// Subscribe watches etcd changes and generates structured events telling vulcand to add or delete frontends, hosts etc.
// It is a blocking function.
func (n *ng) Subscribe(changes chan interface{}, cancelC chan bool) error {
// This index helps us to get changes in sequence, as they were performed by clients.
waitIndex := uint64(0)
for {
response, err := n.client.Watch(n.etcdKey, waitIndex, true, nil, cancelC)
if err != nil {
switch err {
case etcd.ErrWatchStoppedByUser:
log.Infof("Stop watching: graceful shutdown")
return nil
default:
log.Errorf("unexpected error: %s, stop watching", err)
return err
}
}
waitIndex = response.EtcdIndex + 1
log.Infof("%s", responseToString(response))
change, err := n.parseChange(response)
if err != nil {
log.Warningf("Ignore '%s', error: %s", responseToString(response), err)
continue
}
if change != nil {
log.Infof("%v", change)
select {
case changes <- change:
case <-cancelC:
return nil
}
}
}
}
// Subscribe watches etcd changes and generates structured events telling vulcand to add or delete frontends, hosts etc.
// It is a blocking function.
func (n *ng) Subscribe(changes chan interface{}, cancelC chan bool) error {
w := n.kapi.Watcher(n.etcdKey, &etcd.WatcherOptions{AfterIndex: 0, Recursive: true})
for {
response, err := w.Next(n.context)
if err != nil {
switch err {
case context.Canceled:
log.Infof("Stop watching: graceful shutdown")
return nil
default:
log.Errorf("unexpected error: %s, stop watching", err)
return err
}
}
log.Infof("%s", responseToString(response))
change, err := n.parseChange(response)
if err != nil {
log.Warningf("Ignore '%s', error: %s", responseToString(response), err)
continue
}
if change != nil {
log.Infof("%v", change)
select {
case changes <- change:
case <-cancelC:
return nil
}
}
}
}