[PATCH] tevent glib event loop glue

[Jeremy Allison]

On Mon, Feb 22, 2016 at 07:19:36PM +0000, Noel Power wrote:

> Well, I'd like to ask we hold off committing this (at least until the
> attached patches are evaluated), I've discovered an issue that leads me
> to believe that the current implementation wont work. I've come to the
> conclusion that actually going back to the idea of using trace callbacks
> is probably the only viable solution. The main problem with the current
> solution is that if any glib event sources are modified/created/deleted
> in the context of a tevent handler that isn't associated with the
> integration implementation then we don't pick up any of those changes
> (see first patch that modifies the client for a reproducer) This problem

Can you explain this a little better please ?

The patch seems to defer processing the callback
by interposing an immediate event.

What is the purpose of that ? What use case does
this test ?

Cheers,

	Jeremy.

> From c5c92be0ae4dde3f5d09c348f9b20e6ce336869e Mon Sep 17 00:00:00 2001
> From: Noel Power <noel.power at suse.com>
> Date: Mon, 22 Feb 2016 19:17:59 +0000
> Subject: [PATCH 1/2] Adjust test client to create activity in glib event
>  sources from tevent context
> 
> Glib event sources when created/deleted/modified via code called from
> a tevent event loop handler should be detected and processed.
> If glib_prepare is NOT called after such a tevent handler as described
> previously has fired then the affected glib event sources will not be
> monitored by tevent, consequently those glib event sources with ready
> events will not be dispatched.
> ---
>  source3/utils/async-tracker.c | 45 ++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 38 insertions(+), 7 deletions(-)
> 
> diff --git a/source3/utils/async-tracker.c b/source3/utils/async-tracker.c
> index 4b674af..14134d0 100644
> --- a/source3/utils/async-tracker.c
> +++ b/source3/utils/async-tracker.c
> @@ -159,6 +159,21 @@ static void query_cb(GObject      *object,
>  	}
>  }
>  
> +static void query_im_handler(struct tevent_context *ev,
> +			     struct tevent_immediate *im,
> +			     void *private_data)
> +{
> +	struct test_state *state = talloc_get_type_abort(private_data, struct test_state);
> +	tracker_sparql_connection_query_async(
> +			state->connection,
> +			"SELECT ?name nie:mimeType(?s) nfo:fileName(?s) "
> +			"WHERE { {?s nie:url ?name}}",
> +			state->cancellable,
> +			query_cb,
> +			state);
> +	TALLOC_FREE(im);
> +}
> +
>  static void connection_cb(GObject      *object,
>  			  GAsyncResult *res,
>  			  gpointer      user_data)
> @@ -174,13 +189,29 @@ static void connection_cb(GObject      *object,
>  	g_timer_start(state->timer);
>  
>  	if (!error) {
> -		tracker_sparql_connection_query_async(
> -			state->connection,
> -			"SELECT ?name nie:mimeType(?s) nfo:fileName(?s) "
> -			"WHERE { {?s nie:url ?name}}",
> -			state->cancellable,
> -			query_cb,
> -			state);
> +		if (state->loop_type == TEVENT_LOOP) {
> +			/*
> +			 * set up query to run in the context of a
> +			 * tevent 'event'
> +			 */
> +			struct tevent_immediate *im =
> +				tevent_create_immediate(state);;
> +			if (im == NULL) {
> +				g_critical("Could not create immediate event");
> +				cleanup(state);
> +			}
> +			tevent_schedule_immediate(im, state->ev,
> +					  query_im_handler,
> +					  state);
> +		} else {
> +			tracker_sparql_connection_query_async(
> +				state->connection,
> +				"SELECT ?name nie:mimeType(?s) nfo:fileName(?s) "
> +				"WHERE { {?s nie:url ?name}}",
> +				state->cancellable,
> +				query_cb,
> +				state);
> +		}
>  	} else {
>  		g_critical("Could not connect: %s", error->message);
>  		g_error_free(error);
> -- 
> 2.1.4
>