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

[Ludovic Courtès]

Alex Kost <address@hidden> skribis:

> Ludovic Courtès (2016-01-25 18:06 +0300) wrote:
>
>> Alex Kost <address@hidden> skribis:
>>
>>> From f3d21e3ec8a100a966153d03264639ebe48e8872 Mon Sep 17 00:00:00 2001
>>> From: Alex Kost <address@hidden>
>>> 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!

Ludo’.