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1 | // Distributed under the Boost Software License, Version 1.0. (See |
2 | // accompanying file LICENSE_1_0.txt or copy at | |
3 | // http://www.boost.org/LICENSE_1_0.txt) | |
4 | // (C) Copyright 2013 Vicente J. Botet Escriba | |
5 | ||
6 | #ifndef BOOST_THREAD_COMPLETION_LATCH_HPP | |
7 | #define BOOST_THREAD_COMPLETION_LATCH_HPP | |
8 | ||
9 | #include <boost/thread/detail/config.hpp> | |
10 | #include <boost/thread/detail/delete.hpp> | |
11 | #include <boost/thread/detail/counter.hpp> | |
12 | ||
13 | #include <boost/thread/mutex.hpp> | |
14 | #include <boost/thread/lock_types.hpp> | |
15 | #include <boost/thread/condition_variable.hpp> | |
16 | #include <boost/chrono/duration.hpp> | |
17 | #include <boost/chrono/time_point.hpp> | |
18 | #include <boost/assert.hpp> | |
19 | //#include <boost/thread/detail/nullary_function.hpp> | |
20 | #include <boost/thread/csbl/functional.hpp> | |
21 | ||
22 | #include <boost/config/abi_prefix.hpp> | |
23 | ||
24 | namespace boost | |
25 | { | |
26 | namespace thread_detail | |
27 | { | |
28 | void noop() | |
29 | { | |
30 | } | |
31 | } | |
32 | class completion_latch | |
33 | { | |
34 | public: | |
35 | /// the implementation defined completion function type | |
36 | //typedef detail::nullary_function<void()> completion_function; | |
37 | typedef csbl::function<void()> completion_function; | |
38 | /// noop completion function factory | |
39 | static completion_function noop() | |
40 | { | |
41 | return completion_function(&thread_detail::noop); | |
42 | } | |
43 | ||
44 | private: | |
45 | struct around_wait; | |
46 | friend struct around_wait; | |
47 | struct around_wait | |
48 | { | |
49 | completion_latch &that_; | |
50 | boost::unique_lock<boost::mutex> &lk_; | |
51 | around_wait(completion_latch &that, boost::unique_lock<boost::mutex> &lk) | |
52 | : that_(that), lk_(lk) | |
53 | { | |
54 | that_.leavers_.cond_.wait(lk, detail::counter_is_zero(that_.leavers_)); | |
55 | that_.waiters_.inc_and_notify_all(); | |
56 | that_.leavers_.cond_.wait(lk, detail::counter_is_not_zero(that_.leavers_)); | |
57 | } | |
58 | ~around_wait() | |
59 | { | |
60 | that_.waiters_.dec_and_notify_all(); | |
61 | } | |
62 | }; | |
63 | ||
64 | bool count_down(unique_lock<mutex> &lk) | |
65 | { | |
66 | BOOST_ASSERT(count_ > 0); | |
67 | if (--count_ == 0) | |
68 | { | |
69 | waiters_.cond_.wait(lk, detail::counter_is_not_zero(waiters_)); | |
70 | leavers_.assign_and_notify_all(waiters_); | |
71 | count_.cond_.notify_all(); | |
72 | waiters_.cond_.wait(lk, detail::counter_is_zero(waiters_)); | |
73 | leavers_.assign_and_notify_all(0); | |
74 | lk.unlock(); | |
75 | funct_(); | |
76 | return true; | |
77 | } | |
78 | return false; | |
79 | } | |
80 | ||
81 | public: | |
82 | BOOST_THREAD_NO_COPYABLE( completion_latch ) | |
83 | ||
84 | /// Constructs a latch with a given count. | |
85 | completion_latch(std::size_t count) : | |
86 | count_(count), funct_(noop()), waiters_(0), leavers_(0) | |
87 | { | |
88 | } | |
89 | ||
90 | /// Constructs a latch with a given count and a completion function. | |
91 | template <typename F> | |
92 | completion_latch(std::size_t count, BOOST_THREAD_RV_REF(F) funct) : | |
93 | count_(count), | |
94 | funct_(boost::move(funct)), | |
95 | waiters_(0), | |
96 | leavers_(0) | |
97 | { | |
98 | } | |
99 | completion_latch(std::size_t count, void(*funct)()) : | |
100 | count_(count), funct_(funct), waiters_(0), leavers_(0) | |
101 | { | |
102 | } | |
103 | ||
104 | /// | |
105 | ~completion_latch() | |
106 | { | |
107 | } | |
108 | ||
109 | /// Blocks until the latch has counted down to zero. | |
110 | void wait() | |
111 | { | |
112 | boost::unique_lock<boost::mutex> lk(mutex_); | |
113 | around_wait aw(*this, lk); | |
114 | count_.cond_.wait(lk, detail::counter_is_zero(count_)); | |
115 | } | |
116 | ||
117 | /// @return true if the internal counter is already 0, false otherwise | |
