1 // Bitmap Allocator. -*- C++ -*-
3 // Copyright (C) 2004-2020 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
25 /** @file ext/bitmap_allocator.h
26 * This file is a GNU extension to the Standard C++ Library.
29 #ifndef _BITMAP_ALLOCATOR_H
30 #define _BITMAP_ALLOCATOR_H 1
32 #include <utility> // For std::pair.
33 #include <bits/functexcept.h> // For __throw_bad_alloc().
34 #include <functional> // For greater_equal, and less_equal.
35 #include <new> // For operator new.
36 #include <debug/debug.h> // _GLIBCXX_DEBUG_ASSERT
37 #include <ext/concurrence.h>
38 #include <bits/move.h>
40 /** @brief The constant in the expression below is the alignment
43 #define _BALLOC_ALIGN_BYTES 8
45 namespace __gnu_cxx
_GLIBCXX_VISIBILITY(default)
47 _GLIBCXX_BEGIN_NAMESPACE_VERSION
51 /** @class __mini_vector bitmap_allocator.h bitmap_allocator.h
53 * @brief __mini_vector<> is a stripped down version of the
54 * full-fledged std::vector<>.
56 * It is to be used only for built-in types or PODs. Notable
59 * 1. Not all accessor functions are present.
60 * 2. Used ONLY for PODs.
61 * 3. No Allocator template argument. Uses ::operator new() to get
62 * memory, and ::operator delete() to free it.
63 * Caveat: The dtor does NOT free the memory allocated, so this a
64 * memory-leaking vector!
66 template<typename _Tp
>
69 __mini_vector(const __mini_vector
&);
70 __mini_vector
& operator=(const __mini_vector
&);
73 typedef _Tp value_type
;
75 typedef _Tp
& reference
;
76 typedef const _Tp
& const_reference
;
77 typedef std::size_t size_type
;
78 typedef std::ptrdiff_t difference_type
;
79 typedef pointer iterator
;
84 pointer _M_end_of_storage
;
87 _M_space_left() const throw()
88 { return _M_end_of_storage
- _M_finish
; }
90 _GLIBCXX_NODISCARD pointer
91 allocate(size_type __n
)
92 { return static_cast<pointer
>(::operator new(__n
* sizeof(_Tp
))); }
95 deallocate(pointer __p
, size_type
)
96 { ::operator delete(__p
); }
99 // Members used: size(), push_back(), pop_back(),
100 // insert(iterator, const_reference), erase(iterator),
101 // begin(), end(), back(), operator[].
104 : _M_start(0), _M_finish(0), _M_end_of_storage(0) { }
108 { return _M_finish
- _M_start
; }
111 begin() const throw()
112 { return this->_M_start
; }
116 { return this->_M_finish
; }
120 { return *(this->end() - 1); }
123 operator[](const size_type __pos
) const throw()
124 { return this->_M_start
[__pos
]; }
127 insert(iterator __pos
, const_reference __x
);
130 push_back(const_reference __x
)
132 if (this->_M_space_left())
138 this->insert(this->end(), __x
);
143 { --this->_M_finish
; }
146 erase(iterator __pos
) throw();
150 { this->_M_finish
= this->_M_start
; }
153 // Out of line function definitions.
