On Wed, Apr 30, 2014 at 08:44:24AM -0400, Nick Mathewson wrote: > On Wed, Apr 30, 2014 at 8:24 AM, Denis Hainsworth > <de...@alumni.brandeis.edu> wrote: > > I have question I'm hoping will short-cut an investigation I'm doing > > into some inherited code. Essentially we have some real simple code > > which sets up an event with a timer and depending on certain things > > changes the timer during each loop. We are seeing a difference in > > behavior from when it was using 1.x libevent and 2.x. > > > > We call event_set at the start of the code for 60 seconds, and then > > during each loop use event_add to set the timer to however many seconds > > from current time to get to the next minute. Its pretty dumb code and > > there are lots of things wrong with it but it has been working. > > I think you might be mixing something up here; event_set() doesn't set > timeouts; that's in event_add(). > > event_add(), on the other hand, doesn't change callbacks. > > It's not supported to call event_set() on an event that is currently > pending, and it wasn't supported in Libevent 1.x either -- most > programs that do that will get mysterious crashes as the internal data > structures get corrupted. It's like using free()d memory -- some > programs will get away with it, and some programs won't, but it's a > bug either way. > > If you need to call event_set() on an event that might be pending, you > need to call event_del(), then event_set(), then event_add() again. > That's necessary for correctness with Libevent 1.x and 2.x as well. > > My apologies if I haven't understood the situation, though; if you > could post a tiny code sample demonstrating the behavior you're > talking about, that would probably help track down the issue.
Thanks Nick, I was trying to keep the question simple as there are a number of extra complexities we are dealing with like that there is a python layer in between libevent and the script. All I need to know right now is when event_add is called on an existing event to change the timer (which is a valid thing to do per the documentation) should that mean the new timeout X is X seconds from when event_add was called or should it be X seconds from the beginning of the current callback. If we know that then we can focus our efforts on which behavior seems broken or if this is a known change that the folks that upgraded libevent missed. -denis *********************************************************************** To unsubscribe, send an e-mail to majord...@freehaven.net with unsubscribe libevent-users in the body.
