[PATCH] Add a method to reparent threads to the database.
Steven Allen
steven at stebalien.com
Sun Nov 8 11:15:36 PST 2015
I'm writing high-level rust bindings for notmuch and would like to
enable encapsulation of query logic. That is, I'd like to be able to
write a function that performs a (set of) query(s) and returns a (or a
set of) message(s)/thread(s). I can't do this currently because the
messages/threads can't outlive the query. I could use reference counting
to store the query until all messages/threads have been freed but that
feels messy and shouldn't, strictly speaking, be necessary.
On 11-08-15, Jani Nikula wrote:
> On Sat, 07 Nov 2015, Steven Allen <steven at stebalien.com> wrote:
> > This allows threads yielded from a query to outlive the query.
>
> We have a leaky abstraction in the interface. We don't properly define
> object lifetimes and ownership, but we have slightly vague references to
> them, and the users of the interface pretty much have to respect
> them. We try to hide talloc and its concepts.
>
> I think this patch makes the situation slightly worse.
>
> I'd like to understand why this change is better than just holding on to
> the query object. The memory saving is neglible.
>
> BR,
> Jani.
>
>
> > ---
> > lib/notmuch.h | 11 +++++++++++
> > lib/thread.cc | 6 ++++++
> > 2 files changed, 17 insertions(+)
> >
> > diff --git a/lib/notmuch.h b/lib/notmuch.h
> > index 310a8b8..9a2869b 100644
> > --- a/lib/notmuch.h
> > +++ b/lib/notmuch.h
> > @@ -1188,6 +1188,17 @@ notmuch_tags_t *
> > notmuch_thread_get_tags (notmuch_thread_t *thread);
> >
> > /**
> > + * Reparent a notmuch_thread_t object onto the database.
> > + *
> > + * Calling this function allows a notmuch_thread_t object to outlive its
> > + * query. The query will automatically be reclaimed when the database is
> > + * destroyed but if you want to free its memory before then, you should call
> > + * notmuch_thread_destroy.
> > + */
> > +void
> > +notmuch_thread_own (notmuch_thread_t *thread);
> > +
> > +/**
> > * Destroy a notmuch_thread_t object.
> > */
> > void
> > diff --git a/lib/thread.cc b/lib/thread.cc
> > index 0c937d7..06fa155 100644
> > --- a/lib/thread.cc
> > +++ b/lib/thread.cc
> > @@ -623,3 +623,9 @@ notmuch_thread_destroy (notmuch_thread_t *thread)
> > {
> > talloc_free (thread);
> > }
> > +
> > +void
> > +notmuch_thread_own (notmuch_thread_t *thread)
> > +{
> > + talloc_steal (thread->notmuch, thread);
> > +}
> > --
> > 2.6.2
> >
> > _______________________________________________
> > notmuch mailing list
> > notmuch at notmuchmail.org
> > https://notmuchmail.org/mailman/listinfo/notmuch
--
Steven Allen
(310) 433-5865
((Do Not Email <honeypot at stebalien.com>))
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