// execute some action in the deferred context of the process, but only if we
// match the stage of the process at the time the action is executed.
func (stage stageType) Do(p *SchedulerProcess, a proc.Action) <-chan error {
errOnce := proc.NewErrorOnce(p.fin)
errOuter := p.Do(proc.Action(func() {
switch stage {
case standbyStage:
//await standby signal or death
select {
case <-p.standby:
case <-p.Done():
}
case masterStage:
//await elected signal or death
select {
case <-p.elected:
case <-p.Done():
}
case finStage:
errOnce.Reportf("scheduler process is dying, dropping action")
return
default:
}
errOnce.Report(stage.When(p, a))
}))
return errOnce.Send(errOuter).Err()
}
func newReconciler(doer proc.Doer, action ReconcilerAction,
cooldown, explicitReconciliationAbortTimeout time.Duration, done <-chan struct{}) *Reconciler {
return &Reconciler{
Doer: doer,
explicit: make(chan struct{}, 1),
implicit: make(chan struct{}, 1),
cooldown: cooldown,
explicitReconciliationAbortTimeout: explicitReconciliationAbortTimeout,
done: done,
Action: func(driver bindings.SchedulerDriver, cancel <-chan struct{}) <-chan error {
// trigged the reconciler action in the doer's execution context,
// but it could take a while and the scheduler needs to be able to
// process updates, the callbacks for which ALSO execute in the SAME
// deferred execution context -- so the action MUST be executed async.
errOnce := proc.NewErrorOnce(cancel)
return errOnce.Send(doer.Do(func() {
// only triggers the action if we're the currently elected,
// registered master and runs the action async.
go func() {
var err <-chan error
defer errOnce.Send(err)
err = action(driver, cancel)
}()
})).Err()
},
}
}
// New creates a new KubernetesScheduler
func New(config Config) *KubernetesScheduler {
var k *KubernetesScheduler
k = &KubernetesScheduler{
schedcfg: &config.Schedcfg,
RWMutex: new(sync.RWMutex),
executor: config.Executor,
executorGroup: uid.Parse(config.Executor.ExecutorId.GetValue()).Group(),
PodScheduler: config.Scheduler,
client: config.Client,
etcdClient: config.EtcdClient,
failoverTimeout: config.FailoverTimeout,
reconcileInterval: config.ReconcileInterval,
offers: offers.CreateRegistry(offers.RegistryConfig{
Compat: func(o *mesos.Offer) bool {
// filter the offers: the executor IDs must not identify a kubelet-
// executor with a group that doesn't match ours
for _, eid := range o.GetExecutorIds() {
execuid := uid.Parse(eid.GetValue())
if execuid.Name() == execcfg.DefaultInfoID && execuid.Group() != k.executorGroup {
return false
}
}
return true
},
DeclineOffer: func(id string) <-chan error {
errOnce := proc.NewErrorOnce(k.terminate)
errOuter := k.asRegisteredMaster.Do(func() {
var err error
defer errOnce.Report(err)
offerId := mutil.NewOfferID(id)
filters := &mesos.Filters{}
_, err = k.driver.DeclineOffer(offerId, filters)
})
return errOnce.Send(errOuter).Err()
},
// remember expired offers so that we can tell if a previously scheduler offer relies on one
LingerTTL: config.Schedcfg.OfferLingerTTL.Duration,
TTL: config.Schedcfg.OfferTTL.Duration,
ListenerDelay: config.Schedcfg.ListenerDelay.Duration,
}),
slaveHostNames: slave.NewRegistry(),
taskRegistry: podtask.NewInMemoryRegistry(),
reconcileCooldown: config.ReconcileCooldown,
registration: make(chan struct{}),
asRegisteredMaster: proc.DoerFunc(func(proc.Action) <-chan error {
return proc.ErrorChanf("cannot execute action with unregistered scheduler")
}),
}
return k
}
func (self *SchedulerProcess) Elect(newDriver DriverFactory) {
errOnce := proc.NewErrorOnce(self.fin)
proc.OnError(errOnce.Send(standbyStage.Do(self, proc.Action(func() {
if !(&self.stage).transition(standbyStage, masterStage) {
log.Errorf("failed to transition from standby to master stage, aborting")
self.End()
return
}
log.Infoln("scheduler process entered master stage")
drv, err := newDriver()
if err != nil {
log.Errorf("failed to fetch scheduler driver: %v", err)
self.End()
return
}
log.V(1).Infoln("starting driver...")
