90 lines
1.9 KiB
Go
90 lines
1.9 KiB
Go
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package router
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import (
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"errors"
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)
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var (
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// ErrWatcherStopped is returned when routing table watcher has been stopped
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ErrWatcherStopped = errors.New("routing table watcher stopped")
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)
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// Watcher is an interface that returns updates to the routing table
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type Watcher interface {
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// Next is a blocking call that returns watch result
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Next() (*Result, error)
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// Stop stops watcher
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Stop()
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}
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// Result is returned by a call to Next on the watcher.
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type Result struct {
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// Action is routing table action which is either of add, remove or update
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Action string
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// Route is table rout
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Route Route
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}
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// Watcher options
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type WatchOptions struct {
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// Specify destination address to watch
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DestAddr string
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// Specify network to watch
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Network string
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}
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// WatchDestAddr sets what destination to watch
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// Destination is usually microservice name
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func WatchDestAddr(a string) WatchOption {
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return func(o *WatchOptions) {
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o.DestAddr = a
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}
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}
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// WatchNetwork sets what network to watch
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func WatchNetwork(n string) WatchOption {
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return func(o *WatchOptions) {
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o.Network = n
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}
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}
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type tableWatcher struct {
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opts WatchOptions
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resChan chan *Result
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done chan struct{}
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}
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// TODO: We might simply use Query here once QueryLookup is figured out
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// Next returns the next noticed action taken on table
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func (w *tableWatcher) Next() (*Result, error) {
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for {
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select {
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case res := <-w.resChan:
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switch w.opts.DestAddr {
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case "*":
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if w.opts.Network == "*" || w.opts.Network == res.Route.Options().Network {
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return res, nil
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}
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case res.Route.Options().DestAddr:
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if w.opts.Network == "*" || w.opts.Network == res.Route.Options().Network {
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return res, nil
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}
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}
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// ignore if no match is found
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continue
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case <-w.done:
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return nil, ErrWatcherStopped
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}
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}
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}
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// Stop stops routing table watcher
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func (w *tableWatcher) Stop() {
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select {
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case <-w.done:
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return
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default:
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close(w.done)
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}
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}
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