Re: asynchronous make(1), anyone?

[matthew sporleder <msporleder%gmail.com@localhost>]

On Sat, Apr 14, 2012 at 9:36 AM, Eric Radman <ericshane%eradman.com@localhost> 
wrote:
> On Sat, Apr 14, 2012 at 12:09:06AM -0400, James K. Lowden wrote:
>> On Wed, 11 Apr 2012 20:15:00 -0500
>> Eric Radman <ericshane%eradman.com@localhost> wrote:
>>
>> > Yes, I've been looking for such a tool for some time, and finally
>> > wrote such utility
>>
>> Nice.  I have a suggestion to simplify it.
>>
>> Small Tools theory suggests two distinct concerns:
>>
>> 1.  detecting an event
>> 2.  acting on the event
>>
>> If your entr(1) simply wrote the name of the changed file to a FIFO, it
>> wouldn't need to control a child process.  Pretend:
>>
>>       $ intr -d $HOME/project -f $HOME/project/notify &
>>       $ grep \.c$ $HOME/project/notify | \
>>         while read F
>>         do
>>               make $(basename $F .c).o
>>         done
>>
>> It could be expanded to monitor anything recognized by kqueue.
>
> This is a more general facility, and has the nice property of giving the
> shell script the name of each file that changed. I'm a little surprised
> that this kind of a tool isn't in base. It's possible to write this kind
> of a loop in Linux using inotify-tools, although their interface is
> cumbersome.
>
>> What happens if 1000 files suddenly appear?  I assume the shell won't
>> empty the FIFO as fast as intr can respond to kqueue.  If the queue is
>> exhausted, the above has the good property (to my mind) of being
>> self-limiting.
>
> This is somewhat different than what entr is trying to accomplish.
> Namely, I don't want to respond to every file change event. As an
> example, it's not uncommon for version control software to update a
> large set of files when they're submitted, but we don't want to run the
> utility one for each file that is modified. To combat this entr ignores
> events until the test runner or build program returns.
>
> Eric

I realize this is a little simpler than you're looking for..

#!/bin/sh

files()
{
  grep ':' Makefile|sed -E 's/.+://g'
}

newest=$(ls -tr1 $(files)|tail -1);
ntime=$(stat -f "%m" ${newest});

while :
do
  newest=$(ls -tr1 $(files)|tail -1);
  nexttime=$(stat -f "%m" ${newest});
  if [ ${nexttime} -gt ${ntime} ]
  then
    ntime=${nexttime};
    make;
  fi
  sleep 2;
done