1 // Bitmap Allocator. -*- C++ -*-
3 // Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
4 // Free Software Foundation, Inc.
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 3, or (at your option)
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
17 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 // <http://www.gnu.org/licenses/>.
26 /** @file ext/bitmap_allocator.h
27 * This file is a GNU extension to the Standard C++ Library.
30 #ifndef _BITMAP_ALLOCATOR_H
31 #define _BITMAP_ALLOCATOR_H 1
33 #include <utility> // For std::pair.
34 #include <bits/functexcept.h> // For __throw_bad_alloc().
35 #include <functional> // For greater_equal, and less_equal.
36 #include <new> // For operator new.
37 #include <debug/debug.h> // _GLIBCXX_DEBUG_ASSERT
38 #include <ext/concurrence.h>
39 #include <bits/move.h>
41 /** @brief The constant in the expression below is the alignment
44 #define _BALLOC_ALIGN_BYTES 8
46 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
53 /** @class __mini_vector bitmap_allocator.h bitmap_allocator.h
55 * @brief __mini_vector<> is a stripped down version of the
56 * full-fledged std::vector<>.
58 * It is to be used only for built-in types or PODs. Notable
62 * 1. Not all accessor functions are present.
63 * 2. Used ONLY for PODs.
64 * 3. No Allocator template argument. Uses ::operator new() to get
65 * memory, and ::operator delete() to free it.
66 * Caveat: The dtor does NOT free the memory allocated, so this a
67 * memory-leaking vector!
69 template<typename _Tp>
72 __mini_vector(const __mini_vector&);
73 __mini_vector& operator=(const __mini_vector&);
76 typedef _Tp value_type;
78 typedef _Tp& reference;
79 typedef const _Tp& const_reference;
80 typedef size_t size_type;
81 typedef ptrdiff_t difference_type;
82 typedef pointer iterator;
87 pointer _M_end_of_storage;
90 _M_space_left() const throw()
91 { return _M_end_of_storage - _M_finish; }
94 allocate(size_type __n)
95 { return static_cast<pointer>(::operator new(__n * sizeof(_Tp))); }
98 deallocate(pointer __p, size_type)
99 { ::operator delete(__p); }
102 // Members used: size(), push_back(), pop_back(),
103 // insert(iterator, const_reference), erase(iterator),
104 // begin(), end(), back(), operator[].
107 : _M_start(0), _M_finish(0), _M_end_of_storage(0) { }
111 { return _M_finish - _M_start; }
114 begin() const throw()
115 { return this->_M_start; }
119 { return this->_M_finish; }
123 { return *(this->end() - 1); }
126 operator[](const size_type __pos) const throw()
127 { return this->_M_start[__pos]; }
130 insert(iterator __pos, const_reference __x);
133 push_back(const_reference __x)
135 if (this->_M_space_left())
141 this->insert(this->end(), __x);
146 { --this->_M_finish; }
149 erase(iterator __pos) throw();
153 { this->_M_finish = this->_M_start; }
156 // Out of line function definitions.
157 template<typename _Tp>
158 void __mini_vector<_Tp>::
159 insert(iterator __pos, const_reference __x)
161 if (this->_M_space_left())
163 size_type __to_move = this->_M_finish - __pos;
164 iterator __dest = this->end();
165 iterator __src = this->end() - 1;
171 --__dest; --__src; --__to_move;
177 size_type __new_size = this->size() ? this->size() * 2 : 1;
178 iterator __new_start = this->allocate(__new_size);
179 iterator __first = this->begin();
180 iterator __start = __new_start;
181 while (__first != __pos)
184 ++__start; ++__first;
188 while (__first != this->end())
191 ++__start; ++__first;
194 this->deallocate(this->_M_start, this->size());
196 this->_M_start = __new_start;
197 this->_M_finish = __start;
198 this->_M_end_of_storage = this->_M_start + __new_size;
202 template<typename _Tp>
203 void __mini_vector<_Tp>::
204 erase(iterator __pos) throw()
206 while (__pos + 1 != this->end())
215 template<typename _Tp>
216 struct __mv_iter_traits
218 typedef typename _Tp::value_type value_type;
219 typedef typename _Tp::difference_type difference_type;
222 template<typename _Tp>
223 struct __mv_iter_traits<_Tp*>
225 typedef _Tp value_type;
226 typedef ptrdiff_t difference_type;
232 bits_per_block = sizeof(size_t) * size_t(bits_per_byte)
235 template<typename _ForwardIterator, typename _Tp, typename _Compare>
237 __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
238 const _Tp& __val, _Compare __comp)
240 typedef typename __mv_iter_traits<_ForwardIterator>::value_type
242 typedef typename __mv_iter_traits<_ForwardIterator>::difference_type
245 _DistanceType __len = __last - __first;
246 _DistanceType __half;
247 _ForwardIterator __middle;
254 if (__comp(*__middle, __val))
258 __len = __len - __half - 1;
266 /** @brief The number of Blocks pointed to by the address pair
267 * passed to the function.
