mirror of
https://github.com/go-micro/go-micro.git
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768 lines
18 KiB
Go
768 lines
18 KiB
Go
package router
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import (
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"fmt"
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"math"
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"sort"
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"strings"
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"sync"
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"time"
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"github.com/google/uuid"
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"github.com/micro/go-micro/registry"
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"github.com/micro/go-micro/util/log"
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)
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const (
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// AdvertiseEventsTick is time interval in which the router advertises route updates
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AdvertiseEventsTick = 5 * time.Second
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// AdvertiseTableTick is time interval in which router advertises all routes found in routing table
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AdvertiseTableTick = 1 * time.Minute
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// AdvertiseFlushTick is time the yet unconsumed advertisements are flush i.e. discarded
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AdvertiseFlushTick = 15 * time.Second
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// AdvertSuppress is advert suppression threshold
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AdvertSuppress = 2000.0
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// AdvertRecover is advert recovery threshold
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AdvertRecover = 750.0
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// DefaultAdvertTTL is default advertisement TTL
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DefaultAdvertTTL = 1 * time.Minute
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// DeletePenalty penalises route deletion
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DeletePenalty = 1000.0
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// UpdatePenalty penalises route updates
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UpdatePenalty = 500.0
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// PenaltyHalfLife is the time the advert penalty decays to half its value
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PenaltyHalfLife = 2.0
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// MaxSuppressTime defines time after which the suppressed advert is deleted
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MaxSuppressTime = 5 * time.Minute
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)
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var (
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// PenaltyDecay is a coefficient which controls the speed the advert penalty decays
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PenaltyDecay = math.Log(2) / PenaltyHalfLife
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)
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// router implements default router
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type router struct {
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sync.RWMutex
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options Options
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status Status
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table *table
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exit chan struct{}
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errChan chan error
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eventChan chan *Event
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advertWg *sync.WaitGroup
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wg *sync.WaitGroup
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// advert subscribers
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subscribers map[string]chan *Advert
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}
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// newRouter creates new router and returns it
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func newRouter(opts ...Option) Router {
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// get default options
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options := DefaultOptions()
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// apply requested options
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for _, o := range opts {
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o(&options)
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}
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// set initial status to Stopped
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status := Status{Code: Stopped, Error: nil}
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return &router{
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options: options,
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status: status,
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table: newTable(),
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advertWg: &sync.WaitGroup{},
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wg: &sync.WaitGroup{},
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subscribers: make(map[string]chan *Advert),
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}
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}
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// Init initializes router with given options
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func (r *router) Init(opts ...Option) error {
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r.Lock()
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defer r.Unlock()
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for _, o := range opts {
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o(&r.options)
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}
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return nil
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}
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// Options returns router options
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func (r *router) Options() Options {
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r.Lock()
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options := r.options
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r.Unlock()
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return options
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}
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// Table returns routing table
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func (r *router) Table() Table {
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return r.table
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}
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// manageRoute applies action on a given route
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func (r *router) manageRoute(route Route, action string) error {
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switch action {
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case "create":
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if err := r.table.Create(route); err != nil && err != ErrDuplicateRoute {
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return fmt.Errorf("failed adding route for service %s: %s", route.Service, err)
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}
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case "delete":
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if err := r.table.Delete(route); err != nil && err != ErrRouteNotFound {
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return fmt.Errorf("failed deleting route for service %s: %s", route.Service, err)
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}
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case "update":
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if err := r.table.Update(route); err != nil {
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return fmt.Errorf("failed updating route for service %s: %s", route.Service, err)
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}
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case "solicit":
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// nothing to do here
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return nil
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default:
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return fmt.Errorf("failed to manage route for service %s: unknown action %s", route.Service, action)
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}
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return nil
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}
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// manageServiceRoutes applies action to all routes of the service.
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// It returns error of the action fails with error.
