Issue 3594 - remove circular references JsEngine-JsValue-JsEngine

test/FilterEngine.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include "BaseJsTest.h"
+#include <thread>
+#include <chrono>
 
 namespace
 {
   typedef std::shared_ptr<AdblockPlus::FilterEngine> FilterEnginePtr;
 
   class VeryLazyFileSystem : public LazyFileSystem
   {
   public:
     StatResult Stat(const std::string& path) const
     {
@@ skipping 502 matching lines @@
 
   ASSERT_FALSE(filterEngine->IsElemhideWhitelisted(
       "http://example.co.uk",
       documentUrls1));
 }
 
 TEST(NewFilterEngineTest, MemoryLeak_NoCircularReferences)
 {
   std::weak_ptr<AdblockPlus::JsEngine> weakJsEngine;
   {
     auto jsEngine = AdblockPlus::JsEngine::New();

[Oleksandr, 2016/11/25 10:38:04]

Did you want to assign weakJsEngine to jsEngine inside this block for testing
purposes? Otherwise I don't see what this test actually tests for.

[sergei, 2016/11/25 12:04:46]

Of course, cannot believe I have missed it))

+    weakJsEngine = jsEngine;
     jsEngine->SetFileSystem(AdblockPlus::FileSystemPtr(new LazyFileSystem()));
     jsEngine->SetWebRequest(AdblockPlus::WebRequestPtr(new LazyWebRequest()));
     jsEngine->SetLogSystem(AdblockPlus::LogSystemPtr(new LazyLogSystem()));
     auto filterEngine = FilterEnginePtr(new AdblockPlus::FilterEngine(jsEngine));
   }
+  {
+    // It's a hack to figure current race condition out (better than nothing):
+    // IO or timer thread still can aquire a strong reference to JsEngine right
+    // before destroying filterEngine holding JsEngine and keep it for some
+    // time, so here we need to give it a reasonable amount of time to finish
+    // the current operation.
+    uint16_t attempts = 10;
+    while (attempts-- > 0 && weakJsEngine.lock())
+      std::this_thread::sleep_for(std::chrono::milliseconds(500));
+  }
   EXPECT_FALSE(weakJsEngine.lock());
 }