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1 | /* GNU Objective C Runtime Thread Interface | |
2 | Copyright (C) 1996-2020 Free Software Foundation, Inc. | |
3 | Contributed by Galen C. Hunt (gchunt@cs.rochester.edu) | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under the | |
8 | terms of the GNU General Public License as published by the Free Software | |
9 | Foundation; either version 3, or (at your option) any later version. | |
10 | ||
11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
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 | Under Section 7 of GPL version 3, you are granted additional | |
17 | permissions described in the GCC Runtime Library Exception, version | |
18 | 3.1, as published by the Free Software Foundation. | |
19 | ||
20 | You should have received a copy of the GNU General Public License and | |
21 | a copy of the GCC Runtime Library Exception along with this program; | |
22 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | <http://www.gnu.org/licenses/>. */ | |
24 | ||
25 | #include "objc-private/common.h" | |
26 | #include "objc-private/error.h" | |
27 | #define _LIBOBJC | |
28 | #include "config.h" | |
29 | #include "tconfig.h" | |
30 | #include "coretypes.h" | |
31 | #include "tm.h" | |
32 | #include "defaults.h" | |
33 | #include "objc/thr.h" | |
34 | #include "objc/message.h" /* For objc_msg_lookup(). */ | |
35 | #include "objc/runtime.h" | |
36 | #include "objc-private/module-abi-8.h" | |
37 | #include "objc-private/runtime.h" | |
38 | #include <gthr.h> | |
39 | ||
40 | #include <stdlib.h> | |
41 | ||
42 | /* Global exit status. */ | |
43 | int __objc_thread_exit_status = 0; | |
44 | ||
45 | /* Flag which lets us know if we ever became multi threaded. */ | |
46 | int __objc_is_multi_threaded = 0; | |
47 | ||
48 | /* The hook function called when the runtime becomes multi | |
49 | threaded. */ | |
50 | objc_thread_callback _objc_became_multi_threaded = NULL; | |
51 | ||
52 | /* Use this to set the hook function that will be called when the | |
53 | runtime initially becomes multi threaded. The hook function is | |
54 | only called once, meaning only when the 2nd thread is spawned, not | |
55 | for each and every thread. | |
56 | ||
57 | It returns the previous hook function or NULL if there is none. | |
58 | ||
59 | A program outside of the runtime could set this to some function so | |
60 | it can be informed; for example, the GNUstep Base Library sets it | |
61 | so it can implement the NSBecomingMultiThreaded notification. */ | |
62 | objc_thread_callback objc_set_thread_callback (objc_thread_callback func) | |
63 | { | |
64 | objc_thread_callback temp = _objc_became_multi_threaded; | |
65 | _objc_became_multi_threaded = func; | |
66 | return temp; | |
67 | } | |
68 | ||
69 | /* Private functions. | |
70 | ||
71 | These functions are utilized by the runtime, but they are not | |
72 | considered part of the public interface. */ | |
73 | ||
74 | /* Initialize the threads subsystem. */ | |
75 | int | |
76 | __objc_init_thread_system(void) | |
77 | { | |
78 | return __gthread_objc_init_thread_system (); | |
79 | } | |
80 | ||
81 | /* First function called in a thread, starts everything else. | |
82 | ||
83 | This function is passed to the backend by objc_thread_detach as the | |
84 | starting function for a new thread. */ | |
85 | struct __objc_thread_start_state | |
86 | { | |
87 | SEL selector; | |
88 | id object; | |
89 | id argument; | |
90 | }; | |
91 | ||
92 | static void __attribute__((noreturn)) | |
93 | __objc_thread_detach_function (struct __objc_thread_start_state *istate) | |
94 | { | |
95 | /* Valid state? */ | |
96 | if (istate) | |
97 | { | |
98 | id (*imp) (id, SEL, id); | |
99 | SEL selector = istate->selector; | |
100 | id object = istate->object; | |
101 | id argument = istate->argument; | |
