Filter called more than once...

[Havoc Pennington]

Krishna R wrote:
> The problem seems to be with me returning 
> DBUS_HANDLER_RESULT_NOT_YET_HANDLED in the filter func! Atleast the 
> problem went away when i changed it to HANDLED.
> 
> Questions:
> 
> How is NOT_YET_HANDLED supposed to work?

For a single message there may be multiple handlers that apply; if one 
of them returns HANDLED, then additional handlers would not be called. 
In general NOT_YET_HANDLED is correct for signals, because usually 
everyone interested in a signal should get it. Usually HANDLED is 
correct for method calls (assuming you really handled it, i.e. sent a 
method return message). If nobody returns HANDLED for a method call, 
then libdbus will send an error reply to that call as a default way of 
handling it.

> 1.  It should not call the same recv function again if  it already  
> returned NOT_YET _HANDLED. Correct?

Yes. The only exception I can think of is that if there's an 
out-of-memory error during dispatch, it's possible the dispatch restarts 
with the first handler. I'm not sure how this works offhand.

> 2.  If a signal is sent out and 2 process are listening for it, if one 
> process handles the signal and return HANDLED will the other process 
> still get the signal?

The handlers in one process will have no effect on any other process. 
The HANDLED/NOT_YET_HANDLED return value only controls which handlers 
libdbus will call in the current process.

> Unrelated to the above problem,
> I read in one of the email threads here that if this kind of stuff is 
> done, you need to do dbus_threads_init_default().

It could be related, if you had two threads and no locking, then you 
might expect things to go haywire which might include dispatching the 
same message twice.

> Is there a 
> corresponding deinit() when the thread is killed?

Only dbus_shutdown() which shuts down the entire library (you must 
free/unref any memory from libdbus that you own, prior to dbus_shutdown())

threads_init and dbus_shutdown() are for the whole process, not for 
individual threads.

Havoc