1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
3 *
4 * gthread.c: MT safety related functions
5 * Copyright 1998 Sebastian Wilhelmi; University of Karlsruhe
6 * Owen Taylor
7 *
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2 of the License, or (at your option) any later version.
12 *
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the
20 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
22 */
23
24 /* Prelude {{{1 ----------------------------------------------------------- */
25
26 /*
27 * Modified by the GLib Team and others 1997-2000. See the AUTHORS
28 * file for a list of people on the GLib Team. See the ChangeLog
29 * files for a list of changes. These files are distributed with
30 * GLib at ftp://ftp.gtk.org/pub/gtk/.
31 */
32
33 /*
34 * MT safe
35 */
36
37 /* implement gthread.h's inline functions */
38 #define G_IMPLEMENT_INLINES 1
39 #define __G_THREAD_C__
40
41 #include "config.h"
42
43 #include "gthread.h"
44 #include "gthreadprivate.h"
45
46 #ifdef HAVE_UNISTD_H
47 #include <unistd.h>
48 #endif
49
50 #ifndef G_OS_WIN32
51 #include <sys/time.h>
52 #include <time.h>
53 #else
54 #include <windows.h>
55 #endif /* G_OS_WIN32 */
56
57 #include <string.h>
58
59 #include "garray.h"
60 #include "gbitlock.h"
61 #include "gslist.h"
62 #include "gtestutils.h"
63 //#include "gtimer.h"
64
65 /**
66 * SECTION:threads
67 * @title: Threads
68 * @short_description: thread abstraction; including threads, different
69 * mutexes, conditions and thread private data
70 * @see_also: #GThreadPool, #GAsyncQueue
71 *
72 * Threads act almost like processes, but unlike processes all threads
73 * of one process share the same memory. This is good, as it provides
74 * easy communication between the involved threads via this shared
75 * memory, and it is bad, because strange things (so called
76 * "Heisenbugs") might happen if the program is not carefully designed.
77 * In particular, due to the concurrent nature of threads, no
78 * assumptions on the order of execution of code running in different
79 * threads can be made, unless order is explicitly forced by the
80 * programmer through synchronization primitives.
81 *
82 * The aim of the thread related functions in GLib is to provide a
83 * portable means for writing multi-threaded software. There are
84 * primitives for mutexes to protect the access to portions of memory
85 * (#GMutex, #GStaticMutex, #G_LOCK_DEFINE, #GStaticRecMutex and
86 * #GStaticRWLock). There is a facility to use individual bits for
87 * locks (g_bit_lock()). There are primitives for condition variables to
88 * allow synchronization of threads (#GCond). There are primitives for
89 * thread-private data - data that every thread has a private instance
90 * of (#GPrivate, #GStaticPrivate). There are facilities for one-time
91 * initialization (#GOnce, g_once_init_enter()). Last but definitely
92 * not least there are primitives to portably create and manage
93 * threads (#GThread).
94 *
95 * The threading system is initialized with g_thread_init(), which
96 * takes an optional custom thread implementation or %NULL for the
97 * default implementation. If you want to call g_thread_init() with a
98 * non-%NULL argument this must be done before executing any other GLib
99 * functions (except g_mem_set_vtable()). This is a requirement even if
100 * no threads are in fact ever created by the process.
101 *
102 * Calling g_thread_init() with a %NULL argument is somewhat more
103 * relaxed. You may call any other glib functions in the main thread
104 * before g_thread_init() as long as g_thread_init() is not called from
105 * a glib callback, or with any locks held. However, many libraries
106 * above glib does not support late initialization of threads, so doing
107 * this should be avoided if possible.
108 *
109 * Please note that since version 2.24 the GObject initialization
110 * function g_type_init() initializes threads (with a %NULL argument),
111 * so most applications, including those using Gtk+ will run with
112 * threads enabled. If you want a special thread implementation, make
113 * sure you call g_thread_init() before g_type_init() is called.