154 template<typename _Tp
>
155 void __mini_vector
<_Tp
>::
156 insert(iterator __pos
, const_reference __x
)
158 if (this->_M_space_left())
160 size_type __to_move
= this->_M_finish
- __pos
;
161 iterator __dest
= this->end();
162 iterator __src
= this->end() - 1;
168 --__dest
; --__src
; --__to_move
;
174 size_type __new_size
= this->size() ? this->size() * 2 : 1;
175 iterator __new_start
= this->allocate(__new_size
);
176 iterator __first
= this->begin();
177 iterator __start
= __new_start
;
178 while (__first
!= __pos
)
181 ++__start
; ++__first
;
185 while (__first
!= this->end())
188 ++__start
; ++__first
;
191 this->deallocate(this->_M_start
, this->size());
193 this->_M_start
= __new_start
;
194 this->_M_finish
= __start
;
195 this->_M_end_of_storage
= this->_M_start
+ __new_size
;
199 template<typename _Tp
>
200 void __mini_vector
<_Tp
>::
201 erase(iterator __pos
) throw()
203 while (__pos
+ 1 != this->end())
212 template<typename _Tp
>
213 struct __mv_iter_traits
215 typedef typename
_Tp::value_type value_type
;
216 typedef typename
_Tp::difference_type difference_type
;
219 template<typename _Tp
>
220 struct __mv_iter_traits
<_Tp
*>
222 typedef _Tp value_type
;
223 typedef std::ptrdiff_t difference_type
;
229 bits_per_block
= sizeof(std::size_t) * std::size_t(bits_per_byte
)
232 template<typename _ForwardIterator
, typename _Tp
, typename _Compare
>
234 __lower_bound(_ForwardIterator __first
, _ForwardIterator __last
,
235 const _Tp
& __val
, _Compare __comp
)
237 typedef typename __mv_iter_traits
<_ForwardIterator
>::difference_type
240 _DistanceType __len
= __last
- __first
;
241 _DistanceType __half
;
242 _ForwardIterator __middle
;
249 if (__comp(*__middle
, __val
))
253 __len
= __len
- __half
- 1;
261 /** @brief The number of Blocks pointed to by the address pair
262 * passed to the function.
264 template<typename _AddrPair
>
266 __num_blocks(_AddrPair __ap
)
267 { return (__ap
.second
- __ap
.first
) + 1; }
269 /** @brief The number of Bit-maps pointed to by the address pair
270 * passed to the function.
272 template<typename _AddrPair
>
274 __num_bitmaps(_AddrPair __ap
)
275 { return __num_blocks(__ap
) / std::size_t(bits_per_block
); }
277 // _Tp should be a pointer type.
278 template<typename _Tp
>
279 class _Inclusive_between
280 : public std::unary_function
<typename
std::pair
<_Tp
, _Tp
>, bool>
283 pointer _M_ptr_value
;
284 typedef typename
std::pair
<_Tp
, _Tp
> _Block_pair
;
287 _Inclusive_between(pointer __ptr
) : _M_ptr_value(__ptr
)
291 operator()(_Block_pair __bp
) const throw()
293 if (std::less_equal
<pointer
>()(_M_ptr_value
, __bp
.second
)
294 && std::greater_equal
<pointer
>()(_M_ptr_value
, __bp
.first
))
301 // Used to pass a Functor to functions by reference.
302 template<typename _Functor
>
304 : public std::unary_function
<typename
_Functor::argument_type
,
305 typename
_Functor::result_type
>
310 typedef typename
_Functor::argument_type argument_type
;
311 typedef typename
_Functor::result_type result_type
;
313 _Functor_Ref(_Functor
& __fref
) : _M_fref(__fref
)
317 operator()(argument_type __arg
)
318 { return _M_fref(__arg
); }
321 /** @class _Ffit_finder bitmap_allocator.h bitmap_allocator.h
323 * @brief The class which acts as a predicate for applying the
324 * first-fit memory allocation policy for the bitmap allocator.
326 // _Tp should be a pointer type, and _Alloc is the Allocator for
328 template<typename _Tp
>
330 : public std::unary_function
<typename
std::pair
<_Tp
, _Tp
>, bool>
332 typedef typename
std::pair
<_Tp
, _Tp
> _Block_pair
;
333 typedef typename
__detail::__mini_vector
<_Block_pair
> _BPVector
;
334 typedef typename
_BPVector::difference_type _Counter_type
;
336 std::size_t* _M_pbitmap
;
337 _Counter_type _M_data_offset
;
340 _Ffit_finder() : _M_pbitmap(0), _M_data_offset(0)
344 operator()(_Block_pair __bp
) throw()
347 // Set the _rover to the last physical location bitmap,
348 // which is the bitmap which belongs to the first free
349 // block. Thus, the bitmaps are in exact reverse order of
350 // the actual memory layout. So, we count down the bitmaps,
351 // which is the same as moving up the memory.
