Retry

Description

This is a header-only library that provides a simple and efficient way to retry functions based on their return values. The API is straightforward: users pass the target function, a list of values that will trigger a retry if the return value matches, the maximum number of attempts or retry period, and the list of arguments originally passed to their function.

Features

• Supports retrying various function types, including free functions, static member functions, std::function objects, and anonymous lambdas.
• Handles both value and reference return types.
• Allows customization of the maximum retry period or the number of retry attempts.
• Provides options to set custom retry intervals.

Usage

The retry_until and retry_at_intervals_until functions retry the user function until the return value no longer matches the specified list or the attempt/time limit is reached. Examples:

Retry the function for 10 seconds

// User's function
Status join_room(const Member& member, int member_id) {
    // Function implementation
}

// Retry
Member user{"Alice"};
Status status = tsejhuang::retry_until(join_room, {Status::Busy, Status::MaxUsersReached}, std::chrono::seconds{10}, user, 1);

Retry the function for 10 attempts

Status status = tsejhuang::retry_until(join_room, {Status::Busy, Status::MaxUsersReached}, 10, user, 1);

Retry the function for 10 seconds with a 2-second interval

Status status = tsejhuang::retry_at_intervals_until(join_room, {Status::Busy, Status::MaxUsersReached}, std::chrono::seconds{10}, std::chrono::seconds{2}, user, 1);

Retry the function for 10 attempts with a 2-second interval

Status status = tsejhuang::retry_at_intervals_until(join_room, {Status::Busy, Status::MaxUsersReached}, 10, std::chrono::seconds{2}, user, 1);

Handling reference return types

If the return type of the user function is a reference, wrap each value in the list with std::ref or std::cref:

// User's function
const Member& get_current_speaker() {
    // Function implementation
}

// Retry
Member me{"Alice"};
Member other_user1{"Bob"};
Member other_user2{"Carol"};
const auto& speaker = tsejhuang::retry_at_intervals_until(get_current_speaker, {std::cref(other_user1), std::cref(other_user2)}, std::chrono::seconds{10}, std::chrono::seconds{2});

if (speaker != me) {
    // Retry failure
}

API Documentation

See retry.hpp for API documentation and tests for example usage.

Contributing

Contributions are welcome! To contribute:

1. Fork the repository.
2. Create a new branch: git checkout -b feature-name.
3. Commit your changes: git commit -m "Add feature-name".
4. Push the branch: git push origin feature-name.
5. Submit a pull request.

License

This project is licensed under the MIT License.