This is an implementation for Linux of the IEEE 1003.1-2004 (aka POSIX realtime) AIO
functions, utilizing 2.6 kernel's io_ syscalls rather than using pthreads as in glibc.
However, we still need a watcher thread since the Linux io_ syscalls do not match
the AIO specification at all. Therefore we need an extra thread to signal the I/O thread
about events. Nevertheless this scales much better than glibc creating a new thread
for each asynchronous submit.
Just make and you will find aio.o which you can link to your programs using aio_ calls.
You also need to include the proper aio.h file of course. Do not link against -lrt as
this contains glibc's version of AIO.
This aio lib is thread safe. It also builds and works for Android.
AIO only builds with the gcc (still, it is C99 code :) since I use some of the GCC
intrinsics for atomic read/write operations (remember: thread safe!).
I wrote this code for my own purposes (basically a fast backup/restore and forensic tool) so its (C) Sebastian Krahmer. However you can use this library under the terms of the GPL.
Note that you need to open files with the O_DIRECT flag for aio to work
(the test files skip that but you need it to ensure real async operation in kernel)
as well as the memory buffers need to be aligned for disk blocks.