diff options
Diffstat (limited to 'gcc-4.4.3/libstdc++-v3/include/ext/pool_allocator.h')
| -rw-r--r-- | gcc-4.4.3/libstdc++-v3/include/ext/pool_allocator.h | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/gcc-4.4.3/libstdc++-v3/include/ext/pool_allocator.h b/gcc-4.4.3/libstdc++-v3/include/ext/pool_allocator.h new file mode 100644 index 000000000..87d145d71 --- /dev/null +++ b/gcc-4.4.3/libstdc++-v3/include/ext/pool_allocator.h @@ -0,0 +1,263 @@ +// Allocators -*- C++ -*- + +// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 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/>. + +/* + * Copyright (c) 1996-1997 + * Silicon Graphics Computer Systems, Inc. + * + * Permission to use, copy, modify, distribute and sell this software + * and its documentation for any purpose is hereby granted without fee, + * provided that the above copyright notice appear in all copies and + * that both that copyright notice and this permission notice appear + * in supporting documentation. Silicon Graphics makes no + * representations about the suitability of this software for any + * purpose. It is provided "as is" without express or implied warranty. + */ + +/** @file ext/pool_allocator.h + * This file is a GNU extension to the Standard C++ Library. + */ + +#ifndef _POOL_ALLOCATOR_H +#define _POOL_ALLOCATOR_H 1 + +#include <bits/c++config.h> +#include <cstdlib> +#include <new> +#include <bits/functexcept.h> +#include <ext/atomicity.h> +#include <ext/concurrence.h> +#include <bits/move.h> + +_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) + + using std::size_t; + using std::ptrdiff_t; + + /** + * @brief Base class for __pool_alloc. + * + * Uses various allocators to fulfill underlying requests (and makes as + * few requests as possible when in default high-speed pool mode). + * + * Important implementation properties: + * 0. If globally mandated, then allocate objects from new + * 1. If the clients request an object of size > _S_max_bytes, the resulting + * object will be obtained directly from new + * 2. In all other cases, we allocate an object of size exactly + * _S_round_up(requested_size). Thus the client has enough size + * information that we can return the object to the proper free list + * without permanently losing part of the object. + */ + class __pool_alloc_base + { + protected: + + enum { _S_align = 8 }; + enum { _S_max_bytes = 128 }; + enum { _S_free_list_size = (size_t)_S_max_bytes / (size_t)_S_align }; + + union _Obj + { + union _Obj* _M_free_list_link; + char _M_client_data[1]; // The client sees this. + }; + + static _Obj* volatile _S_free_list[_S_free_list_size]; + + // Chunk allocation state. + static char* _S_start_free; + static char* _S_end_free; + static size_t _S_heap_size; + + size_t + _M_round_up(size_t __bytes) + { return ((__bytes + (size_t)_S_align - 1) & ~((size_t)_S_align - 1)); } + + _Obj* volatile* + _M_get_free_list(size_t __bytes); + + __mutex& + _M_get_mutex(); + + // Returns an object of size __n, and optionally adds to size __n + // free list. + void* + _M_refill(size_t __n); + + // Allocates a chunk for nobjs of size size. nobjs may be reduced + // if it is inconvenient to allocate the requested number. + char* + _M_allocate_chunk(size_t __n, int& __nobjs); + }; + + + /** + * @brief Allocator using a memory pool with a single lock. + * @ingroup allocators + */ + template<typename _Tp> + class __pool_alloc : private __pool_alloc_base + { + private: + static _Atomic_word _S_force_new; + + 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 __pool_alloc<_Tp1> other; }; + + __pool_alloc() throw() { } + + __pool_alloc(const __pool_alloc&) throw() { } + + template<typename _Tp1> + __pool_alloc(const __pool_alloc<_Tp1>&) throw() { } + + ~__pool_alloc() throw() { } + + pointer + address(reference __x) const { return &__x; } + + const_pointer + address(const_reference __x) const { return &__x; } + + size_type + max_size() const throw() + { return size_t(-1) / sizeof(_Tp); } + + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 402. wrong new expression in [some_] allocator::construct + void + construct(pointer __p, const _Tp& __val) + { ::new((void *)__p) _Tp(__val); } + +#ifdef __GXX_EXPERIMENTAL_CXX0X__ + template<typename... _Args> + void + construct(pointer __p, _Args&&... __args) + { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); } +#endif + + void + destroy(pointer __p) { __p->~_Tp(); } + + pointer + allocate(size_type __n, const void* = 0); + + void + deallocate(pointer __p, size_type __n); + }; + + template<typename _Tp> + inline bool + operator==(const __pool_alloc<_Tp>&, const __pool_alloc<_Tp>&) + { return true; } + + template<typename _Tp> + inline bool + operator!=(const __pool_alloc<_Tp>&, const __pool_alloc<_Tp>&) + { return false; } + + template<typename _Tp> + _Atomic_word + __pool_alloc<_Tp>::_S_force_new; + + template<typename _Tp> + _Tp* + __pool_alloc<_Tp>::allocate(size_type __n, const void*) + { + pointer __ret = 0; + if (__builtin_expect(__n != 0, true)) + { + if (__builtin_expect(__n > this->max_size(), false)) + std::__throw_bad_alloc(); + + // If there is a race through here, assume answer from getenv + // will resolve in same direction. Inspired by techniques + // to efficiently support threading found in basic_string.h. + if (_S_force_new == 0) + { + if (std::getenv("GLIBCXX_FORCE_NEW")) + __atomic_add_dispatch(&_S_force_new, 1); + else + __atomic_add_dispatch(&_S_force_new, -1); + } + + const size_t __bytes = __n * sizeof(_Tp); + if (__bytes > size_t(_S_max_bytes) || _S_force_new > 0) + __ret = static_cast<_Tp*>(::operator new(__bytes)); + else + { + _Obj* volatile* __free_list = _M_get_free_list(__bytes); + + __scoped_lock sentry(_M_get_mutex()); + _Obj* __restrict__ __result = *__free_list; + if (__builtin_expect(__result == 0, 0)) + __ret = static_cast<_Tp*>(_M_refill(_M_round_up(__bytes))); + else + { + *__free_list = __result->_M_free_list_link; + __ret = reinterpret_cast<_Tp*>(__result); + } + if (__builtin_expect(__ret == 0, 0)) + std::__throw_bad_alloc(); + } + } + return __ret; + } + + template<typename _Tp> + void + __pool_alloc<_Tp>::deallocate(pointer __p, size_type __n) + { + if (__builtin_expect(__n != 0 && __p != 0, true)) + { + const size_t __bytes = __n * sizeof(_Tp); + if (__bytes > static_cast<size_t>(_S_max_bytes) || _S_force_new > 0) + ::operator delete(__p); + else + { + _Obj* volatile* __free_list = _M_get_free_list(__bytes); + _Obj* __q = reinterpret_cast<_Obj*>(__p); + + __scoped_lock sentry(_M_get_mutex()); + __q ->_M_free_list_link = *__free_list; + *__free_list = __q; + } + } + } + +_GLIBCXX_END_NAMESPACE + +#endif |