1 ///////////////////////////////////////////////////////////////////////////////
4 /// \brief Some threading related helper macros and functions
6 // Author: Lasse Collin
8 // This file has been put into the public domain.
9 // You can do whatever you want with this file.
11 ///////////////////////////////////////////////////////////////////////////////
18 // If any type of threading is enabled, #define MYTHREAD_ENABLED.
19 #if defined(MYTHREAD_POSIX) || defined(MYTHREAD_WIN95) \
20 || defined(MYTHREAD_VISTA)
21 # define MYTHREAD_ENABLED 1
25 #ifdef MYTHREAD_ENABLED
27 ////////////////////////////////////////
28 // Shared between all threading types //
29 ////////////////////////////////////////
31 // Locks a mutex for a duration of a block.
33 // Perform mythread_mutex_lock(&mutex) in the beginning of a block
34 // and mythread_mutex_unlock(&mutex) at the end of the block. "break"
35 // may be used to unlock the mutex and jump out of the block.
36 // mythread_sync blocks may be nested.
40 // mythread_sync(mutex) {
43 // break; // Skips bar()
47 // At least GCC optimizes the loops completely away so it doesn't slow
48 // things down at all compared to plain mythread_mutex_lock(&mutex)
49 // and mythread_mutex_unlock(&mutex) calls.
51 #define mythread_sync(mutex) mythread_sync_helper1(mutex, __LINE__)
52 #define mythread_sync_helper1(mutex, line) mythread_sync_helper2(mutex, line)
53 #define mythread_sync_helper2(mutex, line) \
54 for (unsigned int mythread_i_ ## line = 0; \
56 ? (mythread_mutex_unlock(&(mutex)), 0) \
57 : (mythread_mutex_lock(&(mutex)), 1); \
58 mythread_i_ ## line = 1) \
59 for (unsigned int mythread_j_ ## line = 0; \
60 !mythread_j_ ## line; \
61 mythread_j_ ## line = 1)
65 #if !defined(MYTHREAD_ENABLED)
71 // Calls the given function once. This isn't thread safe.
72 #define mythread_once(func) \
74 static bool once_ = false; \
82 #if !(defined(_WIN32) && !defined(__CYGWIN__))
83 // Use sigprocmask() to set the signal mask in single-threaded programs.
87 mythread_sigmask(int how, const sigset_t *restrict set,
88 sigset_t *restrict oset)
90 int ret = sigprocmask(how, set, oset);
97 #elif defined(MYTHREAD_POSIX)
103 #include <sys/time.h>
109 #define MYTHREAD_RET_TYPE void *
110 #define MYTHREAD_RET_VALUE NULL
112 typedef pthread_t mythread;
113 typedef pthread_mutex_t mythread_mutex;
117 #ifdef HAVE_CLOCK_GETTIME
118 // Clock ID (CLOCK_REALTIME or CLOCK_MONOTONIC) associated with
119 // the condition variable.
124 typedef struct timespec mythread_condtime;
127 // Calls the given function once in a thread-safe way.
128 #define mythread_once(func) \
130 static pthread_once_t once_ = PTHREAD_ONCE_INIT; \
131 pthread_once(&once_, &func); \
135 // Use pthread_sigmask() to set the signal mask in multi-threaded programs.
136 // Do nothing on OpenVMS since it lacks pthread_sigmask().
138 mythread_sigmask(int how, const sigset_t *restrict set,
139 sigset_t *restrict oset)
146 int ret = pthread_sigmask(how, set, oset);
153 // Creates a new thread with all signals blocked. Returns zero on success
154 // and non-zero on error.
156 mythread_create(mythread *thread, void *(*func)(void *arg), void *arg)
162 mythread_sigmask(SIG_SETMASK, &all, &old);
163 const int ret = pthread_create(thread, NULL, func, arg);
164 mythread_sigmask(SIG_SETMASK, &old, NULL);
169 // Joins a thread. Returns zero on success and non-zero on error.
171 mythread_join(mythread thread)
173 return pthread_join(thread, NULL);
177 // Initiatlizes a mutex. Returns zero on success and non-zero on error.
