func()

in agent/acs/update_handler/updater.go [88:164]
63 lines of code
9 McCabe index (conditional complexity)

func (u *updater) stageUpdateHandler() func(req *ecsacs.StageUpdateMessage) {
	return func(req *ecsacs.StageUpdateMessage) {
		u.Lock()
		defer u.Unlock()

		if req == nil || req.MessageId == nil {
			seelog.Error("Nil request to stage update or missing MessageID")
			return
		}

		nack := func(reason string) {
			seelog.Errorf("Nacking StageUpdate; reason: %s", reason)
			u.acs.MakeRequest(&ecsacs.NackRequest{
				Cluster:           req.ClusterArn,
				ContainerInstance: req.ContainerInstanceArn,
				MessageId:         req.MessageId,
				Reason:            aws.String(reason),
			})
			u.reset()
		}

		if !u.config.UpdatesEnabled.Enabled() {
			nack("Updates are disabled")
			return
		}

		if err := validateUpdateInfo(req.UpdateInfo); err != nil {
			nack("Invalid update: " + err.Error())
			return
		}

		seelog.Debug("Staging update", "update", req)

		if u.stage != updateNone {
			if u.updateID != "" && u.updateID == *req.UpdateInfo.Signature {
				seelog.Debug("Update already in progress, acking duplicate message", "id", u.updateID)
				// Acking here is safe as any currently-downloading update will already be holding
				// the update lock.  A failed download will nack and clear state (while holding the
				// update lock) before this code is reached, meaning that the above conditional will
				// not evaluate true (no matching, in-progress update).
				u.acs.MakeRequest(&ecsacs.AckRequest{
					Cluster:           req.ClusterArn,
					ContainerInstance: req.ContainerInstanceArn,
					MessageId:         req.MessageId,
				})
				return
			} else {
				// Nack previous update
				reason := "New update arrived: " + *req.MessageId
				u.acs.MakeRequest(&ecsacs.NackRequest{
					Cluster:           req.ClusterArn,
					ContainerInstance: req.ContainerInstanceArn,
					MessageId:         &u.downloadMessageID,
					Reason:            &reason,
				})
			}
		}
		u.updateID = *req.UpdateInfo.Signature
		u.stage = updateDownloading
		u.stageTime = ttime.Now()
		u.downloadMessageID = *req.MessageId

		err := u.download(req.UpdateInfo)
		if err != nil {
			nack("Unable to download: " + err.Error())
			return
		}

		u.stage = updateDownloaded

		u.acs.MakeRequest(&ecsacs.AckRequest{
			Cluster:           req.ClusterArn,
			ContainerInstance: req.ContainerInstanceArn,
			MessageId:         req.MessageId,
		})
	}
}