269 template<typename _AddrPair>
271 __num_blocks(_AddrPair __ap)
272 { return (__ap.second - __ap.first) + 1; }
274 /** @brief The number of Bit-maps pointed to by the address pair
275 * passed to the function.
277 template<typename _AddrPair>
279 __num_bitmaps(_AddrPair __ap)
280 { return __num_blocks(__ap) / size_t(bits_per_block); }
282 // _Tp should be a pointer type.
283 template<typename _Tp>
284 class _Inclusive_between
285 : public std::unary_function<typename std::pair<_Tp, _Tp>, bool>
288 pointer _M_ptr_value;
289 typedef typename std::pair<_Tp, _Tp> _Block_pair;
292 _Inclusive_between(pointer __ptr) : _M_ptr_value(__ptr)
296 operator()(_Block_pair __bp) const throw()
298 if (std::less_equal<pointer>()(_M_ptr_value, __bp.second)
299 && std::greater_equal<pointer>()(_M_ptr_value, __bp.first))
306 // Used to pass a Functor to functions by reference.
307 template<typename _Functor>
309 : public std::unary_function<typename _Functor::argument_type,
310 typename _Functor::result_type>
315 typedef typename _Functor::argument_type argument_type;
316 typedef typename _Functor::result_type result_type;
318 _Functor_Ref(_Functor& __fref) : _M_fref(__fref)
322 operator()(argument_type __arg)
323 { return _M_fref(__arg); }
326 /** @class _Ffit_finder bitmap_allocator.h bitmap_allocator.h
328 * @brief The class which acts as a predicate for applying the
329 * first-fit memory allocation policy for the bitmap allocator.
331 // _Tp should be a pointer type, and _Alloc is the Allocator for
333 template<typename _Tp>
335 : public std::unary_function<typename std::pair<_Tp, _Tp>, bool>
337 typedef typename std::pair<_Tp, _Tp> _Block_pair;
338 typedef typename __detail::__mini_vector<_Block_pair> _BPVector;
339 typedef typename _BPVector::difference_type _Counter_type;
342 _Counter_type _M_data_offset;
345 _Ffit_finder() : _M_pbitmap(0), _M_data_offset(0)
349 operator()(_Block_pair __bp) throw()
351 // Set the _rover to the last physical location bitmap,
352 // which is the bitmap which belongs to the first free
353 // block. Thus, the bitmaps are in exact reverse order of
354 // the actual memory layout. So, we count down the bitmaps,
355 // which is the same as moving up the memory.
357 // If the used count stored at the start of the Bit Map headers
358 // is equal to the number of Objects that the current Block can
359 // store, then there is definitely no space for another single
360 // object, so just return false.
361 _Counter_type __diff = __detail::__num_bitmaps(__bp);
363 if (*(reinterpret_cast<size_t*>
364 (__bp.first) - (__diff + 1)) == __detail::__num_blocks(__bp))
367 size_t* __rover = reinterpret_cast<size_t*>(__bp.first) - 1;
369 for (_Counter_type __i = 0; __i < __diff; ++__i)
371 _M_data_offset = __i;
374 _M_pbitmap = __rover;
383 _M_get() const throw()
384 { return _M_pbitmap; }
387 _M_offset() const throw()
388 { return _M_data_offset * size_t(bits_per_block); }
391 /** @class _Bitmap_counter bitmap_allocator.h bitmap_allocator.h
393 * @brief The bitmap counter which acts as the bitmap
394 * manipulator, and manages the bit-manipulation functions and
395 * the searching and identification functions on the bit-map.
