Noissue - generalize storing of `JsValue`s in `JsEngine`

include/AdblockPlus/JsEngine.h

Index: include/AdblockPlus/JsEngine.h
diff --git a/include/AdblockPlus/JsEngine.h b/include/AdblockPlus/JsEngine.h
index 10e27ed4a2b94a0a4e03f6487642c716c6b0b887..55f7e04576fff13af1011158d508bc6cac3d91f4 100644
--- a/include/AdblockPlus/JsEngine.h
+++ b/include/AdblockPlus/JsEngine.h
@@ -89,6 +89,12 @@ namespace AdblockPlus
     friend class JsValue;
     friend class JsContext;
 
+    struct JsWeakValuesList
+    {
+      ~JsWeakValuesList();
+      std::vector<std::unique_ptr<v8::Persistent<v8::Value>>> values;
+    };
+    typedef std::list<JsWeakValuesList> JsWeakValuesLists;
   public:
     /**
      * Event callback function.
@@ -107,6 +113,16 @@ namespace AdblockPlus
     typedef std::map<std::string, EventCallback> EventMap;
 
     /**
+     * An opaque structure representing ID of stored JsValueList.
+     * 
+     */
+    class JsWeakValuesID
+    {
+      friend class JsEngine;
+      JsWeakValuesLists::const_iterator iterator;
+    };
+
+    /**
      * Creates a new JavaScript engine instance.
      * @param appInfo Information about the app.
      * @param timer Implementation of timer.
@@ -204,6 +220,26 @@ namespace AdblockPlus
      */
     static JsEnginePtr FromArguments(const v8::Arguments& arguments);
 
+    /**
+     * Stores `JsValue`s in a way they don't keep a strong reference to
+     * `JsEngine` and which are destroyed when `JsEngine` is destroyed. These
+     * methods should be used when one needs to carry a JsValue in a callback
+     * directly or indirectly passed to `JsEngine`.
+     * The method is thread-safe.
+     * @param `JsValueList` to store.
+     * @return `JsWeakValuesID` of stored values which allows to restore them
+     * later.
+     */
+    JsWeakValuesID StoreJsValues(const JsValueList& values);
+
+    /**
+     * Extracts and removes from `JsEngine` earlier stored `JsValue`s.
+     * The method is thread-safe.
+     * @param id `JsWeakValuesID` of values.
+     * @return `JsValueList` of stored values.
+     */
+    JsValueList TakeJsValues(const JsWeakValuesID& id);
+
     /*
      * Private functionality required to implement timers.
      * @param arguments `v8::Arguments` is the arguments received in C++
@@ -288,13 +324,7 @@ namespace AdblockPlus
     }
 
   private:
-    struct TimerTask
-    {
-      ~TimerTask();
-      std::vector<std::unique_ptr<v8::Persistent<v8::Value>>> arguments;
-    };
-    typedef std::list<TimerTask> TimerTasks;
-    void CallTimerTask(const TimerTasks::const_iterator& timerTaskIterator);
+    void CallTimerTask(const JsWeakValuesID& timerParamsID);
 
     explicit JsEngine(const ScopedV8IsolatePtr& isolate, TimerPtr timer);
 
@@ -312,7 +342,8 @@ namespace AdblockPlus
     std::mutex eventCallbacksMutex;
     mutable std::mutex isConnectionAllowedMutex;
     IsConnectionAllowedCallback isConnectionAllowed;
-    TimerTasks timerTasks;
+    JsWeakValuesLists jsWeakValuesLists;
+    std::mutex jsWeakValuesListsMutex;
     TimerPtr timer;
   };
 }