evthread-internal.h

   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_INCLUDED_
  27 #define EVTHREAD_INTERNAL_H_INCLUDED_
  28
  29 #ifdef __cplusplus
  30 extern "C" {
  31 #endif
  32
  33 #include "event2/event-config.h"
  34 #include "evconfig-private.h"
  35
  36 #include "event2/thread.h"
  37 #include "util-internal.h"
  38
  39 struct event_base;
  40
  41 #ifndef _WIN32
  42 /* On Windows, the way we currently make DLLs, it's not allowed for us to
  43  * have shared global structures.  Thus, we only do the direct-call-to-function
  44  * code path if we know that the local shared library system supports it.
  45  */
  46 #define EVTHREAD_EXPOSE_STRUCTS
  47 #endif
  48
  49 #if ! defined(EVENT__DISABLE_THREAD_SUPPORT) && defined(EVTHREAD_EXPOSE_STRUCTS)
  50 /* Global function pointers to lock-related functions. NULL if locking isn't
  51    enabled. */
  52 extern struct evthread_lock_callbacks evthread_lock_fns_;
  53 extern struct evthread_condition_callbacks evthread_cond_fns_;
  54 extern unsigned long (*evthread_id_fn_)(void);
  55 extern int evthread_lock_debugging_enabled_;
  56
  57 /** Return the ID of the current thread, or 1 if threading isn't enabled. */
  58 #define EVTHREAD_GET_ID() \
  59         (evthread_id_fn_ ? evthread_id_fn_() : 1)
  60
  61 /** Return true iff we're in the thread that is currently (or most recently)
  62  * running a given event_base's loop. Requires lock. */
  63 #define EVBASE_IN_THREAD(base)                           \
  64         (evthread_id_fn_ == NULL ||                      \
  65         (base)->th_owner_id == evthread_id_fn_())
  66
  67 /** Return true iff we need to notify the base's main thread about changes to
  68  * its state, because it's currently running the main loop in another
  69  * thread. Requires lock. */
  70 #define EVBASE_NEED_NOTIFY(base)                         \
  71         (evthread_id_fn_ != NULL &&                      \
  72             (base)->running_loop &&                      \
  73             (base)->th_owner_id != evthread_id_fn_())
  74
  75 /** Allocate a new lock, and store it in lockvar, a void*.  Sets lockvar to
  76     NULL if locking is not enabled. */
  77 #define EVTHREAD_ALLOC_LOCK(lockvar, locktype)          \
  78         ((lockvar) = evthread_lock_fns_.alloc ?         \
  79             evthread_lock_fns_.alloc(locktype) : NULL)
  80
  81 /** Free a given lock, if it is present and locking is enabled. */
  82 #define EVTHREAD_FREE_LOCK(lockvar, locktype)                           \
  83         do {                                                            \
  84                 void *lock_tmp_ = (lockvar);                            \
  85                 if (lock_tmp_ && evthread_lock_fns_.free)               \
  86                         evthread_lock_fns_.free(lock_tmp_, (locktype)); \
  87         } while (0)
  88
  89 /** Acquire a lock. */
  90 #define EVLOCK_LOCK(lockvar,mode)                                       \
  91         do {                                                            \
  92                 if (lockvar)                                            \
  93                         evthread_lock_fns_.lock(mode, lockvar);         \
  94         } while (0)
  95
  96 /** Release a lock */
  97 #define EVLOCK_UNLOCK(lockvar,mode)                                     \
  98         do {                                                            \
  99                 if (lockvar)                                            \
 100                         evthread_lock_fns_.unlock(mode, lockvar);       \
 101         } while (0)
 102
 103 /** Helper: put lockvar1 and lockvar2 into pointerwise ascending order. */
 104 #define EVLOCK_SORTLOCKS_(lockvar1, lockvar2)                           \
 105         do {                                                            \
