source: python/trunk/Python/thread_pthread.h@ 281

Last change on this file since 281 was 2, checked in by Yuri Dario, 15 years ago

Initial import for vendor code.
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1
2/* Posix threads interface */
3
4#include <stdlib.h>
5#include <string.h>
6#if defined(__APPLE__) || defined(HAVE_PTHREAD_DESTRUCTOR)
7#define destructor xxdestructor
8#endif
9#include <pthread.h>
10#if defined(__APPLE__) || defined(HAVE_PTHREAD_DESTRUCTOR)
11#undef destructor
12#endif
13#include <signal.h>
14
15/* The POSIX spec requires that use of pthread_attr_setstacksize
16 be conditional on _POSIX_THREAD_ATTR_STACKSIZE being defined. */
17#ifdef _POSIX_THREAD_ATTR_STACKSIZE
18#ifndef THREAD_STACK_SIZE
19#define THREAD_STACK_SIZE 0 /* use default stack size */
20#endif
21/* for safety, ensure a viable minimum stacksize */
22#define THREAD_STACK_MIN 0x8000 /* 32kB */
23#else /* !_POSIX_THREAD_ATTR_STACKSIZE */
24#ifdef THREAD_STACK_SIZE
25#error "THREAD_STACK_SIZE defined but _POSIX_THREAD_ATTR_STACKSIZE undefined"
26#endif
27#endif
28
29/* The POSIX spec says that implementations supporting the sem_*
30 family of functions must indicate this by defining
31 _POSIX_SEMAPHORES. */
32#ifdef _POSIX_SEMAPHORES
33/* On FreeBSD 4.x, _POSIX_SEMAPHORES is defined empty, so
34 we need to add 0 to make it work there as well. */
35#if (_POSIX_SEMAPHORES+0) == -1
36#define HAVE_BROKEN_POSIX_SEMAPHORES
37#else
38#include <semaphore.h>
39#include <errno.h>
40#endif
41#endif
42
43/* Before FreeBSD 5.4, system scope threads was very limited resource
44 in default setting. So the process scope is preferred to get
45 enough number of threads to work. */
46#ifdef __FreeBSD__
47#include <osreldate.h>
48#if __FreeBSD_version >= 500000 && __FreeBSD_version < 504101
49#undef PTHREAD_SYSTEM_SCHED_SUPPORTED
50#endif
51#endif
52
53#if !defined(pthread_attr_default)
54# define pthread_attr_default ((pthread_attr_t *)NULL)
55#endif
56#if !defined(pthread_mutexattr_default)
57# define pthread_mutexattr_default ((pthread_mutexattr_t *)NULL)
58#endif
59#if !defined(pthread_condattr_default)
60# define pthread_condattr_default ((pthread_condattr_t *)NULL)
61#endif
62
63
64/* Whether or not to use semaphores directly rather than emulating them with
65 * mutexes and condition variables:
66 */
67#if defined(_POSIX_SEMAPHORES) && !defined(HAVE_BROKEN_POSIX_SEMAPHORES)
68# define USE_SEMAPHORES
69#else
70# undef USE_SEMAPHORES
71#endif
72
73
74/* On platforms that don't use standard POSIX threads pthread_sigmask()
75 * isn't present. DEC threads uses sigprocmask() instead as do most
76 * other UNIX International compliant systems that don't have the full
77 * pthread implementation.
78 */
79#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK)
80# define SET_THREAD_SIGMASK pthread_sigmask
81#else
82# define SET_THREAD_SIGMASK sigprocmask
83#endif
84
85
86/* A pthread mutex isn't sufficient to model the Python lock type
87 * because, according to Draft 5 of the docs (P1003.4a/D5), both of the
88 * following are undefined:
89 * -> a thread tries to lock a mutex it already has locked
90 * -> a thread tries to unlock a mutex locked by a different thread
91 * pthread mutexes are designed for serializing threads over short pieces
92 * of code anyway, so wouldn't be an appropriate implementation of
93 * Python's locks regardless.
