Messages in this thread |  | | Date | Sat, 16 Jun 2001 17:30:55 -0400 | From | Russell Leighton <> | Subject | Coroutines [was Re: threading question] |
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Any chance this or the equiv could become part of glibc?
This seems a very handy abstraction, in many apps threads would then really only be needed for true parallelism.
Michael Rothwell wrote:
> Try this: > > 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 > > > > > > - > > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > > the body of a message to majordomo@vger.kernel.org > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > Please read the FAQ at http://www.tux.org/lkml/ > > > > -- > > --------------------------------------------------- > > Russell Leighton russell.leighton@247media.com > > --------------------------------------------------- > > > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > -- > Michael Rothwell > rothwell@holly-springs.nc.us
-- --------------------------------------------------- Russell Leighton russell.leighton@247media.com ---------------------------------------------------
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