Bug 18207

Summary:	TpConnectionManager:got-info sometimes fires before tp_list_connection_managers' callback fires
Product:	Telepathy	Reporter:	Will Thompson <will>
Component:	tp-glib	Assignee:	Telepathy bugs list <telepathy-bugs>
Status:	RESOLVED FIXED	QA Contact:	Telepathy bugs list <telepathy-bugs>
Severity:	normal
Priority:	medium	CC:	mardy, murrayc
Version:	unspecified
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Will Thompson 2008-10-24 10:06:30 UTC

tp_list_connection_managers is implemented as follows:

 * Asynchronously, call ListActivableNames
 * For each returned name, if it looks like a connection manager, add it to a map from name ⇒ TpCM
 * Asynchronously, call ListNames
 * For each returned name, if it looks like a CM and isn't already in the map, add it.
 * Now call the callback passed to tp_list_connection_managers

When you construct a TpCM, an idle callback is added to read the .manager file; when it's read, got-info fires on the TpCM.

The intention is that when tp_list_connection_managers calls the user-supplied callback, none of the CMs have had their .manager files read, or been introspected. However, the idle callbacks to read from the .manager file might have already been called, so any given TpCM's got-info(CACHED) signal might already have fired. So the callback gets a list of TpCMs in different states.

This is undesirable. :-)

Comment 1 Will Thompson 2008-10-27 03:23:07 UTC

This is actually worse than I thought: sometimes introspecting a running CM also happens before the callback is called!

Comment 2 Will Thompson 2008-10-28 05:38:13 UTC

I was apparently wrong about introspection of a running CM happening before the callback fires, and think I have a solution for the original bug.

Comment 3 Will Thompson 2008-10-29 05:45:51 UTC

Also, if the .manager file is not found, got-info is never emitted. However, if it is found but reading it fails, got-info (NONE) is emitted.

Comment 4 Simon McVittie 2009-02-04 11:16:25 UTC

http://git.collabora.co.uk/?p=user/smcv/telepathy-glib-smcv.git;a=shortlog;h=refs/heads/cm contains an untested fix for failure to emit got-info if no .manager file exists. The API needs fixing (Bug #18291), this is only a short-term solution.

Users of TpConnectionManager can avoid the problem that got-info might already have been fired by looking at tp_c_m->info_source directly. (Again, this is a short-term fix for what's already there, not a long-term solution.)

Adding mardy to Cc since telepathy-mission-control is interested in this API too.

Comment 5 Alberto Mardegan 2009-02-04 23:41:50 UTC

(In reply to comment #4)
> http://git.collabora.co.uk/?p=user/smcv/telepathy-glib-smcv.git;a=shortlog;h=refs/heads/cm
> contains an untested fix for failure to emit got-info if no .manager file
> exists. The API needs fixing (Bug #18291), this is only a short-term solution.

I didn't try your patch yet, but it seems to me by looking at the code, that the problem also occurs if manager_file is NULL, in which case tp_connection_manager_read_file() won't be executed even with your last change.

Comment 6 Simon McVittie 2009-02-16 10:00:33 UTC

Fixed in 0.7.26

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