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func (r *router) manageServiceRoutes(service *registry.Service, action string) error {
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// action is the routing table action
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action = strings.ToLower(action)
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// take route action on each service node
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for _, node := range service.Nodes {
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route := Route{
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Service: service.Name,
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Address: node.Address,
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Gateway: "",
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Network: r.options.Network,
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Router: r.options.Id,
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Link: DefaultLink,
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Metric: DefaultLocalMetric,
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}
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if err := r.manageRoute(route, action); err != nil {
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return err
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}
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}
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return nil
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}
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// manageRegistryRoutes applies action to all routes of each service found in the registry.
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// It returns error if either the services failed to be listed or the routing table action fails.
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func (r *router) manageRegistryRoutes(reg registry.Registry, action string) error {
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services, err := reg.ListServices()
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if err != nil {
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return fmt.Errorf("failed listing services: %v", err)
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}
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// add each service node as a separate route
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for _, service := range services {
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// get the service to retrieve all its info
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srvs, err := reg.GetService(service.Name)
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if err != nil {
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continue
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}
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// manage the routes for all returned services
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for _, srv := range srvs {
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if err := r.manageServiceRoutes(srv, action); err != nil {
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return err
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}
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}
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}
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return nil
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}
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// watchRegistry watches registry and updates routing table based on the received events.
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// It returns error if either the registry watcher fails with error or if the routing table update fails.
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func (r *router) watchRegistry(w registry.Watcher) error {
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exit := make(chan bool)
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defer func() {
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// close the exit channel when the go routine finishes
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close(exit)
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r.wg.Done()
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}()
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// wait in the background for the router to stop
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// when the router stops, stop the watcher and exit
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r.wg.Add(1)
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go func() {
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defer w.Stop()
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select {
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case <-r.exit:
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return
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case <-exit:
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return
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}
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}()
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var watchErr error
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for {
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res, err := w.Next()
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if err != nil {
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if err != registry.ErrWatcherStopped {
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watchErr = err
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}
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break
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}
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if err := r.manageServiceRoutes(res.Service, res.Action); err != nil {
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return err
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}
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}
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return watchErr
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}
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// watchTable watches routing table entries and either adds or deletes locally registered service to/from network registry
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// It returns error if the locally registered services either fails to be added/deleted to/from network registry.
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func (r *router) watchTable(w Watcher) error {
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exit := make(chan bool)
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defer func() {
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// close the exit channel when the go routine finishes
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close(exit)
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r.wg.Done()
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}()
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// wait in the background for the router to stop
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// when the router stops, stop the watcher and exit
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r.wg.Add(1)
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go func() {
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defer w.Stop()
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select {
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case <-r.exit:
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return
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case <-exit:
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return
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}
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}()
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var watchErr error
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for {
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event, err := w.Next()
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if err != nil {
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if err != ErrWatcherStopped {
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watchErr = err
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}
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break
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}
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select {
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case <-r.exit:
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close(r.eventChan)
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return nil
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case r.eventChan <- event:
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}
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}
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// close event channel on error
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close(r.eventChan)
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return watchErr
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}
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// publishAdvert publishes router advert to advert channel
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// NOTE: this might cease to be a dedicated method in the future
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func (r *router) publishAdvert(advType AdvertType, events []*Event) {
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defer r.advertWg.Done()
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a := &Advert{
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Id: r.options.Id,
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Type: advType,
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TTL: DefaultAdvertTTL,
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Timestamp: time.Now(),
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Events: events,
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}
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log.Debugf("Router publishing advert; %+v", a)
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r.RLock()
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for _, sub := range r.subscribers {
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// check the exit chan first
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select {
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case <-r.exit:
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r.RUnlock()
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return
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default:
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}
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// now send the message
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select {
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case sub <- a:
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default:
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}
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}
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r.RUnlock()
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}
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// advertiseTable advertises the whole routing table to the network
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func (r *router) advertiseTable() error {
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// create table advertisement ticker
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ticker := time.NewTicker(AdvertiseTableTick)
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defer ticker.Stop()
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for {
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select {
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case <-ticker.C:
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// list routing table routes to announce
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routes, err := r.table.List()
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if err != nil {
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return fmt.Errorf("failed listing routes: %s", err)
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}
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// collect all the added routes before we attempt to add default gateway
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events := make([]*Event, len(routes))
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for i, route := range routes {
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event := &Event{
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Type: Update,
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Timestamp: time.Now(),
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Route: route,
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}
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events[i] = event
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}
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// advertise all routes as Update events to subscribers
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if len(events) > 0 {
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log.Debugf("Router flushing table with %d events: %s", len(events), r.options.Id)
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r.advertWg.Add(1)
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go r.publishAdvert(RouteUpdate, events)
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}
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case <-r.exit:
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return nil
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}
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}
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}
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// routeAdvert contains a route event to be advertised
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type routeAdvert struct {
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// event received from routing table
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event *Event
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// lastUpdate records the time of the last advert update
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lastUpdate time.Time
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// penalty is current advert penalty
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penalty float64
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// isSuppressed flags the advert suppression
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isSuppressed bool
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// suppressTime records the time interval the advert has been suppressed for
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suppressTime time.Time
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}
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// advertiseEvents advertises routing table events
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// It suppresses unhealthy flapping events and advertises healthy events upstream.