102 | ||
103 | /* Don't need anymore so free it. */ | |
104 | objc_free (istate); | |
105 | ||
106 | /* Clear out the thread local storage. */ | |
107 | objc_thread_set_data (NULL); | |
108 | ||
109 | /* Check to see if we just became multi threaded. */ | |
110 | if (! __objc_is_multi_threaded) | |
111 | { | |
112 | __objc_is_multi_threaded = 1; | |
113 | ||
114 | /* Call the hook function. */ | |
115 | if (_objc_became_multi_threaded != NULL) | |
116 | (*_objc_became_multi_threaded) (); | |
117 | } | |
118 | ||
119 | /* Call the method. */ | |
120 | if ((imp = (id (*) (id, SEL, id))objc_msg_lookup (object, selector))) | |
121 | (*imp) (object, selector, argument); | |
122 | else | |
123 | { | |
124 | /* FIXME: Should we abort here ? */ | |
125 | _objc_abort ("objc_thread_detach called with bad selector.\n"); | |
126 | } | |
127 | } | |
128 | else | |
129 | { | |
130 | /* FIXME: Should we abort here ? */ | |
131 | _objc_abort ("objc_thread_detach called with NULL state.\n"); | |
132 | } | |
133 | ||
134 | /* Exit the thread. */ | |
135 | objc_thread_exit (); | |
136 | ||
137 | /* Make sure compiler detects no return. */ | |
138 | __builtin_trap (); | |
139 | } | |
140 | ||
141 | /* Public functions. | |
142 | ||
143 | These functions constitute the public interface to the Objective-C | |
144 | thread and mutex functionality. */ | |
145 | ||
146 | /* Detach a new thread of execution and return its id. Returns NULL | |
147 | if fails. Thread is started by sending message with selector to | |
148 | object. Message takes a single argument. */ | |
149 | objc_thread_t | |
150 | objc_thread_detach (SEL selector, id object, id argument) | |
151 | { | |
152 | struct __objc_thread_start_state *istate; | |
153 | objc_thread_t thread_id = NULL; | |
154 | ||
155 | /* Allocate the state structure. */ | |
156 | if (!(istate = (struct __objc_thread_start_state *)objc_malloc | |
157 | (sizeof (*istate)))) | |
158 | return NULL; | |
159 | ||
160 | /* Initialize the state structure. */ | |
161 | istate->selector = selector; | |
162 | istate->object = object; | |
163 | istate->argument = argument; | |
164 | ||
165 | /* Lock access. */ | |
166 | objc_mutex_lock (__objc_runtime_mutex); | |
167 | ||
168 | /* Call the backend to spawn the thread. */ | |
169 | if ((thread_id = __gthread_objc_thread_detach ((void *)__objc_thread_detach_function, | |
170 | istate)) == NULL) | |
171 | { | |
172 | /* Failed! */ | |
173 | objc_mutex_unlock (__objc_runtime_mutex); | |
174 | objc_free (istate); | |
175 | return NULL; | |
176 | } | |
177 | ||
178 | /* Increment our thread counter. */ | |
179 | __objc_runtime_threads_alive++; | |
180 | objc_mutex_unlock (__objc_runtime_mutex); | |
181 | ||
182 | return thread_id; | |
183 | } | |
184 | ||
185 | /* Set the current thread's priority. */ | |
186 | int | |
187 | objc_thread_set_priority (int priority) | |
188 | { | |
189 | return __gthread_objc_thread_set_priority (priority); | |
190 | } | |
191 | ||
192 | /* Return the current thread's priority. */ | |
193 | int | |
194 | objc_thread_get_priority (void) | |
195 | { | |
196 | return __gthread_objc_thread_get_priority (); | |
197 | } | |
198 | ||
199 | /* Yield our process time to another thread. Any BUSY waiting that is | |
200 | done by a thread should use this function to make sure that other | |
201 | threads can make progress even on a lazy uniprocessor system. */ | |
202 | void | |
203 | objc_thread_yield (void) | |
204 | { | |
205 | __gthread_objc_thread_yield (); | |
206 | } | |
207 | ||
208 | /* Terminate the current tread. Doesn't return. Actually, if it | |
209 | failed returns -1. */ | |
210 | int | |
211 | objc_thread_exit (void) | |
212 | { | |
213 | /* Decrement our counter of the number of threads alive. */ | |
214 | objc_mutex_lock (__objc_runtime_mutex); | |
