Re: io_close proposal

On Sun, May 19, 2002 at 01:31:54PM -0700, Thomas Bushnell, BSG wrote:
> Marcus Brinkmann <[email protected]> writes:
> 
> > Well, the real problem, and the explanation why my idea won't work is this:
> > 
> > If the server sees 1 extant send right, he doesn't know if this is the
> > callers extant send right, or if the number of extant send rights has been
> > 2 and the caller did:
> > 
> > io_close_request(port)
> > mach_port_deallocate(mach_task_self(), port);
> 
> Here, the user has not followed the protocol.  He has the port
> *twice*, and if he wants close actions to work properly, he must call
> io_close_request on *each*.  

Sorry, I was not being clear.  I was arguing here against the idea of
sending the io_close _without sending the port right along with the
message_, which is a different idea from the one I originally proposed.

The point is that the current interruptible RPC stubs expect that the caller
keeps a send right for each send right moved in the message.  I was trying
to think about a way to make io_close work without moving the send right of
the caller to the server.

I think I have showed that such an approach is impossible to work reliably.

I should have given the io_close_request above a different name to
distinguish it from the original proposal.

Thanks,
Marcus

-- 
`Rhubarb is no Egyptian god.' Debian http://www.debian.org [email protected]
Marcus Brinkmann              GNU    http://www.gnu.org    [email protected]
[email protected]
http://www.marcus-brinkmann.de