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Hello,
This is a patch for the bitmap allocator. The issues touched
are:
[This is actually a patch file, not a normal file to be copy-pasted, as
I wrongly sent earlier.]
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
Attachment:
ChangeLog
Description: Text document
*** bitmap_allocator.h 2004-03-24 23:57:43.000000000 +0530
--- /home/dhruv/projects/mystl/v3.4/bitmap_allocator.h 2004-05-07 21:56:42.000000000 +0530
***************
*** 33,79 ****
#define _BITMAP_ALLOCATOR_H 1
#include <cstddef>
! //For std::size_t, and ptrdiff_t.
#include <utility>
//For std::pair.
- #include <algorithm>
- //std::find_if, and std::lower_bound.
#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.
! #include <cassert>
! #define NDEBUG
! //#define CHECK_FOR_ERRORS
! //#define __CPU_HAS_BACKWARD_BRANCH_PREDICTION
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)
{
--- 33,82 ----
#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)
{
*************** namespace __gnu_cxx
*** 85,108 ****
#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)
! { this->_M_lock(); }
! void _M_lock()
{
if (__threads_enabled)
{
--- 88,115 ----
#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)
{
*************** namespace __gnu_cxx
*** 110,116 ****
__gthread_mutex_lock(_M_pmt->_M_get());
}
}
! void _M_unlock()
{
if (__threads_enabled)
{
--- 117,125 ----
__gthread_mutex_lock(_M_pmt->_M_get());
}
}
!
! void
! _M_unlock()
{
if (__threads_enabled)
{
*************** namespace __gnu_cxx
*** 121,356 ****
}
}
}
! ~_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 _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;
}
! //T 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); }
! };
- //T should be a pointer type, and A 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);
!
! 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; }
! };
! //T 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 = (_Index_type)-1;
! return;
! }
! _M_curr_index = __index;
! _M_curr_bmap = reinterpret_cast<unsigned int*>(_M_vbp[_M_curr_index].first) - 1;
! 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);
}
};
--- 130,484 ----
}
}
}
! ~_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);
}
};
*************** namespace __gnu_cxx
*** 359,417 ****
_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*> _S_free_list;
! typedef std::vector<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 = std::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;
--- 487,562 ----
_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;
*************** namespace __gnu_cxx
*** 420,466 ****
public:
typedef _BA_free_list_store _BFL_type;
! static inline void _S_insert_free_list(unsigned int *__addr) throw()
{
#if defined __GTHREADS
! _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
! _Lock __bfl_lock(&_S_bfl_mutex);
#endif
! _FLIter __temp = std::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
! _Lock __bfl_lock(&_S_bfl_mutex);
#endif
_FLIter __iter = _S_free_list.begin();
while (__iter != _S_free_list.end())
--- 565,620 ----
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())
*************** namespace __gnu_cxx
*** 476,858 ****
#if defined __GTHREADS
_Mutex _BA_free_list_store::_S_bfl_mutex;
#endif
! std::vector<unsigned int*> _BA_free_list_store::_S_free_list;
!
! 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;
! 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<pointer, pointer> _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 CHECK_FOR_ERRORS
! //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<pointer, _BPVec_allocator_type> _FFF;
! _FFF __fff;
! typedef typename _BPVector::iterator _BPiter;
! _BPiter __bpi = std::find_if(_S_mem_blocks.begin(), _S_mem_blocks.end(),
! __gnu_cxx::__aux_balloc::_Functor_Ref<_FFF>(__fff));
! 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 CHECK_FOR_ERRORS
! _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(value_type) + __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<pointer>(__temp + __num_bit_maps),
! reinterpret_cast<pointer>(__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<pointer, _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
! _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<pointer, _BPVec_allocator_type> _FFF;
! _FFF __fff;
! typedef typename _BPVector::iterator _BPiter;
! _BPiter __bpi = std::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 = __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 = _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
! _Lock __bit_lock(&_S_mut);
#endif
! typedef typename _BPVector::iterator _Iterator;
! typedef typename _BPVector::difference_type _Difference_type;
! _Difference_type __diff;
! int __displacement;
! assert(_S_last_dealloc_index >= 0);
! if (__gnu_cxx::__aux_balloc::_Inclusive_between<pointer>(__p)(_S_mem_blocks[_S_last_dealloc_index]))
! {
! assert(_S_last_dealloc_index <= _S_mem_blocks.size() - 1);
! //Initial Assumption was correct!
! __diff = _S_last_dealloc_index;
! __displacement = __p - _S_mem_blocks[__diff].first;
! }
! else
! {
! _Iterator _iter = (std::find_if(_S_mem_blocks.begin(), _S_mem_blocks.end(),
! __gnu_cxx::__aux_balloc::_Inclusive_between<pointer>(__p)));
! assert(_iter != _S_mem_blocks.end());
!
! __diff = _iter - _S_mem_blocks.begin();
! __displacement = __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);
! 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);
! // assert(__diff >= 0);
! }
!
! //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);
! 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)));
! }
! //Complexity: Worst case complexity is O(N) where N is the number of
! //blocks of size sizeof(value_type) within the free lists that the
! //allocator holds. However, this worst case is hit only when the
! //user supplies a bogus argument to hint. If the hint argument is
! //sensible, then the complexity drops to O(lg(N)), and in extreme
! //cases, even drops to as low as O(1). So, if the user supplied
! //argument is good, then this function performs very well.
! 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(void) 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>::pointer, 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;
! }
}
--- 630,1106 ----
#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;
! }
}
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