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func (r *router) advertiseEvents() error {
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// ticker to periodically scan event for advertising
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ticker := time.NewTicker(AdvertiseEventsTick)
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defer ticker.Stop()
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// advertMap is a map of advert events
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advertMap := make(map[uint64]*routeAdvert)
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// routing table watcher
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tableWatcher, err := r.Watch()
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if err != nil {
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return fmt.Errorf("failed creating routing table watcher: %v", err)
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}
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r.wg.Add(1)
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go func() {
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defer r.wg.Done()
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select {
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case r.errChan <- r.watchTable(tableWatcher):
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case <-r.exit:
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}
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}()
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for {
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select {
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case <-ticker.C:
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var events []*Event
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// collect all events which are not flapping
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for key, advert := range advertMap {
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// decay the event penalty
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delta := time.Since(advert.lastUpdate).Seconds()
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advert.penalty = advert.penalty * math.Exp(-delta*PenaltyDecay)
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// suppress/recover the event based on its penalty level
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switch {
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case advert.penalty > AdvertSuppress && !advert.isSuppressed:
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log.Debugf("Router supressing advert %d for route %s", key, advert.event.Route.Address)
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advert.isSuppressed = true
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advert.suppressTime = time.Now()
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case advert.penalty < AdvertRecover && advert.isSuppressed:
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log.Debugf("Router recovering advert %d for route %s", key, advert.event.Route.Address)
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advert.isSuppressed = false
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}
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// max suppression time threshold has been reached, delete the advert
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if advert.isSuppressed {
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if time.Since(advert.suppressTime) > MaxSuppressTime {
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delete(advertMap, key)
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continue
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}
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}
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if !advert.isSuppressed {
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e := new(Event)
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*e = *(advert.event)
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events = append(events, e)
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// delete the advert from the advertMap
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delete(advertMap, key)
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}
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}
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// advertise all Update events to subscribers
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if len(events) > 0 {
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r.advertWg.Add(1)
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log.Debugf("Router publishing %d events", len(events))
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go r.publishAdvert(RouteUpdate, events)
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}
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case e := <-r.eventChan:
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// if event is nil, continue
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if e == nil {
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continue
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}
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log.Debugf("Router processing table event %s for service %s", e.Type, e.Route.Address)
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// determine the event penalty
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var penalty float64
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switch e.Type {
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case Update:
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penalty = UpdatePenalty
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case Delete:
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penalty = DeletePenalty
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}
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// check if we have already registered the route
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hash := e.Route.Hash()
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advert, ok := advertMap[hash]
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if !ok {
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advert = &routeAdvert{
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event: e,
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penalty: penalty,
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lastUpdate: time.Now(),
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}
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advertMap[hash] = advert
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continue
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}
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// override the route event only if the last event was different
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if advert.event.Type != e.Type {
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advert.event = e
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}
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// update event penalty and timestamp
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advert.lastUpdate = time.Now()
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advert.penalty += penalty
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log.Debugf("Router advert %d for route %s event penalty: %f", hash, advert.event.Route.Address, advert.penalty)
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case <-r.exit:
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// first wait for the advertiser to finish
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r.advertWg.Wait()
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return nil
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}
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}
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}
