nodejs redis 发布订阅机制封装

   最近项目使用redis，对publish 和 subscribe的使用进行了了解，并进行了封装。

  

var config = require('../config/config');
var log = require("./loghelp");
var redis = require("redis");
function initialclient(param) {
    var option={ host: config.redis.host, port: config.redis.port};
    if(param)
    {
        option=Object.assign(option,param);
    }
    redis.print
    let client = redis.createClient(option);
    client.on("error", function(err) {
        log.error(err);
    });
    return client;
}

/*example:
* let channel="ryan";
 redis.pubSub.registerHandlers("ryan",msg=> console.log(msg));
 redis.pubSub.subscribe(channel);

 redis.pubSub.publish(channel,"hello from chen");*/
class PubSub
{
    constructor(){
        this.sub=initialclient();
        this.handlers=new Map();
        this.subAction=(channle,message)=>{
            let actions= this.handlers.get(channle)||new Set();
            for(let action of actions)
            {
                action(message);
            }
        }
        this.alredyPublishs=[];
        this.subConnected=false;
    }

    publish(channel,message)
    {
        let action=()=>{
            let pub=initialclient();
            pub.publish(channel,message);
        };
        if(this.subConnected===false)
        {
            this.alredyPublishs.push(action);
        }
        else
            action();
    }
    registerHandlers(channel,action)
    {
       var actions=this.handlers.get(channel)||new Set();
       actions.add(action);
       this.handlers.set(channel,actions);
    }
    subscribe(channel)
    {
        let self=this;
        this.sub.subscribe(channel,function (err,reply) {
            if(err)
                log.error(err);
            self.subConnected=true;
            for(let publish of self.alredyPublishs)
                publish();
            console.log(reply);
        });

        this.sub.on("message", function (channel, message) {
            self.subAction(channel,message);
        });
    }

    tearDown()
    {
        this.sub.quit();
    }
}

然后通过exports.pubsub=new PubSub() 将其暴漏，可保证是单例。在程序启动时，调用

registerHandlers  注册特定通道的处理逻辑，然后调用

subscribe  订阅通道。

在合适时机调用publish，这个机制可以实现分布式下所有客户端watch 同一个数据的更改。