feat: use sse to fetch new messages (close #70)

controller/message-sse.go

@@ -0,0 +1,56 @@
+package controller
+
+import (
+	"github.com/gin-gonic/gin"
+	"io"
+	"message-pusher/model"
+	"sync"
+)
+
+var messageChanBufferSize = 10
+
+var messageChanStore struct {
+	Map   map[int]*chan *model.Message
+	Mutex sync.RWMutex
+}
+
+func messageChanStoreAdd(messageChan *chan *model.Message, userId int) {
+	messageChanStore.Mutex.Lock()
+	defer messageChanStore.Mutex.Unlock()
+	messageChanStore.Map[userId] = messageChan
+}
+
+func messageChanStoreRemove(userId int) {
+	messageChanStore.Mutex.Lock()
+	defer messageChanStore.Mutex.Unlock()
+	delete(messageChanStore.Map, userId)
+}
+
+func init() {
+	messageChanStore.Map = make(map[int]*chan *model.Message)
+}
+
+func syncMessageToUser(message *model.Message, userId int) {
+	messageChanStore.Mutex.RLock()
+	defer messageChanStore.Mutex.RUnlock()
+	messageChan, ok := messageChanStore.Map[userId]
+	if !ok {
+		return
+	}
+	*messageChan <- message
+}
+
+func GetNewMessages(c *gin.Context) {
+	userId := c.GetInt("id")
+	messageChan := make(chan *model.Message, messageChanBufferSize)
+	messageChanStoreAdd(&messageChan, userId)
+	c.Stream(func(w io.Writer) bool {
+		if msg, ok := <-messageChan; ok {
+			c.SSEvent("message", *msg)
+			return true
+		}
+		return false
+	})
+	messageChanStoreRemove(userId)
+	close(messageChan)
+}

controller/message.go

@@ -185,11 +185,13 @@ func saveAndSendMessage(user *model.User, message *model.Message, channel_ *mode
 		if err != nil {
 			return err
 		}
+		go syncMessageToUser(message, user.Id)
 	} else {
 		if message.Async {
 			return errors.New("异步发送消息需要用户具备消息持久化的权限")
 		}
 		message.Link = "unsaved" // This is for user to identify whether the message is saved
+		go syncMessageToUser(message, user.Id)
 	}
 	if !message.Async {
 		err := channel.SendMessage(message, user, channel_)