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8d95e9ad | 1 | /* GNU Objective C Runtime Thread Interface |
e0d0c8a1 | 2 | Copyright (C) 1996, 1997 Free Software Foundation, Inc. |
8d95e9ad RK |
3 | Contributed by Galen C. Hunt (gchunt@cs.rochester.edu) |
4 | ||
5 | This file is part of GNU CC. | |
6 | ||
7 | GNU CC 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 2, or (at your option) any later version. | |
10 | ||
11 | GNU CC 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 | You should have received a copy of the GNU General Public License along with | |
17 | GNU CC; see the file COPYING. If not, write to the Free Software | |
18 | Foundation, 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
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> | |
28 | #include "runtime.h" | |
29 | ||
2024f9e4 RK |
30 | /* Global exit status. */ |
31 | int __objc_thread_exit_status = 0; | |
8d95e9ad | 32 | |
1717ec59 RK |
33 | /* Flag which lets us know if we ever became multi threaded */ |
34 | int __objc_is_multi_threaded = 0; | |
2024f9e4 | 35 | |
1717ec59 RK |
36 | /* The hook function called when the runtime becomes multi threaded */ |
37 | objc_thread_callback _objc_became_multi_threaded = NULL; | |
38 | ||
1717ec59 RK |
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 | */ | |
51 | objc_thread_callback objc_set_thread_callback(objc_thread_callback func) | |
52 | { | |
53 | objc_thread_callback temp = _objc_became_multi_threaded; | |
54 | _objc_became_multi_threaded = func; | |
55 | return temp; | |
56 | } | |
57 | ||
2024f9e4 RK |
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. | |
8d95e9ad RK |
70 | */ |
71 | struct __objc_thread_start_state | |
72 | { | |
2024f9e4 RK |
73 | SEL selector; |
74 | id object; | |
75 | id argument; | |
8d95e9ad RK |
76 | }; |
77 | ||
78 | static volatile void | |
79 | __objc_thread_detach_function(struct __objc_thread_start_state *istate) | |
80 | { | |
2024f9e4 RK |
81 | /* Valid state? */ |
82 | if (istate) { | |
83 | id (*imp)(id,SEL,id); | |
84 | SEL selector = istate->selector; | |
85 | id object = istate->object; | |
86 | id argument = istate->argument; | |
8d95e9ad | 87 | |
2024f9e4 RK |
88 | /* Don't need anymore so free it */ |
89 | objc_free(istate); | |
8d95e9ad | 90 | |
2024f9e4 RK |
91 | /* Clear out the thread local storage */ |
92 | objc_thread_set_data(NULL); | |
1717ec59 | 93 | |
2024f9e4 RK |
94 | /* Check to see if we just became multi threaded */ |
95 | if (!__objc_is_multi_threaded) | |
96 | { | |
97 | __objc_is_multi_threaded = 1; | |
1717ec59 | 98 | |
2024f9e4 RK |
99 | /* Call the hook function */ |
100 | if (_objc_became_multi_threaded != NULL) | |
101 | (*_objc_became_multi_threaded)(); | |
102 | } | |
1717ec59 | 103 | |
2024f9e4 RK |
104 | /* Call the method */ |
105 | if ((imp = (id(*)(id, SEL, id))objc_msg_lookup(object, selector))) | |
106 | (*imp)(object, selector, argument); | |
107 | else | |
108 | objc_error(object, OBJC_ERR_UNIMPLEMENTED, | |
109 | "objc_thread_detach called with bad selector.\n"); | |
110 | } | |
111 | else | |
112 | objc_error(nil, OBJC_ERR_BAD_STATE, | |
113 | "objc_thread_detach called with NULL state.\n"); | |
114 | ||
115 | /* Exit the thread */ | |
116 | objc_thread_exit(); | |
8d95e9ad RK |
117 | } |
118 | ||
2024f9e4 RK |
119 | /* |
120 | Frontend functions | |
121 | ||
