[Performance] Avoid looping and removing an AtmosphereResource from all available Broadcasters

[jfarcand]

When an AtmosphereResource gets destroyed because of a disconnect, we always loops in search for reference to all Broadcaster in DefaultBroadcasterFactory

    @Override
    public void removeAllAtmosphereResource(AtmosphereResource r) {
        // Remove inside all Broadcaster as well.
        try {
            if (store.size() > 0) {
                for (Broadcaster b : lookupAll()) {
                    try {
                        b.removeAtmosphereResource(r);
                    } catch (IllegalStateException ex) {
                        logger.trace(ex.getMessage(), ex);
                    }
                }
            }
        } catch (Exception ex) {
            logger.warn(ex.getMessage(), ex);
        }
    }

When there are thousand of Broadcaster created, this creates a performance botteneck. It would be better to associate a list of Broadcaster to an AtmosphereResource in that case, and make sure when a Broadcaster is destroyed it is also removed from that list.

[thabach]

👍