How do I detect when an AIO operation finished without spinning?

Question

In C you might be able to use AIO to do IO in the background without hanging if the IO takes a while, and without the unnecessary creation of threads.

But is there a way I can put a callback function, or manually wait for the AIO operation to end (i.e., like pthread_join()), besides busy waiting like so?

// Start async operation
// Do work
while (aio_error(some_aiocb) == EINPROGRESS);
// Check if async operation succeeded, etc.

Answer 1

The product I work on is a high-performance messaging system. One of its components is a high-speed message storage. It uses aio_suspend() to wait for one or more async operations to complete. It supports a timeout. It works well for us.

I have read that there is another method using an "undocumented" function io_set_eventfd() that lets you use epoll. Here's some unofficial doc that I found. But I have not tried it, so cannot give any guidance.