106 lines
2.7 KiB
Go
106 lines
2.7 KiB
Go
package httpapi
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import (
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"encoding/json"
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"errors"
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"fmt"
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"net/http"
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"strconv"
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"strings"
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"time"
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"data-terminal-cloud/internal/identity"
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"data-terminal-cloud/internal/webevents"
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)
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func StreamWebEventsHandler(service *webevents.Service) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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principal, ok := identity.PrincipalFromContext(r.Context())
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if !ok {
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WriteError(w, r, http.StatusUnauthorized, "AUTHENTICATION_REQUIRED", "请先登录后再访问")
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return
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}
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lastIDText := strings.TrimSpace(r.Header.Get("Last-Event-ID"))
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var cursor int64
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var err error
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if lastIDText == "" {
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cursor, err = service.StartingCursor(r.Context(), principal)
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} else {
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cursor, err = strconv.ParseInt(lastIDText, 10, 64)
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if err == nil && cursor < 1 {
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err = errors.New("cursor must be positive")
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}
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if err == nil {
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err = service.ValidateCursor(r.Context(), principal, cursor)
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}
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}
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if err != nil {
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status := http.StatusBadRequest
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code := "EVENT_CURSOR_INVALID"
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message := "状态事件编号无效"
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if errors.Is(err, webevents.ErrCursorUnavailable) {
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status = http.StatusGone
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code = "EVENT_CURSOR_EXPIRED"
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message = "状态事件续传窗口已过期，请重新载入页面"
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}
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WriteError(w, r, status, code, message)
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return
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}
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w.Header().Set("Content-Type", "text/event-stream; charset=utf-8")
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w.Header().Set("Cache-Control", "no-store")
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w.Header().Set("Connection", "keep-alive")
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w.Header().Set("X-Accel-Buffering", "no")
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controller := http.NewResponseController(w)
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_ = controller.SetWriteDeadline(time.Time{})
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if _, err := fmt.Fprintf(w, "retry: 2000\nid: %d\n\n", cursor); err != nil {
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return
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}
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if err := controller.Flush(); err != nil {
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return
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}
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poll := time.NewTicker(500 * time.Millisecond)
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heartbeat := time.NewTicker(10 * time.Second)
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end := time.NewTimer(25 * time.Second)
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defer poll.Stop()
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defer heartbeat.Stop()
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defer end.Stop()
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for {
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select {
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case <-r.Context().Done():
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return
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case <-end.C:
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return
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case <-heartbeat.C:
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if _, err := fmt.Fprint(w, ": heartbeat\n\n"); err != nil {
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return
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}
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if err := controller.Flush(); err != nil {
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return
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}
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case <-poll.C:
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items, err := service.ListAfter(r.Context(), principal, cursor, 100)
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if err != nil {
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return
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}
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for _, item := range items {
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payload, err := json.Marshal(item)
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if err != nil {
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return
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}
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if _, err := fmt.Fprintf(w, "id: %d\nevent: %s\ndata: %s\n\n", item.ID, item.Type, payload); err != nil {
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return
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}
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cursor = item.ID
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}
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if len(items) > 0 {
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if err := controller.Flush(); err != nil {
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return
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}
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}
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}
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}
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})
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}
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