text: 
  //          Copyright Oliver Kowalke 2013.
  // Distributed under the Boost Software License, Version 1.0.
  //    (See accompanying file LICENSE_1_0.txt or copy at
  //          http://www.boost.org/LICENSE_1_0.txt)
  //
  //  based on boost::interprocess::sync::interprocess_spinlock
  
  #ifndef BOOST_FIBERS_RECURSIVE_MUTEX_H
  #define BOOST_FIBERS_RECURSIVE_MUTEX_H
  
  #include <cstddef>
  
  #include <boost/config.hpp>
  
  #include <boost/assert.hpp>
  
  #include <boost/fiber/context.hpp>
  #include <boost/fiber/detail/config.hpp>
  #include <boost/fiber/detail/spinlock.hpp>
  
  #ifdef BOOST_HAS_ABI_HEADERS
  #  include BOOST_ABI_PREFIX
  #endif
  
  #ifdef _MSC_VER
  # pragma warning(push)
  # pragma warning(disable:4251)
  #endif
  
  namespace boost {
  namespace fibers {
  
  class condition_variable;
  
  class BOOST_FIBERS_DECL recursive_mutex {
  private:
      friend class condition_variable;
  
      using wait_queue_type = context::wait_queue_t;
  
      detail::spinlock            wait_queue_splk_{};
      wait_queue_type             wait_queue_{};
      context                 *   owner_{ nullptr };
      std::size_t                 count_{ 0 };
  
  public:
      recursive_mutex() = default;
  
      ~recursive_mutex() {
          BOOST_ASSERT( nullptr == owner_);
          BOOST_ASSERT( 0 == count_);
          BOOST_ASSERT( wait_queue_.empty() );
      }
  
      recursive_mutex( recursive_mutex const&) = delete;
      recursive_mutex & operator=( recursive_mutex const&) = delete;
  
      void lock();
  
      bool try_lock() noexcept;
  
      void unlock();
  };
  
  }}
  
  #ifdef _MSC_VER
  # pragma warning(pop)
  #endif
  
  #ifdef BOOST_HAS_ABI_HEADERS
  #  include BOOST_ABI_SUFFIX
  #endif
  
  #endif // BOOST_FIBERS_RECURSIVE_MUTEX_H
  