| 2012-08-03 10:00:38 |
William Reade |
description |
The first client that desperately needs lifecycles to work is the unit agent, which needs to track relation lifecycle. I hope I'm not going to regret this, but I *think* that all I need is a ServiceRelationsWatcher that produces these:
type RelationsChange struct {
Changed []*Relation
}
The initial event should contain every relation, whatever its state; subsequent ones should contain only the relations whose state has changed since the last event. I have come to the conclusion that I actually don't need separate Alive/Dying/Dead fields in the event.
(Relation needs Life and SetLife, or whatever it was we agreed on.) |
The first client that desperately needs lifecycles to work is the unit agent, which needs to track relation lifecycle. I hope I'm not going to regret this, but I *think* that all I need is a ServiceRelationsWatcher that watches a specific service's relations throughout their lifecycle and produces these:
type RelationsChange struct {
Changed []*Relation
}
The initial event should contain every relation, whatever its state; subsequent ones should contain only the relations whose state has changed since the last event. I have come to the conclusion that I actually don't need separate Alive/Dying/Dead fields in the event.
AIUI, it will need to:
* watch the topology for changes to the service's relations as it currently does
* on relevant topology change:
* for each added relation:
* store its life status, and start a life watch *unless* it is already dead
* report all added relations in a single event
* on life change (that was started on new topology relation)
* if life status is Dead, stop the relation's life watch
* report the single changed relation in a single event
In my mind, this kinda assumes a LifeWatcher type that guarantees it won't send the same status more than once, but guarantees it *will* send a Dead event if the node is deleted before it notices a change to Dead.
(Relation needs Life and SetLife, or whatever it was we agreed on.) |
|
