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sizebot: Combine stable and experimental results
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Because we have access to the artifacts in CI, we can read bundle sizes
directly from the filesystem, instead of the JSON files emitted by our
custom Rollup plugin.

This gives us some flexibility if we ever have artifacts that aren't
generated by Rollup, or if we rewrite our build script.

Personally, I also prefer to see the whole file path, instead of just
the name, because some of our names are repeated.

My immediate motivation, though, is because it gives us a way to merge
the separate "experimental" and "stable" size results. Instead
everything is reported in a single table and disambiguated by path.

I also added a section at the top that always displays the size impact
to certain critical bundles — right now, that's the React DOM production
bundles for each release channel. This section will also include any
size changes larger than 2%.

Below that is a section that is collapsed by default and includes all
size changes larger than 0.2%.
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@acdlite
acdlite committed Feb 6, 2021
1 parent 903384a commit 6e9473e
Showing 1 changed file with 179 additions and 174 deletions.
353 changes: 179 additions & 174 deletions dangerfile.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@

'use strict';

/* eslint-disable no-for-of-loops/no-for-of-loops */

// Hi, if this is your first time editing/reading a Dangerfile, here's a summary:
// It's a JS runtime which helps you provide continuous feedback inside GitHub.
//
Expand All @@ -26,169 +28,65 @@
// `DANGER_GITHUB_API_TOKEN=[ENV_ABOVE] yarn danger pr https://github.com/facebook/react/pull/11865

const {markdown, danger, warn} = require('danger');

const {generateResultsArray} = require('./scripts/rollup/stats');
const {readFileSync, readdirSync} = require('fs');
const path = require('path');

/**
* Generates a Markdown table
* @param {string[]} headers
* @param {string[][]} body
*/
function generateMDTable(headers, body) {
const tableHeaders = [
headers.join(' | '),
headers.map(() => ' --- ').join(' | '),
];

const tablebody = body.map(r => r.join(' | '));
return tableHeaders.join('\n') + '\n' + tablebody.join('\n');
const {promisify} = require('util');
const glob = promisify(require('glob'));
const gzipSize = require('gzip-size');

const {readFileSync, statSync} = require('fs');

const BASE_DIR = 'base-build';
const HEAD_DIR = 'build2';

const CRITICAL_THRESHOLD = 0.02;
const SIGNIFICANCE_THRESHOLD = 0.002;
const CRITICAL_ARTIFACT_PATHS = new Set([
// We always report changes to these bundles, even if the change is
// insiginificant or non-existent.
'oss-stable/react-dom/cjs/react-dom.production.min.js',
'oss-experimental/react-dom/cjs/react-dom.production.min.js',
'facebook-www/ReactDOM-prod.classic.js',
'facebook-www/ReactDOM-prod.modern.js',
'facebook-www/ReactDOMForked-prod.classic.js',
]);

const kilobyteFormatter = new Intl.NumberFormat('en', {
style: 'unit',
unit: 'kilobyte',
minimumFractionDigits: 2,
maximumFractionDigits: 2,
});

function kbs(bytes) {
return kilobyteFormatter.format(bytes / 1000);
}

/**
* Generates a user-readable string from a percentage change
* @param {number} change
* @param {boolean} includeEmoji
*/
function addPercent(change, includeEmoji) {
if (!isFinite(change)) {
// When a new package is created
return 'n/a';
}
const formatted = (change * 100).toFixed(1);
if (/^-|^0(?:\.0+)$/.test(formatted)) {
return `${formatted}%`;
} else {
if (includeEmoji) {
return `:small_red_triangle:+${formatted}%`;
} else {
return `+${formatted}%`;
}
}
}
const percentFormatter = new Intl.NumberFormat('en', {
style: 'percent',
signDisplay: 'exceptZero',
minimumFractionDigits: 2,
maximumFractionDigits: 2,
});

function setBoldness(row, isBold) {
if (isBold) {
return row.map(element => `**${element}**`);
} else {
return row;
function change(decimal) {
if (Number === Infinity) {
return 'New file';
}
}

function getBundleSizes(pathToSizesDir) {
const filenames = readdirSync(pathToSizesDir);
let bundleSizes = [];
for (let i = 0; i < filenames.length; i++) {
const filename = filenames[i];
if (filename.endsWith('.json')) {
const json = readFileSync(path.join(pathToSizesDir, filename));
bundleSizes.push(...JSON.parse(json).bundleSizes);
}
if (decimal === -1) {
return 'Deleted';
}
if (decimal < 0.0001) {
return '=';
}
return {bundleSizes};
return percentFormatter.format(decimal);
}

async function printResultsForChannel(baseResults, headResults) {
// Take the JSON of the build response and
// make an array comparing the results for printing
const results = generateResultsArray(headResults, baseResults);

const packagesToShow = results
.filter(
r =>
Math.abs(r.prevFileSizeAbsoluteChange) >= 300 || // bytes
Math.abs(r.prevGzipSizeAbsoluteChange) >= 100 // bytes
)
.map(r => r.packageName);

if (packagesToShow.length) {
let allTables = [];

