3 // Copyright (C) 2004 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 2, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // You should have received a copy of the GNU General Public License along
17 // with this library; see the file COPYING. If not, write to the Free
18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
21 // As a special exception, you may use this file as part of a free software
22 // library without restriction. Specifically, if other files instantiate
23 // templates or use macros or inline functions from this file, or you compile
24 // this file and link it with other files to produce an executable, this
25 // file does not by itself cause the resulting executable to be covered by
26 // the GNU General Public License. This exception does not however
27 // invalidate any other reasons why the executable file might be covered by
28 // the GNU General Public License.
34 #include <bits/c++config.h>
36 #include <ext/mt_allocator.h>
37 #include <ext/pool_allocator.h>
39 namespace __gnu_internal
41 __glibcxx_mutex_define_initialized(palloc_init_mutex);
46 // Definitions for __pool_alloc_base.
47 __pool_alloc_base::_Obj* volatile*
48 __pool_alloc_base::_M_get_free_list(size_t __bytes)
50 size_t __i = ((__bytes + (size_t)_S_align - 1) / (size_t)_S_align - 1);
51 return _S_free_list + __i;
55 __pool_alloc_base::_M_get_mutex()
56 { return __gnu_internal::palloc_init_mutex; }
58 // Allocate memory in large chunks in order to avoid fragmenting the
59 // heap too much. Assume that __n is properly aligned. We hold the
62 __pool_alloc_base::_M_allocate_chunk(size_t __n, int& __nobjs)
65 size_t __total_bytes = __n * __nobjs;
66 size_t __bytes_left = _S_end_free - _S_start_free;
68 if (__bytes_left >= __total_bytes)
70 __result = _S_start_free;
71 _S_start_free += __total_bytes;
74 else if (__bytes_left >= __n)
76 __nobjs = (int)(__bytes_left / __n);
77 __total_bytes = __n * __nobjs;
78 __result = _S_start_free;
79 _S_start_free += __total_bytes;
84 // Try to make use of the left-over piece.
87 _Obj* volatile* __free_list = _M_get_free_list(__bytes_left);
88 ((_Obj*)(void*)_S_start_free)->_M_free_list_link = *__free_list;
89 *__free_list = (_Obj*)(void*)_S_start_free;
92 size_t __bytes_to_get = (2 * __total_bytes
93 + _M_round_up(_S_heap_size >> 4));
96 _S_start_free = static_cast<char*>(::operator new(__bytes_to_get));
100 // Try to make do with what we have. That can't hurt. We
101 // do not try smaller requests, since that tends to result
102 // in disaster on multi-process machines.
104 for (; __i <= (size_t) _S_max_bytes; __i += (size_t) _S_align)
106 _Obj* volatile* __free_list = _M_get_free_list(__i);
107 _Obj* __p = *__free_list;
110 *__free_list = __p->_M_free_list_link;
111 _S_start_free = (char*)__p;
112 _S_end_free = _S_start_free + __i;
113 return _M_allocate_chunk(__n, __nobjs);
114 // Any leftover piece will eventually make it to the
118 // What we have wasn't enough. Rethrow.
119 _S_start_free = _S_end_free = 0; // We have no chunk.
120 __throw_exception_again;
122 _S_heap_size += __bytes_to_get;
123 _S_end_free = _S_start_free + __bytes_to_get;
124 return _M_allocate_chunk(__n, __nobjs);
128 // Returns an object of size __n, and optionally adds to "size
129 // __n"'s free list. We assume that __n is properly aligned. We
130 // hold the allocation lock.
132 __pool_alloc_base::_M_refill(size_t __n)
135 char* __chunk = _M_allocate_chunk(__n, __nobjs);
136 _Obj* volatile* __free_list;
143 __free_list = _M_get_free_list(__n);
145 // Build free list in chunk.
146 __result = (_Obj*)(void*)__chunk;
147 *__free_list = __next_obj = (_Obj*)(void*)(__chunk + __n);
148 for (int __i = 1; ; __i++)
150 __current_obj = __next_obj;
151 __next_obj = (_Obj*)(void*)((char*)__next_obj + __n);
152 if (__nobjs - 1 == __i)
154 __current_obj->_M_free_list_link = 0;
158 __current_obj->_M_free_list_link = __next_obj;
163 __pool_alloc_base::_Obj* volatile __pool_alloc_base::_S_free_list[_S_free_list_size];
165 char* __pool_alloc_base::_S_start_free = 0;
167 char* __pool_alloc_base::_S_end_free = 0;
169 size_t __pool_alloc_base::_S_heap_size = 0;
170 } // namespace __gnu_cxx