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88e17b57 BE |
1 | /* GNU Objective C Runtime Thread Interface |
2 | Copyright (C) 1996, 1997 Free Software Foundation, Inc. | |
3 | Contributed by Galen C. Hunt (gchunt@cs.rochester.edu) | |
4 | ||
38709cad | 5 | This file is part of GCC. |
88e17b57 | 6 | |
38709cad | 7 | GCC is free software; you can redistribute it and/or modify it under the |
88e17b57 BE |
8 | terms of the GNU General Public License as published by the Free Software |
9 | Foundation; either version 2, or (at your option) any later version. | |
10 | ||
38709cad | 11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
88e17b57 BE |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for more | |
14 | details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License along with | |
38709cad | 17 | GCC; see the file COPYING. If not, write to the Free Software |
f9d09c43 KC |
18 | Foundation, 51 Franklin Street, Fifth Floor, |
19 | Boston, MA 02110-1301, USA. */ | |
88e17b57 BE |
20 | |
21 | /* As a special exception, if you link this library with files compiled with | |
22 | GCC to produce an executable, this does not cause the resulting executable | |
23 | to be covered by the GNU General Public License. This exception does not | |
24 | however invalidate any other reasons why the executable file might be | |
25 | covered by the GNU General Public License. */ | |
26 | ||
27 | #include <stdlib.h> | |
348a3445 | 28 | #include "objc/runtime.h" |
88e17b57 BE |
29 | |
30 | /* Global exit status. */ | |
31 | int __objc_thread_exit_status = 0; | |
32 | ||
33 | /* Flag which lets us know if we ever became multi threaded */ | |
34 | int __objc_is_multi_threaded = 0; | |
35 | ||
36 | /* The hook function called when the runtime becomes multi threaded */ | |
37 | objc_thread_callback _objc_became_multi_threaded = NULL; | |
38 | ||
39 | /* | |
40 | Use this to set the hook function that will be called when the | |
41 | runtime initially becomes multi threaded. | |
42 | The hook function is only called once, meaning only when the | |
43 | 2nd thread is spawned, not for each and every thread. | |
44 | ||
45 | It returns the previous hook function or NULL if there is none. | |
46 | ||
47 | A program outside of the runtime could set this to some function so | |
48 | it can be informed; for example, the GNUstep Base Library sets it | |
49 | so it can implement the NSBecomingMultiThreaded notification. | |
50 | */ | |
40165636 | 51 | objc_thread_callback objc_set_thread_callback (objc_thread_callback func) |
88e17b57 BE |
52 | { |
53 | objc_thread_callback temp = _objc_became_multi_threaded; | |
54 | _objc_became_multi_threaded = func; | |
55 | return temp; | |
56 | } | |
57 | ||
58 | /* | |
59 | Private functions | |
60 | ||
61 | These functions are utilized by the frontend, but they are not | |
62 | considered part of the public interface. | |
63 | */ | |
64 | ||
65 | /* | |
66 | First function called in a thread, starts everything else. | |
67 | ||
68 | This function is passed to the backend by objc_thread_detach | |
69 | as the starting function for a new thread. | |
70 | */ | |
71 | struct __objc_thread_start_state | |
72 | { | |
73 | SEL selector; | |
74 | id object; | |
75 | id argument; | |
76 | }; | |
77 | ||
bc012a44 AP |
78 | static void __attribute__((noreturn)) |
79 | __objc_thread_detach_function (struct __objc_thread_start_state *istate) | |
88e17b57 BE |
80 | { |
81 | /* Valid state? */ | |
82 | if (istate) { | |
