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1 | ////////////////////////////////////////////////////////////////////////////// |
2 | // | |
3 | // (C) Copyright Ion Gaztanaga 2005-2012. Distributed under the Boost | |
4 | // Software License, Version 1.0. (See accompanying file | |
5 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
6 | // | |
7 | // See http://www.boost.org/libs/interprocess for documentation. | |
8 | // | |
9 | ////////////////////////////////////////////////////////////////////////////// | |
10 | ||
11 | #ifndef BOOST_INTERPROCESS_DETAIL_CONDITION_ALGORITHM_8A_HPP | |
12 | #define BOOST_INTERPROCESS_DETAIL_CONDITION_ALGORITHM_8A_HPP | |
13 | ||
14 | #ifndef BOOST_CONFIG_HPP | |
15 | # include <boost/config.hpp> | |
16 | #endif | |
17 | # | |
18 | #if defined(BOOST_HAS_PRAGMA_ONCE) | |
19 | # pragma once | |
20 | #endif | |
21 | ||
22 | #include <boost/interprocess/detail/config_begin.hpp> | |
23 | #include <boost/interprocess/detail/workaround.hpp> | |
24 | #include <boost/interprocess/sync/scoped_lock.hpp> | |
25 | #include <boost/interprocess/sync/detail/locks.hpp> | |
26 | #include <limits> | |
27 | ||
28 | namespace boost { | |
29 | namespace interprocess { | |
30 | namespace ipcdetail { | |
31 | ||
32 | //////////////////////////////////////////////////////////////////////// | |
33 | //////////////////////////////////////////////////////////////////////// | |
34 | //////////////////////////////////////////////////////////////////////// | |
35 | // | |
36 | // Condition variable algorithm taken from pthreads-win32 discussion. | |
37 | // | |
38 | // The algorithm was developed by Alexander Terekhov in colaboration with | |
39 | // Louis Thomas. | |
40 | // | |
41 | // Algorithm 8a / IMPL_SEM,UNBLOCK_STRATEGY == UNBLOCK_ALL | |
42 | // | |
43 | // semBlockLock - bin.semaphore | |
44 | // semBlockQueue - semaphore | |
45 | // mtxExternal - mutex or CS | |
46 | // mtxUnblockLock - mutex or CS | |
47 | // nWaitersGone - int | |
48 | // nWaitersBlocked - int | |
49 | // nWaitersToUnblock - int | |
50 | // | |
51 | // wait( timeout ) { | |
52 | // | |
53 | // [auto: register int result ] // error checking omitted | |
54 | // [auto: register int nSignalsWasLeft ] | |
55 | // [auto: register int nWaitersWasGone ] | |
56 | // | |
57 | // sem_wait( semBlockLock ); | |
58 | // nWaitersBlocked++; | |
59 | // sem_post( semBlockLock ); | |
60 | // | |
61 | // unlock( mtxExternal ); | |
62 | // bTimedOut = sem_wait( semBlockQueue,timeout ); | |
63 | // | |
64 | // lock( mtxUnblockLock ); | |
65 | // if ( 0 != (nSignalsWasLeft = nWaitersToUnblock) ) { | |
66 | // if ( bTimedOut ) { // timeout (or canceled) | |
67 | // if ( 0 != nWaitersBlocked ) { | |
68 | // nWaitersBlocked--; | |
69 | // } | |
70 | // else { | |
71 | // nWaitersGone++; // count spurious wakeups. | |
72 | // } | |
73 | // } | |
74 | // if ( 0 == --nWaitersToUnblock ) { | |
75 | // if ( 0 != nWaitersBlocked ) { | |
76 | // sem_post( semBlockLock ); // open the gate. | |
77 | // nSignalsWasLeft = 0; // do not open the gate | |
78 | // // below again. | |
79 | // } | |
80 | // else if ( 0 != (nWaitersWasGone = nWaitersGone) ) { | |
81 | // nWaitersGone = 0; | |
82 | // } | |
83 | // } | |
84 | // } | |
85 | // else if ( INT_MAX/2 == ++nWaitersGone ) { // timeout/canceled or | |
86 | // // spurious semaphore :-) | |
87 | // sem_wait( semBlockLock ); | |
88 | // nWaitersBlocked -= nWaitersGone; // something is going on here | |
89 | // // - test of timeouts? :-) | |
90 | // sem_post( semBlockLock ); | |
91 | // nWaitersGone = 0; | |
92 | // } | |
93 | // unlock( mtxUnblockLock ); | |
94 | // | |