397 // _Tp should be a pointer type.
398 template<typename _Tp>
399 class _Bitmap_counter
402 __detail::__mini_vector<typename std::pair<_Tp, _Tp> > _BPVector;
403 typedef typename _BPVector::size_type _Index_type;
407 size_t* _M_curr_bmap;
408 size_t* _M_last_bmap_in_block;
409 _Index_type _M_curr_index;
412 // Use the 2nd parameter with care. Make sure that such an
413 // entry exists in the vector before passing that particular
414 // index to this ctor.
415 _Bitmap_counter(_BPVector& Rvbp, long __index = -1) : _M_vbp(Rvbp)
416 { this->_M_reset(__index); }
419 _M_reset(long __index = -1) throw()
424 _M_curr_index = static_cast<_Index_type>(-1);
428 _M_curr_index = __index;
429 _M_curr_bmap = reinterpret_cast<size_t*>
430 (_M_vbp[_M_curr_index].first) - 1;
432 _GLIBCXX_DEBUG_ASSERT(__index <= (long)_M_vbp.size() - 1);
434 _M_last_bmap_in_block = _M_curr_bmap
435 - ((_M_vbp[_M_curr_index].second
436 - _M_vbp[_M_curr_index].first + 1)
437 / size_t(bits_per_block) - 1);
440 // Dangerous Function! Use with extreme care. Pass to this
441 // function ONLY those values that are known to be correct,
442 // otherwise this will mess up big time.
444 _M_set_internal_bitmap(size_t* __new_internal_marker) throw()
445 { _M_curr_bmap = __new_internal_marker; }
448 _M_finished() const throw()
449 { return(_M_curr_bmap == 0); }
454 if (_M_curr_bmap == _M_last_bmap_in_block)
456 if (++_M_curr_index == _M_vbp.size())
459 this->_M_reset(_M_curr_index);
467 _M_get() const throw()
468 { return _M_curr_bmap; }
471 _M_base() const throw()
472 { return _M_vbp[_M_curr_index].first; }
475 _M_offset() const throw()
477 return size_t(bits_per_block)
478 * ((reinterpret_cast<size_t*>(this->_M_base())
479 - _M_curr_bmap) - 1);
483 _M_where() const throw()
484 { return _M_curr_index; }
487 /** @brief Mark a memory address as allocated by re-setting the
488 * corresponding bit in the bit-map.
491 __bit_allocate(size_t* __pbmap, size_t __pos) throw()
493 size_t __mask = 1 << __pos;
498 /** @brief Mark a memory address as free by setting the
499 * corresponding bit in the bit-map.
502 __bit_free(size_t* __pbmap, size_t __pos) throw()
504 size_t __mask = 1 << __pos;
507 } // namespace __detail
509 /** @brief Generic Version of the bsf instruction.
512 _Bit_scan_forward(size_t __num)
513 { return static_cast<size_t>(__builtin_ctzl(__num)); }
515 /** @class free_list bitmap_allocator.h bitmap_allocator.h
517 * @brief The free list class for managing chunks of memory to be
518 * given to and returned by the bitmap_allocator.
523 typedef size_t* value_type;
524 typedef __detail::__mini_vector<value_type> vector_type;
525 typedef vector_type::iterator iterator;
526 typedef __mutex __mutex_type;
529 struct _LT_pointer_compare
532 operator()(const size_t* __pui,
533 const size_t __cui) const throw()
534 { return *__pui < __cui; }
537 #if defined __GTHREADS
541 static __mutex_type _S_mutex;
549 static vector_type _S_free_list;
553 /** @brief Performs validation of memory based on their size.
555 * @param __addr The pointer to the memory block to be
558 * @detail Validates the memory block passed to this function and
559 * appropriately performs the action of managing the free list of
560 * blocks by adding this block to the free list or deleting this
561 * or larger blocks from the free list.