40165636 | 83 | id (*imp) (id, SEL, id); |
88e17b57 BE |
84 | SEL selector = istate->selector; |
85 | id object = istate->object; | |
86 | id argument = istate->argument; | |
87 | ||
88 | /* Don't need anymore so free it */ | |
40165636 | 89 | objc_free (istate); |
88e17b57 BE |
90 | |
91 | /* Clear out the thread local storage */ | |
40165636 | 92 | objc_thread_set_data (NULL); |
88e17b57 BE |
93 | |
94 | /* Check to see if we just became multi threaded */ | |
40165636 | 95 | if (! __objc_is_multi_threaded) |
88e17b57 BE |
96 | { |
97 | __objc_is_multi_threaded = 1; | |
98 | ||
99 | /* Call the hook function */ | |
100 | if (_objc_became_multi_threaded != NULL) | |
40165636 | 101 | (*_objc_became_multi_threaded) (); |
88e17b57 BE |
102 | } |
103 | ||
104 | /* Call the method */ | |
40165636 RB |
105 | if ((imp = (id (*) (id, SEL, id))objc_msg_lookup (object, selector))) |
106 | (*imp) (object, selector, argument); | |
88e17b57 | 107 | else |
40165636 RB |
108 | objc_error (object, OBJC_ERR_UNIMPLEMENTED, |
109 | "objc_thread_detach called with bad selector.\n"); | |
88e17b57 BE |
110 | } |
111 | else | |
40165636 RB |
112 | objc_error (nil, OBJC_ERR_BAD_STATE, |
113 | "objc_thread_detach called with NULL state.\n"); | |
88e17b57 BE |
114 | |
115 | /* Exit the thread */ | |
40165636 | 116 | objc_thread_exit (); |
b15b7ef8 KT |
117 | |
118 | /* Make sure compiler detects no return. */ | |
119 | __builtin_trap (); | |
88e17b57 BE |
120 | } |
121 | ||
122 | /* | |
123 | Frontend functions | |
124 | ||
125 | These functions constitute the public interface to the Objective-C thread | |
126 | and mutex functionality. | |
127 | */ | |
128 | ||
129 | /* Frontend thread functions */ | |
130 | ||
131 | /* | |
132 | Detach a new thread of execution and return its id. Returns NULL if fails. | |
133 | Thread is started by sending message with selector to object. Message | |
134 | takes a single argument. | |
135 | */ | |
136 | objc_thread_t | |
40165636 | 137 | objc_thread_detach (SEL selector, id object, id argument) |
88e17b57 BE |
138 | { |
139 | struct __objc_thread_start_state *istate; | |
140 | objc_thread_t thread_id = NULL; | |
141 | ||
142 | /* Allocate the state structure */ | |
40165636 RB |
143 | if (! (istate = (struct __objc_thread_start_state *) |
144 | objc_malloc (sizeof (*istate)))) | |
88e17b57 BE |
145 | return NULL; |
146 | ||
147 | /* Initialize the state structure */ | |
148 | istate->selector = selector; | |
149 | istate->object = object; | |
150 | istate->argument = argument; | |
151 | ||
152 | /* lock access */ | |
40165636 | 153 | objc_mutex_lock (__objc_runtime_mutex); |
88e17b57 BE |
154 | |
155 | /* Call the backend to spawn the thread */ | |
40165636 RB |
156 | if ((thread_id = __objc_thread_detach ((void *)__objc_thread_detach_function, |
157 | istate)) == NULL) | |
88e17b57 BE |
158 | { |
159 | /* failed! */ | |
40165636 RB |
160 | objc_mutex_unlock (__objc_runtime_mutex); |
161 | objc_free (istate); | |
88e17b57 BE |
162 | return NULL; |
163 | } | |
164 | ||
165 | /* Increment our thread counter */ | |
166 | __objc_runtime_threads_alive++; | |
40165636 | 167 | objc_mutex_unlock (__objc_runtime_mutex); |
88e17b57 BE |
168 | |
169 | return thread_id; | |
170 | } | |
171 | ||
172 | /* Set the current thread's priority. */ | |
173 | int | |
40165636 | 174 | objc_thread_set_priority (int priority) |
88e17b57 BE |
175 | { |
176 | /* Call the backend */ | |
40165636 | 177 | return __objc_thread_set_priority (priority); |
