triggerAsyncId

triggerAsyncId 是导致（或 "triggered"）新资源初始化并导致 init 调用的资源的 asyncId。这不同于 async_hooks.executionAsyncId() 只显示资源创建时间，而 triggerAsyncId 显示资源创建原因。

¥triggerAsyncId is the asyncId of the resource that caused (or "triggered") the new resource to initialize and that caused init to call. This is different from async_hooks.executionAsyncId() that only shows when a resource was created, while triggerAsyncId shows why a resource was created.

下面是 triggerAsyncId 的简单演示：

¥The following is a simple demonstration of triggerAsyncId:

import { createHook, executionAsyncId } from 'node:async_hooks';
import { stdout } from 'node:process';
import net from 'node:net';
import fs from 'node:fs';

createHook({
  init(asyncId, type, triggerAsyncId) {
    const eid = executionAsyncId();
    fs.writeSync(
      stdout.fd,
      `${type}(${asyncId}): trigger: ${triggerAsyncId} execution: ${eid}\n`);
  },
}).enable();

net.createServer((conn) => {}).listen(8080);const { createHook, executionAsyncId } = require('node:async_hooks');
const { stdout } = require('node:process');
const net = require('node:net');
const fs = require('node:fs');

createHook({
  init(asyncId, type, triggerAsyncId) {
    const eid = executionAsyncId();
    fs.writeSync(
      stdout.fd,
      `${type}(${asyncId}): trigger: ${triggerAsyncId} execution: ${eid}\n`);
  },
}).enable();

net.createServer((conn) => {}).listen(8080);拷贝

当使用 nc localhost 8080 访问服务器时的输出：

¥Output when hitting the server with nc localhost 8080:

TCPSERVERWRAP(5): trigger: 1 execution: 1
TCPWRAP(7): trigger: 5 execution: 0 拷贝

TCPSERVERWRAP 是接收连接的服务器。

¥The TCPSERVERWRAP is the server which receives the connections.

TCPWRAP 是来自客户端的新连接。当建立新连接时，则立即构造 TCPWrap 实例。这发生在任何 JavaScript 堆栈之外。（executionAsyncId() 或 0 意味着它是从 C++ 执行的，上面没有 JavaScript 堆栈。）仅凭该信息，不可能根据资源创建的原因将资源链接在一起，因此 triggerAsyncId 的任务是传播哪些资源负责新资源的存在。

¥The TCPWRAP is the new connection from the client. When a new connection is made, the TCPWrap instance is immediately constructed. This happens outside of any JavaScript stack. (An executionAsyncId() of 0 means that it is being executed from C++ with no JavaScript stack above it.) With only that information, it would be impossible to link resources together in terms of what caused them to be created, so triggerAsyncId is given the task of propagating what resource is responsible for the new resource's existence.