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Hello, This is a patch for the bitmap allocator. The issues touched are: 1. Alignment problems as noticed by Paolo Carlini. Now, all memory blocks(requests) are aligned to 8 bytes. I have made the following assumptions: Consider a x86-linux system, where int is 32 bits and so is void* or for that matter _Tp*. Now, whatever alignment operator new() returns, that starting_address%8 would be the same as the result of the operation of the return from bitmap_allocator.allocate()%8. 2. Formatting fixes => All lines should be of width <= 80 chars. 3. Other minor fixes like further uglification and tending towards C++STYLE. 4. It now compiles fine when configured as the default, but there are many linking errors during the final phase of bootstrap. Please look into this if possible :-( Thanks! -- -Dhruv Matani. http://www.geocities.com/dhruvbird/ Proud to be a Vegetarian. http://www.vegetarianstarterkit.com/ http://www.vegkids.com/vegkids/index.html
// Bitmapped Allocator. -*- C++ -*- // Copyright (C) 2004 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 2, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License along // with this library; see the file COPYING. If not, write to the Free // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, // USA. // As a special exception, you may use this file as part of a free software // library without restriction. Specifically, if other files instantiate // templates or use macros or inline functions from this file, or you compile // this file and link it with other files to produce an executable, this // file does not by itself cause the resulting executable to be covered by // the GNU General Public License. This exception does not however // invalidate any other reasons why the executable file might be covered by // the GNU General Public License. #if !defined _BITMAP_ALLOCATOR_H #define _BITMAP_ALLOCATOR_H 1 #include <cstddef> // For std::size_t, and ptrdiff_t. #include <utility> //For std::pair. #include <vector> // For the free list of exponentially growing memory blocks. At max, // size of the vector should be not more than the number of bits in an // integer or an unsigned integer. #include <functional> // For greater_equal, and less_equal. #include <new> // For operator new. #include <bits/gthr.h> // For __gthread_mutex_t, __gthread_mutex_lock and __gthread_mutex_unlock. #include <ext/new_allocator.h> // For __gnu_cxx::new_allocator for std::vector. #define _BALLOC_SANITY_CHECK 0 #if _BALLOC_SANITY_CHECK == 1 #include <cassert> #define _BALLOC_ASSERT(_EXPR) assert(_EXPR) #else #define _BALLOC_ASSERT(_EXPR) #endif namespace __gnu_cxx { namespace { #if defined __GTHREADS bool const __threads_enabled = __gthread_active_p(); #endif } #if defined __GTHREADS class _Mutex { __gthread_mutex_t _M_mut; // Prevent Copying and assignment. _Mutex(_Mutex const&); _Mutex& operator=(_Mutex const&); public: _Mutex() { if (__threads_enabled) { #if !defined __GTHREAD_MUTEX_INIT __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mut); #else __gthread_mutex_t __mtemp = __GTHREAD_MUTEX_INIT; _M_mut = __mtemp; #endif } } ~_Mutex() { // Gthreads does not define a Mutex Destruction Function. } __gthread_mutex_t *_M_get() { return &_M_mut; } }; class _Lock { _Mutex* _M_pmt; bool _M_locked; // Prevent Copying and assignment. _Lock(_Lock const&); _Lock& operator=(_Lock const&); public: _Lock(_Mutex* __mptr) : _M_pmt(__mptr), _M_locked(false) { } void _M_lock() { if (__threads_enabled) { _M_locked = true; __gthread_mutex_lock(_M_pmt->_M_get()); } } void _M_unlock() { if (__threads_enabled) { if (__builtin_expect(_M_locked, true)) { __gthread_mutex_unlock(_M_pmt->_M_get()); _M_locked = false; } } } ~_Lock() { } }; class _Auto_Lock { _Mutex* _M_pmt; // Prevent