 106                 if (lockvar1 && lockvar2 && lockvar1 > lockvar2) {      \
 107                         void *tmp = lockvar1;                           \
 108                         lockvar1 = lockvar2;                            \
 109                         lockvar2 = tmp;                                 \
 110                 }                                                       \
 111         } while (0)
 112
 113 /** Lock an event_base, if it is set up for locking.  Acquires the lock
 114     in the base structure whose field is named 'lockvar'. */
 115 #define EVBASE_ACQUIRE_LOCK(base, lockvar) do {                         \
 116                 EVLOCK_LOCK((base)->lockvar, 0);                        \
 117         } while (0)
 118
 119 /** Unlock an event_base, if it is set up for locking. */
 120 #define EVBASE_RELEASE_LOCK(base, lockvar) do {                         \
 121                 EVLOCK_UNLOCK((base)->lockvar, 0);                      \
 122         } while (0)
 123
 124 /** If lock debugging is enabled, and lock is non-null, assert that 'lock' is
 125  * locked and held by us. */
 126 #define EVLOCK_ASSERT_LOCKED(lock)                                      \
 127         do {                                                            \
 128                 if ((lock) && evthread_lock_debugging_enabled_) {       \
 129                         EVUTIL_ASSERT(evthread_is_debug_lock_held_(lock)); \
 130                 }                                                       \
 131         } while (0)
 132
 133 /** Try to grab the lock for 'lockvar' without blocking, and return 1 if we
 134  * manage to get it. */
 135 static inline int EVLOCK_TRY_LOCK_(void *lock);
 136 static inline int
 137 EVLOCK_TRY_LOCK_(void *lock)
 138 {
 139         if (lock && evthread_lock_fns_.lock) {
 140                 int r = evthread_lock_fns_.lock(EVTHREAD_TRY, lock);
 141                 return !r;
 142         } else {
 143                 /* Locking is disabled either globally or for this thing;
 144                  * of course we count as having the lock. */
 145                 return 1;
 146         }
 147 }
 148
 149 /** Allocate a new condition variable and store it in the void *, condvar */
 150 #define EVTHREAD_ALLOC_COND(condvar)                                    \
 151         do {                                                            \
 152                 (condvar) = evthread_cond_fns_.alloc_condition ?        \
 153                     evthread_cond_fns_.alloc_condition(0) : NULL;       \
 154         } while (0)
 155 /** Deallocate and free a condition variable in condvar */
 156 #define EVTHREAD_FREE_COND(cond)                                        \
 157         do {                                                            \
 158                 if (cond)                                               \
 159                         evthread_cond_fns_.free_condition((cond));      \
 160         } while (0)
 161 /** Signal one thread waiting on cond */
 162 #define EVTHREAD_COND_SIGNAL(cond)                                      \
 163         ( (cond) ? evthread_cond_fns_.signal_condition((cond), 0) : 0 )
 164 /** Signal all threads waiting on cond */
 165 #define EVTHREAD_COND_BROADCAST(cond)                                   \
 166         ( (cond) ? evthread_cond_fns_.signal_condition((cond), 1) : 0 )
 167 /** Wait until the condition 'cond' is signalled.  Must be called while
 168  * holding 'lock'.  The lock will be released until the condition is
 169  * signalled, at which point it will be acquired again.  Returns 0 for
 170  * success, -1 for failure. */
 171 #define EVTHREAD_COND_WAIT(cond, lock)                                  \
 172         ( (cond) ? evthread_cond_fns_.wait_condition((cond), (lock), NULL) : 0 )
