[Freeswitch-dev] Safely Traversing call lists

[Michael Jerris]

check out similar function that could show you how to do the locking and iterating safely

switch_core_session_hupall_matching_var_ans
 

> On Sep 15, 2015, at 7:43 AM, Ronnie Beck <ronybeck at themenz.biz> wrote:
> 
> Hi All,
> 
> I have just a small question about the thread safety of the following code:
> 
> switch_console_callback_match_t *callList = switch_core_session_findall();
> for( node = callList->head; node; node = node->next )
> {
>     switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG, "(%s) 
> Checking session '%s'\n", __FUNCTION__,  node->val);
> }
> 
> I just want to check some specific channel variables on all the active 
> calls on a Freeswitch server.  However it seems to me that while 
> traversing the list, it is possible that "node" could be deleted by 
> freeswitch while my code is still using it.  Is there some sort of 
> protection I should be doing in order to safely traverse the list and 
> investigate each session?
> 
> I thought I could lock each session as I interrogate the session however 
> this doesn't protect against the situation where the "next" node is 
> deleted as my code switches to that node.  In C++, if you traverse a 
> list with an iterator, changes to the list invalidate the iterator.  So 
> one must obtain a new iterator each time the list is changed.   But I 
> don't see how to do this with the list provided by 
> switch_core_session_findall().
> 
> Any tips?
> 
> Cheers,
> 
> Ronnie Beck
> 
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
> 
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://wiki.freeswitch.org
> http://www.cluecon.com
> 
> FreeSWITCH-dev mailing list
> FreeSWITCH-dev at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-dev
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-dev
> http://www.freeswitch.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.freeswitch.org/pipermail/freeswitch-dev/attachments/20151012/e548e131/attachment.html