564 _M_validate(size_t* __addr) throw()
566 vector_type& __free_list = _M_get_free_list();
567 const vector_type::size_type __max_size = 64;
568 if (__free_list.size() >= __max_size)
570 // Ok, the threshold value has been reached. We determine
571 // which block to remove from the list of free blocks.
572 if (*__addr >= *__free_list.back())
574 // Ok, the new block is greater than or equal to the
575 // last block in the list of free blocks. We just free
577 ::operator delete(static_cast<void*>(__addr));
582 // Deallocate the last block in the list of free lists,
583 // and insert the new one in its correct position.
584 ::operator delete(static_cast<void*>(__free_list.back()));
585 __free_list.pop_back();
589 // Just add the block to the list of free lists unconditionally.
590 iterator __temp = __detail::__lower_bound
591 (__free_list.begin(), __free_list.end(),
592 *__addr, _LT_pointer_compare());
594 // We may insert the new free list before _temp;
595 __free_list.insert(__temp, __addr);
598 /** @brief Decides whether the wastage of memory is acceptable for
599 * the current memory request and returns accordingly.
601 * @param __block_size The size of the block available in the free
604 * @param __required_size The required size of the memory block.
606 * @return true if the wastage incurred is acceptable, else returns
610 _M_should_i_give(size_t __block_size,
611 size_t __required_size) throw()
613 const size_t __max_wastage_percentage = 36;
614 if (__block_size >= __required_size &&
615 (((__block_size - __required_size) * 100 / __block_size)
616 < __max_wastage_percentage))
623 /** @brief This function returns the block of memory to the
624 * internal free list.
626 * @param __addr The pointer to the memory block that was given
627 * by a call to the _M_get function.
630 _M_insert(size_t* __addr) throw()
632 #if defined __GTHREADS
633 __scoped_lock __bfl_lock(_M_get_mutex());
635 // Call _M_validate to decide what should be done with
636 // this particular free list.
637 this->_M_validate(reinterpret_cast<size_t*>(__addr) - 1);
638 // See discussion as to why this is 1!
641 /** @brief This function gets a block of memory of the specified
642 * size from the free list.
644 * @param __sz The size in bytes of the memory required.
646 * @return A pointer to the new memory block of size at least
647 * equal to that requested.
650 _M_get(size_t __sz) throw(std::bad_alloc);
652 /** @brief This function just clears the internal Free List, and
653 * gives back all the memory to the OS.
660 // Forward declare the class.
661 template<typename _Tp>
662 class bitmap_allocator;
664 // Specialize for void:
666 class bitmap_allocator<void>
669 typedef void* pointer;
670 typedef const void* const_pointer;
672 // Reference-to-void members are impossible.
673 typedef void value_type;
674 template<typename _Tp1>
677 typedef bitmap_allocator<_Tp1> other;
682 * @brief Bitmap Allocator, primary template.
683 * @ingroup allocators
685 template<typename _Tp>
686 class bitmap_allocator : private free_list
689 typedef size_t size_type;
690 typedef ptrdiff_t difference_type;
691 typedef _Tp* pointer;
692 typedef const _Tp* const_pointer;
693 typedef _Tp& reference;
694 typedef const _Tp& const_reference;
695 typedef _Tp value_type;
696 typedef free_list::__mutex_type __mutex_type;
698 template<typename _Tp1>
701 typedef bitmap_allocator<_Tp1> other;
705 template<size_t _BSize, size_t _AlignSize>
710 modulus = _BSize % _AlignSize,
711 value = _BSize + (modulus ? _AlignSize - (modulus) : 0)
717 char __M_unused[aligned_size<sizeof(value_type),
718 _BALLOC_ALIGN_BYTES>::value];
722 typedef typename std::pair<_Alloc_block*, _Alloc_block*> _Block_pair;
724 typedef typename __detail::__mini_vector<_Block_pair> _BPVector;
725 typedef typename _BPVector::iterator _BPiter;
727 template<typename _Predicate>
729 _S_find(_Predicate __p)
731 _BPiter __first = _S_mem_blocks.begin();
732 while (__first != _S_mem_blocks.end() && !__p(*__first))
737 #if defined _GLIBCXX_DEBUG
738 // Complexity: O(lg(N)). Where, N is the number of block of size
739 // sizeof(value_type).
