Issue 5183 - Provide async interface for FileSystem

include/AdblockPlus/JsEngine.h

Index: include/AdblockPlus/JsEngine.h
===================================================================
--- a/include/AdblockPlus/JsEngine.h
+++ b/include/AdblockPlus/JsEngine.h
@@ -51,16 +51,21 @@
   typedef std::shared_ptr<JsEngine> JsEnginePtr;
 
   /**
    * A factory to construct DefaultTimer.
    */
   TimerPtr CreateDefaultTimer();
 
   /**
+   * A factory to construct DefaultFileSystem.
+   */
+  FileSystemPtr CreateDefaultFileSystem();
+
+  /**
    * A factory to construct DefaultWebRequest.
    */
   WebRequestPtr CreateDefaultWebRequest();
 
   /**
    * Scope based isolate manager. Creates a new isolate instance on
    * constructing and disposes it on destructing.
    */
@@ -114,23 +119,25 @@
       friend class JsEngine;
       JsWeakValuesLists::const_iterator iterator;
     };
 
     /**
      * Creates a new JavaScript engine instance.
      * @param appInfo Information about the app.
      * @param timer Implementation of timer.
+     * @param fileSystem Implementation of filesystem.
      * @param webRequest Implementation of web request.
      * @param isolate v8::Isolate wrapper. This parameter should be considered
      *        as a temporary hack for tests, it will go away. Issue #3593.
      * @return New `JsEngine` instance.
      */
     static JsEnginePtr New(const AppInfo& appInfo = AppInfo(),
       TimerPtr timer = CreateDefaultTimer(),
+      FileSystemPtr fileSystem = CreateDefaultFileSystem(),
       WebRequestPtr webRequest = CreateDefaultWebRequest());
 
     /**
      * Registers the callback function for an event.
      * @param eventName Event name. Note that this can be any string - it's a
      *        general purpose event handling mechanism.
      * @param callback Event callback function.
      */
@@ -252,27 +259,29 @@
      * Converts v8 arguments to `JsValue` objects.
      * @param arguments `v8::FunctionCallbackInfo` object containing the arguments to
      *        convert.
      * @return List of arguments converted to `const JsValue` objects.
      */
     JsValueList ConvertArguments(const v8::FunctionCallbackInfo<v8::Value>& arguments);
 
     /**
-     * @see `SetFileSystem()`.
+     * Private functionality.
+     * @return The asynchronous IFileSystem implementation.
      */
-    FileSystemPtr GetFileSystem() const;
+    FileSystemPtr GetAsyncFileSystem() const;
 
     /**
-     * Sets the `FileSystem` implementation used for all file I/O.
-     * Setting this is optional, the engine will use a `DefaultFileSystem`
-     * instance by default, which might be sufficient.
+     * Sets the synchronous `FileSystem` implementation used for all
+     * file I/O. Setting this is optional, the engine will use the
+     * implementation created by `CreateDefaultFileSystem()` by
+     * default, which might be sufficient.
      * @param The `FileSystem` instance to use.
      */
-    void SetFileSystem(const FileSystemPtr& val);
+    void SetFileSystem(const FileSystemSyncPtr& val);
 
     /**
      * Sets the `WebRequest` implementation used for XMLHttpRequests.
      * Setting this is optional, the engine will use a `DefaultWebRequest`
      * instance by default, which might be sufficient.
      * @param The `WebRequest` instance to use.
      */
     void SetWebRequest(const WebRequestSharedPtr& val);
@@ -309,25 +318,26 @@
     /**
      * Notifies JS engine about critically low memory what should cause a
      * garbage collection.
      */
     void NotifyLowMemory();
   private:
     void CallTimerTask(const JsWeakValuesID& timerParamsID);
 
-    explicit JsEngine(TimerPtr timer, WebRequestPtr webRequest);
+    explicit JsEngine(TimerPtr timer, FileSystemPtr fileSystem, WebRequestPtr webRequest);
 
     JsValue GetGlobalObject();
 
     /// Isolate must be disposed only after disposing of all objects which are
     /// using it.
     ScopedV8Isolate isolate;
 
     FileSystemPtr fileSystem;
+    FileSystemSyncPtr fileSystemLegacy;
     LogSystemPtr logSystem;
     std::unique_ptr<v8::Global<v8::Context>> context;
     EventMap eventCallbacks;
     std::mutex eventCallbacksMutex;
     JsWeakValuesLists jsWeakValuesLists;
     std::mutex jsWeakValuesListsMutex;
     TimerPtr timer;
     WebRequestPtr webRequest;