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go-micro/plugins/registry/proxy/watcher.go
2021-01-20 21:01:10 +00:00

114 lines
2.1 KiB
Go

package proxy
import (
"errors"
"net/http"
"time"
"github.com/gorilla/websocket"
log "github.com/asim/go-micro/v3/logger"
"github.com/asim/go-micro/v3/registry"
)
const (
pingTime = (readDeadline * 9) / 10
readLimit = 16384
readDeadline = 60 * time.Second
writeDeadline = 10 * time.Second
)
type watcher struct {
exit chan bool
conn *websocket.Conn
res chan *registry.Result
}
func (w *watcher) ping() {
ticker := time.NewTicker(pingTime)
defer ticker.Stop()
for {
select {
case <-ticker.C:
w.conn.SetWriteDeadline(time.Now().Add(writeDeadline))
err := w.conn.WriteMessage(websocket.PingMessage, []byte{})
if err != nil {
log.Errorf("watcher error writing ping message: %v", err)
return
}
case <-w.exit:
return
}
}
}
func (w *watcher) run() {
// set read limit/deadline
w.conn.SetReadLimit(readLimit)
w.conn.SetReadDeadline(time.Now().Add(readDeadline))
// set close handler
ch := w.conn.CloseHandler()
w.conn.SetCloseHandler(func(code int, text string) error {
err := ch(code, text)
w.Stop()
return err
})
// set pong handler
w.conn.SetPongHandler(func(string) error {
w.conn.SetReadDeadline(time.Now().Add(readDeadline))
return nil
})
// read results and send to res channel
for {
var res *registry.Result
if err := w.conn.ReadJSON(&res); err != nil {
log.Errorf("error unmarshaling result: %v", err)
return
}
select {
case w.res <- res:
case <-w.exit:
return
}
}
}
func (w *watcher) Next() (*registry.Result, error) {
select {
case <-w.exit:
return nil, errors.New("result chan stopped")
case r, ok := <-w.res:
if !ok {
return nil, errors.New("result chan stopped")
}
return r, nil
}
}
func (w *watcher) Stop() {
select {
case <-w.exit:
return
default:
close(w.exit)
}
}
func newWatcher(url string) (registry.Watcher, error) {
conn, _, err := websocket.DefaultDialer.Dial(url, make(http.Header))
if err != nil {
return nil, err
}
w := &watcher{
conn: conn,
exit: make(chan bool),
res: make(chan *registry.Result),
}
go w.ping()
go w.run()
return w, nil
}