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1 /*
2  * Copyright (c) 2008-2012 Niels Provos, Nick Mathewson
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  * 3. The name of the author may not be used to endorse or promote products
13  *    derived from this software without specific prior written permission.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 #ifndef _EVTHREAD_INTERNAL_H_
27 #define _EVTHREAD_INTERNAL_H_
28 
29 #ifdef __cplusplus
30 extern "C" {
31 #endif
32 
33 #include "event2/thread.h"
34 #include "event2/event-config.h"
35 #include "util-internal.h"
36 
37 struct event_base;
38 
39 #ifndef WIN32
40 /* On Windows, the way we currently make DLLs, it's not allowed for us to
41  * have shared global structures.  Thus, we only do the direct-call-to-function
42  * code path if we know that the local shared library system supports it.
43  */
44 #define EVTHREAD_EXPOSE_STRUCTS
45 #endif
46 
47 #if ! defined(_EVENT_DISABLE_THREAD_SUPPORT) && defined(EVTHREAD_EXPOSE_STRUCTS)
48 /* Global function pointers to lock-related functions. NULL if locking isn't
49    enabled. */
50 extern struct evthread_lock_callbacks _evthread_lock_fns;
51 extern struct evthread_condition_callbacks _evthread_cond_fns;
52 extern unsigned long (*_evthread_id_fn)(void);
53 extern int _evthread_lock_debugging_enabled;
54 
55 /** Return the ID of the current thread, or 1 if threading isn't enabled. */
56 #define EVTHREAD_GET_ID() \
57 	(_evthread_id_fn ? _evthread_id_fn() : 1)
58 
59 /** Return true iff we're in the thread that is currently (or most recently)
60  * running a given event_base's loop. Requires lock. */
61 #define EVBASE_IN_THREAD(base)				 \
62 	(_evthread_id_fn == NULL ||			 \
63 	(base)->th_owner_id == _evthread_id_fn())
64 
65 /** Return true iff we need to notify the base's main thread about changes to
66  * its state, because it's currently running the main loop in another
67  * thread. Requires lock. */
68 #define EVBASE_NEED_NOTIFY(base)			 \
69 	(_evthread_id_fn != NULL &&			 \
70 	    (base)->running_loop &&			 \
71 	    (base)->th_owner_id != _evthread_id_fn())
72 
73 /** Allocate a new lock, and store it in lockvar, a void*.  Sets lockvar to
74     NULL if locking is not enabled. */
75 #define EVTHREAD_ALLOC_LOCK(lockvar, locktype)		\
76 	((lockvar) = _evthread_lock_fns.alloc ?		\
77 	    _evthread_lock_fns.alloc(locktype) : NULL)
78 
79 /** Free a given lock, if it is present and locking is enabled. */
80 #define EVTHREAD_FREE_LOCK(lockvar, locktype)				\
81 	do {								\
82 		void *_lock_tmp_ = (lockvar);				\
83 		if (_lock_tmp_ && _evthread_lock_fns.free)		\
84 			_evthread_lock_fns.free(_lock_tmp_, (locktype)); \
85 	} while (0)
86 
87 /** Acquire a lock. */
88 #define EVLOCK_LOCK(lockvar,mode)					\
89 	do {								\
90 		if (lockvar)						\
91 			_evthread_lock_fns.lock(mode, lockvar);		\
92 	} while (0)
93 
94 /** Release a lock */
95 #define EVLOCK_UNLOCK(lockvar,mode)					\
96 	do {								\
97 		if (lockvar)						\
98 			_evthread_lock_fns.unlock(mode, lockvar);	\
99 	} while (0)
100 
101 /** Helper: put lockvar1 and lockvar2 into pointerwise ascending order. */
102 #define _EVLOCK_SORTLOCKS(lockvar1, lockvar2)				\
103 	do {								\
104 		if (lockvar1 && lockvar2 && lockvar1 > lockvar2) {	\
105 			void *tmp = lockvar1;				\
106 			lockvar1 = lockvar2;				\
107 			lockvar2 = tmp;					\
108 		}							\
109 	} while (0)
110 
111 /** Lock an event_base, if it is set up for locking.  Acquires the lock
112     in the base structure whose field is named 'lockvar'. */
