packager: TransformCache: extract choice of root path outside of class

Summary: This is a first step towards doing an experiment I was talking about, that is, using the local directory (the directory where the config file lives) instead of the tmp dir, that is fragile.

Reviewed By: davidaurelio

Differential Revision: D5112326

fbshipit-source-id: 819636209972115e41213867f3eb78fbdf6ed9df

packages/metro-bundler/src/Bundler/__tests__/Bundler-test.js

@@ -34,6 +34,7 @@ var defaults = require('../../../defaults');
 var sizeOf = require('image-size');
 var fs = require('fs');
 const os = require('os');
+const path = require('path');
 
 const {any, objectContaining} = expect;
 
@@ -85,6 +86,9 @@ describe('Bundler', function() {
 
   beforeEach(function() {
     os.cpus.mockReturnValue({length: 1});
+    // local directory on purpose, because it should not actually write
+    // anything to the disk during a unit test!
+    os.tmpDir.mockReturnValue(path.join(__dirname));
 
     getDependencies = jest.fn();
     getModuleSystemDependencies = jest.fn();

packages/metro-bundler/src/lib/TransformCache.js

@@ -15,6 +15,7 @@
 const crypto = require('crypto');
 const debugRead = require('debug')('RNP:TransformCache:Read');
 const fs = require('fs');
+const invariant = require('fbjs/lib/invariant');
 const mkdirp = require('mkdirp');
 const path = require('path');
 const rimraf = require('rimraf');
@@ -29,7 +30,6 @@ import type {LocalPath} from '../node-haste/lib/toLocalPath';
 type CacheFilePaths = {transformedCode: string, metadata: string};
 export type GetTransformCacheKey = (options: {}) => string;
 
-const CACHE_NAME = 'react-native-packager-cache';
 const CACHE_SUB_DIR = 'cache';
 
 export type CachedResult = {
@@ -68,11 +68,25 @@ const CACHE_FILE_MAX_LAST_ACCESS_TIME = GARBAGE_COLLECTION_PERIOD * 4;
 
 class TransformCache {
   _cacheWasReset: boolean;
-  _dirPath: string;
   _lastCollected: ?number;
+  _rootPath: string;
 
-  constructor() {
+  /**
+   * The root path is where the data will be stored. It shouldn't contain
+   * other files other than the cache's own files, so it should start empty
+   * when the packager is first run. When doing a cache reset, it may be
+   * completely deleted.
+   */
+  constructor(rootPath: string) {
     this._cacheWasReset = false;
+    invariant(
+      path.isAbsolute(rootPath),
+      'root path of the transform cache must be absolute',
+    );
+    require('debug')('RNP:TransformCache:Dir')(
+      `transform cache directory: ${rootPath}`,
+    );
+    this._rootPath = rootPath;
   }
 
   /**
@@ -90,16 +104,14 @@ class TransformCache {
    * close to each others, one of the workers is going to loose its results no
    * matter what.
    */
-  writeSync(
-    props: {
-      filePath: string,
-      sourceCode: string,
-      getTransformCacheKey: GetTransformCacheKey,
-      transformOptions: WorkerOptions,
-      transformOptionsKey: string,
-      result: CachedResult,
-    },
-  ): void {
+  writeSync(props: {
+    filePath: string,
+    sourceCode: string,
+    getTransformCacheKey: GetTransformCacheKey,
+    transformOptions: WorkerOptions,
+    transformOptionsKey: string,
+    result: CachedResult,
+  }): void {
     const cacheFilePath = this._getCacheFilePaths(props);
     mkdirp.sync(path.dirname(cacheFilePath.transformedCode));
     const {result} = props;
@@ -202,7 +214,7 @@ class TransformCache {
   }
 
