micro/router/table.go

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package router
import (
"errors"
"sync"
"time"
"github.com/google/uuid"
)
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()
for _, w := range t.watchers {
select {
case w.resChan <- e:
case <-w.done:
}
}
}
// 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)
t.routes[service][sum] = r
go t.sendEvent(&Event{Type: Create, Timestamp: time.Now(), Route: r})
return nil
}
// add new route to the table for the route destination
if _, ok := t.routes[service][sum]; !ok {
t.routes[service][sum] = r
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
}
delete(t.routes[service], sum)
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)
t.routes[service][sum] = r
go t.sendEvent(&Event{Type: Create, Timestamp: time.Now(), Route: r})
return nil
}
t.routes[service][sum] = r
go t.sendEvent(&Event{Type: Update, Timestamp: time.Now(), Route: 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, gateway, network, router string) bool {
if gateway == "*" || gateway == route.Gateway {
if network == "*" || network == route.Network {
if router == "*" || router == route.Router {
return true
}
}
}
return false
}
// findRoutes finds all the routes for given network and router and returns them
func findRoutes(routes map[uint64]Route, gateway, network, router string) []Route {
var results []Route
for _, route := range routes {
if isMatch(route, gateway, network, router) {
results = append(results, route)
}
}
return results
}
// Lookup queries routing table and returns all routes that match the lookup query
func (t *table) Query(q Query) ([]Route, error) {
t.RLock()
defer t.RUnlock()
if q.Options().Service != "*" {
if _, ok := t.routes[q.Options().Service]; !ok {
return nil, ErrRouteNotFound
}
return findRoutes(t.routes[q.Options().Service], q.Options().Gateway, q.Options().Network, q.Options().Router), nil
}
var results []Route
// search through all destinations
for _, routes := range t.routes {
results = append(results, findRoutes(routes, q.Options().Gateway, q.Options().Network, q.Options().Router)...)
}
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
}