Issue 5118 - Lock the platform interfaces before use

include/AdblockPlus/Platform.h

Index: include/AdblockPlus/Platform.h
===================================================================
--- a/include/AdblockPlus/Platform.h
+++ b/include/AdblockPlus/Platform.h
@@ -102,43 +102,36 @@
     /**
      * Synchronous equivalent of `CreateFilterEngineAsync`.
      * Internally it blocks and waits for finishing of certain asynchronous
      * operations, please ensure that provided implementation does not lead to
      * a dead lock.
      */
     FilterEngine& GetFilterEngine();
 
-    /**
-    * @return The asynchronous ITimer implementation.
-     */
-    ITimer& GetTimer();
+    typedef std::function<void(ITimer&)> WithTimerCallback;
+    void WithTimer(const WithTimerCallback&);
 
-    /**
-     * @return The asynchronous IFileSystem implementation.
-     */
-    IFileSystem& GetFileSystem();
+    typedef std::function<void(IFileSystem&)> WithFileSystemCallback;
+    void WithFileSystem(const WithFileSystemCallback&);
 
-    /**
-    * @return The asynchronous IWebRequest implementation.
-    */
-    IWebRequest& GetWebRequest();
+    typedef std::function<void(IWebRequest&)> WithWebRequestCallback;
+    void WithWebRequest(const WithWebRequestCallback&);
 
-    /**
-     * @return The LogSystem implementation.
-     */
-    LogSystem& GetLogSystem();
+    typedef std::function<void(LogSystem&)> WithLogSystemCallback;
+    void WithLogSystem(const WithLogSystemCallback&);
 
   private:
     LogSystemPtr logSystem;
     TimerPtr timer;
     FileSystemPtr fileSystem;
     WebRequestPtr webRequest;
     // used for creation and deletion of modules.
     std::mutex modulesMutex;
+    std::recursive_mutex interfacesMutex;

[sergei, 2017/09/13 19:20:53]

What do you think about making the methods WithSomeInterface virtual, moving the
mutex into DefaultPlatform and overriding the corresponding methods there which
are using the mutex? I think about it because we basically "should pay only for
what we use", if the implementation of the interfaces does not imply
multi-threading then then this mutex is not required. Though, it seems a small
optimization and there is still `modulesMutex`, which should not be touched in
this codereview.

[hub, 2017/09/13 19:50:49]

I can do that.

     std::shared_ptr<JsEngine> jsEngine;
     std::shared_future<FilterEnginePtr> filterEngine;
   };
 
   /**
    * A helper class allowing to construct a default Platform and to obtain
    * the Scheduler used by Platform before the latter is constructed.
    */