Re: [SHEPHERD] [PATCH] service: Improve 'service-list'.

[Alex Kost <alezost@gmail.com>]

Ludovic Courtès (2016-01-26 00:49 +0300) wrote:

> Alex Kost <alezost@gmail.com> skribis:
>
>> Ludovic Courtès (2016-01-25 18:06 +0300) wrote:
>>
>>> Alex Kost <alezost@gmail.com> skribis:
>>>
>>>> From f3d21e3ec8a100a966153d03264639ebe48e8872 Mon Sep 17 00:00:00 2001
>>>> From: Alex Kost <alezost@gmail.com>
>>>> Date: Mon, 25 Jan 2016 11:18:00 +0300
>>>> Subject: [PATCH] service: Improve 'service-list'.
>>>>
>>>> * modules/shepherd/service.scm (service-list): Use
>>>>   'lookup-canonical-service' on each name instead of removing duplicates
>>>>   from the final list.
>>>
>>> [...]
>>>
>>>> diff --git a/modules/shepherd/service.scm b/modules/shepherd/service.scm
>>>> index f84d1dd..94f2aae 100644
>>>> --- a/modules/shepherd/service.scm
>>>> +++ b/modules/shepherd/service.scm
>>>> @@ -871,12 +871,13 @@ Return #f if service is not found."
>>>>  
>>>>  (define (service-list)
>>>>    "Return the list of services currently defined."
>>>> -  (delete-duplicates
>>>> -   (hash-fold (lambda (key services result)
>>>> -                (append services result))
>>>> -              '()
>>>> -              %services)
>>>> -   eq?))
>>>> +  (hash-fold (lambda (name services result)
>>>> +               (let ((service (lookup-canonical-service name services)))
>>>> +                 (if service
>>>> +                     (cons service result)
>>>> +                     result)))
>>>> +             '()
>>>> +             %services))
>>>
>>> OK, except that we know that SERVICE is necessarily true, because the
>>> canonical service for NAME is necessarily among SERVICES.
>>>
>>> So I would remove the ‘if’ and add a comment explaining the above.
>>>
>>> OK with this change?
>>
>> No, the service is not necessarily true.  When a service has several
>> names (e.g., "root" and "shepherd"), then %services table will contain 2
>> entries (with 'root' and 'shepherd' keys and the same (#<<service> …>)
>> value).  So for one of the hash-table entries:
>>
>>   (lookup-canonical-service 'root (list root-service))
>>
>> returns #t, and for the other:
>>
>>   (lookup-canonical-service 'shepherd (list root-service))
>>
>> it returns #f.
>
> Indeed, my bad.
>
> Then OK to push, thanks!

Pushed, thanks!

-- 
Alex