NodeJS CLS

• Continuation Local Storage - 连续本地存储
• AsyncLocalStorage - node v12.17+
  • 类似 ThreadLocal
  • getStore, setStore
  • disable
  • enterWith - 当前环境 - AsyncResource 上下文
  • run - callback 内生效
  • exit - callback 内失效
  • AsyncLocalStorage.snapshot
• AsyncResource

// ALS
// v13.10.0, v12.17.0
import { AsyncLocalStorage, AsyncResource } from 'node:async_hooks';
const asyncLocalStorage = new AsyncLocalStorage();
asyncLocalStorage.run(123, () => {
  console.log(`Store: ${asyncLocalStorage.getStore()}`);
  setImmediate(() => {
    console.log(`setImmediate Store: ${asyncLocalStorage.getStore()}`);
  });
});

• async_hooks - node v8+
  • currentId()
  • triggerAsyncId()
  • executionAsyncId()
• https://nodejs.org/api/async_context.html

// node 8+
import { createHook } from 'async_hooks';
const hook = createHook({
  init: (asyncId, type, triggerId, resource) => {},
  before: (asyncId) => {},
  after: (asyncId) => {},
  destroy: (asyncId) => {},
});
hook.enable();

• @fastify/request-context
  • asynchronous-local-storage
  • async_hooks
    • new AsyncResource('fastify-request-context')
  • onRequest - 包装运行环境
    • als.runWith
      • AsyncResource.runInAsyncScope(done,req,raw)

const { als } = require('asynchronous-local-storage');
const requestContext = {
  get: als.get,
  set: als.set,
};

• https://sequelize.org/docs/v7/other-topics/transactions
  • const namespace = cls.createNamespace('sequelize-tx');
  • useCLS
    • get, set, bind, run
    • bind(fn,context): ()=>any
  • prepareEnvironment
    • 开启事务
    • this.sequelize.Sequelize._cls.set('transaction', this);
• asynchronous-local-storage
  • Node.js ALS with fallback to cls-hooked
• cls-hooked
  • node 4.7+ - async-hook-jl
  • node 8+ - async_hooks
  • fork 自 continuation-local-storage
• continuation-local-storage

const cls = require('cls-hooked');
const namespace = cls.createNamespace('my-very-own-namespace');