1 | #pragma once |
---|---|
2 | #include <atomic> |
3 | |
4 | |
5 | namespace DB |
6 | { |
7 | |
8 | class SimpleActionLock; |
9 | |
10 | |
11 | /// Similar to ActionBlocker, but without weak_ptr magic |
12 | class SimpleActionBlocker |
13 | { |
14 | using Counter = std::atomic<int>; |
15 | Counter counter = 0; |
16 | |
17 | public: |
18 | |
19 | SimpleActionBlocker() = default; |
20 | |
21 | bool isCancelled() const { return counter > 0; } |
22 | |
23 | /// Temporarily blocks corresponding actions (while the returned object is alive) |
24 | friend class SimpleActionLock; |
25 | inline SimpleActionLock cancel(); |
26 | |
27 | /// Cancel the actions forever. |
28 | void cancelForever() { ++counter; } |
29 | }; |
30 | |
31 | |
32 | /// Blocks related action while a SimpleActionLock instance exists |
33 | class SimpleActionLock |
34 | { |
35 | SimpleActionBlocker * block = nullptr; |
36 | |
37 | public: |
38 | |
39 | SimpleActionLock() = default; |
40 | |
41 | explicit SimpleActionLock(SimpleActionBlocker & block_) : block(&block_) |
42 | { |
43 | ++block->counter; |
44 | } |
45 | |
46 | SimpleActionLock(const SimpleActionLock &) = delete; |
47 | |
48 | SimpleActionLock(SimpleActionLock && rhs) noexcept |
49 | { |
50 | *this = std::move(rhs); |
51 | } |
52 | |
53 | SimpleActionLock & operator=(const SimpleActionLock &) = delete; |
54 | |
55 | SimpleActionLock & operator=(SimpleActionLock && rhs) noexcept |
56 | { |
57 | if (block) |
58 | --block->counter; |
59 | |
60 | block = rhs.block; |
61 | rhs.block = nullptr; |
62 | |
63 | return *this; |
64 | } |
65 | |
66 | ~SimpleActionLock() |
67 | { |
68 | if (block) |
69 | --block->counter; |
70 | } |
71 | }; |
72 | |
73 | |
74 | SimpleActionLock SimpleActionBlocker::cancel() |
75 | { |
76 | return SimpleActionLock(*this); |
77 | } |
78 | |
79 | } |
80 |