94 *
95 * The pthread_lock struct implements a Python lock as a "locked?" bit
96 * and a <condition, mutex> pair. In general, if the bit can be acquired
97 * instantly, it is, else the pair is used to block the thread until the
98 * bit is cleared. 9 May 1994 tim@ksr.com
99 */
100
101typedef struct {
102 char locked; /* 0=unlocked, 1=locked */
103 /* a <cond, mutex> pair to handle an acquire of a locked lock */
104 pthread_cond_t lock_released;
105 pthread_mutex_t mut;
106} pthread_lock;
107
108#define CHECK_STATUS(name) if (status != 0) { perror(name); error = 1; }
109
110/*
111 * Initialization.
112 */
113
114#ifdef _HAVE_BSDI
115static
116void _noop(void)
117{
118}
119
120static void
121PyThread__init_thread(void)
122{
123 /* DO AN INIT BY STARTING THE THREAD */
124 static int dummy = 0;
125 pthread_t thread1;
126 pthread_create(&thread1, NULL, (void *) _noop, &dummy);
127 pthread_join(thread1, NULL);
128}
129
130#else /* !_HAVE_BSDI */
131
132static void
133PyThread__init_thread(void)
134{
135#if defined(_AIX) && defined(__GNUC__)
136 pthread_init();
137#endif
138}
139
140#endif /* !_HAVE_BSDI */
141
142/*
143 * Thread support.
144 */
145
146
147long
148PyThread_start_new_thread(void (*func)(void *), void *arg)
149{
150 pthread_t th;
151 int status;
152#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
153 pthread_attr_t attrs;
154#endif
155#if defined(THREAD_STACK_SIZE)
156 size_t tss;
157#endif
158
159 dprintf(("PyThread_start_new_thread called\n"));
160 if (!initialized)
161 PyThread_init_thread();
162
163#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
164 if (pthread_attr_init(&attrs) != 0)
165 return -1;
166#endif
167#if defined(THREAD_STACK_SIZE)
168 tss = (_pythread_stacksize != 0) ? _pythread_stacksize
169 : THREAD_STACK_SIZE;
170 if (tss != 0) {
171 if (pthread_attr_setstacksize(&attrs, tss) != 0) {
172 pthread_attr_destroy(&attrs);
173 return -1;
174 }
175 }
176#endif
177#if defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
178 pthread_attr_setscope(&attrs, PTHREAD_SCOPE_SYSTEM);
179#endif
180
181 status = pthread_create(&th,
182#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
183 &attrs,
184#else
185 (pthread_attr_t*)NULL,
186#endif
187 (void* (*)(void *))func,
188 (void *)arg
189 );
190
191#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
192 pthread_attr_destroy(&attrs);
193#endif
194 if (status != 0)
195 return -1;
196
197 pthread_detach(th);
198
199#if SIZEOF_PTHREAD_T <= SIZEOF_LONG
200 return (long) th;
201#else
202 return (long) *(long *) &th;
203#endif
204}
205
206/* XXX This implementation is considered (to quote Tim Peters) "inherently
207 hosed" because:
208 - It does not guarantee the promise that a non-zero integer is returned.
209 - The cast to long is inherently unsafe.
210 - It is not clear that the 'volatile' (for AIX?) and ugly casting in the
211 latter return statement (for Alpha OSF/1) are any longer necessary.
212*/
213long
214PyThread_get_thread_ident(void)
215{
216 volatile pthread_t threadid;
217 if (!initialized)
218 PyThread_init_thread();
219 /* Jump through some hoops for Alpha OSF/1 */
220 threadid = pthread_self();
221#if SIZEOF_PTHREAD_T <= SIZEOF_LONG
222 return (long) threadid;
223#else
224 return (long) *(long *) &threadid;
225#endif
226}
227
228static void
229do_PyThread_exit_thread(int no_cleanup)
230{
231 dprintf(("PyThread_exit_thread called\n"));
232 if (!initialized) {
233 if (no_cleanup)
234 _exit(0);
235 else
236 exit(0);
237 }
238}
239
240void
241PyThread_exit_thread(void)
242{
243 do_PyThread_exit_thread(0);
244}
245
246void
247PyThread__exit_thread(void)
248{
249 do_PyThread_exit_thread(1);
250}
251
252#ifndef NO_EXIT_PROG
253static void
254do_PyThread_exit_prog(int status, int no_cleanup)
255{
256 dprintf(("PyThread_exit_prog(%d) called\n", status));
257 if (!initialized)
258 if (no_cleanup)
259 _exit(status);
260 else
261 exit(status);
262}
263
264void
265PyThread_exit_prog(int status)
266{
267 do_PyThread_exit_prog(status, 0);
268}
269
270void
271PyThread__exit_prog(int status)
272{
273 do_PyThread_exit_prog(status, 1);
274}
275#endif /* NO_EXIT_PROG */
276
277#ifdef USE_SEMAPHORES
278
279/*
280 * Lock support.
