Chris@16: //
Chris@16: // detail/std_event.hpp
Chris@16: // ~~~~~~~~~~~~~~~~~~~~
Chris@16: //
Chris@101: // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: 
Chris@16: #ifndef BOOST_ASIO_DETAIL_STD_EVENT_HPP
Chris@16: #define BOOST_ASIO_DETAIL_STD_EVENT_HPP
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: # pragma once
Chris@16: #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: 
Chris@16: #include <boost/asio/detail/config.hpp>
Chris@16: 
Chris@16: #if defined(BOOST_ASIO_HAS_STD_MUTEX_AND_CONDVAR)
Chris@16: 
Chris@16: #include <chrono>
Chris@16: #include <condition_variable>
Chris@16: #include <boost/asio/detail/assert.hpp>
Chris@16: #include <boost/asio/detail/noncopyable.hpp>
Chris@16: 
Chris@16: #include <boost/asio/detail/push_options.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace asio {
Chris@16: namespace detail {
Chris@16: 
Chris@16: class std_event
Chris@16:   : private noncopyable
Chris@16: {
Chris@16: public:
Chris@16:   // Constructor.
Chris@16:   std_event()
Chris@101:     : state_(0)
Chris@16:   {
Chris@16:   }
Chris@16: 
Chris@16:   // Destructor.
Chris@16:   ~std_event()
Chris@16:   {
Chris@16:   }
Chris@16: 
Chris@101:   // Signal the event. (Retained for backward compatibility.)
Chris@16:   template <typename Lock>
Chris@16:   void signal(Lock& lock)
Chris@16:   {
Chris@101:     this->signal_all(lock);
Chris@101:   }
Chris@101: 
Chris@101:   // Signal all waiters.
Chris@101:   template <typename Lock>
Chris@101:   void signal_all(Lock& lock)
Chris@101:   {
Chris@16:     BOOST_ASIO_ASSERT(lock.locked());
Chris@16:     (void)lock;
Chris@101:     state_ |= 1;
Chris@101:     cond_.notify_all();
Chris@16:   }
Chris@16: 
Chris@101:   // Unlock the mutex and signal one waiter.
Chris@16:   template <typename Lock>
Chris@101:   void unlock_and_signal_one(Lock& lock)
Chris@16:   {
Chris@16:     BOOST_ASIO_ASSERT(lock.locked());
Chris@101:     state_ |= 1;
Chris@101:     bool have_waiters = (state_ > 1);
Chris@16:     lock.unlock();
Chris@101:     if (have_waiters)
Chris@101:       cond_.notify_one();
Chris@101:   }
Chris@101: 
Chris@101:   // If there's a waiter, unlock the mutex and signal it.
Chris@101:   template <typename Lock>
Chris@101:   bool maybe_unlock_and_signal_one(Lock& lock)
Chris@101:   {
Chris@101:     BOOST_ASIO_ASSERT(lock.locked());
Chris@101:     state_ |= 1;
Chris@101:     if (state_ > 1)
Chris@101:     {
Chris@101:       lock.unlock();
Chris@101:       cond_.notify_one();
Chris@101:       return true;
Chris@101:     }
Chris@101:     return false;
Chris@16:   }
Chris@16: 
Chris@16:   // Reset the event.
Chris@16:   template <typename Lock>
Chris@16:   void clear(Lock& lock)
Chris@16:   {
Chris@16:     BOOST_ASIO_ASSERT(lock.locked());
Chris@16:     (void)lock;
Chris@101:     state_ &= ~std::size_t(1);
Chris@16:   }
Chris@16: 
Chris@16:   // Wait for the event to become signalled.
Chris@16:   template <typename Lock>
Chris@16:   void wait(Lock& lock)
Chris@16:   {
Chris@16:     BOOST_ASIO_ASSERT(lock.locked());
Chris@16:     unique_lock_adapter u_lock(lock);
Chris@101:     while ((state_ & 1) == 0)
Chris@101:     {
Chris@101:       waiter w(state_);
Chris@16:       cond_.wait(u_lock.unique_lock_);
Chris@101:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Timed wait for the event to become signalled.
Chris@16:   template <typename Lock>
Chris@16:   bool wait_for_usec(Lock& lock, long usec)
Chris@16:   {
Chris@16:     BOOST_ASIO_ASSERT(lock.locked());
Chris@16:     unique_lock_adapter u_lock(lock);
Chris@101:     if ((state_ & 1) == 0)
Chris@101:     {
Chris@101:       waiter w(state_);
Chris@16:       cond_.wait_for(u_lock.unique_lock_, std::chrono::microseconds(usec));
Chris@101:     }
Chris@101:     return (state_ & 1) != 0;
Chris@16:   }
Chris@16: 
Chris@16: private:
Chris@16:   // Helper class to temporarily adapt a scoped_lock into a unique_lock so that
Chris@16:   // it can be passed to std::condition_variable::wait().
Chris@16:   struct unique_lock_adapter
Chris@16:   {
Chris@16:     template <typename Lock>
Chris@16:     explicit unique_lock_adapter(Lock& lock)
Chris@16:       : unique_lock_(lock.mutex().mutex_, std::adopt_lock)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     ~unique_lock_adapter()
Chris@16:     {
Chris@16:       unique_lock_.release();
Chris@16:     }
Chris@16: 
Chris@16:     std::unique_lock<std::mutex> unique_lock_;
Chris@16:   };
Chris@16: 
Chris@101:   // Helper to increment and decrement the state to track outstanding waiters.
Chris@101:   class waiter
Chris@101:   {
Chris@101:   public:
Chris@101:     explicit waiter(std::size_t& state)
Chris@101:       : state_(state)
Chris@101:     {
Chris@101:       state_ += 2;
Chris@101:     }
Chris@101: 
Chris@101:     ~waiter()
Chris@101:     {
Chris@101:       state_ -= 2;
Chris@101:     }
Chris@101: 
Chris@101:   private:
Chris@101:     std::size_t& state_;
Chris@101:   };
Chris@101: 
Chris@16:   std::condition_variable cond_;
Chris@101:   std::size_t state_;
Chris@16: };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: } // namespace asio
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/asio/detail/pop_options.hpp>
Chris@16: 
Chris@16: #endif // defined(BOOST_ASIO_HAS_STD_MUTEX_AND_CONDVAR)
Chris@16: 
Chris@16: #endif // BOOST_ASIO_DETAIL_STD_EVENT_HPP