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package client
import (
"context"
"encoding/json"
"github.com/donovanhide/eventsource"
)
type EventMayPromoteChange struct {
ResourceName string `json:"resource_name,omitempty"`
NodeName string `json:"node_name,omitempty"`
MayPromote bool `json:"may_promote,omitempty"`
}
// custom code
// EventProvider acts as an abstraction for an EventService. It can be swapped
// out for another EventService implementation, for example for testing.
type EventProvider interface {
// DRBDPromotion is used to subscribe to LINSTOR DRBD Promotion events
DRBDPromotion(ctx context.Context, lastEventId string) (*DRBDMayPromoteStream, error)
}
const mayPromoteChange = "may-promote-change"
// EventService is the service that deals with LINSTOR server side event streams.
type EventService struct {
client *Client
}
// DRBDMayPromoteStream is a struct that contains a channel of EventMayPromoteChange events
// It has a Close() method that needs to be called/defered.
type DRBDMayPromoteStream struct {
Events chan EventMayPromoteChange
stream *eventsource.Stream
}
// Close is used to close the underlying stream and all Go routines
func (dmp *DRBDMayPromoteStream) Close() {
dmp.stream.Close()
}
// suscribe handles stream creation, event splitting, and context cancelation
func (e *EventService) subscribe(ctx context.Context, url, event, lastEventId string) (*eventsource.Stream, chan interface{}, error) {
stream, err := e.client.doEvent(ctx, url, lastEventId)
if err != nil {
return nil, nil, err
}
ch := make(chan interface{})
go func() {
defer close(ch)
for {
select {
case ev, ok := <-stream.Events:
if !ok { // most likely someone called Close()
return
}
if ev.Event() == event {
switch event {
case mayPromoteChange:
var empc EventMayPromoteChange
if err := json.Unmarshal([]byte(ev.Data()), &empc); err == nil {
ch <- empc
}
}
}
case <-ctx.Done():
return
}
}
}()
return stream, ch, nil
}
// DRBDPromotion is used to subscribe to LINSTOR DRBD Promotion events
func (e *EventService) DRBDPromotion(ctx context.Context, lastEventId string) (*DRBDMayPromoteStream, error) {
stream, ch, err := e.subscribe(ctx, "/v1/events/drbd/promotion", mayPromoteChange, lastEventId)
if err != nil {
return nil, err
}
empch := make(chan EventMayPromoteChange)
go func() {
defer close(empch)
for ev := range ch {
if e, ok := ev.(EventMayPromoteChange); ok {
empch <- e
}
}
}()
return &DRBDMayPromoteStream{
Events: empch,
stream: stream,
}, nil
}
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