Make traces in development reliable

.eslintignore

@@ -26,3 +26,5 @@ packages/create-next-app/templates/**
 test/integration/eslint/**
 test-timings.json
 packages/next/build/swc/tests/fixture/**
+bench/nested-deps/pages/**
+bench/nested-deps/components/**

bench/nested-deps/.gitignore

@@ -0,0 +1 @@
+components/*

bench/nested-deps/fuzzponent.js

@@ -0,0 +1,182 @@
+#!/usr/bin/env node
+const path = require('path')
+const fs = require('fs')
+
+const getSequenceGenerator = require('random-seed')
+const generate = require('@babel/generator').default
+const t = require('@babel/types')
+
+const MIN_COMPONENT_NAME_LEN = 18
+const MAX_COMPONENT_NAME_LEN = 24
+const MIN_CHILDREN = 4
+const MAX_CHILDREN = 80
+
+const arrayUntil = (len) => [...Array(len)].map((_, i) => i)
+
+const generateFunctionalComponentModule = (componentName, children = []) => {
+  const body = [
+    generateImport('React', 'react'),
+    ...children.map((childName) => generateImport(childName, `./${childName}`)),
+    t.variableDeclaration('const', [
+      t.variableDeclarator(
+        t.identifier(componentName),
+        t.arrowFunctionExpression(
+          [],
+          t.parenthesizedExpression(
+            generateJSXElement(
+              'div',
+              children.map((childName) => generateJSXElement(childName))
+            )
+          )
+        )
+      ),
+    ]),
+    t.exportDefaultDeclaration(t.identifier(componentName)),
+  ]
+
+  return t.program(body, [], 'module')
+}
+
+const generateJSXElement = (componentName, children = null) =>
+  t.JSXElement(
+    t.JSXOpeningElement(t.JSXIdentifier(componentName), [], !children),
+    children ? t.JSXClosingElement(t.JSXIdentifier(componentName)) : null,
+    children || [],
+    !children
+  )
+
+const generateImport = (componentName, requireString) =>
+  t.importDeclaration(
+    [t.importDefaultSpecifier(t.identifier(componentName))],
+    t.stringLiteral(requireString)
+  )
+
+const validFirstChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+const validOtherChars = validFirstChars.toLowerCase()
+function generateComponentName(seqGenerator, opts) {
+  const numOtherChars = seqGenerator.intBetween(opts.minLen, opts.maxLen)
+  const firstChar = validFirstChars[seqGenerator.range(validFirstChars.length)]
+  const otherChars = arrayUntil(numOtherChars).map(
+    () => validOtherChars[seqGenerator.range(validOtherChars.length)]
+  )
+  return `${firstChar}${otherChars.join('')}`
+}
+
+function* generateModules(name, remainingDepth, seqGenerator, opts) {
+  const filename = `${name}.${opts.extension}`
+  let ast
+
+  if (name === 'index') {
+    name = 'RootComponent'
+  }
+
+  if (remainingDepth === 0) {
+    ast = generateFunctionalComponentModule(name)
+  } else {
+    const numChildren = seqGenerator.intBetween(opts.minChild, opts.maxChild)
+    const children = arrayUntil(numChildren).map(() =>
+      generateComponentName(seqGenerator, opts)
+    )
+    ast = generateFunctionalComponentModule(name, children)
+
+    for (const child of children) {
+      yield* generateModules(child, remainingDepth - 1, seqGenerator, opts)
+    }
+  }
+
+  yield {
+    filename,
+    content: generate(ast).code,
+  }
+}
+
+function generateFuzzponents(outdir, seed, depth, opts) {
+  const seqGenerator = getSequenceGenerator(seed)
+
+  const filenames = new Set()
+  for (const { filename, content } of generateModules(
+    'index',
+    depth,
+    seqGenerator,
+    opts
+  )) {
+    if (filenames.has(filename)) {
+      throw new Error(
+        `Seed "${seed}" generates output with filename collisions.`
+      )
+    } else {
+      filenames.add(filename)
+    }
+    const fpath = path.join(outdir, filename)
+    fs.writeFileSync(fpath, `// ${filename}\n\n${content}`)
+  }
+}
+
+if (require.main === module) {
+  const { outdir, seed, depth, ...opts } = require('yargs')
+    .option('depth', {
+      alias: 'd',
+      demandOption: true,
+      describe: 'component hierarchy depth',
+      type: 'number',
+    })
+    .option('seed', {
+      alias: 's',
+      demandOption: true,
+      describe: 'prng seed',
+      type: 'number',
+    })
+    .option('outdir', {
+      alias: 'o',
+      demandOption: false,
+      default: process.cwd(),
+      describe: 'the directory where components should be written',
+      type: 'string',
+      normalize: true,
+    })
+    .option('minLen', {
+      demandOption: false,
+      default: MIN_COMPONENT_NAME_LEN,
+      describe: 'the smallest acceptible component name length',
+      type: 'number',
+    })
+    .option('maxLen', {
+      demandOption: false,
+      default: MAX_COMPONENT_NAME_LEN,
+      describe: 'the largest acceptible component name length',
+      type: 'number',
+    })
+    .option('minLen', {
+      demandOption: false,
+      default: MIN_COMPONENT_NAME_LEN,
+      describe: 'the smallest acceptible component name length',
+      type: 'number',
+    })
+    .option('maxLen', {
+      demandOption: false,
+      default: MAX_COMPONENT_NAME_LEN,
+      describe: 'the largest acceptible component name length',
+      type: 'number',
+    })
+    .option('minChild', {
+      demandOption: false,
+      default: MIN_CHILDREN,
+      describe: 'the smallest number of acceptible component children',
+      type: 'number',
+    })
+    .option('maxChild', {
+      demandOption: false,
+      default: MAX_CHILDREN,
+      describe: 'the largest number of acceptible component children',
+      type: 'number',
+    })
+    .option('extension', {
+      default: 'jsx',
+      describe: 'extension to use for generated components',
+      type: 'string',
+    }).argv
+
+  generateFuzzponents(outdir, seed, depth, opts)
+}
+
+module.exports = generateFuzzponents

