Re: [PATCH] Add a method to reparent threads to the database.

[Jani Nikula <jani@nikula.org>]

On Sat, 07 Nov 2015, Steven Allen <steven@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
>
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