Botan  1.10.17
mem_pool.cpp
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1 /*
2 * Pooling Allocator
3 * (C) 1999-2008 Jack Lloyd
4 * 2005 Matthew Gregan
5 * 2005-2006 Matt Johnston
6 *
7 * Distributed under the terms of the Botan license
8 */
9 
10 #include <botan/internal/mem_pool.h>
11 #include <botan/internal/rounding.h>
12 #include <botan/mem_ops.h>
13 #include <algorithm>
14 #include <exception>
15 
16 namespace Botan {
17 
18 /*
19 * Memory_Block Constructor
20 */
21 Pooling_Allocator::Memory_Block::Memory_Block(void* buf)
22  {
23  buffer = static_cast<byte*>(buf);
24  bitmap = 0;
25  buffer_end = buffer + (BLOCK_SIZE * BITMAP_SIZE);
26  }
27 
28 /*
29 * See if ptr is contained by this block
30 */
31 bool Pooling_Allocator::Memory_Block::contains(void* ptr,
32  size_t length) const
33  {
34  return ((buffer <= ptr) &&
35  (buffer_end >= static_cast<byte*>(ptr) + length * BLOCK_SIZE));
36  }
37 
38 /*
39 * Allocate some memory, if possible
40 */
42  {
43  if(n == 0 || n > BITMAP_SIZE)
44  return 0;
45 
46  if(n == BITMAP_SIZE)
47  {
48  if(bitmap)
49  return 0;
50  else
51  {
52  bitmap = ~bitmap;
53  return buffer;
54  }
55  }
56 
57  bitmap_type mask = (static_cast<bitmap_type>(1) << n) - 1;
58  size_t offset = 0;
59 
60  while(bitmap & mask)
61  {
62  mask <<= 1;
63  ++offset;
64 
65  if((bitmap & mask) == 0)
66  break;
67  if(mask >> 63)
68  break;
69  }
70 
71  if(bitmap & mask)
72  return 0;
73 
74  bitmap |= mask;
75  return buffer + offset * BLOCK_SIZE;
76  }
77 
78 /*
79 * Mark this memory as free, if we own it
80 */
81 void Pooling_Allocator::Memory_Block::free(void* ptr, size_t blocks)
82  {
83  clear_mem(static_cast<byte*>(ptr), blocks * BLOCK_SIZE);
84 
85  const size_t offset = (static_cast<byte*>(ptr) - buffer) / BLOCK_SIZE;
86 
87  if(offset == 0 && blocks == BITMAP_SIZE)
88  bitmap = ~bitmap;
89  else
90  {
91  for(size_t j = 0; j != blocks; ++j)
92  bitmap &= ~(static_cast<bitmap_type>(1) << (j+offset));
93  }
94  }
95 
96 /*
97 * Pooling_Allocator Constructor
98 */
100  {
101  last_used = blocks.begin();
102  }
103 
104 /*
105 * Pooling_Allocator Destructor
106 */
108  {
109  delete mutex;
110  #if 0
111  if(blocks.size())
112  throw Invalid_State("Pooling_Allocator: Never released memory");
113  #endif
114  }
115 
116 /*
117 * Free all remaining memory
118 */
120  {
121  Mutex_Holder lock(mutex);
122 
123  blocks.clear();
124 
125  for(size_t j = 0; j != allocated.size(); ++j)
126  dealloc_block(allocated[j].first, allocated[j].second);
127  allocated.clear();
128  }
129 
130 /*
131 * Allocation
132 */
134  {
135  const size_t BITMAP_SIZE = Memory_Block::bitmap_size();
136  const size_t BLOCK_SIZE = Memory_Block::block_size();
137 
138  Mutex_Holder lock(mutex);
139 
140  if(n <= BITMAP_SIZE * BLOCK_SIZE)
141  {
142  const size_t block_no = round_up(n, BLOCK_SIZE) / BLOCK_SIZE;
143 
144  byte* mem = allocate_blocks(block_no);
145  if(mem)
146  return mem;
147 
