Mohammad's Q2 2024 Update

By Mohammad Nejati on

Jul 10, 2024

The following is an overview of some projects I have been working on in the last few months:

Boost.Beast

Besides addressing user issues and typical bug fixes, here are a couple of contributions to the Boost.Beast project that I find interesting:

Deprecating beast::ssl_stream and beast::flat_stream

The beast::flat_stream was originally designed to consolidate buffer sequences into a single intermediate buffer, reducing the number of I/O operations required when writing these sequences to a stream that lacks scatter/gather support. However, after Asio improved the performance of write operations in ssl::stream by linearizing gather-write buffer sequences, the necessity for beast::ssl_stream and beast::flat_stream has decreased. Their continued inclusion has caused confusion among new users and added unnecessary complexity to the documentation and code snippets. Consequently, these streams are now deprecated, and the use of asio::ssl::stream is recommended in the documentation, examples, and code snippets.

Note: Existing code will remain functional, as beast::ssl_stream has been redefined as a type that publicly inherits from asio::ssl::stream.

Simplifying C++20 Coroutine Examples

The latest Asio release introduces several changes that significantly reduce code complexity and noise. Previously, we had to redefine IO object types with an executor that has a default completion token type, like this:

using tcp_socket = asio::as_tuple_t<asio::deferred_t>::as_default_on_t<asio::ip::tcp::socket>;

With the new Asio release, asio::deferred is now the default completion token, eliminating the need to redefine IO objects with custom executors. Now, these work out of the box:

auto n = co_await http::async_read(stream, buffer, res);
// Or with a partial completion token:
auto [ec, n] = co_await http::async_read(stream, buffer, res, asio::as_tuple);

Using these features and the new asio::cancel_after functionality, all the C++20 coroutine examples in Beast have been refactored to be more concise and clear. Additionally, a task_group has been added to the advanced_server_flex_awaitable example to demonstrate a graceful shutdown process by propagating a cancellation signal to all session subtasks.

Adding New Fuzzing Targets

In this release, we addressed two bug reports that were caught by fuzzing the code: #2879 and #2861. Thanks to tyler92, we have added several fuzzing targets to the project. These targets now fuzz the code with each pull request and at scheduled times throughout the day.

Boost.Http.IO

As the Http.Proto project continues to mature, we have begun enhancing the Http.Io examples to ensure our sans-io API aligns closely with the evolving requirements of the I/O layer. To start, I have introduced a basic C++20 coroutine client example, which will later be expanded into a tool similar to curl.

Boost-Gecko

Boost-Gecko now features a new index for the learn section of the updated Boost website and a new crawler for website-v2-docs. This update allows users to search within the documentation in the learn section using the website’s search dialog. The crawling process and index record uploads are automated through a GitHub workflow, requiring minimal maintenance for each Boost release.