1 //
2 // detail/null_event.hpp
3 // ~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2021 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_NULL_EVENT_HPP
12 #define BOOST_ASIO_DETAIL_NULL_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 #include <boost/asio/detail/noncopyable.hpp>
20 
21 #include <boost/asio/detail/push_options.hpp>
22 
23 namespace boost {
24 namespace asio {
25 namespace detail {
26 
27 class null_event
28   : private noncopyable
29 {
30 public:
31   // Constructor.
null_event()32   null_event()
33   {
34   }
35 
36   // Destructor.
~null_event()37   ~null_event()
38   {
39   }
40 
41   // Signal the event. (Retained for backward compatibility.)
42   template <typename Lock>
signal(Lock &)43   void signal(Lock&)
44   {
45   }
46 
47   // Signal all waiters.
48   template <typename Lock>
signal_all(Lock &)49   void signal_all(Lock&)
50   {
51   }
52 
53   // Unlock the mutex and signal one waiter.
54   template <typename Lock>
unlock_and_signal_one(Lock &)55   void unlock_and_signal_one(Lock&)
56   {
57   }
58 
59   // Unlock the mutex and signal one waiter who may destroy us.
60   template <typename Lock>
unlock_and_signal_one_for_destruction(Lock &)61   void unlock_and_signal_one_for_destruction(Lock&)
62   {
63   }
64 
65   // If there's a waiter, unlock the mutex and signal it.
66   template <typename Lock>
maybe_unlock_and_signal_one(Lock &)67   bool maybe_unlock_and_signal_one(Lock&)
68   {
69     return false;
70   }
71 
72   // Reset the event.
73   template <typename Lock>
clear(Lock &)74   void clear(Lock&)
75   {
76   }
77 
78   // Wait for the event to become signalled.
79   template <typename Lock>
wait(Lock &)80   void wait(Lock&)
81   {
82     do_wait();
83   }
84 
85   // Timed wait for the event to become signalled.
86   template <typename Lock>
wait_for_usec(Lock &,long usec)87   bool wait_for_usec(Lock&, long usec)
88   {
89     do_wait_for_usec(usec);
90     return true;
91   }
92 
93 private:
94   BOOST_ASIO_DECL static void do_wait();
95   BOOST_ASIO_DECL static void do_wait_for_usec(long usec);
96 };
97 
98 } // namespace detail
99 } // namespace asio
100 } // namespace boost
101 
102 #include <boost/asio/detail/pop_options.hpp>
103 
104 #if defined(BOOST_ASIO_HEADER_ONLY)
105 # include <boost/asio/detail/impl/null_event.ipp>
106 #endif // defined(BOOST_ASIO_HEADER_ONLY)
107 
108 #endif // BOOST_ASIO_DETAIL_NULL_EVENT_HPP
109