114 *
115 * After calling g_thread_init(), GLib is completely thread safe (all
116 * global data is automatically locked), but individual data structure
117 * instances are not automatically locked for performance reasons. So,
118 * for example you must coordinate accesses to the same #GHashTable
119 * from multiple threads. The two notable exceptions from this rule
120 * are #GMainLoop and #GAsyncQueue, which <emphasis>are</emphasis>
121 * threadsafe and need no further application-level locking to be
122 * accessed from multiple threads.
123 *
124 * To help debugging problems in multithreaded applications, GLib
125 * supports error-checking mutexes that will give you helpful error
126 * messages on common problems. To use error-checking mutexes, define
127 * the symbol #G_ERRORCHECK_MUTEXES when compiling the application.
128 **/
129
130 /**
131 * G_THREADS_IMPL_POSIX:
132 *
133 * This macro is defined if POSIX style threads are used.
134 **/
135
136 /**
137 * G_THREADS_ENABLED:
138 *
139 * This macro is defined if GLib was compiled with thread support. This
140 * does not necessarily mean that there is a thread implementation
141 * available, but it does mean that the infrastructure is in place and
142 * that once you provide a thread implementation to g_thread_init(),
143 * GLib will be multi-thread safe. If #G_THREADS_ENABLED is not
144 * defined, then Glib is not, and cannot be, multi-thread safe.
145 **/
146
147 /**
148 * G_THREADS_IMPL_NONE:
149 *
150 * This macro is defined if no thread implementation is used. You can,
151 * however, provide one to g_thread_init() to make GLib multi-thread
152 * safe.
153 **/
154
155 /* G_LOCK Documentation {{{1 ---------------------------------------------- */
156
157 /* IMPLEMENTATION NOTE:
158 *
159 * G_LOCK_DEFINE and friends are convenience macros defined in
160 * gthread.h. Their documentation lives here.
161 */
162
163 /**
164 * G_LOCK_DEFINE:
165 * @name: the name of the lock.
166 *
167 * The %G_LOCK_* macros provide a convenient interface to #GStaticMutex
168 * with the advantage that they will expand to nothing in programs
169 * compiled against a thread-disabled GLib, saving code and memory
170 * there. #G_LOCK_DEFINE defines a lock. It can appear anywhere
171 * variable definitions may appear in programs, i.e. in the first block
172 * of a function or outside of functions. The @name parameter will be
173 * mangled to get the name of the #GStaticMutex. This means that you
174 * can use names of existing variables as the parameter - e.g. the name
175 * of the variable you intent to protect with the lock. Look at our
176 * <function>give_me_next_number()</function> example using the
177 * %G_LOCK_* macros:
178 *
179 * <example>
180 * <title>Using the %G_LOCK_* convenience macros</title>
181 * <programlisting>
182 * G_LOCK_DEFINE (current_number);
183 *
184 * int
185 * give_me_next_number (void)
186 * {
187 * static int current_number = 0;
188 * int ret_val;
189 *
190 * G_LOCK (current_number);
191 * ret_val = current_number = calc_next_number (current_number);
192 * G_UNLOCK (current_number);
193 *
194 * return ret_val;
195 * }
196 * </programlisting>
197 * </example>
198 **/
199
200 /**
201 * G_LOCK_DEFINE_STATIC:
202 * @name: the name of the lock.
203 *
204 * This works like #G_LOCK_DEFINE, but it creates a static object.
205 **/
206
207 /**
208 * G_LOCK_EXTERN:
209 * @name: the name of the lock.
210 *
211 * This declares a lock, that is defined with #G_LOCK_DEFINE in another
212 * module.
213 **/
214
215 /**
216 * G_LOCK:
217 * @name: the name of the lock.
218 *
219 * Works like g_mutex_lock(), but for a lock defined with
220 * #G_LOCK_DEFINE.
221 **/
222
223 /**
224 * G_TRYLOCK:
225 * @name: the name of the lock.
226 * @Returns: %TRUE, if the lock could be locked.
227 *
228 * Works like g_mutex_trylock(), but for a lock defined with
229 * #G_LOCK_DEFINE.
230 **/
231
232 /**
233 * G_UNLOCK:
234 * @name: the name of the lock.
235 *
236 * Works like g_mutex_unlock(), but for a lock defined with
237 * #G_LOCK_DEFINE.
