125 lines
2.5 KiB
Go
125 lines
2.5 KiB
Go
package router
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import (
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"errors"
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"sync"
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"time"
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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("watcher stopped")
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)
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// EventType defines routing table event
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type EventType int
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const (
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// Create is emitted when a new route has been created
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Create EventType = iota
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// Delete is emitted when an existing route has been deleted
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Delete
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// Update is emitted when an existing route has been updated
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Update
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)
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// String returns human readable event type
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func (t EventType) String() string {
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switch t {
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case Create:
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return "create"
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case Delete:
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return "delete"
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case Update:
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return "update"
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default:
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return "unknown"
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}
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}
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// Event is returned by a call to Next on the watcher.
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type Event struct {
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// Unique id of the event
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Id string
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// Type defines type of event
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Type EventType
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// Timestamp is event timestamp
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Timestamp time.Time
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// Route is table route
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Route Route
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}
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// Watcher defines routing table watcher interface
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// Watcher 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() (*Event, error)
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// Chan returns event channel
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Chan() (<-chan *Event, error)
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// Stop stops watcher
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Stop()
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}
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// WatchOption is used to define what routes to watch in the table
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type WatchOption func(*WatchOptions)
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// WatchOptions are table watcher options
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// TODO: expand the options to watch based on other criteria
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type WatchOptions struct {
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// Service allows to watch specific service routes
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Service string
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}
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// WatchService sets what service routes to watch
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// Service is the microservice name
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func WatchService(s string) WatchOption {
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return func(o *WatchOptions) {
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o.Service = s
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}
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}
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// tableWatcher implements routing table Watcher
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type tableWatcher struct {
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sync.RWMutex
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id string
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opts WatchOptions
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resChan chan *Event
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done chan struct{}
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}
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// Next returns the next noticed action taken on table
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// TODO: right now we only allow to watch particular service
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func (w *tableWatcher) Next() (*Event, 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.Service {
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case res.Route.Service, "*":
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return res, nil
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default:
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continue
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}
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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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// Chan returns watcher events channel
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func (w *tableWatcher) Chan() (<-chan *Event, error) {
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return w.resChan, nil
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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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w.Lock()
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defer w.Unlock()
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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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