Copying and assignment. _Auto_Lock(_Auto_Lock const&); _Auto_Lock& operator=(_Auto_Lock const&); void _M_lock() { if (__threads_enabled) __gthread_mutex_lock(_M_pmt->_M_get()); } void _M_unlock() { if (__threads_enabled) __gthread_mutex_unlock(_M_pmt->_M_get()); } public: _Auto_Lock(_Mutex* __mptr) { this->_M_lock(); } ~_Auto_Lock() { this->_M_unlock(); } }; #endif namespace __aux_balloc { static const unsigned int _Bits_Per_Byte = 8; static const unsigned int _Bits_Per_Block = sizeof(unsigned int) * _Bits_Per_Byte; template<typename _ForwardIterator, typename _Tp, typename _Compare> _ForwardIterator __balloc_lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __val, _Compare __comp) { typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType; typedef typename iterator_traits<_ForwardIterator>::difference_type _DistanceType; _DistanceType __len = std::distance(__first, __last); _DistanceType __half; _ForwardIterator __middle; while (__len > 0) { __half = __len >> 1; __middle = __first; std::advance(__middle, __half); if (__comp(*__middle, __val)) { __first = __middle; ++__first; __len = __len - __half - 1; } else __len = __half; } return __first; } template<typename _InputIterator, typename _Predicate> inline _InputIterator __balloc_find_if(_InputIterator __first, _InputIterator __last, _Predicate __pred) { while (__first != __last && !__pred(*__first)) ++__first; return __first; } template <typename _Addr_Pair_t> inline size_t __balloc_num_blocks(_Addr_Pair_t __ap) { return (__ap.second - __ap.first) + 1; } template <typename _Addr_Pair_t> inline size_t __balloc_num_bit_maps(_Addr_Pair_t __ap) { return __balloc_num_blocks(__ap) / _Bits_Per_Block; } // _Tp should be a pointer type. template <typename _Tp> class _Inclusive_between : public std::unary_function<typename std::pair<_Tp, _Tp>, bool> { typedef _Tp pointer; pointer _M_ptr_value; typedef typename std::pair<_Tp, _Tp> _Block_pair; public: _Inclusive_between(pointer __ptr) : _M_ptr_value(__ptr) { } bool operator()(_Block_pair __bp) const throw() { if (std::less_equal<pointer>()(_M_ptr_value, __bp.second) && std::greater_equal<pointer>()(_M_ptr_value, __bp.first)) return true; else return false; } }; // Used to pass a Functor to functions by reference. template <typename _Functor> class _Functor_Ref : public std::unary_function<typename _Functor::argument_type, typename _Functor::result_type> { _Functor& _M_fref; public: typedef typename _Functor::argument_type argument_type; typedef typename _Functor::result_type result_type; _Functor_Ref(_Functor& __fref) : _M_fref(__fref) { } result_type operator()(argument_type __arg) { return _M_fref(__arg); } }; // _Tp should be a pointer type, and _Alloc is the Allocator for // the vector. template <typename _Tp, typename _Alloc> class _Ffit_finder : public std::unary_function<typename std::pair<_Tp, _Tp>, bool> { typedef typename std::vector<std::pair<_Tp, _Tp>, _Alloc> _BPVector; typedef typename _BPVector::difference_type _Counter_type; typedef typename std::pair<_Tp, _Tp> _Block_pair; unsigned int* _M_pbitmap; unsigned int _M_data_offset; public: _Ffit_finder() : _M_pbitmap(0), _M_data_offset(0) { } bool operator()(_Block_pair __bp) throw() { // Set the _rover to the last unsigned integer, which is the // bitmap to the first free block. Thus, the bitmaps are in exact // reverse order of the actual memory layout. So, we count down // the bimaps, which is the same as moving up the memory. // If the used count stored at the start of the Bit Map headers // is equal to the number of Objects that the current Block can // store, then there is definitely no space for another single // object, so just return false. _Counter_type __diff = __gnu_cxx::__aux_balloc::__balloc_num_bit_maps(__bp); _BALLOC_ASSERT(*(reinterpret_cast<unsigned