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_KERNEL_NOTIFICATIONS_INTERFACE_H
 6  #define BITCOIN_KERNEL_NOTIFICATIONS_INTERFACE_H
 7  
 8  #include <cstdint>
 9  #include <variant>
10  
11  class CBlockIndex;
12  enum class SynchronizationState;
13  struct bilingual_str;
14  
15  namespace kernel {
16  
17  //! Result type for use with std::variant to indicate that an operation should be interrupted.
18  struct Interrupted{};
19  enum class Warning;
20  
21  
22  //! Simple result type for functions that need to propagate an interrupt status and don't have other return values.
23  using InterruptResult = std::variant<std::monostate, Interrupted>;
24  
25  template <typename T>
26  bool IsInterrupted(const T& result)
27  {
28      return std::holds_alternative<kernel::Interrupted>(result);
29  }
30  
31  /**
32   * A base class defining functions for notifying about certain kernel
33   * events.
34   */
35  class Notifications
36  {
37  public:
38      virtual ~Notifications() = default;
39  
40      [[nodiscard]] virtual InterruptResult blockTip(SynchronizationState state, const CBlockIndex& index, double verification_progress) { return {}; }
41      virtual void headerTip(SynchronizationState state, int64_t height, int64_t timestamp, bool presync) {}
42      virtual void progress(const bilingual_str& title, int progress_percent, bool resume_possible) {}
43      virtual void warningSet(Warning id, const bilingual_str& message) {}
44      virtual void warningUnset(Warning id) {}
45  
46      //! The flush error notification is sent to notify the user that an error
47      //! occurred while flushing block data to disk. Kernel code may ignore flush
48      //! errors that don't affect the immediate operation it is trying to
49      //! perform. Applications can choose to handle the flush error notification
50      //! by logging the error, or notifying the user, or triggering an early
51      //! shutdown as a precaution against causing more errors.
52      virtual void flushError(const bilingual_str& message) {}
53  
54      //! The fatal error notification is sent to notify the user when an error
55      //! occurs in kernel code that can't be recovered from. After this
56      //! notification is sent, whatever function triggered the error should also
57      //! return an error code or raise an exception. Applications can choose to
58      //! handle the fatal error notification by logging the error, or notifying
59      //! the user, or triggering an early shutdown as a precaution against
60      //! causing more errors.
61      virtual void fatalError(const bilingual_str& message) {}
62  };
63  } // namespace kernel
64  
65  #endif // BITCOIN_KERNEL_NOTIFICATIONS_INTERFACE_H