bench/nested-deps/next.config.js

@@ -0,0 +1,9 @@
+module.exports = {
+  eslint: {
+    ignoreDuringBuilds: true,
+  },
+  experimental: {
+    swcLoader: true,
+    swcMinify: true,
+  },
+}

bench/nested-deps/package.json

@@ -0,0 +1,10 @@
+{
+  "scripts": {
+    "prepare": "rm -rf components && node ./fuzzponent.js -d 2 -s 206 -o components",
+    "dev": "../../node_modules/.bin/next dev",
+    "build": "../../node_modules/.bin/next build",
+    "start": "../../node_modules/.bin/next start",
+    "dev-nocache": "rm -rf .next && yarn dev",
+    "build-nocache": "rm -rf .next && yarn build"
+  }
+}

bench/nested-deps/pages/index.jsx

@@ -0,0 +1,5 @@
+import Comp from '../components/index.jsx'
+
+export default function Home() {
+  return <Comp />
+}

package.json

@@ -47,6 +47,7 @@
     "@fullhuman/postcss-purgecss": "1.3.0",
     "@mdx-js/loader": "0.18.0",
     "@svgr/webpack": "5.5.0",
+    "@swc/cli": "0.1.49",
     "@swc/core": "1.2.85",
     "@swc/jest": "0.2.2",
     "@testing-library/react": "11.2.5",
@@ -117,6 +118,7 @@
     "prettier": "2.3.2",
     "pretty-bytes": "5.3.0",
     "pretty-ms": "7.0.0",
+    "random-seed": "0.3.0",
     "react": "17.0.2",
     "react-18": "npm:react@next",
     "react-dom": "17.0.2",

packages/next/build/babel/loader/index.ts

@@ -1,5 +1,5 @@
 import { getOptions } from 'next/dist/compiled/loader-utils'
-import { Span } from '../../../telemetry/trace'
+import { Span } from '../../../trace'
 import transform from './transform'
 import { NextJsLoaderContext } from './types'
 

