http://lecker.essen.de/~froese/coro/
-M
On 16 Jun 2001 14:33:50 -0400, Russell Leighton wrote:
>
> Is there a user-space implemenation (library?) for coroutines that would work from C?
>
>
> Alan Cox wrote:
>
> > > Can you provide any info and/or examples of co-routines? I'm curious to
> > > see a good example of co-routines' "betterness."
> >
> > With co-routines you don't need
> >
> > 8K of kernel stack
> > Scheduler overhead
> > Fancy locking
> >
> > You don't get the automatic thread switching stuff though.
> >
> > So you might get code that reads like this (note that aio_ stuff works rather
> > well combined with co-routines as it fixes a lack of asynchronicity in the
> > unix disk I/O world)
> >
> > select(....)
> >
> > if(FD_ISSET(copier_fd))
> > run_coroutine(&copier_state);
> >
> > ...
> >
> > and the copier might be something like
> >
> > while(1)
> > {
> > // Yes 1 at a time is dumb but this is an example..
> > // Yes Im ignoring EOF for this
> > if(read(copier_fd, buf[bufptr], 1)==-1)
> > {
> > if(errno==-EWOULDBLOCK)
> > {
> > coroutine_return();
> > continue;
> > }
> > }
> > if(bufptr==255 || buf[bufptr]=='\n')
> > {
> > run_coroutine(run_command, buf);
> > bufptr=0;
> > }
> > else
> > bufptr++;
> > }
> >
> > it lets you express a state machine as a set of multiple such small state
> > machines instead. run_coroutine() will continue a routine where it last
> > coroutine_return()'d from. Thus in the above case we are expressing read
> > bytes until you see a new line cleanly - not mangled in with keeping state
> > in global structures but by using natural C local variables and code flow
> >
> > Alan
> >
> > -
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>
> --
> ---------------------------------------------------
> Russell Leighton russell.leighton@247media.com
> ---------------------------------------------------
>
>
> -
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-- Michael Rothwell rothwell@holly-springs.nc.us
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