// Highlight React and React DOM changes inline
// e.g. react: `react.production.min.js`: -3%, `react.development.js`: +4%

if (packagesToShow.includes('react')) {
const reactProd = results.find(
r => r.bundleType === 'UMD_PROD' && r.packageName === 'react'
);
if (
reactProd.prevFileSizeChange !== 0 ||
reactProd.prevGzipSizeChange !== 0
) {
const changeSize = addPercent(reactProd.prevFileSizeChange, true);
const changeGzip = addPercent(reactProd.prevGzipSizeChange, true);
markdown(`React: size: ${changeSize}, gzip: ${changeGzip}`);
}
}

if (packagesToShow.includes('react-dom')) {
const reactDOMProd = results.find(
r => r.bundleType === 'UMD_PROD' && r.packageName === 'react-dom'
);
if (
reactDOMProd.prevFileSizeChange !== 0 ||
reactDOMProd.prevGzipSizeChange !== 0
) {
const changeSize = addPercent(reactDOMProd.prevFileSizeChange, true);
const changeGzip = addPercent(reactDOMProd.prevGzipSizeChange, true);
markdown(`ReactDOM: size: ${changeSize}, gzip: ${changeGzip}`);
}
}

// Show a hidden summary table for all diffs

// eslint-disable-next-line no-var,no-for-of-loops/no-for-of-loops
for (var name of new Set(packagesToShow)) {
const thisBundleResults = results.filter(r => r.packageName === name);
const changedFiles = thisBundleResults.filter(
r => r.prevFileSizeChange !== 0 || r.prevGzipSizeChange !== 0
);

const mdHeaders = [
'File',
'Filesize Diff',
'Gzip Diff',
'Prev Size',
'Current Size',
'Prev Gzip',
'Current Gzip',
'ENV',
];

const mdRows = changedFiles.map(r => {
const isProd = r.bundleType.includes('PROD');
return setBoldness(
[
r.filename,
addPercent(r.prevFileSizeChange, isProd),
addPercent(r.prevGzipSizeChange, isProd),
r.prevSize,
r.prevFileSize,
r.prevGzip,
r.prevGzipSize,
r.bundleType,
],
isProd
);
});
const header = `
| Name | +/- | Base | Current | +/- gzip | Base gzip | Current gzip |
| ---- | --- | ---- | ------- | -------- | --------- | ------------ |`;

allTables.push(`\n## ${name}`);
allTables.push(generateMDTable(mdHeaders, mdRows));
}

const summary = `
<details>
<summary>Details of bundled changes.</summary>
${allTables.join('\n')}
</details>
`;
return summary;
} else {
return 'No significant bundle size changes to report.';
}
function row(result) {
// prettier-ignore
return `| ${result.path} | **${change(result.change)}** | ${kbs(result.baseSize)} | ${kbs(result.headSize)} | ${change(result.changeGzip)} | ${kbs(result.baseSizeGzip)} | ${kbs(result.headSizeGzip)}`;
}

(async function() {
Expand All @@ -202,21 +100,10 @@ async function printResultsForChannel(baseResults, headResults) {
}

let headSha;
let headSizesStable;
let headSizesExperimental;

let baseSha;
let baseSizesStable;
let baseSizesExperimental;

try {
headSha = (readFileSync('./build2/COMMIT_SHA') + '').trim();
headSizesStable = getBundleSizes('./build2/sizes-stable');
headSizesExperimental = getBundleSizes('./build2/sizes-experimental');

baseSha = (readFileSync('./base-build/COMMIT_SHA') + '').trim();
baseSizesStable = getBundleSizes('./base-build/sizes-stable');
baseSizesExperimental = getBundleSizes('./base-build/sizes-experimental');
headSha = (readFileSync(HEAD_DIR + '/COMMIT_SHA') + '').trim();
baseSha = (readFileSync(BASE_DIR + '/COMMIT_SHA') + '').trim();
} catch {
warn(
"Failed to read build artifacts. It's possible a build configuration " +
Expand All @@ -226,17 +113,135 @@ async function printResultsForChannel(baseResults, headResults) {
return;
}

const resultsMap = new Map();