215 | __objc_runtime_threads_alive--; | |
216 | objc_mutex_unlock (__objc_runtime_mutex); | |
217 | ||
218 | /* Call the backend to terminate the thread. */ | |
219 | return __gthread_objc_thread_exit (); | |
220 | } | |
221 | ||
222 | /* Returns an integer value which uniquely describes a thread. Must | |
223 | not be NULL which is reserved as a marker for "no thread". */ | |
224 | objc_thread_t | |
225 | objc_thread_id (void) | |
226 | { | |
227 | return __gthread_objc_thread_id (); | |
228 | } | |
229 | ||
230 | /* Sets the thread's local storage pointer. Returns 0 if successful | |
231 | or -1 if failed. */ | |
232 | int | |
233 | objc_thread_set_data (void *value) | |
234 | { | |
235 | return __gthread_objc_thread_set_data (value); | |
236 | } | |
237 | ||
238 | /* Returns the thread's local storage pointer. Returns NULL on | |
239 | failure. */ | |
240 | void * | |
241 | objc_thread_get_data (void) | |
242 | { | |
243 | return __gthread_objc_thread_get_data (); | |
244 | } | |
245 | ||
246 | /* Public mutex functions */ | |
247 | ||
248 | /* Allocate a mutex. Return the mutex pointer if successful or NULL | |
249 | if the allocation failed for any reason. */ | |
250 | objc_mutex_t | |
251 | objc_mutex_allocate (void) | |
252 | { | |
253 | objc_mutex_t mutex; | |
254 | ||
255 | /* Allocate the mutex structure. */ | |
256 | if (! (mutex = (objc_mutex_t)objc_malloc (sizeof (struct objc_mutex)))) | |
257 | return NULL; | |
258 | ||
259 | /* Call backend to create the mutex. */ | |
260 | if (__gthread_objc_mutex_allocate (mutex)) | |
261 | { | |
262 | /* Failed! */ | |
263 | objc_free (mutex); | |
264 | return NULL; | |
265 | } | |
266 | ||
267 | /* Initialize mutex. */ | |
268 | mutex->owner = NULL; | |
269 | mutex->depth = 0; | |
270 | return mutex; | |
271 | } | |
272 | ||
273 | /* Deallocate a mutex. Note that this includes an implicit mutex_lock | |
274 | to insure that no one else is using the lock. It is legal to | |
275 | deallocate a lock if we have a lock on it, but illegal to | |
276 | deallocate a lock held by anyone else. Returns the number of locks | |
277 | on the thread. (1 for deallocate). */ | |
278 | int | |
279 | objc_mutex_deallocate (objc_mutex_t mutex) | |
280 | { | |
281 | int depth; | |
282 | ||
283 | /* Valid mutex? */ | |
284 | if (! mutex) | |
285 | return -1; | |
286 | ||
287 | /* Acquire lock on mutex. */ | |
288 | depth = objc_mutex_lock (mutex); | |
289 | ||
290 | /* Call backend to destroy mutex. */ | |
291 | if (__gthread_objc_mutex_deallocate (mutex)) | |
292 | return -1; | |
293 | ||
294 | /* Free the mutex structure. */ | |
295 | objc_free (mutex); | |
296 | ||
297 | /* Return last depth. */ | |
298 | return depth; | |
299 | } | |
300 | ||
301 | /* Grab a lock on a mutex. If this thread already has a lock on this | |
302 | mutex then we increment the lock count. If another thread has a | |
303 | lock on the mutex we block and wait for the thread to release the | |
304 | lock. Returns the lock count on the mutex held by this thread. */ | |
305 | int | |
306 | objc_mutex_lock (objc_mutex_t mutex) | |
307 | { | |
308 | objc_thread_t thread_id; | |
309 | int status; | |
310 | ||
311 | /* Valid mutex? */ | |
312 | if (! mutex) | |
313 | return -1; | |
314 | ||
315 | /* If we already own the lock then increment depth. */ | |
316 | thread_id = __gthread_objc_thread_id (); | |
317 | if (mutex->owner == thread_id) | |
318 | return ++mutex->depth; | |
319 | ||
320 | /* Call the backend to lock the mutex. */ | |
321 | status = __gthread_objc_mutex_lock (mutex); | |
322 | ||
323 | /* Failed? */ | |
324 | if (status) | |
325 | return status; | |
326 | ||
327 | /* Successfully locked the thread. */ | |
328 | mutex->owner = thread_id; | |
329 | return mutex->depth = 1; | |
330 | } | |
331 | ||
332 | /* Try to grab a lock on a mutex. If this thread already has a lock | |
