finish pub/sub pattern

gomore/27_messages/README.md

@@ -10,10 +10,12 @@
 
 图片来源：[pubsub-pattern.md](https://github.com/imsardine/dev-notes/blob/source/docs/pubsub-pattern.md)
 
-示例演示消息队的某个主题(Topic)收到用户订阅之后，的处理过程和与用户之间的响应互动。
+现实生活中的各种信息平台，就是很好的发布订阅的例子，比如某八戒、某无忧等
+
+这里演示，一个拼车例子，车主发布拼车(Topic)消息，消息推送到订阅拼车(Topic)信息的所有用户.
 
 并模拟以下情形：
 
-+ 主题向用户发送消息
-+ 用户订阅主题
-+ 用户发送某个主题消息
++ 车主(Topic)发布拼车消息
++ 拼车用户订阅拼车消息(Topic)
++ 拼车用户处理收到的拼车消息

gomore/27_messages/message.go

@@ -1,8 +1,9 @@
-package gomore
+package messaging
 
 import (
 	"context"
 	"errors"
+	"fmt"
 	"time"
 )
 
@@ -32,8 +33,8 @@ type Subscription struct {
 	topicName string
 	ctx       context.Context
 	cancel    context.CancelFunc
-	ch        chan<- Message //发送队列
-	Inbox     <-chan Message //接收消息的队列
+	Ch        chan<- Message //发送队列
+	Inbox     chan Message   //接收消息的队列
 }
 
 func newSubscription(uid uint64, topicName string, UserQueueSize int) Subscription {
@@ -44,8 +45,8 @@ func newSubscription(uid uint64, topicName string, UserQueueSize int) Subscripti
 		Session: Session{User{ID: uid}, time.Now()},
 		ctx:     ctx,
 		cancel:  cancel,
-		ch:      make(chan<- Message, UserQueueSize), //用于跟单个用户通信的消息队列，用户发送消息
-		Inbox:   make(<-chan Message, UserQueueSize), //用于跟单个用户通信的消息队列,用户接收消息
+		Ch:      make(chan<- Message, UserQueueSize), //用于跟单个用户通信的消息队列，用户发送消息
+		Inbox:   make(chan Message, UserQueueSize),   //用于跟单个用户通信的消息队列,用户接收消息
 	}
 
 }
@@ -55,6 +56,8 @@ func (s *Subscription) Cancel() {
 	s.cancel()
 }
 
+//Publish 这个表示用户订阅到感兴趣的主题的时候，同时也可以发送消息，
+//Publish 但是，示例中不演示这个用途
 //Publish 只有当channel无数据，且channel被close了，才会返回ok=false
 //Publish a message to subscription queue
 func (s *Subscription) Publish(msg Message) error {
@@ -63,7 +66,7 @@ func (s *Subscription) Publish(msg Message) error {
 	case <-s.ctx.Done():
 		return errors.New("Topic has been closed")
 	default:
-		s.ch <- msg
+		s.Ch <- msg
 	}
 	return nil
 }
@@ -74,14 +77,15 @@ func (s *Subscription) Receive(out *Message) error {
 	select {
 	case <-s.ctx.Done():
 		return errors.New("Topic has been closed")
-	default:
-		*out = <-s.Inbox
+	case <-time.After(time.Millisecond * 100):
+		return errors.New("time out error")
+	case *out = <-s.Inbox:
+		return nil
 	}
-	return nil
 }
 
 //Topic that user is interested in
-//Topic locate in MQ
+//Topic should locate in MQ
 type Topic struct {
 	UserQueueSize  int
 	Name           string
@@ -89,20 +93,22 @@ type Topic struct {
 	MessageHistory []Message               //当前主题的消息历史,实际项目中可能需要限定大小并设置过期时间
 }
 
-//Queue hold all topics
-type Queue struct {
-	Topics map[string]Topic //topic ID<-----> topic Object
-}
+//Publish 只有当channel无数据，且channel被close了，才会返回ok=false
+//Publish a message to subscription queue
+func (t *Topic) Publish(msg Message) error {
 
-//AddTopic to Queue
-func (q *Queue) AddTopic(topicName string, topicUserQueueSize int) Topic {
-	if q.Topics == nil {
-		q.Topics = make(map[string]Topic)
+	//将消息发布给当前Topic的所有人
+	for usersID, subscription := range t.Subscribers {
+		if subscription.ID == usersID {
+			subscription.Inbox <- msg
+		}
 	}
-	if _, found := q.Topics[topicName]; !found {
-		q.Topics[topicName] = Topic{UserQueueSize: topicUserQueueSize, Name: topicName}
-	}
-	return q.Topics[topicName]
+	//save message history
+	t.MessageHistory = append(t.MessageHistory, msg)
+
+	fmt.Println("current histroy message count: ", len(t.MessageHistory))
+
+	return nil
 }
 
 func (t *Topic) findUserSubscription(uid uint64, topicName string) (Subscription, bool) {
@@ -124,17 +130,15 @@ func (t *Topic) Subscribe(uid uint64, topicName string) (Subscription, bool) {
 		return Subscription{}, false
 	}
 
-	var subscription Subscription
 	// Get session or create one if it's the first
 	if _, found := t.findUserSubscription(uid, topicName); !found {
 		if t.Subscribers == nil {
 			t.Subscribers = make(map[uint64]Subscription)
 		}
-		subscription = newSubscription(uid, topicName, t.UserQueueSize)
-		t.Subscribers[uid] = subscription
+		t.Subscribers[uid] = newSubscription(uid, topicName, t.UserQueueSize)
 	}
 
