feat: add overrideDependencies option (options.overrideDependencies)

.babelrc

@@ -1,18 +1,5 @@
 {
   "presets": [
-    [
-      "env",
-      {
-        "useBuiltIns": true,
-        "targets": {
-          "node": 4.3
-        },
-        "exclude": [
-          "transform-async-to-generator",
-          "transform-regenerator"
-        ]
-      }
-    ],
     [
       "env",
       {
@@ -45,4 +32,4 @@
       ]
     }
   }
-}
+}

README.md

@@ -43,12 +43,15 @@ module.exports = {
 
 > ⚠️ Note that there is an overhead for saving the reading and saving the cache file, so only use this loader to cache expensive loaders.
 
+The loader checks timestamp values of all dependencies of the cached modules. Only if modification timestamp hasn't changed the cached result is used.
+
 <h2 align="center">Options</h2>
 
 |Name|Type|Default|Description|
 |:--:|:--:|:-----:|:----------|
 |**`cacheDirectory`**|`{String}`|`path.resolve('.cache-loader')`|Provide a cache directory where cache items should be stored|
 |**`cacheIdentifier`**|`{String}`|`cache-loader:{version} {process.env.NODE_ENV}`|Provide an invalidation identifier which is used to generate the hashes. You can use it for extra dependencies of loaders.|
+|**`overrideDependencies`**|`{Array<String>}`|none|Provide different dependencies for the modules. This override the default dependencies.|
 
 <h2 align="center">Examples</h2>
 
@@ -95,6 +98,33 @@ module.exports = {
 }
 ```
 
+<h2 align="center">Hints</h2>
+
+For extra performance you could override the dependencies of modules for rarly changing modules:
+
+```js
+module.exports = {
+  module: {
+    rules: [
+      {
+        test: /\.js$/,
+        use: [
+          {
+            loader: 'cache-loader',
+            options: {
+              overrideDependencies: [path.resolve('yarn.lock')]
+            }
+          }
+        ],
+        include: path.resolve('node_modules')
+      }
+    ]
+  }
+}
+```
+
+With this config timestamps from files are no longer checked. Instead only the timestamp of the yarn lockfile is checked, which should be ok for normal yarn usage.
+
 <h2 align="center">Maintainers</h2>
 
 <table>

example/.babelrc

@@ -5,7 +5,7 @@
       {
         "useBuiltIns": true,
         "targets": {
-          "node": 4.3
+          "node": "4.3"
         },
         "exclude": [
           "transform-async-to-generator",
@@ -32,4 +32,4 @@
       ]
     }
   }
-}
+}

src/index.js

@@ -12,8 +12,9 @@ const ENV = process.env.NODE_ENV || 'development';
 function loader(...args) {
   const callback = this.async();
   const { data } = this;
-  const dependencies = this.getDependencies().concat(this.loaders.map(l => l.path));
-  const contextDependencies = this.getContextDependencies();
+  const { fileExists, cacheFile, remainingRequest, cacheIdentifier, overrideDependencies } = data;
+  const dependencies = overrideDependencies || this.getDependencies().concat(this.loaders.map(l => l.path));
+  const contextDependencies = overrideDependencies ? [] : this.getContextDependencies();
   const toDepDetails = (dep, mapCallback) => {
     fs.stat(dep, (err, stats) => {
       if (err) {
@@ -36,9 +37,9 @@ function loader(...args) {
     }
     const [deps, contextDeps] = taskResults;
     const writeCacheFile = () => {
-      fs.writeFile(data.cacheFile, JSON.stringify({
-        remainingRequest: data.remainingRequest,
-        cacheIdentifier: data.cacheIdentifier,
+      fs.writeFile(cacheFile, JSON.stringify({
+        remainingRequest,
+        cacheIdentifier,
         dependencies: deps,
         contextDependencies: contextDeps,
         result: args,
@@ -47,11 +48,11 @@ function loader(...args) {
         callback(null, ...args);
       });
     };
-    if (data.fileExists) {
+    if (fileExists) {
       // for performance skip creating directory
       writeCacheFile();
     } else {
-      mkdirp(path.dirname(data.cacheFile), (mkdirErr) => {
+      mkdirp(path.dirname(cacheFile), (mkdirErr) => {
         if (mkdirErr) {
           callback(null, ...args);
           return;
@@ -69,14 +70,15 @@ function pitch(remainingRequest, prevRequest, dataInput) {
     cacheIdentifier: `cache-loader:${pkgVersion} ${ENV}`,
   };
   const options = Object.assign({}, defaultOptions, loaderOptions);
-  const { cacheIdentifier, cacheDirectory } = options;
+  const { cacheIdentifier, cacheDirectory, overrideDependencies } = options;
   const data = dataInput;
   const callback = this.async();
   const hash = digest(`${cacheIdentifier}\n${remainingRequest}`);
   const cacheFile = path.join(cacheDirectory, `${hash}.json`);
   data.remainingRequest = remainingRequest;
   data.cacheIdentifier = cacheIdentifier;
   data.cacheFile = cacheFile;
+  data.overrideDependencies = overrideDependencies;
   fs.readFile(cacheFile, 'utf-8', (readFileErr, content) => {
     if (readFileErr) {
       callback();
@@ -95,7 +97,8 @@ function pitch(remainingRequest, prevRequest, dataInput) {
       callback();
       return;
     }
-    async.each(cacheData.dependencies.concat(cacheData.contextDependencies), (dep, eachCallback) => {
+    const dependencies = cacheData.dependencies.concat(cacheData.contextDependencies);
+    async.each(dependencies, (dep, eachCallback) => {
       fs.stat(dep.path, (statErr, stats) => {
         if (statErr) {
           eachCallback(statErr);