353 // If the used count stored at the start of the Bit Map headers
354 // is equal to the number of Objects that the current Block can
355 // store, then there is definitely no space for another single
356 // object, so just return false.
357 _Counter_type __diff
= __detail::__num_bitmaps(__bp
);
359 if (*(reinterpret_cast<size_t*>
360 (__bp
.first
) - (__diff
+ 1)) == __detail::__num_blocks(__bp
))
363 size_t* __rover
= reinterpret_cast<size_t*>(__bp
.first
) - 1;
365 for (_Counter_type __i
= 0; __i
< __diff
; ++__i
)
367 _M_data_offset
= __i
;
370 _M_pbitmap
= __rover
;
379 _M_get() const throw()
380 { return _M_pbitmap
; }
383 _M_offset() const throw()
384 { return _M_data_offset
* std::size_t(bits_per_block
); }
387 /** @class _Bitmap_counter bitmap_allocator.h bitmap_allocator.h
389 * @brief The bitmap counter which acts as the bitmap
390 * manipulator, and manages the bit-manipulation functions and
391 * the searching and identification functions on the bit-map.
393 // _Tp should be a pointer type.
394 template<typename _Tp
>
395 class _Bitmap_counter
398 __detail::__mini_vector
<typename
std::pair
<_Tp
, _Tp
> > _BPVector
;
399 typedef typename
_BPVector::size_type _Index_type
;
403 std::size_t* _M_curr_bmap
;
404 std::size_t* _M_last_bmap_in_block
;
405 _Index_type _M_curr_index
;
408 // Use the 2nd parameter with care. Make sure that such an
409 // entry exists in the vector before passing that particular
410 // index to this ctor.
411 _Bitmap_counter(_BPVector
& Rvbp
, long __index
= -1) : _M_vbp(Rvbp
)
412 { this->_M_reset(__index
); }
415 _M_reset(long __index
= -1) throw()
420 _M_curr_index
= static_cast<_Index_type
>(-1);
424 _M_curr_index
= __index
;
425 _M_curr_bmap
= reinterpret_cast<std::size_t*>
426 (_M_vbp
[_M_curr_index
].first
) - 1;
428 _GLIBCXX_DEBUG_ASSERT(__index
<= (long)_M_vbp
.size() - 1);
430 _M_last_bmap_in_block
= _M_curr_bmap
431 - ((_M_vbp
[_M_curr_index
].second
432 - _M_vbp
[_M_curr_index
].first
+ 1)
433 / std::size_t(bits_per_block
) - 1);
436 // Dangerous Function! Use with extreme care. Pass to this
437 // function ONLY those values that are known to be correct,
438 // otherwise this will mess up big time.
440 _M_set_internal_bitmap(std::size_t* __new_internal_marker
) throw()
441 { _M_curr_bmap
= __new_internal_marker
; }
444 _M_finished() const throw()
445 { return(_M_curr_bmap
== 0); }
450 if (_M_curr_bmap
== _M_last_bmap_in_block
)
452 if (++_M_curr_index
== _M_vbp
.size())
455 this->_M_reset(_M_curr_index
);
463 _M_get() const throw()
464 { return _M_curr_bmap
; }
467 _M_base() const throw()
468 { return _M_vbp
[_M_curr_index
].first
; }
471 _M_offset() const throw()
473 return std::size_t(bits_per_block
)
474 * ((reinterpret_cast<std::size_t*>(this->_M_base())
475 - _M_curr_bmap
) - 1);
479 _M_where() const throw()
480 { return _M_curr_index
; }
483 /** @brief Mark a memory address as allocated by re-setting the
484 * corresponding bit in the bit-map.
487 __bit_allocate(std::size_t* __pbmap
, std::size_t __pos
) throw()
489 std::size_t __mask
= 1 << __pos
;
494 /** @brief Mark a memory address as free by setting the
495 * corresponding bit in the bit-map.