88e17b57 BE |
178 | } |
179 | ||
180 | /* Return the current thread's priority. */ | |
181 | int | |
40165636 | 182 | objc_thread_get_priority (void) |
88e17b57 BE |
183 | { |
184 | /* Call the backend */ | |
40165636 | 185 | return __objc_thread_get_priority (); |
88e17b57 BE |
186 | } |
187 | ||
188 | /* | |
189 | Yield our process time to another thread. Any BUSY waiting that is done | |
190 | by a thread should use this function to make sure that other threads can | |
191 | make progress even on a lazy uniprocessor system. | |
192 | */ | |
193 | void | |
40165636 | 194 | objc_thread_yield (void) |
88e17b57 BE |
195 | { |
196 | /* Call the backend */ | |
40165636 | 197 | __objc_thread_yield (); |
88e17b57 BE |
198 | } |
199 | ||
200 | /* | |
201 | Terminate the current tread. Doesn't return. | |
202 | Actually, if it failed returns -1. | |
203 | */ | |
204 | int | |
40165636 | 205 | objc_thread_exit (void) |
88e17b57 BE |
206 | { |
207 | /* Decrement our counter of the number of threads alive */ | |
40165636 | 208 | objc_mutex_lock (__objc_runtime_mutex); |
88e17b57 | 209 | __objc_runtime_threads_alive--; |
40165636 | 210 | objc_mutex_unlock (__objc_runtime_mutex); |
88e17b57 BE |
211 | |
212 | /* Call the backend to terminate the thread */ | |
40165636 | 213 | return __objc_thread_exit (); |
88e17b57 BE |
214 | } |
215 | ||
216 | /* | |
217 | Returns an integer value which uniquely describes a thread. Must not be | |
218 | NULL which is reserved as a marker for "no thread". | |
219 | */ | |
220 | objc_thread_t | |
40165636 | 221 | objc_thread_id (void) |
88e17b57 BE |
222 | { |
223 | /* Call the backend */ | |
40165636 | 224 | return __objc_thread_id (); |
88e17b57 BE |
225 | } |
226 | ||
227 | /* | |
228 | Sets the thread's local storage pointer. | |
229 | Returns 0 if successful or -1 if failed. | |
230 | */ | |
231 | int | |
40165636 | 232 | objc_thread_set_data (void *value) |
88e17b57 BE |
233 | { |
234 | /* Call the backend */ | |
40165636 | 235 | return __objc_thread_set_data (value); |
88e17b57 BE |
236 | } |
237 | ||
238 | /* | |
239 | Returns the thread's local storage pointer. Returns NULL on failure. | |
240 | */ | |
241 | void * | |
40165636 | 242 | objc_thread_get_data (void) |
88e17b57 BE |
243 | { |
244 | /* Call the backend */ | |
40165636 | 245 | return __objc_thread_get_data (); |
88e17b57 BE |
246 | } |
247 | ||
248 | /* Frontend mutex functions */ | |
249 | ||
250 | /* | |
251 | Allocate a mutex. Return the mutex pointer if successful or NULL if the | |
252 | allocation failed for any reason. | |
253 | */ | |
254 | objc_mutex_t | |
40165636 | 255 | objc_mutex_allocate (void) |
88e17b57 BE |
256 | { |
257 | objc_mutex_t mutex; | |
258 | ||
259 | /* Allocate the mutex structure */ | |
40165636 | 260 | if (! (mutex = (objc_mutex_t)objc_malloc (sizeof (struct objc_mutex)))) |
88e17b57 BE |
261 | return NULL; |
262 | ||
263 | /* Call backend to create the mutex */ | |
40165636 | 264 | if (__objc_mutex_allocate (mutex)) |
88e17b57 BE |
265 | { |
266 | /* failed! */ | |
40165636 | 267 | objc_free (mutex); |
88e17b57 BE |
268 | return NULL; |
269 | } | |
270 | ||
271 | /* Initialize mutex */ | |
272 | mutex->owner = NULL; | |
273 | mutex->depth = 0; | |
274 | return mutex; | |
275 | } | |
276 | ||
277 | /* | |
278 | Deallocate a mutex. Note that this includes an implicit mutex_lock to | |
279 | insure that no one else is using the lock. It is legal to deallocate | |
280 | a lock if we have a lock on it, but illegal to deallocate a lock held | |
