139 lines
2.6 KiB
Go
139 lines
2.6 KiB
Go
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package main
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import (
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"context"
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"encoding/json"
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"errors"
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"io"
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"log"
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"math/rand"
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"net/http"
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"sync"
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"time"
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)
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type Message struct {
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Time int64 `json:"time"`
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Message string `json:"message"`
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}
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type Channel struct {
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id string
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listeners map[int]listener
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last time.Time
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ctx context.Context
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mu sync.Mutex
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}
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type Server struct {
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channels map[string]*Channel
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mu sync.Mutex
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}
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type listener func(msg *Message)
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func main() {
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s := &Server{
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channels: make(map[string]*Channel),
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}
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go func() {
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for {
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time.Sleep(5 * time.Second)
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s.mu.Lock()
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log.Printf("channels: %d", len(s.channels))
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s.mu.Unlock()
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}
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}()
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http.HandleFunc("/", s.handle)
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if err := http.ListenAndServe(":9997", nil); err != nil {
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log.Fatalln(err)
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}
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}
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func (s *Server) handle(w http.ResponseWriter, r *http.Request) {
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if err := s.handleInternal(w, r); err != nil {
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w.WriteHeader(http.StatusInternalServerError)
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_, _ = io.WriteString(w, err.Error())
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}
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}
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func (s *Server) handleInternal(w http.ResponseWriter, r *http.Request) error {
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if len(r.URL.Path) == 0 {
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return errors.New("invalid path")
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}
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channel := s.channel(r.URL.Path[1:])
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switch r.Method {
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case http.MethodGet:
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return s.handleGET(w, r, channel)
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case http.MethodPut:
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return s.handlePUT(w, r, channel)
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default:
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return errors.New("invalid method")
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}
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}
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func (s *Server) handleGET(w http.ResponseWriter, r *http.Request, ch *Channel) error {
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fl, ok := w.(http.Flusher)
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if !ok {
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return errors.New("not a flusher")
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}
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listenerID := rand.Int()
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l := func (msg *Message) {
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json.NewEncoder(w).Encode(&msg)
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fl.Flush()
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}
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ch.mu.Lock()
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ch.listeners[listenerID] = l
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ch.last = time.Now()
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ch.mu.Unlock()
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select {
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case <-ch.ctx.Done():
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case <-r.Context().Done():
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}
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ch.mu.Lock()
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delete(ch.listeners, listenerID)
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if len(ch.listeners) == 0 {
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s.mu.Lock()
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delete(s.channels, ch.id)
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s.mu.Unlock()
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}
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ch.mu.Unlock()
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return nil
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}
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func (s *Server) handlePUT(w http.ResponseWriter, r *http.Request, ch *Channel) error {
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ch.mu.Lock()
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defer ch.mu.Unlock()
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if len(ch.listeners) == 0 {
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return errors.New("no listeners")
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}
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defer r.Body.Close()
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ch.last = time.Now()
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msg, _ := io.ReadAll(r.Body)
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for _, l := range ch.listeners {
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l(&Message{
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Time: time.Now().UnixMilli(),
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Message: string(msg),
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})
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}
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return nil
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}
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func (s *Server) channel(channelID string) *Channel {
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s.mu.Lock()
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defer s.mu.Unlock()
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c, ok := s.channels[channelID]
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if !ok {
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ctx, _ := context.WithCancel(context.Background()) // FIXME
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c = &Channel{
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id: channelID,
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listeners: make(map[int]listener),
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last: time.Now(),
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ctx: ctx,
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mu: sync.Mutex{},
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}
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s.channels[channelID] = c
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}
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return c
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}
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