text: //===----------------------------------------------------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is dual licensed under the MIT and the University of Illinois Open
  // Source Licenses. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  
  // Copyright (C) 2012 Vicente J. Botet Escriba
  //
  //  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)
  
  // <boost/thread/shared_mutex.hpp>
  
  // class shared_mutex;
  
  // template <class Rep, class Period>
  //     bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
  
  #include <boost/thread/shared_mutex.hpp>
  #include <boost/thread/thread.hpp>
  #include <boost/detail/lightweight_test.hpp>
  
  boost::shared_mutex m;
  
  typedef boost::chrono::steady_clock Clock;
  typedef Clock::time_point time_point;
  typedef Clock::duration duration;
  typedef boost::chrono::milliseconds ms;
  typedef boost::chrono::nanoseconds ns;
  
  void f1()
  {
    time_point t0 = Clock::now();
    // This test is spurious as it depends on the time the thread system switches the threads
    BOOST_TEST(m.try_lock_for(ms(300)+ms(1000)) == true);
    time_point t1 = Clock::now();
    m.unlock();
    ns d = t1 - t0 - ms(250);
    BOOST_TEST(d < ns(5000000)+ms(1000)); // within 5ms
  }
  
  void f2()
  {
    time_point t0 = Clock::now();
    BOOST_TEST(m.try_lock_for(ms(250)) == false);
    time_point t1 = Clock::now();
    ns d = t1 - t0 - ms(250);
    // This test is spurious as it depends on the time the thread system switches the threads
    BOOST_TEST(d < ns(5000000)+ms(1000)); // within 5ms
  }
  
  int main()
  {
    {
      m.lock();
      boost::thread t(f1);
      boost::this_thread::sleep_for(ms(250));
      m.unlock();
      t.join();
    }
    {
      m.lock();
      boost::thread t(f2);
      // This test is spurious as it depends on the time the thread system switches the threads
      boost::this_thread::sleep_for(ms(300)+ms(1000));
      m.unlock();
      t.join();
    }
  
    return boost::report_errors();
  }
  
  