micro/network/router/default_table.go

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package router
import (
"fmt"
"hash"
"hash/fnv"
"strings"
"sync"
"github.com/google/uuid"
"github.com/olekukonko/tablewriter"
)
// TableOptions are routing table options
// TODO: table options TBD in the future
type TableOptions struct{}
// table is in memory routing table
type table struct {
// opts are table options
opts TableOptions
// m stores routing table map
m map[string]map[uint64]Route
// h hashes route entries
h hash.Hash64
// w is a list of table watchers
w map[string]*tableWatcher
sync.RWMutex
}
// newTable creates in memory routing table and returns it
func newTable(opts ...TableOption) Table {
// default options
var options TableOptions
// apply requested options
for _, o := range opts {
o(&options)
}
h := fnv.New64()
h.Reset()
return &table{
opts: options,
m: make(map[string]map[uint64]Route),
w: make(map[string]*tableWatcher),
h: h,
}
}
// Init initializes routing table with options
func (t *table) Init(opts ...TableOption) error {
for _, o := range opts {
o(&t.opts)
}
return nil
}
// Options returns routing table options
func (t *table) Options() TableOptions {
return t.opts
}
// Add adds a route to the routing table
func (t *table) Add(r Route) error {
destAddr := r.Destination
sum := t.hash(r)
t.Lock()
defer t.Unlock()
// check if the destination has any routes in the table
if _, ok := t.m[destAddr]; !ok {
t.m[destAddr] = make(map[uint64]Route)
t.m[destAddr][sum] = r
go t.sendEvent(&Event{Type: CreateEvent, Route: r})
return nil
}
// add new route to the table for the given destination
if _, ok := t.m[destAddr][sum]; !ok {
t.m[destAddr][sum] = r
go t.sendEvent(&Event{Type: CreateEvent, Route: r})
return nil
}
// only add the route if the route override is explicitly requested
if _, ok := t.m[destAddr][sum]; ok && r.Policy == OverrideIfExists {
t.m[destAddr][sum] = r
go t.sendEvent(&Event{Type: UpdateEvent, Route: r})
return nil
}
// if we reached this point without already returning the route already exists
// we return nil only if explicitly requested by the client
if r.Policy == IgnoreIfExists {
return nil
}
return ErrDuplicateRoute
}
// Delete deletes the route from the routing table
func (t *table) Delete(r Route) error {
t.Lock()
defer t.Unlock()
destAddr := r.Destination
sum := t.hash(r)
if _, ok := t.m[destAddr]; !ok {
return ErrRouteNotFound
}
delete(t.m[destAddr], sum)
go t.sendEvent(&Event{Type: DeleteEvent, Route: r})
return nil
}
// Update updates routing table with new route
func (t *table) Update(r Route) error {
destAddr := r.Destination
sum := t.hash(r)
t.Lock()
defer t.Unlock()
// check if the destAddr has ANY routes in the table
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
}
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if _, ok := t.m[destAddr][sum]; !ok && r.Policy == AddIfNotExists {
t.m[destAddr][sum] = r
go t.sendEvent(&Event{Type: CreateEvent, Route: r})
return nil
}
// if the route has been found update it
if _, ok := t.m[destAddr][sum]; ok {
t.m[destAddr][sum] = r
go t.sendEvent(&Event{Type: UpdateEvent, Route: r})
return nil
}
return ErrRouteNotFound
}
// List returns a list of all routes in the table
func (t *table) List() ([]Route, error) {
t.RLock()
defer t.RUnlock()
var routes []Route
for _, rmap := range t.m {
for _, route := range rmap {
routes = append(routes, route)
}
}
return routes, nil
}
// isMatch checks if the route matches given network and router
func isMatch(route Route, network, router string) bool {
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, network, router string) []Route {
var results []Route
for _, route := range routes {
if isMatch(route, network, router) {
results = append(results, route)
}
}
return results
}
// Lookup queries routing table and returns all routes that match the lookup query
func (t *table) Lookup(q Query) ([]Route, error) {
t.RLock()
defer t.RUnlock()
if q.Options().Destination != "*" {
// no routes found for the destination and query policy is not a DiscardIfNone
if _, ok := t.m[q.Options().Destination]; !ok && q.Options().Policy != DiscardIfNone {
return nil, ErrRouteNotFound
}
return findRoutes(t.m[q.Options().Destination], q.Options().Network, q.Options().Router), nil
}
var results []Route
// search through all destinations
for _, routes := range t.m {
results = append(results, findRoutes(routes, q.Options().Network, q.Options().Router)...)
}
return results, nil
}
// Watch returns routing table entry watcher
func (t *table) Watch(opts ...WatchOption) (Watcher, error) {
// by default watch everything
wopts := WatchOptions{
Destination: "*",
}
for _, o := range opts {
o(&wopts)
}
watcher := &tableWatcher{
opts: wopts,
resChan: make(chan *Event, 10),
done: make(chan struct{}),
}
t.Lock()
t.w[uuid.New().String()] = watcher
t.Unlock()
return watcher, nil
}
// sendEvent sends rules to all subscribe watchers
func (t *table) sendEvent(r *Event) {
t.RLock()
defer t.RUnlock()
for _, w := range t.w {
select {
case w.resChan <- r:
case <-w.done:
}
}
}
// Size returns the size of the routing table
func (t *table) Size() int {
t.RLock()
defer t.RUnlock()
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size := 0
for dest, _ := range t.m {
size += len(t.m[dest])
}
return size
}
// String returns debug information
func (t *table) String() string {
t.RLock()
defer t.RUnlock()
// this will help us build routing table string
sb := &strings.Builder{}
// create nice table printing structure
table := tablewriter.NewWriter(sb)
table.SetHeader([]string{"Destination", "Gateway", "Router", "Network", "Metric"})
for _, destRoute := range t.m {
for _, route := range destRoute {
strRoute := []string{
route.Destination,
route.Gateway,
route.Router,
route.Network,
fmt.Sprintf("%d", route.Metric),
}
table.Append(strRoute)
}
}
// render table into sb
table.Render()
return sb.String()
}
// hash hashes the route using router gateway and network address
func (t *table) hash(r Route) uint64 {
t.h.Reset()
t.h.Write([]byte(r.Destination + r.Gateway + r.Network))
return t.h.Sum64()
}