feat: Allow to change how cache is stored

README.md

@@ -49,6 +49,8 @@ module.exports = {
 |:--:|:--:|:-----:|:----------|
 |**`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.|
+|**`writer`**|`{Function(cacheFilename, content, callback) -> {void}}`|`undefined`|Allows you to override default write cache data to file (e.g. Redis, memcached).|
+|**`reader`**|`{Function(cacheFilename, callback) -> {void}}`|`undefined`|Allows you to override default read cache data from file.|
 
 <h2 align="center">Examples</h2>
 
@@ -95,6 +97,62 @@ module.exports = {
 }
 ```
 
+### `Write cache data to redis`
+
+**webpack.config.js**
+```js
+const redis = require('redis');
+
+// ...
+// ... connect to client
+// ...
+
+const BUILD_CACHE_TIMEOUT = 24 * 3600; // 1 day
+
+function redisKey(filename) {
+    return `build:cache:${filename}`;
+}
+
+function reader(filename, callback) {
+      client.get(redisKey(filename), (err, result) => {
+          if (err) {
+              return callback(err);
+          }
+
+          if (!result) {
+              return callback(new Error(`Key ${redisKey(filename)} not found`));
+          }
+
+          callback(null, result);
+    });
+}
+
+function writer(filename, content, callback) {
+      client.set(redisKey(filename), content, 'EX', BUILD_CACHE_TIMEOUT, callback);
+}
+
+module.exports = {
+  module: {
+    rules: [
+      {
+        test: /\.js$/,
+        use: [
+          {
+            loader: 'cache-loader',
+            options: {
+              reader,
+              writer
+            }
+          },
+          'babel-loader'
+        ],
+        include: path.resolve('src')
+      }
+    ]
+  }
+}
+```
+
 <h2 align="center">Maintainers</h2>
 
 <table>