1）持久化

Agenda 引入mongodb从而实现持久化 。Agenda 将所有的义务（job）存储到mongodb中，对于使用mongodb做数据库的项目有自然优势。

2）结构

在 Agenda 启动时会将预界说好的 processors 遍历一遍，从mongodb中查询出相符条件 job（这里的 job 可能不止一条）。对于遍历查询出来的job：若是时间已到或者已经是已往时间，那么立刻执行；若是时间还未到，那么就延迟执行。

3）API

Agenda 之所以受欢迎，与其简朴天真的 API 是分不开的。

Agenda安装

npm install agenda

使用

const mongoConnectionString = 'mongodb://127.0.0.1/agenda';

const agenda = new Agenda({db: {address: mongoConnectionString}});

// Or override the default collection name:
// const agenda = new Agenda({db: {address: mongoConnectionString, collection: 'jobCollectionName'}});

// or pass additional connection options:
// const agenda = new Agenda({db: {address: mongoConnectionString, collection: 'jobCollectionName', options: {ssl: true}}});

// or pass in an existing mongodb-native MongoClient instance
// const agenda = new Agenda({mongo: myMongoClient});

agenda.define('delete old users', (job, done) => {
  User.remove({lastLogIn: {$lt: twoDaysAgo}}, done);
});

(async function() { // IIFE to give access to async/await
  await agenda.start();

  await agenda.every('3 minutes', 'delete old users');

  // Alternatively, you could also do:
  await agenda.every('*/3 * * * *', 'delete old users');
})();