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// close closes exit channels
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func (r *router) close() {
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// notify all goroutines to finish
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close(r.exit)
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// drain the advertise channel only if advertising
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if r.status.Code == Advertising {
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// drain the event channel
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for range r.eventChan {
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}
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// close advert subscribers
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for id, sub := range r.subscribers {
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// close the channel
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close(sub)
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// delete the subscriber
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delete(r.subscribers, id)
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}
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}
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// mark the router as Stopped and set its Error to nil
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r.status = Status{Code: Stopped, Error: nil}
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}
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// watchErrors watches router errors and takes appropriate actions
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func (r *router) watchErrors() {
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var err error
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select {
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case <-r.exit:
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return
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case err = <-r.errChan:
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}
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r.Lock()
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defer r.Unlock()
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// if the router is not stopped, stop it
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if r.status.Code != Stopped {
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// close all the channels
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r.close()
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// set the status error
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if err != nil {
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r.status.Error = err
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}
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}
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}
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// Start starts the router
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func (r *router) Start() error {
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r.Lock()
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defer r.Unlock()
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// only start if we're stopped
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if r.status.Code != Stopped {
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return nil
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}
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// add all local service routes into the routing table
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if err := r.manageRegistryRoutes(r.options.Registry, "create"); err != nil {
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e := fmt.Errorf("failed adding registry routes: %s", err)
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r.status = Status{Code: Error, Error: e}
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return e
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}
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// add default gateway into routing table
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if r.options.Gateway != "" {
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// note, the only non-default value is the gateway
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route := Route{
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Service: "*",
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Address: "*",
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Gateway: r.options.Gateway,
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Network: "*",
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Router: r.options.Id,
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Link: DefaultLink,
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Metric: DefaultLocalMetric,
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}
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if err := r.table.Create(route); err != nil {
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e := fmt.Errorf("failed adding default gateway route: %s", err)
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r.status = Status{Code: Error, Error: e}
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return e
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}
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}
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// create error and exit channels
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r.errChan = make(chan error, 1)
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r.exit = make(chan struct{})
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// registry watcher
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regWatcher, err := r.options.Registry.Watch()
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if err != nil {
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e := fmt.Errorf("failed creating registry watcher: %v", err)
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r.status = Status{Code: Error, Error: e}
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return e
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}
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r.wg.Add(1)
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go func() {
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defer r.wg.Done()
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select {
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case r.errChan <- r.watchRegistry(regWatcher):
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case <-r.exit:
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}
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}()
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// watch for errors and cleanup
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r.wg.Add(1)
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go func() {
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defer r.wg.Done()
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r.watchErrors()
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}()
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// mark router as Running
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r.status = Status{Code: Running, Error: nil}
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return nil
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}
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|
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// Advertise stars advertising the routes to the network and returns the advertisements channel to consume from.
|
|
// If the router is already advertising it returns the channel to consume from.
|
|
// It returns error if either the router is not running or if the routing table fails to list the routes to advertise.
