release/src-rt-6.x.4708/toolchains/hndtools-arm-linux-2.6.36-uclibc-4.5.3/arm-brcm-linux-uclibcgnueabi/include/c++/4.5.3/ext/pool_allocator.h

   1 // Allocators -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   4 // Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 /*
  27  * Copyright (c) 1996-1997
  28  * Silicon Graphics Computer Systems, Inc.
  29  *
  30  * Permission to use, copy, modify, distribute and sell this software
  31  * and its documentation for any purpose is hereby granted without fee,
  32  * provided that the above copyright notice appear in all copies and
  33  * that both that copyright notice and this permission notice appear
  34  * in supporting documentation.  Silicon Graphics makes no
  35  * representations about the suitability of this software for any
  36  * purpose.  It is provided "as is" without express or implied warranty.
  37  */
  38
  39 /** @file ext/pool_allocator.h
  40  *  This file is a GNU extension to the Standard C++ Library.
  41  */
  42
  43 #ifndef _POOL_ALLOCATOR_H
  44 #define _POOL_ALLOCATOR_H 1
  45
  46 #include <bits/c++config.h>
  47 #include <cstdlib>
  48 #include <new>
  49 #include <bits/functexcept.h>
  50 #include <ext/atomicity.h>
  51 #include <ext/concurrence.h>
  52 #include <bits/move.h>
  53
  54 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  55
  56   using std::size_t;
  57   using std::ptrdiff_t;
  58
  59   /**
  60    *  @brief  Base class for __pool_alloc.
  61    *
  62    *  Uses various allocators to fulfill underlying requests (and makes as
  63    *  few requests as possible when in default high-speed pool mode).
  64    *
  65    *  Important implementation properties:
  66    *  0. If globally mandated, then allocate objects from new
  67    *  1. If the clients request an object of size > _S_max_bytes, the resulting
  68    *     object will be obtained directly from new
  69    *  2. In all other cases, we allocate an object of size exactly
  70    *     _S_round_up(requested_size).  Thus the client has enough size
  71    *     information that we can return the object to the proper free list
  72    *     without permanently losing part of the object.
  73    */
  74     class __pool_alloc_base
  75     {
  76     protected:
  77
  78       enum { _S_align = 8 };
  79       enum { _S_max_bytes = 128 };
  80       enum { _S_free_list_size = (size_t)_S_max_bytes / (size_t)_S_align };
  81
  82       union _Obj
  83       {
  84         union _Obj* _M_free_list_link;
  85         char        _M_client_data[1];    // The client sees this.
  86       };
  87
  88       static _Obj* volatile         _S_free_list[_S_free_list_size];
  89
  90       // Chunk allocation state.
  91       static char*                  _S_start_free;
  92       static char*                  _S_end_free;
  93       static size_t                 _S_heap_size;
  94
  95       size_t
  96       _M_round_up(size_t __bytes)
  97       { return ((__bytes + (size_t)_S_align - 1) & ~((size_t)_S_align - 1)); }
  98
  99       _GLIBCXX_CONST _Obj* volatile*
 100       _M_get_free_list(size_t __bytes) throw ();
 101
 102       __mutex&
 103       _M_get_mutex() throw ();
 104
 105       // Returns an object of size __n, and optionally adds to size __n
 106       // free list.
 107       void*
 108       _M_refill(size_t __n);
 109
 110       // Allocates a chunk for nobjs of size size.  nobjs may be reduced
 111       // if it is inconvenient to allocate the requested number.
 112       char*
 113       _M_allocate_chunk(size_t __n, int& __nobjs);
 114     };
 115
 116
 117   /**
 118    * @brief  Allocator using a memory pool with a single lock.
