// Watch runs Watch RPCs in parallel on the backends and returns a
// merged stream of results.
func (s *server) Watch(req *pb.Request, stream pb.Google_WatchServer) error { // HL
ctx := stream.Context()
c := make(chan result) // HL
var wg sync.WaitGroup
for _, b := range s.backends {
wg.Add(1)
go func(backend pb.GoogleClient) { // HL
defer wg.Done() // HL
watchBackend(ctx, backend, req, c) // HL
}(b) // HL
}
go func() {
wg.Wait()
close(c) // HL
}()
for res := range c { // HL
if res.err != nil {
return res.err
}
if err := stream.Send(res.res); err != nil { // HL
return err // HL
} // HL
}
return nil
}
// Watch returns a stream of results identifying the query and this
// backend, sleeping a random interval between each send.
func (s *server) Watch(req *pb.Request, stream pb.Google_WatchServer) error { // HL
ctx := stream.Context()
for i := 0; ; i++ {
d := randomDuration(1 * time.Second)
logSleep(ctx, d) // HL
select {
case <-time.After(d):
err := stream.Send(&pb.Result{ // HL
Title: fmt.Sprintf("result %d for [%s] from backend %d", i, req.Query, *index), // HL
}) // HL
if err != nil {
return err
}
case <-ctx.Done():
return ctx.Err()
}
}
}