   _resetCache(reporter: Reporter) {
-    rimraf.sync(this._getCacheDirPath());
+    rimraf.sync(this._rootPath);
     reporter.update({type: 'transform_cache_reset'});
     this._cacheWasReset = true;
     this._lastCollected = Date.now();
@@ -220,7 +232,7 @@ class TransformCache {
       terminal.log(
         'Error: Cleaning up the cache folder failed. Continuing anyway.',
       );
-      terminal.log('The cache folder is: %s', this._getCacheDirPath());
+      terminal.log('The cache folder is: %s', this._rootPath);
     }
     this._lastCollected = Date.now();
   }
@@ -231,7 +243,7 @@ class TransformCache {
    * first.
    */
   _collectCacheIfOldSync() {
-    const cacheDirPath = this._getCacheDirPath();
+    const cacheDirPath = this._rootPath;
     mkdirp.sync(cacheDirPath);
     const cacheCollectionFilePath = path.join(cacheDirPath, 'last_collected');
     const lastCollected = Number.parseInt(
@@ -255,12 +267,10 @@ class TransformCache {
    * account because it would generate lots of file during development. (The
    * source hash is stored in the metadata instead).
    */
-  _getCacheFilePaths(
-    props: {
-      filePath: string,
-      transformOptionsKey: string,
-    },
-  ): CacheFilePaths {
+  _getCacheFilePaths(props: {
+    filePath: string,
+    transformOptionsKey: string,
+  }): CacheFilePaths {
     const hasher = crypto
       .createHash('sha1')
       .update(props.filePath)
@@ -268,38 +278,9 @@ class TransformCache {
     const hash = hasher.digest('hex');
     const prefix = hash.substr(0, 2);
     const fileName = `${hash.substr(2)}`;
-    const base = path.join(
-      this._getCacheDirPath(),
-      CACHE_SUB_DIR,
-      prefix,
-      fileName,
-    );
+    const base = path.join(this._rootPath, CACHE_SUB_DIR, prefix, fileName);
     return {transformedCode: base, metadata: base + '.meta'};
   }
-
-  /**
-   * If packager is running for two different directories, we don't want the
-   * caches to conflict with each other. `__dirname` carries that because
-   * packager will be, for example, installed in a different `node_modules/`
-   * folder for different projects.
-   */
-  _getCacheDirPath() {
-    if (this._dirPath != null) {
-      return this._dirPath;
-    }
-    const hash = crypto.createHash('sha1').update(__dirname);
-    if (process.getuid != null) {
-      hash.update(process.getuid().toString());
-    }
-    this._dirPath = path.join(
-      require('os').tmpdir(),
-      CACHE_NAME + '-' + hash.digest('hex'),
-    );
-    require('debug')('RNP:TransformCache:Dir')(
-      `transform cache directory: ${this._dirPath}`,
-    );
-    return this._dirPath;
-  }
 }
 
 /**
@@ -388,15 +369,13 @@ function tryParseJSON(str: string): any {
   }
 }
 
-function hashSourceCode(
-  props: {
-    filePath: string,
-    sourceCode: string,
-    getTransformCacheKey: GetTransformCacheKey,
-    transformOptions: WorkerOptions,
-    transformOptionsKey: string,
-  },
-): string {
+function hashSourceCode(props: {
+  filePath: string,
+  sourceCode: string,
+  getTransformCacheKey: GetTransformCacheKey,
+  transformOptions: WorkerOptions,
+  transformOptionsKey: string,
+}): string {
   return crypto
     .createHash('sha1')
     .update(props.getTransformCacheKey(props.transformOptions))

packages/metro-bundler/src/lib/__tests__/TransformCache-test.js

@@ -55,7 +55,7 @@ describe('TransformCache', () => {
   beforeEach(() => {
     jest.resetModules();
     mockFS.clear();
-    transformCache = new (require('../TransformCache'))();
+    transformCache = new (require('../TransformCache'))('/cache');
   });
 
   it('is caching different files and options separately', () => {

packages/metro-bundler/src/node-haste/Module.js

@@ -20,6 +20,7 @@ const fs = require('fs');
 const invariant = require('fbjs/lib/invariant');
 const isAbsolutePath = require('absolute-path');
 const jsonStableStringify = require('json-stable-stringify');
+const path = require('path');
 
 const {join: joinPath, relative: relativePath, extname} = require('path');
 
@@ -85,8 +86,6 @@ export type ConstructorArgs = {
 
 type DocBlock = {+[key: string]: string};
 
-const TRANSFORM_CACHE = new TransformCache();
-
 class Module {
   localPath: LocalPath;
   path: string;
@@ -107,6 +106,8 @@ class Module {
 
   _readResultsByOptionsKey: Map<string, CachedReadResult>;
 
+  static _transformCache: TransformCache;
+
   constructor({
     depGraphHelpers,
     localPath,
@@ -333,7 +334,7 @@ class Module {
         return;
       }
       invariant(result != null, 'missing result');
-      TRANSFORM_CACHE.writeSync({...cacheProps, result});
+      Module._getTransformCache().writeSync({...cacheProps, result});
       callback(undefined, result);
     });
   }
@@ -380,7 +381,7 @@ class Module {
       transformOptions,
       transformOptionsKey,
     );
-    const cachedResult = TRANSFORM_CACHE.readSync(cacheProps);
+    const cachedResult = Module._getTransformCache().readSync(cacheProps);
     if (cachedResult.result == null) {
       return {
         result: null,
@@ -468,6 +469,27 @@ class Module {
   isPolyfill() {
     return false;
   }
+
+  /**
+   * If packager is running for two different directories, we don't want the
+   * caches to conflict with each other. `__dirname` carries that because
+   * packager will be, for example, installed in a different `node_modules/`
+   * folder for different projects.
+   */
+  static _getTransformCache(): TransformCache {
+    if (this._transformCache != null) {
+      return this._transformCache;
+    }
+    const hash = crypto.createHash('sha1').update(__dirname);
+    if (process.getuid != null) {
+      hash.update(process.getuid().toString());
+    }
+    const tmpDir = require('os').tmpdir();
+    const cacheName = 'react-native-packager-cache';
+    const rootPath = path.join(tmpDir, cacheName + '-' + hash.digest('hex'));
+    this._transformCache = new TransformCache(rootPath);
+    return this._transformCache;
+  }
 }
 
 // use weak map to speed up hash creation of known objects