// remote_api.js 模擬第三方 API'use strict';const app = require('express')();app.get('/', (req, res) => {  setTimeout(() => {    let arr = [200, 300]; // 200 代表成功，300 代表失敗需要重新請(qǐng)求    res.status(200).send({ 'status': arr[parseInt(Math.random() * 2)] });  }, 3000);});app.listen('9001', () => {  console.log('API 服務(wù)監(jiān)聽(tīng)端口：9001');});// producer.js 自身應(yīng)用 API，用來(lái)接受用戶請(qǐng)求并將任務(wù)加入任務(wù)隊(duì)列'use strict';const app = require('express')();const redisClient = require('redis').createClient();const QUEUE_NAME = 'queue:example';function addTaskToQueue(taskName, callback) {  // 先判斷任務(wù)是否已經(jīng)存在，存在：跳過(guò)，不存在：加入任務(wù)隊(duì)列  redisClient.zscore(QUEUE_NAME, taskName, (error, task) => {    if (error) {      console.log(error);    } else {      if (task) {        console.log('任務(wù)已存在，不新增相同任務(wù)');        callback(null, task);      } else {        redisClient.zadd(QUEUE_NAME, new Date().getTime(), taskName, (error, result) => {          if (error) {            callback(error);          } else {            callback(null, result);          }        });      }    }  });}app.get('/', (req, res) => {  let taskName = req.query['task-name'];  addTaskToQueue(taskName, (error, result) => {    if (error) {      console.log(error);    } else {      res.status(200).send('正在查詢中......');    }  });});app.listen(9002, () => {  console.log('生產(chǎn)者服務(wù)監(jiān)聽(tīng)端口：9002');});// consumer.js 定時(shí)獲取任務(wù)并執(zhí)行'use strict';const redisClient = require('redis').createClient();const request = require('request');const schedule = require('node-schedule');const QUEUE_NAME = 'queue:expmple';const PARALLEL_TASK_NUMBER = 2; // 并行執(zhí)行任務(wù)數(shù)量function getTasksFromQueue(callback) {  // 獲取多個(gè)任務(wù)  redisClient.zrangebyscore([QUEUE_NAME, 1, new Date().getTime(), 'LIMIT', 0, PARALLEL_TASK_NUMBER], (error, tasks) => {    if (error) {      callback(error);    } else {      // 將任務(wù)分值設(shè)置為 0，表示正在處理      if (tasks.length > 0) {        let tmp = [];        tasks.forEach((task) => {          tmp.push(0);          tmp.push(task);        });        redisClient.zadd([QUEUE_NAME].concat(tmp), (error, result) => {          if (error) {            callback(error);          } else {            callback(null, tasks)          }        });      }    }  });}function addFailedTaskToQueue(taskName, callback) {  redisClient.zadd(QUEUE_NAME, new Date().getTime(), taskName, (error, result) => {    if (error) {      callback(error);    } else {      callback(null, result);    }  });}function removeSucceedTaskFromQueue(taskName, callback) {  redisClient.zrem(QUEUE_NAME, taskName, (error, result) => {    if (error) {      callback(error);    } else {      callback(null, result);    }  })}function execTask(taskName) {  return new Promise((resolve, reject) => {    let requestOptions = {      'url': 'http://127.0.0.1:9001',      'method': 'GET',      'timeout': 5000    };    request(requestOptions, (error, response, body) => {      if (error) {        resolve('failed');        console.log(error);        addFailedTaskToQueue(taskName, (error) => {          if (error) {            console.log(error);          } else {          }        });      } else {        try {          body = typeof body !== 'object' ? JSON.parse(body) : body;        } catch (error) {          resolve('failed');          console.log(error);          addFailedTaskToQueue(taskName, (error, result) => {            if (error) {              console.log(error);            } else {            }          });          return;        }        if (body.status !== 200) {          resolve('failed');          addFailedTaskToQueue(taskName, (error, result) => {            if (error) {              console.log(error);            } else {            }          });        } else {          resolve('succeed');          removeSucceedTaskFromQueue(taskName, (error, result) => {            if (error) {              console.log(error);            } else {            }          });        }      }    });  });}// 定時(shí)，每隔 5 秒獲取新的任務(wù)來(lái)執(zhí)行l(wèi)et job = schedule.scheduleJob('*/5 * * * * *', () => {  console.log('獲取新任務(wù)');  getTasksFromQueue((error, tasks) => {    if (error) {      console.log(error);    } else {      if (tasks.length > 0) {        console.log(tasks);        Promise.all(tasks.map(execTask))        .then((results) => {          console.log(results);        })        .catch((error) => {          console.log(error);        });              }    }  });});