OpenMPI  0.1.1
evthread-internal.h
1 /*
2  * Copyright (c) 2008-2010 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
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 #elif ! defined(_EVENT_DISABLE_THREAD_SUPPORT)
177 
178 unsigned long _evthreadimpl_get_id(void);
179 int _evthreadimpl_is_lock_debugging_enabled(void);
180 void *_evthreadimpl_lock_alloc(unsigned locktype);
181 void _evthreadimpl_lock_free(void *lock, unsigned locktype);
182 int _evthreadimpl_lock_lock(unsigned mode, void *lock);
183 int _evthreadimpl_lock_unlock(unsigned mode, void *lock);
184 void *_evthreadimpl_cond_alloc(unsigned condtype);
185 void _evthreadimpl_cond_free(void *cond);
186 int _evthreadimpl_cond_signal(void *cond, int broadcast);
187 int _evthreadimpl_cond_wait(void *cond, void *lock, const struct timeval *tv);
188 
189 #define EVTHREAD_GET_ID() _evthreadimpl_get_id()
190 #define EVBASE_IN_THREAD(base) \
191  ((base)->th_owner_id == _evthreadimpl_get_id())
192 #define EVBASE_NEED_NOTIFY(base) \
193  ((base)->running_loop && \
194  ((base)->th_owner_id != _evthreadimpl_get_id()))
195 
196 #define EVTHREAD_ALLOC_LOCK(lockvar, locktype) \
197  ((lockvar) = _evthreadimpl_lock_alloc(locktype))
198 
199 #define EVTHREAD_FREE_LOCK(lockvar, locktype) \
200  do { \
201  void *_lock_tmp_ = (lockvar); \
202  if (_lock_tmp_) \
203  _evthreadimpl_lock_free(_lock_tmp_, (locktype)); \
204  } while (0)
205 
206 /** Acquire a lock. */
207 #define EVLOCK_LOCK(lockvar,mode) \
208  do { \
209  if (lockvar) \
210  _evthreadimpl_lock_lock(mode, lockvar); \
211  } while (0)
212 
213 /** Release a lock */
214 #define EVLOCK_UNLOCK(lockvar,mode) \
215  do { \
216  if (lockvar) \
217  _evthreadimpl_lock_unlock(mode, lockvar); \
218  } while (0)
219 
220 /** Lock an event_base, if it is set up for locking. Acquires the lock
221  in the base structure whose field is named 'lockvar'. */
222 #define EVBASE_ACQUIRE_LOCK(base, lockvar) do { \
223  EVLOCK_LOCK((base)->lockvar, 0); \
224  } while (0)
225 
226 /** Unlock an event_base, if it is set up for locking. */
227 #define EVBASE_RELEASE_LOCK(base, lockvar) do { \
228  EVLOCK_UNLOCK((base)->lockvar, 0); \
229  } while (0)
230 
231 /** If lock debugging is enabled, and lock is non-null, assert that 'lock' is
232  * locked and held by us. */
233 #define EVLOCK_ASSERT_LOCKED(lock) \
234  do { \
235  if ((lock) && _evthreadimpl_is_lock_debugging_enabled()) { \
236  EVUTIL_ASSERT(_evthread_is_debug_lock_held(lock)); \
237  } \
238  } while (0)
239 
240 /** Try to grab the lock for 'lockvar' without blocking, and return 1 if we
241  * manage to get it. */
242 static inline int EVLOCK_TRY_LOCK(void *lock);
243 static inline int
244 EVLOCK_TRY_LOCK(void *lock)
245 {
246  if (lock) {
247  int r = _evthreadimpl_lock_lock(EVTHREAD_TRY, lock);
248  return !r;
249  } else {
250  /* Locking is disabled either globally or for this thing;
251  * of course we count as having the lock. */
252  return 1;
253  }
254 }
255 
256 /** Allocate a new condition variable and store it in the void *, condvar */
257 #define EVTHREAD_ALLOC_COND(condvar) \
258  do { \
259  (condvar) = _evthreadimpl_cond_alloc(0); \
260  } while (0)
261 /** Deallocate and free a condition variable in condvar */
262 #define EVTHREAD_FREE_COND(cond) \
263  do { \
264  if (cond) \
265  _evthreadimpl_cond_free((cond)); \
266  } while (0)
267 /** Signal one thread waiting on cond */
268 #define EVTHREAD_COND_SIGNAL(cond) \
269  ( (cond) ? _evthreadimpl_cond_signal((cond), 0) : 0 )
270 /** Signal all threads waiting on cond */
271 #define EVTHREAD_COND_BROADCAST(cond) \
272  ( (cond) ? _evthreadimpl_cond_signal((cond), 1) : 0 )
273 /** Wait until the condition 'cond' is signalled. Must be called while
274  * holding 'lock'. The lock will be released until the condition is
275  * signalled, at which point it will be acquired again. Returns 0 for
276  * success, -1 for failure. */
277 #define EVTHREAD_COND_WAIT(cond, lock) \
278  ( (cond) ? _evthreadimpl_cond_wait((cond), (lock), NULL) : 0 )