 119    * @ingroup allocators
 120    */
 121   template<typename _Tp>
 122     class __pool_alloc : private __pool_alloc_base
 123     {
 124     private:
 125       static _Atomic_word           _S_force_new;
 126
 127     public:
 128       typedef size_t     size_type;
 129       typedef ptrdiff_t  difference_type;
 130       typedef _Tp*       pointer;
 131       typedef const _Tp* const_pointer;
 132       typedef _Tp&       reference;
 133       typedef const _Tp& const_reference;
 134       typedef _Tp        value_type;
 135
 136       template<typename _Tp1>
 137         struct rebind
 138         { typedef __pool_alloc<_Tp1> other; };
 139
 140       __pool_alloc() throw() { }
 141
 142       __pool_alloc(const __pool_alloc&) throw() { }
 143
 144       template<typename _Tp1>
 145         __pool_alloc(const __pool_alloc<_Tp1>&) throw() { }
 146
 147       ~__pool_alloc() throw() { }
 148
 149       pointer
 150       address(reference __x) const { return &__x; }
 151
 152       const_pointer
 153       address(const_reference __x) const { return &__x; }
 154
 155       size_type
 156       max_size() const throw()
 157       { return size_t(-1) / sizeof(_Tp); }
 158
 159       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 160       // 402. wrong new expression in [some_] allocator::construct
 161       void
 162       construct(pointer __p, const _Tp& __val)
 163       { ::new((void *)__p) _Tp(__val); }
 164
 165 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 166       template<typename... _Args>
 167         void
 168         construct(pointer __p, _Args&&... __args)
 169         { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); }
 170 #endif
 171
 172       void
 173       destroy(pointer __p) { __p->~_Tp(); }
 174
 175       pointer
 176       allocate(size_type __n, const void* = 0);
 177
 178       void
 179       deallocate(pointer __p, size_type __n);
 180     };
 181
 182   template<typename _Tp>
 183     inline bool
 184     operator==(const __pool_alloc<_Tp>&, const __pool_alloc<_Tp>&)
 185     { return true; }
 186
 187   template<typename _Tp>
 188     inline bool
 189     operator!=(const __pool_alloc<_Tp>&, const __pool_alloc<_Tp>&)
 190     { return false; }
 191
 192   template<typename _Tp>
 193     _Atomic_word
 194     __pool_alloc<_Tp>::_S_force_new;
 195
 196   template<typename _Tp>
 197     _Tp*
 198     __pool_alloc<_Tp>::allocate(size_type __n, const void*)
 199     {
 200       pointer __ret = 0;
 201       if (__builtin_expect(__n != 0, true))
 202         {
 203           if (__n > this->max_size())
 204             std::__throw_bad_alloc();
 205
 206           // If there is a race through here, assume answer from getenv
 207           // will resolve in same direction.  Inspired by techniques
 208           // to efficiently support threading found in basic_string.h.
 209           if (_S_force_new == 0)
 210             {
 211               if (std::getenv("GLIBCXX_FORCE_NEW"))
 212                 __atomic_add_dispatch(&_S_force_new, 1);
 213               else
 214                 __atomic_add_dispatch(&_S_force_new, -1);
 215             }
 216
 217           const size_t __bytes = __n * sizeof(_Tp);
 218           if (__bytes > size_t(_S_max_bytes) || _S_force_new > 0)
 219             __ret = static_cast<_Tp*>(::operator new(__bytes));
 220           else
 221             {
 222               _Obj* volatile* __free_list = _M_get_free_list(__bytes);
 223
 224               __scoped_lock sentry(_M_get_mutex());
 225               _Obj* __restrict__ __result = *__free_list;
 226               if (__builtin_expect(__result == 0, 0))
 227                 __ret = static_cast<_Tp*>(_M_refill(_M_round_up(__bytes)));
 228               else
 229                 {
 230                   *__free_list = __result->_M_free_list_link;
 231                   __ret = reinterpret_cast<_Tp*>(__result);
 232                 }
 233               if (__ret == 0)
 234                 std::__throw_bad_alloc();
 235             }
 236         }
 237       return __ret;
 238     }
 239
 240   template<typename _Tp>
 241     void
 242     __pool_alloc<_Tp>::deallocate(pointer __p, size_type __n)
 243     {
 244       if (__builtin_expect(__n != 0 && __p != 0, true))
 245         {
 246           const size_t __bytes = __n * sizeof(_Tp);
 247           if (__bytes > static_cast<size_t>(_S_max_bytes) || _S_force_new > 0)
 248             ::operator delete(__p);
 249           else
 250             {
 251               _Obj* volatile* __free_list = _M_get_free_list(__bytes);
 252               _Obj* __q = reinterpret_cast<_Obj*>(__p);
 253
 254               __scoped_lock sentry(_M_get_mutex());
 255               __q ->_M_free_list_link = *__free_list;
 256               *__free_list = __q;
 257             }
 258         }
 259     }
 260
 261 _GLIBCXX_END_NAMESPACE
 262
 263 #endif