micro/router/table.go

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package router
import (
"errors"
"sync"
"time"
"github.com/google/uuid"
"github.com/micro/go-micro/v2/util/log"
)
var (
// ErrRouteNotFound is returned when no route was found in the routing table
ErrRouteNotFound = errors.New("route not found")
// ErrDuplicateRoute is returned when the route already exists
ErrDuplicateRoute = errors.New("duplicate route")
)
// table is an in-memory routing table
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type table struct {
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sync.RWMutex
// routes stores service routes
routes map[string]map[uint64]Route
// watchers stores table watchers
watchers map[string]*tableWatcher
}
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// newtable creates a new routing table and returns it
func newTable(opts ...Option) *table {
return &table{
routes: make(map[string]map[uint64]Route),
watchers: make(map[string]*tableWatcher),
}
}
// sendEvent sends events to all subscribed watchers
func (t *table) sendEvent(e *Event) {
t.RLock()
defer t.RUnlock()
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if len(e.Id) == 0 {
e.Id = uuid.New().String()
}
for _, w := range t.watchers {
select {
case w.resChan <- e:
case <-w.done:
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// don't block forever
case <-time.After(time.Second):
}
}
}
// Create creates new route in the routing table
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func (t *table) Create(r Route) error {
service := r.Service
sum := r.Hash()
t.Lock()
defer t.Unlock()
// check if there are any routes in the table for the route destination
if _, ok := t.routes[service]; !ok {
t.routes[service] = make(map[uint64]Route)
}
// add new route to the table for the route destination
if _, ok := t.routes[service][sum]; !ok {
t.routes[service][sum] = r
log.Debugf("Router emitting %s for route: %s", Create, r.Address)
go t.sendEvent(&Event{Type: Create, Timestamp: time.Now(), Route: r})
return nil
}
return ErrDuplicateRoute
}
// Delete deletes the route from the routing table
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func (t *table) Delete(r Route) error {
service := r.Service
sum := r.Hash()
t.Lock()
defer t.Unlock()
if _, ok := t.routes[service]; !ok {
return ErrRouteNotFound
}
if _, ok := t.routes[service][sum]; !ok {
return ErrRouteNotFound
}
delete(t.routes[service], sum)
log.Debugf("Router emitting %s for route: %s", Delete, r.Address)
go t.sendEvent(&Event{Type: Delete, Timestamp: time.Now(), Route: r})
return nil
}
// Update updates routing table with the new route
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func (t *table) Update(r Route) error {
service := r.Service
sum := r.Hash()
t.Lock()
defer t.Unlock()
// check if the route destination has any routes in the table
if _, ok := t.routes[service]; !ok {
t.routes[service] = make(map[uint64]Route)
}
if _, ok := t.routes[service][sum]; !ok {
t.routes[service][sum] = r
log.Debugf("Router emitting %s for route: %s", Update, r.Address)
go t.sendEvent(&Event{Type: Update, Timestamp: time.Now(), Route: r})
return nil
}
// just update the route, but dont emit Update event
t.routes[service][sum] = r
return nil
}
// List returns a list of all routes in the table
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func (t *table) List() ([]Route, error) {
t.RLock()
defer t.RUnlock()
var routes []Route
for _, rmap := range t.routes {
for _, route := range rmap {
routes = append(routes, route)
}
}
return routes, nil
}
// isMatch checks if the route matches given query options
func isMatch(route Route, address, gateway, network, router string, strategy Strategy) bool {
// matches the values provided
match := func(a, b string) bool {
if a == "*" || a == b {
return true
}
return false
}
// a simple struct to hold our values
type compare struct {
a string
b string
}
// by default assume we are querying all routes
link := "*"
// if AdvertiseLocal change the link query accordingly
if strategy == AdvertiseLocal {
link = "local"
}
// compare the following values
values := []compare{
{gateway, route.Gateway},
{network, route.Network},
{router, route.Router},
{address, route.Address},
{link, route.Link},
}
for _, v := range values {
// attempt to match each value
if !match(v.a, v.b) {
return false
}
}
return true
}
// findRoutes finds all the routes for given network and router and returns them
func findRoutes(routes map[uint64]Route, address, gateway, network, router string, strategy Strategy) []Route {
// routeMap stores the routes we're going to advertise
routeMap := make(map[string][]Route)
for _, route := range routes {
if isMatch(route, address, gateway, network, router, strategy) {
// add matchihg route to the routeMap
routeKey := route.Service + "@" + route.Network
// append the first found route to routeMap
_, ok := routeMap[routeKey]
if !ok {
routeMap[routeKey] = append(routeMap[routeKey], route)
continue
}
// if AdvertiseAll, keep appending
if strategy == AdvertiseAll || strategy == AdvertiseLocal {
routeMap[routeKey] = append(routeMap[routeKey], route)
continue
}
// now we're going to find the best routes
if strategy == AdvertiseBest {
// if the current optimal route metric is higher than routing table route, replace it
if len(routeMap[routeKey]) > 0 {
// NOTE: we know that when AdvertiseBest is set, we only ever have one item in current
if routeMap[routeKey][0].Metric > route.Metric {
routeMap[routeKey][0] = route
continue
}
}
}
}
}
var results []Route
for _, route := range routeMap {
results = append(results, route...)
}
return results
}
// Lookup queries routing table and returns all routes that match the lookup query
func (t *table) Query(q ...QueryOption) ([]Route, error) {
t.RLock()
defer t.RUnlock()
// create new query options
opts := NewQuery(q...)
// create a cwslicelist of query results
results := make([]Route, 0, len(t.routes))
// if No routes are queried, return early
if opts.Strategy == AdvertiseNone {
return results, nil
}
if opts.Service != "*" {
if _, ok := t.routes[opts.Service]; !ok {
return nil, ErrRouteNotFound
}
return findRoutes(t.routes[opts.Service], opts.Address, opts.Gateway, opts.Network, opts.Router, opts.Strategy), nil
}
// search through all destinations
for _, routes := range t.routes {
results = append(results, findRoutes(routes, opts.Address, opts.Gateway, opts.Network, opts.Router, opts.Strategy)...)
}
return results, nil
}
// Watch returns routing table entry watcher
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func (t *table) Watch(opts ...WatchOption) (Watcher, error) {
// by default watch everything
wopts := WatchOptions{
Service: "*",
}
for _, o := range opts {
o(&wopts)
}
w := &tableWatcher{
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id: uuid.New().String(),
opts: wopts,
resChan: make(chan *Event, 10),
done: make(chan struct{}),
}
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// when the watcher is stopped delete it
go func() {
<-w.done
t.Lock()
delete(t.watchers, w.id)
t.Unlock()
}()
// save the watcher
t.Lock()
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t.watchers[w.id] = w
t.Unlock()
return w, nil
}