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| package main | |
| import ( | |
| "context" | |
| "errors" | |
| "fmt" | |
| "io/ioutil" | |
| "log" | |
| "net/http" | |
| "reflect" | |
| "strings" | |
| "time" | |
| "github.com/gorilla/websocket" | |
| "github.com/rs/xlog" | |
| ) | |
| // Component represents a runnable component | |
| type Component interface { | |
| Run(ctx context.Context) | |
| } | |
| // Graph is a graph network | |
| // has a map ot registered elements | |
| type Graph struct { | |
| ctx context.Context | |
| cancel context.CancelFunc | |
| components map[string]Component | |
| channels []reflect.Value | |
| bufferCapacity int | |
| } | |
| // AddNode is used to give a name to the Component, so it can be used in the AddEdge function | |
| // ex: AddNodeComponent("read", c) | |
| func (n *Graph) AddNode(name string, c Component) error { | |
| if n.components == nil { | |
| n.components = make(map[string]Component) | |
| } | |
| n.components[name] = c | |
| return nil | |
| } | |
| func (n *Graph) AddInitial(in interface{}, definition string) error { | |
| left := strings.Split(definition, ".") | |
| c := strings.TrimSpace(left[0]) | |
| out := strings.TrimSpace(left[1]) | |
| inType := reflect.TypeOf(in) | |
| outType, _ := reflect.TypeOf(n.components[c]).Elem().FieldByName(out) | |
| if inType.Kind() != reflect.Chan { | |
| return errors.New("in must be a channel") | |
| } | |
| if outType.Type.Kind() != reflect.Chan { | |
| return errors.New("out must be a channel") | |
| } | |
| if inType != outType.Type { | |
| return errors.New("in and out must be the same channel types") | |
| } | |
| reflect.ValueOf(n.components[c]).Elem().FieldByName(out).Set(reflect.ValueOf(in)) | |
| return nil | |
| } | |
| // AddEdge connect the input and output of the given components | |
| // in -> out | |
| // Panic if element is not registered??? | |
| func (n *Graph) AddEdge(definition string) error { | |
| pieces := strings.Split(definition, "->") | |
| left := strings.Split(pieces[0], ".") | |
| a := strings.TrimSpace(left[0]) | |
| in := strings.TrimSpace(left[1]) | |
| right := strings.Split(pieces[1], ".") | |
| b := strings.TrimSpace(right[0]) | |
| out := strings.TrimSpace(right[1]) | |
| inType, _ := reflect.TypeOf(n.components[a]).Elem().FieldByName(in) | |
| outType, _ := reflect.TypeOf(n.components[b]).Elem().FieldByName(out) | |
| if inType.Type.Kind() != reflect.Chan { | |
| return errors.New("in must be a channel") | |
| } | |
| if outType.Type.Kind() != reflect.Chan { | |
| return errors.New("out must be a channel") | |
| } | |
| if inType.Type != outType.Type { | |
| return errors.New("in and out must be the same channel types") | |
| } | |
| edge := reflect.MakeChan(inType.Type, n.bufferCapacity) | |
| n.channels = append(n.channels, edge) | |
| reflect.ValueOf(n.components[a]).Elem().FieldByName(in).Set(edge) | |
| reflect.ValueOf(n.components[b]).Elem().FieldByName(out).Set(edge) | |
| return nil | |
| } | |
| // Run start all components | |
| func (n *Graph) Run(ctx context.Context) { | |
| n.ctx, n.cancel = context.WithCancel(ctx) | |
| for _, c := range n.components { | |
| go c.Run(n.ctx) | |
| } | |
| } | |
| // Shutdown sends a cancel to all the components of the graph | |
| // also should closes all the created channels. | |
| func (n *Graph) Shutdown() { | |
| n.cancel() | |
| for _, c := range n.channels { | |
| c.Close() | |
| } | |
| } | |
| type readComponent struct { | |
| in chan StringWithContext `port:"in"` | |
| out chan string `port:"out"` | |
| err chan string `port:"error"` | |
| } | |
| func (r *readComponent) Run(ctx context.Context) { | |
| for { | |
| select { | |
| case message := <-r.in: | |