118 | bool try_wait() | |
119 | { | |
120 | boost::unique_lock<boost::mutex> lk(mutex_); | |
121 | around_wait aw(*this, lk); | |
122 | return (count_ == 0); | |
123 | } | |
124 | ||
125 | /// try to wait for a specified amount of time | |
126 | /// @return whether there is a timeout or not. | |
127 | template <class Rep, class Period> | |
128 | cv_status wait_for(const chrono::duration<Rep, Period>& rel_time) | |
129 | { | |
130 | boost::unique_lock<boost::mutex> lk(mutex_); | |
131 | around_wait aw(*this, lk); | |
132 | return count_.cond_.wait_for(lk, rel_time, detail::counter_is_zero(count_)) | |
133 | ? cv_status::no_timeout | |
134 | : cv_status::timeout; | |
135 | } | |
136 | ||
137 | /// try to wait until the specified time_point is reached | |
138 | /// @return whether there is a timeout or not. | |
139 | template <class Clock, class Duration> | |
140 | cv_status wait_until(const chrono::time_point<Clock, Duration>& abs_time) | |
141 | { | |
142 | boost::unique_lock<boost::mutex> lk(mutex_); | |
143 | around_wait aw(*this, lk); | |
144 | return count_.cond_.wait_until(lk, abs_time, detail::counter_is_zero(count_)) | |
145 | ? cv_status::no_timeout | |
146 | : cv_status::timeout; | |
147 | } | |
148 | ||
149 | /// Decrement the count and notify anyone waiting if we reach zero. | |
150 | /// @Requires count must be greater than 0 | |
151 | void count_down() | |
152 | { | |
153 | unique_lock<mutex> lk(mutex_); | |
154 | count_down(lk); | |
155 | } | |
156 | void signal() | |
157 | { | |
158 | count_down(); | |
159 | } | |
160 | ||
161 | /// Decrement the count and notify anyone waiting if we reach zero. | |
162 | /// Blocks until the latch has counted down to zero. | |
163 | /// @Requires count must be greater than 0 | |
164 | void count_down_and_wait() | |
165 | { | |
166 | boost::unique_lock<boost::mutex> lk(mutex_); | |
167 | if (count_down(lk)) | |
168 | { | |
169 | return; | |
170 | } | |
171 | around_wait aw(*this, lk); | |
172 | count_.cond_.wait(lk, detail::counter_is_zero(count_)); | |
173 | } | |
174 | void sync() | |
175 | { | |
176 | count_down_and_wait(); | |
177 | } | |
178 | ||
179 | /// Reset the counter | |
180 | /// #Requires This method may only be invoked when there are no other threads currently inside the count_down_and_wait() method. | |
181 | void reset(std::size_t count) | |
182 | { | |
183 | boost::lock_guard<boost::mutex> lk(mutex_); | |
184 | //BOOST_ASSERT(count_ == 0); | |
185 | count_ = count; | |
186 | } | |
187 | ||
188 | /// Resets the latch with the new completion function. | |
189 | /// The next time the internal count reaches 0, this function will be invoked. | |
190 | /// This completion function may only be invoked when there are no other threads | |
191 | /// currently inside the count_down and wait related functions. | |
192 | /// It may also be invoked from within the registered completion function. | |
193 | /// @Returns the old completion function if any or noop if | |
194 | ||
195 | #ifdef BOOST_NO_CXX11_HDR_FUNCTIONAL | |
196 | template <typename F> | |
197 | completion_function then(BOOST_THREAD_RV_REF(F) funct) | |
198 | { | |
199 | boost::lock_guard<boost::mutex> lk(mutex_); | |
200 | completion_function tmp(funct_); | |
201 | funct_ = boost::move(funct); | |
202 | return tmp; | |
203 | } | |
204 | #endif | |
205 | completion_function then(void(*funct)()) | |
206 | { | |
207 | boost::lock_guard<boost::mutex> lk(mutex_); | |
208 | completion_function tmp(funct_); | |
209 | funct_ = completion_function(funct); | |
210 | return tmp; | |
211 | } | |
212 | ||
213 | private: | |
214 | mutex mutex_; | |
215 | detail::counter count_; | |
216 | completion_function funct_; | |
217 | detail::counter waiters_; | |
218 | detail::counter leavers_; | |
219 | }; | |
220 | ||
221 | } // namespace boost | |
222 | ||
223 | #include <boost/config/abi_suffix.hpp> | |
224 | ||
225 | #endif |