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)
5 This file is part of GNU CC.
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.
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
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. */
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. */
32 * This structure represents a single mutual exclusion lock. Lock semantics
33 * are detailed with the subsequent functions. We use whatever lock is
34 * provided by the system. We augment it with depth and current owner id
35 * fields to implement and re-entrant lock.
39 volatile objc_thread_t owner; /* Id of thread that owns. */
40 volatile int depth; /* # of acquires. */
41 pthread_mutex_t lock; /* pthread mutex. */
44 /*****************************************************************************
47 static pthread_key_t __objc_thread_data_key; /* Data key for thread data.*/
51 * Initialize the threads subsystem. Returns 0 if successful, or -1 if no
52 * thread support is available.
55 __objc_init_thread_system(void)
57 printf("__objc_init_thread_system\n");
59 if (pthread_keycreate(&__objc_thread_data_key, NULL) == 0)
60 return 0; /* Yes, return success. */
62 return -1; /* Failed. */
66 __objc_fini_thread_system(void)
72 * Create a new thread of execution and return its id. Return NULL if fails.
73 * The new thread starts in "func" with the given argument.
76 objc_thread_create(void (*func)(void *arg), void *arg)
78 objc_thread_t thread_id = NULL; /* Detached thread id. */
79 pthread_t new_thread_handle; /* DCE thread handle. */
81 objc_mutex_lock(__objc_runtime_mutex);
83 if (pthread_create(&new_thread_handle, pthread_attr_default,
84 (void *)func, arg) == 0) {
85 /* ??? May not work! (64bit)*/
86 thread_id = *(objc_thread_t *)&new_thread_handle;
87 pthread_detach(&new_thread_handle); /* Fully detach thread. */
88 __objc_runtime_threads_alive++;
91 objc_mutex_unlock(__objc_runtime_mutex);
96 * Set the current thread's priority.
99 objc_thread_set_priority(int priority)
101 int sys_priority = 0;
104 case OBJC_THREAD_INTERACTIVE_PRIORITY:
105 sys_priority = (PRI_FG_MIN_NP + PRI_FG_MAX_NP) / 2;
108 case OBJC_THREAD_BACKGROUND_PRIORITY:
109 sys_priority = (PRI_BG_MIN_NP + PRI_BG_MAX_NP) / 2;
111 case OBJC_THREAD_LOW_PRIORITY:
112 sys_priority = (PRI_BG_MIN_NP + PRI_BG_MAX_NP) / 2;
116 if (pthread_setprio(pthread_self(), sys_priority) >= 0)
117 return 0; /* Changed priority. End. */
119 return -1; /* Failed. */
123 * Return the current thread's priority.
126 objc_thread_get_priority(void)
128 int sys_priority; /* DCE thread priority. */
130 if ((sys_priority = pthread_getprio(pthread_self())) >= 0) {
131 if (sys_priority >= PRI_FG_MIN_NP && sys_priority <= PRI_FG_MAX_NP)
132 return OBJC_THREAD_INTERACTIVE_PRIORITY;
133 if (sys_priority >= PRI_BG_MIN_NP && sys_priority <= PRI_BG_MAX_NP)
134 return OBJC_THREAD_BACKGROUND_PRIORITY;
135 return OBJC_THREAD_LOW_PRIORITY;
137 return -1; /* Couldn't get priority. */
141 * Yield our process time to another thread. Any BUSY waiting that is done
142 * by a thread should use this function to make sure that other threads can
143 * make progress even on a lazy uniprocessor system.
146 objc_thread_yield(void)
148 pthread_yield(); /* Yield to equal thread. */
152 * Terminate the current tread. Doesn't return anything. Doesn't return.
153 * Actually, if it failed returns -1.
156 objc_thread_exit(void)
158 objc_mutex_lock(__objc_runtime_mutex);
159 __objc_runtime_threads_alive--;
160 objc_mutex_unlock(__objc_runtime_mutex);
162 pthread_exit(&__objc_thread_exit_status); /* Terminate thread. */
167 * Returns an integer value which uniquely describes a thread. Must not be
168 * -1 which is reserved as a marker for "no thread".
173 pthread_t self = pthread_self();
175 return (objc_thread_t) pthread_getuniqe_np (&self);
179 * Sets the thread's local storage pointer. Returns 0 if successful or -1
183 objc_thread_set_data(void *value)
185 if (pthread_setspecific(__objc_thread_data_key, (void *)value) == 0)
186 return 0; /* Return thread data. */
191 * Returns the thread's local storage pointer. Returns NULL on failure.