148  get_more_core(BOTAN_MEM_POOL_CHUNK_SIZE);
149 
150  mem = allocate_blocks(block_no);
151  if(mem)
152  return mem;
153 
154  throw Memory_Exhaustion();
155  }
156 
157  void* new_buf = alloc_block(n);
158  if(new_buf)
159  return new_buf;
160 
161  throw Memory_Exhaustion();
162  }
163 
164 /*
165 * Deallocation
166 */
167 void Pooling_Allocator::deallocate(void* ptr, size_t n)
168  {
169  const size_t BITMAP_SIZE = Memory_Block::bitmap_size();
170  const size_t BLOCK_SIZE = Memory_Block::block_size();
171 
172  if(ptr == 0 || n == 0)
173  return;
174 
175  Mutex_Holder lock(mutex);
176 
177  if(n > BITMAP_SIZE * BLOCK_SIZE)
178  dealloc_block(ptr, n);
179  else
180  {
181  const size_t block_no = round_up(n, BLOCK_SIZE) / BLOCK_SIZE;
182 
183  std::vector<Memory_Block>::iterator i =
184  std::lower_bound(blocks.begin(), blocks.end(), Memory_Block(ptr));
185 
186  if(i == blocks.end() || !i->contains(ptr, block_no))
187  throw Invalid_State("Pointer released to the wrong allocator");
188 
189  i->free(ptr, block_no);
190  }
191  }
192 
193 /*
194 * Try to get some memory from an existing block
195 */
196 byte* Pooling_Allocator::allocate_blocks(size_t n)
197  {
198  if(blocks.empty())
199  return 0;
200 
201  std::vector<Memory_Block>::iterator i = last_used;
202 
203  do
204  {
205  byte* mem = i->alloc(n);
206  if(mem)
207  {
208  last_used = i;
209  return mem;
210  }
211 
212  ++i;
213  if(i == blocks.end())
214  i = blocks.begin();
215  }
216  while(i != last_used);
217 
218  return 0;
219  }
220 
221 /*
222 * Allocate more memory for the pool
223 */
224 void Pooling_Allocator::get_more_core(size_t in_bytes)
225  {
226  const size_t BITMAP_SIZE = Memory_Block::bitmap_size();
227  const size_t BLOCK_SIZE = Memory_Block::block_size();
228 
229  const size_t TOTAL_BLOCK_SIZE = BLOCK_SIZE * BITMAP_SIZE;
230 
231  // upper bound on allocation is 1 MiB
232  in_bytes = std::min<size_t>(in_bytes, 1024 * 1024);
233 
234  const size_t in_blocks = round_up(in_bytes, BLOCK_SIZE) / TOTAL_BLOCK_SIZE;
235  const size_t to_allocate = in_blocks * TOTAL_BLOCK_SIZE;
236 
237  void* ptr = alloc_block(to_allocate);
238  if(ptr == 0)
239  throw Memory_Exhaustion();
240 
241  allocated.push_back(std::make_pair(ptr, to_allocate));
242 
243  for(size_t j = 0; j != in_blocks; ++j)
244  {
245  byte* byte_ptr = static_cast<byte*>(ptr);
246  blocks.push_back(Memory_Block(byte_ptr + j * TOTAL_BLOCK_SIZE));
247  }
248 
249  std::sort(blocks.begin(), blocks.end());
250  last_used = std::lower_bound(blocks.begin(), blocks.end(),
251  Memory_Block(ptr));
252  }
253 
254 }
void deallocate(void *, size_t)
Definition: mem_pool.cpp:167
void clear_mem(T *ptr, size_t n)
Definition: mem_ops.h:32
Pooling_Allocator(Mutex *mutex)
Definition: mem_pool.cpp:99
void * allocate(size_t)
Definition: mem_pool.cpp:133
unsigned char byte
Definition: types.h:22
T round_up(T n, T align_to)
Definition: rounding.h:22
Allocator * alloc
Definition: bzip2.cpp:29