333 | on this mutex then we increment the lock count and return it. If | |
334 | another thread has a lock on the mutex returns -1. */ | |
335 | int | |
336 | objc_mutex_trylock (objc_mutex_t mutex) | |
337 | { | |
338 | objc_thread_t thread_id; | |
339 | int status; | |
340 | ||
341 | /* Valid mutex? */ | |
342 | if (! mutex) | |
343 | return -1; | |
344 | ||
345 | /* If we already own the lock then increment depth. */ | |
346 | thread_id = __gthread_objc_thread_id (); | |
347 | if (mutex->owner == thread_id) | |
348 | return ++mutex->depth; | |
349 | ||
350 | /* Call the backend to try to lock the mutex. */ | |
351 | status = __gthread_objc_mutex_trylock (mutex); | |
352 | ||
353 | /* Failed? */ | |
354 | if (status) | |
355 | return status; | |
356 | ||
357 | /* Successfully locked the thread. */ | |
358 | mutex->owner = thread_id; | |
359 | return mutex->depth = 1; | |
360 | } | |
361 | ||
362 | /* Unlocks the mutex by one level. Decrements the lock count on this | |
363 | mutex by one. If the lock count reaches zero, release the lock on | |
364 | the mutex. Returns the lock count on the mutex. It is an error to | |
365 | attempt to unlock a mutex which this thread doesn't hold in which | |
366 | case return -1 and the mutex is unaffected. */ | |
367 | int | |
368 | objc_mutex_unlock (objc_mutex_t mutex) | |
369 | { | |
370 | objc_thread_t thread_id; | |
371 | int status; | |
372 | ||
373 | /* Valid mutex? */ | |
374 | if (! mutex) | |
375 | return -1; | |
376 | ||
377 | /* If another thread owns the lock then abort. */ | |
378 | thread_id = __gthread_objc_thread_id (); | |
379 | if (mutex->owner != thread_id) | |
380 | return -1; | |
381 | ||
382 | /* Decrement depth and return. */ | |
383 | if (mutex->depth > 1) | |
384 | return --mutex->depth; | |
385 | ||
386 | /* Depth down to zero so we are no longer the owner. */ | |
387 | mutex->depth = 0; | |
388 | mutex->owner = NULL; | |
389 | ||
390 | /* Have the backend unlock the mutex. */ | |
391 | status = __gthread_objc_mutex_unlock (mutex); | |
392 | ||
393 | /* Failed? */ | |
394 | if (status) | |
395 | return status; | |
396 | ||
397 | return 0; | |
398 | } | |
399 | ||
400 | /* Public condition mutex functions */ | |
401 | ||
402 | /* Allocate a condition. Return the condition pointer if successful | |
403 | or NULL if the allocation failed for any reason. */ | |
404 | objc_condition_t | |
405 | objc_condition_allocate (void) | |
406 | { | |
407 | objc_condition_t condition; | |
408 | ||
409 | /* Allocate the condition mutex structure. */ | |
410 | if (! (condition = | |
411 | (objc_condition_t) objc_malloc (sizeof (struct objc_condition)))) | |
412 | return NULL; | |
413 | ||
414 | /* Call the backend to create the condition mutex. */ | |
415 | if (__gthread_objc_condition_allocate (condition)) | |
416 | { | |
417 | /* Failed! */ | |
418 | objc_free (condition); | |
419 | return NULL; | |
420 | } | |
421 | ||
422 | /* Success! */ | |
423 | return condition; | |
424 | } | |
425 | ||
426 | /* Deallocate a condition. Note that this includes an implicit | |
427 | condition_broadcast to insure that waiting threads have the | |
428 | opportunity to wake. It is legal to dealloc a condition only if no | |
429 | other thread is/will be using it. Here we do NOT check for other | |
430 | threads waiting but just wake them up. */ | |
431 | int | |
432 | objc_condition_deallocate (objc_condition_t condition) | |
433 | { | |
434 | /* Broadcast the condition. */ | |
435 | if (objc_condition_broadcast (condition)) | |
436 | return -1; | |
437 | ||
438 | /* Call the backend to destroy. */ | |
439 | if (__gthread_objc_condition_deallocate (condition)) | |
440 | return -1; | |
441 | ||
442 | /* Free the condition mutex structure. */ | |
443 | objc_free (condition); | |
444 | ||