 173 /** As EVTHREAD_COND_WAIT, but gives up after 'tv' has elapsed.  Returns 1
 174  * on timeout. */
 175 #define EVTHREAD_COND_WAIT_TIMED(cond, lock, tv)                        \
 176         ( (cond) ? evthread_cond_fns_.wait_condition((cond), (lock), (tv)) : 0 )
 177
 178 /** True iff locking functions have been configured. */
 179 #define EVTHREAD_LOCKING_ENABLED()              \
 180         (evthread_lock_fns_.lock != NULL)
 181
 182 #elif ! defined(EVENT__DISABLE_THREAD_SUPPORT)
 183
 184 unsigned long evthreadimpl_get_id_(void);
 185 int evthreadimpl_is_lock_debugging_enabled_(void);
 186 void *evthreadimpl_lock_alloc_(unsigned locktype);
 187 void evthreadimpl_lock_free_(void *lock, unsigned locktype);
 188 int evthreadimpl_lock_lock_(unsigned mode, void *lock);
 189 int evthreadimpl_lock_unlock_(unsigned mode, void *lock);
 190 void *evthreadimpl_cond_alloc_(unsigned condtype);
 191 void evthreadimpl_cond_free_(void *cond);
 192 int evthreadimpl_cond_signal_(void *cond, int broadcast);
 193 int evthreadimpl_cond_wait_(void *cond, void *lock, const struct timeval *tv);
 194 int evthreadimpl_locking_enabled_(void);
 195
 196 #define EVTHREAD_GET_ID() evthreadimpl_get_id_()
 197 #define EVBASE_IN_THREAD(base)                          \
 198         ((base)->th_owner_id == evthreadimpl_get_id_())
 199 #define EVBASE_NEED_NOTIFY(base)                         \
 200         ((base)->running_loop &&                         \
 201             ((base)->th_owner_id != evthreadimpl_get_id_()))
 202
 203 #define EVTHREAD_ALLOC_LOCK(lockvar, locktype)          \
 204         ((lockvar) = evthreadimpl_lock_alloc_(locktype))
 205
 206 #define EVTHREAD_FREE_LOCK(lockvar, locktype)                           \
 207         do {                                                            \
 208                 void *lock_tmp_ = (lockvar);                            \
 209                 if (lock_tmp_)                                          \
 210                         evthreadimpl_lock_free_(lock_tmp_, (locktype)); \
 211         } while (0)
 212
 213 /** Acquire a lock. */
 214 #define EVLOCK_LOCK(lockvar,mode)                                       \
 215         do {                                                            \
 216                 if (lockvar)                                            \
 217                         evthreadimpl_lock_lock_(mode, lockvar);         \
 218         } while (0)
 219
 220 /** Release a lock */
 221 #define EVLOCK_UNLOCK(lockvar,mode)                                     \
 222         do {                                                            \
 223                 if (lockvar)                                            \
 224                         evthreadimpl_lock_unlock_(mode, lockvar);       \
 225         } while (0)
 226
 227 /** Lock an event_base, if it is set up for locking.  Acquires the lock
 228     in the base structure whose field is named 'lockvar'. */
 229 #define EVBASE_ACQUIRE_LOCK(base, lockvar) do {                         \
 230                 EVLOCK_LOCK((base)->lockvar, 0);                        \
 231         } while (0)
 232
 233 /** Unlock an event_base, if it is set up for locking. */
 234 #define EVBASE_RELEASE_LOCK(base, lockvar) do {                         \
 235                 EVLOCK_UNLOCK((base)->lockvar, 0);                      \
 236         } while (0)
 237
 238 /** If lock debugging is enabled, and lock is non-null, assert that 'lock' is
 239  * locked and held by us. */
 240 #define EVLOCK_ASSERT_LOCKED(lock)                                      \
 241         do {                                                            \
 242                 if ((lock) && evthreadimpl_is_lock_debugging_enabled_()) { \
 243                         EVUTIL_ASSERT(evthread_is_debug_lock_held_(lock)); \
 244                 }                                                       \
