1//
2// detail/posix_event.hpp
3// ~~~~~~~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2024 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 <cstddef>
23#include <pthread.h>
24#include <boost/asio/detail/assert.hpp>
25#include <boost/asio/detail/noncopyable.hpp>
26
27#include <boost/asio/detail/push_options.hpp>
28
29namespace boost {
30namespace asio {
31namespace detail {
32
33class posix_event
34 : private noncopyable
35{
36public:
37 // Constructor.
38 BOOST_ASIO_DECL posix_event();
39
40 // Destructor.
41 ~posix_event()
42 {
43 ::pthread_cond_destroy(cond: &cond_);
44 }
45
46 // Signal the event. (Retained for backward compatibility.)
47 template <typename Lock>
48 void signal(Lock& lock)
49 {
50 this->signal_all(lock);
51 }
52
53 // Signal all waiters.
54 template <typename Lock>
55 void signal_all(Lock& lock)
56 {
57 BOOST_ASIO_ASSERT(lock.locked());
58 (void)lock;
59 state_ |= 1;
60 ::pthread_cond_broadcast(cond: &cond_); // Ignore EINVAL.
61 }
62
63 // Unlock the mutex and signal one waiter.
64 template <typename Lock>
65 void unlock_and_signal_one(Lock& lock)
66 {
67 BOOST_ASIO_ASSERT(lock.locked());
68 state_ |= 1;
69 bool have_waiters = (state_ > 1);
70 lock.unlock();
71 if (have_waiters)
72 ::pthread_cond_signal(cond: &cond_); // Ignore EINVAL.
73 }
74
75 // Unlock the mutex and signal one waiter who may destroy us.
76 template <typename Lock>
77 void unlock_and_signal_one_for_destruction(Lock& lock)
78 {
79 BOOST_ASIO_ASSERT(lock.locked());
80 state_ |= 1;
81 bool have_waiters = (state_ > 1);
82 if (have_waiters)
83 ::pthread_cond_signal(cond: &cond_); // Ignore EINVAL.
84 lock.unlock();
85 }
86
87 // If there's a waiter, unlock the mutex and signal it.
88 template <typename Lock>
89 bool maybe_unlock_and_signal_one(Lock& lock)
90 {
91 BOOST_ASIO_ASSERT(lock.locked());
92 state_ |= 1;
93 if (state_ > 1)
94 {
95 lock.unlock();
96 ::pthread_cond_signal(cond: &cond_); // Ignore EINVAL.
97 return true;
98 }
99 return false;
100 }
101
102 // Reset the event.
103 template <typename Lock>
104 void clear(Lock& lock)
105 {
106 BOOST_ASIO_ASSERT(lock.locked());
107 (void)lock;
108 state_ &= ~std::size_t(1);
109 }
110
111 // Wait for the event to become signalled.
112 template <typename Lock>
113 void wait(Lock& lock)
114 {
115 BOOST_ASIO_ASSERT(lock.locked());
116 while ((state_ & 1) == 0)
117 {
118 state_ += 2;
119 ::pthread_cond_wait(cond: &cond_, mutex: &lock.mutex().mutex_); // Ignore EINVAL.
120 state_ -= 2;
121 }
122 }
123
124 // Timed wait for the event to become signalled.
125 template <typename Lock>
126 bool wait_for_usec(Lock& lock, long usec)
127 {
128 BOOST_ASIO_ASSERT(lock.locked());
129 if ((state_ & 1) == 0)
130 {
131 state_ += 2;
132 timespec ts;
133#if (defined(__MACH__) && defined(__APPLE__)) \
134 || (defined(__ANDROID__) && (__ANDROID_API__ < 21) \
135 && defined(HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE))
136 ts.tv_sec = usec / 1000000;
137 ts.tv_nsec = (usec % 1000000) * 1000;
138 ::pthread_cond_timedwait_relative_np(
139 &cond_, &lock.mutex().mutex_, &ts); // Ignore EINVAL.
140#else // (defined(__MACH__) && defined(__APPLE__))
141 // || (defined(__ANDROID__) && (__ANDROID_API__ < 21)
142 // && defined(HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE))
143 if (::clock_gettime(CLOCK_MONOTONIC, tp: &ts) == 0)
144 {
145 ts.tv_sec += usec / 1000000;
146 ts.tv_nsec += (usec % 1000000) * 1000;
147 ts.tv_sec += ts.tv_nsec / 1000000000;
148 ts.tv_nsec = ts.tv_nsec % 1000000000;
149 ::pthread_cond_timedwait(cond: &cond_,
150 mutex: &lock.mutex().mutex_, abstime: &ts); // Ignore EINVAL.
151 }
152#endif // (defined(__MACH__) && defined(__APPLE__))
153 // || (defined(__ANDROID__) && (__ANDROID_API__ < 21)
154 // && defined(HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE))
155 state_ -= 2;
156 }
157 return (state_ & 1) != 0;
158 }
159
160private:
161 ::pthread_cond_t cond_;
162 std::size_t state_;
163};
164
165} // namespace detail
166} // namespace asio
167} // namespace boost
168
169#include <boost/asio/detail/pop_options.hpp>
170
171#if defined(BOOST_ASIO_HEADER_ONLY)
172# include <boost/asio/detail/impl/posix_event.ipp>
173#endif // defined(BOOST_ASIO_HEADER_ONLY)
174
175#endif // defined(BOOST_ASIO_HAS_PTHREADS)
176
177#endif // BOOST_ASIO_DETAIL_POSIX_EVENT_HPP
178

source code of boost/libs/asio/include/boost/asio/detail/posix_event.hpp