//          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)

#include "boost/fiber/barrier.hpp"

#include <mutex>
#include <system_error>

#include "boost/fiber/exceptions.hpp"

#ifdef BOOST_HAS_ABI_HEADERS
#  include BOOST_ABI_PREFIX
#endif

namespace boost {
namespace fibers {

barrier::barrier( std::size_t initial) :
    initial_{ initial },
    current_{ initial_ } {
    if ( BOOST_UNLIKELY( 0 == initial) ) {
        throw fiber_error{ std::make_error_code( std::errc::invalid_argument),
                           "boost fiber: zero initial barrier count" };
    }
}

bool
barrier::wait() {
    std::unique_lock< mutex > lk{ mtx_ };
    const std::size_t cycle = cycle_;
    if ( 0 == --current_) {
        ++cycle_;
        current_ = initial_;
        lk.unlock(); // no pessimization
        cond_.notify_all();
        return true;
    }

    cond_.wait( lk, [&]{ return cycle != cycle_; });
    return false;
}

}}

#ifdef BOOST_HAS_ABI_HEADERS
#  include BOOST_ABI_SUFFIX
#endif