Re: sv sometimes won't issue down request (specifically, after 'sv once xxx')

[Charlie Brady <charlieb-supervision@budge.apana.org.au>]

On Sun, 19 Jul 2009, Earl Chew wrote:

> This defect was submitted against the busybox/runit implementation:
>
> https://bugs.busybox.net/show_bug.cgi?id=461
>
>>  touch /tmp/testservice/down
>>  runsv /tmp/testservice &
>>  sv once /tmp/testservice
>>  sv down /tmp/testservice
>>
>>  The last line attempts to bring down the service, but does nothing.
>
> Denys Vlasenko wrote:
>
>>  I propose just removing this test:
>>
>>          if (svstatus.want == *a)
>>                  return 0;
>>
>>  it seems to be an optimization (and buggy one at that).

Yes it does seem buggy optimisation.

Note that if you simply removed that check, you would change not only the 
'once' behaviour of sv/runsv, but also the behaviour when multiple 'sv d 
xxx' calls are made on a running service. If the optimisation is not 
re-implemented in runsv, then there will be multiple signals and/or custom 
control scripts run where previously there was only one.