micro/network/router/default.go

585 lines
15 KiB
Go

package router
import (
"fmt"
"math"
"sort"
"strings"
"sync"
"time"
"github.com/micro/go-log"
"github.com/micro/go-micro/network/router/table"
"github.com/micro/go-micro/registry"
"github.com/olekukonko/tablewriter"
)
const (
// AdvertiseTick is time interval in which we advertise route updates
AdvertiseTick = 5 * time.Second
// AdvertSuppress is advert suppression threshold
AdvertSuppress = 2000
// AdvertRecover is advert recovery threshold
AdvertRecover = 750
// DefaultAdvertTTL is default advertisement TTL
DefaultAdvertTTL = time.Minute
// PenaltyDecay is the penalty decay
PenaltyDecay = 1.15
// Delete penalises route addition and deletion
Delete = 1000
// UpdatePenalty penalises route updates
UpdatePenalty = 500
)
// router provides default router implementation
type router struct {
opts Options
status Status
exit chan struct{}
eventChan chan *table.Event
advertChan chan *Advert
wg *sync.WaitGroup
sync.RWMutex
}
// newRouter creates a new router and returns it
func newRouter(opts ...Option) Router {
// get default options
options := DefaultOptions()
// apply requested options
for _, o := range opts {
o(&options)
}
return &router{
opts: options,
status: Status{Error: nil, Code: Stopped},
exit: make(chan struct{}),
eventChan: make(chan *table.Event),
advertChan: make(chan *Advert),
wg: &sync.WaitGroup{},
}
}
// Init initializes router with given options
func (r *router) Init(opts ...Option) error {
for _, o := range opts {
o(&r.opts)
}
return nil
}
// Options returns router options
func (r *router) Options() Options {
return r.opts
}
// ID returns router ID
func (r *router) ID() string {
return r.opts.ID
}
// Table returns routing table
func (r *router) Table() table.Table {
return r.opts.Table
}
// Address returns router's bind address
func (r *router) Address() string {
return r.opts.Address
}
// Network returns the address router advertises to the network
func (r *router) Network() string {
return r.opts.Network
}
// manageServiceRoutes manages routes for a given service.
// It returns error of the routing table action fails.
func (r *router) manageServiceRoutes(service *registry.Service, action string, metric int) error {
// action is the routing table action
action = strings.ToLower(action)
// take route action on each service node
for _, node := range service.Nodes {
route := table.Route{
Destination: service.Name,
Gateway: node.Address,
Router: r.opts.Address,
Network: r.opts.Network,
Metric: metric,
}
switch action {
case "insert", "create":
if err := r.opts.Table.Add(route); err != nil && err != table.ErrDuplicateRoute {
return fmt.Errorf("failed adding route for service %s: %s", service.Name, err)
}
case "delete":
if err := r.opts.Table.Delete(route); err != nil && err != table.ErrRouteNotFound {
return fmt.Errorf("failed deleting route for service %v: %s", service.Name, err)
}
default:
return fmt.Errorf("failed to manage route for service %v. Unknown action: %s", service.Name, action)
}
}
return nil
}
// manageRegistryRoutes manages routes for each service found in the registry.
// It returns error if either the services failed to be listed or the routing table action fails.
func (r *router) manageRegistryRoutes(reg registry.Registry, action string, metric int) error {
services, err := reg.ListServices()
if err != nil {
return fmt.Errorf("failed listing services: %v", err)
}
// add each service node as a separate route
for _, service := range services {
// get the service to retrieve all its info
srvs, err := reg.GetService(service.Name)
if err != nil {
log.Logf("r.manageRegistryRoutes() GetService() error: %v", err)
continue
}
// manage the routes for all returned services
for _, s := range srvs {
if err := r.manageServiceRoutes(s, action, metric); err != nil {
return err
}
}
}
return nil
}
// watchServices watches services in given registry and updates the routing table accordingly.
// It returns error if the service registry watcher stops or if the routing table can't be updated.
func (r *router) watchServices(w registry.Watcher) error {
// wait in the background for the router to stop
// when the router stops, stop the watcher and exit
r.wg.Add(1)
go func() {
defer r.wg.Done()
<-r.exit
w.Stop()
}()
var watchErr error
for {
res, err := w.Next()
if err != nil {
if err != registry.ErrWatcherStopped {
watchErr = err
}
break
}
log.Logf("r.watchServices() new service event: Action: %s Service: %v", res.Action, res.Service)
if err := r.manageServiceRoutes(res.Service, res.Action, table.DefaultLocalMetric); err != nil {
return err
}
}
return watchErr
}
// watchTable watches routing table entries and either adds or deletes locally registered service to/from network registry
// It returns error if the locally registered services either fails to be added/deleted to/from network registry.
