Re: [Libevent-users] Event priorities

[Ralph Castain <rhc@xxxxxxxxxxxx>]

On Apr 30, 2012, at 5:10 PM, Nick Mathewson wrote:

> On Mon, Apr 30, 2012 at 6:45 PM, Ralph Castain <rhc@xxxxxxxxxxxx> wrote:
> [...]
>> I'll take a look at your branch, but had some further thoughts in the interim. Would a more optimal option be to add the following logic to event_priority_set:
>> 
>> event_priority_set(ev, pri) {
>>    IF <I am in an event> AND
>>        IF <ev->base> EQ <current-base> AND
>>        IF <pri> LT <current-pri>  THEN
>>            <rescan queues on next loop>
>> 
>> In other words, only rescan and start the dispatch phase if the priority of the new event is higher (less-than) that of the current event. If not, then just proceed as we currently do. This avoid unnecessarily restarting the dispatch phase when lower priority events are defined.
>> 
> 
> That doesn't really make sense; event_priority_set is used to set up
> the event, not to add it to the active queue.  You'd want logic like
> this in event_active(), not event_priority_set.

Agreed - your approach is definitely better, IMO. I was glad to see you had similar thoughts.

The branch looks like it does the trick, and I like that it also does not force the re-scan unless the newly activated event is a higher priority.

+1 from me.

Meantime, I gather this was against the current 2.0 trunk as opposed to the 2.0.18 release - I might consider bumping up to it if you think a 2.0.19 is a ways off.


> 
> (This is, btw, more or less the logic in my branch.)
> 
> -- 
> Nick
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