498 __bit_free(std::size_t* __pbmap
, std::size_t __pos
) throw()
500 std::size_t __mask
= 1 << __pos
;
503 } // namespace __detail
505 /** @brief Generic Version of the bsf instruction.
508 _Bit_scan_forward(std::size_t __num
)
509 { return static_cast<std::size_t>(__builtin_ctzl(__num
)); }
511 /** @class free_list bitmap_allocator.h bitmap_allocator.h
513 * @brief The free list class for managing chunks of memory to be
514 * given to and returned by the bitmap_allocator.
519 typedef std::size_t* value_type
;
520 typedef __detail::__mini_vector
<value_type
> vector_type
;
521 typedef vector_type::iterator iterator
;
522 typedef __mutex __mutex_type
;
525 struct _LT_pointer_compare
528 operator()(const std::size_t* __pui
,
529 const std::size_t __cui
) const throw()
530 { return *__pui
< __cui
; }
533 #if defined __GTHREADS
537 static __mutex_type _S_mutex
;
545 static vector_type _S_free_list
;
549 /** @brief Performs validation of memory based on their size.
551 * @param __addr The pointer to the memory block to be
554 * Validates the memory block passed to this function and
555 * appropriately performs the action of managing the free list of
556 * blocks by adding this block to the free list or deleting this
557 * or larger blocks from the free list.
560 _M_validate(std::size_t* __addr
) throw()
562 vector_type
& __free_list
= _M_get_free_list();
563 const vector_type::size_type __max_size
= 64;
564 if (__free_list
.size() >= __max_size
)
566 // Ok, the threshold value has been reached. We determine
567 // which block to remove from the list of free blocks.
568 if (*__addr
>= *__free_list
.back())
570 // Ok, the new block is greater than or equal to the
571 // last block in the list of free blocks. We just free
573 ::operator delete(static_cast<void*>(__addr
));
578 // Deallocate the last block in the list of free lists,
579 // and insert the new one in its correct position.
580 ::operator delete(static_cast<void*>(__free_list
.back()));
581 __free_list
.pop_back();
585 // Just add the block to the list of free lists unconditionally.
586 iterator __temp
= __detail::__lower_bound
587 (__free_list
.begin(), __free_list
.end(),
588 *__addr
, _LT_pointer_compare());
590 // We may insert the new free list before _temp;
591 __free_list
.insert(__temp
, __addr
);
594 /** @brief Decides whether the wastage of memory is acceptable for
595 * the current memory request and returns accordingly.
597 * @param __block_size The size of the block available in the free
600 * @param __required_size The required size of the memory block.
602 * @return true if the wastage incurred is acceptable, else returns
606 _M_should_i_give(std::size_t __block_size
,
607 std::size_t __required_size
) throw()
609 const std::size_t __max_wastage_percentage
= 36;
610 if (__block_size
>= __required_size
&&
611 (((__block_size
- __required_size
) * 100 / __block_size
)
612 < __max_wastage_percentage
))
619 /** @brief This function returns the block of memory to the
620 * internal free list.
622 * @param __addr The pointer to the memory block that was given
623 * by a call to the _M_get function.
626 _M_insert(std::size_t* __addr
) throw()
628 #if defined __GTHREADS
629 __scoped_lock
__bfl_lock(_M_get_mutex());
631 // Call _M_validate to decide what should be done with
632 // this particular free list.
633 this->_M_validate(reinterpret_cast<std::size_t*>(__addr
) - 1);
634 // See discussion as to why this is 1!
637 /** @brief This function gets a block of memory of the specified
638 * size from the free list.
640 * @param __sz The size in bytes of the memory required.
642 * @return A pointer to the new memory block of size at least
643 * equal to that requested.
646 _M_get(std::size_t __sz
) _GLIBCXX_THROW(std::bad_alloc
);
648 /** @brief This function just clears the internal Free List, and
649 * gives back all the memory to the OS.
656 // Forward declare the class.
