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