95 | // if ( 1 == nSignalsWasLeft ) { | |
96 | // if ( 0 != nWaitersWasGone ) { | |
97 | // // sem_adjust( semBlockQueue,-nWaitersWasGone ); | |
98 | // while ( nWaitersWasGone-- ) { | |
99 | // sem_wait( semBlockQueue ); // better now than spurious later | |
100 | // } | |
101 | // } sem_post( semBlockLock ); // open the gate | |
102 | // } | |
103 | // | |
104 | // lock( mtxExternal ); | |
105 | // | |
106 | // return ( bTimedOut ) ? ETIMEOUT : 0; | |
107 | // } | |
108 | // | |
109 | // signal(bAll) { | |
110 | // | |
111 | // [auto: register int result ] | |
112 | // [auto: register int nSignalsToIssue] | |
113 | // | |
114 | // lock( mtxUnblockLock ); | |
115 | // | |
116 | // if ( 0 != nWaitersToUnblock ) { // the gate is closed!!! | |
117 | // if ( 0 == nWaitersBlocked ) { // NO-OP | |
118 | // return unlock( mtxUnblockLock ); | |
119 | // } | |
120 | // if (bAll) { | |
121 | // nWaitersToUnblock += nSignalsToIssue=nWaitersBlocked; | |
122 | // nWaitersBlocked = 0; | |
123 | // } | |
124 | // else { | |
125 | // nSignalsToIssue = 1; | |
126 | // nWaitersToUnblock++; | |
127 | // nWaitersBlocked--; | |
128 | // } | |
129 | // } | |
130 | // else if ( nWaitersBlocked > nWaitersGone ) { // HARMLESS RACE CONDITION! | |
131 | // sem_wait( semBlockLock ); // close the gate | |
132 | // if ( 0 != nWaitersGone ) { | |
133 | // nWaitersBlocked -= nWaitersGone; | |
134 | // nWaitersGone = 0; | |
135 | // } | |
136 | // if (bAll) { | |
137 | // nSignalsToIssue = nWaitersToUnblock = nWaitersBlocked; | |
138 | // nWaitersBlocked = 0; | |
139 | // } | |
140 | // else { | |
141 | // nSignalsToIssue = nWaitersToUnblock = 1; | |
142 | // nWaitersBlocked--; | |
143 | // } | |
144 | // } | |
145 | // else { // NO-OP | |
146 | // return unlock( mtxUnblockLock ); | |
147 | // } | |
148 | // | |
149 | // unlock( mtxUnblockLock ); | |
150 | // sem_post( semBlockQueue,nSignalsToIssue ); | |
151 | // return result; | |
152 | // } | |
153 | //////////////////////////////////////////////////////////////////////// | |
154 | //////////////////////////////////////////////////////////////////////// | |
155 | //////////////////////////////////////////////////////////////////////// | |
156 | ||
157 | ||
158 | // Required interface for ConditionMembers | |
159 | // class ConditionMembers | |
160 | // { | |
161 | // typedef implementation_defined semaphore_type; | |
162 | // typedef implementation_defined mutex_type; | |
163 | // typedef implementation_defined integer_type; | |
164 | // | |
165 | // integer_type &get_nwaiters_blocked() | |
166 | // integer_type &get_nwaiters_gone() | |
167 | // integer_type &get_nwaiters_to_unblock() | |
168 | // semaphore_type &get_sem_block_queue() | |
169 | // semaphore_type &get_sem_block_lock() | |
170 | // mutex_type &get_mtx_unblock_lock() | |
171 | // }; | |
172 | // | |
173 | // Must be initialized as following | |
174 | // | |
175 | // get_nwaiters_blocked() == 0 | |
176 | // get_nwaiters_gone() == 0 | |
177 | // get_nwaiters_to_unblock() == 0 | |
178 | // get_sem_block_queue() == initial count 0 | |
179 | // get_sem_block_lock() == initial count 1 | |
180 | // get_mtx_unblock_lock() (unlocked) | |
181 | // | |
182 | template<class ConditionMembers> | |
183 | class condition_algorithm_8a | |
184 | { | |
185 | private: | |
186 | condition_algorithm_8a(); | |
187 | ~condition_algorithm_8a(); | |
188 | condition_algorithm_8a(const condition_algorithm_8a &); | |
189 | condition_algorithm_8a &operator=(const condition_algorithm_8a &); | |
190 | ||
191 | typedef typename ConditionMembers::semaphore_type semaphore_type; | |
192 | typedef typename ConditionMembers::mutex_type mutex_type; | |