122 | These functions constitute the public interface to the Objective-C thread | |
123 | and mutex functionality. | |
124 | */ | |
125 | ||
126 | /* Frontend thread functions */ | |
127 | ||
128 | /* | |
129 | Detach a new thread of execution and return its id. Returns NULL if fails. | |
130 | Thread is started by sending message with selector to object. Message | |
131 | takes a single argument. | |
132 | */ | |
e0d0c8a1 | 133 | objc_thread_t |
8d95e9ad RK |
134 | objc_thread_detach(SEL selector, id object, id argument) |
135 | { | |
2024f9e4 RK |
136 | struct __objc_thread_start_state *istate; |
137 | objc_thread_t thread_id = NULL; | |
8d95e9ad | 138 | |
2024f9e4 | 139 | /* Allocate the state structure */ |
8d95e9ad | 140 | if (!(istate = (struct __objc_thread_start_state *) |
2024f9e4 RK |
141 | objc_malloc(sizeof(*istate)))) |
142 | return NULL; | |
8d95e9ad | 143 | |
2024f9e4 RK |
144 | /* Initialize the state structure */ |
145 | istate->selector = selector; | |
146 | istate->object = object; | |
8d95e9ad RK |
147 | istate->argument = argument; |
148 | ||
2024f9e4 RK |
149 | /* lock access */ |
150 | objc_mutex_lock(__objc_runtime_mutex); | |
151 | ||
152 | /* Call the backend to spawn the thread */ | |
153 | if ((thread_id = __objc_thread_detach((void *)__objc_thread_detach_function, | |
154 | istate)) == NULL) | |
155 | { | |
156 | /* failed! */ | |
157 | objc_mutex_unlock(__objc_runtime_mutex); | |
158 | objc_free(istate); | |
159 | return NULL; | |
160 | } | |
161 | ||
162 | /* Increment our thread counter */ | |
163 | __objc_runtime_threads_alive++; | |
164 | objc_mutex_unlock(__objc_runtime_mutex); | |
1717ec59 | 165 | |
8d95e9ad RK |
166 | return thread_id; |
167 | } | |
168 | ||
2024f9e4 RK |
169 | /* Set the current thread's priority. */ |
170 | int | |
171 | objc_thread_set_priority(int priority) | |
172 | { | |
173 | /* Call the backend */ | |
174 | return __objc_thread_set_priority(priority); | |
175 | } | |
8d95e9ad | 176 | |
2024f9e4 | 177 | /* Return the current thread's priority. */ |
8d95e9ad | 178 | int |
2024f9e4 | 179 | objc_thread_get_priority(void) |
8d95e9ad | 180 | { |
2024f9e4 RK |
181 | /* Call the backend */ |
182 | return __objc_thread_get_priority(); | |
8d95e9ad RK |
183 | } |
184 | ||
2024f9e4 RK |
185 | /* |
186 | Yield our process time to another thread. Any BUSY waiting that is done | |
187 | by a thread should use this function to make sure that other threads can | |
188 | make progress even on a lazy uniprocessor system. | |
189 | */ | |
190 | void | |
191 | objc_thread_yield(void) | |
192 | { | |
193 | /* Call the backend */ | |
194 | __objc_thread_yield(); | |
195 | } | |
196 | ||
197 | /* | |
198 | Terminate the current tread. Doesn't return. | |
199 | Actually, if it failed returns -1. | |
200 | */ | |
8d95e9ad | 201 | int |
2024f9e4 | 202 | objc_thread_exit(void) |
8d95e9ad | 203 | { |
2024f9e4 RK |
204 | /* Decrement our counter of the number of threads alive */ |
205 | objc_mutex_lock(__objc_runtime_mutex); | |
206 | __objc_runtime_threads_alive--; | |
207 | objc_mutex_unlock(__objc_runtime_mutex); | |
208 | ||
209 | /* Call the backend to terminate the thread */ | |
210 | return __objc_thread_exit(); | |
211 | } | |
212 | ||
213 | /* | |
214 | Returns an integer value which uniquely describes a thread. Must not be | |
