memory_pool_impl.h revision a51ef01822ac68061a1d6e686389cfbcb0e1f8da 
1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef CHRE_UTIL_MEMORY_POOL_IMPL_H_
18#define CHRE_UTIL_MEMORY_POOL_IMPL_H_
19
20#include "chre/util/memory_pool.h"
21
22#include <utility>
23
24namespace chre {
25template<typename ElementType, size_t kSize>
26MemoryPool<ElementType, kSize>::MemoryPool() {
27  // Initialize the free block list. The initial condition is such that each
28  // block points to the next as being empty. The mFreeBlockCount is used to
29  // ensure that we never allocate out of bounds so we don't need to worry about
30  // the last block referring to one that is non-existent.
31  for (size_t i = 0; i < kSize; i++) {
32    blocks()[i].mNextFreeBlockIndex = i + 1;
33  }
34}
35
36template<typename ElementType, size_t kSize>
37template<typename... Args>
38ElementType *MemoryPool<ElementType, kSize>::allocate(Args&&... args) {
39  if (mFreeBlockCount == 0) {
40    return nullptr;
41  }
42
43  size_t blockIndex = mNextFreeBlockIndex;
44  mNextFreeBlockIndex = blocks()[blockIndex].mNextFreeBlockIndex;
45  mFreeBlockCount--;
46
47  return new (&blocks()[blockIndex].mElement)
48      ElementType(std::forward<Args>(args)...);
49}
50
51template<typename ElementType, size_t kSize>
52void MemoryPool<ElementType, kSize>::deallocate(ElementType *element) {
53  uintptr_t elementAddress = reinterpret_cast<uintptr_t>(element);
54  uintptr_t baseAddress = reinterpret_cast<uintptr_t>(&blocks()[0].mElement);
55  size_t blockIndex = (elementAddress - baseAddress) / sizeof(MemoryPoolBlock);
56
57  blocks()[blockIndex].mElement.~ElementType();
58  blocks()[blockIndex].mNextFreeBlockIndex = mNextFreeBlockIndex;
59  mNextFreeBlockIndex = blockIndex;
60  mFreeBlockCount++;
61}
62
63template<typename ElementType, size_t kSize>
64typename MemoryPool<ElementType, kSize>::MemoryPoolBlock
65    *MemoryPool<ElementType, kSize>::blocks() {
66  return reinterpret_cast<MemoryPoolBlock *>(mBlocks);
67}
68
69}  // namespace chre
70
71#endif  // CHRE_UTIL_MEMORY_POOL_IMPL_H_
72