1 // Copyright (C) 2002-2003

     2 // David Moore, William E. Kempf

     3 // Copyright (C) 2007-8 Anthony Williams

     4 //

     5 //  Distributed under the Boost Software License, Version 1.0. (See accompanying 

     6 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

     7 

     8 #ifndef BOOST_BARRIER_JDM030602_HPP

     9 #define BOOST_BARRIER_JDM030602_HPP

    10 

    11 #include <boost/thread/detail/config.hpp>

    12 

    13 #include <boost/thread/mutex.hpp>

    14 #include <boost/thread/condition_variable.hpp>

    15 #include <string>

    16 #include <stdexcept>

    17 

    18 #include <boost/config/abi_prefix.hpp>

    19 

    20 namespace boost

    21 {

    22 

    23     class barrier

    24     {

    25     public:

    26         barrier(unsigned int count)

    27             : m_threshold(count), m_count(count), m_generation(0)

    28         {

    29             if (count == 0)

    30                 throw std::invalid_argument("count cannot be zero.");

    31         }

    32     

    33         bool wait()

    34         {

    35             boost::mutex::scoped_lock lock(m_mutex);

    36             unsigned int gen = m_generation;

    37         

    38             if (--m_count == 0)

    39             {

    40                 m_generation++;

    41                 m_count = m_threshold;

    42                 m_cond.notify_all();

    43                 return true;

    44             }

    45 

    46             while (gen == m_generation)

    47                 m_cond.wait(lock);

    48             return false;

    49         }

    50 

    51     private:

    52         mutex m_mutex;

    53         condition_variable m_cond;

    54         unsigned int m_threshold;

    55         unsigned int m_count;

    56         unsigned int m_generation;

    57     };

    58 

    59 }   // namespace boost

    60 

    61 #include <boost/config/abi_suffix.hpp>

    62 

    63 #endif