1// Copyright (c) 2024-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_NODE_TIMEOFFSETS_H
6#define BITCOIN_NODE_TIMEOFFSETS_H
7
8#include <sync.h>
9
10#include <chrono>
11#include <cstddef>
12#include <deque>
13
14namespace node {
15class Warnings;
16} // namespace node
17
18class TimeOffsets
19{
20public:
21    TimeOffsets(node::Warnings& warnings) : m_warnings{warnings} {}
22
23private:
24    //! Maximum number of timeoffsets stored.
25    static constexpr size_t MAX_SIZE{50};
26    //! Minimum difference between system and network time for a warning to be raised.
27    static constexpr std::chrono::minutes WARN_THRESHOLD{10};
28
29    mutable Mutex m_mutex;
30    /** The observed time differences between our local clock and those of our outbound peers. A
31     * positive offset means our peer's clock is ahead of our local clock. */
32    std::deque<std::chrono::seconds> m_offsets GUARDED_BY(m_mutex){};
33
34    node::Warnings& m_warnings;
35
36public:
37    /** Add a new time offset sample. */
38    void Add(std::chrono::seconds offset) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
39
40    /** Compute and return the median of the collected time offset samples. The median is returned
41     * as 0 when there are less than 5 samples. */
42    std::chrono::seconds Median() const EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
43
44    /** Raise warnings if the median time offset exceeds the warnings threshold. Returns true if
45     * warnings were raised. */
46    bool WarnIfOutOfSync() const EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
47};
48
49#endif // BITCOIN_NODE_TIMEOFFSETS_H
50