Run Prettier serially

This doesn't appear to significantly change the execution time based on
some very rudimentary testing.

.changeset/pretty-kings-exist.md

@@ -0,0 +1,7 @@
+---
+"skuba": patch
+---
+
+format, lint: Run Prettier serially on files
+
+This aims to reduce the memory footprint of `skuba lint`.

package.json

@@ -80,7 +80,6 @@
     "normalize-package-data": "^3.0.0",
     "npm-run-path": "^4.0.1",
     "npm-which": "^3.0.1",
-    "p-limit": "3.1.0",
     "picomatch": "^2.2.2",
     "prettier": "2.4.1",
     "read-pkg-up": "^7.0.1",

src/cli/__snapshots__/format.int.test.ts.snap

@@ -63,7 +63,6 @@ Initialising Prettier...
 Detected project root: <random>
 Discovering files...
 Discovered 6 files.
-Reading files...
 Formatting files...
 b.md
   parser: markdown
@@ -77,7 +76,6 @@ tsconfig.json
   parser: json
 a/a/a.ts
   parser: typescript
-Writing 0 files...
 Processed 6 files in <random>s.
 "
 `;

src/cli/__snapshots__/lint.int.test.ts.snap

@@ -65,7 +65,6 @@ Prettier │ Initialising Prettier...
 Prettier │ Detected project root: <random>
 Prettier │ Discovering files...
 Prettier │ Discovered 6 files.
-Prettier │ Reading files...
 Prettier │ Linting files...
 Prettier │ b.md
 Prettier │   parser: markdown
@@ -79,7 +78,6 @@ Prettier │ tsconfig.json
 Prettier │   parser: json
 Prettier │ a/a/a.ts
 Prettier │   parser: typescript
-Prettier │ Writing 0 files...
 Prettier │ Processed 6 files in <random>s.
 tsc      │ TSFILE: <random>/lib/tsconfig.tsbuildinfo
 tsc      │ Files: <random>

src/cli/adapter/prettier.ts

@@ -1,15 +1,12 @@
 import path from 'path';
 
 import fs from 'fs-extra';
-import pLimit from 'p-limit';
 import { Options, check, format, getFileInfo, resolveConfig } from 'prettier';
 
 import { crawlDirectory } from '../../utils/dir';
 import { Logger } from '../../utils/logging';
 import { getConsumerManifest } from '../../utils/manifest';
 
-const fsLimit = pLimit(25);
-
 interface File {
   data: string;
   options: Options;
@@ -20,7 +17,7 @@ interface File {
 interface Result {
   count: number;
   errored: Array<{ err?: unknown; filepath: string }>;
-  touched: Array<{ data: string; filepath: string }>;
+  touched: string[];
   unparsed: string[];
 }
 
@@ -29,7 +26,7 @@ const formatOrLintFile = (
   logger: Logger,
   mode: 'format' | 'lint',
   result: Result,
-) => {
+): string | undefined => {
   logger.debug(filepath);
 
   logger.debug('  parser:', parser ?? '-');
@@ -67,7 +64,8 @@ const formatOrLintFile = (
     return;
   }
 
-  result.touched.push({ data: formatted, filepath });
+  result.touched.push(filepath);
+  return formatted;
 };
 
 export interface PrettierOutput {
@@ -119,40 +117,30 @@ export const runPrettier = async (
     unparsed: [],
   };
 
-  logger.debug('Reading files...');
-
-  const files = await Promise.all(
-    filepaths.map<Promise<File>>(async (filepath) => {
-      const [config, data, fileInfo] = await Promise.all([
-        fsLimit(() => resolveConfig(filepath)),
-        fsLimit(() => fs.promises.readFile(filepath, 'utf-8')),
-        // Infer parser upfront so we can know to ignore unsupported file types.
-        fsLimit(() => getFileInfo(filepath, { resolveConfig: false })),
-      ]);
-
-      return {
-        data,
-        filepath,
-        options: { ...config, filepath },
-        parser: fileInfo.inferredParser,
-      };
-    }),
-  );
-
   logger.debug(mode === 'format' ? 'Formatting' : 'Linting', 'files...');
 
-  for (const file of files) {
-    formatOrLintFile(file, logger, mode, result);
+  for (const filepath of filepaths) {
+    const [config, data, fileInfo] = await Promise.all([
+      resolveConfig(filepath),
+      fs.promises.readFile(filepath, 'utf-8'),
+      // Infer parser upfront so we can know to ignore unsupported file types.
+      getFileInfo(filepath, { resolveConfig: false }),
+    ]);
+
+    const file: File = {
+      data,
+      filepath,
+      options: { ...config, filepath },
+      parser: fileInfo.inferredParser,
+    };
+
+    const formatted = formatOrLintFile(file, logger, mode, result);
+
+    if (typeof formatted === 'string') {
+      await fs.promises.writeFile(filepath, formatted);
+    }
   }
 
-  logger.debug(`Writing ${logger.pluralise(result.touched.length, 'file')}...`);
-
-  await Promise.all(
-    result.touched.map(({ data, filepath }) =>
-      fsLimit(() => fs.promises.writeFile(filepath, data)),
-    ),
-  );
-
   const end = process.hrtime.bigint();
 
   logger.plain(
@@ -166,7 +154,7 @@ export const runPrettier = async (
     logger.plain(
       `Formatted ${logger.pluralise(result.touched.length, 'file')}:`,
     );
-    for (const { filepath } of result.touched) {
+    for (const filepath of result.touched) {
       logger.warn(filepath);
     }
   }

yarn.lock

@@ -6296,13 +6296,6 @@ p-is-promise@^3.0.0:
   resolved "https://registry.yarnpkg.com/p-is-promise/-/p-is-promise-3.0.0.tgz#58e78c7dfe2e163cf2a04ff869e7c1dba64a5971"
   integrity sha512-Wo8VsW4IRQSKVXsJCn7TomUaVtyfjVDn3nUP7kE967BQk0CwFpdbZs0X0uk5sW9mkBa9eNM7hCMaG93WUAwxYQ==
 
-[email protected], p-limit@^3.0.2:
-  version "3.1.0"
-  resolved "https://registry.yarnpkg.com/p-limit/-/p-limit-3.1.0.tgz#e1daccbe78d0d1388ca18c64fea38e3e57e3706b"
-  integrity sha512-TYOanM3wGwNGsZN2cVTYPArw454xnXj5qmWF1bEoAc4+cU/ol7GVh7odevjp1FNHduHc3KZMcFduxU5Xc6uJRQ==
-  dependencies:
-    yocto-queue "^0.1.0"
-
 p-limit@^1.1.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/p-limit/-/p-limit-1.3.0.tgz#b86bd5f0c25690911c7590fcbfc2010d54b3ccb8"
@@ -6317,6 +6310,13 @@ p-limit@^2.2.0:
   dependencies:
     p-try "^2.0.0"
 
+p-limit@^3.0.2:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/p-limit/-/p-limit-3.1.0.tgz#e1daccbe78d0d1388ca18c64fea38e3e57e3706b"
+  integrity sha512-TYOanM3wGwNGsZN2cVTYPArw454xnXj5qmWF1bEoAc4+cU/ol7GVh7odevjp1FNHduHc3KZMcFduxU5Xc6uJRQ==
+  dependencies:
+    yocto-queue "^0.1.0"
+
 p-locate@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/p-locate/-/p-locate-2.0.0.tgz#20a0103b222a70c8fd39cc2e580680f3dde5ec43"