657 template<typename _Tp
>
658 class bitmap_allocator
;
660 // Specialize for void:
662 class bitmap_allocator
<void>
665 typedef void* pointer
;
666 typedef const void* const_pointer
;
668 // Reference-to-void members are impossible.
669 typedef void value_type
;
670 template<typename _Tp1
>
673 typedef bitmap_allocator
<_Tp1
> other
;
678 * @brief Bitmap Allocator, primary template.
679 * @ingroup allocators
681 template<typename _Tp
>
682 class bitmap_allocator
: private free_list
685 typedef std::size_t size_type
;
686 typedef std::ptrdiff_t difference_type
;
687 typedef _Tp
* pointer
;
688 typedef const _Tp
* const_pointer
;
689 typedef _Tp
& reference
;
690 typedef const _Tp
& const_reference
;
691 typedef _Tp value_type
;
692 typedef free_list::__mutex_type __mutex_type
;
694 template<typename _Tp1
>
697 typedef bitmap_allocator
<_Tp1
> other
;
700 #if __cplusplus >= 201103L
701 // _GLIBCXX_RESOLVE_LIB_DEFECTS
702 // 2103. propagate_on_container_move_assignment
703 typedef std::true_type propagate_on_container_move_assignment
;
707 template<std::size_t _BSize
, std::size_t _AlignSize
>
712 modulus
= _BSize
% _AlignSize
,
713 value
= _BSize
+ (modulus
? _AlignSize
- (modulus
) : 0)
719 char __M_unused
[aligned_size
<sizeof(value_type
),
720 _BALLOC_ALIGN_BYTES
>::value
];
724 typedef typename
std::pair
<_Alloc_block
*, _Alloc_block
*> _Block_pair
;
726 typedef typename
__detail::__mini_vector
<_Block_pair
> _BPVector
;
727 typedef typename
_BPVector::iterator _BPiter
;
729 template<typename _Predicate
>
731 _S_find(_Predicate __p
)
733 _BPiter __first
= _S_mem_blocks
.begin();
734 while (__first
!= _S_mem_blocks
.end() && !__p(*__first
))
739 #if defined _GLIBCXX_DEBUG
740 // Complexity: O(lg(N)). Where, N is the number of block of size
741 // sizeof(value_type).
743 _S_check_for_free_blocks() throw()
745 typedef typename
__detail::_Ffit_finder
<_Alloc_block
*> _FFF
;
746 _BPiter __bpi
= _S_find(_FFF());
748 _GLIBCXX_DEBUG_ASSERT(__bpi
== _S_mem_blocks
.end());
752 /** @brief Responsible for exponentially growing the internal
755 * @throw std::bad_alloc. If memory cannot be allocated.
757 * Complexity: O(1), but internally depends upon the
758 * complexity of the function free_list::_M_get. The part where
759 * the bitmap headers are written has complexity: O(X),where X
760 * is the number of blocks of size sizeof(value_type) within
761 * the newly acquired block. Having a tight bound.
764 _S_refill_pool() _GLIBCXX_THROW(std::bad_alloc
)
767 #if defined _GLIBCXX_DEBUG
768 _S_check_for_free_blocks();
771 const size_t __num_bitmaps
= (_S_block_size
772 / size_t(__detail::bits_per_block
));
773 const size_t __size_to_allocate
= sizeof(size_t)
774 + _S_block_size
* sizeof(_Alloc_block
)
775 + __num_bitmaps
* sizeof(size_t);
778 reinterpret_cast<size_t*>(this->_M_get(__size_to_allocate
));
782 // The Header information goes at the Beginning of the Block.
784 std::make_pair(reinterpret_cast<_Alloc_block
*>
785 (__temp
+ __num_bitmaps
),
786 reinterpret_cast<_Alloc_block
*>
787 (__temp
+ __num_bitmaps
)
788 + _S_block_size
- 1);
790 // Fill the Vector with this information.
791 _S_mem_blocks
.push_back(__bp
);
793 for (size_t __i
= 0; __i
< __num_bitmaps
; ++__i
)
794 __temp
[__i
] = ~static_cast<size_t>(0); // 1 Indicates all Free.
