Mailing-List: contact dev-help@httpd.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@httpd.apache.org
Message-ID: <000701c1c494$9888a360$6501a8c0@sashimi>
From: "Bill Stoddard" <bill@wstoddard.com>
To: "Cliff Woolley" <jwoolley@virginia.edu>
Cc: <dev@httpd.apache.org>, "APR Development List" <dev@apr.apache.org>
References: 
 <Pine.LNX.4.44.0203041826010.1666-100000@deepthought.cs.virginia.edu>
Subject: Re: apr_file_open() and caching file descriptors
Date: Tue, 5 Mar 2002 17:24:57 -0500
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

Haven't had much time to think about this today, but I did discover that the XTHREAD
support in win32 apr_file io is seriously broken. apr_file_open(APR_XTHREAD) on Windows
should -not- be creating the overlapped structure and the io completion event. If an open
file is being shared across thread, each thread should have it's own instance of
apr_file_t with its own instance of the overlapped structure and the completion event. As
it is now, if two threads both try to read from a file opened for overlapped i/o at the
same time, thread 1 might get the io completion notification for the io issued by thread 2
or visa-versa. Not good.

Bill

> On Mon, 4 Mar 2002, Bill Stoddard wrote:
>
> > > apr_file_open(yadda,..., APR_XTHREAD|APR_DO_NOT_REGISTER_CLEANUP, r->pool);
>
> I don't conceptually have a problem with the APR_NO_CLEANUP flag (or
> whatever it would be called), but I do have a problem with using
> apr_os_file_get/apr_os_file_put for this.  There has got to be a better
> way.  (For one thing, your APR_XTHREAD flag is meaningless if you do
> that.)
>
> > Rather than an option to not register a cleanup, perhaps a function to
> > kill the cleanup would be more generally useful.
> >
> > apr_file_kill_cleanups(apr_file_t *file);
>
> You still have a problem with the apr_file_t disappearing when r->pool
> goes away, meaning you'd still need the apr_os_file_get/put thing, which
> just doesn't seem like a good idea to me.  There has got to be a good way
> to do this... I'll keep thinking on it and get back to you asap.
>
> --Cliff
>
> --------------------------------------------------------------
>    Cliff Woolley
>    cliffwoolley@yahoo.com
>    Charlottesville, VA
>
>