threading.icc

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
// $Id$
/**
 * @file AthContainers/tools.threading.icc
 * @author scott snyder <snyder@bnl.gov>
 * @date Sep, 2013
 * @brief Threading definitions.
 */
 
 
namespace AthContainers_detail {
 
 
#ifndef ATHCONTAINERS_NO_THREADS
 
 
/**
 * @brief An acquire/release fence.
 */
inline
void fence_acq_rel()
{
  std::atomic_thread_fence (std::memory_order_acq_rel);
}
 
 
/**
 * @brief A sequentially-consistent fence.
 */
inline
void fence_seq_cst()
{
  std::atomic_thread_fence (std::memory_order_seq_cst);
}
 
 
#endif
 
 
/**
 * @brief Take out a shared lock on @c obj and remember it.
 * @param obj The lockable object.
 */
template <typename LOCKABLE>
inline
strict_shared_lock<LOCKABLE>::strict_shared_lock (lockable_type& obj)
  : m_obj(obj)
{
  obj.lock_shared(); // locks on construction
}
 
 
/**
 * @brief Take out a shared lock on @c obj and remember it.
 * @param obj The lockable object.
 */
template <typename LOCKABLE>
inline
strict_shared_lock<LOCKABLE>::strict_shared_lock (const lockable_type& obj)
  : m_obj(const_cast<lockable_type&>(obj))
{
  obj.lock_shared(); // locks on construction
}
 
 
/**
 * @brief Release the held lock.
 */
template <typename LOCKABLE>
inline
strict_shared_lock<LOCKABLE>::~strict_shared_lock()
{
  m_obj.unlock_shared();  //  unlocks on destruction 
}
  
 
/**
 * @brief Take out an upgrade lock on @c obj and remember it.
 * @param obj The lockable object.
 */
template <typename LOCKABLE>
inline
upgrading_lock<LOCKABLE>::upgrading_lock (lockable_type& obj)
  : m_obj (obj)
{
  m_obj.lock_upgrade();
  m_exclusive = false;
}
 
 
/**
 * @brief Release the held lock.
 */
template <typename LOCKABLE>
inline
upgrading_lock<LOCKABLE>::~upgrading_lock()
{
  if (m_exclusive)
    m_obj.unlock();
  else
    m_obj.unlock_upgrade();
}
 
 
/**
 * @brief Convert the lock from upgrade to exclusive.
 */
template <typename LOCKABLE>
inline
void upgrading_lock<LOCKABLE>::upgrade()
{
  if (!m_exclusive) {
    m_obj.unlock_upgrade_and_lock();
    m_exclusive = true;
  }
}
 
 
 
} // namespace AthContainers_detail