我想实现的功能是生产者生产一批数据后， 触发full事件。 消费者开始消费数据， 消费之后，触发empty事件， 生产者开始生产数据…

下面的代码执行的结果是生产者生产了数据之后，消费者消费了数据， 但不能触发生产者再造数据了。 因为我侦错到Empty的生产者监听器数量为0. 这是为什么？ 1.index文件

var event_pattern = require('./event_pattern');
var readline = require('readline');
var util = require('util');

//实例化一个生产者和两个消费者
var producer = new event_pattern.Producer();

var consumer1 = new event_pattern.Consumer('A');
var consumer2 = new event_pattern.Consumer('B');
//消费者订阅生产者full事件
producer.on('full', consumer1.consume);
producer.on('full', consumer2.consume);
//生产者订阅消费者empty事件
consumer1.on('empty', producer.produce);
consumer2.on('empty', producer.produce);

producer.produce();

2.生产者与消费者模块

var events = require('events');
var console = require('console');
var util = require('util');

function Producer() {

    events.EventEmitter.call(this);

    var totalCount = totalCount || 100;

    var currentCount=0;

    this.produce = function(beans) {

        if (!util.isArray(beans)) {
            beans = [];
        }

        var i = 0;
        var bean;

        while (i < 18 && currentCount++ < totalCount) {

            bean = Math.round(Math.random() * 100);

            beans.push(bean);

            console.log("produce: " + bean);

            i++;

        }

        console.log("full listeners: " + this.listenerCount('full'));
        this.emit('full', beans, this);

    };

};

util.inherits(Producer, events.EventEmitter);

function Consumer(name) {

    events.EventEmitter.call(this);

    this.name = name;

    this.consume = function(beans) {

        var i = 0;

        while (i < 10 && beans.length > 0) {
            var bean = beans.shift();
            console.log(name + "consume: " + bean);
            i++;
        }

        if (beans.length == 0) {
             console.log("empty listeners: " + this.listenerCount('empty'));//值为0，为什么没有任何监听器了？？？？？
            var hasListeners = this.emit('empty', beans);
        }

    };

}

Consumer.prototype=new events.EventEmitter();
Consumer.prototype.constructor=Consumer;