1// Copyright (c) 2016-present The Bitcoin Core developers
2// Distributed under the MIT software license, see the accompanying
3// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5#ifndef BITCOIN_UTIL_THREADINTERRUPT_H
6#define BITCOIN_UTIL_THREADINTERRUPT_H
7
8#include <sync.h>
9#include <util/time.h>
10
11#include <atomic>
12#include <condition_variable>
13
14/**
15 * A helper class for interruptible sleeps. Calling operator() will interrupt
16 * any current sleep, and after that point operator bool() will return true
17 * until reset.
18 *
19 * This class should not be used in a signal handler. It uses thread
20 * synchronization primitives that are not safe to use with signals. If sending
21 * an interrupt from a signal handler is necessary, the \ref SignalInterrupt
22 * class can be used instead.
23 */
24
25class CThreadInterrupt
26{
27public:
28    using Clock = std::chrono::steady_clock;
29
30    CThreadInterrupt();
31
32    virtual ~CThreadInterrupt() = default;
33
34    /// Return true if `operator()()` has been called.
35    virtual bool interrupted() const;
36
37    /// An alias for `interrupted()`.
38    virtual explicit operator bool() const;
39
40    /// Interrupt any sleeps. After this `interrupted()` will return `true`.
41    virtual void operator()() EXCLUSIVE_LOCKS_REQUIRED(!mut);
42
43    /// Reset to an non-interrupted state.
44    virtual void reset();
45
46    /// Sleep for the given duration.
47    /// @retval true The time passed.
48    /// @retval false The sleep was interrupted.
49    virtual bool sleep_for(Clock::duration rel_time) EXCLUSIVE_LOCKS_REQUIRED(!mut);
50
51private:
52    std::condition_variable cond;
53    Mutex mut;
54    std::atomic<bool> flag;
55};
56
57#endif // BITCOIN_UTIL_THREADINTERRUPT_H
58