741 _S_check_for_free_blocks() throw()
743 typedef typename __detail::_Ffit_finder<_Alloc_block*> _FFF;
744 _BPiter __bpi = _S_find(_FFF());
746 _GLIBCXX_DEBUG_ASSERT(__bpi == _S_mem_blocks.end());
750 /** @brief Responsible for exponentially growing the internal
753 * @throw std::bad_alloc. If memory can not be allocated.
755 * @detail Complexity: O(1), but internally depends upon the
756 * complexity of the function free_list::_M_get. The part where
757 * the bitmap headers are written has complexity: O(X),where X
758 * is the number of blocks of size sizeof(value_type) within
759 * the newly acquired block. Having a tight bound.
762 _S_refill_pool() throw(std::bad_alloc)
764 #if defined _GLIBCXX_DEBUG
765 _S_check_for_free_blocks();
768 const size_t __num_bitmaps = (_S_block_size
769 / size_t(__detail::bits_per_block));
770 const size_t __size_to_allocate = sizeof(size_t)
771 + _S_block_size * sizeof(_Alloc_block)
772 + __num_bitmaps * sizeof(size_t);
775 reinterpret_cast<size_t*>(this->_M_get(__size_to_allocate));
779 // The Header information goes at the Beginning of the Block.
781 std::make_pair(reinterpret_cast<_Alloc_block*>
782 (__temp + __num_bitmaps),
783 reinterpret_cast<_Alloc_block*>
784 (__temp + __num_bitmaps)
785 + _S_block_size - 1);
787 // Fill the Vector with this information.
788 _S_mem_blocks.push_back(__bp);
790 for (size_t __i = 0; __i < __num_bitmaps; ++__i)
791 __temp[__i] = ~static_cast<size_t>(0); // 1 Indicates all Free.
796 static _BPVector _S_mem_blocks;
797 static size_t _S_block_size;
798 static __detail::_Bitmap_counter<_Alloc_block*> _S_last_request;
799 static typename _BPVector::size_type _S_last_dealloc_index;
800 #if defined __GTHREADS
801 static __mutex_type _S_mut;
806 /** @brief Allocates memory for a single object of size
809 * @throw std::bad_alloc. If memory can not be allocated.
811 * @detail Complexity: Worst case complexity is O(N), but that
812 * is hardly ever hit. If and when this particular case is
813 * encountered, the next few cases are guaranteed to have a
814 * worst case complexity of O(1)! That's why this function
815 * performs very well on average. You can consider this
816 * function to have a complexity referred to commonly as:
817 * Amortized Constant time.
820 _M_allocate_single_object() throw(std::bad_alloc)
822 #if defined __GTHREADS
823 __scoped_lock __bit_lock(_S_mut);
826 // The algorithm is something like this: The last_request
827 // variable points to the last accessed Bit Map. When such a
828 // condition occurs, we try to find a free block in the
829 // current bitmap, or succeeding bitmaps until the last bitmap
830 // is reached. If no free block turns up, we resort to First
833 // WARNING: Do not re-order the condition in the while
834 // statement below, because it relies on C++'s short-circuit
835 // evaluation. The return from _S_last_request->_M_get() will
836 // NOT be dereference able if _S_last_request->_M_finished()
837 // returns true. This would inevitably lead to a NULL pointer
838 // dereference if tinkered with.
839 while (_S_last_request._M_finished() == false
840 && (*(_S_last_request._M_get()) == 0))
841 _S_last_request.operator++();
843 if (__builtin_expect(_S_last_request._M_finished() == true, false))
845 // Fall Back to First Fit algorithm.
846 typedef typename __detail::_Ffit_finder<_Alloc_block*> _FFF;
848 _BPiter __bpi = _S_find(__detail::_Functor_Ref<_FFF>(__fff));
850 if (__bpi != _S_mem_blocks.end())
852 // Search was successful. Ok, now mark the first bit from
853 // the right as 0, meaning Allocated. This bit is obtained
854 // by calling _M_get() on __fff.
