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// Allocator details.
// Copyright (C) 2004, 2005, 2006, 2009 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
//
// ISO C++ 14882:
//
#include <bits/c++config.h>
#include <cstdlib>
#include <ext/pool_allocator.h>
namespace
{
__gnu_cxx::__mutex&
get_palloc_mutex()
{
static __gnu_cxx::__mutex palloc_mutex;
return palloc_mutex;
}
} // anonymous namespace
_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
// Definitions for __pool_alloc_base.
__pool_alloc_base::_Obj* volatile*
__pool_alloc_base::_M_get_free_list(size_t __bytes)
{
size_t __i = ((__bytes + (size_t)_S_align - 1) / (size_t)_S_align - 1);
return _S_free_list + __i;
}
__mutex&
__pool_alloc_base::_M_get_mutex()
{ return get_palloc_mutex(); }
// Allocate memory in large chunks in order to avoid fragmenting the
// heap too much. Assume that __n is properly aligned. We hold the
// allocation lock.
char*
__pool_alloc_base::_M_allocate_chunk(size_t __n, int& __nobjs)
{
char* __result;
size_t __total_bytes = __n * __nobjs;
size_t __bytes_left = _S_end_free - _S_start_free;
if (__bytes_left >= __total_bytes)
{
__result = _S_start_free;
_S_start_free += __total_bytes;
return __result ;
}
else if (__bytes_left >= __n)
{
__nobjs = (int)(__bytes_left / __n);
__total_bytes = __n * __nobjs;
__result = _S_start_free;
_S_start_free += __total_bytes;
return __result;
}
else
{
// Try to make use of the left-over piece.
if (__bytes_left > 0)
{
_Obj* volatile* __free_list = _M_get_free_list(__bytes_left);
((_Obj*)(void*)_S_start_free)->_M_free_list_link = *__free_list;
*__free_list = (_Obj*)(void*)_S_start_free;
}
size_t __bytes_to_get = (2 * __total_bytes
+ _M_round_up(_S_heap_size >> 4));
try
{
_S_start_free = static_cast<char*>(::operator new(__bytes_to_get));
}
catch (...)
{
// Try to make do with what we have. That can't hurt. We
// do not try smaller requests, since that tends to result
// in disaster on multi-process machines.
size_t __i = __n;
for (; __i <= (size_t) _S_max_bytes; __i += (size_t) _S_align)
{
_Obj* volatile* __free_list = _M_get_free_list(__i);
_Obj* __p = *__free_list;
if (__p != 0)
{
*__free_list = __p->_M_free_list_link;
_S_start_free = (char*)__p;
_S_end_free = _S_start_free + __i;
return _M_allocate_chunk(__n, __nobjs);
// Any leftover piece will eventually make it to the
// right free list.
}
}
// What we have wasn't enough. Rethrow.
_S_start_free = _S_end_free = 0; // We have no chunk.
__throw_exception_again;
}
_S_heap_size += __bytes_to_get;
_S_end_free = _S_start_free + __bytes_to_get;
return _M_allocate_chunk(__n, __nobjs);
}
}
// Returns an object of size __n, and optionally adds to "size
// __n"'s free list. We assume that __n is properly aligned. We
// hold the allocation lock.
void*
__pool_alloc_base::_M_refill(size_t __n)
{
int __nobjs = 20;
char* __chunk = _M_allocate_chunk(__n, __nobjs);
_Obj* volatile* __free_list;
_Obj* __result;
_Obj* __current_obj;
_Obj* __next_obj;
if (__nobjs == 1)
return __chunk;
__free_list = _M_get_free_list(__n);
// Build free list in chunk.
__result = (_Obj*)(void*)__chunk;
*__free_list = __next_obj = (_Obj*)(void*)(__chunk + __n);
for (int __i = 1; ; __i++)
{
__current_obj = __next_obj;
__next_obj = (_Obj*)(void*)((char*)__next_obj + __n);
if (__nobjs - 1 == __i)
{
__current_obj->_M_free_list_link = 0;
break;
}
else
__current_obj->_M_free_list_link = __next_obj;
}
return __result;
}
__pool_alloc_base::_Obj* volatile __pool_alloc_base::_S_free_list[_S_free_list_size];
char* __pool_alloc_base::_S_start_free = 0;
char* __pool_alloc_base::_S_end_free = 0;
size_t __pool_alloc_base::_S_heap_size = 0;
// Instantiations.
template class __pool_alloc<char>;
template class __pool_alloc<wchar_t>;
_GLIBCXX_END_NAMESPACE
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