int*>(__bp.first) - (__diff + 1)) <= __gnu_cxx::__aux_balloc::__balloc_num_blocks (__bp)); if (*(reinterpret_cast<unsigned int*>(__bp.first) - (__diff + 1)) == __gnu_cxx::__aux_balloc::__balloc_num_blocks(__bp)) return false; unsigned int* __rover = reinterpret_cast<unsigned int*>(__bp.first) - 1; for (_Counter_type __i = 0; __i < __diff; ++__i) { _M_data_offset = __i; if (*__rover) { _M_pbitmap = __rover; return true; } --__rover; } return false; } unsigned int* _M_get() { return _M_pbitmap; } unsigned int _M_offset() { return _M_data_offset * _Bits_Per_Block; } }; // _Tp should be a pointer type. template <typename _Tp, typename _Alloc> class _Bit_map_counter { typedef typename std::vector<std::pair<_Tp, _Tp>, _Alloc> _BPVector; typedef typename _BPVector::size_type _Index_type; typedef _Tp pointer; _BPVector& _M_vbp; unsigned int* _M_curr_bmap; unsigned int* _M_last_bmap_in_block; _Index_type _M_curr_index; public: // Use the 2nd parameter with care. Make sure that such an entry // exists in the vector before passing that particular index to // this ctor. _Bit_map_counter(_BPVector& Rvbp, int __index = -1) : _M_vbp(Rvbp) { this->_M_reset(__index); } void _M_reset(int __index = -1) throw() { if (__index == -1) { _M_curr_bmap = 0; _M_curr_index = static_cast<_Index_type>(-1); return; } _M_curr_index = __index; _M_curr_bmap = reinterpret_cast<unsigned int*> (_M_vbp[_M_curr_index].first) - 1; _BALLOC_ASSERT(__index <= (int)_M_vbp.size() - 1); _M_last_bmap_in_block = _M_curr_bmap - ((_M_vbp[_M_curr_index].second - _M_vbp[_M_curr_index].first + 1) / _Bits_Per_Block - 1); } // Dangerous Function! Use with extreme care. Pass to this // function ONLY those values that are known to be correct, // otherwise this will mess up big time. void _M_set_internal_bit_map(unsigned int* __new_internal_marker) throw() { _M_curr_bmap = __new_internal_marker; } bool _M_finished() const throw() { return(_M_curr_bmap == 0); } _Bit_map_counter& operator++() throw() { if (_M_curr_bmap == _M_last_bmap_in_block) { if (++_M_curr_index == _M_vbp.size()) { _M_curr_bmap = 0; } else { this->_M_reset(_M_curr_index); } } else { --_M_curr_bmap; } return *this; } unsigned int* _M_get() { return _M_curr_bmap; } pointer _M_base() { return _M_vbp[_M_curr_index].first; } unsigned int _M_offset() { return _Bits_Per_Block * ((reinterpret_cast<unsigned int*>(this->_M_base()) - _M_curr_bmap) - 1); } unsigned int _M_where() { return _M_curr_index; } }; } // Generic Version of the bsf instruction. typedef unsigned int _Bit_map_type; static inline unsigned int _Bit_scan_forward(register _Bit_map_type __num) { return static_cast<unsigned int>(__builtin_ctz(__num)); } struct _OOM_handler { static std::new_handler _S_old_handler; static bool _S_handled_oom; typedef void(*_FL_clear_proc)(void); static _FL_clear_proc _S_oom_fcp; _OOM_handler(_FL_clear_proc __fcp) { _S_oom_fcp = __fcp; _S_old_handler = std::set_new_handler(_S_handle_oom_proc); _S_handled_oom = false; } static void _S_handle_oom_proc() { _S_oom_fcp(); std::set_new_handler(_S_old_handler); _S_handled_oom = true; } ~_OOM_handler() { if (!_S_handled_oom) std::set_new_handler(_S_old_handler); } }; std::new_handler _OOM_handler::_S_old_handler; bool _OOM_handler::_S_handled_oom = false; _OOM_handler::_FL_clear_proc _OOM_handler::_S_oom_fcp = 0; class _BA_free_list_store { struct _LT_pointer_compare { template <typename _Tp> bool operator()(_Tp* __pt, _Tp const& __crt) const throw() { return *__pt < __crt; } }; #if defined __GTHREADS static _Mutex _S_bfl_mutex; #endif static std::vector<unsigned int*, __gnu_cxx::new_allocator<unsigned int*> > _S_free_list; typedef std::vector<unsigned int*, __gnu_cxx::new_allocator<unsigned int*> > ::iterator _FLIter; static void _S_validate_free_list(unsigned int* __addr) throw() { const