113 #define EVBASE_ACQUIRE_LOCK(base, lockvar) do {				\
114 		EVLOCK_LOCK((base)->lockvar, 0);			\
115 	} while (0)
116 
117 /** Unlock an event_base, if it is set up for locking. */
118 #define EVBASE_RELEASE_LOCK(base, lockvar) do {				\
119 		EVLOCK_UNLOCK((base)->lockvar, 0);			\
120 	} while (0)
121 
122 /** If lock debugging is enabled, and lock is non-null, assert that 'lock' is
123  * locked and held by us. */
124 #define EVLOCK_ASSERT_LOCKED(lock)					\
125 	do {								\
126 		if ((lock) && _evthread_lock_debugging_enabled) {	\
127 			EVUTIL_ASSERT(_evthread_is_debug_lock_held(lock)); \
128 		}							\
129 	} while (0)
130 
131 /** Try to grab the lock for 'lockvar' without blocking, and return 1 if we
132  * manage to get it. */
133 static inline int EVLOCK_TRY_LOCK(void *lock);
134 static inline int
EVLOCK_TRY_LOCK(void * lock)135 EVLOCK_TRY_LOCK(void *lock)
136 {
137 	if (lock && _evthread_lock_fns.lock) {
138 		int r = _evthread_lock_fns.lock(EVTHREAD_TRY, lock);
139 		return !r;
140 	} else {
141 		/* Locking is disabled either globally or for this thing;
142 		 * of course we count as having the lock. */
143 		return 1;
144 	}
145 }
146 
147 /** Allocate a new condition variable and store it in the void *, condvar */
148 #define EVTHREAD_ALLOC_COND(condvar)					\
149 	do {								\
150 		(condvar) = _evthread_cond_fns.alloc_condition ?	\
151 		    _evthread_cond_fns.alloc_condition(0) : NULL;	\
152 	} while (0)
153 /** Deallocate and free a condition variable in condvar */
154 #define EVTHREAD_FREE_COND(cond)					\
155 	do {								\
156 		if (cond)						\
157 			_evthread_cond_fns.free_condition((cond));	\
158 	} while (0)
159 /** Signal one thread waiting on cond */
160 #define EVTHREAD_COND_SIGNAL(cond)					\
161 	( (cond) ? _evthread_cond_fns.signal_condition((cond), 0) : 0 )
162 /** Signal all threads waiting on cond */
163 #define EVTHREAD_COND_BROADCAST(cond)					\
164 	( (cond) ? _evthread_cond_fns.signal_condition((cond), 1) : 0 )
165 /** Wait until the condition 'cond' is signalled.  Must be called while
166  * holding 'lock'.  The lock will be released until the condition is
167  * signalled, at which point it will be acquired again.  Returns 0 for
168  * success, -1 for failure. */
169 #define EVTHREAD_COND_WAIT(cond, lock)					\
170 	( (cond) ? _evthread_cond_fns.wait_condition((cond), (lock), NULL) : 0 )
171 /** As EVTHREAD_COND_WAIT, but gives up after 'tv' has elapsed.  Returns 1
172  * on timeout. */
173 #define EVTHREAD_COND_WAIT_TIMED(cond, lock, tv)			\
174 	( (cond) ? _evthread_cond_fns.wait_condition((cond), (lock), (tv)) : 0 )
175 
176 /** True iff locking functions have been configured. */
177 #define EVTHREAD_LOCKING_ENABLED()		\
178 	(_evthread_lock_fns.lock != NULL)
179 
180 #elif ! defined(_EVENT_DISABLE_THREAD_SUPPORT)
181 
182 unsigned long _evthreadimpl_get_id(void);
183 int _evthreadimpl_is_lock_debugging_enabled(void);
184 void *_evthreadimpl_lock_alloc(unsigned locktype);
185 void _evthreadimpl_lock_free(void *lock, unsigned locktype);
186 int _evthreadimpl_lock_lock(unsigned mode, void *lock);
187 int _evthreadimpl_lock_unlock(unsigned mode, void *lock);
188 void *_evthreadimpl_cond_alloc(unsigned condtype);
189 void _evthreadimpl_cond_free(void *cond);
190 int _evthreadimpl_cond_signal(void *cond, int broadcast);
191 int _evthreadimpl_cond_wait(void *cond, void *lock, const struct timeval *tv);
192 int _evthreadimpl_locking_enabled(void);
193 
194 #define EVTHREAD_GET_ID() _evthreadimpl_get_id()
