After talking with Brian, we're pretty sure that this is only because
really, really old libevent didn't allow bitwise or-ing of the other
loop types, because what we really need is (EVLOOP_ONCE |
EVLOOP_NONBLOCK). And that's what EVLOOP_ONELOOP did (i.e., we
changed the logic of libevent's event.c to let ONELOOP do both ONCE
and NONBLOCK things).
In the new libevent version, we didn't implement EVLOOP_ONELOOP
properly. As a result, and we got hangs in the SM BTL add_procs
function. Note that the SM BTL wasn't to blame -- it was purely a
side-effect of bad ONELOOP integration (i.e., if you got past the SM
BTL add_procs, you may well have hung somewhere else).
This commit removes all ONELOOP customizations from event.c and
returns it to (almost) its original state from the libevent 2.0.7-rc
distribution. Everwhere in the code base where we used ONELOOP, we
now use (ONCE | NONBLOCK).
This commit was SVN r23957.
This is a fairly intrusive change, but outside of the moving of opal/event to opal/mca/event, the only changes involved (a) changing all calls to opal_event functions to reflect the new framework instead, and (b) ensuring that all opal_event_t objects are properly constructed since they are now true opal_objects.
Note: Shiqing has just returned from vacation and has not yet had a chance to complete the Windows integration. Thus, this commit almost certainly breaks Windows support on the trunk. However, I want this to have a chance to soak for as long as possible before I become less available a week from today (going to be at a class for 5 days, and thus will only be sparingly available) so we can find and fix any problems.
Biggest change is moving the libevent code from opal/event to a new opal/mca/event framework. This was done to make it much easier to update libevent in the future. New versions can be inserted as a new component and tested in parallel with the current version until validated, then we can remove the earlier version if we so choose. This is a statically built framework ala installdirs, so only one component will build at a time. There is no selection logic - the sole compiled component simply loads its function pointers into the opal_event struct.
I have gone thru the code base and converted all the libevent calls I could find. However, I cannot compile nor test every environment. It is therefore quite likely that errors remain in the system. Please keep an eye open for two things:
1. compile-time errors: these will be obvious as calls to the old functions (e.g., opal_evtimer_new) must be replaced by the new framework APIs (e.g., opal_event.evtimer_new)
2. run-time errors: these will likely show up as segfaults due to missing constructors on opal_event_t objects. It appears that it became a typical practice for people to "init" an opal_event_t by simply using memset to zero it out. This will no longer work - you must either OBJ_NEW or OBJ_CONSTRUCT an opal_event_t. I tried to catch these cases, but may have missed some. Believe me, you'll know when you hit it.
There is also the issue of the new libevent "no recursion" behavior. As I described on a recent email, we will have to discuss this and figure out what, if anything, we need to do.
This commit was SVN r23925.