194 objc_thread_get_data(void)
198 if (pthread_getspecific(__objc_thread_data_key, (void *)&value) == 0)
199 return value; /* Return thread data. */
205 * Allocate a mutex. Return the mutex pointer if successful or NULL if
206 * the allocation fails for any reason.
209 objc_mutex_allocate(void)
214 if (!(mutex = (objc_mutex_t)objc_malloc(sizeof(struct objc_mutex))))
215 return NULL; /* Abort if malloc failed. */
217 err = pthread_mutex_init(&mutex->lock, pthread_mutexattr_default);
219 if (err != 0) { /* System init failed? */
220 objc_free(mutex); /* Yes, free local memory. */
221 return NULL; /* Abort. */
223 mutex->owner = (objc_thread_t) -1; /* No owner. */
224 mutex->depth = 0; /* No locks. */
225 return mutex; /* Return mutex handle. */
229 * Deallocate a mutex. Note that this includes an implicit mutex_lock to
230 * insure that no one else is using the lock. It is legal to deallocate
231 * a lock if we have a lock on it, but illegal to deallotcate a lock held
233 * Returns the number of locks on the thread. (1 for deallocate).
236 objc_mutex_deallocate(objc_mutex_t mutex)
238 int depth; /* # of locks on mutex. */
240 if (!mutex) /* Is argument bad? */
241 return -1; /* Yes, abort. */
242 depth = objc_mutex_lock(mutex); /* Must have lock. */
244 pthread_mutex_unlock(&mutex->lock); /* Must unlock system mutex.*/
245 pthread_mutex_destroy(&mutex->lock); /* Free system mutex. */
247 objc_free(mutex); /* Free memory. */
248 return depth; /* Return last depth. */
252 * Grab a lock on a mutex. If this thread already has a lock on this mutex
253 * then we increment the lock count. If another thread has a lock on the
254 * mutex we block and wait for the thread to release the lock.
255 * Returns the lock count on the mutex held by this thread.
258 objc_mutex_lock(objc_mutex_t mutex)
260 objc_thread_t thread_id; /* Cache our thread id. */
262 if (!mutex) /* Is argument bad? */
263 return -1; /* Yes, abort. */
264 thread_id = objc_thread_id(); /* Get this thread's id. */
265 if (mutex->owner == thread_id) /* Already own lock? */
266 return ++mutex->depth; /* Yes, increment depth. */
268 if (pthread_mutex_lock(&mutex->lock) != 0) /* Lock DCE system mutex. */
269 return -1; /* Failed, abort. */
271 mutex->owner = thread_id; /* Mark thread as owner. */
272 return mutex->depth = 1; /* Increment depth to end. */
276 * Try to grab a lock on a mutex. If this thread already has a lock on
277 * this mutex then we increment the lock count and return it. If another
278 * thread has a lock on the mutex returns -1.
281 objc_mutex_trylock(objc_mutex_t mutex)
283 objc_thread_t thread_id; /* Cache our thread id. */
285 if (!mutex) /* Is argument bad? */
286 return -1; /* Yes, abort. */
287 thread_id = objc_thread_id(); /* Get this thread's id. */
288 if (mutex->owner == thread_id) /* Already own lock? */
289 return ++mutex->depth; /* Yes, increment depth. */
291 if (pthread_mutex_trylock(&mutex->lock) != 1) /* Lock DCE system mutex. */
292 return -1; /* Failed, abort. */
294 mutex->owner = thread_id; /* Mark thread as owner. */
295 return mutex->depth = 1; /* Increment depth to end. */
299 * Decrements the lock count on this mutex by one. If the lock count reaches
300 * zero, release the lock on the mutex. Returns the lock count on the mutex.
301 * It is an error to attempt to unlock a mutex which this thread doesn't hold
302 * in which case return -1 and the mutex is unaffected.
303 * Will also return -1 if the mutex free fails.
306 objc_mutex_unlock(objc_mutex_t mutex)
308 objc_thread_t thread_id; /* Cache our thread id. */
310 if (!mutex) /* Is argument bad? */
311 return -1; /* Yes, abort. */
312 thread_id = objc_thread_id(); /* Get this thread's id. */
313 if (mutex->owner != thread_id) /* Does some else own lock? */
314 return -1; /* Yes, abort. */
315 if (mutex->depth > 1) /* Released last lock? */
316 return --mutex->depth; /* No, Decrement depth, end.*/
317 mutex->depth = 0; /* Yes, reset depth to 0. */
318 mutex->owner = (objc_thread_t) -1; /* Set owner to "no thread".*/
320 if (pthread_mutex_unlock(&mutex->lock) != 0) /* Unlock system mutex. */
321 return -1; /* Failed, abort. */
323 return 0; /* No, return success. */