279 /** As EVTHREAD_COND_WAIT, but gives up after 'tv' has elapsed. Returns 1
280  * on timeout. */
281 #define EVTHREAD_COND_WAIT_TIMED(cond, lock, tv) \
282  ( (cond) ? _evthreadimpl_cond_wait((cond), (lock), (tv)) : 0 )
283 
284 #else /* _EVENT_DISABLE_THREAD_SUPPORT */
285 
286 #define EVTHREAD_GET_ID() 1
287 #define EVTHREAD_ALLOC_LOCK(lockvar, locktype) _EVUTIL_NIL_STMT
288 #define EVTHREAD_FREE_LOCK(lockvar, locktype) _EVUTIL_NIL_STMT
289 
290 #define EVLOCK_LOCK(lockvar, mode) _EVUTIL_NIL_STMT
291 #define EVLOCK_UNLOCK(lockvar, mode) _EVUTIL_NIL_STMT
292 #define EVLOCK_LOCK2(lock1,lock2,mode1,mode2) _EVUTIL_NIL_STMT
293 #define EVLOCK_UNLOCK2(lock1,lock2,mode1,mode2) _EVUTIL_NIL_STMT
294 
295 #define EVBASE_IN_THREAD(base) 1
296 #define EVBASE_NEED_NOTIFY(base) 0
297 #define EVBASE_ACQUIRE_LOCK(base, lock) _EVUTIL_NIL_STMT
298 #define EVBASE_RELEASE_LOCK(base, lock) _EVUTIL_NIL_STMT
299 #define EVLOCK_ASSERT_LOCKED(lock) _EVUTIL_NIL_STMT
300 
301 #define EVLOCK_TRY_LOCK(lock) 1
302 
303 #define EVTHREAD_ALLOC_COND(condvar) _EVUTIL_NIL_STMT
304 #define EVTHREAD_FREE_COND(cond) _EVUTIL_NIL_STMT
305 #define EVTHREAD_COND_SIGNAL(cond) _EVUTIL_NIL_STMT
306 #define EVTHREAD_COND_BROADCAST(cond) _EVUTIL_NIL_STMT
307 #define EVTHREAD_COND_WAIT(cond, lock) _EVUTIL_NIL_STMT
308 #define EVTHREAD_COND_WAIT_TIMED(cond, lock, howlong) _EVUTIL_NIL_STMT
309 
310 #endif
311 
312 /* This code is shared between both lock impls */
313 #if ! defined(_EVENT_DISABLE_THREAD_SUPPORT)
314 /** Helper: put lockvar1 and lockvar2 into pointerwise ascending order. */
315 #define _EVLOCK_SORTLOCKS(lockvar1, lockvar2) \
316  do { \
317  if (lockvar1 && lockvar2 && lockvar1 > lockvar2) { \
318  void *tmp = lockvar1; \
319  lockvar1 = lockvar2; \
320  lockvar2 = tmp; \
321  } \
322  } while (0)
323 
324 /** Acquire both lock1 and lock2. Always allocates locks in the same order,
325  * so that two threads locking two locks with LOCK2 will not deadlock. */
326 #define EVLOCK_LOCK2(lock1,lock2,mode1,mode2) \
327  do { \
328  void *_lock1_tmplock = (lock1); \
329  void *_lock2_tmplock = (lock2); \
330  _EVLOCK_SORTLOCKS(_lock1_tmplock,_lock2_tmplock); \
331  EVLOCK_LOCK(_lock1_tmplock,mode1); \
332  if (_lock2_tmplock != _lock1_tmplock) \
333  EVLOCK_LOCK(_lock2_tmplock,mode2); \
334  } while (0)
335 /** Release both lock1 and lock2. */
336 #define EVLOCK_UNLOCK2(lock1,lock2,mode1,mode2) \
337  do { \
338  void *_lock1_tmplock = (lock1); \
339  void *_lock2_tmplock = (lock2); \
340  _EVLOCK_SORTLOCKS(_lock1_tmplock,_lock2_tmplock); \
341  if (_lock2_tmplock != _lock1_tmplock) \
342  EVLOCK_UNLOCK(_lock2_tmplock,mode2); \
343  EVLOCK_UNLOCK(_lock1_tmplock,mode1); \
344  } while (0)
345 
346 int _evthread_is_debug_lock_held(void *lock);
347 void *_evthread_debug_get_real_lock(void *lock);
348 
349 void *evthread_setup_global_lock_(void *lock_, unsigned locktype,
350  int enable_locks);
351 
352 #define EVTHREAD_SETUP_GLOBAL_LOCK(lockvar, locktype) \
353  do { \
354  lockvar = evthread_setup_global_lock_(lockvar, \
355  (locktype), enable_locks); \
356  if (!lockvar) { \
357  event_warn("Couldn't allocate %s", #lockvar); \
358  return -1; \
359  } \
360  } while (0);
361 
362 int event_global_setup_locks_(const int enable_locks);
363 int evsig_global_setup_locks_(const int enable_locks);
364 int evutil_secure_rng_global_setup_locks_(const int enable_locks);
365 
366 #endif
367 
368 #ifdef __cplusplus
369 }
370 #endif
371 
372 #endif /* _EVTHREAD_INTERNAL_H_ */
This structure describes the interface a threading library uses for condition variables.
Definition: thread.h:141
Functions for multi-threaded applications using Libevent.
int(* lock)(unsigned mode, void *lock)
Acquire an already-allocated lock at 'lock' with mode 'mode'.
Definition: thread.h:117
#define EVTHREAD_TRY
A flag passed to a locking callback when we don't want to block waiting for the lock; if we can't get...
Definition: thread.h:73
This structure describes the interface a threading library uses for locking.
Definition: thread.h:97
Definition: event-internal.h:167