// A first-come-first-serve scheduler: acquires the first offer that can support the task
func (fps *fcfsPodScheduler) SchedulePod(r offers.Registry, task *podtask.T) (offers.Perishable, *podtask.Spec, error) {
podName := fmt.Sprintf("%s/%s", task.Pod.Namespace, task.Pod.Name)
var matchingOffer offers.Perishable
var acceptedSpec *podtask.Spec
err := r.Walk(func(p offers.Perishable) (bool, error) {
offer := p.Details()
if offer == nil {
return false, fmt.Errorf("nil offer while scheduling task %v", task.ID)
}
// check that the node actually exists. As offers are declined if not, the
// case n==nil can only happen when the node object was deleted since the
// offer came in.
nodeName := offer.GetHostname()
n := fps.lookupNode(nodeName)
if n == nil {
log.V(3).Infof("ignoring offer for node %s because node went away", nodeName)
return false, nil
}
ps := podtask.NewProcureState(offer)
err := fps.procurement.Procure(task, n, ps)
if err != nil {
log.V(5).Infof(
"Offer %q does not fit pod %s/%s: %v",
offer.Id, task.Pod.Namespace, task.Pod.Name, err,
)
return false, nil // continue
}
if !p.Acquire() {
log.V(2).Infof(
"Could not acquire offer %q for pod %s/%s",
offer.Id, task.Pod.Namespace, task.Pod.Name,
)
return false, nil // continue
}
matchingOffer = p
acceptedSpec, _ = ps.Result()
log.V(3).Infof("Pod %s accepted offer %v", podName, offer.Id.GetValue())
return true, nil // stop, we found an offer
})
if matchingOffer != nil {
if err != nil {
log.Warningf("problems walking the offer registry: %v, attempting to continue", err)
}
return matchingOffer, acceptedSpec, nil
}
if err != nil {
log.V(2).Infof("failed to find a fit for pod: %s, err = %v", podName, err)
return nil, nil, err
}
log.V(2).Infof("failed to find a fit for pod: %s", podName)
return nil, nil, errors.NoSuitableOffersErr
}
func (fps *fcfsPodScheduler) Fit(t *podtask.T, offer *mesosproto.Offer, n *api.Node) bool {
return fps.procurement.Procure(t, n, podtask.NewProcureState(offer)) == nil
}