215 | NULL which is reserved as a marker for "no thread". | |
216 | */ | |
217 | objc_thread_t | |
218 | objc_thread_id(void) | |
219 | { | |
220 | /* Call the backend */ | |
221 | return __objc_thread_id(); | |
222 | } | |
223 | ||
224 | /* | |
225 | Sets the thread's local storage pointer. | |
226 | Returns 0 if successful or -1 if failed. | |
227 | */ | |
228 | int | |
229 | objc_thread_set_data(void *value) | |
230 | { | |
231 | /* Call the backend */ | |
232 | return __objc_thread_set_data(value); | |
233 | } | |
234 | ||
235 | /* | |
236 | Returns the thread's local storage pointer. Returns NULL on failure. | |
237 | */ | |
238 | void * | |
239 | objc_thread_get_data(void) | |
240 | { | |
241 | /* Call the backend */ | |
242 | return __objc_thread_get_data(); | |
243 | } | |
244 | ||
245 | /* Frontend mutex functions */ | |
246 | ||
247 | /* | |
248 | Allocate a mutex. Return the mutex pointer if successful or NULL if the | |
249 | allocation failed for any reason. | |
250 | */ | |
251 | objc_mutex_t | |
252 | objc_mutex_allocate(void) | |
253 | { | |
254 | objc_mutex_t mutex; | |
255 | ||
256 | /* Allocate the mutex structure */ | |
257 | if (!(mutex = (objc_mutex_t)objc_malloc(sizeof(struct objc_mutex)))) | |
258 | return NULL; | |
259 | ||
260 | /* Call backend to create the mutex */ | |
261 | if (__objc_mutex_allocate(mutex)) | |
262 | { | |
263 | /* failed! */ | |
264 | objc_free(mutex); | |
265 | return NULL; | |
266 | } | |
267 | ||
268 | /* Initialize mutex */ | |
269 | mutex->owner = NULL; | |
270 | mutex->depth = 0; | |
271 | return mutex; | |
272 | } | |
273 | ||
274 | /* | |
275 | Deallocate a mutex. Note that this includes an implicit mutex_lock to | |
276 | insure that no one else is using the lock. It is legal to deallocate | |
277 | a lock if we have a lock on it, but illegal to deallocate a lock held | |
278 | by anyone else. | |
279 | Returns the number of locks on the thread. (1 for deallocate). | |
280 | */ | |
281 | int | |
282 | objc_mutex_deallocate(objc_mutex_t mutex) | |
283 | { | |
284 | int depth; | |
285 | ||
286 | /* Valid mutex? */ | |
287 | if (!mutex) | |
288 | return -1; | |
289 | ||
290 | /* Acquire lock on mutex */ | |
291 | depth = objc_mutex_lock(mutex); | |
292 | ||
293 | /* Call backend to destroy mutex */ | |
294 | if (__objc_mutex_deallocate(mutex)) | |
295 | return -1; | |
296 | ||
297 | /* Free the mutex structure */ | |
298 | objc_free(mutex); | |
299 | ||
300 | /* Return last depth */ | |
301 | return depth; | |
302 | } | |
303 | ||
304 | /* | |
305 | Grab a lock on a mutex. If this thread already has a lock on this mutex | |
306 | then we increment the lock count. If another thread has a lock on the | |
307 | mutex we block and wait for the thread to release the lock. | |
308 | Returns the lock count on the mutex held by this thread. | |
309 | */ | |
310 | int | |
311 | objc_mutex_lock(objc_mutex_t mutex) | |
312 | { | |
313 | objc_thread_t thread_id; | |
314 | int status; | |
315 | ||
316 | /* Valid mutex? */ | |
317 | if (!mutex) | |
318 | return -1; | |
319 | ||
320 | /* If we already own the lock then increment depth */ | |
321 | thread_id = objc_thread_id(); | |
322 | if (mutex->owner == thread_id) | |
323 | return ++mutex->depth; | |
324 | ||
325 | /* Call the backend to lock the mutex */ | |
326 | status = __objc_mutex_lock(mutex); | |
327 | ||
