1 | #pragma once |
2 | #include <atomic> |
3 | #include <memory> |
4 | #include <Common/ActionLock.h> |
5 | |
6 | |
7 | namespace DB |
8 | { |
9 | |
10 | /// An atomic variable that is used to block and interrupt certain actions. |
11 | /// If it is not zero then actions related with it should be considered as interrupted. |
12 | /// Uses shared_ptr and the lock uses weak_ptr to be able to "hold" a lock when an object with blocker has already died. |
13 | class ActionBlocker |
14 | { |
15 | public: |
16 | ActionBlocker() : counter(std::make_shared<Counter>(0)) {} |
17 | |
18 | bool isCancelled() const { return *counter > 0; } |
19 | |
20 | /// Temporarily blocks corresponding actions (while the returned object is alive) |
21 | friend class ActionLock; |
22 | ActionLock cancel() { return ActionLock(*this); } |
23 | |
24 | /// Cancel the actions forever. |
25 | void cancelForever() { ++(*counter); } |
26 | |
27 | /// Returns reference to counter to allow to watch on it directly. |
28 | const std::atomic<int> & getCounter() const { return *counter; } |
29 | |
30 | private: |
31 | using Counter = std::atomic<int>; |
32 | using CounterPtr = std::shared_ptr<Counter>; |
33 | |
34 | CounterPtr counter; |
35 | }; |
36 | |
37 | |
38 | } |
39 | |