195 #define EVBASE_IN_THREAD(base)				\
196 	((base)->th_owner_id == _evthreadimpl_get_id())
197 #define EVBASE_NEED_NOTIFY(base)			 \
198 	((base)->running_loop &&			 \
199 	    ((base)->th_owner_id != _evthreadimpl_get_id()))
200 
201 #define EVTHREAD_ALLOC_LOCK(lockvar, locktype)		\
202 	((lockvar) = _evthreadimpl_lock_alloc(locktype))
203 
204 #define EVTHREAD_FREE_LOCK(lockvar, locktype)				\
205 	do {								\
206 		void *_lock_tmp_ = (lockvar);				\
207 		if (_lock_tmp_)						\
208 			_evthreadimpl_lock_free(_lock_tmp_, (locktype)); \
209 	} while (0)
210 
211 /** Acquire a lock. */
212 #define EVLOCK_LOCK(lockvar,mode)					\
213 	do {								\
214 		if (lockvar)						\
215 			_evthreadimpl_lock_lock(mode, lockvar);		\
216 	} while (0)
217 
218 /** Release a lock */
219 #define EVLOCK_UNLOCK(lockvar,mode)					\
220 	do {								\
221 		if (lockvar)						\
222 			_evthreadimpl_lock_unlock(mode, lockvar);	\
223 	} while (0)
224 
225 /** Lock an event_base, if it is set up for locking.  Acquires the lock
226     in the base structure whose field is named 'lockvar'. */
227 #define EVBASE_ACQUIRE_LOCK(base, lockvar) do {				\
228 		EVLOCK_LOCK((base)->lockvar, 0);			\
229 	} while (0)
230 
231 /** Unlock an event_base, if it is set up for locking. */
232 #define EVBASE_RELEASE_LOCK(base, lockvar) do {				\
233 		EVLOCK_UNLOCK((base)->lockvar, 0);			\
234 	} while (0)
235 
236 /** If lock debugging is enabled, and lock is non-null, assert that 'lock' is
237  * locked and held by us. */
238 #define EVLOCK_ASSERT_LOCKED(lock)					\
239 	do {								\
240 		if ((lock) && _evthreadimpl_is_lock_debugging_enabled()) { \
241 			EVUTIL_ASSERT(_evthread_is_debug_lock_held(lock)); \
242 		}							\
243 	} while (0)
244 
245 /** Try to grab the lock for 'lockvar' without blocking, and return 1 if we
246  * manage to get it. */
247 static inline int EVLOCK_TRY_LOCK(void *lock);
248 static inline int
EVLOCK_TRY_LOCK(void * lock)249 EVLOCK_TRY_LOCK(void *lock)
250 {
251 	if (lock) {
252 		int r = _evthreadimpl_lock_lock(EVTHREAD_TRY, lock);
253 		return !r;
254 	} else {
255 		/* Locking is disabled either globally or for this thing;
256 		 * of course we count as having the lock. */
257 		return 1;
258 	}
259 }
260 
261 /** Allocate a new condition variable and store it in the void *, condvar */
262 #define EVTHREAD_ALLOC_COND(condvar)					\
263 	do {								\
264 		(condvar) = _evthreadimpl_cond_alloc(0);		\
265 	} while (0)
266 /** Deallocate and free a condition variable in condvar */
267 #define EVTHREAD_FREE_COND(cond)					\
268 	do {								\
269 		if (cond)						\
270 			_evthreadimpl_cond_free((cond));		\
271 	} while (0)
272 /** Signal one thread waiting on cond */
273 #define EVTHREAD_COND_SIGNAL(cond)					\
274 	( (cond) ? _evthreadimpl_cond_signal((cond), 0) : 0 )
275 /** Signal all threads waiting on cond */
276 #define EVTHREAD_COND_BROADCAST(cond)					\
277 	( (cond) ? _evthreadimpl_cond_signal((cond), 1) : 0 )
278 /** Wait until the condition 'cond' is signalled.  Must be called while
279  * holding 'lock'.  The lock will be released until the condition is
280  * signalled, at which point it will be acquired again.  Returns 0 for
281  * success, -1 for failure. */
282 #define EVTHREAD_COND_WAIT(cond, lock)					\
283 	( (cond) ? _evthreadimpl_cond_wait((cond), (lock), NULL) : 0 )
284 /** As EVTHREAD_COND_WAIT, but gives up after 'tv' has elapsed.  Returns 1
285  * on timeout. */
286 #define EVTHREAD_COND_WAIT_TIMED(cond, lock, tv)			\
287 	( (cond) ? _evthreadimpl_cond_wait((cond), (lock), (tv)) : 0 )
