diff options
Diffstat (limited to 'libstdc++-v3/src/pool_allocator.cc')
| -rw-r--r-- | libstdc++-v3/src/pool_allocator.cc | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/libstdc++-v3/src/pool_allocator.cc b/libstdc++-v3/src/pool_allocator.cc new file mode 100644 index 000000000..f94656b03 --- /dev/null +++ b/libstdc++-v3/src/pool_allocator.cc @@ -0,0 +1,177 @@ +// 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 + +namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) +{ +_GLIBCXX_BEGIN_NAMESPACE_VERSION + + // Definitions for __pool_alloc_base. + __pool_alloc_base::_Obj* volatile* + __pool_alloc_base::_M_get_free_list(size_t __bytes) throw () + { + 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() throw () + { 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(const std::bad_alloc&) + { + // 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_VERSION +} // namespace |