Thread-safe node state built from kernel notifications

1// Copyright (c) 2023-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_KERNEL_NOTIFICATIONS_H
6#define BITCOIN_NODE_KERNEL_NOTIFICATIONS_H
7
8#include <kernel/notifications_interface.h>
9
10#include <sync.h>
11#include <uint256.h>
12
13#include <atomic>
14#include <cstdint>
15#include <functional>
16
17class ArgsManager;
18class CBlockIndex;
19enum class SynchronizationState;
20struct bilingual_str;
21
22namespace kernel {
23enum class Warning;
24} // namespace kernel
25
26namespace node {
27
28class Warnings;
29inline constexpr int DEFAULT_STOPATHEIGHT{0};
30
31//! State tracked by the KernelNotifications interface meant to be used by
32//! mining code, index code, RPCs, and other code sitting above the validation
33//! layer.
34//!
35//! Currently just tracks the chain tip, but could be used to hold other
36//! information in the future, like the last flushed block, pruning
37//! information, etc.
38struct KernelState {
39    bool chainstate_loaded{false};
40    std::optional<uint256> tip_block;
41};
42
43class KernelNotifications : public kernel::Notifications
44{
45public:
46    KernelNotifications(const std::function<bool()>& shutdown_request, std::atomic<int>& exit_status, node::Warnings& warnings)
47        : m_shutdown_request(shutdown_request), m_exit_status{exit_status}, m_warnings{warnings} {}
48
49    [[nodiscard]] kernel::InterruptResult blockTip(SynchronizationState state, const CBlockIndex& index, double verification_progress) override EXCLUSIVE_LOCKS_REQUIRED(!m_tip_block_mutex);
50
51    void headerTip(SynchronizationState state, int64_t height, int64_t timestamp, bool presync) override;
52
53    void progress(const bilingual_str& title, int progress_percent, bool resume_possible) override;
54
55    void warningSet(kernel::Warning id, const bilingual_str& message) override;
56
57    void warningUnset(kernel::Warning id) override;
58
59    void flushError(const bilingual_str& message) override;
60
61    void fatalError(const bilingual_str& message) override;
62
63    void setChainstateLoaded(bool chainstate_loaded) EXCLUSIVE_LOCKS_REQUIRED(!m_tip_block_mutex) {
64        LOCK(m_tip_block_mutex);
65        if (!chainstate_loaded) m_state = {};
66        m_state.chainstate_loaded = chainstate_loaded;
67        m_tip_block_cv.notify_all();
68    }
69
70    //! Block height after which blockTip notification will return Interrupted{}, if >0.
71    int m_stop_at_height{DEFAULT_STOPATHEIGHT};
72    //! Useful for tests, can be set to false to avoid shutdown on fatal error.
73    bool m_shutdown_on_fatal_error{true};
74
75    Mutex m_tip_block_mutex;
76    std::condition_variable m_tip_block_cv GUARDED_BY(m_tip_block_mutex);
77    KernelState m_state GUARDED_BY(m_tip_block_mutex);
78    //! The block for which the last blockTip notification was received.
79    //! It's first set when the tip is connected during node initialization.
80    //! Might be unset during an early shutdown.
81    std::optional<uint256> TipBlock() EXCLUSIVE_LOCKS_REQUIRED(m_tip_block_mutex);
82
83private:
84    const std::function<bool()>& m_shutdown_request;
85    std::atomic<int>& m_exit_status;
86    node::Warnings& m_warnings;
87};
88
89void ReadNotificationArgs(const ArgsManager& args, KernelNotifications& notifications);
90
91} // namespace node
92
93#endif // BITCOIN_NODE_KERNEL_NOTIFICATIONS_H
94