ThreadLocalHolder.h

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef G4ATLASTOOLS_THREADLOCALHOLDER_H
#define G4ATLASTOOLS_THREADLOCALHOLDER_H

 
 
// System includes
#include <thread>
#include <utility>
 
// Other includes
#include "tbb/concurrent_unordered_map.h"
 
 
namespace thread_utils
{

  template<class T>
  class ThreadLocalHolder
  {
 
    public:
 
      using MapKey_t = std::thread::id;
      using MapVal_t = T*;
      using MapHash_t = std::hash<MapKey_t>;
      using ThreadMap_t =
        tbb::concurrent_unordered_map< MapKey_t, MapVal_t, MapHash_t >;

      T* get() {
        auto itr = m_threadMap.find( std::this_thread::get_id() );
        if(itr == m_threadMap.end()) return nullptr;
        return itr->second;
      }

      void set(T* obj) {
        const auto tid = std::this_thread::get_id();
        m_threadMap.insert( std::make_pair(tid, obj) );
      }

      const ThreadMap_t& getMap() const {
        return m_threadMap;
      }
 
    protected:

      ThreadMap_t m_threadMap;
 
  }; // class ThreadLocalHolder
 

  template<class T>
  class ThreadLocalOwner : public ThreadLocalHolder<T>
  {
    public:
      ~ThreadLocalOwner() {
        for(auto& mapPair : this->m_threadMap)
          delete mapPair.second;
      }
  }; // class ThreadLocalOwner
 
} // namespace thread_utils
 
#endif