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fixpool.hh
1 // -*- coding: utf-8 -*-
2 // Copyright (C) 2011, 2015, 2016 Laboratoire de Recherche et
3 // Développement de l'Epita (LRDE)
4 //
5 // This file is part of Spot, a model checking library.
6 //
7 // Spot is free software; you can redistribute it and/or modify it
8 // under the terms of the GNU General Public License as published by
9 // the Free Software Foundation; either version 3 of the License, or
10 // (at your option) any later version.
11 //
12 // Spot is distributed in the hope that it will be useful, but WITHOUT
13 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 // or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 // License for more details.
16 //
17 // You should have received a copy of the GNU General Public License
18 // along with this program. If not, see <http://www.gnu.org/licenses/>.
19
20 #pragma once
21
22 #include <spot/misc/common.hh>
23 #include <new>
24 #include <cstddef>
25 #include <cstdlib>
26
27 namespace spot
28 {
29
31 class fixed_size_pool
32 {
33 public:
35 fixed_size_pool(size_t size)
36 : freelist_(nullptr), free_start_(nullptr),
37 free_end_(nullptr), chunklist_(nullptr)
38 {
39 const size_t alignement = 2 * sizeof(size_t);
40 size_ = ((size >= sizeof(block_) ? size : sizeof(block_))
41 + alignement - 1) & ~(alignement - 1);
42 }
43
45 ~fixed_size_pool()
46 {
47 while (chunklist_)
48 {
49 chunk_* prev = chunklist_->prev;
50 free(chunklist_);
51 chunklist_ = prev;
52 }
53 }
54
56 void*
57 allocate()
58 {
59 block_* f = freelist_;
60 // If we have free blocks available, return the first one.
61 if (f)
62 {
63 freelist_ = f->next;
64 return f;
65 }
66
67 // Else, create a block out of the last chunk of allocated
68 // memory.
69
70 // If all the last chunk has been used, allocate one more.
71 if (free_start_ + size_ > free_end_)
72 {
73 const size_t requested = (size_ > 128 ? size_ : 128) * 8192 - 64;
74 chunk_* c = reinterpret_cast<chunk_*>(malloc(requested));
75 if (!c)
76 throw std::bad_alloc();
77 c->prev = chunklist_;
78 chunklist_ = c;
79
80 free_start_ = c->data_ + size_;
81 free_end_ = c->data_ + requested;
82 }
83
84 void* res = free_start_;
85 free_start_ += size_;
86 return res;
87 }
88
95 void
96 deallocate (const void* ptr)
97 {
98 SPOT_ASSERT(ptr);
99 block_* b = reinterpret_cast<block_*>(const_cast<void*>(ptr));
100 b->next = freelist_;
101 freelist_ = b;
102 }
103
104 private:
105 size_t size_;
106 struct block_ { block_* next; }* freelist_;
107 char* free_start_;
108 char* free_end_;
109 // chunk = several agglomerated blocks
110 union chunk_ { chunk_* prev; char data_[1]; }* chunklist_;
111 };
112 }
spot
Definition: graph.hh:33
spot::fixed_size_pool::deallocate
void deallocate(const void *ptr)
Recycle size bytes of memory.
Definition: fixpool.hh:96
spot::fixed_size_pool::fixed_size_pool
fixed_size_pool(size_t size)
Create a pool allocating objects of size bytes.
Definition: fixpool.hh:35
spot::fixed_size_pool::allocate
void * allocate()
Allocate size bytes of memory.
Definition: fixpool.hh:57
spot::fixed_size_pool::~fixed_size_pool
~fixed_size_pool()
Free any memory allocated by this pool.
Definition: fixpool.hh:45
spot::fixed_size_pool
A fixed-size memory pool implementation.
Definition: fixpool.hh:31

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