281 */
282
283PyThread_type_lock
284PyThread_allocate_lock(void)
285{
286 sem_t *lock;
287 int status, error = 0;
288
289 dprintf(("PyThread_allocate_lock called\n"));
290 if (!initialized)
291 PyThread_init_thread();
292
293 lock = (sem_t *)malloc(sizeof(sem_t));
294
295 if (lock) {
296 status = sem_init(lock,0,1);
297 CHECK_STATUS("sem_init");
298
299 if (error) {
300 free((void *)lock);
301 lock = NULL;
302 }
303 }
304
305 dprintf(("PyThread_allocate_lock() -> %p\n", lock));
306 return (PyThread_type_lock)lock;
307}
308
309void
310PyThread_free_lock(PyThread_type_lock lock)
311{
312 sem_t *thelock = (sem_t *)lock;
313 int status, error = 0;
314
315 dprintf(("PyThread_free_lock(%p) called\n", lock));
316
317 if (!thelock)
318 return;
319
320 status = sem_destroy(thelock);
321 CHECK_STATUS("sem_destroy");
322
323 free((void *)thelock);
324}
325
326/*
327 * As of February 2002, Cygwin thread implementations mistakenly report error
328 * codes in the return value of the sem_ calls (like the pthread_ functions).
329 * Correct implementations return -1 and put the code in errno. This supports
330 * either.
331 */
332static int
333fix_status(int status)
334{
335 return (status == -1) ? errno : status;
336}
337
338int
339PyThread_acquire_lock(PyThread_type_lock lock, int waitflag)
340{
341 int success;
342 sem_t *thelock = (sem_t *)lock;
343 int status, error = 0;
344
345 dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag));
346
347 do {
348 if (waitflag)
349 status = fix_status(sem_wait(thelock));
350 else
351 status = fix_status(sem_trywait(thelock));
352 } while (status == EINTR); /* Retry if interrupted by a signal */
353
354 if (waitflag) {
355 CHECK_STATUS("sem_wait");
356 } else if (status != EAGAIN) {
357 CHECK_STATUS("sem_trywait");
358 }
359
360 success = (status == 0) ? 1 : 0;
361
362 dprintf(("PyThread_acquire_lock(%p, %d) -> %d\n", lock, waitflag, success));
363 return success;
364}
365
366void
367PyThread_release_lock(PyThread_type_lock lock)
368{
369 sem_t *thelock = (sem_t *)lock;
370 int status, error = 0;
371
372 dprintf(("PyThread_release_lock(%p) called\n", lock));
373
374 status = sem_post(thelock);
375 CHECK_STATUS("sem_post");
376}
377
378#else /* USE_SEMAPHORES */
379
380/*
381 * Lock support.
