Changed router interface. Added table watcher. Advertise routes

* Changed router interface to return Advertisement channel
* Added default gateway route to the routing table if supplied
* Watch table for updates and advertise to the network
* We hash the routes on 3-tuple (Destination, Gateway, Network)
This commit is contained in:
Milos Gajdos 2019-06-27 22:52:51 +01:00
parent 0971deb9cc
commit 9d7420658d
No known key found for this signature in database
GPG Key ID: 8B31058CC55DFD4F
6 changed files with 172 additions and 42 deletions

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@ -11,16 +11,15 @@ import (
// router provides default router implementation // router provides default router implementation
type router struct { type router struct {
opts Options opts Options
exit chan struct{} started bool
wg *sync.WaitGroup advertChan chan *Advertisement
exit chan struct{}
wg *sync.WaitGroup
} }
// newRouter creates new router and returns it // newRouter creates new router and returns it
func newRouter(opts ...Option) Router { func newRouter(opts ...Option) Router {
// TODO: we need to add default GW entry here
// Should default GW be part of router options?
// get default options // get default options
options := DefaultOptions() options := DefaultOptions()
@ -30,9 +29,11 @@ func newRouter(opts ...Option) Router {
} }
return &router{ return &router{
opts: options, opts: options,
exit: make(chan struct{}), started: false,
wg: &sync.WaitGroup{}, advertChan: make(chan *Advertisement),
exit: make(chan struct{}),
wg: &sync.WaitGroup{},
} }
} }
@ -69,43 +70,106 @@ func (r *router) Network() string {
return r.opts.Network return r.opts.Network
} }
// Advertise advertises the routes to the network. It is a blocking function. // Advertise advertises the routes to the network.
// It returns error if any of the launched goroutines fail with error. // It returns error if any of the launched goroutines fail with error.
func (r *router) Advertise() error { func (r *router) Advertise() (<-chan *Advertisement, error) {
// add local service routes into the routing table if !r.started {
if err := r.addServiceRoutes(r.opts.Registry, "local", DefaultLocalMetric); err != nil { // add local service routes into the routing table
return fmt.Errorf("failed adding routes: %v", err) if err := r.addServiceRoutes(r.opts.Registry, "local", DefaultLocalMetric); err != nil {
return nil, fmt.Errorf("failed adding routes: %v", err)
}
// add default gateway into routing table
if r.opts.Gateway != "" {
// note, the only non-default value is the gateway
route := Route{
Destination: "*",
Gateway: r.opts.Gateway,
Router: "*",
Network: "*",
Metric: DefaultLocalMetric,
}
if err := r.opts.Table.Add(route); err != nil {
return nil, fmt.Errorf("error adding default gateway route: %s", err)
}
}
// routing table watcher that watches all routes being added
tableWatcher, err := r.opts.Table.Watch(WatchDestination("*"))
if err != nil {
return nil, fmt.Errorf("failed to create routing table watcher: %v", err)
}
// registry watcher
regWatcher, err := r.opts.Registry.Watch()
if err != nil {
return nil, fmt.Errorf("failed to create registry watcher: %v", err)
}
// error channel collecting goroutine errors
errChan := make(chan error, 2)
r.wg.Add(1)
go func() {
defer r.wg.Done()
