Intel's C++ Asynchronous I/O Library for Windows* Operating Systems

This topic only applies to Windows* OS.

Intel's C/C++ asynchronous I/O (AIO) library implementation for the Windows operating system (on IA-32 (C++ only; does not pertain to DPC++) and Intel® 64 platforms) is similar to the POSIX* AIO library implementation for the Linux* operating system.

The differences between Intel's C/C++ AIO Windows OS implementation and the standard POSIX AIO implementation are listed below:

In struct aiocb,

The Windows OS compatible type

HANDLE

replaces the POSIX AIO type

unsigned int

for the file descriptor

aio_fildes.

The type

intptr_t

replaces the POSIX AIO types

ssize_t

and

__off_t

The structure specifying the signal event descriptor, struct sigevent is similar to the Linux* operating system implementation of the POSIX AIO library. It differs from the Linux* implementation in the following ways:

Signal notification and non-notification for thread call-back is supported

Signal notification on completion of the AIO operation is not
supported

This is true for programs that were already written for Linux/Unix and ported to Windows OS that wish to setup an AIO completion handler without the name of the handler set in the

aiocb struct

. Because of the way that signals are supported in Windows, this is impossible to implement. For new applications, or to port existing applications, the programmer should set the name of the handler before calling the

aio_read

aio_write

routines. For example:

static void aio_CompletionRoutine(sigval_t sigval)
{
    // … code …
}

… code …

my_aio.aio_sigevent.sigev_notify          = SIGEV_THREAD;
my_aio.aio_sigevent.sigev_notify_function = aio_CompletionRoutine;

The POSIX AIO library and the Microsoft* SDK provide similar AIO functions. The main difference between the POSIX AIO functions and the Windows operating system-based AIO functions is that while POSIX allows you to execute AIO operations with any file, the Windows operating system executes AIO operations only with files flagged with FILE_FLAG_OVERLAPPED.

Intel's asynchronous I/O library functions listed below are all based on POSIX AIO functions. They are defined in the

aio.h

file.