libevent/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 #endif
 349
 350 #ifdef __cplusplus
 351 }
 352 #endif
 353
 354 #endif /* _EVTHREAD_INTERNAL_H_ */