spot  0.9.2
mspool.hh
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1 // Copyright (C) 2011 Laboratoire de Recherche et Developpement de
2 // l'Epita (LRDE)
3 //
4 // This file is part of Spot, a model checking library.
5 //
6 // Spot is free software; you can redistribute it and/or modify it
7 // under the terms of the GNU General Public License as published by
8 // the Free Software Foundation; either version 2 of the License, or
9 // (at your option) any later version.
10 //
11 // Spot is distributed in the hope that it will be useful, but WITHOUT
12 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 // or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 // License for more details.
15 //
16 // You should have received a copy of the GNU General Public License
17 // along with Spot; see the file COPYING. If not, write to the Free
18 // Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
19 // 02111-1307, USA.
20 
21 #ifndef SPOT_MISC_MSPOOL_HH
22 # define SPOT_MISC_MSPOOL_HH
23 
24 #include <new>
25 #include <cstddef>
26 #include <cstdlib>
27 #include <cassert>
28 #include "misc/hash.hh"
29 
30 namespace spot
31 {
32 
35  {
36  static const size_t alignment_ = 2 * sizeof(size_t) - 1;
37  public:
40  : free_start_(0), free_end_(0), chunklist_(0)
41  {
42  }
43 
46  {
47  while (chunklist_)
48  {
49  chunk_* prev = chunklist_->prev;
50  free(chunklist_);
51  chunklist_ = prev;
52  }
53  }
54 
55  size_t fixsize(size_t size) const
56  {
57  if (size < sizeof(block_))
58  size = sizeof(block_);
59 
60  return (size + alignment_ - 1) & ~(alignment_ - 1);
61  }
62 
64  void*
65  allocate(size_t size)
66  {
67  size = fixsize(size);
68 
69  block_*& f = freelist_[size];
70  // If we have free blocks available, return the first one.
71  if (f)
72  {
73  block_* first = f;
74  f = f->next;
75  return first;
76  }
77 
78  // Else, create a block out of the last chunk of allocated
79  // memory.
80 
81  // If all the last chunk has been used, allocate one more.
82  if (free_start_ + size > free_end_)
83  {
84  const size_t requested = (size > 128 ? size : 128) * 8192 - 64;
85  chunk_* c = reinterpret_cast<chunk_*>(malloc(requested));
86  if (!c)
87  throw std::bad_alloc();
88  c->prev = chunklist_;
89  chunklist_ = c;
90 
91  free_start_ = c->data_ + size;
92  free_end_ = c->data_ + requested;
93  }
94 
95  void* res = free_start_;
96  free_start_ += size;
97  return res;
98  }
99 
109  void
110  deallocate (const void* ptr, size_t size)
111  {
112  assert(ptr);
113  size = fixsize(size);
114  block_* b = reinterpret_cast<block_*>(const_cast<void*>(ptr));
115  block_*& f = freelist_[size];
116  b->next = f;
117  f = b;
118  }
119 
120  private:
121  struct block_ { block_* next; };
122  Sgi::hash_map<size_t, block_*> freelist_;
123  char* free_start_;
124  char* free_end_;
125  // chunk = several agglomerated blocks
126  union chunk_ { chunk_* prev; char data_[1]; }* chunklist_;
127  };
128 
129 }
130 
131 #endif // SPOT_MISC_INTVPOOL_HH

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