193 | typedef typename ConditionMembers::integer_type integer_type; | |
194 | ||
195 | public: | |
196 | template<class Lock> | |
197 | static bool wait ( ConditionMembers &data, Lock &lock | |
198 | , bool timeout_enabled, const boost::posix_time::ptime &abs_time); | |
199 | static void signal(ConditionMembers &data, bool broadcast); | |
200 | }; | |
201 | ||
202 | template<class ConditionMembers> | |
203 | inline void condition_algorithm_8a<ConditionMembers>::signal(ConditionMembers &data, bool broadcast) | |
204 | { | |
205 | integer_type nsignals_to_issue; | |
206 | ||
207 | { | |
208 | scoped_lock<mutex_type> locker(data.get_mtx_unblock_lock()); | |
209 | ||
210 | if ( 0 != data.get_nwaiters_to_unblock() ) { // the gate is closed!!! | |
211 | if ( 0 == data.get_nwaiters_blocked() ) { // NO-OP | |
212 | //locker's destructor triggers data.get_mtx_unblock_lock().unlock() | |
213 | return; | |
214 | } | |
215 | if (broadcast) { | |
216 | data.get_nwaiters_to_unblock() += nsignals_to_issue = data.get_nwaiters_blocked(); | |
217 | data.get_nwaiters_blocked() = 0; | |
218 | } | |
219 | else { | |
220 | nsignals_to_issue = 1; | |
221 | data.get_nwaiters_to_unblock()++; | |
222 | data.get_nwaiters_blocked()--; | |
223 | } | |
224 | } | |
225 | else if ( data.get_nwaiters_blocked() > data.get_nwaiters_gone() ) { // HARMLESS RACE CONDITION! | |
226 | data.get_sem_block_lock().wait(); // close the gate | |
227 | if ( 0 != data.get_nwaiters_gone() ) { | |
228 | data.get_nwaiters_blocked() -= data.get_nwaiters_gone(); | |
229 | data.get_nwaiters_gone() = 0; | |
230 | } | |
231 | if (broadcast) { | |
232 | nsignals_to_issue = data.get_nwaiters_to_unblock() = data.get_nwaiters_blocked(); | |
233 | data.get_nwaiters_blocked() = 0; | |
234 | } | |
235 | else { | |
236 | nsignals_to_issue = data.get_nwaiters_to_unblock() = 1; | |
237 | data.get_nwaiters_blocked()--; | |
238 | } | |
239 | } | |
240 | else { // NO-OP | |
241 | //locker's destructor triggers data.get_mtx_unblock_lock().unlock() | |
242 | return; | |
243 | } | |
244 | //locker's destructor triggers data.get_mtx_unblock_lock().unlock() | |
245 | } | |
246 | data.get_sem_block_queue().post(nsignals_to_issue); | |
247 | } | |
248 | ||
249 | template<class ConditionMembers> | |
250 | template<class Lock> | |
251 | inline bool condition_algorithm_8a<ConditionMembers>::wait | |
252 | ( ConditionMembers &data | |
253 | , Lock &lock | |
254 | , bool tout_enabled | |
255 | , const boost::posix_time::ptime &abs_time | |
256 | ) | |
257 | { | |
258 | //Initialize to avoid warnings | |
259 | integer_type nsignals_was_left = 0; | |
260 | integer_type nwaiters_was_gone = 0; | |
261 | ||
262 | data.get_sem_block_lock().wait(); | |
263 | ++data.get_nwaiters_blocked(); | |
264 | data.get_sem_block_lock().post(); | |
265 | ||
266 | //Unlock external lock and program for relock | |
267 | lock_inverter<Lock> inverted_lock(lock); | |
268 | scoped_lock<lock_inverter<Lock> > external_unlock(inverted_lock); | |
269 | ||
270 | bool bTimedOut = tout_enabled | |
271 | ? !data.get_sem_block_queue().timed_wait(abs_time) | |
272 | : (data.get_sem_block_queue().wait(), false); | |
273 | ||
274 | { | |
275 | scoped_lock<mutex_type> locker(data.get_mtx_unblock_lock()); | |
276 | if ( 0 != (nsignals_was_left = data.get_nwaiters_to_unblock()) ) { | |
277 | if ( bTimedOut ) { // timeout (or canceled) | |
278 | if ( 0 != data.get_nwaiters_blocked() ) { | |
279 | data.get_nwaiters_blocked()--; | |
280 | } | |
281 | else { | |
282 | data.get_nwaiters_gone()++; // count spurious wakeups. | |
283 | } | |
284 | } | |
285 | if ( 0 == --data.get_nwaiters_to_unblock() ) { | |