unsigned int __max_size = 64; if (_S_free_list.size() >= __max_size) { // Ok, the threshold value has been reached. // We determine which block to remove from the list of free // blocks. if (*__addr >= *_S_free_list.back()) { // Ok, the new block is greater than or equal to the last // block in the list of free blocks. We just free the new // block. operator delete((void*)__addr); return; } else { // Deallocate the last block in the list of free lists, and // insert the new one in it's correct position. operator delete((void*)_S_free_list.back()); _S_free_list.pop_back(); } } // Just add the block to the list of free lists // unconditionally. _FLIter __temp = __gnu_cxx::__aux_balloc::__balloc_lower_bound (_S_free_list.begin(), _S_free_list.end(), *__addr, _LT_pointer_compare()); // We may insert the new free list before _temp; _S_free_list.insert(__temp, __addr); } static bool _S_should_i_give(unsigned int __block_size, unsigned int __required_size) throw() { const unsigned int __max_wastage_percentage = 36; if (__block_size >= __required_size && (((__block_size - __required_size) * 100 / __block_size) < __max_wastage_percentage)) return true; else return false; } public: typedef _BA_free_list_store _BFL_type; static inline void _S_insert_free_list(unsigned int* __addr) throw() { #if defined __GTHREADS _Auto_Lock __bfl_lock(&_S_bfl_mutex); #endif // Call _S_validate_free_list to decide what should be done with this // particular free list. _S_validate_free_list(--__addr); } static unsigned int* _S_get_free_list(unsigned int __sz) throw(std::bad_alloc) { #if defined __GTHREADS _Auto_Lock __bfl_lock(&_S_bfl_mutex); #endif _FLIter __temp = __gnu_cxx::__aux_balloc::__balloc_lower_bound (_S_free_list.begin(), _S_free_list.end(), __sz, _LT_pointer_compare()); if (__temp == _S_free_list.end() || !_S_should_i_give(**__temp, __sz)) { // We hold the lock because the OOM_Handler is a stateless // entity. _OOM_handler __set_handler(_BFL_type::_S_clear); unsigned int* __ret_val = reinterpret_cast<unsigned int*> (operator new(__sz + sizeof(unsigned int))); *__ret_val = __sz; return ++__ret_val; } else { unsigned int* __ret_val = *__temp; _S_free_list.erase(__temp); return ++__ret_val; } } // This function just clears the internal Free List, and gives back // all the memory to the OS. static void _S_clear() { #if defined __GTHREADS _Auto_Lock __bfl_lock(&_S_bfl_mutex); #endif _FLIter __iter = _S_free_list.begin(); while (__iter != _S_free_list.end()) { operator delete((void*)*__iter); ++__iter; } _S_free_list.clear(); } }; #if defined __GTHREADS _Mutex _BA_free_list_store::_S_bfl_mutex; #endif std::vector<unsigned int*, __gnu_cxx::new_allocator<unsigned int*> > _BA_free_list_store::_S_free_list; // Forward declare the class. template <typename _Tp> class bitmap_allocator; // Specialize for void: template <> class bitmap_allocator<void> { public: typedef void* pointer; typedef const void* const_pointer; // reference-to-void members are impossible. typedef void value_type; template <typename _Tp1> struct rebind { typedef bitmap_allocator<_Tp1> other; }; }; template <typename _Tp> class bitmap_allocator : private _BA_free_list_store { public: typedef size_t size_type; typedef ptrdiff_t difference_type; typedef _Tp* pointer; typedef const _Tp* const_pointer; typedef _Tp& reference; typedef const _Tp& const_reference; typedef _Tp value_type; template <typename _Tp1> struct rebind { typedef bitmap_allocator<_Tp1> other; }; private: static const unsigned int _Bits_Per_Byte = 8; static const unsigned int _Bits_Per_Block = sizeof(unsigned int) * _Bits_Per_Byte; template <unsigned int _BSize, unsigned int _Align_size> struct _Aligned_size { enum { __value = _BSize + (_BSize % _Align_size ? _Align_size - (_BSize % _Align_size) : 0) }; }; struct _Alloc_block { char __unused[_Aligned_size<sizeof(value_type), 8>::__value]; }; static inline void _S_bit_allocate(unsigned int* __pbmap, unsigned int __pos) throw() { unsigned int __mask = 1 << __pos; __mask = ~__mask; *__pbmap &= __mask; } static inline void _S_bit_free(unsigned int* __pbmap, unsigned int __pos) throw() { unsigned int __mask = 1 << __pos; *__pbmap |= __mask; } static inline void* _S_memory_get(size_t __sz) throw(std::bad_alloc) { return operator new(__sz); } static inline void _S_memory_put(void *__vptr) throw() { operator delete(__vptr); } typedef typename std::pair<_Alloc_block*, _Alloc_block*> _Block_pair; typedef typename __gnu_cxx::new_allocator<_Block_pair> _BPVec_allocator_type; typedef typename std::vector<_Block_pair, _BPVec_allocator_type> _BPVector; #if defined _BALLOC_SANITY_CHECK // Complexity: O(lg(N)). Where, N is the number of block of size // sizeof(value_type). static void _S_check_for_free_blocks() throw() { typedef typename __gnu_cxx::__aux_balloc::_Ffit_finder<_Alloc_block*, _BPVec_allocator_type> _FFF; _FFF __fff; typedef typename _BPVector::iterator _BPiter; _BPiter __bpi = __gnu_cxx::__aux_balloc::__balloc_find_if (_S_mem_blocks.begin(), _S_mem_blocks.end(), __gnu_cxx::__aux_balloc::_Functor_Ref<_FFF>(__fff)); _BALLOC_ASSERT(__bpi == _S_mem_blocks.end()); } #endif // Complexity: O(1), but internally depends upon the complexity of // the function _BA_free_list_store::_S_get_free_list. The part // where the bitmap headers are written is of worst case complexity: // O(X),where X is the number of blocks of size sizeof(value_type) // within the newly acquired block. Having a tight bound. static void _S_refill_pool() throw(std::bad_alloc) { #if defined _BALLOC_SANITY_CHECK _S_check_for_free_blocks(); #endif const unsigned int __num_bit_maps = _S_block_size / _Bits_Per_Block; const unsigned int __size_to_allocate = sizeof(unsigned int) + _S_block_size * sizeof(_Alloc_block) + __num_bit_maps*sizeof(unsigned int); unsigned int* __temp = reinterpret_cast<unsigned int*> (_BA_free_list_store::_S_get_free_list(__size_to_allocate)); *__temp = 0; ++__temp; // The Header information goes at the Beginning of the Block. _Block_pair __bp = std::make_pair(reinterpret_cast<_Alloc_block*> (__temp + __num_bit_maps), reinterpret_cast<_Alloc_block*> (__temp + __num_bit_maps) + _S_block_size - 1); // Fill the Vector with this information. _S_mem_blocks.push_back(__bp); unsigned int __bit_mask = 0; // 0 Indicates all Allocated. __bit_mask = ~__bit_mask; // 1 Indicates all Free. for (unsigned int __i = 0; __i < __num_bit_maps; ++__i) __temp[__i] = __bit_mask; // On some implementations, operator new might throw bad_alloc, or // malloc might fail if the size passed is too large, therefore, we // limit the size passed to malloc or operator new. _S_block_size *= 2; } static _BPVector _S_mem_blocks; static unsigned int _S_block_size; static __gnu_cxx::__aux_balloc:: _Bit_map_counter<_Alloc_block*, _BPVec_allocator_type> _S_last_request; static typename _BPVector::size_type _S_last_dealloc_index; #if defined __GTHREADS static _Mutex _S_mut; #endif // Complexity: Worst case complexity is O(N), but that is hardly ever // hit. if and when this particular case is encountered, the next few // cases are guaranteed to have a worst case complexity of O(1)! // That's why this function performs very well on the average. you // can consider this function to be having a complexity refrred to // commonly as: Amortized Constant time. static pointer _S_allocate_single_object() { #if defined __GTHREADS _Auto_Lock __bit_lock(&_S_mut); #endif // The algorithm is something like this: The last_requst variable // points to the last accessed Bit Map. When such a condition // occurs, we try to find a free block in the current bitmap, or // succeeding bitmaps until the last bitmap is reached. If no free // block turns up, we resort to First Fit method. // WARNING: Do not re-order the condition in the while statement // below, because it relies on C++'s short-circuit // evaluation. The return from _S_last_request->_M_get() will NOT // be dereferenceable if _S_last_request->_M_finished() returns // true. This would inevitibly lead to a NULL pointer dereference // if tinkered with. while (_S_last_request._M_finished() == false && (*(_S_last_request._M_get()) == 0)) { _S_last_request.operator++(); } if (__builtin_expect(_S_last_request._M_finished() == true, false)) { // Fall Back to First Fit algorithm. typedef typename __gnu_cxx::__aux_balloc::_Ffit_finder<_Alloc_block*, _BPVec_allocator_type> _FFF; _FFF __fff; typedef typename _BPVector::iterator _BPiter; _BPiter __bpi = __gnu_cxx::__aux_balloc::__balloc_find_if (_S_mem_blocks.begin(), _S_mem_blocks.end(), __gnu_cxx::__aux_balloc::_Functor_Ref<_FFF>(__fff)); if (__bpi != _S_mem_blocks.end()) { // Search was successful. Ok, now mark the first bit from // the right as 0, meaning Allocated. This bit is obtained // by calling _M_get() on __fff. unsigned int __nz_bit = _Bit_scan_forward(*__fff._M_get()); _S_bit_allocate(__fff._M_get(), __nz_bit); _S_last_request._M_reset(__bpi - _S_mem_blocks.begin()); // Now, get the address of the bit we marked as allocated. pointer __ret_val = reinterpret_cast<pointer> (__bpi->first + __fff._M_offset() + __nz_bit); unsigned int* __puse_count = reinterpret_cast<unsigned int*>(__bpi->first) - (__gnu_cxx::__aux_balloc::__balloc_num_bit_maps (*__bpi) + 1); ++(*__puse_count); return __ret_val; } else { // Search was unsuccessful. We Add more memory to the pool // by calling _S_refill_pool(). _S_refill_pool(); // _M_Reset the _S_last_request structure to the first free // block's bit map. _S_last_request._M_reset(_S_mem_blocks.size() - 1); // Now, mark that bit as allocated. } } // _S_last_request holds a pointer to a valid bit map, that points // to a free block in memory. unsigned int __nz_bit = _Bit_scan_forward(*_S_last_request._M_get()); _S_bit_allocate(_S_last_request._M_get(), __nz_bit); pointer __ret_val = reinterpret_cast<pointer> (_S_last_request._M_base() + _S_last_request._M_offset() + __nz_bit); unsigned int* __puse_count = reinterpret_cast<unsigned int*> (_S_mem_blocks[_S_last_request._M_where()].first) - (__gnu_cxx::__aux_balloc:: __balloc_num_bit_maps(_S_mem_blocks[_S_last_request._M_where()]) + 1); ++(*__puse_count); return __ret_val; } // Complexity: O(lg(N)), but the worst case is hit quite often! I // need to do something about this. I'll be able to work on it, only // when I have some solid figures from a few real apps. static void _S_deallocate_single_object(pointer __p) throw() { #if defined __GTHREADS _Auto_Lock __bit_lock(&_S_mut); #endif _Alloc_block* __real_p = reinterpret_cast<_Alloc_block*>(__p); typedef typename _BPVector::iterator _Iterator; typedef typename _BPVector::difference_type _Difference_type; _Difference_type __diff; int __displacement; _BALLOC_ASSERT(_S_last_dealloc_index >= 0); if (__gnu_cxx::__aux_balloc::_Inclusive_between<_Alloc_block*> (__real_p) (_S_mem_blocks[_S_last_dealloc_index])) { _BALLOC_ASSERT(_S_last_dealloc_index <= _S_mem_blocks.size() - 1); // Initial Assumption was correct! __diff = _S_last_dealloc_index; __displacement = __real_p - _S_mem_blocks[__diff].first; } else { _Iterator _iter = __gnu_cxx::__aux_balloc::__balloc_find_if(_S_mem_blocks.begin(), _S_mem_blocks.end(), __gnu_cxx::__aux_balloc:: _Inclusive_between<_Alloc_block*>(__real_p)); _BALLOC_ASSERT(_iter != _S_mem_blocks.end()); __diff = _iter - _S_mem_blocks.begin(); __displacement = __real_p - _S_mem_blocks[__diff].first; _S_last_dealloc_index = __diff; } // Get the