238 **/
239
240 /* GThreadError {{{1 ------------------------------------------------------- */
241 /**
242 * GThreadError:
243 * @G_THREAD_ERROR_AGAIN: a thread couldn't be created due to resource
244 * shortage. Try again later.
245 *
246 * Possible errors of thread related functions.
247 **/
248
249 /**
250 * G_THREAD_ERROR:
251 *
252 * The error domain of the GLib thread subsystem.
253 **/
254 GQuark
g_thread_error_quark(void)255 g_thread_error_quark (void)
256 {
257 return g_quark_from_static_string ("g_thread_error");
258 }
259
260 /* Miscellaneous Structures {{{1 ------------------------------------------ */
261 typedef struct _GRealThread GRealThread;
262 struct _GRealThread
263 {
264 GThread thread;
265 /* Bit 0 protects private_data. To avoid deadlocks, do not block while
266 * holding this (particularly on the g_thread lock). */
267 volatile gint private_data_lock;
268 GArray *private_data;
269 GRealThread *next;
270 gpointer retval;
271 GSystemThread system_thread;
272 };
273
274 #define LOCK_PRIVATE_DATA(self) g_bit_lock (&(self)->private_data_lock, 0)
275 #define UNLOCK_PRIVATE_DATA(self) g_bit_unlock (&(self)->private_data_lock, 0)
276
277 typedef struct _GStaticPrivateNode GStaticPrivateNode;
278 struct _GStaticPrivateNode
279 {
280 gpointer data;
281 GDestroyNotify destroy;
282 };
283
284 static void g_thread_cleanup (gpointer data);
285 static void g_thread_fail (void);
286 static guint64 gettime (void);
287
288 guint64 (*g_thread_gettime) (void) = gettime;
289
290 /* Global Variables {{{1 -------------------------------------------------- */
291
292 static GSystemThread zero_thread; /* This is initialized to all zero */
293 gboolean g_thread_use_default_impl = TRUE;
294
295 /**
296 * g_thread_supported:
297 * @Returns: %TRUE, if the thread system is initialized.
298 *
299 * This function returns %TRUE if the thread system is initialized, and
300 * %FALSE if it is not.
301 *
302 * <note><para>This function is actually a macro. Apart from taking the
303 * address of it you can however use it as if it was a
304 * function.</para></note>
305 **/
306
307 /* IMPLEMENTATION NOTE:
308 *
309 * g_thread_supported() is just returns g_threads_got_initialized
310 */
311 gboolean g_threads_got_initialized = FALSE;
312
313
314 /* Thread Implementation Virtual Function Table {{{1 ---------------------- */
315 /* Virtual Function Table Documentation {{{2 ------------------------------ */
316 /**
317 * GThreadFunctions:
318 * @mutex_new: virtual function pointer for g_mutex_new()
319 * @mutex_lock: virtual function pointer for g_mutex_lock()
320 * @mutex_trylock: virtual function pointer for g_mutex_trylock()
321 * @mutex_unlock: virtual function pointer for g_mutex_unlock()
322 * @mutex_free: virtual function pointer for g_mutex_free()
323 * @cond_new: virtual function pointer for g_cond_new()
324 * @cond_signal: virtual function pointer for g_cond_signal()
325 * @cond_broadcast: virtual function pointer for g_cond_broadcast()
326 * @cond_wait: virtual function pointer for g_cond_wait()
327 * @cond_timed_wait: virtual function pointer for g_cond_timed_wait()
328 * @cond_free: virtual function pointer for g_cond_free()
329 * @private_new: virtual function pointer for g_private_new()
330 * @private_get: virtual function pointer for g_private_get()
331 * @private_set: virtual function pointer for g_private_set()
332 * @thread_create: virtual function pointer for g_thread_create()
333 * @thread_yield: virtual function pointer for g_thread_yield()
334 * @thread_join: virtual function pointer for g_thread_join()
335 * @thread_exit: virtual function pointer for g_thread_exit()
336 * @thread_set_priority: virtual function pointer for
337 * g_thread_set_priority()
338 * @thread_self: virtual function pointer for g_thread_self()
339 * @thread_equal: used internally by recursive mutex locks and by some
340 * assertion checks
341 *
342 * This function table is used by g_thread_init() to initialize the
343 * thread system. The functions in the table are directly used by their
344 * g_* prepended counterparts (described in this document). For
345 * example, if you call g_mutex_new() then mutex_new() from the table
346 * provided to g_thread_init() will be called.
