tidy code for asynchronous IO

Question

Whilst asynchronous IO (non-blocking descriptors with select/poll/epoll/kqueue etc) is not the most documented thing on the web, there are a handful of good examples.

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Answer 1

You need to have a main loop that provides async_schedule(), async_foreach(), async_tick() etc. These functions in turn place entries into a global list of methods that will run upon next call to async_tick(). Then you can write code that is much more tidy and does not include any switch statements.

You can just write:

async_schedule(callback, arg, timeout); 

Or:

async_wait(condition, callback, arg, timeout); 

Then your condition can even be set in another thread (provided that you take care of thread safety when accessing that variable).

I have implemented an async framework in C for my embedded project because I wanted to have non-preemptive multitasking and async is perfect for doing many tasks by doing a little bit of work during every iteration of the main loop.

The code is here: https://github.com/mkschreder/fortmax-blocks/blob/master/common/kernel/async.c