281 | by anyone else. | |
282 | Returns the number of locks on the thread. (1 for deallocate). | |
283 | */ | |
284 | int | |
40165636 | 285 | objc_mutex_deallocate (objc_mutex_t mutex) |
88e17b57 BE |
286 | { |
287 | int depth; | |
288 | ||
289 | /* Valid mutex? */ | |
40165636 | 290 | if (! mutex) |
88e17b57 BE |
291 | return -1; |
292 | ||
293 | /* Acquire lock on mutex */ | |
40165636 | 294 | depth = objc_mutex_lock (mutex); |
88e17b57 BE |
295 | |
296 | /* Call backend to destroy mutex */ | |
40165636 | 297 | if (__objc_mutex_deallocate (mutex)) |
88e17b57 BE |
298 | return -1; |
299 | ||
300 | /* Free the mutex structure */ | |
40165636 | 301 | objc_free (mutex); |
88e17b57 BE |
302 | |
303 | /* Return last depth */ | |
304 | return depth; | |
305 | } | |
306 | ||
307 | /* | |
308 | Grab a lock on a mutex. If this thread already has a lock on this mutex | |
309 | then we increment the lock count. If another thread has a lock on the | |
310 | mutex we block and wait for the thread to release the lock. | |
311 | Returns the lock count on the mutex held by this thread. | |
312 | */ | |
313 | int | |
40165636 | 314 | objc_mutex_lock (objc_mutex_t mutex) |
88e17b57 BE |
315 | { |
316 | objc_thread_t thread_id; | |
317 | int status; | |
318 | ||
319 | /* Valid mutex? */ | |
40165636 | 320 | if (! mutex) |
88e17b57 BE |
321 | return -1; |
322 | ||
323 | /* If we already own the lock then increment depth */ | |
40165636 | 324 | thread_id = __objc_thread_id (); |
88e17b57 BE |
325 | if (mutex->owner == thread_id) |
326 | return ++mutex->depth; | |
327 | ||
328 | /* Call the backend to lock the mutex */ | |
40165636 | 329 | status = __objc_mutex_lock (mutex); |
88e17b57 BE |
330 | |
331 | /* Failed? */ | |
332 | if (status) | |
333 | return status; | |
334 | ||
335 | /* Successfully locked the thread */ | |
336 | mutex->owner = thread_id; | |
337 | return mutex->depth = 1; | |
338 | } | |
339 | ||
340 | /* | |
341 | Try to grab a lock on a mutex. If this thread already has a lock on | |
342 | this mutex then we increment the lock count and return it. If another | |
343 | thread has a lock on the mutex returns -1. | |
344 | */ | |
345 | int | |
40165636 | 346 | objc_mutex_trylock (objc_mutex_t mutex) |
88e17b57 BE |
347 | { |
348 | objc_thread_t thread_id; | |
349 | int status; | |
350 | ||
351 | /* Valid mutex? */ | |
40165636 | 352 | if (! mutex) |
88e17b57 BE |
353 | return -1; |
354 | ||
355 | /* If we already own the lock then increment depth */ | |
40165636 | 356 | thread_id = __objc_thread_id (); |
88e17b57 BE |
357 | if (mutex->owner == thread_id) |
358 | return ++mutex->depth; | |
359 | ||
360 | /* Call the backend to try to lock the mutex */ | |
40165636 | 361 | status = __objc_mutex_trylock (mutex); |
88e17b57 BE |
362 | |
363 | /* Failed? */ | |
364 | if (status) | |
365 | return status; | |
366 | ||
367 | /* Successfully locked the thread */ | |
368 | mutex->owner = thread_id; | |
369 | return mutex->depth = 1; | |
370 | } | |
371 | ||
372 | /* | |
373 | Unlocks the mutex by one level. | |
374 | Decrements the lock count on this mutex by one. | |
375 | If the lock count reaches zero, release the lock on the mutex. | |
376 | Returns the lock count on the mutex. | |
377 | It is an error to attempt to unlock a mutex which this thread | |
378 | doesn't hold in which case return -1 and the mutex is unaffected. | |
379 | */ | |
380 | int | |
40165636 | 381 | objc_mutex_unlock (objc_mutex_t mutex) |