func (r *router) watchTable(w table.Watcher) error {
// wait in the background for the router to stop
// when the router stops, stop the watcher and exit
r.wg.Add(1)
go func() {
defer r.wg.Done()
<-r.exit
w.Stop()
}()
var watchErr error
for {
event, err := w.Next()
if err != nil {
if err != table.ErrWatcherStopped {
watchErr = err
}
break
}
log.Logf("r.watchTable() new table event: %s", event)
select {
case <-r.exit:
close(r.eventChan)
return nil
case r.eventChan <- event:
}
}
// close event channel on error
close(r.eventChan)
return watchErr
}
// isFlapping detects if the event is flapping based on the current and previous event status.
func isFlapping(curr, prev *table.Event) bool {
if curr.Type == table.Update && prev.Type == table.Update {
log.Logf("isFlapping(): Update flap")
return true
}
if curr.Type == table.Insert && prev.Type == table.Delete || curr.Type == table.Delete && prev.Type == table.Insert {
log.Logf("isFlapping(): Create/Delete flap")
return true
}
return false
}
// updateEvent is a table event enriched with advertisement data
type updateEvent struct {
*table.Event
// timestamp marks the time the event has been received
timestamp time.Time
// penalty is current event penalty
penalty float64
// isSuppressed flags if the event should be considered for flap detection
isSuppressed bool
// isFlapping marks the event as flapping event
isFlapping bool
}
// processEvents processes routing table events.
// It suppresses unhealthy flapping events and advertises healthy events upstream.
func (r *router) processEvents() error {
// ticker to periodically scan event for advertising
ticker := time.NewTicker(AdvertiseTick)
// eventMap is a map of advert events
eventMap := make(map[uint64]*updateEvent)
// lock to protect access to eventMap
mu := &sync.RWMutex{}
// waitgroup to manage advertisement goroutines
var wg sync.WaitGroup
processLoop:
for {
select {
case <-ticker.C:
var events []*table.Event
// collect all events which are not flapping
mu.Lock()
for key, event := range eventMap {
if !event.isFlapping && !event.isSuppressed {
e := new(table.Event)
*e = *event.Event
events = append(events, e)
// this deletes the advertised event from the map
delete(eventMap, key)
}
}
mu.Unlock()
if len(events) > 0 {
wg.Add(1)
go func(events []*table.Event) {
defer wg.Done()
log.Logf("go advertise(): start")
a := &Advert{
ID: r.ID(),
Timestamp: time.Now(),
Events: events,
}
select {
case r.advertChan <- a:
case <-r.exit:
log.Logf("go advertise(): exit")
return
}
log.Logf("go advertise(): exit")
}(events)
}
case e := <-r.eventChan:
// event timestamp
now := time.Now()
// if event is nil, continue
if e == nil {
continue
}
log.Logf("r.processEvents(): event received:\n%s", e)
// determine the event penalty
var penalty float64
switch e.Type {
case table.Update:
penalty = UpdatePenalty
case table.Delete:
penalty = Delete
}
// we use route hash as eventMap key
hash := e.Route.Hash()
event, ok := eventMap[hash]
if !ok {
event = &updateEvent{
Event: e,
penalty: penalty,
timestamp: time.Now(),
}
eventMap[hash] = event
continue
}
// update penalty for existing event: decay existing and add new penalty
delta := time.Since(event.timestamp).Seconds()
event.penalty = event.penalty*math.Exp(-delta) + penalty
event.timestamp = now
// suppress or recover the event based on its current penalty
if !event.isSuppressed && event.penalty > AdvertSuppress {
event.isSuppressed = true
} else if event.penalty < AdvertRecover {
event.isSuppressed = false
}
// if not suppressed decide if if its flapping
if !event.isSuppressed {
// detect if its flapping by comparing current and previous event
event.isFlapping = isFlapping(e, event.Event)
}
case <-r.exit:
break processLoop
}
}
// first wait for the advertiser to finish
wg.Wait()
// close the advert channel
close(r.advertChan)
log.Logf("r.processEvents(): event processor stopped")
return nil
}
// watchErrors watches router errors and takes appropriate actions
func (r *router) watchErrors(errChan <-chan error) {
defer r.wg.Done()
log.Logf("r.manage(): manage start")
var code StatusCode
var err error
select {
case <-r.exit:
code = Stopped
case err = <-errChan:
code = Error
}
log.Logf("r.watchErrors(): watchErrors exiting")
r.Lock()
defer r.Unlock()
status := Status{
Code: code,
Error: err,
}
r.status = status
// stop the router if some error happened
if err != nil && code != Stopped {
// this will stop watchers which will close r.advertChan
close(r.exit)
// drain the advertise channel
for range r.advertChan {
}
// drain the event channel
for range r.eventChan {
}
}
log.Logf("r.watchErrors(): watchErrors exit")
}
// Advertise advertises the routes to the network.