328 | /* Failed? */ | |
329 | if (status) | |
330 | return status; | |
331 | ||
332 | /* Successfully locked the thread */ | |
333 | mutex->owner = thread_id; | |
334 | return mutex->depth = 1; | |
335 | } | |
336 | ||
337 | /* | |
338 | Try to grab a lock on a mutex. If this thread already has a lock on | |
339 | this mutex then we increment the lock count and return it. If another | |
340 | thread has a lock on the mutex returns -1. | |
341 | */ | |
342 | int | |
343 | objc_mutex_trylock(objc_mutex_t mutex) | |
344 | { | |
345 | objc_thread_t thread_id; | |
346 | int status; | |
347 | ||
348 | /* Valid mutex? */ | |
349 | if (!mutex) | |
350 | return -1; | |
351 | ||
352 | /* If we already own the lock then increment depth */ | |
353 | thread_id = objc_thread_id(); | |
354 | if (mutex->owner == thread_id) | |
355 | return ++mutex->depth; | |
356 | ||
357 | /* Call the backend to try to lock the mutex */ | |
358 | status = __objc_mutex_trylock(mutex); | |
359 | ||
360 | /* Failed? */ | |
361 | if (status) | |
362 | return status; | |
363 | ||
364 | /* Successfully locked the thread */ | |
365 | mutex->owner = thread_id; | |
366 | return mutex->depth = 1; | |
367 | } | |
368 | ||
369 | /* | |
370 | Unlocks the mutex by one level. | |
371 | Decrements the lock count on this mutex by one. | |
372 | If the lock count reaches zero, release the lock on the mutex. | |
373 | Returns the lock count on the mutex. | |
374 | It is an error to attempt to unlock a mutex which this thread | |
375 | doesn't hold in which case return -1 and the mutex is unaffected. | |
376 | */ | |
377 | int | |
378 | objc_mutex_unlock(objc_mutex_t mutex) | |
379 | { | |
380 | objc_thread_t thread_id; | |
381 | int status; | |
382 | ||
383 | /* Valid mutex? */ | |
384 | if (!mutex) | |
385 | return -1; | |
386 | ||
387 | /* If another thread owns the lock then abort */ | |
388 | thread_id = objc_thread_id(); | |
389 | if (mutex->owner != thread_id) | |
390 | return -1; | |
391 | ||
392 | /* Decrement depth and return */ | |
393 | if (mutex->depth > 1) | |
394 | return --mutex->depth; | |
395 | ||
396 | /* Depth down to zero so we are no longer the owner */ | |
397 | mutex->depth = 0; | |
398 | mutex->owner = NULL; | |
399 | ||
400 | /* Have the backend unlock the mutex */ | |
401 | status = __objc_mutex_unlock(mutex); | |
402 | ||
403 | /* Failed? */ | |
404 | if (status) | |
405 | return status; | |
406 | ||
407 | return 0; | |
408 | } | |
409 | ||
410 | /* Frontend condition mutex functions */ | |
411 | ||
412 | /* | |
413 | Allocate a condition. Return the condition pointer if successful or NULL | |
414 | if the allocation failed for any reason. | |
415 | */ | |
416 | objc_condition_t | |
417 | objc_condition_allocate(void) | |
418 | { | |
419 | objc_condition_t condition; | |
420 | ||
421 | /* Allocate the condition mutex structure */ | |
422 | if (!(condition = | |
423 | (objc_condition_t)objc_malloc(sizeof(struct objc_condition)))) | |
424 | return NULL; | |
425 | ||
426 | /* Call the backend to create the condition mutex */ | |
427 | if (__objc_condition_allocate(condition)) | |
428 | { | |
429 | /* failed! */ | |
430 | objc_free(condition); | |
431 | return NULL; | |
432 | } | |
433 | ||
434 | /* Success! */ | |
435 | return condition; | |
436 | } | |
437 | ||
438 | /* | |
439 | Deallocate a condition. Note that this includes an implicit | |