stat, err := drv.Start()
if stat == mesos.Status_DRIVER_RUNNING && err == nil {
log.Infoln("driver started successfully and is running")
close(self.elected)
go func() {
defer self.End()
_, err := drv.Join()
if err != nil {
log.Errorf("driver failed with error: %v", err)
}
errOnce.Report(err)
}()
return
}
defer self.End()
if err != nil {
log.Errorf("failed to start scheduler driver: %v", err)
} else {
log.Errorf("expected RUNNING status, not %v", stat)
}
}))).Err(), func(err error) {
defer self.End()
log.Errorf("failed to handle election event, aborting: %v", err)
}, self.fin)
}
// execute task reconciliation, returns when r.done is closed. intended to run as a goroutine.
// if reconciliation is requested while another is in progress, the in-progress operation will be
// cancelled before the new reconciliation operation begins.
func (r *Reconciler) Run(driver bindings.SchedulerDriver) {
var cancel, finished chan struct{}
requestLoop:
for {
select {
case <-r.done:
return
default: // proceed
}
select {
case <-r.implicit:
metrics.ReconciliationRequested.WithLabelValues("implicit").Inc()
select {
case <-r.done:
return
case <-r.explicit:
break // give preference to a pending request for explicit
default: // continue
// don't run implicit reconciliation while explicit is ongoing
if finished != nil {
select {
case <-finished: // continue w/ implicit
default:
log.Infoln("skipping implicit reconcile because explicit reconcile is ongoing")
continue requestLoop
}
}
errOnce := proc.NewErrorOnce(r.done)
errCh := r.Do(func() {
var err error
defer errOnce.Report(err)
log.Infoln("implicit reconcile tasks")
metrics.ReconciliationExecuted.WithLabelValues("implicit").Inc()
if _, err = driver.ReconcileTasks([]*mesos.TaskStatus{}); err != nil {
log.V(1).Infof("failed to request implicit reconciliation from mesos: %v", err)
}
})
proc.OnError(errOnce.Send(errCh).Err(), func(err error) {
log.Errorf("failed to run implicit reconciliation: %v", err)
}, r.done)
goto slowdown
}
case <-r.done:
return
case <-r.explicit: // continue
metrics.ReconciliationRequested.WithLabelValues("explicit").Inc()
}
if cancel != nil {
close(cancel)
cancel = nil
// play nice and wait for the prior operation to finish, complain
// if it doesn't
select {
case <-r.done:
return
case <-finished: // noop, expected
case <-time.After(r.explicitReconciliationAbortTimeout): // very unexpected
log.Error("reconciler action failed to stop upon cancellation")
}
}
// copy 'finished' to 'fin' here in case we end up with simultaneous go-routines,
// if cancellation takes too long or fails - we don't want to close the same chan
// more than once
cancel = make(chan struct{})
finished = make(chan struct{})
go func(fin chan struct{}) {
startedAt := time.Now()
defer func() {
metrics.ReconciliationLatency.Observe(metrics.InMicroseconds(time.Since(startedAt)))
}()
metrics.ReconciliationExecuted.WithLabelValues("explicit").Inc()
defer close(fin)
err := <-r.Action(driver, cancel)
if err == reconciliationCancelledErr {
metrics.ReconciliationCancelled.WithLabelValues("explicit").Inc()
log.Infoln(err.Error())
} else if err != nil {
log.Errorf("reconciler action failed: %v", err)
}
}(finished)
slowdown:
// don't allow reconciliation to run very frequently, either explicit or implicit
select {
case <-r.done:
return
case <-time.After(r.cooldown): // noop
}
} // for
}