| log := xlog.FromContext(message.ctx) | |
| log.Info("Reading", xlog.F{ | |
| "message": message.str, | |
| }) | |
| content, err := ioutil.ReadFile(message.str) | |
| if err != nil { | |
| log.Error("Error", xlog.F{ | |
| "error": err, | |
| }) | |
| r.err <- err.Error() | |
| continue | |
| } | |
| r.out <- string(content) | |
| case <-ctx.Done(): | |
| return | |
| } | |
| } | |
| } | |
| type sendRequestComponent struct { | |
| URL chan StringWithContext `port:"url"` | |
| Message chan StringWithContext `port:"message"` | |
| Err chan string `port:"err"` | |
| } | |
| func (s *sendRequestComponent) Run(ctx context.Context) { | |
| for { | |
| select { | |
| case url := <-s.URL: | |
| response, err := http.Get(url.str) | |
| if err != nil { | |
| s.Err <- err.Error() | |
| continue | |
| } | |
| data, err := ioutil.ReadAll(response.Body) | |
| if err != nil { | |
| s.Err <- err.Error() | |
| continue | |
| } | |
| s.Message <- NewStringWithContext(url.ctx, string(data)) | |
| response.Body.Close() | |
| case <-ctx.Done(): | |
| return | |
| } | |
| } | |
| } | |
| type Notifier struct { | |
| In chan StringWithContext | |
| } | |
| func (n *Notifier) Run(ctx context.Context) { | |
| for { | |
| select { | |
| case content := <-n.In: | |
| ws := content.ctx.Value("ws").(*websocket.Conn) | |
| ws.WriteJSON(content.str) | |
| case <-ctx.Done(): | |
| return | |
| } | |
| } | |
| } | |
| type Writer struct { | |
| In chan string | |
| } | |
| func (w *Writer) Run(ctx context.Context) { | |
| for { | |
| select { | |
| case content := <-w.In: | |
| fmt.Println(content) | |
| case <-ctx.Done(): | |
| return | |
| } | |
| } | |
| } | |
| type LowerCaseString struct { | |
| In chan StringWithContext | |
| Out chan StringWithContext | |
| } | |
| func (l *LowerCaseString) Run(ctx context.Context) { | |
| for { | |
| select { | |
| case data := <-l.In: | |
| l.Out <- NewStringWithContext(data.ctx, strings.ToLower(data.str)) | |
| case <-ctx.Done(): | |
| return | |
| } | |
| } | |
| } | |
| type StringWithContext struct { | |
| ctx context.Context | |
| str string | |
| } | |
| func NewStringWithContext(ctx context.Context, str string) StringWithContext { | |
| return StringWithContext{ | |
| ctx: ctx, | |
| str: str, | |
| } | |
| } | |
| func main() { | |
| initial := make(chan StringWithContext) | |
| graph := &Graph{ | |
| bufferCapacity: 10, | |
| } | |
| graph.AddNode("LowerCaseString", new(LowerCaseString)) | |
| graph.AddNode("Notifier", new(Notifier)) | |
| // graph.AddNode("SendRequest", new(sendRequestComponent)) | |
| //graph.AddEdge("LowerCaseString.Out -> SendRequest.URL", make(chan string)) | |
| graph.AddEdge("LowerCaseString.Out -> Notifier.In") | |
| // graph.AddEdge("SendRequest.Message -> Notifier.In") | |
| graph.AddInitial(initial, "LowerCaseString.In") | |
| graph.Run(context.Background()) | |
| defer graph.Shutdown() | |
| var upgrader = websocket.Upgrader{ | |
| CheckOrigin: func(r *http.Request) bool { | |
| return true | |
| }, | |
| } | |
| http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { | |
| ws, err := upgrader.Upgrade(w, r, nil) | |
| if err != nil { | |
| log.Println("upgrade:", err) | |
| return | |
| } | |
| defer ws.Close() | |
| ctx, cancel := context.WithTimeout(r.Context(), 5*time.Minute) | |
| defer cancel() | |
| go func() { | |
| for { | |
| var message string | |
| err := ws.ReadJSON(&message) | |
| if err != nil { | |
| log.Printf("readjson: %s", err) | |
| return | |
| } | |
| another := context.WithValue(ctx, "ws", ws) | |
| initial <- NewStringWithContext(another, message) | |
| } | |
| }() | |
| <-ctx.Done() | |
| }) | |
| http.ListenAndServe(":8080", nil) | |
| } |
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