347 *
348 * <note><para>Do not use this struct unless you know what you are
349 * doing.</para></note>
350 **/
351
352 /* IMPLEMENTATION NOTE:
353 *
354 * g_thread_functions_for_glib_use is a global symbol that gets used by
355 * most of the "primitive" threading calls. g_mutex_lock(), for
356 * example, is just a macro that calls the appropriate virtual function
357 * out of this table.
358 *
359 * For that reason, all of those macros are documented here.
360 */
361 GThreadFunctions g_thread_functions_for_glib_use = {
362 /* GMutex Virtual Functions {{{2 ------------------------------------------ */
363
364 /**
365 * GMutex:
366 *
367 * The #GMutex struct is an opaque data structure to represent a mutex
368 * (mutual exclusion). It can be used to protect data against shared
369 * access. Take for example the following function:
370 *
371 * <example>
372 * <title>A function which will not work in a threaded environment</title>
373 * <programlisting>
374 * int
375 * give_me_next_number (void)
376 * {
377 * static int current_number = 0;
378 *
379 * /<!-- -->* now do a very complicated calculation to calculate the new
380 * * number, this might for example be a random number generator
381 * *<!-- -->/
382 * current_number = calc_next_number (current_number);
383 *
384 * return current_number;
385 * }
386 * </programlisting>
387 * </example>
388 *
389 * It is easy to see that this won't work in a multi-threaded
390 * application. There current_number must be protected against shared
391 * access. A first naive implementation would be:
392 *
393 * <example>
394 * <title>The wrong way to write a thread-safe function</title>
395 * <programlisting>
396 * int
397 * give_me_next_number (void)
398 * {
399 * static int current_number = 0;
400 * int ret_val;
401 * static GMutex * mutex = NULL;
402 *
403 * if (!mutex) mutex = g_mutex_new (<!-- -->);
404 *
405 * g_mutex_lock (mutex);
406 * ret_val = current_number = calc_next_number (current_number);
407 * g_mutex_unlock (mutex);
408 *
409 * return ret_val;
410 * }
411 * </programlisting>
412 * </example>
413 *
414 * This looks like it would work, but there is a race condition while
415 * constructing the mutex and this code cannot work reliable. Please do
416 * not use such constructs in your own programs! One working solution
417 * is:
418 *
419 * <example>
420 * <title>A correct thread-safe function</title>
421 * <programlisting>
422 * static GMutex *give_me_next_number_mutex = NULL;
423 *
424 * /<!-- -->* this function must be called before any call to
425 * * give_me_next_number(<!-- -->)
426 * *
427 * * it must be called exactly once.
428 * *<!-- -->/
429 * void
430 * init_give_me_next_number (void)
431 * {
432 * g_assert (give_me_next_number_mutex == NULL);
433 * give_me_next_number_mutex = g_mutex_new (<!-- -->);
434 * }
435 *
436 * int
437 * give_me_next_number (void)
438 * {
439 * static int current_number = 0;
440 * int ret_val;
441 *
442 * g_mutex_lock (give_me_next_number_mutex);
443 * ret_val = current_number = calc_next_number (current_number);
444 * g_mutex_unlock (give_me_next_number_mutex);
445 *
446 * return ret_val;
447 * }
448 * </programlisting>
449 * </example>
450 *
451 * #GStaticMutex provides a simpler and safer way of doing this.
452 *
453 * If you want to use a mutex, and your code should also work without
454 * calling g_thread_init() first, then you cannot use a #GMutex, as
455 * g_mutex_new() requires that the thread system be initialized. Use a
456 * #GStaticMutex instead.
457 *
458 * A #GMutex should only be accessed via the following functions.
