// watcher for data change in etcd directory
func (p *service_pool) watcher() {
client := p.client_pool.Get().(*etcd.Client)
defer func() {
p.client_pool.Put(client)
}()
for {
ch := make(chan *etcd.Response, 10)
go func() {
for {
if resp, ok := <-ch; ok {
if resp.Node.Dir {
continue
}
key, value := resp.Node.Key, resp.Node.Value
if value == "" {
log.Tracef("node delete: %v", key)
p.remove_service(key)
} else {
log.Tracef("node add: %v %v", key, value)
p.add_service(key, value)
}
} else {
return
}
}
}()
_, err := client.Watch(DEFAULT_SERVICE_PATH, 0, true, ch, nil)
if err != nil {
log.Critical(err)
}
<-time.After(RETRY_DELAY)
}
}
// add a service
func (p *service_pool) add_service(key, value string) {
p.Lock()
defer p.Unlock()
service_name := filepath.Dir(key)
if p.services[service_name] == nil {
p.services[service_name] = &service{}
log.Tracef("new service type: %v", service_name)
}
service := p.services[service_name]
if conn, err := grpc.Dial(value, grpc.WithTimeout(DEFAULT_DIAL_TIMEOUT)); err == nil {
service.clients = append(service.clients, client{key, conn})
log.Tracef("service added: %v -- %v", key, value)
} else {
log.Errorf("did not connect: %v -- %v err: %v", key, value, err)
}
}
// remove a service
func (p *service_pool) remove_service(key string) {
p.Lock()
defer p.Unlock()
service_name := filepath.Dir(key)
service := p.services[service_name]
if service == nil {
log.Tracef("no such service %v", service_name)
return
}
for k := range service.clients {
if service.clients[k].key == key { // deletion
service.clients = append(service.clients[:k], service.clients[k+1:]...)
log.Tracef("service removed %v", key)
return
}
}
}
// subscribe to an endpoint & receive server streams
func (s *server) Subscribe(p *Chat_Id, stream ChatService_SubscribeServer) error {
// read endpoint
ep := s.read_ep(p.Id)
if ep == nil {
log.Errorf("cannot find endpoint %v", p)
return ERROR_NOT_EXISTS
}
// send history chat messages
msgs := ep.Read()
for k := range msgs {
if err := stream.Send(&msgs[k]); err != nil {
return nil
}
}
// create subscriber
e := make(chan error, 1)
var once sync.Once
f := NewSubscriber(func(msg *Chat_Message) {
if err := stream.Send(msg); err != nil {
once.Do(func() { // protect for channel blocking
e <- err
})
}
})
// subscribe to the endpoint
log.Tracef("subscribe to:%v", p.Id)
ep.ps.Sub(f)
defer func() {
ep.ps.Leave(f)
log.Tracef("leave from:%v", p.Id)
}()
// client send cancel to stop receiving, see service_test.go for example
select {
case <-stream.Context().Done():
case <-e:
log.Error(e)
}
return nil
}
// add a service
func (p *service_pool) add_service(key, value string) {
p.Lock()
defer p.Unlock()
service_name := filepath.Dir(key)
// name check
if p.enable_name_check && !p.service_names[service_name] {
log.Warningf("service not in names: %v, ignored", service_name)
return
}
if p.services[service_name] == nil {
p.services[service_name] = &service{}
log.Tracef("new service type: %v", service_name)
}
service := p.services[service_name]
if conn, err := grpc.Dial(value, grpc.WithTimeout(DEFAULT_DIAL_TIMEOUT), grpc.WithInsecure()); err == nil {
service.clients = append(service.clients, client{key, conn})
log.Tracef("service added: %v -- %v", key, value)
} else {
log.Errorf("did not connect: %v -- %v err: %v", key, value, err)
}
}