Recompile speedups

README.md

@@ -159,6 +159,13 @@ Accepts a function that will have one argument: an array of eslint messages (obj
 
 Lint only changed files, skip lint on start.
 
+#### `threads`
+
+- Type: `Boolean | Number`
+- Default: `false`
+
+Will run lint tasks across a thread pool. The pool size is automatic unless you specify a number.
+
 ### Errors and Warning
 
 **By default the plugin will auto adjust error reporting depending on eslint errors/warnings counts.**

declarations/utils.d.ts

@@ -18,3 +18,4 @@ export function parseFoldersToGlobs(
   patterns: string | string[],
   extensions?: string | string[]
 ): string[];
+export function jsonStringifyReplacerSortKeys(_: string, value: any): any;

src/getESLint.js

@@ -3,6 +3,10 @@ import os from 'os';
 import JestWorker from 'jest-worker';
 
 import { getESLintOptions } from './options';
+import { jsonStringifyReplacerSortKeys } from './utils';
+
+/** @type {{[key: string]: any}} */
+const cache = {};
 
 /** @typedef {import('eslint').ESLint} ESLint */
 /** @typedef {import('eslint').ESLint.LintResult} LintResult */
@@ -47,6 +51,7 @@ export function loadESLint(options) {
  * @returns {Linter}
  */
 export function loadESLintThreaded(poolSize, options) {
+  const key = getCacheKey(options);
   const { eslintPath = 'eslint' } = options;
   const source = require.resolve('./worker');
   const workerOptions = {
@@ -57,18 +62,28 @@ export function loadESLintThreaded(poolSize, options) {
 
   const local = loadESLint(options);
 
-  /** @type {Worker} */
+  /** @type {Worker?} */
   // prettier-ignore
-  const worker = (/** @type {Worker} */ new JestWorker(source, workerOptions));
+  let worker = (/** @type {Worker} */ new JestWorker(source, workerOptions));
 
-  return {
+  /** @type {Linter} */
+  const context = {
     ...local,
     threads: poolSize,
-    lintFiles: (files) => worker.lintFiles(files),
+    lintFiles: async (files) =>
+      (worker && (await worker.lintFiles(files))) ||
+      /* istanbul ignore next */ [],
     cleanup: async () => {
-      worker.end();
+      cache[key] = local;
+      context.lintFiles = (files) => local.lintFiles(files);
+      if (worker) {
+        worker.end();
+        worker = null;
+      }
     },
   };
+
+  return context;
 }
 
 /**
@@ -84,5 +99,18 @@ export default function getESLint({ threads, ...options }) {
       : /* istanbul ignore next */
         threads;
 
-  return max > 1 ? loadESLintThreaded(max, options) : loadESLint(options);
+  const key = getCacheKey({ threads, ...options });
+  if (!cache[key]) {
+    cache[key] =
+      max > 1 ? loadESLintThreaded(max, options) : loadESLint(options);
+  }
+  return cache[key];
+}
+
+/**
+ * @param {Options} options
+ * @returns {string}
+ */
+function getCacheKey(options) {
+  return JSON.stringify(options, jsonStringifyReplacerSortKeys);
 }

src/options.js

@@ -47,7 +47,6 @@ import schema from './options.json';
 export function getOptions(pluginOptions) {
   const options = {
     extensions: 'js',
-    threads: true,
     ...pluginOptions,
   };
 

src/options.json

@@ -77,7 +77,7 @@
       ]
     },
     "threads": {
-      "description": "Set to true to auto-selected based on number of cpus. Set to a number greater than 1 to set an explicit maximum. Set to false, 1 or less to disable and only run in main process.",
+      "description": "Default is false. Set to true for an auto-selected pool size based on number of cpus. Set to a number greater than 1 to set an explicit pool size. Set to false, 1, or less to disable and only run in main process.",
       "anyOf": [{ "type": "number" }, { "type": "boolean" }]
     }
   }

src/utils.js

@@ -60,3 +60,24 @@ export function parseFoldersToGlobs(patterns, extensions = []) {
       return pattern;
     });
 }
+
+/**
+ *
+ * @param {string} _ key, but unused
+ * @param {any} value
+ */
+export const jsonStringifyReplacerSortKeys = (_, value) => {
+  /**
+   * @param {{ [x: string]: any; }} sorted
+   * @param {string | number} key
+   */
+  const insert = (sorted, key) => {
+    // eslint-disable-next-line no-param-reassign
+    sorted[key] = value[key];
+    return sorted;
+  };
+
+  return value instanceof Object && !(value instanceof Array)
+    ? Object.keys(value).sort().reduce(insert, {})
+    : value;
+};

test/utils/conf.js

@@ -18,6 +18,8 @@ export default (entry, pluginConf = {}, webpackConf = {}) => {
         // folder to skip it on the global linting, but here we want the opposite
         // (we only use .eslintignore on the test that checks this)
         ignore: false,
+        // TODO: update tests to run both states: test.each([[{threads: false}], [{threads: true}]])('it should...', async ({threads}) => {...})
+        threads: true,
         ...pluginConf,
       }),
     ],