holder_t, const std::nothrow_t &); template<typename T> construct_iter_proxy< T >::type find_or_construct_it(char_ptr_holder_t, const std::nothrow_t &); template<typename Func> void atomic_func(Func &); template<typename Func> bool try_atomic_func(Func &); template<typename T> bool destroy(char_ptr_holder_t); template<typename T> void destroy_ptr(const T *); void reserve_named_objects(size_type); void reserve_unique_objects(size_type); void shrink_to_fit_indexes(); size_type get_num_named_objects(); size_type get_num_unique_objects(); const_named_iterator named_begin() const; const_named_iterator named_end() const; const_unique_iterator unique_begin() const; const_unique_iterator unique_end() const; template<typename T> allocator< T >::type get_allocator(); template<typename T> deleter< T >::type get_deleter(); // public static functions template<typename T> static const CharType * get_instance_name(const T *); template<typename T> static size_type get_instance_length(const T *); template<typename T> static instance_type get_instance_type(const T *); static size_type get_min_size(); // public data members static const size_type PayloadPerAllocation; };
This object is placed in the beginning of memory segment and implements the allocation (named or anonymous) of portions of the segment. This object contains two indexes that maintain an association between a name and a portion of the segment.
The first index contains the mappings for normal named objects using the char type specified in the template parameter.
The second index contains the association for unique instances. The key will be the const char * returned from type_info.name() function for the unique type to be constructed.
segment_manager<CharType, MemoryAlgorithm, IndexType> inherits publicly from segment_manager_base<MemoryAlgorithm> and inherits from it many public functions related to anonymous object and raw memory allocation. See segment_manager_base reference to know about those functions.
segment_manager
public member functionstemplate<typename T> std::pair< T *, size_type > find(char_ptr_holder_t name);
Tries to find a previous named/unique allocation. Returns the address and the object count. On failure the first member of the returned pair is 0.
template<typename T> std::pair< T *, size_type > find_no_lock(char_ptr_holder_t name);
Tries to find a previous named/unique allocation. Returns the address and the object count. On failure the first member of the returned pair is 0. This search is not mutex-protected! Use it only inside atomic_func() calls, where the internal mutex is guaranteed to be locked.
template<typename T> construct_proxy< T >::type construct(char_ptr_holder_t name);
Returns throwing "construct" proxy object
template<typename T> construct_proxy< T >::type find_or_construct(char_ptr_holder_t name);
Returns throwing "search or construct" proxy object
template<typename T> construct_proxy< T >::type construct(char_ptr_holder_t name, const std::nothrow_t &);
Returns no throwing "construct" proxy object
template<typename T> construct_proxy< T >::type find_or_construct(char_ptr_holder_t name, const std::nothrow_t &);
Returns no throwing "search or construct" proxy object
template<typename T> construct_iter_proxy< T >::type construct_it(char_ptr_holder_t name);Returns throwing "construct from iterators" proxy object.
template<typename T> construct_iter_proxy< T >::type find_or_construct_it(char_ptr_holder_t name);
Returns throwing "search or construct from iterators" proxy object
template<typename T> construct_iter_proxy< T >::type construct_it(char_ptr_holder_t name, const std::nothrow_t &);
Returns no throwing "construct from iterators" proxy object
template<typename T> construct_iter_proxy< T >::type find_or_construct_it(char_ptr_holder_t name, const std::nothrow_t &);
Returns no throwing "search or construct from iterators" proxy object
template<typename Func> void atomic_func(Func & f);
Calls object function blocking recursive interprocess_mutex
and guarantees that no new named_alloc or destroy will be executed by any process while executing the object function call
template<typename Func> bool try_atomic_func(Func & f);
Tries to calls a functor guaranteeing that no new construction, search or destruction will be executed by any process while executing the object function call. If the atomic function can't be immediatelly executed because the internal mutex is already locked, returns false. If the functor throws, this function throws.
template<typename T> bool destroy(char_ptr_holder_t name);
Destroys a previously created named/unique instance. Returns false if the object was not present.
template<typename T> void destroy_ptr(const T * p);
Destroys an anonymous, unique or named object using its address
void reserve_named_objects(size_type num);
Preallocates needed index resources to optimize the creation of "num" named objects in the managed memory segment. Can throw boost::interprocess::bad_alloc
if there is no enough memory.
void reserve_unique_objects(size_type num);
Preallocates needed index resources to optimize the creation of "num" unique objects in the managed memory segment. Can throw boost::interprocess::bad_alloc
if there is no enough memory.
void shrink_to_fit_indexes();
Calls shrink_to_fit in both named and unique object indexes to try to free unused memory from those indexes.
size_type get_num_named_objects();
Returns the number of named objects stored in the segment.
size_type get_num_unique_objects();
Returns the number of unique objects stored in the segment.
const_named_iterator named_begin() const;
Returns a constant iterator to the beginning of the information about the named allocations performed in this segment manager
const_named_iterator named_end() const;
Returns a constant iterator to the end of the information about the named allocations performed in this segment manager
const_unique_iterator unique_begin() const;
Returns a constant iterator to the beginning of the information about the unique allocations performed in this segment manager
const_unique_iterator unique_end() const;
Returns a constant iterator to the end of the information about the unique allocations performed in this segment manager
template<typename T> allocator< T >::type get_allocator();
Returns an instance of the default allocator for type T initialized that allocates memory from this segment manager.
template<typename T> deleter< T >::type get_deleter();
Returns an instance of the default deleter for type T that will delete an object constructed in this segment manager.
segment_manager
public static functionstemplate<typename T> static const CharType * get_instance_name(const T * ptr);
Returns the name of an object created with construct/find_or_construct functions. Does not throw
template<typename T> static size_type get_instance_length(const T * ptr);
Returns the length of an object created with construct/find_or_construct functions. Does not throw.
template<typename T> static instance_type get_instance_type(const T * ptr);
Returns is the the name of an object created with construct/find_or_construct functions. Does not throw
static size_type get_min_size();
Obtains the minimum size needed by the segment manager