Messages in this thread |  | | Date | Sat, 16 Jun 2001 14:33:50 -0400 | From | Russell Leighton <> | Subject | Re: threading question |
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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 ---------------------------------------------------
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