382 */
383PyThread_type_lock
384PyThread_allocate_lock(void)
385{
386 pthread_lock *lock;
387 int status, error = 0;
388
389 dprintf(("PyThread_allocate_lock called\n"));
390 if (!initialized)
391 PyThread_init_thread();
392
393 lock = (pthread_lock *) malloc(sizeof(pthread_lock));
394 if (lock) {
395 memset((void *)lock, '\0', sizeof(pthread_lock));
396 lock->locked = 0;
397
398 status = pthread_mutex_init(&lock->mut,
399 pthread_mutexattr_default);
400 CHECK_STATUS("pthread_mutex_init");
401
402 status = pthread_cond_init(&lock->lock_released,
403 pthread_condattr_default);
404 CHECK_STATUS("pthread_cond_init");
405
406 if (error) {
407 free((void *)lock);
408 lock = 0;
409 }
410 }
411
412 dprintf(("PyThread_allocate_lock() -> %p\n", lock));
413 return (PyThread_type_lock) lock;
414}
415
416void
417PyThread_free_lock(PyThread_type_lock lock)
418{
419 pthread_lock *thelock = (pthread_lock *)lock;
420 int status, error = 0;
421
422 dprintf(("PyThread_free_lock(%p) called\n", lock));
423
424 status = pthread_mutex_destroy( &thelock->mut );
425 CHECK_STATUS("pthread_mutex_destroy");
426
427 status = pthread_cond_destroy( &thelock->lock_released );
428 CHECK_STATUS("pthread_cond_destroy");
429
430 free((void *)thelock);
431}
432
433int
434PyThread_acquire_lock(PyThread_type_lock lock, int waitflag)
435{
436 int success;
437 pthread_lock *thelock = (pthread_lock *)lock;
438 int status, error = 0;
439
440 dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag));
441
442 status = pthread_mutex_lock( &thelock->mut );
443 CHECK_STATUS("pthread_mutex_lock[1]");
444 success = thelock->locked == 0;
445
446 if ( !success && waitflag ) {
447 /* continue trying until we get the lock */
448
449 /* mut must be locked by me -- part of the condition
450 * protocol */
451 while ( thelock->locked ) {
452 status = pthread_cond_wait(&thelock->lock_released,
453 &thelock->mut);
454 CHECK_STATUS("pthread_cond_wait");
455 }
456 success = 1;
457 }
458 if (success) thelock->locked = 1;
459 status = pthread_mutex_unlock( &thelock->mut );
460 CHECK_STATUS("pthread_mutex_unlock[1]");
461
462 if (error) success = 0;
463 dprintf(("PyThread_acquire_lock(%p, %d) -> %d\n", lock, waitflag, success));
464 return success;
465}
466
467void
468PyThread_release_lock(PyThread_type_lock lock)
469{
470 pthread_lock *thelock = (pthread_lock *)lock;
471 int status, error = 0;
472
473 dprintf(("PyThread_release_lock(%p) called\n", lock));
474
475 status = pthread_mutex_lock( &thelock->mut );
476 CHECK_STATUS("pthread_mutex_lock[3]");
477
478 thelock->locked = 0;
479
480 status = pthread_mutex_unlock( &thelock->mut );
481 CHECK_STATUS("pthread_mutex_unlock[3]");
482
483 /* wake up someone (anyone, if any) waiting on the lock */
484 status = pthread_cond_signal( &thelock->lock_released );
485 CHECK_STATUS("pthread_cond_signal");
486}
487
488#endif /* USE_SEMAPHORES */
489
490/* set the thread stack size.
491 * Return 0 if size is valid, -1 if size is invalid,
492 * -2 if setting stack size is not supported.
493 */
494static int
495_pythread_pthread_set_stacksize(size_t size)
496{
497#if defined(THREAD_STACK_SIZE)
498 pthread_attr_t attrs;
499 size_t tss_min;
500 int rc = 0;
501#endif
502
503 /* set to default */
504 if (size == 0) {
505 _pythread_stacksize = 0;
506 return 0;
507 }
508
509#if defined(THREAD_STACK_SIZE)
510#if defined(PTHREAD_STACK_MIN)
511 tss_min = PTHREAD_STACK_MIN > THREAD_STACK_MIN ? PTHREAD_STACK_MIN
512 : THREAD_STACK_MIN;
513#else
514 tss_min = THREAD_STACK_MIN;
515#endif
516 if (size >= tss_min) {
517 /* validate stack size by setting thread attribute */
518 if (pthread_attr_init(&attrs) == 0) {
519 rc = pthread_attr_setstacksize(&attrs, size);
520 pthread_attr_destroy(&attrs);
521 if (rc == 0) {
522 _pythread_stacksize = size;
523 return 0;
524 }
525 }
526 }
527 return -1;
528#else
529 return -2;
530#endif
531}
532
533#define THREAD_SET_STACKSIZE(x) _pythread_pthread_set_stacksize(x)
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