Issue 5179 - Implement asynchronous executor with a controllable lifetime

include/AdblockPlus/SynchronizedCollection.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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
@@ skipping 40 matching lines @@
     void push_back(value_type&& value)
     {
       {
         std::lock_guard<std::mutex> lock(mutex);
         collection.push_back(std::move(value));
       }
       conditionVar.notify_one();
     }
 
     /**
-     * Extracts normally a firtst of currently stored elements and returns it.

[hub, 2018/02/23 22:59:35]

I think the comment should read "Extracts the first stored element and returns
it".

[sergei, 2018/03/01 11:18:37]

Yeah, perhaps it's better, done.

+     * Extracts the first stored element and returns it.
      * Pay attention that the call of this method blocks the execution until
      * there is at least one element added to the collection.
      */
     value_type pop_front()
     {
       std::unique_lock<std::mutex> lock(mutex);
       conditionVar.wait(lock, [this]()->bool
       {
         return !collection.empty();
       });
       value_type retValue = collection.front();
       collection.pop_front();
       return retValue;
     }
   protected:
     Container collection;
     std::mutex mutex;
     std::condition_variable conditionVar;
   };
 }