// addRelation causes the unit agent to join the supplied relation, and to
// store persistent state in the supplied dir.
func (u *Uniter) addRelation(rel *state.Relation, dir *relation.StateDir) error {
log.Printf("worker/uniter: joining relation %q", rel)
ru, err := rel.Unit(u.unit)
if err != nil {
return err
}
r := NewRelationer(ru, dir, u.relationHooks)
w := u.unit.Watch()
defer watcher.Stop(w, &u.tomb)
for {
select {
case <-u.tomb.Dying():
return tomb.ErrDying
case _, ok := <-w.Changes():
if !ok {
return watcher.MustErr(w)
}
if err := r.Join(); err == state.ErrCannotEnterScopeYet {
log.Printf("worker/uniter: cannot enter scope for relation %q; waiting for subordinate to be removed", rel)
continue
} else if err != nil {
return err
}
log.Printf("worker/uniter: joined relation %q", rel)
u.relationers[rel.Id()] = r
return nil
}
}
panic("unreachable")
}
func addRU(c *C, svc *state.Service, rel *state.Relation, principal *state.Unit) (*state.Unit, *state.RelationUnit) {
// Given the service svc in the relation rel, add a unit of svc and create
// a RelationUnit with rel. If principal is supplied, svc is assumed to be
// subordinate and the unit will be created by temporarily entering the
// relation's scope as the principal.
var u *state.Unit
if principal == nil {
unit, err := svc.AddUnit()
c.Assert(err, IsNil)
u = unit
} else {
origUnits, err := svc.AllUnits()
c.Assert(err, IsNil)
pru, err := rel.Unit(principal)
c.Assert(err, IsNil)
err = pru.EnterScope(nil) // to create the subordinate
c.Assert(err, IsNil)
err = pru.LeaveScope() // to reset to initial expected state
c.Assert(err, IsNil)
newUnits, err := svc.AllUnits()
c.Assert(err, IsNil)
for _, unit := range newUnits {
found := false
for _, old := range origUnits {
if unit.Name() == old.Name() {
found = true
break
}
}
if !found {
u = unit
break
}
}
c.Assert(u, NotNil)
}
preventUnitDestroyRemove(c, u)
ru, err := rel.Unit(u)
c.Assert(err, IsNil)
return u, ru
}