fix: compatibility with webpack@5

package.json

@@ -49,9 +49,9 @@
   },
   "devDependencies": {
     "@babel/cli": "^7.10.5",
-    "@babel/core": "^7.11.1",
+    "@babel/core": "^7.11.4",
     "@babel/preset-env": "^7.11.0",
-    "@commitlint/cli": "^9.1.2",
+    "@commitlint/cli": "^10.0.0",
     "@commitlint/config-conventional": "^10.0.0",
     "@gfx/zopfli": "^1.0.15",
     "@webpack-contrib/defaults": "^6.3.0",
@@ -65,7 +65,7 @@
     "eslint-plugin-import": "^2.22.0",
     "file-loader": "^6.0.0",
     "husky": "^4.2.5",
-    "jest": "^26.4.0",
+    "jest": "^26.4.1",
     "lint-staged": "^10.2.11",
     "memfs": "^3.2.0",
     "npm-run-all": "^4.1.5",

src/Webpack4Cache.js

@@ -5,42 +5,59 @@ import findCacheDir from 'find-cache-dir';
 import serialize from 'serialize-javascript';
 
 export default class Webpack4Cache {
-  constructor(compilation, options) {
-    this.cacheDir =
+  constructor(compilation, options, weakCache) {
+    this.cache =
       options.cache === true
         ? Webpack4Cache.getCacheDirectory()
         : options.cache;
+    this.weakCache = weakCache;
   }
 
   static getCacheDirectory() {
     return findCacheDir({ name: 'compression-webpack-plugin' }) || os.tmpdir();
   }
 
-  isEnabled() {
-    return Boolean(this.cacheDir);
-  }
+  async get(task, sources) {
+    const weakOutput = this.weakCache.get(task.assetSource);
+
+    if (weakOutput) {
+      return weakOutput;
+    }
+
+    if (!this.cache) {
+      // eslint-disable-next-line no-undefined
+      return undefined;
+    }
 
-  async get(task) {
     // eslint-disable-next-line no-param-reassign
     task.cacheIdent = task.cacheIdent || serialize(task.cacheKeys);
 
     let cachedResult;
 
     try {
-      cachedResult = await cacache.get(this.cacheDir, task.cacheIdent);
+      cachedResult = await cacache.get(this.cache, task.cacheIdent);
     } catch (ignoreError) {
       // eslint-disable-next-line no-undefined
       return undefined;
     }
 
-    return Buffer.from(JSON.parse(cachedResult.data).data);
+    return new sources.RawSource(
+      Buffer.from(JSON.parse(cachedResult.data).data)
+    );
   }
 
   async store(task) {
-    return cacache.put(
-      this.cacheDir,
-      task.cacheIdent,
-      JSON.stringify(task.output)
-    );
+    if (!this.weakCache.has(task.assetSource)) {
+      this.weakCache.set(task.assetSource, task.output);
+    }
+
+    if (!this.cache) {
+      // eslint-disable-next-line no-undefined
+      return undefined;
+    }
+
+    const { cacheIdent, output } = task;
+
+    return cacache.put(this.cache, cacheIdent, JSON.stringify(output.source()));
   }
 }

src/Webpack5Cache.js

@@ -1,14 +1,8 @@
 export default class Cache {
-  // eslint-disable-next-line no-unused-vars
-  constructor(compilation, ignored) {
+  constructor(compilation) {
     this.cache = compilation.getCache('CompressionWebpackPlugin');
   }
 
-  // eslint-disable-next-line class-methods-use-this
-  isEnabled() {
-    return true;
-  }
-
   async get(task) {
     // eslint-disable-next-line no-param-reassign
     task.eTag = task.eTag || this.cache.getLazyHashedEtag(task.assetSource);

src/index.js

@@ -7,12 +7,18 @@ import crypto from 'crypto';
 import url from 'url';
 import path from 'path';
 
-import RawSource from 'webpack-sources/lib/RawSource';
-import { ModuleFilenameHelpers, version as webpackVersion } from 'webpack';
+import webpack, {
+  ModuleFilenameHelpers,
+  version as webpackVersion,
+} from 'webpack';
 import validateOptions from 'schema-utils';
 
 import schema from './options.json';
 
+const { RawSource } =
+  // eslint-disable-next-line global-require
+  webpack.sources || require('webpack-sources');
+
 class CompressionPlugin {
   constructor(options = {}) {
     validateOptions(schema, options, {
@@ -203,29 +209,20 @@ class CompressionPlugin {
     yield task;
   }
 
-  afterTask(compilation, task, weakCache) {
+  afterTask(compilation, task) {
     const { output, input } = task;
 
-    if (output.length / input.length > this.options.minRatio) {
+    if (output.source().length / input.length > this.options.minRatio) {
       return;
     }
 
     const { assetSource, assetName } = task;
-
-    let weakOutput = weakCache.get(assetSource);
-
-    if (!weakOutput) {
-      weakOutput = new RawSource(output);
-
-      weakCache.set(assetSource, weakOutput);
-    }
-
     const newAssetName = CompressionPlugin.interpolateName(
       assetName,
       this.options.filename
     );
 
