walle-module/lib/index.js

walle by node-red module

const config=require('./config');

//定义一个缓存，用来对比数据值判断
function cacheHandle() {
    //默认预设metric计数缓存对象
    const cache = new Map();
    const metric={total:0,filter:0};
    cache.set('metric',metric);
    return cache;
}

/**
 * 过滤方法
 * @param {*} payload 判断被过滤数据体,对象
 * @returns T:新数据被新缓存 F：数值没变化抛弃
 */
function messageFilter(payload,cache) {
    let receiveDeviceId=payload.deviceId;
    let monitor=payload.monitor;
    let receiveKey=receiveDeviceId+monitor;
    let receiveValue = payload.statusValue;
    if (cache.has(receiveKey)) {
        let oldValue = cache.get(receiveKey);
         //过滤逻辑
         if (receiveValue==oldValue) {
            return false;
         }else{
            cache.set(receiveKey, receiveValue);
            return true;
         }
    }
    cache.set(receiveKey, receiveValue);
    return true;
}


module.exports={
    config: config,
    filter: messageFilter,
    cache: cacheHandle
};