 245         } while (0)
 246
 247 /** Try to grab the lock for 'lockvar' without blocking, and return 1 if we
 248  * manage to get it. */
 249 static inline int EVLOCK_TRY_LOCK_(void *lock);
 250 static inline int
 251 EVLOCK_TRY_LOCK_(void *lock)
 252 {
 253         if (lock) {
 254                 int r = evthreadimpl_lock_lock_(EVTHREAD_TRY, lock);
 255                 return !r;
 256         } else {
 257                 /* Locking is disabled either globally or for this thing;
 258                  * of course we count as having the lock. */
 259                 return 1;
 260         }
 261 }
 262
 263 /** Allocate a new condition variable and store it in the void *, condvar */
 264 #define EVTHREAD_ALLOC_COND(condvar)                                    \
 265         do {                                                            \
 266                 (condvar) = evthreadimpl_cond_alloc_(0);                \
 267         } while (0)
 268 /** Deallocate and free a condition variable in condvar */
 269 #define EVTHREAD_FREE_COND(cond)                                        \
 270         do {                                                            \
 271                 if (cond)                                               \
 272                         evthreadimpl_cond_free_((cond));                \
 273         } while (0)
 274 /** Signal one thread waiting on cond */
 275 #define EVTHREAD_COND_SIGNAL(cond)                                      \
 276         ( (cond) ? evthreadimpl_cond_signal_((cond), 0) : 0 )
 277 /** Signal all threads waiting on cond */
 278 #define EVTHREAD_COND_BROADCAST(cond)                                   \
 279         ( (cond) ? evthreadimpl_cond_signal_((cond), 1) : 0 )
 280 /** Wait until the condition 'cond' is signalled.  Must be called while
 281  * holding 'lock'.  The lock will be released until the condition is
 282  * signalled, at which point it will be acquired again.  Returns 0 for
 283  * success, -1 for failure. */
 284 #define EVTHREAD_COND_WAIT(cond, lock)                                  \
 285         ( (cond) ? evthreadimpl_cond_wait_((cond), (lock), NULL) : 0 )
 286 /** As EVTHREAD_COND_WAIT, but gives up after 'tv' has elapsed.  Returns 1
 287  * on timeout. */
 288 #define EVTHREAD_COND_WAIT_TIMED(cond, lock, tv)                        \
 289         ( (cond) ? evthreadimpl_cond_wait_((cond), (lock), (tv)) : 0 )
 290
 291 #define EVTHREAD_LOCKING_ENABLED()              \
 292         (evthreadimpl_locking_enabled_())
 293
 294 #else /* EVENT__DISABLE_THREAD_SUPPORT */
 295
 296 #define EVTHREAD_GET_ID()       1
 297 #define EVTHREAD_ALLOC_LOCK(lockvar, locktype) EVUTIL_NIL_STMT_
 298 #define EVTHREAD_FREE_LOCK(lockvar, locktype) EVUTIL_NIL_STMT_
 299
 300 #define EVLOCK_LOCK(lockvar, mode) EVUTIL_NIL_STMT_
 301 #define EVLOCK_UNLOCK(lockvar, mode) EVUTIL_NIL_STMT_
 302 #define EVLOCK_LOCK2(lock1,lock2,mode1,mode2) EVUTIL_NIL_STMT_
 303 #define EVLOCK_UNLOCK2(lock1,lock2,mode1,mode2) EVUTIL_NIL_STMT_
 304
 305 #define EVBASE_IN_THREAD(base)  1
 306 #define EVBASE_NEED_NOTIFY(base) 0
 307 #define EVBASE_ACQUIRE_LOCK(base, lock) EVUTIL_NIL_STMT_
 308 #define EVBASE_RELEASE_LOCK(base, lock) EVUTIL_NIL_STMT_
 309 #define EVLOCK_ASSERT_LOCKED(lock) EVUTIL_NIL_STMT_
 310
 311 #define EVLOCK_TRY_LOCK_(lock) 1
 312
 313 #define EVTHREAD_ALLOC_COND(condvar) EVUTIL_NIL_STMT_
 314 #define EVTHREAD_FREE_COND(cond) EVUTIL_NIL_STMT_
 315 #define EVTHREAD_COND_SIGNAL(cond) EVUTIL_NIL_STMT_
 316 #define EVTHREAD_COND_BROADCAST(cond) EVUTIL_NIL_STMT_
 317 #define EVTHREAD_COND_WAIT(cond, lock) EVUTIL_NIL_STMT_
 318 #define EVTHREAD_COND_WAIT_TIMED(cond, lock, howlong) EVUTIL_NIL_STMT_
 319
 320 #define EVTHREAD_LOCKING_ENABLED() 0
 321
 322 #endif
 323
 324 /* This code is shared between both lock impls */
