blob: 26e096a520a33472a70cd8ea95c0fd8e8561faf7 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
|
// Copyright 2011 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef GESTURES_MEMORY_MANAGER_H_
#define GESTURES_MEMORY_MANAGER_H_
#include <new>
#include "include/logging.h"
#include "include/macros.h"
namespace gestures {
// A simple memory manager class that pre-allocates a size of
// buffer and garbage collects freed variables. It is not intended
// to be used directly. User classes should inherit the
// MemoryManaged wrapper class and use the provided Allocate/Free
// interface instead (see below).
template<typename T>
class MemoryManager {
public:
explicit MemoryManager(size_t size) : buf_(new T[size]),
free_slots_(new T *[size]), used_mark_(new bool[size]()),
max_size_(size), head_(size) {
for (size_t i = 0; i < max_size_; i++)
free_slots_[i] = buf_.get() + i;
}
size_t Size() const { return max_size_ - head_; }
size_t MaxSize() const { return max_size_; }
T* Allocate() {
if (!head_) {
Err("MemoryManager::Allocate: out of space");
return NULL;
}
T* ptr = free_slots_[--head_];
used_mark_[ptr - buf_.get()] = true;
return ptr;
}
bool Free(T* ptr) {
// Check for invalid pointer and double-free
if (ptr < buf_.get() || ptr >= buf_.get() + max_size_) {
Err("MemoryManager::Free: pointer out of bounds");
return false;
}
size_t offset_in_bytes = reinterpret_cast<size_t>(ptr) -
reinterpret_cast<size_t>(buf_.get());
if (offset_in_bytes % sizeof(T)) {
Err("MemoryManager::Free: unaligned pointer");
return false;
}
size_t offset = ptr - buf_.get();
if (!used_mark_[offset]) {
Err("MemoryManager::Free: double-free");
return false;
}
free_slots_[head_++] = ptr;
used_mark_[offset] = false;
return true;
}
private:
std::unique_ptr<T[]> buf_;
std::unique_ptr<T*[]> free_slots_;
std::unique_ptr<bool[]> used_mark_;
size_t max_size_;
size_t head_;
DISALLOW_COPY_AND_ASSIGN(MemoryManager<T>);
};
} // namespace gestures
#endif // MEMORY_MANAGER_H_
|