// It returns error if any of the launched goroutines fail with error.
func (r *router) Advertise() (<-chan *Advert, error) {
r.Lock()
defer r.Unlock()
if r.status.Code != Running {
// add all local service routes into the routing table
if err := r.manageRegistryRoutes(r.opts.Registry, "insert", table.DefaultLocalMetric); err != nil {
return nil, fmt.Errorf("failed adding routes: %v", err)
}
log.Logf("Routing table:\n%s", r.opts.Table)
// add default gateway into routing table
if r.opts.Gateway != "" {
// note, the only non-default value is the gateway
route := table.Route{
Destination: "*",
Gateway: r.opts.Gateway,
Router: "*",
Network: "*",
Metric: table.DefaultLocalMetric,
}
if err := r.opts.Table.Add(route); err != nil {
return nil, fmt.Errorf("failed adding default gateway route: %s", err)
}
}
// NOTE: we only need to recreate these if the router errored or was stopped
if r.status.Code == Error || r.status.Code == Stopped {
r.exit = make(chan struct{})
r.eventChan = make(chan *table.Event)
r.advertChan = make(chan *Advert)
}
// routing table watcher which watches all routes i.e. to every destination
tableWatcher, err := r.opts.Table.Watch(table.WatchDestination("*"))
if err != nil {
return nil, fmt.Errorf("failed creating routing table watcher: %v", err)
}
// service registry watcher
svcWatcher, err := r.opts.Registry.Watch()
if err != nil {
return nil, fmt.Errorf("failed creating service registry watcher: %v", err)
}
// error channel collecting goroutine errors
errChan := make(chan error, 3)
r.wg.Add(1)
go func() {
defer r.wg.Done()
log.Logf("r.Advertise(): r.watchServices() start")
// watch local registry and register routes in routine table
errChan <- r.watchServices(svcWatcher)
log.Logf("r.Advertise(): r.watchServices() exit")
}()
r.wg.Add(1)
go func() {
defer r.wg.Done()
log.Logf("r.Advertise(): r.watchTable() start")
// watch local registry and register routes in routing table
errChan <- r.watchTable(tableWatcher)
log.Logf("r.Advertise(): r.watchTable() exit")
}()
r.wg.Add(1)
go func() {
defer r.wg.Done()
log.Logf("r.Advertise(): r.processEvents() start")
// listen to routing table events and process them
errChan <- r.processEvents()
log.Logf("r.Advertise(): r.processEvents() exit")
}()
r.wg.Add(1)
go r.watchErrors(errChan)
// TODO: send router announcement update comes here
// the announcement update contains routes from routing table
// mark router as running and set its Error to nil
status := Status{
Code: Running,
Error: nil,
}
r.status = status
}
return r.advertChan, nil
}
// Update updates the routing table using the advertised values
func (r *router) Update(a *Advert) error {
// NOTE: event sorting might not be necessary
// copy update events intp new slices
events := make([]*table.Event, len(a.Events))
copy(events, a.Events)
// sort events by timestamp
sort.Slice(events, func(i, j int) bool {
return events[i].Timestamp.Before(events[j].Timestamp)
})
for _, event := range events {
// we extract the route from advertisement and update the routing table
route := table.Route{
Destination: event.Route.Destination,
Gateway: event.Route.Gateway,
Router: event.Route.Router,
Network: event.Route.Network,
Metric: event.Route.Metric,
}
if err := r.opts.Table.Update(route); err != nil {
return fmt.Errorf("failed updating routing table: %v", err)
}
}
return nil
}
// Status returns router status
func (r *router) Status() Status {
r.RLock()
defer r.RUnlock()
// make a copy of the status
status := r.status
return status
}
// Stop stops the router
func (r *router) Stop() error {
log.Logf("r.Stop(): Stopping router")
r.RLock()
// only close the channel if the router is running
if r.status.Code == Running {
// notify all goroutines to finish
close(r.exit)
log.Logf("r.Stop(): exit closed")
// drain the advertise channel
for range r.advertChan {
}
log.Logf("r.Stop(): advert channel drained")
// drain the event channel
for range r.eventChan {
}
log.Logf("r.Stop(): event channel drained")
}
r.RUnlock()
// wait for all goroutines to finish
r.wg.Wait()
log.Logf("r.Stop(): Router stopped")
return nil
}
// String prints debugging information about router
func (r *router) String() string {
sb := &strings.Builder{}
table := tablewriter.NewWriter(sb)
table.SetHeader([]string{"ID", "Address", "Network", "Table", "Status"})
data := []string{
r.opts.ID,
r.opts.Address,
r.opts.Network,
fmt.Sprintf("%d", r.opts.Table.Size()),
r.status.Code.String(),
}
table.Append(data)
// render table into sb
table.Render()
return sb.String()
}