1 //
2 // detail/win_event.hpp
3 // ~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6 //
7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9 //
10 
11 #ifndef BOOST_ASIO_DETAIL_WIN_EVENT_HPP
12 #define BOOST_ASIO_DETAIL_WIN_EVENT_HPP
13 
14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
15 # pragma once
16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17 
18 #include <boost/asio/detail/config.hpp>
19 
20 #if defined(BOOST_ASIO_WINDOWS)
21 
22 #include <boost/asio/detail/assert.hpp>
23 #include <boost/asio/detail/noncopyable.hpp>
24 #include <boost/asio/detail/socket_types.hpp>
25 
26 #include <boost/asio/detail/push_options.hpp>
27 
28 namespace boost {
29 namespace asio {
30 namespace detail {
31 
32 class win_event
33   : private noncopyable
34 {
35 public:
36   // Constructor.
37   BOOST_ASIO_DECL win_event();
38 
39   // Destructor.
40   BOOST_ASIO_DECL ~win_event();
41 
42   // Signal the event. (Retained for backward compatibility.)
43   template <typename Lock>
signal(Lock & lock)44   void signal(Lock& lock)
45   {
46     this->signal_all(lock);
47   }
48 
49   // Signal all waiters.
50   template <typename Lock>
signal_all(Lock & lock)51   void signal_all(Lock& lock)
52   {
53     BOOST_ASIO_ASSERT(lock.locked());
54     (void)lock;
55     state_ |= 1;
56     ::SetEvent(events_[0]);
57   }
58 
59   // Unlock the mutex and signal one waiter.
60   template <typename Lock>
unlock_and_signal_one(Lock & lock)61   void unlock_and_signal_one(Lock& lock)
62   {
63     BOOST_ASIO_ASSERT(lock.locked());
64     state_ |= 1;
65     bool have_waiters = (state_ > 1);
66     lock.unlock();
67     if (have_waiters)
68       ::SetEvent(events_[1]);
69   }
70 
71   // If there's a waiter, unlock the mutex and signal it.
72   template <typename Lock>
maybe_unlock_and_signal_one(Lock & lock)73   bool maybe_unlock_and_signal_one(Lock& lock)
74   {
75     BOOST_ASIO_ASSERT(lock.locked());
76     state_ |= 1;
77     if (state_ > 1)
78     {
79       lock.unlock();
80       ::SetEvent(events_[1]);
81       return true;
82     }
83     return false;
84   }
85 
86   // Reset the event.
87   template <typename Lock>
clear(Lock & lock)88   void clear(Lock& lock)
89   {
90     BOOST_ASIO_ASSERT(lock.locked());
91     (void)lock;
92     ::ResetEvent(events_[0]);
93     state_ &= ~std::size_t(1);
94   }
95 
96   // Wait for the event to become signalled.
97   template <typename Lock>
wait(Lock & lock)98   void wait(Lock& lock)
99   {
100     BOOST_ASIO_ASSERT(lock.locked());
101     while ((state_ & 1) == 0)
102     {
103       state_ += 2;
104       lock.unlock();
105       ::WaitForMultipleObjects(2, events_, false, INFINITE);
106       lock.lock();
107       state_ -= 2;
108     }
109   }
110 
111 private:
112   HANDLE events_[2];
113   std::size_t state_;
114 };
115 
116 } // namespace detail
117 } // namespace asio
118 } // namespace boost
119 
120 #include <boost/asio/detail/pop_options.hpp>
121 
122 #if defined(BOOST_ASIO_HEADER_ONLY)
123 # include <boost/asio/detail/impl/win_event.ipp>
124 #endif // defined(BOOST_ASIO_HEADER_ONLY)
125 
126 #endif // defined(BOOST_ASIO_WINDOWS)
127 
128 #endif // BOOST_ASIO_DETAIL_WIN_EVENT_HPP
129