usable_lib/seg_allocator.h at master · RyuGuo/usable_lib · GitHub

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
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
#ifndef __SEG_ALLOCATOR_H__
#define __SEG_ALLOCATOR_H__

#include <algorithm>
#include <cstdint>
#include <map>
#include <mutex>
#include <set>

class SegAllocator {
public:
  SegAllocator(void *base, size_t size)
      : base(reinterpret_cast<uintptr_t>(base)), size(size) {
    free_seg_set_siz.clear();
    free_seg_set_off.clear();
    free_seg_set_siz.insert(std::make_pair(size, this->base));
    free_seg_set_off.insert(std::make_pair(this->base, size));
  }

  void *allocate(size_t size) {
    auto iter = free_seg_set_siz.lower_bound(std::make_pair(size, 0UL));
    if (iter == free_seg_set_siz.end()) {
      return nullptr;
    }
    uintptr_t off = iter->second;
    size_t less = iter->first - size;
    if (less > 0) {
      free_seg_set_off.insert(std::make_pair(off + size, less));
      free_seg_set_siz.insert(std::make_pair(less, off + size));
    }
    free_seg_set_off.erase(iter->second);
    free_seg_set_siz.erase(iter);
    return reinterpret_cast<void *>(off);
  }

  void *placement_allocate(void *p, size_t size) {
    uintptr_t off = reinterpret_cast<uintptr_t>(p);

    auto iter = std::upper_bound(
        free_seg_set_off.rbegin(), free_seg_set_off.rend(), off,
        [](const uint64_t a, std::pair<const uint64_t, size_t> b) {
          return a >= b.first;
        });
    if (iter == free_seg_set_off.rend()) {
      return nullptr;
    }
    if (iter->first + iter->second < off + size) {
      return nullptr;
    }
    size_t less = iter->second - size;
    if (less == 0) {
      free_seg_set_off.erase(iter->first);
      free_seg_set_siz.erase(std::make_pair(iter->second, iter->first));
    } else if (iter->first == off) {
      free_seg_set_siz.erase(std::make_pair(iter->second, iter->first));
      free_seg_set_off.erase(iter->first);
      free_seg_set_off.insert(std::make_pair(off, less));
      free_seg_set_siz.insert(std::make_pair(less, off));
    } else if (iter->first + iter->second == off + size) {
      free_seg_set_siz.erase(std::make_pair(iter->second, iter->first));
      iter->second = less;
      free_seg_set_siz.insert(std::make_pair(iter->second, iter->first));
    } else {
      free_seg_set_siz.erase(std::make_pair(iter->second, iter->first));
      iter->second = off - iter->first;
      free_seg_set_siz.insert(std::make_pair(iter->second, iter->first));
      free_seg_set_off.insert(std::make_pair(off + size, less - iter->second));
      free_seg_set_siz.insert(std::make_pair(less - iter->second, off + size));
    }

    return p;
  }

  void deallocate(void *p, size_t size) {
    uintptr_t off = reinterpret_cast<uintptr_t>(p);

    auto next = free_seg_set_off.lower_bound(off), iter = next;
    int flag = 0;
    // check if merge next seg
    if (next != free_seg_set_off.end() && off + size == next->first) {
      flag |= 1;
    }

    if (next != free_seg_set_off.begin()) {
      --next; // prev
      // check if merge prev seg
      if (next != free_seg_set_off.end() && next->first + next->second == off) {
        flag |= 2;
      }
    }

    switch (flag) {
    case 0:
      free_seg_set_siz.insert(std::make_pair(size, off));
      free_seg_set_off.insert(std::make_pair(off, size));
      break;
    case 1:
      free_seg_set_siz.erase(std::make_pair(iter->second, iter->first));
      free_seg_set_siz.insert(
          std::make_pair(iter->second + size, iter->first - size));
      free_seg_set_off.insert(
          std::make_pair(iter->first - size, iter->second + size));
      free_seg_set_off.erase(iter);
      break;
    case 2:
      free_seg_set_siz.erase(std::make_pair(next->second, next->first));
      next->second += size;
      free_seg_set_siz.insert(std::make_pair(next->second, next->first));
      break;
    case 3:
      free_seg_set_siz.erase(std::make_pair(next->second, next->first));
      free_seg_set_siz.erase(std::make_pair(iter->second, iter->first));
      next->second += size + iter->second;
      free_seg_set_off.erase(iter);
      free_seg_set_siz.insert(std::make_pair(next->second, next->first));
      break;
    }
  }

protected:
  std::set<std::pair<size_t, uintptr_t>> free_seg_set_siz;
  std::map<uintptr_t, size_t> free_seg_set_off;
  uintptr_t base;
  size_t size;
};

class SegAllocatorReverse : public SegAllocator {
public:
  SegAllocatorReverse(void *base, size_t size) : SegAllocator(base, size) {}

  void *allocate(size_t size) {
    void *p = SegAllocator::allocate(size);
    if (p == nullptr)
      return nullptr;
    return reverse_ptr(p, size);
  }

  void *placement_allocate(void *p, size_t size) {
    void *rp = SegAllocator::placement_allocate(reverse_ptr(p, size), size);
    if (rp == nullptr)
      return nullptr;
    return p;
  }

  void deallocate(void *p, size_t size) {
    SegAllocator::deallocate(reverse_ptr(p, size), size);
  }

private:
  void *reverse_ptr(void *p, size_t size) {
    return reinterpret_cast<void *>(
        base + this->size - 1 - reinterpret_cast<uintptr_t>(p) + base - size);
  }
};

#endif // __SEG_ALLOCATOR_H__