-	return subscription, true
+	return t.Subscribers[uid], true
 }
 
 //Unsubscribe remove Subscription

gomore/27_messages/message_queue.go

@@ -0,0 +1,17 @@
+package messaging
+
+//Queue hold all topics
+type Queue struct {
+	Topics map[string]Topic //topic ID<-----> topic Object
+}
+
+//AddTopic to Queue
+func (q *Queue) AddTopic(topicName string, topicUserQueueSize int) Topic {
+	if q.Topics == nil {
+		q.Topics = make(map[string]Topic)
+	}
+	if _, found := q.Topics[topicName]; !found {
+		q.Topics[topicName] = Topic{UserQueueSize: topicUserQueueSize, Name: topicName}
+	}
+	return q.Topics[topicName]
+}

gomore/27_messages/message_test.go

@@ -1,7 +1,9 @@
-package gomore
+package messaging
 
 import (
+	"context"
 	"fmt"
+	"sync"
 	"testing"
 	"time"
 )
@@ -9,76 +11,99 @@ import (
 ////////////////////////////////
 //通常意义上是，连接消息队列之后就可以发送消息
 //当订阅著之后才会收到相关Topic消息的推送
-//这里为了简化，直接订阅成功后发送消息，省去连接消息队列发送消息的步骤
 ////////////////////////////////
-func TestMessageSubAndPub(t *testing.T) {
 
-	exit := make(chan bool, 1)
-	//创建一个队列
-	msgQueue := Queue{Topics: map[string]Topic{}}
+func TestMessageSubAndPubWithTopic(t *testing.T) {
+	var wg sync.WaitGroup
 
-	//创建一个感兴趣的话题
-	topic := msgQueue.AddTopic("i want apple", 10)
+	topicName := "seeking passengers"
+	//假设评估
+	topic := Topic{
+		Name:          topicName,
+		UserQueueSize: 5,
+	}
 
-	//向队列订阅话题
-	if subSCription123, ok := topic.Subscribe(123, "tom want apple"); ok {
+	ctx, cancel := context.WithCancel(context.Background())
 
-		//订阅成功了
+	wg.Add(1)
+	//user 1
+
+	//用户tom订阅拼车消息,订阅的是车主发布的拼车消息
+	if subScriberTom, ok := topic.Subscribe(123, topicName); ok {
 
 		go func() {
+			defer wg.Done()
 		EXIT:
 			for {
 				select {
-				case <-exit:
+				case <-ctx.Done():
+					fmt.Println("tom receive cancel, exit")
 					break EXIT
 				default:
 					msg := Message{}
-					subSCription123.Receive(&msg)
-					fmt.Println(msg)
+					err := subScriberTom.Receive(&msg)
+					if err == nil {
+						fmt.Println("tom receive subscribed msg:", msg)
+					}
 				}
 				time.Sleep(200)
 			}
 		}()
+	}
 
+	wg.Add(1)
+	//订阅成功了
+	//发送一个消息
+
+	//用户Lily订阅拼车消息,订阅的是车主发布的拼车消息
+	if subSCriptionLily, ok := topic.Subscribe(456, topicName); ok {
+		go func() {
+			defer wg.Done()
+		EXIT:
+			for {
+				select {
+				case <-ctx.Done():
+					fmt.Println("lily receive cancel, exit")
+					break EXIT
+				default:
+					msg := Message{}
+					err := subSCriptionLily.Receive(&msg)
+					if err == nil {
+						fmt.Println("lily receive subscribed msg:", msg)
+					}
+				}
+				time.Sleep(200)
+			}
+		}()
+	}
+
+	go func() {
+		//模拟发送消息
 		msg := Message{
-			Text: "here is a apple",
+			Text: "i am looking for 1 passenger",
 			From: Session{User{123, "lily"}, time.Now()},
 		}
-		subSCription123.Publish(msg)
-		msg.Seq++
-		subSCription123.Publish(msg)
-	}
+		topic.Publish(msg)
 
-	if subSCription456, ok := topic.Subscribe(456, "lily want peach"); ok {
-
-		//订阅成功了
-		//发送一个消息
-		go func() {
-		EXIT:
-			for {
-				select {
-				case <-exit:
-					break EXIT
-				default:
-					msg := Message{}
-					subSCription456.Receive(&msg)
-					fmt.Println(msg)
-				}
-				time.Sleep(200)
-			}
-		}()
-
-		msg := Message{
-			Text: "here is a peach",
-			From: Session{User{123, "bob"}, time.Now()},
+		msg = Message{
+			Text: "i am looking for 2 passenger",
+			From: Session{User{123, "lucy"}, time.Now()},
 		}
 
-		subSCription456.Publish(msg)
+		topic.Publish(msg)
 
-		msg.Seq++
+		msg = Message{
+			Text: "i am looking for passenger as many as i can",
+			From: Session{User{123, "rose"}, time.Now()},
+		}
 
-		subSCription456.Publish(msg)
+		topic.Publish(msg)
+		time.Sleep(time.Second)
+		cancel()
 
-	}
+	}()
+
+	wg.Wait()
+	fmt.Println("all message done,exit it")
 
 }