feat: support webpack@5 cache

README.md

@@ -141,6 +141,8 @@ module.exports = {
 
 ### `cache`
 
+> ⚠ Doesn't work with webpack 5!
+
 Type: `Boolean|String`
 Default: `true`
 
@@ -189,6 +191,8 @@ module.exports = {
 
 ### `cacheKeys`
 
+> ⚠ Doesn't work with webpack 5!
+
 Type: `Function<(defaultCacheKeys, file) -> Object>`
 Default: `defaultCacheKeys => defaultCacheKeys`
 
@@ -491,6 +495,8 @@ module.exports = {
         extractComments: {
           condition: /^\**!|@preserve|@license|@cc_on/i,
           filename: (file, fileData) => {
+            // ⚠ webpack 5: there is only fileData parameter
+
             // A file can contain a query string (for example when you have `output.filename: '[name].js?[chunkhash]'`)
             // You must consider this
             // The "fileData" argument contains object with "filename", "basename", "query"
@@ -523,6 +529,8 @@ module.exports = {
         extractComments: {
           condition: 'some',
           filename: (file, fileData) => {
+            // ⚠ webpack 5: there is only fileData parameter
+
             // A file can contain a query string (for example when you have `output.filename: '[name].js?[chunkhash]'`)
             // You must consider this
             return file.replace(/\.(\w+)($|\?)/, '.$1.LICENSE$2');
@@ -542,7 +550,7 @@ module.exports = {
 Type: `String|Function<(string) -> String>`
 Default: `[file].LICENSE[query]`
 
-Available placeholders: `[file]`, `[query]` and `[filebase]`.
+Available placeholders: `[file]`, `[query]` and `[filebase]` (`[base]` for webpack 5).
 
 The file where the extracted comments will be stored.
 Default is to append the suffix `.LICENSE` to the original filename.
@@ -588,6 +596,8 @@ module.exports = {
         extractComments: {
           condition: true,
           filename: (file, fileData) => {
+            // ⚠ webpack 5: there is only fileData parameter
+
             // A file can contain a query string (for example when you have `output.filename: '[name].js?[chunkhash]'`)
             // You must consider this
             return file.replace(/\.(\w+)($|\?)/, '.$1.LICENSE$2');

src/TaskRunner.js

@@ -1,7 +1,5 @@
 import os from 'os';
 
-import cacache from 'cacache';
-import findCacheDir from 'find-cache-dir';
 import Worker from 'jest-worker';
 import serialize from 'serialize-javascript';
 
@@ -11,15 +9,8 @@ const workerPath = require.resolve('./worker');
 
 export default class TaskRunner {
   constructor(options = {}) {
-    this.options = options;
-    this.cacheDir = TaskRunner.getCacheDirectory(this.options.cache);
-    this.numberWorkers = TaskRunner.getNumberWorkers(this.options.parallel);
-  }
-
-  static getCacheDirectory(cache) {
-    return cache === true
-      ? findCacheDir({ name: 'terser-webpack-plugin' }) || os.tmpdir()
-      : cache;
+    this.cache = options.cache;
+    this.numberWorkers = TaskRunner.getNumberWorkers(options.parallel);
   }
 
   static getNumberWorkers(parallel) {
@@ -56,26 +47,18 @@ export default class TaskRunner {
             result = { error };
           }
 
-          if (this.cacheDir && !result.error) {
-            return cacache
-              .put(
-                this.cacheDir,
-                serialize(task.cacheKeys),
-                JSON.stringify(result)
-              )
-              .then(
-                () => result,
-                () => result
-              );
+          if (this.cache.isEnabled() && !result.error) {
+            return this.cache.store(task, result).then(
+              () => result,
+              () => result
+            );
           }
 
           return result;
         };
 
-        if (this.cacheDir) {
-          return cacache
-            .get(this.cacheDir, serialize(task.cacheKeys))
-            .then(({ data }) => JSON.parse(data), enqueue);
+        if (this.cache.isEnabled()) {
+          return this.cache.get(task).then((data) => data, enqueue);
         }
 
         return enqueue();

src/Webpack4Cache.js

@@ -0,0 +1,36 @@
+import os from 'os';
+
+import cacache from 'cacache';
+import findCacheDir from 'find-cache-dir';
+import serialize from 'serialize-javascript';
+
+export default class Webpack4Cache {
+  constructor(compilation, options) {
+    this.options = options;
+    this.cacheDir =
+      options.cache === true
+        ? Webpack4Cache.getCacheDirectory()
+        : options.cache;
+  }
+
+  static getCacheDirectory() {
+    return findCacheDir({ name: 'terser-webpack-plugin' }) || os.tmpdir();
+  }
+
+  isEnabled() {
+    return !!this.cacheDir;
+  }
+
+  get(task) {
+    // eslint-disable-next-line no-param-reassign
+    task.cacheIdent = task.cacheIdent || serialize(task.cacheKeys);
+
+    return cacache
+      .get(this.cacheDir, task.cacheIdent)
+      .then(({ data }) => JSON.parse(data));
+  }
+
+  store(task, data) {
+    return cacache.put(this.cacheDir, task.cacheIdent, JSON.stringify(data));
+  }
+}