// watch local registry and register routes in routine table
errChan <- r.manageServiceRoutes(regWatcher, DefaultLocalMetric)
}()
r.wg.Add(1)
go func() {
defer r.wg.Done()
// watch local registry and register routes in routine table
errChan <- r.watchTable(tableWatcher)
}()
go func() {
select {
// wait for exit chan
case <-r.exit:
// wait for error
case <-errChan:
// TODO: we're missing the error context here
// might have to log it here as we don't send it down
}
// close the advertise channel
close(r.advertChan)
}()
// mark the router as started
r.started = true
} }
localWatcher, err := r.opts.Registry.Watch() return r.advertChan, nil
if err != nil { }
return fmt.Errorf("failed to create registry watcher: %v", err)
// Update updates the routing table using the advertised values
func (r *router) Update(a *Advertisement) error {
// we extract the route from advertisement and update the routing table
route := Route{
Destination: a.Event.Route.Destination,
Gateway: a.Event.Route.Gateway,
Router: a.Event.Route.Router,
Network: a.Event.Route.Network,
Metric: a.Event.Route.Metric,
Policy: AddIfNotExists,
} }
// error channel collecting goroutine errors return r.opts.Table.Update(route)
errChan := make(chan error, 1)
r.wg.Add(1)
go func() {
defer r.wg.Done()
// watch local registry and register routes in routine table
errChan <- r.manageServiceRoutes(localWatcher, DefaultLocalMetric)
}()
return <-errChan
} }
// addServiceRoutes adds all services in given registry to the routing table. // addServiceRoutes adds all services in given registry to the routing table.
// NOTE: this is a one-off operation done when bootstrapping the routing table // NOTE: this is a one-off operation done when bootstrapping the routing table
// It returns error if either the services failed to be listed or // It returns error if either the services failed to be listed or
// if the routes could not be added to the routing table. // if any of the the routes could not be added to the routing table.
func (r *router) addServiceRoutes(reg registry.Registry, network string, metric int) error { func (r *router) addServiceRoutes(reg registry.Registry, network string, metric int) error {
services, err := reg.ListServices() services, err := reg.ListServices()
if err != nil { if err != nil {
return fmt.Errorf("failed to list services: %v", err) return fmt.Errorf("failed to list services: %v", err)
} }
// add each service node as a separate route; // add each service node as a separate route
for _, service := range services { for _, service := range services {
// get the service to retrieve all its info // get the service to retrieve all its info
srvs, err := reg.GetService(service.Name) srvs, err := reg.GetService(service.Name)
@ -190,6 +254,40 @@ func (r *router) manageServiceRoutes(w registry.Watcher, metric int) error {
return watchErr 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 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 == ErrWatcherStopped {
break
}
if err != nil {
watchErr = err
break
}
r.advertChan <- &Advertisement{
ID: r.ID(),
Event: event,
}
}
return watchErr
}
// Stop stops the router // Stop stops the router
func (r *router) Stop() error { func (r *router) Stop() error {
// notify all goroutines to finish // notify all goroutines to finish

