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go-micro/plugins/registry/kubernetes/client/watch/body.go
2020-12-26 15:32:45 +00:00

93 lines
1.5 KiB
Go

package watch
import (
"bufio"
"encoding/json"
"net/http"
"time"
)
// bodyWatcher scans the body of a request for chunks
type bodyWatcher struct {
results chan Event
stop chan struct{}
res *http.Response
req *http.Request
}
// Changes returns the results channel
func (wr *bodyWatcher) ResultChan() <-chan Event {
return wr.results
}
// Stop cancels the request
func (wr *bodyWatcher) Stop() {
select {
case <-wr.stop:
return
default:
close(wr.stop)
close(wr.results)
}
}
func (wr *bodyWatcher) stream() {
reader := bufio.NewReader(wr.res.Body)
// ignore first few messages from stream,
// as they are usually old.
ignore := true
go func() {
<-time.After(time.Second)
ignore = false
}()
go func() {
for {
// read a line
b, err := reader.ReadBytes('\n')
if err != nil {
return
}
// ignore for the first second
if ignore {
continue
}
// send the event
var event Event
if err := json.Unmarshal(b, &event); err != nil {
continue
}
wr.results <- event
}
// stop the watcher
wr.Stop()
}()
}
// NewBodyWatcher creates a k8s body watcher for
// a given http request
func NewBodyWatcher(req *http.Request, client *http.Client) (Watch, error) {
stop := make(chan struct{})
req.Cancel = stop
res, err := client.Do(req)
if err != nil {
return nil, err
}
wr := &bodyWatcher{
results: make(chan Event),
stop: stop,
req: req,
res: res,
}
go wr.stream()
return wr, nil
}