179 mythread_mutex_init(mythread_mutex *mutex)
181 return pthread_mutex_init(mutex, NULL);
185 mythread_mutex_destroy(mythread_mutex *mutex)
187 int ret = pthread_mutex_destroy(mutex);
193 mythread_mutex_lock(mythread_mutex *mutex)
195 int ret = pthread_mutex_lock(mutex);
201 mythread_mutex_unlock(mythread_mutex *mutex)
203 int ret = pthread_mutex_unlock(mutex);
209 // Initializes a condition variable.
211 // Using CLOCK_MONOTONIC instead of the default CLOCK_REALTIME makes the
212 // timeout in pthread_cond_timedwait() work correctly also if system time
213 // is suddenly changed. Unfortunately CLOCK_MONOTONIC isn't available
214 // everywhere while the default CLOCK_REALTIME is, so the default is
215 // used if CLOCK_MONOTONIC isn't available.
217 // If clock_gettime() isn't available at all, gettimeofday() will be used.
219 mythread_cond_init(mythread_cond *mycond)
221 #ifdef HAVE_CLOCK_GETTIME
222 // NOTE: HAVE_DECL_CLOCK_MONOTONIC is always defined to 0 or 1.
223 # if defined(HAVE_PTHREAD_CONDATTR_SETCLOCK) && HAVE_DECL_CLOCK_MONOTONIC
225 pthread_condattr_t condattr;
227 // POSIX doesn't seem to *require* that pthread_condattr_setclock()
228 // will fail if given an unsupported clock ID. Test that
229 // CLOCK_MONOTONIC really is supported using clock_gettime().
230 if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0
231 && pthread_condattr_init(&condattr) == 0) {
232 int ret = pthread_condattr_setclock(
233 &condattr, CLOCK_MONOTONIC);
235 ret = pthread_cond_init(&mycond->cond, &condattr);
237 pthread_condattr_destroy(&condattr);
240 mycond->clk_id = CLOCK_MONOTONIC;
245 // If anything above fails, fall back to the default CLOCK_REALTIME.
246 // POSIX requires that all implementations of clock_gettime() must
247 // support at least CLOCK_REALTIME.
250 mycond->clk_id = CLOCK_REALTIME;
253 return pthread_cond_init(&mycond->cond, NULL);
257 mythread_cond_destroy(mythread_cond *cond)
259 int ret = pthread_cond_destroy(&cond->cond);
265 mythread_cond_signal(mythread_cond *cond)
267 int ret = pthread_cond_signal(&cond->cond);
273 mythread_cond_wait(mythread_cond *cond, mythread_mutex *mutex)
275 int ret = pthread_cond_wait(&cond->cond, mutex);
280 // Waits on a condition or until a timeout expires. If the timeout expires,
281 // non-zero is returned, otherwise zero is returned.
283 mythread_cond_timedwait(mythread_cond *cond, mythread_mutex *mutex,
284 const mythread_condtime *condtime)
286 int ret = pthread_cond_timedwait(&cond->cond, mutex, condtime);
287 assert(ret == 0 || ret == ETIMEDOUT);
291 // Sets condtime to the absolute time that is timeout_ms milliseconds
292 // in the future. The type of the clock to use is taken from cond.
294 mythread_condtime_set(mythread_condtime *condtime, const mythread_cond *cond,
297 condtime->tv_sec = timeout_ms / 1000;
298 condtime->tv_nsec = (timeout_ms % 1000) * 1000000;
300 #ifdef HAVE_CLOCK_GETTIME
302 int ret = clock_gettime(cond->clk_id, &now);
306 condtime->tv_sec += now.tv_sec;
307 condtime->tv_nsec += now.tv_nsec;
312 gettimeofday(&now, NULL);
314 condtime->tv_sec += now.tv_sec;
315 condtime->tv_nsec += now.tv_usec * 1000L;
318 // tv_nsec must stay in the range [0, 999_999_999].