855 size_t __nz_bit = _Bit_scan_forward(*__fff._M_get());
856 __detail::__bit_allocate(__fff._M_get(), __nz_bit);
858 _S_last_request._M_reset(__bpi - _S_mem_blocks.begin());
860 // Now, get the address of the bit we marked as allocated.
861 pointer __ret = reinterpret_cast<pointer>
862 (__bpi->first + __fff._M_offset() + __nz_bit);
863 size_t* __puse_count =
864 reinterpret_cast<size_t*>
865 (__bpi->first) - (__detail::__num_bitmaps(*__bpi) + 1);
872 // Search was unsuccessful. We Add more memory to the
873 // pool by calling _S_refill_pool().
876 // _M_Reset the _S_last_request structure to the first
877 // free block's bit map.
878 _S_last_request._M_reset(_S_mem_blocks.size() - 1);
880 // Now, mark that bit as allocated.
884 // _S_last_request holds a pointer to a valid bit map, that
885 // points to a free block in memory.
886 size_t __nz_bit = _Bit_scan_forward(*_S_last_request._M_get());
887 __detail::__bit_allocate(_S_last_request._M_get(), __nz_bit);
889 pointer __ret = reinterpret_cast<pointer>
890 (_S_last_request._M_base() + _S_last_request._M_offset() + __nz_bit);
892 size_t* __puse_count = reinterpret_cast<size_t*>
893 (_S_mem_blocks[_S_last_request._M_where()].first)
895 __num_bitmaps(_S_mem_blocks[_S_last_request._M_where()]) + 1);
901 /** @brief Deallocates memory that belongs to a single object of
904 * @detail Complexity: O(lg(N)), but the worst case is not hit
905 * often! This is because containers usually deallocate memory
906 * close to each other and this case is handled in O(1) time by
907 * the deallocate function.
910 _M_deallocate_single_object(pointer __p) throw()
912 #if defined __GTHREADS
913 __scoped_lock __bit_lock(_S_mut);
915 _Alloc_block* __real_p = reinterpret_cast<_Alloc_block*>(__p);
917 typedef typename _BPVector::iterator _Iterator;
918 typedef typename _BPVector::difference_type _Difference_type;
920 _Difference_type __diff;
923 _GLIBCXX_DEBUG_ASSERT(_S_last_dealloc_index >= 0);
925 __detail::_Inclusive_between<_Alloc_block*> __ibt(__real_p);
926 if (__ibt(_S_mem_blocks[_S_last_dealloc_index]))
928 _GLIBCXX_DEBUG_ASSERT(_S_last_dealloc_index
929 <= _S_mem_blocks.size() - 1);
931 // Initial Assumption was correct!
932 __diff = _S_last_dealloc_index;
933 __displacement = __real_p - _S_mem_blocks[__diff].first;
937 _Iterator _iter = _S_find(__ibt);
939 _GLIBCXX_DEBUG_ASSERT(_iter != _S_mem_blocks.end());
941 __diff = _iter - _S_mem_blocks.begin();
942 __displacement = __real_p - _S_mem_blocks[__diff].first;
943 _S_last_dealloc_index = __diff;
946 // Get the position of the iterator that has been found.
947 const size_t __rotate = (__displacement
948 % size_t(__detail::bits_per_block));
950 reinterpret_cast<size_t*>
951 (_S_mem_blocks[__diff].first) - 1;
952 __bitmapC -= (__displacement / size_t(__detail::bits_per_block));
954 __detail::__bit_free(__bitmapC, __rotate);
955 size_t* __puse_count = reinterpret_cast<size_t*>
956 (_S_mem_blocks[__diff].first)
957 - (__detail::__num_bitmaps(_S_mem_blocks[__diff]) + 1);
959 _GLIBCXX_DEBUG_ASSERT(*__puse_count != 0);
963 if (__builtin_expect(*__puse_count == 0, false))
967 // We can safely remove this block.
