Re: [gnet-dev] Re: Glib win32 iochannels update

[Andrewlanoix aol com]

David,

In ob_server_func(), gnet_conn_readline() calls gnet_io_channel_readline_async() which creates the first watch on the socket with G_IO_IN. 

The second watch is created by send_to() with gnet_conn_write() which calls gnet_io_channel_write_async() which does the G_IO_OUT watch. send_to() is called by the first callback.

I don't know what goes on in *nix but the windows problem is isolated to giowin32.c. socket iochannels on win32 are implemented as one win32 specific thread per socket inochannel.

If I do a select on all conditions, won't it almost always return with saying it can write to the socket?

Where do we go from here?

Andy


In a message dated 5/13/2003 10:50:15 PM Eastern Standard Time, dhelder umich edu writes:

> 
> 
> On Tue, 13 May 2003 Andrewlanoix aol com wrote:
> > I have discovered what the problem is, or at least the first problem.
> > There is an issue with the way the socket threads in glib on win32 are
> > synchronized when you add a second watch to the iochannel.
> >
> > Basically the code checks to see what conditions to look for, G_IO_IN
> > etc across all watches and then does a select() call which goes to
> > sleep on those conditions. It does not wake up until one of those
> > conditions is met. This means that if you do a G_IO_IN, followed by a
> > G_IO_OUT g_io_add_watch() call, the second will not happen until the
> > first call happens on that socket.
> 
> Ugh.  Multiple watches on a single IOChannel causes problems in Linux too.
> Is this problem with the core GLib code or just with the Win32 specific
> code?
> 
> > The simple fix to this problem is to have a timeout on the select()
> > call. When the timeout occurs do a continue; to restart the loop to
> > reload the conditions to select() on. However, I do not know what a
> > reasonable timeout should be. I am going to talk to David and
> > investigate other options.
> 
> Will that work?  The best solution would be to select on all the
> conditions in first place.
> 
> David
> 
> 
> -- 
> David Helder - dhelder umich edu - 
> <http://www.eecs.umich.edu/~dhelder>
> 
> 
> 
>