add codes contents for message pub/sub

gomore/27_messages/message.go

@@ -1,6 +1,7 @@
 package gomore
 
 import (
+	"context"
 	"errors"
 	"time"
 )
@@ -19,9 +20,9 @@ type User struct {
 	Name string
 }
 
-//Session of user
+//Session inherit user
 type Session struct {
-	User      User
+	User
 	Timestamp time.Time
 }
 
@@ -29,33 +30,80 @@ type Session struct {
 //Subscription is a session
 type Subscription struct {
 	Session
-	ch    chan<- Message //发送队列
-	Inbox <-chan Message //接收消息的队列
+	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
 }
 
+func newSubscription(uid uint64, topicName string, UserQueueSize int) Subscription {
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	return Subscription{
+		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
+	}
+
+}
+
+//Cancel Message
+func (s *Subscription) Cancel() {
+	s.cancel()
+}
+
+//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 {
-	if _, ok := <-s.ch; !ok {
-		return errors.New("Topic has been closed")
-	}
-	//用go channel 作为队列,接收消息
-	s.ch <- msg
 
+	select {
+	case <-s.ctx.Done():
+		return errors.New("Topic has been closed")
+	default:
+		s.ch <- msg
+	}
+	return nil
+}
+
+//Receive message
+func (s *Subscription) Receive(out *Message) error {
+
+	select {
+	case <-s.ctx.Done():
+		return errors.New("Topic has been closed")
+	default:
+		*out <- s.Inbox
+	}
 	return nil
 }
 
 //Topic that user is interested in
 //Topic locate in MQ
 type Topic struct {
+	UserQueueSize  int
 	Name           string
-	Subscribers    map[uint64]Session //user list
-	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
-	subscription   Subscription
+	Subscribers    map[uint64]Subscription //user list
+	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
+	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]
 }
 
 //String remove Subscription
@@ -63,47 +111,42 @@ func (t *Topic) String() string {
 	return t.Name
 }
 
-func (t *Topic) findSession(uid uint64) (Session, bool) {
+func (t *Topic) findUserSubscription(uid uint64, topicName string) (Subscription, bool) {
 	// Get session or create one if it's the first
-	var Session session
-	if t.Subscribers == nil || len(t.Subscribers) == 0 {
-		return Session{}, false
-	}
-	if session, found := t.Subscribers[uid]; found {
-		return session, true
-	}
-	return Session{}, false
-}
 
-func (t *Topic) addSession(uid uint64) Session {
-
-	var Session session
-	// Get session or create one if it's the first
-	if session, found := t.findSession(uid); !found {
-		if t.Subscribers == ni {
-			t.Subscribers = make(map[uint64]Session)
-		}
-		session = Session{User{uid, "no name"}, time.Now()}
-		t.Subscribers[uid] = session
+	if topicName != t.Name || t.Subscribers == nil || len(t.Subscribers) == 0 {
+		return Subscription{}, false
 	}
-	return session
+	if subscription, found := t.Subscribers[uid]; found {
+		return subscription, true
+	}
+	return Subscription{}, false
 }
 
 //Subscribe a spec topic
-func (t *Topic) Subscribe(uid uint64) (Subscription, error) {
+func (t *Topic) Subscribe(uid uint64, topicName string) (Subscription, bool) {
 
-	session := t.addSession(uid)
+	if t.Name != topicName {
+		return Subscription{}, false
+	}
 
-	// Create a subscription from copy
-	subscription := Subscription{session, t.subscription.ch, t.subscription.Inbox}
+	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
+	}
 
-	return subscription, nil
+	return subscription, true
 }
 
 //Unsubscribe remove Subscription
 func (t *Topic) Unsubscribe(s Subscription) error {
-	if t.findSession(s.User.ID) {
-		delete(t.Subscribers, s.User.ID)
+	if _, found := t.findUserSubscription(s.ID, s.topicName); found {
+		delete(t.Subscribers, s.ID)
 	}
 	return nil
 }
@@ -113,6 +156,5 @@ func (t *Topic) Delete() error {
 	t.Subscribers = nil
 	t.Name = ""
 	t.MessageHistory = nil
-	t.subscription = Subscription{}
 	return nil
 }

gomore/27_messages/message_test.go

@@ -1,15 +1,88 @@
 package gomore
 
-import "testing"
+import (
+	"fmt"
+	"testing"
+	"time"
+)
 
+////////////////////////////////
+//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 := MesssageQueue{Topics: map[uint64]*Topic{}}
+	msgQueue := Queue{Topics: map[string]Topic{}}
 
-	//创建一个话题
-	topic := Topic{}
+	//创建一个感兴趣的话题
+	topic := msgQueue.AddTopic("i want apple", 10)
+
+	//向队列订阅话题
+	if subSCription123, ok := topic.Subscribe(123, "tom want apple"); ok {
+
+		//订阅成功了
+
+		go func() {
+			EXIT
+			for {
+				select {
+				case <-exit:
+					break EXIT
+				default:
+					msg := Message{}
+					subSCription123.Receive(&msg)
+					fmt.Println(msg)
+				}
+				time.Sleep(200)
+			}
+		}()
+
+		msg := Message{
+			//Type 类型[code :1,2,3,4]
+			Type: 1,
+			Text: "here is a apple",
+			From: Session{User{123, "lily"}, time.Now()},
+		}
+		subSCription123.Publish(msg)
+		msg.Type++
+		subSCription123.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{
+			//Type 类型[code :1,2,3,4]
+			Type: 1,
+			Text: "here is a peach",
+			From: Session{User{123, "bob"}, time.Now()},
+		}
+
+		subSCription456.Publish(msg)
+
+		msg.Type++
+
+		subSCription456.Publish(msg)
+
+	}
 
-	//像队列订阅话题
-	topic.Subscribe(123)
 }