-    CompressionPlugin.emitAsset(compilation, newAssetName, weakOutput, {
+    CompressionPlugin.emitAsset(compilation, newAssetName, output, {
       compressed: true,
     });
 
@@ -241,28 +238,15 @@ class CompressionPlugin {
 
   async runTasks(compilation, assetNames, CacheEngine, weakCache) {
     const scheduledTasks = [];
-    const cache = new CacheEngine(compilation, {
-      cache: this.options.cache,
-    });
+    const cache = new CacheEngine(
+      compilation,
+      {
+        cache: this.options.cache,
+      },
+      weakCache
+    );
 
     for (const assetName of assetNames) {
-      const enqueue = async (task) => {
-        try {
-          // eslint-disable-next-line no-param-reassign
-          task.output = await this.compress(task.input);
-        } catch (error) {
-          compilation.errors.push(error);
-
-          return;
-        }
-
-        if (cache.isEnabled()) {
-          await cache.store(task);
-        }
-
-        this.afterTask(compilation, task, weakCache);
-      };
-
       scheduledTasks.push(
         (async () => {
           const task = this.getTask(compilation, assetName).next().value;
@@ -271,23 +255,24 @@ class CompressionPlugin {
             return Promise.resolve();
           }
 
-          if (cache.isEnabled()) {
+          task.output = await cache.get(task, { RawSource });
+
+          if (!task.output) {
             try {
-              task.output = await cache.get(task);
-            } catch (ignoreError) {
-              return enqueue(task);
-            }
+              // eslint-disable-next-line no-param-reassign
+              task.output = new RawSource(await this.compress(task.input));
+            } catch (error) {
+              compilation.errors.push(error);
 
-            if (!task.output) {
-              return enqueue(task);
+              return Promise.resolve();
             }
 
-            this.afterTask(compilation, task, weakCache);
-
-            return Promise.resolve();
+            await cache.store(task);
           }
 
-          return enqueue(task);
+          this.afterTask(compilation, task);
+
+          return Promise.resolve();
         })()
       );
     }
@@ -306,8 +291,12 @@ class CompressionPlugin {
       undefined,
       this.options
     );
-    const weakCache = new WeakMap();
-    const compressionFn = async (compilation, CacheEngine, assets) => {
+    const compressionFn = async (
+      compilation,
+      assets,
+      CacheEngine,
+      weakCache
+    ) => {
       const assetNames = Object.keys(
         typeof assets === 'undefined' ? compilation.assets : assets
       ).filter((assetName) => matchObject(assetName));
@@ -324,11 +313,11 @@ class CompressionPlugin {
     if (CompressionPlugin.isWebpack4()) {
       // eslint-disable-next-line global-require
       const CacheEngine = require('./Webpack4Cache').default;
+      const weakCache = new WeakMap();
 
-      compiler.hooks.emit.tapPromise(
-        { name: pluginName },
+      compiler.hooks.emit.tapPromise({ name: pluginName }, (compilation) =>
         // eslint-disable-next-line no-undefined
-        (compilation) => compressionFn(compilation, CacheEngine)
+        compressionFn(compilation, undefined, CacheEngine, weakCache)
       );
     } else {
       // eslint-disable-next-line global-require
@@ -343,7 +332,7 @@ class CompressionPlugin {
             name: pluginName,
             stage: Compilation.PROCESS_ASSETS_STAGE_OPTIMIZE_TRANSFER,
           },
-          (assets) => compressionFn(compilation, CacheEngine, assets)
+          (assets) => compressionFn(compilation, assets, CacheEngine)
         );
 
         compilation.hooks.statsPrinter.tap(pluginName, (stats) => {

test/CompressionPlugin.test.js

@@ -213,4 +213,34 @@ describe('CompressionPlugin', () => {
       resolve();
     });
   });
+
+  it('should work in watch mode when "cache" is "false"', async () => {
+    if (getCompiler.isWebpack4()) {
+      expect(true).toBe(true);
+    } else {
+      const compiler = getCompiler('./entry.js', {
+        cache: false,
+      });
+
+      new CompressionPlugin().apply(compiler);
+
+      const stats = await compile(compiler);
+
+      expect(stats.compilation.emittedAssets.size).toBe(7);
+      expect(getAssetsNameAndSize(stats)).toMatchSnapshot('assets');
+      expect(getWarnings(stats)).toMatchSnapshot('errors');
+      expect(getErrors(stats)).toMatchSnapshot('warnings');
+
+      await new Promise(async (resolve) => {
+        const newStats = await compile(compiler);
+
+        expect(newStats.compilation.emittedAssets.size).toBe(0);
+        expect(getAssetsNameAndSize(newStats)).toMatchSnapshot('assets');
+        expect(getWarnings(newStats)).toMatchSnapshot('errors');
+        expect(getErrors(newStats)).toMatchSnapshot('warnings');
+
+        resolve();
+      });
+    }
+  });
 });