ceph/src/boost/boost/fiber/detail/thread_barrier.hpp

   1
   2 //          Copyright Oliver Kowalke 2013.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 //    (See accompanying file LICENSE_1_0.txt or copy at
   5 //          http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_FIBER_DETAIL_THREAD_BARRIER_H
   8 #define BOOST_FIBER_DETAIL_THREAD_BARRIER_H
   9
  10 #include <cstddef>
  11 #include <condition_variable>
  12 #include <mutex>
  13
  14 #include <boost/assert.hpp>
  15 #include <boost/config.hpp>
  16
  17 #include <boost/fiber/detail/config.hpp>
  18
  19 #ifdef BOOST_HAS_ABI_HEADERS
  20 # include BOOST_ABI_PREFIX
  21 #endif
  22
  23 namespace boost {
  24 namespace fibers {
  25 namespace detail {
  26
  27 class thread_barrier {
  28 private:
  29         std::size_t             initial_;
  30         std::size_t             current_;
  31         bool                    cycle_{ true };
  32     std::mutex              mtx_{};
  33     std::condition_variable cond_{};
  34
  35 public:
  36         explicit thread_barrier( std::size_t initial) :
  37         initial_{ initial },
  38         current_{ initial_ } {
  39         BOOST_ASSERT ( 0 != initial);
  40     }
  41
  42     thread_barrier( thread_barrier const&) = delete;
  43     thread_barrier & operator=( thread_barrier const&) = delete;
  44
  45     bool wait() {
  46         std::unique_lock< std::mutex > lk( mtx_);
  47         const bool cycle = cycle_;
  48         if ( 0 == --current_) {
  49             cycle_ = ! cycle_;
  50             current_ = initial_;
  51             lk.unlock(); // no pessimization
  52             cond_.notify_all();
  53             return true;
  54         } else {
  55             cond_.wait( lk, [&](){ return cycle != cycle_; });
  56         }
  57         return false;
  58     }
  59 };
  60
  61 }}}
  62
  63 #endif // BOOST_FIBER_DETAIL_THREAD_BARRIER_H