src/Webpack5Cache.js

@@ -0,0 +1,65 @@
+import crypto from 'crypto';
+
+// eslint-disable-next-line import/extensions,import/no-unresolved
+import getLazyHashedEtag from 'webpack/lib/cache/getLazyHashedEtag';
+import serialize from 'serialize-javascript';
+
+export default class Cache {
+  constructor(compilation, options) {
+    this.options = options;
+    this.compilation = compilation;
+  }
+
+  isEnabled() {
+    return !!this.compilation.cache;
+  }
+
+  createCacheIdent(task) {
+    const cacheKeys = crypto
+      .createHash('md4')
+      .update(serialize(task.cacheKeys))
+      .digest('hex');
+
+    return `${this.compilation.compilerPath}/TerserWebpackPlugin/${cacheKeys}/${task.file}`;
+  }
+
+  get(task) {
+    // eslint-disable-next-line no-param-reassign
+    task.cacheIdent = task.cacheIdent || this.createCacheIdent(task);
+    // eslint-disable-next-line no-param-reassign
+    task.cacheETag = task.cacheETag || getLazyHashedEtag(task.asset);
+
+    return new Promise((resolve, reject) => {
+      this.compilation.cache.get(
+        task.cacheIdent,
+        task.cacheETag,
+        (err, result) => {
+          if (err) {
+            reject(err);
+          } else if (result) {
+            resolve(result);
+          } else {
+            reject();
+          }
+        }
+      );
+    });
+  }
+
+  store(task, data) {
+    return new Promise((resolve, reject) => {
+      this.compilation.cache.store(
+        task.cacheIdent,
+        task.cacheETag,
+        data,
+        (err) => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(data);
+          }
+        }
+      );
+    });
+  }
+}

src/index.js

@@ -8,6 +8,7 @@ import {
   ModuleFilenameHelpers,
   SourceMapDevToolPlugin,
   javascript,
+  version as webpackVersion,
 } from 'webpack';
 import validateOptions from 'schema-utils';
 import serialize from 'serialize-javascript';
@@ -192,6 +193,10 @@ class TerserPlugin {
     );
   }
 
+  static isWebpack4() {
+    return webpackVersion[0] === '4';
+  }
+
   apply(compiler) {
     const { devtool, output, plugins } = compiler.options;
 
@@ -288,9 +293,11 @@ class TerserPlugin {
             commentsFilename =
               this.options.extractComments.filename || '[file].LICENSE[query]';
 
-            // Todo remove this in next major release
-            if (typeof commentsFilename === 'function') {
-              commentsFilename = commentsFilename.bind(null, file);
+            if (TerserPlugin.isWebpack4()) {
+              // Todo remove this in next major release
+              if (typeof commentsFilename === 'function') {
+                commentsFilename = commentsFilename.bind(null, file);
+              }
             }
 
             let query = '';
@@ -330,6 +337,7 @@ class TerserPlugin {
           }
 
           const task = {
+            asset,
             file,
             input,
             inputSourceMap,
@@ -339,21 +347,30 @@ class TerserPlugin {
             minify: this.options.minify,
           };
 
-          if (this.options.cache) {
-            const defaultCacheKeys = {
+          if (TerserPlugin.isWebpack4()) {
+            if (this.options.cache) {
+              const defaultCacheKeys = {
+                terser: terserPackageJson.version,
+                // eslint-disable-next-line global-require
+                'terser-webpack-plugin': require('../package.json').version,
+                'terser-webpack-plugin-options': this.options,
+                nodeVersion: process.version,
+                filename: file,
+                contentHash: crypto
+                  .createHash('md4')
+                  .update(input)
+                  .digest('hex'),
+              };
+
+              task.cacheKeys = this.options.cacheKeys(defaultCacheKeys, file);
+            }
+          } else {
+            task.cacheKeys = {
               terser: terserPackageJson.version,
               // eslint-disable-next-line global-require
               'terser-webpack-plugin': require('../package.json').version,
               'terser-webpack-plugin-options': this.options,
-              nodeVersion: process.version,
-              filename: file,
-              contentHash: crypto
-                .createHash('md4')
-                .update(input)
-                .digest('hex'),
             };
-
-            task.cacheKeys = this.options.cacheKeys(defaultCacheKeys, file);
           }
 
           tasks.push(task);
@@ -373,8 +390,14 @@ class TerserPlugin {
         return Promise.resolve();
       }
 
+      const CacheEngine = TerserPlugin.isWebpack4()
+        ? // eslint-disable-next-line global-require
+          require('./Webpack4Cache').default
+        : // eslint-disable-next-line global-require
+          require('./Webpack5Cache').default;
+
       const taskRunner = new TaskRunner({
-        cache: this.options.cache,
+        cache: new CacheEngine(compilation, this.options),
         parallel: this.options.parallel,
       });
 
@@ -522,7 +545,7 @@ class TerserPlugin {
         });
       }
 
-      if (javascript && javascript.JavascriptModulesPlugin) {
+      if (!TerserPlugin.isWebpack4()) {
         const hooks = javascript.JavascriptModulesPlugin.getCompilationHooks(
           compilation
         );