799 static _BPVector _S_mem_blocks
;
800 static std::size_t _S_block_size
;
801 static __detail::_Bitmap_counter
<_Alloc_block
*> _S_last_request
;
802 static typename
_BPVector::size_type _S_last_dealloc_index
;
803 #if defined __GTHREADS
804 static __mutex_type _S_mut
;
809 /** @brief Allocates memory for a single object of size
812 * @throw std::bad_alloc. If memory cannot be allocated.
814 * Complexity: Worst case complexity is O(N), but that
815 * is hardly ever hit. If and when this particular case is
816 * encountered, the next few cases are guaranteed to have a
817 * worst case complexity of O(1)! That's why this function
818 * performs very well on average. You can consider this
819 * function to have a complexity referred to commonly as:
820 * Amortized Constant time.
823 _M_allocate_single_object() _GLIBCXX_THROW(std::bad_alloc
)
826 #if defined __GTHREADS
827 __scoped_lock
__bit_lock(_S_mut
);
830 // The algorithm is something like this: The last_request
831 // variable points to the last accessed Bit Map. When such a
832 // condition occurs, we try to find a free block in the
833 // current bitmap, or succeeding bitmaps until the last bitmap
834 // is reached. If no free block turns up, we resort to First
837 // WARNING: Do not re-order the condition in the while
838 // statement below, because it relies on C++'s short-circuit
839 // evaluation. The return from _S_last_request->_M_get() will
840 // NOT be dereference able if _S_last_request->_M_finished()
841 // returns true. This would inevitably lead to a NULL pointer
842 // dereference if tinkered with.
843 while (_S_last_request
._M_finished() == false
844 && (*(_S_last_request
._M_get()) == 0))
845 _S_last_request
.operator++();
847 if (__builtin_expect(_S_last_request
._M_finished() == true, false))
849 // Fall Back to First Fit algorithm.
850 typedef typename
__detail::_Ffit_finder
<_Alloc_block
*> _FFF
;
852 _BPiter __bpi
= _S_find(__detail::_Functor_Ref
<_FFF
>(__fff
));
854 if (__bpi
!= _S_mem_blocks
.end())
856 // Search was successful. Ok, now mark the first bit from
857 // the right as 0, meaning Allocated. This bit is obtained
858 // by calling _M_get() on __fff.
859 size_t __nz_bit
= _Bit_scan_forward(*__fff
._M_get());
860 __detail::__bit_allocate(__fff
._M_get(), __nz_bit
);
862 _S_last_request
._M_reset(__bpi
- _S_mem_blocks
.begin());
864 // Now, get the address of the bit we marked as allocated.
865 pointer __ret
= reinterpret_cast<pointer
>
866 (__bpi
->first
+ __fff
._M_offset() + __nz_bit
);
867 size_t* __puse_count
=
868 reinterpret_cast<size_t*>
869 (__bpi
->first
) - (__detail::__num_bitmaps(*__bpi
) + 1);
876 // Search was unsuccessful. We Add more memory to the
877 // pool by calling _S_refill_pool().
880 // _M_Reset the _S_last_request structure to the first
881 // free block's bit map.
882 _S_last_request
._M_reset(_S_mem_blocks
.size() - 1);
884 // Now, mark that bit as allocated.
888 // _S_last_request holds a pointer to a valid bit map, that
889 // points to a free block in memory.
890 size_t __nz_bit
= _Bit_scan_forward(*_S_last_request
._M_get());
891 __detail::__bit_allocate(_S_last_request
._M_get(), __nz_bit
);
893 pointer __ret
= reinterpret_cast<pointer
>
894 (_S_last_request
._M_base() + _S_last_request
._M_offset() + __nz_bit
);
896 size_t* __puse_count
= reinterpret_cast<size_t*>
897 (_S_mem_blocks
[_S_last_request
._M_where()].first
)
899 __num_bitmaps(_S_mem_blocks
[_S_last_request
._M_where()]) + 1);
905 /** @brief Deallocates memory that belongs to a single object of
908 * Complexity: O(lg(N)), but the worst case is not hit
909 * often! This is because containers usually deallocate memory
910 * close to each other and this case is handled in O(1) time by
911 * the deallocate function.