88e17b57 BE |
382 | { |
383 | objc_thread_t thread_id; | |
384 | int status; | |
385 | ||
386 | /* Valid mutex? */ | |
40165636 | 387 | if (! mutex) |
88e17b57 BE |
388 | return -1; |
389 | ||
390 | /* If another thread owns the lock then abort */ | |
40165636 | 391 | thread_id = __objc_thread_id (); |
88e17b57 BE |
392 | if (mutex->owner != thread_id) |
393 | return -1; | |
394 | ||
395 | /* Decrement depth and return */ | |
396 | if (mutex->depth > 1) | |
397 | return --mutex->depth; | |
398 | ||
399 | /* Depth down to zero so we are no longer the owner */ | |
400 | mutex->depth = 0; | |
401 | mutex->owner = NULL; | |
402 | ||
403 | /* Have the backend unlock the mutex */ | |
40165636 | 404 | status = __objc_mutex_unlock (mutex); |
88e17b57 BE |
405 | |
406 | /* Failed? */ | |
407 | if (status) | |
408 | return status; | |
409 | ||
410 | return 0; | |
411 | } | |
412 | ||
413 | /* Frontend condition mutex functions */ | |
414 | ||
415 | /* | |
416 | Allocate a condition. Return the condition pointer if successful or NULL | |
417 | if the allocation failed for any reason. | |
418 | */ | |
419 | objc_condition_t | |
40165636 | 420 | objc_condition_allocate (void) |
88e17b57 BE |
421 | { |
422 | objc_condition_t condition; | |
423 | ||
424 | /* Allocate the condition mutex structure */ | |
40165636 RB |
425 | if (! (condition = |
426 | (objc_condition_t) objc_malloc (sizeof (struct objc_condition)))) | |
88e17b57 BE |
427 | return NULL; |
428 | ||
429 | /* Call the backend to create the condition mutex */ | |
40165636 | 430 | if (__objc_condition_allocate (condition)) |
88e17b57 BE |
431 | { |
432 | /* failed! */ | |
40165636 | 433 | objc_free (condition); |
88e17b57 BE |
434 | return NULL; |
435 | } | |
436 | ||
437 | /* Success! */ | |
438 | return condition; | |
439 | } | |
440 | ||
441 | /* | |
442 | Deallocate a condition. Note that this includes an implicit | |
443 | condition_broadcast to insure that waiting threads have the opportunity | |
444 | to wake. It is legal to dealloc a condition only if no other | |
445 | thread is/will be using it. Here we do NOT check for other threads | |
446 | waiting but just wake them up. | |
447 | */ | |
448 | int | |
40165636 | 449 | objc_condition_deallocate (objc_condition_t condition) |
88e17b57 BE |
450 | { |
451 | /* Broadcast the condition */ | |
40165636 | 452 | if (objc_condition_broadcast (condition)) |
88e17b57 BE |
453 | return -1; |
454 | ||
455 | /* Call the backend to destroy */ | |
40165636 | 456 | if (__objc_condition_deallocate (condition)) |
88e17b57 BE |
457 | return -1; |
458 | ||
459 | /* Free the condition mutex structure */ | |
40165636 | 460 | objc_free (condition); |
88e17b57 BE |
461 | |
462 | return 0; | |
463 | } | |
464 | ||
465 | /* | |
40165636 RB |
466 | Wait on the condition unlocking the mutex until objc_condition_signal () |
467 | or objc_condition_broadcast () are called for the same condition. The | |
88e17b57 BE |
468 | given mutex *must* have the depth set to 1 so that it can be unlocked |
469 | here, so that someone else can lock it and signal/broadcast the condition. | |
470 | The mutex is used to lock access to the shared data that make up the | |
471 | "condition" predicate. | |
472 | */ | |
473 | int | |
40165636 | 474 | objc_condition_wait (objc_condition_t condition, objc_mutex_t mutex) |
88e17b57 BE |
475 | { |
476 | objc_thread_t thread_id; | |
477 | ||
478 | /* Valid arguments? */ | |
40165636 | 479 | if (! mutex || ! condition) |
88e17b57 BE |
