Golang Service.Instances方法代碼示例

// sync synchronizes the number of running instances for this service
func (l *ServiceListener) sync(svc *service.Service, rss []dao.RunningService) bool {
	// sort running services by instance ID, so that you stop instances by the
	// lowest instance ID first and start instances with the greatest instance
	// ID last.
	sort.Sort(instances(rss))

	// resume any paused running services
	for _, state := range rss {
		// resumeInstance updates the service state ONLY if it has a PAUSED DesiredState
		if err := resumeInstance(l.conn, state.HostID, state.ID); err != nil {
			glog.Warningf("Could not resume paused service instance %s (%s) for service %s on host %s: %s", state.ID, state.Name, state.ServiceID, state.HostID, err)
		}
	}

	// if the service has a change option for restart all on changed, stop all
	// instances and wait for the nodes to stop.  Once all service instances
	// have been stopped (deleted), then go ahead and start the instances back
	// up.
	if count := len(rss); count > 0 && count != svc.Instances && utils.StringInSlice("restartAllOnInstanceChanged", svc.ChangeOptions) {
		svc.Instances = 0 // NOTE: this will not update the node in zk or elastic
	}

	// netInstances is the difference between the number of instances that
	// should be running, as described by the service from the number of
	// instances that are currently running
	netInstances := svc.Instances - len(rss)

	if netInstances > 0 {
		// If the service lock is enabled, do not try to start any service instances
		// This will prevent the retry restart from activating
		if locked, err := IsServiceLocked(l.conn); err != nil {
			glog.Errorf("Could not check service lock: %s", err)
			return true
		} else if locked {
			glog.Warningf("Could not start %d instances; service %s (%s) is locked", netInstances, svc.Name, svc.ID)
			return true
		}

		// the number of running instances is *less* than the number of
		// instances that need to be running, so schedule instances to start
		glog.V(2).Infof("Starting %d instances of service %s (%s)", netInstances, svc.Name, svc.ID)
		var (
			last        = 0
			instanceIDs = make([]int, netInstances)
		)

		// Find which instances IDs are being unused and add those instances
		// first.  All SERVICES must have an instance ID of 0, if instance ID
		// zero dies for whatever reason, then the service must schedule
		// another 0-id instance to take its place.
		j := 0
		for i := range instanceIDs {
			for j < len(rss) && last == rss[j].InstanceID {
				// if instance ID exists, then keep searching the list for
				// the next unique instance ID
				last += 1
				j += 1
			}
			instanceIDs[i] = last
			last += 1
		}

		return netInstances == l.start(svc, instanceIDs)
	} else if netInstances = -netInstances; netInstances > 0 {
		// the number of running instances is *greater* than the number of
		// instances that need to be running, so schedule instances to stop of
		// the highest instance IDs.
		glog.V(2).Infof("Stopping %d of %d instances of service %s (%s)", netInstances, len(rss), svc.Name, svc.ID)
		l.stop(rss[svc.Instances:])
	}

	return true
}