914 _M_deallocate_single_object(pointer __p
) throw()
917 #if defined __GTHREADS
918 __scoped_lock
__bit_lock(_S_mut
);
920 _Alloc_block
* __real_p
= reinterpret_cast<_Alloc_block
*>(__p
);
922 typedef typename
_BPVector::iterator _Iterator
;
923 typedef typename
_BPVector::difference_type _Difference_type
;
925 _Difference_type __diff
;
928 _GLIBCXX_DEBUG_ASSERT(_S_last_dealloc_index
>= 0);
930 __detail::_Inclusive_between
<_Alloc_block
*> __ibt(__real_p
);
931 if (__ibt(_S_mem_blocks
[_S_last_dealloc_index
]))
933 _GLIBCXX_DEBUG_ASSERT(_S_last_dealloc_index
934 <= _S_mem_blocks
.size() - 1);
936 // Initial Assumption was correct!
937 __diff
= _S_last_dealloc_index
;
938 __displacement
= __real_p
- _S_mem_blocks
[__diff
].first
;
942 _Iterator _iter
= _S_find(__ibt
);
944 _GLIBCXX_DEBUG_ASSERT(_iter
!= _S_mem_blocks
.end());
946 __diff
= _iter
- _S_mem_blocks
.begin();
947 __displacement
= __real_p
- _S_mem_blocks
[__diff
].first
;
948 _S_last_dealloc_index
= __diff
;
951 // Get the position of the iterator that has been found.
952 const size_t __rotate
= (__displacement
953 % size_t(__detail::bits_per_block
));
955 reinterpret_cast<size_t*>
956 (_S_mem_blocks
[__diff
].first
) - 1;
957 __bitmapC
-= (__displacement
/ size_t(__detail::bits_per_block
));
959 __detail::__bit_free(__bitmapC
, __rotate
);
960 size_t* __puse_count
= reinterpret_cast<size_t*>
961 (_S_mem_blocks
[__diff
].first
)
962 - (__detail::__num_bitmaps(_S_mem_blocks
[__diff
]) + 1);
964 _GLIBCXX_DEBUG_ASSERT(*__puse_count
!= 0);
968 if (__builtin_expect(*__puse_count
== 0, false))
972 // We can safely remove this block.
973 // _Block_pair __bp = _S_mem_blocks[__diff];
974 this->_M_insert(__puse_count
);
975 _S_mem_blocks
.erase(_S_mem_blocks
.begin() + __diff
);
977 // Reset the _S_last_request variable to reflect the
978 // erased block. We do this to protect future requests
979 // after the last block has been removed from a particular
980 // memory Chunk, which in turn has been returned to the
981 // free list, and hence had been erased from the vector,
982 // so the size of the vector gets reduced by 1.
983 if ((_Difference_type
)_S_last_request
._M_where() >= __diff
--)
984 _S_last_request
._M_reset(__diff
);
986 // If the Index into the vector of the region of memory
987 // that might hold the next address that will be passed to
988 // deallocated may have been invalidated due to the above
989 // erase procedure being called on the vector, hence we
990 // try to restore this invariant too.
