Re: aio_cancel

[Jon Grant <jg@xxxxxxxx>]

Michael Kerrisk wrote, On 05/10/11 05:37:
> On Wed, Oct 5, 2011 at 2:08 AM, Jon Grant<jg@xxxxxxxx>  wrote:
[.]
> > Could I ask a related question. When an aio block is cancelled, is there
> > anyway to get back the byte count that was processed? e.g. aio_read, the
> > number of bytes read before the operation was cancelled.
>
> Offhand, I don't know. What happens if you try aio_return() +
> aio_error()? When you find out, send me a patch!

I wrote a small program to write 30MB to a file with aio_write. 
aio_cancel immediately after enqueing. aio_cancel returnend -1, and 
errno was AIO_NOTCANCELED, so I guess it is not possible to cancel in my 
Ubuntu glibc build.



BTW, could this aio_cancel text be updated to clarify if aio_error or 
aio_cancel is returning AIO_ALLDONE.

" This function returns AIO_ALLDONE if
       all requests had already been completed before this call.  When 
some error
       occurs, -1 is returned, and errno is set appropriately."

My assumption would be that it refers to aio_Cancel, but as it follows 
aio_error description.. could be unclear. Maybe the function name can be 
added to the description.


Best regards, Jon
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