|
|
func (r *router) Advertise() (<-chan *Advert, error) {
|
|
r.Lock()
|
|
defer r.Unlock()
|
|
|
|
switch r.status.Code {
|
|
case Advertising:
|
|
advertChan := make(chan *Advert, 128)
|
|
r.subscribers[uuid.New().String()] = advertChan
|
|
return advertChan, nil
|
|
case Running:
|
|
// list all the routes and pack them into even slice to advertise
|
|
events, err := r.flushRouteEvents(Create)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed to flush routes: %s", err)
|
|
}
|
|
|
|
// create event channels
|
|
r.eventChan = make(chan *Event)
|
|
|
|
// advertise your presence
|
|
r.advertWg.Add(1)
|
|
go r.publishAdvert(Announce, events)
|
|
|
|
r.wg.Add(1)
|
|
go func() {
|
|
defer r.wg.Done()
|
|
select {
|
|
case r.errChan <- r.advertiseEvents():
|
|
case <-r.exit:
|
|
}
|
|
}()
|
|
|
|
r.advertWg.Add(1)
|
|
go func() {
|
|
defer r.advertWg.Done()
|
|
// advertise the whole routing table
|
|
select {
|
|
case r.errChan <- r.advertiseTable():
|
|
case <-r.exit:
|
|
}
|
|
}()
|
|
|
|
// mark router as Running and set its Error to nil
|
|
r.status = Status{Code: Advertising, Error: nil}
|
|
|
|
// create advert channel
|
|
advertChan := make(chan *Advert, 128)
|
|
r.subscribers[uuid.New().String()] = advertChan
|
|
|
|
return advertChan, nil
|
|
case Stopped:
|
|
return nil, fmt.Errorf("not running")
|
|
}
|
|
|
|
return nil, fmt.Errorf("error: %s", r.status.Error)
|
|
}
|
|
|
|
// Process updates the routing table using the advertised values
|
|
func (r *router) Process(a *Advert) error {
|
|
// NOTE: event sorting might not be necessary
|
|
// copy update events intp new slices
|
|
events := make([]*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)
|
|
})
|
|
|
|
log.Debugf("Router %s processing advert from: %s", r.options.Id, a.Id)
|
|
|
|
for _, event := range events {
|
|
// skip if the router is the origin of this route
|
|
if event.Route.Router == r.options.Id {
|
|
log.Debugf("Router skipping processing its own route: %s", r.options.Id)
|
|
continue
|
|
}
|
|
// create a copy of the route
|
|
route := event.Route
|
|
action := event.Type
|
|
log.Debugf("Router %s applying %s from router %s for address: %s", r.options.Id, action, route.Router, route.Address)
|
|
if err := r.manageRoute(route, fmt.Sprintf("%s", action)); err != nil {
|
|
return fmt.Errorf("failed applying action %s to routing table: %s", action, err)
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// flushRouteEvents returns a slice of events, one per each route in the routing table
|
|
func (r *router) flushRouteEvents(evType EventType) ([]*Event, error) {
|
|
// list all routes
|
|
routes, err := r.table.List()
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed listing routes: %s", err)
|
|
}
|
|
|
|
// build a list of events to advertise
|
|
events := make([]*Event, len(routes))
|
|
for i, route := range routes {
|
|
event := &Event{
|
|
Type: evType,
|
|
Timestamp: time.Now(),
|
|
Route: route,
|
|
}
|
|
events[i] = event
|
|
}
|
|
|
|
return events, nil
|
|
}
|
|
|
|
// Solicit advertises all of its routes to the network
|
|
// It returns error if the router fails to list the routes
|
|
func (r *router) Solicit() error {
|
|
events, err := r.flushRouteEvents(Update)
|
|
if err != nil {
|
|
return fmt.Errorf("failed solicit routes: %s", err)
|
|
}
|
|
|
|
// advertise the routes
|
|
r.advertWg.Add(1)
|
|
go r.publishAdvert(RouteUpdate, events)
|
|
|
|
return nil
|
|
}
|
|
|
|
// Lookup routes in the routing table
|
|
func (r *router) Lookup(q Query) ([]Route, error) {
|
|
return r.table.Query(q)
|
|
}
|
|
|
|
// Watch routes
|
|
func (r *router) Watch(opts ...WatchOption) (Watcher, error) {
|
|
return r.table.Watch(opts...)
|
|
}
|
|
|
|
// 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 {
|
|
r.Lock()
|
|
defer r.Unlock()
|
|
|
|
switch r.status.Code {
|
|
case Stopped, Error:
|
|
return r.status.Error
|
|
case Running, Advertising:
|
|
// close all the channels
|
|
r.close()
|
|
}
|
|
|
|
// wait for all goroutines to finish
|
|
r.wg.Wait()
|
|
|
|
return nil
|
|
}
|
|
|
|
// String prints debugging information about router
|
|
func (r *router) String() string {
|
|
return "memory"
|
|
}
|