459 *
460 * <note><para>All of the <function>g_mutex_*</function> functions are
461 * actually macros. Apart from taking their addresses, you can however
462 * use them as if they were functions.</para></note>
463 **/
464
465 /**
466 * g_mutex_new:
467 * @Returns: a new #GMutex.
468 *
469 * Creates a new #GMutex.
470 *
471 * <note><para>This function will abort if g_thread_init() has not been
472 * called yet.</para></note>
473 **/
474 (GMutex*(*)())g_thread_fail,
475
476 /**
477 * g_mutex_lock:
478 * @mutex: a #GMutex.
479 *
480 * Locks @mutex. If @mutex is already locked by another thread, the
481 * current thread will block until @mutex is unlocked by the other
482 * thread.
483 *
484 * This function can be used even if g_thread_init() has not yet been
485 * called, and, in that case, will do nothing.
486 *
487 * <note><para>#GMutex is neither guaranteed to be recursive nor to be
488 * non-recursive, i.e. a thread could deadlock while calling
489 * g_mutex_lock(), if it already has locked @mutex. Use
490 * #GStaticRecMutex, if you need recursive mutexes.</para></note>
491 **/
492 NULL,
493
494 /**
495 * g_mutex_trylock:
496 * @mutex: a #GMutex.
497 * @Returns: %TRUE, if @mutex could be locked.
498 *
499 * Tries to lock @mutex. If @mutex is already locked by another thread,
500 * it immediately returns %FALSE. Otherwise it locks @mutex and returns
501 * %TRUE.
502 *
503 * This function can be used even if g_thread_init() has not yet been
504 * called, and, in that case, will immediately return %TRUE.
505 *
506 * <note><para>#GMutex is neither guaranteed to be recursive nor to be
507 * non-recursive, i.e. the return value of g_mutex_trylock() could be
508 * both %FALSE or %TRUE, if the current thread already has locked
509 * @mutex. Use #GStaticRecMutex, if you need recursive
510 * mutexes.</para></note>
511 **/
512 NULL,
513
514 /**
515 * g_mutex_unlock:
516 * @mutex: a #GMutex.
517 *
518 * Unlocks @mutex. If another thread is blocked in a g_mutex_lock()
519 * call for @mutex, it will be woken and can lock @mutex itself.
520 *
521 * This function can be used even if g_thread_init() has not yet been
522 * called, and, in that case, will do nothing.
523 **/
524 NULL,
525
526 /**
527 * g_mutex_free:
528 * @mutex: a #GMutex.
529 *
530 * Destroys @mutex.
531 *
532 * <note><para>Calling g_mutex_free() on a locked mutex may result in
533 * undefined behaviour.</para></note>
534 **/
535 NULL,
536
537 /* GCond Virtual Functions {{{2 ------------------------------------------ */
538
539 /**
540 * GCond:
541 *
542 * The #GCond struct is an opaque data structure that represents a
543 * condition. Threads can block on a #GCond if they find a certain
544 * condition to be false. If other threads change the state of this
545 * condition they signal the #GCond, and that causes the waiting
546 * threads to be woken up.
547 *
548 * <example>
549 * <title>
550 * Using GCond to block a thread until a condition is satisfied
551 * </title>
552 * <programlisting>
553 * GCond* data_cond = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
554 * GMutex* data_mutex = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
555 * gpointer current_data = NULL;
556 *
557 * void
558 * push_data (gpointer data)
559 * {
560 * g_mutex_lock (data_mutex);
561 * current_data = data;
562 * g_cond_signal (data_cond);
563 * g_mutex_unlock (data_mutex);
564 * }
565 *
566 * gpointer
567 * pop_data (void)
568 * {
569 * gpointer data;
570 *
571 * g_mutex_lock (data_mutex);
572 * while (!current_data)
573 * g_cond_wait (data_cond, data_mutex);
574 * data = current_data;
575 * current_data = NULL;
576 * g_mutex_unlock (data_mutex);
577 *
578 * return data;
579 * }
580 * </programlisting>
581 * </example>
582 *
583 * Whenever a thread calls <function>pop_data()</function> now, it will
584 * wait until current_data is non-%NULL, i.e. until some other thread
585 * has called <function>push_data()</function>.