 325 #if ! defined(EVENT__DISABLE_THREAD_SUPPORT)
 326 /** Helper: put lockvar1 and lockvar2 into pointerwise ascending order. */
 327 #define EVLOCK_SORTLOCKS_(lockvar1, lockvar2)                           \
 328         do {                                                            \
 329                 if (lockvar1 && lockvar2 && lockvar1 > lockvar2) {      \
 330                         void *tmp = lockvar1;                           \
 331                         lockvar1 = lockvar2;                            \
 332                         lockvar2 = tmp;                                 \
 333                 }                                                       \
 334         } while (0)
 335
 336 /** Acquire both lock1 and lock2.  Always allocates locks in the same order,
 337  * so that two threads locking two locks with LOCK2 will not deadlock. */
 338 #define EVLOCK_LOCK2(lock1,lock2,mode1,mode2)                           \
 339         do {                                                            \
 340                 void *lock1_tmplock_ = (lock1);                         \
 341                 void *lock2_tmplock_ = (lock2);                         \
 342                 EVLOCK_SORTLOCKS_(lock1_tmplock_,lock2_tmplock_);       \
 343                 EVLOCK_LOCK(lock1_tmplock_,mode1);                      \
 344                 if (lock2_tmplock_ != lock1_tmplock_)                   \
 345                         EVLOCK_LOCK(lock2_tmplock_,mode2);              \
 346         } while (0)
 347 /** Release both lock1 and lock2.  */
 348 #define EVLOCK_UNLOCK2(lock1,lock2,mode1,mode2)                         \
 349         do {                                                            \
 350                 void *lock1_tmplock_ = (lock1);                         \
 351                 void *lock2_tmplock_ = (lock2);                         \
 352                 EVLOCK_SORTLOCKS_(lock1_tmplock_,lock2_tmplock_);       \
 353                 if (lock2_tmplock_ != lock1_tmplock_)                   \
 354                         EVLOCK_UNLOCK(lock2_tmplock_,mode2);            \
 355                 EVLOCK_UNLOCK(lock1_tmplock_,mode1);                    \
 356         } while (0)
 357
 358 int evthread_is_debug_lock_held_(void *lock);
 359 void *evthread_debug_get_real_lock_(void *lock);
 360
 361 void *evthread_setup_global_lock_(void *lock_, unsigned locktype,
 362     int enable_locks);
 363
 364 #define EVTHREAD_SETUP_GLOBAL_LOCK(lockvar, locktype)                   \
 365         do {                                                            \
 366                 lockvar = evthread_setup_global_lock_(lockvar,          \
 367                     (locktype), enable_locks);                          \
 368                 if (!lockvar) {                                         \
 369                         event_warn("Couldn't allocate %s", #lockvar);   \
 370                         return -1;                                      \
 371                 }                                                       \
 372         } while (0);
 373
 374 int event_global_setup_locks_(const int enable_locks);
 375 int evsig_global_setup_locks_(const int enable_locks);
 376 int evutil_global_setup_locks_(const int enable_locks);
 377 int evutil_secure_rng_global_setup_locks_(const int enable_locks);
 378
 379 /** Return current evthread_lock_callbacks */
 380 struct evthread_lock_callbacks *evthread_get_lock_callbacks(void);
 381 /** Return current evthread_condition_callbacks */
 382 struct evthread_condition_callbacks *evthread_get_condition_callbacks(void);
 383 /** Disable locking for internal usage (like global shutdown) */
 384 void evthreadimpl_disable_lock_debugging_(void);
 385
 386 #endif
 387
 388 #ifdef __cplusplus
 389 }
 390 #endif
 391
 392 #endif /* EVTHREAD_INTERNAL_H_INCLUDED_ */