我正在尝试处理有关 Channels 的使用和正确处理的问题(很可能是设计问题)。我正在使用 Knative Eventing/Cloud Events 来创建和事件管道。
我希望能够处理不同的频道,以便接收来自不同来源/方法的事件。
为了做到这一点,我有下面的实现(为了简洁地详细说明问题,代码已被删除)。
我有一个file1.go
定义EventHandler
结构、关联方法和几个导出方法(CreatePreview()
和SaveAndPublish()
),它们是应用程序的“正常”行为,实际上接收/处理通道上的任何值:
type EventHandler struct {
Channel chan string
}
func (ev *EventHandler) Handle(event cloudevents.Event) {
if event.Data == nil {
(...)
}
var data string
if err := event.DataAs(&data); err != nil {
(...)
}
ev.Channel <- data
defer close(ev.Channel)
}
func (ev *EventHandler) Create(param *Element) (error) {
(...) //Unimportant code
}
func (repo *Repository) CreatePreview(param1 string, param2 string, eventHandler *EventHandler) (*pb.PreviewResponse, error) {
(...)
err := eventHandler.Create(&document)
(...)
preview := <- eventHandler.Channel
(...)
}
func (repo *Repository) SaveAndPublish(param1 string, param2 bool, eventHandler *EventHandler) (*pb.PublishResponse, error) {
(...)
err := eventHandler.Create(&documentToUpdate)
(...)
published := <- eventHandler.Channel
(...)
return repo.SomeOtherMethod(published.ID)
}
现在,在我的main.go
函数中,我有一个服务的“常规”启动,包括一个 gRPC 侦听器、一个 HTTP 侦听器和事件处理。这是通过cmux
. 所以这是代码示例(再次,代码简化):
func HandlerWrapper(event cloudevents.Event) {
//TODO: HOW DO I HANDLE THIS???
}
// This approach seems to cause issues since it's always the same instance
// var (
// eventHandler = &rep.EventHandler{Channel: make(chan string)}
// )
func (service *RPCService) Start() (err error) {
port, err := strconv.Atoi(os.Getenv("LISTEN_PORT"))
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
lis, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
// Create multiplexer and listener types
mux := cmux.New(lis)
grpcLis := mux.Match(cmux.HTTP2())
httpLis := mux.Match(cmux.HTTP1())
// *************
// gRPC
// *************
service.server = grpc.NewServer()
reflection.Register(service.server)
pb.RegisterStoryServiceServer(service.server, service)
// *************
// HTTP
// *************
// Declare new CloudEvents Receiver
c, err := kncloudevents.NewDefaultClient(httpLis)
if err != nil {
log.Fatal("Failed to create client, ", err)
}
// *************
// Start Listeners
// *************
// start gRPC server
go func() {
if err := service.server.Serve(grpcLis); err != nil {
log.Fatalf("failed to gRPC serve: %s", err)
}
}()
// start HTTP server
go func() {
// With this line bellow, I'd have to create a Received per eventHandler. Not cool
// log.Fatal(c.StartReceiver(context.Background(), eventHandler.Handle))
// Here we use a wrapper to deal with the event handling and have a single listener
log.Fatal(c.StartReceiver(context.Background(), HandlerWrapper))
}()
if err := mux.Serve(); err != nil {
log.Fatalf("failed to Mux serve: %s", err)
}
return
}
//CreatePreview is used to save a preview for a story
func (service *RPCService) CreatePreview(ctx context.Context, input *pb.PreviewRequest) (*pb.PreviewResponse, error){
eventHandler := &rep.EventHandler{Channel: make(chan string)}
story, err := service.repo.CreatePreview("param1", "param2", eventHandler)
if err != nil {
return nil, err
}
// Return matching the `CreatePreviewResponse` message we created in our
// protobuf definition.
return &pb.PreviewResponse{Story: story}, nil
}
// SaveAndPublish is used to save a story and publish it, returning the story saved.
func (service *RPCService) SaveAndPublish(ctx context.Context, input *pb.PublishRequest) (*pb.PublishResponse, error){
eventHandler := &rep.EventHandler{Channel: make(chan string)}
story, err := service.repo.SaveAndPublish("param1", true, eventHandler)
if err != nil {
return nil, err
}
// Return matching the `SaveAndPublishResponse` message we created in our
// protobuf definition.
return &pb.PublishResponse{Story: story}, nil
}
现在,我知道不必实例化单个 global eventHandler
,为了使用eventHandler.Handle
on c.StartReceiver()
on方法,main.go
我可以定义一个包装器,它可能包含一个 eventHandlers 列表(HandlerWrapper()
方法 on main.go
)。
但是,我不知道如何识别 an 的哪个实例EventHandler
是哪个以及如何正确处理和路由这些操作,这是我的问题:
我该如何处理这种情况,我想创建一个 Wrapper(一个要传入的函数c.StartReceive()
),然后让它由 的正确实例处理Handle()
?
我希望这个问题很清楚。几天来,我一直在努力解决这个问题,但不知道该怎么做。