[PATCH] ruby: make sure the database is closed

[Felipe Contreras]

On Mon, Apr 23, 2012 at 11:43 PM, Ali Polatel <alip at exherbo.org> wrote:
> 2012/4/23 Felipe Contreras <felipe.contreras at gmail.com>:
>> On Mon, Apr 23, 2012 at 5:04 PM, Ali Polatel <alip at exherbo.org> wrote:
>>
>>> I'd rather not do this.
>>> Please read: http://comments.gmane.org/gmane.comp.lang.ruby.general/320324
>>
>> OK, I've read this.. So?
>
> You are one step close to what I thought you had thought.

I don't parse that. I meant that _now_ I've read it.

>> The order in which Ruby's garbage-collector frees the database and
>> other objects is irrelevant, because with this patch we are not
>> manually freeing other objects, only the database.
>
> What I wanted was to make all objects "depending" on the database to be unusable
> once the database object is freed. Seeing that's not practically easy
> I decided to leave
> it to the user.

Well, sure, but if the user has problems, the user can keep the
database object around.

Personally I don't see why an object, like say a query would remain
working correctly after the database is gone, either by calling
.close() directly, or just loosing the pointer to the original object.
I don't think users would expect that, or, even if they somehow found
it useful, that most likely would be very seldom, and hardly worth
worrying about it.

>> Sure, it's _better_ if the user calls close(), even better if it's
>> inside an 'ensure', and even better if blocks are used (which I am
>> using in most cases), but that's not *required*.
>
> If you have such a use case, I'm fine with that patch.
> I might push it in the next few days or get someone else to push it.

I did at some point, not sure if I do now. But that's beside the
point, the point is that it really does happen.

>> The user might just do:
>>
>> def foo
>>  db = Notmuch::Database.new($db_name, :mode => Notmuch::MODE_READ_WRITE)
>> end
>>
>> That's perfectly fine in Ruby (although not ideal), since 'db' will
>> get garbage-collected. But nobody will be able to use the database
>> again until that process is killed.
>>
>> You think that's correct?
>
> Yes that is correct. I have not thought about this.
> I'd say it's a partial misunderstanding on my part due to lack of
> (and/or too much) vodka.

Well, there's only two options.

a) This works:

  def foo
    db = Notmuch::Database.new($db_name, :mode => Notmuch::MODE_READ_WRITE)
  end

(as in; the database gets closed eventually)

b) This works:

  def start_query(search)
    db = Notmuch::Database.new($db_name)
    return db.query(search)
  end

(as in; the query returned would keep working properly)

I personally don't see why anybody would want b), and if they have
problems with code like that, I think it's obvious to see why.

I think we should go for a) and thus apply the patch.

Cheers.

-- 
Felipe Contreras