// Find all the head (current) artifacts paths.
const headArtifactPaths = await glob('**/*.js', {cwd: 'build2'});
for (const artifactPath of headArtifactPaths) {
try {
// This will throw if there's no matching base artifact
const baseSize = statSync(BASE_DIR + '/' + artifactPath).size;
const baseSizeGzip = gzipSize.fileSync(BASE_DIR + '/' + artifactPath);

const headSize = statSync(HEAD_DIR + '/' + artifactPath).size;
const headSizeGzip = gzipSize.fileSync(HEAD_DIR + '/' + artifactPath);
resultsMap.set(artifactPath, {
path: artifactPath,
headSize,
headSizeGzip,
baseSize,
baseSizeGzip,
change: (headSize - baseSize) / baseSize,
changeGzip: (headSizeGzip - baseSizeGzip) / baseSizeGzip,
});
} catch {
// There's no matching base artifact. This is a new file.
const baseSize = 0;
const baseSizeGzip = 0;
const headSize = statSync(HEAD_DIR + '/' + artifactPath).size;
const headSizeGzip = gzipSize.fileSync(HEAD_DIR + '/' + artifactPath);
resultsMap.set(artifactPath, {
path: artifactPath,
headSize,
headSizeGzip,
baseSize,
baseSizeGzip,
change: Infinity,
changeGzip: Infinity,
});
}
}

// Check for base artifacts that were deleted in the head.
const baseArtifactPaths = await glob('**/*.js', {cwd: 'base-build'});
for (const artifactPath of baseArtifactPaths) {
if (!resultsMap.has(artifactPath)) {
const baseSize = statSync(BASE_DIR + '/' + artifactPath).size;
const baseSizeGzip = gzipSize.fileSync(BASE_DIR + '/' + artifactPath);
const headSize = 0;
const headSizeGzip = 0;
resultsMap.set(artifactPath, {
path: artifactPath,
headSize,
headSizeGzip,
baseSize,
baseSizeGzip,
change: -1,
changeGzip: -1,
});
}
}

const results = Array.from(resultsMap.values());
results.sort((a, b) => b.change - a.change);

let criticalResults = [];
for (const artifactPath of CRITICAL_ARTIFACT_PATHS) {
const result = resultsMap.get(artifactPath);
if (result === undefined) {
throw new Error(
'Missing expected bundle. If this was an intentional change to the ' +
'build configuration, update Dangerfile.js accordingly: ' +
artifactPath
);
}
criticalResults.push(row(result));
}

let significantResults = [];
for (const result of results) {
// If result exceeds critical threshold, add to top section.
if (
(result.change > CRITICAL_THRESHOLD ||
0 - result.change > CRITICAL_THRESHOLD ||
// New file
result.change === Infinity ||
// Deleted file
result.change === -1) &&
// Skip critical artifacts. We added those earlier, in a fixed order.
!CRITICAL_ARTIFACT_PATHS.has(result.path)
) {
criticalResults.push(row(result));
}

// Do the same for results that exceed the significant threshold. These
// will go into the bottom, collapsed section. Intentionally including
// critical artifacts in this section, too.
if (
result.change > SIGNIFICANCE_THRESHOLD ||
0 - result.change > SIGNIFICANCE_THRESHOLD ||
result.change === Infinity ||
result.change === -1
) {
significantResults.push(row(result));
}
}

markdown(`
## Size changes
Comparing: ${baseSha}...${headSha}
## Critical size changes
<p>Comparing: ${baseSha}...${headSha}</p>
Includes critical production bundles, as well as any change greater than ${CRITICAL_THRESHOLD *
100}%:
### Stable channel
${header}
${criticalResults.join('\n')}
${await printResultsForChannel(baseSizesStable, headSizesStable)}
## Significant size changes
### Experimental channel
Includes any change greater than ${SIGNIFICANCE_THRESHOLD * 100}%:
${await printResultsForChannel(baseSizesExperimental, headSizesExperimental)}
${
significantResults.length > 0
? `
<details>
<summary>Expand to show</summary>
${header}
${significantResults.join('\n')}
</details>
`
: '(No significant changes)'
}
`);
})();

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