480 | return -1; |
481 | ||
482 | /* Make sure we are owner of mutex */ | |
40165636 | 483 | thread_id = __objc_thread_id (); |
88e17b57 BE |
484 | if (mutex->owner != thread_id) |
485 | return -1; | |
486 | ||
487 | /* Cannot be locked more than once */ | |
488 | if (mutex->depth > 1) | |
489 | return -1; | |
490 | ||
491 | /* Virtually unlock the mutex */ | |
492 | mutex->depth = 0; | |
493 | mutex->owner = (objc_thread_t)NULL; | |
494 | ||
495 | /* Call the backend to wait */ | |
40165636 | 496 | __objc_condition_wait (condition, mutex); |
88e17b57 BE |
497 | |
498 | /* Make ourselves owner of the mutex */ | |
499 | mutex->owner = thread_id; | |
500 | mutex->depth = 1; | |
501 | ||
502 | return 0; | |
503 | } | |
504 | ||
505 | /* | |
506 | Wake up all threads waiting on this condition. It is recommended that | |
507 | the called would lock the same mutex as the threads in objc_condition_wait | |
508 | before changing the "condition predicate" and make this call and unlock it | |
509 | right away after this call. | |
510 | */ | |
511 | int | |
40165636 | 512 | objc_condition_broadcast (objc_condition_t condition) |
88e17b57 BE |
513 | { |
514 | /* Valid condition mutex? */ | |
40165636 | 515 | if (! condition) |
88e17b57 BE |
516 | return -1; |
517 | ||
40165636 | 518 | return __objc_condition_broadcast (condition); |
88e17b57 BE |
519 | } |
520 | ||
521 | /* | |
522 | Wake up one thread waiting on this condition. It is recommended that | |
523 | the called would lock the same mutex as the threads in objc_condition_wait | |
524 | before changing the "condition predicate" and make this call and unlock it | |
525 | right away after this call. | |
526 | */ | |
527 | int | |
40165636 | 528 | objc_condition_signal (objc_condition_t condition) |
88e17b57 BE |
529 | { |
530 | /* Valid condition mutex? */ | |
40165636 | 531 | if (! condition) |
88e17b57 BE |
532 | return -1; |
533 | ||
40165636 | 534 | return __objc_condition_signal (condition); |
88e17b57 BE |
535 | } |
536 | ||
b894530e NP |
537 | /* Make the objc thread system aware that a thread which is managed |
538 | (started, stopped) by external code could access objc facilities | |
539 | from now on. This is used when you are interfacing with some | |
540 | external non-objc-based environment/system - you must call | |
40165636 | 541 | objc_thread_add () before an alien thread makes any calls to |
b894530e NP |
542 | Objective-C. Do not cause the _objc_became_multi_threaded hook to |
543 | be executed. */ | |
544 | void | |
40165636 | 545 | objc_thread_add (void) |
b894530e | 546 | { |
40165636 | 547 | objc_mutex_lock (__objc_runtime_mutex); |
b894530e NP |
548 | __objc_is_multi_threaded = 1; |
549 | __objc_runtime_threads_alive++; | |
40165636 | 550 | objc_mutex_unlock (__objc_runtime_mutex); |
b894530e NP |
551 | } |
552 | ||
553 | /* Make the objc thread system aware that a thread managed (started, | |
554 | stopped) by some external code will no longer access objc and thus | |
555 | can be forgotten by the objc thread system. Call | |
40165636 | 556 | objc_thread_remove () when your alien thread is done with making |
b894530e NP |
557 | calls to Objective-C. */ |
558 | void | |
40165636 | 559 | objc_thread_remove (void) |
b894530e | 560 | { |
40165636 | 561 | objc_mutex_lock (__objc_runtime_mutex); |
b894530e | 562 | __objc_runtime_threads_alive--; |
40165636 | 563 | objc_mutex_unlock (__objc_runtime_mutex); |
b894530e NP |
564 | } |
565 | ||
88e17b57 | 566 | /* End of File */ |