mirror of
https://github.com/crazybber/go-pattern-examples.git
synced 2024-11-22 03:46:03 +03:00
159 lines
3.7 KiB
Go
159 lines
3.7 KiB
Go
package messaging
|
||
|
||
import (
|
||
"context"
|
||
"errors"
|
||
"fmt"
|
||
"time"
|
||
)
|
||
|
||
//Message for msg in Message bus
|
||
type Message struct {
|
||
Seq int
|
||
Text string
|
||
From Session //消息来源
|
||
}
|
||
|
||
//User for user
|
||
type User struct {
|
||
ID uint64
|
||
Name string
|
||
}
|
||
|
||
//Session inherit user
|
||
type Session struct {
|
||
User
|
||
Timestamp time.Time
|
||
}
|
||
|
||
//Subscription for user
|
||
//Subscription is a session
|
||
type Subscription struct {
|
||
Session
|
||
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 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 {
|
||
|
||
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")
|
||
case <-time.After(time.Millisecond * 100):
|
||
return errors.New("time out error")
|
||
case *out = <-s.Inbox:
|
||
return nil
|
||
}
|
||
}
|
||
|
||
//Topic that user is interested in
|
||
//Topic should locate in MQ
|
||
type Topic struct {
|
||
UserQueueSize int
|
||
Name string
|
||
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
|
||
}
|
||
|
||
//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 {
|
||
|
||
//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
|
||
}
|
||
}
|
||
//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) {
|
||
// Get session or create one if it's the first
|
||
|
||
if topicName != t.Name || t.Subscribers == nil || len(t.Subscribers) == 0 {
|
||
return Subscription{}, false
|
||
}
|
||
if subscription, found := t.Subscribers[uid]; found {
|
||
return subscription, true
|
||
}
|
||
return Subscription{}, false
|
||
}
|
||
|
||
//Subscribe a spec topic
|
||
func (t *Topic) Subscribe(uid uint64, topicName string) (Subscription, bool) {
|
||
|
||
if t.Name != topicName {
|
||
return Subscription{}, false
|
||
}
|
||
|
||
// 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)
|
||
}
|
||
t.Subscribers[uid] = newSubscription(uid, topicName, t.UserQueueSize)
|
||
}
|
||
|
||
return t.Subscribers[uid], true
|
||
}
|
||
|
||
//Unsubscribe remove Subscription
|
||
func (t *Topic) Unsubscribe(s Subscription) error {
|
||
if _, found := t.findUserSubscription(s.ID, s.topicName); found {
|
||
delete(t.Subscribers, s.ID)
|
||
}
|
||
return nil
|
||
}
|
||
|
||
//Delete topic
|
||
func (t *Topic) Delete() error {
|
||
t.Subscribers = nil
|
||
t.Name = ""
|
||
t.MessageHistory = nil
|
||
return nil
|
||
}
|