286 | if ( 0 != data.get_nwaiters_blocked() ) { | |
287 | data.get_sem_block_lock().post(); // open the gate. | |
288 | nsignals_was_left = 0; // do not open the gate below again. | |
289 | } | |
290 | else if ( 0 != (nwaiters_was_gone = data.get_nwaiters_gone()) ) { | |
291 | data.get_nwaiters_gone() = 0; | |
292 | } | |
293 | } | |
294 | } | |
295 | else if ( (std::numeric_limits<integer_type>::max)()/2 | |
296 | == ++data.get_nwaiters_gone() ) { // timeout/canceled or spurious semaphore :-) | |
297 | data.get_sem_block_lock().wait(); | |
298 | data.get_nwaiters_blocked() -= data.get_nwaiters_gone(); // something is going on here - test of timeouts? :-) | |
299 | data.get_sem_block_lock().post(); | |
300 | data.get_nwaiters_gone() = 0; | |
301 | } | |
302 | //locker's destructor triggers data.get_mtx_unblock_lock().unlock() | |
303 | } | |
304 | ||
305 | if ( 1 == nsignals_was_left ) { | |
306 | if ( 0 != nwaiters_was_gone ) { | |
307 | // sem_adjust( data.get_sem_block_queue(),-nwaiters_was_gone ); | |
308 | while ( nwaiters_was_gone-- ) { | |
309 | data.get_sem_block_queue().wait(); // better now than spurious later | |
310 | } | |
311 | } | |
312 | data.get_sem_block_lock().post(); // open the gate | |
313 | } | |
314 | ||
315 | //lock.lock(); called from unlocker destructor | |
316 | ||
317 | return ( bTimedOut ) ? false : true; | |
318 | } | |
319 | ||
320 | ||
321 | template<class ConditionMembers> | |
322 | class condition_8a_wrapper | |
323 | { | |
324 | //Non-copyable | |
325 | condition_8a_wrapper(const condition_8a_wrapper &); | |
326 | condition_8a_wrapper &operator=(const condition_8a_wrapper &); | |
327 | ||
328 | ConditionMembers m_data; | |
329 | typedef ipcdetail::condition_algorithm_8a<ConditionMembers> algo_type; | |
330 | ||
331 | public: | |
332 | ||
333 | condition_8a_wrapper(){} | |
334 | ||
335 | //Compiler-generated destructor is OK | |
336 | //~condition_8a_wrapper(){} | |
337 | ||
338 | ConditionMembers & get_members() | |
339 | { return m_data; } | |
340 | ||
341 | const ConditionMembers & get_members() const | |
342 | { return m_data; } | |
343 | ||
344 | void notify_one() | |
345 | { algo_type::signal(m_data, false); } | |
346 | ||
347 | void notify_all() | |
348 | { algo_type::signal(m_data, true); } | |
349 | ||
350 | template <typename L> | |
351 | void wait(L& lock) | |
352 | { | |
353 | if (!lock) | |
354 | throw lock_exception(); | |
355 | algo_type::wait(m_data, lock, false, boost::posix_time::ptime()); | |
356 | } | |
357 | ||
358 | template <typename L, typename Pr> | |
359 | void wait(L& lock, Pr pred) | |
360 | { | |
361 | if (!lock) | |
362 | throw lock_exception(); | |
363 | ||
364 | while (!pred()) | |
365 | algo_type::wait(m_data, lock, false, boost::posix_time::ptime()); | |
366 | } | |
367 | ||
368 | template <typename L> | |
369 | bool timed_wait(L& lock, const boost::posix_time::ptime &abs_time) | |
370 | { | |
371 | if (!lock) | |
372 | throw lock_exception(); | |
373 | return algo_type::wait(m_data, lock, true, abs_time); | |
374 | } | |
375 | ||
376 | template <typename L, typename Pr> | |
377 | bool timed_wait(L& lock, const boost::posix_time::ptime &abs_time, Pr pred) | |
378 | { | |
379 | if (!lock) | |
380 | throw lock_exception(); | |
381 | while (!pred()){ | |
382 | if (!algo_type::wait(m_data, lock, true, abs_time)) | |
383 | return pred(); | |
384 | } | |
385 | return true; | |
386 | } | |
387 | }; | |
388 | ||
389 | } //namespace ipcdetail | |
390 | } //namespace interprocess | |
391 | } //namespace boost | |
392 | ||
393 | #include <boost/interprocess/detail/config_end.hpp> | |
394 | ||
395 | #endif //BOOST_INTERPROCESS_DETAIL_CONDITION_ALGORITHM_8A_HPP |