440 | condition_broadcast to insure that waiting threads have the opportunity | |
441 | to wake. It is legal to dealloc a condition only if no other | |
442 | thread is/will be using it. Here we do NOT check for other threads | |
443 | waiting but just wake them up. | |
444 | */ | |
445 | int | |
446 | objc_condition_deallocate(objc_condition_t condition) | |
447 | { | |
448 | /* Broadcast the condition */ | |
449 | if (objc_condition_broadcast(condition)) | |
450 | return -1; | |
451 | ||
452 | /* Call the backend to destroy */ | |
453 | if (__objc_condition_deallocate(condition)) | |
454 | return -1; | |
455 | ||
456 | /* Free the condition mutex structure */ | |
457 | objc_free(condition); | |
458 | ||
459 | return 0; | |
460 | } | |
461 | ||
462 | /* | |
463 | Wait on the condition unlocking the mutex until objc_condition_signal() | |
464 | or objc_condition_broadcast() are called for the same condition. The | |
465 | given mutex *must* have the depth set to 1 so that it can be unlocked | |
466 | here, so that someone else can lock it and signal/broadcast the condition. | |
467 | The mutex is used to lock access to the shared data that make up the | |
468 | "condition" predicate. | |
469 | */ | |
470 | int | |
471 | objc_condition_wait(objc_condition_t condition, objc_mutex_t mutex) | |
472 | { | |
473 | objc_thread_t thread_id; | |
474 | ||
475 | /* Valid arguments? */ | |
476 | if (!mutex || !condition) | |
477 | return -1; | |
478 | ||
479 | /* Make sure we are owner of mutex */ | |
480 | thread_id = objc_thread_id(); | |
481 | if (mutex->owner != thread_id) | |
482 | return -1; | |
483 | ||
484 | /* Cannot be locked more than once */ | |
485 | if (mutex->depth > 1) | |
486 | return -1; | |
487 | ||
488 | /* Virtually unlock the mutex */ | |
489 | mutex->depth = 0; | |
490 | mutex->owner = (objc_thread_t)NULL; | |
491 | ||
492 | /* Call the backend to wait */ | |
493 | __objc_condition_wait(condition, mutex); | |
494 | ||
495 | /* Make ourselves owner of the mutex */ | |
496 | mutex->owner = thread_id; | |
497 | mutex->depth = 1; | |
498 | ||
499 | return 0; | |
500 | } | |
501 | ||
502 | /* | |
503 | Wake up all threads waiting on this condition. It is recommended that | |
504 | the called would lock the same mutex as the threads in objc_condition_wait | |
505 | before changing the "condition predicate" and make this call and unlock it | |
506 | right away after this call. | |
507 | */ | |
508 | int | |
509 | objc_condition_broadcast(objc_condition_t condition) | |
510 | { | |
511 | /* Valid condition mutex? */ | |
512 | if (!condition) | |
513 | return -1; | |
514 | ||
515 | return __objc_condition_broadcast(condition); | |
516 | } | |
517 | ||
518 | /* | |
519 | Wake up one thread waiting on this condition. It is recommended that | |
520 | the called would lock the same mutex as the threads in objc_condition_wait | |
521 | before changing the "condition predicate" and make this call and unlock it | |
522 | right away after this call. | |
523 | */ | |
524 | int | |
525 | objc_condition_signal(objc_condition_t condition) | |
526 | { | |
527 | /* Valid condition mutex? */ | |
528 | if (!condition) | |
529 | return -1; | |
530 | ||
531 | return __objc_condition_signal(condition); | |
8d95e9ad RK |
532 | } |
533 | ||
8d95e9ad | 534 | /* End of File */ |