position of the iterator that has been found. const unsigned int __rotate = __displacement % _Bits_Per_Block; unsigned int* __bit_mapC = reinterpret_cast<unsigned int*>(_S_mem_blocks[__diff].first) - 1; __bit_mapC -= (__displacement / _Bits_Per_Block); _S_bit_free(__bit_mapC, __rotate); unsigned int* __puse_count = reinterpret_cast<unsigned int*> (_S_mem_blocks[__diff].first) - (__gnu_cxx::__aux_balloc:: __balloc_num_bit_maps(_S_mem_blocks[__diff]) + 1); _BALLOC_ASSERT(*__puse_count != 0); --(*__puse_count); if (__builtin_expect(*__puse_count == 0, false)) { _S_block_size /= 2; // We may safely remove this block. _Block_pair __bp = _S_mem_blocks[__diff]; _S_insert_free_list(__puse_count); _S_mem_blocks.erase(_S_mem_blocks.begin() + __diff); // We reset the _S_last_request variable to reflect the erased // block. We do this to protect future requests after the last // block has been removed from a particular memory Chunk, // which in turn has been returned to the free list, and // hence had been erased from the vector, so the size of the // vector gets reduced by 1. if ((_Difference_type)_S_last_request._M_where() >= __diff--) { _S_last_request._M_reset(__diff); } // If the Index into the vector of the region of memory that // might hold the next address that will be passed to // deallocated may have been invalidated due to the above // erase procedure being called on the vector, hence we try // to restore this invariant too. if (_S_last_dealloc_index >= _S_mem_blocks.size()) { _S_last_dealloc_index =(__diff != -1 ? __diff : 0); _BALLOC_ASSERT(_S_last_dealloc_index >= 0); } } } public: bitmap_allocator() throw() { } bitmap_allocator(const bitmap_allocator&) { } template <typename _Tp1> bitmap_allocator(const bitmap_allocator<_Tp1>&) throw() { } ~bitmap_allocator() throw() { } // Complexity: O(1), but internally the complexity depends upon the // complexity of the function(s) _S_allocate_single_object and // _S_memory_get. pointer allocate(size_type __n) { if (__builtin_expect(__n == 1, true)) return _S_allocate_single_object(); else return reinterpret_cast<pointer> (_S_memory_get(__n * sizeof(value_type))); } pointer allocate(size_type __n, typename bitmap_allocator<void>::const_pointer) { return allocate(__n); } void deallocate(pointer __p, size_type __n) throw() { if (__builtin_expect(__n == 1, true)) _S_deallocate_single_object(__p); else _S_memory_put(__p); } pointer address(reference __r) const { return &__r; } const_pointer address(const_reference __r) const { return &__r; } size_type max_size() const throw() { return(size_type()-1)/sizeof(value_type); } void construct(pointer __p, const_reference __data) { ::new(__p) value_type(__data); } void destroy(pointer __p) { __p->~value_type(); } }; template <typename _Tp> typename bitmap_allocator<_Tp>::_BPVector bitmap_allocator<_Tp>::_S_mem_blocks; template <typename _Tp> unsigned int bitmap_allocator<_Tp>::_S_block_size = bitmap_allocator<_Tp>::_Bits_Per_Block; template <typename _Tp> typename __gnu_cxx::bitmap_allocator<_Tp>::_BPVector::size_type bitmap_allocator<_Tp>::_S_last_dealloc_index = 0; template <typename _Tp> __gnu_cxx::__aux_balloc::_Bit_map_counter <typename bitmap_allocator<_Tp>::_Alloc_block*, typename bitmap_allocator<_Tp>::_BPVec_allocator_type> bitmap_allocator<_Tp>::_S_last_request(_S_mem_blocks); #if defined __GTHREADS template <typename _Tp> __gnu_cxx::_Mutex bitmap_allocator<_Tp>::_S_mut; #endif template <typename _Tp1, typename _Tp2> bool operator==(const bitmap_allocator<_Tp1>&, const bitmap_allocator<_Tp2>&) throw() { return true; } template <typename _Tp1, typename _Tp2> bool operator!=(const bitmap_allocator<_Tp1>&, const bitmap_allocator<_Tp2>&) throw() { return false; } } #endif //_BITMAP_ALLOCATOR_H
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