968 // _Block_pair __bp = _S_mem_blocks[__diff];
969 this->_M_insert(__puse_count);
970 _S_mem_blocks.erase(_S_mem_blocks.begin() + __diff);
972 // Reset the _S_last_request variable to reflect the
973 // erased block. We do this to protect future requests
974 // after the last block has been removed from a particular
975 // memory Chunk, which in turn has been returned to the
976 // free list, and hence had been erased from the vector,
977 // so the size of the vector gets reduced by 1.
978 if ((_Difference_type)_S_last_request._M_where() >= __diff--)
979 _S_last_request._M_reset(__diff);
981 // If the Index into the vector of the region of memory
982 // that might hold the next address that will be passed to
983 // deallocated may have been invalidated due to the above
984 // erase procedure being called on the vector, hence we
985 // try to restore this invariant too.
986 if (_S_last_dealloc_index >= _S_mem_blocks.size())
988 _S_last_dealloc_index =(__diff != -1 ? __diff : 0);
989 _GLIBCXX_DEBUG_ASSERT(_S_last_dealloc_index >= 0);
995 bitmap_allocator() throw()
998 bitmap_allocator(const bitmap_allocator&)
1001 template<typename _Tp1>
1002 bitmap_allocator(const bitmap_allocator<_Tp1>&) throw()
1005 ~bitmap_allocator() throw()
1009 allocate(size_type __n)
1011 if (__n > this->max_size())
1012 std::__throw_bad_alloc();
1014 if (__builtin_expect(__n == 1, true))
1015 return this->_M_allocate_single_object();
1018 const size_type __b = __n * sizeof(value_type);
1019 return reinterpret_cast<pointer>(::operator new(__b));
1024 allocate(size_type __n, typename bitmap_allocator<void>::const_pointer)
1025 { return allocate(__n); }
1028 deallocate(pointer __p, size_type __n) throw()
1030 if (__builtin_expect(__p != 0, true))
1032 if (__builtin_expect(__n == 1, true))
1033 this->_M_deallocate_single_object(__p);
1035 ::operator delete(__p);
1040 address(reference __r) const
1041 { return std::__addressof(__r); }
1044 address(const_reference __r) const
1045 { return std::__addressof(__r); }
1048 max_size() const throw()
1049 { return size_type(-1) / sizeof(value_type); }
1052 construct(pointer __p, const_reference __data)
1053 { ::new((void *)__p) value_type(__data); }
1055 #ifdef __GXX_EXPERIMENTAL_CXX0X__
1056 template<typename... _Args>
1058 construct(pointer __p, _Args&&... __args)
1059 { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); }
1063 destroy(pointer __p)
1064 { __p->~value_type(); }
1067 template<typename _Tp1, typename _Tp2>
1069 operator==(const bitmap_allocator<_Tp1>&,
1070 const bitmap_allocator<_Tp2>&) throw()
1073 template<typename _Tp1, typename _Tp2>
1075 operator!=(const bitmap_allocator<_Tp1>&,
1076 const bitmap_allocator<_Tp2>&) throw()
1079 // Static member definitions.
1080 template<typename _Tp>
1081 typename bitmap_allocator<_Tp>::_BPVector
1082 bitmap_allocator<_Tp>::_S_mem_blocks;
1084 template<typename _Tp>
1085 size_t bitmap_allocator<_Tp>::_S_block_size =
1086 2 * size_t(__detail::bits_per_block);
1088 template<typename _Tp>
1089 typename bitmap_allocator<_Tp>::_BPVector::size_type
1090 bitmap_allocator<_Tp>::_S_last_dealloc_index = 0;
1092 template<typename _Tp>
1093 __detail::_Bitmap_counter
1094 <typename bitmap_allocator<_Tp>::_Alloc_block*>
1095 bitmap_allocator<_Tp>::_S_last_request(_S_mem_blocks);
1097 #if defined __GTHREADS
1098 template<typename _Tp>
1099 typename bitmap_allocator<_Tp>::__mutex_type
1100 bitmap_allocator<_Tp>::_S_mut;
1103 _GLIBCXX_END_NAMESPACE