packages/next/build/babel/loader/transform.ts

@@ -11,7 +11,7 @@ import PluginPass from 'next/dist/compiled/babel/core-lib-plugin-pass'
 
 import getConfig from './get-config'
 import { consumeIterator } from './util'
-import { Span } from '../../../telemetry/trace'
+import { Span } from '../../../trace'
 import { NextJsLoaderContext } from './types'
 
 function getTraversalParams(file: any, pluginPairs: any[]) {

packages/next/build/babel/loader/types.d.ts

@@ -1,5 +1,5 @@
 import { loader } from 'next/dist/compiled/webpack/webpack'
-import { Span } from '../../../telemetry/trace'
+import { Span } from '../../../trace'
 
 export interface NextJsLoaderContext extends loader.LoaderContext {
   currentTraceSpan: Span

packages/next/build/compiler.ts

@@ -1,5 +1,5 @@
 import { webpack } from 'next/dist/compiled/webpack/webpack'
-import { Span } from '../telemetry/trace'
+import { Span } from '../trace'
 
 export type CompilerResult = {
   errors: string[]
@@ -42,7 +42,9 @@ export function runCompiler(
   return new Promise((resolve, reject) => {
     const compiler = webpack(config)
     compiler.run((err: Error, stats: webpack.Stats) => {
-      const webpackCloseSpan = runWebpackSpan.traceChild('webpack-close')
+      const webpackCloseSpan = runWebpackSpan.traceChild('webpack-close', {
+        name: config.name,
+      })
       webpackCloseSpan
         .traceAsyncFn(() => closeCompiler(compiler))
         .then(() => {

packages/next/build/index.ts

@@ -73,7 +73,7 @@ import { generateBuildId } from './generate-build-id'
 import { isWriteable } from './is-writeable'
 import * as Log from './output/log'
 import createSpinner from './spinner'
-import { trace, flushAllTraces, setGlobal } from '../telemetry/trace'
+import { trace, flushAllTraces, setGlobal } from '../trace'
 import {
   collectPages,
   detectConflictingPaths,
@@ -1291,7 +1291,7 @@ export default async function build(
           },
         }
 
-        await exportApp(dir, exportOptions, exportConfig)
+        await exportApp(dir, exportOptions, nextBuildSpan, exportConfig)
 
         const postBuildSpinner = createSpinner({
           prefixText: `${Log.prefixes.info} Finalizing page optimization`,

packages/next/build/output/log.ts

@@ -7,6 +7,7 @@ export const prefixes = {
   ready: chalk.green('ready') + ' -',
   info: chalk.cyan('info') + '  -',
   event: chalk.magenta('event') + ' -',
+  trace: chalk.magenta('trace') + ' -',
 }
 
 export function wait(...message: string[]) {
@@ -32,3 +33,7 @@ export function info(...message: string[]) {
 export function event(...message: string[]) {
   console.log(prefixes.event, ...message)
 }
+
+export function trace(...message: string[]) {
+  console.log(prefixes.trace, ...message)
+}

packages/next/build/output/store.ts

@@ -1,5 +1,6 @@
 import createStore from 'next/dist/compiled/unistore'
 import stripAnsi from 'next/dist/compiled/strip-ansi'
+import { flushAllTraces } from '../../trace'
 
 import * as Log from './log'
 
@@ -88,4 +89,6 @@ store.subscribe((state) => {
   }
 
   Log.event('compiled successfully')
+  // Ensure traces are flushed after each compile in development mode
+  flushAllTraces()
 })

packages/next/build/utils.ts

@@ -31,7 +31,7 @@ import { UnwrapPromise } from '../lib/coalesced-function'
 import { normalizeLocalePath } from '../shared/lib/i18n/normalize-locale-path'
 import * as Log from './output/log'
 import { loadComponents } from '../server/load-components'
-import { trace } from '../telemetry/trace'
+import { trace } from '../trace'
 import { setHttpAgentOptions } from '../server/config'
 import { NextConfigComplete } from '../server/config-shared'