1 //
2 // detail/posix_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_POSIX_EVENT_HPP
12 #define BOOST_ASIO_DETAIL_POSIX_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_HAS_PTHREADS)
21 
22 #include <pthread.h>
23 #include <boost/asio/detail/assert.hpp>
24 #include <boost/asio/detail/noncopyable.hpp>
25 
26 #include <boost/asio/detail/push_options.hpp>
27 
28 namespace boost {
29 namespace asio {
30 namespace detail {
31 
32 class posix_event
33   : private noncopyable
34 {
35 public:
36   // Constructor.
37   BOOST_ASIO_DECL posix_event();
38 
39   // Destructor.
~posix_event()40   ~posix_event()
41   {
42     ::pthread_cond_destroy(&cond_);
43   }
44 
45   // Signal the event. (Retained for backward compatibility.)
46   template <typename Lock>
signal(Lock & lock)47   void signal(Lock& lock)
48   {
49     this->signal_all(lock);
50   }
51 
52   // Signal all waiters.
53   template <typename Lock>
signal_all(Lock & lock)54   void signal_all(Lock& lock)
55   {
56     BOOST_ASIO_ASSERT(lock.locked());
57     (void)lock;
58     state_ |= 1;
59     ::pthread_cond_broadcast(&cond_); // Ignore EINVAL.
60   }
61 
62   // Unlock the mutex and signal one waiter.
63   template <typename Lock>
unlock_and_signal_one(Lock & lock)64   void unlock_and_signal_one(Lock& lock)
65   {
66     BOOST_ASIO_ASSERT(lock.locked());
67     state_ |= 1;
68     bool have_waiters = (state_ > 1);
69     lock.unlock();
70     if (have_waiters)
71       ::pthread_cond_signal(&cond_); // Ignore EINVAL.
72   }
73 
74   // If there's a waiter, unlock the mutex and signal it.
75   template <typename Lock>
maybe_unlock_and_signal_one(Lock & lock)76   bool maybe_unlock_and_signal_one(Lock& lock)
77   {
78     BOOST_ASIO_ASSERT(lock.locked());
79     state_ |= 1;
80     if (state_ > 1)
81     {
82       lock.unlock();
83       ::pthread_cond_signal(&cond_); // Ignore EINVAL.
84       return true;
85     }
86     return false;
87   }
88 
89   // Reset the event.
90   template <typename Lock>
clear(Lock & lock)91   void clear(Lock& lock)
92   {
93     BOOST_ASIO_ASSERT(lock.locked());
94     (void)lock;
95     state_ &= ~std::size_t(1);
96   }
97 
98   // Wait for the event to become signalled.
99   template <typename Lock>
wait(Lock & lock)100   void wait(Lock& lock)
101   {
102     BOOST_ASIO_ASSERT(lock.locked());
103     while ((state_ & 1) == 0)
104     {
105       state_ += 2;
106       ::pthread_cond_wait(&cond_, &lock.mutex().mutex_); // Ignore EINVAL.
107       state_ -= 2;
108     }
109   }
110 
111 private:
112   ::pthread_cond_t cond_;
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/posix_event.ipp>
124 #endif // defined(BOOST_ASIO_HEADER_ONLY)
125 
126 #endif // defined(BOOST_ASIO_HAS_PTHREADS)
127 
128 #endif // BOOST_ASIO_DETAIL_POSIX_EVENT_HPP
129