319 if (condtime->tv_nsec >= 1000000000L) {
320 condtime->tv_nsec -= 1000000000L;
326 #elif defined(MYTHREAD_WIN95) || defined(MYTHREAD_VISTA)
328 /////////////////////
329 // Windows threads //
330 /////////////////////
332 #define WIN32_LEAN_AND_MEAN
333 #ifdef MYTHREAD_VISTA
335 # define _WIN32_WINNT 0x0600
340 #define MYTHREAD_RET_TYPE unsigned int __stdcall
341 #define MYTHREAD_RET_VALUE 0
343 typedef HANDLE mythread;
344 typedef CRITICAL_SECTION mythread_mutex;
346 #ifdef MYTHREAD_WIN95
347 typedef HANDLE mythread_cond;
349 typedef CONDITION_VARIABLE mythread_cond;
353 // Tick count (milliseconds) in the beginning of the timeout.
354 // NOTE: This is 32 bits so it wraps around after 49.7 days.
355 // Multi-day timeouts may not work as expected.
358 // Length of the timeout in milliseconds. The timeout expires
359 // when the current tick count minus "start" is equal or greater
365 // mythread_once() is only available with Vista threads.
366 #ifdef MYTHREAD_VISTA
367 #define mythread_once(func) \
369 static INIT_ONCE once_ = INIT_ONCE_STATIC_INIT; \
371 if (!InitOnceBeginInitialize(&once_, 0, &pending_, NULL)) \
375 if (!InitOnceComplete(&once, 0, NULL)) \
381 // mythread_sigmask() isn't available on Windows. Even a dummy version would
382 // make no sense because the other POSIX signal functions are missing anyway.
386 mythread_create(mythread *thread,
387 unsigned int (__stdcall *func)(void *arg), void *arg)
389 uintptr_t ret = _beginthreadex(NULL, 0, func, arg, 0, NULL);
393 *thread = (HANDLE)ret;
398 mythread_join(mythread thread)
402 if (WaitForSingleObject(thread, INFINITE) != WAIT_OBJECT_0)
405 if (!CloseHandle(thread))
413 mythread_mutex_init(mythread_mutex *mutex)
415 InitializeCriticalSection(mutex);
420 mythread_mutex_destroy(mythread_mutex *mutex)
422 DeleteCriticalSection(mutex);
426 mythread_mutex_lock(mythread_mutex *mutex)
428 EnterCriticalSection(mutex);
432 mythread_mutex_unlock(mythread_mutex *mutex)
434 LeaveCriticalSection(mutex);
439 mythread_cond_init(mythread_cond *cond)
441 #ifdef MYTHREAD_WIN95
442 *cond = CreateEvent(NULL, FALSE, FALSE, NULL);
443 return *cond == NULL ? -1 : 0;
445 InitializeConditionVariable(cond);
451 mythread_cond_destroy(mythread_cond *cond)
453 #ifdef MYTHREAD_WIN95
461 mythread_cond_signal(mythread_cond *cond)
463 #ifdef MYTHREAD_WIN95
466 WakeConditionVariable(cond);
471 mythread_cond_wait(mythread_cond *cond, mythread_mutex *mutex)
473 #ifdef MYTHREAD_WIN95
474 LeaveCriticalSection(mutex);
475 WaitForSingleObject(*cond, INFINITE);
476 EnterCriticalSection(mutex);
478 BOOL ret = SleepConditionVariableCS(cond, mutex, INFINITE);
485 mythread_cond_timedwait(mythread_cond *cond, mythread_mutex *mutex,
486 const mythread_condtime *condtime)
488 #ifdef MYTHREAD_WIN95
489 LeaveCriticalSection(mutex);
492 DWORD elapsed = GetTickCount() - condtime->start;
493 DWORD timeout = elapsed >= condtime->timeout
494 ? 0 : condtime->timeout - elapsed;
496 #ifdef MYTHREAD_WIN95
497 DWORD ret = WaitForSingleObject(*cond, timeout);
498 assert(ret == WAIT_OBJECT_0 || ret == WAIT_TIMEOUT);
500 EnterCriticalSection(mutex);
502 return ret == WAIT_TIMEOUT;
504 BOOL ret = SleepConditionVariableCS(cond, mutex, timeout);
505 assert(ret || GetLastError() == ERROR_TIMEOUT);
511 mythread_condtime_set(mythread_condtime *condtime, const mythread_cond *cond,
515 condtime->start = GetTickCount();
516 condtime->timeout = timeout;