288 
289 #define EVTHREAD_LOCKING_ENABLED()		\
290 	(_evthreadimpl_locking_enabled())
291 
292 #else /* _EVENT_DISABLE_THREAD_SUPPORT */
293 
294 #define EVTHREAD_GET_ID()	1
295 #define EVTHREAD_ALLOC_LOCK(lockvar, locktype) _EVUTIL_NIL_STMT
296 #define EVTHREAD_FREE_LOCK(lockvar, locktype) _EVUTIL_NIL_STMT
297 
298 #define EVLOCK_LOCK(lockvar, mode) _EVUTIL_NIL_STMT
299 #define EVLOCK_UNLOCK(lockvar, mode) _EVUTIL_NIL_STMT
300 #define EVLOCK_LOCK2(lock1,lock2,mode1,mode2) _EVUTIL_NIL_STMT
301 #define EVLOCK_UNLOCK2(lock1,lock2,mode1,mode2) _EVUTIL_NIL_STMT
302 
303 #define EVBASE_IN_THREAD(base)	1
304 #define EVBASE_NEED_NOTIFY(base) 0
305 #define EVBASE_ACQUIRE_LOCK(base, lock) _EVUTIL_NIL_STMT
306 #define EVBASE_RELEASE_LOCK(base, lock) _EVUTIL_NIL_STMT
307 #define EVLOCK_ASSERT_LOCKED(lock) _EVUTIL_NIL_STMT
308 
309 #define EVLOCK_TRY_LOCK(lock) 1
310 
311 #define EVTHREAD_ALLOC_COND(condvar) _EVUTIL_NIL_STMT
312 #define EVTHREAD_FREE_COND(cond) _EVUTIL_NIL_STMT
313 #define EVTHREAD_COND_SIGNAL(cond) _EVUTIL_NIL_STMT
314 #define EVTHREAD_COND_BROADCAST(cond) _EVUTIL_NIL_STMT
315 #define EVTHREAD_COND_WAIT(cond, lock) _EVUTIL_NIL_STMT
316 #define EVTHREAD_COND_WAIT_TIMED(cond, lock, howlong) _EVUTIL_NIL_STMT
317 
318 #define EVTHREAD_LOCKING_ENABLED() 0
319 
320 #endif
321 
322 /* This code is shared between both lock impls */
323 #if ! defined(_EVENT_DISABLE_THREAD_SUPPORT)
324 /** Helper: put lockvar1 and lockvar2 into pointerwise ascending order. */
325 #define _EVLOCK_SORTLOCKS(lockvar1, lockvar2)				\
326 	do {								\
327 		if (lockvar1 && lockvar2 && lockvar1 > lockvar2) {	\
328 			void *tmp = lockvar1;				\
329 			lockvar1 = lockvar2;				\
330 			lockvar2 = tmp;					\
331 		}							\
332 	} while (0)
333 
334 /** Acquire both lock1 and lock2.  Always allocates locks in the same order,
335  * so that two threads locking two locks with LOCK2 will not deadlock. */
336 #define EVLOCK_LOCK2(lock1,lock2,mode1,mode2)				\
337 	do {								\
338 		void *_lock1_tmplock = (lock1);				\
339 		void *_lock2_tmplock = (lock2);				\
340 		_EVLOCK_SORTLOCKS(_lock1_tmplock,_lock2_tmplock);	\
341 		EVLOCK_LOCK(_lock1_tmplock,mode1);			\
342 		if (_lock2_tmplock != _lock1_tmplock)			\
343 			EVLOCK_LOCK(_lock2_tmplock,mode2);		\
344 	} while (0)
345 /** Release both lock1 and lock2.  */
346 #define EVLOCK_UNLOCK2(lock1,lock2,mode1,mode2)				\
347 	do {								\
348 		void *_lock1_tmplock = (lock1);				\
349 		void *_lock2_tmplock = (lock2);				\
350 		_EVLOCK_SORTLOCKS(_lock1_tmplock,_lock2_tmplock);	\
351 		if (_lock2_tmplock != _lock1_tmplock)			\
352 			EVLOCK_UNLOCK(_lock2_tmplock,mode2);		\
353 		EVLOCK_UNLOCK(_lock1_tmplock,mode1);			\
354 	} while (0)
355 
356 int _evthread_is_debug_lock_held(void *lock);
357 void *_evthread_debug_get_real_lock(void *lock);
358 
359 void *evthread_setup_global_lock_(void *lock_, unsigned locktype,
360     int enable_locks);
361 
362 #define EVTHREAD_SETUP_GLOBAL_LOCK(lockvar, locktype)			\
363 	do {								\
364 		lockvar = evthread_setup_global_lock_(lockvar,		\
365 		    (locktype), enable_locks);				\
366 		if (!lockvar) {						\
367 			event_warn("Couldn't allocate %s", #lockvar);	\
368 			return -1;					\
369 		}							\
370 	} while (0);
371 
372 int event_global_setup_locks_(const int enable_locks);
373 int evsig_global_setup_locks_(const int enable_locks);
374 int evutil_secure_rng_global_setup_locks_(const int enable_locks);
375 
376 #endif
377 
378 #ifdef __cplusplus
379 }
380 #endif
381 
382 #endif /* _EVTHREAD_INTERNAL_H_ */
383