445 | return 0; | |
446 | } | |
447 | ||
448 | /* Wait on the condition unlocking the mutex until | |
449 | objc_condition_signal () or objc_condition_broadcast () are called | |
450 | for the same condition. The given mutex *must* have the depth set | |
451 | to 1 so that it can be unlocked here, so that someone else can lock | |
452 | it and signal/broadcast the condition. The mutex is used to lock | |
453 | access to the shared data that make up the "condition" | |
454 | predicate. */ | |
455 | int | |
456 | objc_condition_wait (objc_condition_t condition, objc_mutex_t mutex) | |
457 | { | |
458 | objc_thread_t thread_id; | |
459 | ||
460 | /* Valid arguments? */ | |
461 | if (! mutex || ! condition) | |
462 | return -1; | |
463 | ||
464 | /* Make sure we are owner of mutex. */ | |
465 | thread_id = __gthread_objc_thread_id (); | |
466 | if (mutex->owner != thread_id) | |
467 | return -1; | |
468 | ||
469 | /* Cannot be locked more than once. */ | |
470 | if (mutex->depth > 1) | |
471 | return -1; | |
472 | ||
473 | /* Virtually unlock the mutex. */ | |
474 | mutex->depth = 0; | |
475 | mutex->owner = (objc_thread_t)NULL; | |
476 | ||
477 | /* Call the backend to wait. */ | |
478 | __gthread_objc_condition_wait (condition, mutex); | |
479 | ||
480 | /* Make ourselves owner of the mutex. */ | |
481 | mutex->owner = thread_id; | |
482 | mutex->depth = 1; | |
483 | ||
484 | return 0; | |
485 | } | |
486 | ||
487 | /* Wake up all threads waiting on this condition. It is recommended | |
488 | that the called would lock the same mutex as the threads in | |
489 | objc_condition_wait before changing the "condition predicate" and | |
490 | make this call and unlock it right away after this call. */ | |
491 | int | |
492 | objc_condition_broadcast (objc_condition_t condition) | |
493 | { | |
494 | /* Valid condition mutex? */ | |
495 | if (! condition) | |
496 | return -1; | |
497 | ||
498 | return __gthread_objc_condition_broadcast (condition); | |
499 | } | |
500 | ||
501 | /* Wake up one thread waiting on this condition. It is recommended | |
502 | that the called would lock the same mutex as the threads in | |
503 | objc_condition_wait before changing the "condition predicate" and | |
504 | make this call and unlock it right away after this call. */ | |
505 | int | |
506 | objc_condition_signal (objc_condition_t condition) | |
507 | { | |
508 | /* Valid condition mutex? */ | |
509 | if (! condition) | |
510 | return -1; | |
511 | ||
512 | return __gthread_objc_condition_signal (condition); | |
513 | } | |
514 | ||
515 | /* Make the objc thread system aware that a thread which is managed | |
516 | (started, stopped) by external code could access objc facilities | |
517 | from now on. This is used when you are interfacing with some | |
518 | external non-objc-based environment/system - you must call | |
519 | objc_thread_add () before an alien thread makes any calls to | |
520 | Objective-C. Do not cause the _objc_became_multi_threaded hook to | |
521 | be executed. */ | |
522 | void | |
523 | objc_thread_add (void) | |
524 | { | |
525 | objc_mutex_lock (__objc_runtime_mutex); | |
526 | __objc_is_multi_threaded = 1; | |
527 | __objc_runtime_threads_alive++; | |
528 | objc_mutex_unlock (__objc_runtime_mutex); | |
529 | } | |
530 | ||
531 | /* Make the objc thread system aware that a thread managed (started, | |
532 | stopped) by some external code will no longer access objc and thus | |
533 | can be forgotten by the objc thread system. Call | |
534 | objc_thread_remove () when your alien thread is done with making | |
535 | calls to Objective-C. */ | |
536 | void | |
537 | objc_thread_remove (void) | |
538 | { | |
539 | objc_mutex_lock (__objc_runtime_mutex); | |
540 | __objc_runtime_threads_alive--; | |
541 | objc_mutex_unlock (__objc_runtime_mutex); | |
542 | } | |
543 |