fix: fully support stream mode now (close #3)

common/custom_event.go

@@ -0,0 +1,82 @@
+// Copyright 2014 Manu Martinez-Almeida.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package common
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+type stringWriter interface {
+	io.Writer
+	writeString(string) (int, error)
+}
+
+type stringWrapper struct {
+	io.Writer
+}
+
+func (w stringWrapper) writeString(str string) (int, error) {
+	return w.Writer.Write([]byte(str))
+}
+
+func checkWriter(writer io.Writer) stringWriter {
+	if w, ok := writer.(stringWriter); ok {
+		return w
+	} else {
+		return stringWrapper{writer}
+	}
+}
+
+// Server-Sent Events
+// W3C Working Draft 29 October 2009
+// http://www.w3.org/TR/2009/WD-eventsource-20091029/
+
+var contentType = []string{"text/event-stream"}
+var noCache = []string{"no-cache"}
+
+var fieldReplacer = strings.NewReplacer(
+	"\n", "\\n",
+	"\r", "\\r")
+
+var dataReplacer = strings.NewReplacer(
+	"\n", "\ndata:",
+	"\r", "\\r")
+
+type CustomEvent struct {
+	Event string
+	Id    string
+	Retry uint
+	Data  interface{}
+}
+
+func encode(writer io.Writer, event CustomEvent) error {
+	w := checkWriter(writer)
+	return writeData(w, event.Data)
+}
+
+func writeData(w stringWriter, data interface{}) error {
+	dataReplacer.WriteString(w, fmt.Sprint(data))
+	if strings.HasPrefix(data.(string), "data") {
+		w.writeString("\n\n")
+	}
+	return nil
+}
+
+func (r CustomEvent) Render(w http.ResponseWriter) error {
+	r.WriteContentType(w)
+	return encode(w, r)
+}
+
+func (r CustomEvent) WriteContentType(w http.ResponseWriter) {
+	header := w.Header()
+	header["Content-Type"] = contentType
+
+	if _, exist := header["Cache-Control"]; !exist {
+		header["Cache-Control"] = noCache
+	}
+}

controller/relay.go

@@ -47,58 +47,60 @@ func Relay(c *gin.Context) {
 		return
 	}
 	defer resp.Body.Close()
-	scanner := bufio.NewScanner(resp.Body)
-	scanner.Split(func(data []byte, atEOF bool) (advance int, token []byte, err error) {
-		if atEOF && len(data) == 0 {
-			return 0, nil, nil
-		}
+	isStream := resp.Header.Get("Content-Type") == "text/event-stream"
+	if isStream {
+		scanner := bufio.NewScanner(resp.Body)
+		scanner.Split(func(data []byte, atEOF bool) (advance int, token []byte, err error) {
+			if atEOF && len(data) == 0 {
+				return 0, nil, nil
+			}
 
-		if i := strings.Index(string(data), "\n\n"); i >= 0 {
-			return i + 2, data[0:i], nil
-		}
+			if i := strings.Index(string(data), "\n\n"); i >= 0 {
+				return i + 2, data[0:i], nil
+			}
 
-		if atEOF {
-			return len(data), data, nil
-		}
+			if atEOF {
+				return len(data), data, nil
+			}
 
-		return 0, nil, nil
-	})
-	dataChan := make(chan string)
-	stopChan := make(chan bool)
-	go func() {
-		for scanner.Scan() {
-			data := scanner.Text()
-			dataChan <- data
-		}
-		stopChan <- true
-	}()
-	for k, v := range resp.Header {
-		c.Writer.Header().Set(k, v[0])
-	}
-	c.Writer.Header().Set("Content-Type", "text/event-stream")
-	c.Writer.Header().Set("Cache-Control", "no-cache")
-	c.Writer.Header().Set("Connection", "keep-alive")
-	c.Writer.WriteHeaderNow()
-	//w := c.Writer
-	//flusher, _ := w.(http.Flusher)
-	c.Stream(func(w io.Writer) bool {
-		select {
-		case data := <-dataChan:
-			suffix := ""
-			if strings.HasPrefix(data, "data: ") {
-				suffix = "\n\n"
+			return 0, nil, nil
+		})
+		dataChan := make(chan string)
+		stopChan := make(chan bool)
+		go func() {
+			for scanner.Scan() {
+				data := scanner.Text()
+				dataChan <- data
 			}
-			_, err := fmt.Fprintf(w, "%s%s", data, suffix)
-			if err != nil {
+			stopChan <- true
+		}()
+		c.Writer.Header().Set("Content-Type", "text/event-stream")
+		c.Writer.Header().Set("Cache-Control", "no-cache")
+		c.Writer.Header().Set("Connection", "keep-alive")
+		c.Writer.Header().Set("Transfer-Encoding", "chunked")
+		c.Stream(func(w io.Writer) bool {
+			select {
+			case data := <-dataChan:
+				c.Render(-1, common.CustomEvent{Data: data})
+				return true
+			case <-stopChan:
 				return false
 			}
-			flusher, _ := w.(http.Flusher)
-			flusher.Flush()
-			//fmt.Println(data)
-			return true
-		case <-stopChan:
-			return false
+		})
+		return
+	} else {
+		for k, v := range resp.Header {
+			c.Writer.Header().Set(k, v[0])
+		}
+		_, err = io.Copy(c.Writer, resp.Body)
+		if err != nil {
+			c.JSON(http.StatusOK, gin.H{
+				"error": gin.H{
+					"message": err.Error(),
+					"type":    "one_api_error",
+				},
+			})
+			return
 		}
-	})
-	return
+	}
 }

main.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"embed"
-	"github.com/gin-contrib/gzip"
 	"github.com/gin-contrib/sessions"
 	"github.com/gin-contrib/sessions/cookie"
 	"github.com/gin-contrib/sessions/redis"
@@ -51,7 +50,8 @@ func main() {
 
 	// Initialize HTTP server
 	server := gin.Default()
-	server.Use(gzip.Gzip(gzip.DefaultCompression))
+	// This will cause SSE not to work!!!
+	//server.Use(gzip.Gzip(gzip.DefaultCompression))
 	server.Use(middleware.CORS())
 
 	// Initialize session store