boost/thread/barrier.hpp

   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