991 if (_S_last_dealloc_index
>= _S_mem_blocks
.size())
993 _S_last_dealloc_index
=(__diff
!= -1 ? __diff
: 0);
994 _GLIBCXX_DEBUG_ASSERT(_S_last_dealloc_index
>= 0);
1000 bitmap_allocator() _GLIBCXX_USE_NOEXCEPT
1003 bitmap_allocator(const bitmap_allocator
&) _GLIBCXX_USE_NOEXCEPT
1006 template<typename _Tp1
>
1007 bitmap_allocator(const bitmap_allocator
<_Tp1
>&) _GLIBCXX_USE_NOEXCEPT
1010 ~bitmap_allocator() _GLIBCXX_USE_NOEXCEPT
1013 _GLIBCXX_NODISCARD pointer
1014 allocate(size_type __n
)
1016 if (__n
> this->max_size())
1017 std::__throw_bad_alloc();
1019 #if __cpp_aligned_new
1020 if (alignof(value_type
) > __STDCPP_DEFAULT_NEW_ALIGNMENT__
)
1022 const size_type __b
= __n
* sizeof(value_type
);
1023 std::align_val_t __al
= std::align_val_t(alignof(value_type
));
1024 return static_cast<pointer
>(::operator new(__b
, __al
));
1028 if (__builtin_expect(__n
== 1, true))
1029 return this->_M_allocate_single_object();
1032 const size_type __b
= __n
* sizeof(value_type
);
1033 return reinterpret_cast<pointer
>(::operator new(__b
));
1037 _GLIBCXX_NODISCARD pointer
1038 allocate(size_type __n
, typename bitmap_allocator
<void>::const_pointer
)
1039 { return allocate(__n
); }
1042 deallocate(pointer __p
, size_type __n
) throw()
1044 if (__builtin_expect(__p
!= 0, true))
1046 #if __cpp_aligned_new
1047 // Types with extended alignment are handled by operator delete.
1048 if (alignof(value_type
) > __STDCPP_DEFAULT_NEW_ALIGNMENT__
)
1050 ::operator delete(__p
, std::align_val_t(alignof(value_type
)));
1055 if (__builtin_expect(__n
== 1, true))
1056 this->_M_deallocate_single_object(__p
);
1058 ::operator delete(__p
);
1063 address(reference __r
) const _GLIBCXX_NOEXCEPT
1064 { return std::__addressof(__r
); }
1067 address(const_reference __r
) const _GLIBCXX_NOEXCEPT
1068 { return std::__addressof(__r
); }
1071 max_size() const _GLIBCXX_USE_NOEXCEPT
1072 { return size_type(-1) / sizeof(value_type
); }
1074 #if __cplusplus >= 201103L
1075 template<typename _Up
, typename
... _Args
>
1077 construct(_Up
* __p
, _Args
&&... __args
)
1078 { ::new((void *)__p
) _Up(std::forward
<_Args
>(__args
)...); }
1080 template<typename _Up
>
1086 construct(pointer __p
, const_reference __data
)
1087 { ::new((void *)__p
) value_type(__data
); }
1090 destroy(pointer __p
)
1091 { __p
->~value_type(); }
1095 template<typename _Tp1
, typename _Tp2
>
1097 operator==(const bitmap_allocator
<_Tp1
>&,
1098 const bitmap_allocator
<_Tp2
>&) throw()
1101 template<typename _Tp1
, typename _Tp2
>
1103 operator!=(const bitmap_allocator
<_Tp1
>&,
1104 const bitmap_allocator
<_Tp2
>&) throw()
1107 // Static member definitions.
1108 template<typename _Tp
>
1109 typename bitmap_allocator
<_Tp
>::_BPVector
1110 bitmap_allocator
<_Tp
>::_S_mem_blocks
;
1112 template<typename _Tp
>
1113 std::size_t bitmap_allocator
<_Tp
>::_S_block_size
1114 = 2 * std::size_t(__detail::bits_per_block
);
1116 template<typename _Tp
>
1117 typename bitmap_allocator
<_Tp
>::_BPVector::size_type
1118 bitmap_allocator
<_Tp
>::_S_last_dealloc_index
= 0;
1120 template<typename _Tp
>
1121 __detail::_Bitmap_counter
1122 <typename bitmap_allocator
<_Tp
>::_Alloc_block
*>
1123 bitmap_allocator
<_Tp
>::_S_last_request(_S_mem_blocks
);
1125 #if defined __GTHREADS
1126 template<typename _Tp
>
1127 typename bitmap_allocator
<_Tp
>::__mutex_type
1128 bitmap_allocator
<_Tp
>::_S_mut
;
1131 _GLIBCXX_END_NAMESPACE_VERSION
1132 } // namespace __gnu_cxx