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chriskohlhoff / asio

Asio C++ Library
http://think-async.com/Asio
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Added public getter for `concurrency_hint` on the io_context. #1254

Open klemens-morgenstern opened 1 year ago

klemens-morgenstern commented 1 year ago

This can be very useful for other libraries, as they can use it to base their own concurrency policy on it.

I specifically needs this for my async_mutex library. That is, my mutex will be much simpler for single-threaded environments, which I would like to check by querying the io_context.

vinipsmaker commented 1 year ago

This can be very useful for other libraries

I can confirm that. In the Lua bindings I wrote for Boost.Asio, I've created a service just to attach the concurrency hint to the io_context:

https://gitlab.com/emilua/emilua/-/blob/a166738c9f181ccce5dc6aaa92e0d2b14d141140/src/main.ypp#L375

as they can use it to base their own concurrency policy on it

For my own use, I probe the concurrency hint for the current io_context to check whether I can spawn a new thread to call run():

https://gitlab.com/emilua/emilua/-/blob/a166738c9f181ccce5dc6aaa92e0d2b14d141140/src/actor.ypp#L1855