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@ -129,6 +129,12 @@ func (t *table) Update(r Route) error {
// check if the destAddr has ANY routes in the table // check if the destAddr has ANY routes in the table
if _, ok := t.m[destAddr]; !ok { if _, ok := t.m[destAddr]; !ok {
if r.Policy == AddIfNotExists {
t.m[destAddr] = make(map[uint64]Route)
t.m[destAddr][sum] = r
go t.sendEvent(&Event{Type: CreateEvent, Route: r})
return nil
}
return ErrRouteNotFound return ErrRouteNotFound
} }
@ -279,7 +285,7 @@ func (t *table) String() string {
// hash hashes the route using router gateway and network address // hash hashes the route using router gateway and network address
func (t *table) hash(r Route) uint64 { func (t *table) hash(r Route) uint64 {
t.h.Reset() t.h.Reset()
t.h.Write([]byte(r.Destination + r.Gateway + r.Router + r.Network)) t.h.Write([]byte(r.Destination + r.Gateway + r.Network))
return t.h.Sum64() return t.h.Sum64()
} }

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@ -8,6 +8,8 @@ import (
var ( var (
// DefaultAddress is default router address // DefaultAddress is default router address
DefaultAddress = ":9093" DefaultAddress = ":9093"
// DefaultNetwork is default micro network
DefaultNetwork = "local"
) )
// Options are router options // Options are router options
@ -18,6 +20,8 @@ type Options struct {
Address string Address string
// Network is micro network // Network is micro network
Network string Network string
// Gateway is micro network gateway
Gateway string
// Registry is the local registry // Registry is the local registry
Registry registry.Registry Registry registry.Registry
// Table is routing table // Table is routing table
@ -45,6 +49,13 @@ func Network(n string) Option {
} }
} }
// Gateway sets network gateway
func Gateway(g string) Option {
return func(o *Options) {
o.Gateway = g
}
}
// RoutingTable sets the routing table // RoutingTable sets the routing table
func RoutingTable(t Table) Option { func RoutingTable(t Table) Option {
return func(o *Options) { return func(o *Options) {
@ -61,12 +72,11 @@ func Registry(r registry.Registry) Option {
// DefaultOptions returns router default options // DefaultOptions returns router default options
func DefaultOptions() Options { func DefaultOptions() Options {
// NOTE: by default both local and network registies use default registry i.e. mdns
return Options{ return Options{
ID: uuid.New().String(), ID: uuid.New().String(),
Address: DefaultAddress, Address: DefaultAddress,
Network: DefaultNetwork,
Registry: registry.DefaultRegistry, Registry: registry.DefaultRegistry,
Table: NewTable(), Table: NewTable(),
Network: "local",
} }
} }

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@ -20,6 +20,8 @@ type RoutePolicy int
const ( const (
// OverrideIfExists overrides route if it already exists // OverrideIfExists overrides route if it already exists
OverrideIfExists RoutePolicy = iota OverrideIfExists RoutePolicy = iota
// AddIfNotExist adds the route if it does not exist
AddIfNotExists
// IgnoreIfExists instructs to not modify existing route // IgnoreIfExists instructs to not modify existing route
IgnoreIfExists IgnoreIfExists
) )
@ -28,9 +30,11 @@ const (
func (p RoutePolicy) String() string { func (p RoutePolicy) String() string {
switch p { switch p {
case OverrideIfExists: case OverrideIfExists:
return "OVERRIDE" return "OVERRIDE_IF_EXISTS"
case AddIfNotExists:
return "ADD_IF_NOT_EXISTS"
case IgnoreIfExists: case IgnoreIfExists:
return "IGNORE" return "IGNORE_IF_EXISTS"
default: default:
return "UNKNOWN" return "UNKNOWN"
} }

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@ -1,6 +1,11 @@
// Package router provides a network routing control plane // Package router provides a network routing control plane
package router package router
var (
// DefaultRouter is default network router
DefaultRouter = NewRouter()
)
// Router is an interface for a routing control plane // Router is an interface for a routing control plane
type Router interface { type Router interface {
// Init initializes the router with options // Init initializes the router with options
@ -15,21 +20,27 @@ type Router interface {
Address() string Address() string
// Network returns the network address of the router // Network returns the network address of the router
Network() string Network() string
// Advertise starts advertising the routes to the network // Advertise starts advertising routes to the network
Advertise() error Advertise() (<-chan *Advertisement, error)
// Update updates the routing table
Update(*Advertisement) error
// Stop stops the router // Stop stops the router
Stop() error Stop() error
// String returns debug info // String returns debug info
String() string String() string
} }
// Advertisement is sent by the router to the network
type Advertisement struct {
// ID is the source router ID
ID string
// Event defines advertisement even
Event *Event
}
// Option used by the router // Option used by the router
type Option func(*Options) type Option func(*Options)
var (
DefaultRouter = NewRouter()
)
// NewRouter creates new Router and returns it // NewRouter creates new Router and returns it
func NewRouter(opts ...Option) Router { func NewRouter(opts ...Option) Router {
return newRouter(opts...) return newRouter(opts...)

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@ -81,7 +81,7 @@ type tableWatcher struct {
} }
// Next returns the next noticed action taken on table // Next returns the next noticed action taken on table
// TODO: this needs to be thought through properly; we only allow watching particular route destination // TODO: this needs to be thought through properly; we only allow watching particular route destination for now
func (w *tableWatcher) Next() (*Event, error) { func (w *tableWatcher) Next() (*Event, error) {
for { for {
select { select {
@ -93,6 +93,7 @@ func (w *tableWatcher) Next() (*Event, error) {
if w.opts.Destination == res.Route.Destination { if w.opts.Destination == res.Route.Destination {
return res, nil return res, nil
} }
continue
} }
case <-w.done: case <-w.done:
return nil, ErrWatcherStopped return nil, ErrWatcherStopped