Golang proc.NewErrorOnce函數代碼示例

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()
		},
	}
}

// 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()
}

// 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,
		nodeRegistrator:   node.NewRegistrator(config.Client, config.LookupNode),
		offers: offers.CreateRegistry(offers.RegistryConfig{
			Compat: func(o *mesos.Offer) bool {
				// the node must be registered and have up-to-date labels
				n := config.LookupNode(o.GetHostname())
				if n == nil || !node.IsUpToDate(n, node.SlaveAttributesToLabels(o.GetAttributes())) {
					return false
				}

				// 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
}

// New creates a new Framework
func New(config Config) Framework {
	var k *framework
	k = &framework{
		schedulerConfig:   &config.SchedulerConfig,
		RWMutex:           new(sync.RWMutex),
		client:            config.Client,
		failoverTimeout:   config.FailoverTimeout,
		reconcileInterval: config.ReconcileInterval,
		nodeRegistrator:   node.NewRegistrator(config.Client, config.LookupNode),
		executorId:        config.ExecutorId,
		offers: offers.CreateRegistry(offers.RegistryConfig{
			Compat: func(o *mesos.Offer) bool {
				// the node must be registered and have up-to-date labels
				n := config.LookupNode(o.GetHostname())
				if n == nil || !node.IsUpToDate(n, node.SlaveAttributesToLabels(o.GetAttributes())) {
					return false
				}

				eids := len(o.GetExecutorIds())
				switch {
				case eids > 1:
					// at most one executor id expected. More than one means that
					// the given node is seriously in trouble.
					return false

				case eids == 1:
					// the executor id must match, otherwise the running executor
					// is incompatible with the current scheduler configuration.
					if eid := o.GetExecutorIds()[0]; eid.GetValue() != config.ExecutorId.GetValue() {
						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.SchedulerConfig.OfferLingerTTL.Duration,
			TTL:           config.SchedulerConfig.OfferTTL.Duration,
			ListenerDelay: config.SchedulerConfig.ListenerDelay.Duration,
		}),
		slaveHostNames:    newSlaveRegistry(),
		reconcileCooldown: config.ReconcileCooldown,
		registration:      make(chan struct{}),
		asRegisteredMaster: proc.DoerFunc(func(proc.Action) <-chan error {
			return proc.ErrorChanf("cannot execute action with unregistered scheduler")
		}),
		storeFrameworkId: config.StoreFrameworkId,
		lookupNode:       config.LookupNode,
	}
	return k
}