586 *
587 * <note><para>It is important to use the g_cond_wait() and
588 * g_cond_timed_wait() functions only inside a loop which checks for the
589 * condition to be true. It is not guaranteed that the waiting thread
590 * will find the condition fulfilled after it wakes up, even if the
591 * signaling thread left the condition in that state: another thread may
592 * have altered the condition before the waiting thread got the chance
593 * to be woken up, even if the condition itself is protected by a
594 * #GMutex, like above.</para></note>
595 *
596 * A #GCond should only be accessed via the following functions.
597 *
598 * <note><para>All of the <function>g_cond_*</function> functions are
599 * actually macros. Apart from taking their addresses, you can however
600 * use them as if they were functions.</para></note>
601 **/
602
603 /**
604 * g_cond_new:
605 * @Returns: a new #GCond.
606 *
607 * Creates a new #GCond. This function will abort, if g_thread_init()
608 * has not been called yet.
609 **/
610 (GCond*(*)())g_thread_fail,
611
612 /**
613 * g_cond_signal:
614 * @cond: a #GCond.
615 *
616 * If threads are waiting for @cond, exactly one of them is woken up.
617 * It is good practice to hold the same lock as the waiting thread
618 * while calling this function, though not required.
619 *
620 * This function can be used even if g_thread_init() has not yet been
621 * called, and, in that case, will do nothing.
622 **/
623 NULL,
624
625 /**
626 * g_cond_broadcast:
627 * @cond: a #GCond.
628 *
629 * If threads are waiting for @cond, all of them are woken up. It is
630 * good practice to lock the same mutex as the waiting threads, while
631 * calling this function, though not required.
632 *
633 * This function can be used even if g_thread_init() has not yet been
634 * called, and, in that case, will do nothing.
635 **/
636 NULL,
637
638 /**
639 * g_cond_wait:
640 * @cond: a #GCond.
641 * @mutex: a #GMutex, that is currently locked.
642 *
643 * Waits until this thread is woken up on @cond. The @mutex is unlocked
644 * before falling asleep and locked again before resuming.
645 *
646 * This function can be used even if g_thread_init() has not yet been
647 * called, and, in that case, will immediately return.
648 **/
649 NULL,
650
651 /**
652 * g_cond_timed_wait:
653 * @cond: a #GCond.
654 * @mutex: a #GMutex that is currently locked.
655 * @abs_time: a #GTimeVal, determining the final time.
656 * @Returns: %TRUE if @cond was signalled, or %FALSE on timeout.
657 *
658 * Waits until this thread is woken up on @cond, but not longer than
659 * until the time specified by @abs_time. The @mutex is unlocked before
660 * falling asleep and locked again before resuming.
661 *
662 * If @abs_time is %NULL, g_cond_timed_wait() acts like g_cond_wait().
663 *
664 * This function can be used even if g_thread_init() has not yet been
665 * called, and, in that case, will immediately return %TRUE.
666 *
667 * To easily calculate @abs_time a combination of g_get_current_time()
668 * and g_time_val_add() can be used.
669 **/
670 NULL,
671
672 /**
673 * g_cond_free:
674 * @cond: a #GCond.
675 *
676 * Destroys the #GCond.
677 **/
678 NULL,
679
680 /* GPrivate Virtual Functions {{{2 --------------------------------------- */
681
682 /**
683 * GPrivate:
684 *
685 * <note><para>
686 * #GStaticPrivate is a better choice for most uses.
687 * </para></note>
688 *
689 * The #GPrivate struct is an opaque data structure to represent a
690 * thread private data key. Threads can thereby obtain and set a
691 * pointer which is private to the current thread. Take our
692 * <function>give_me_next_number(<!-- -->)</function> example from
693 * above. Suppose we don't want <literal>current_number</literal> to be
694 * shared between the threads, but instead to be private to each thread.
695 * This can be done as follows:
696 *
697 * <example>
698 * <title>Using GPrivate for per-thread data</title>
699 * <programlisting>
700 * GPrivate* current_number_key = NULL; /<!-- -->* Must be initialized somewhere
701 * with g_private_new (g_free); *<!-- -->/
702 *
703 * int
704 * give_me_next_number (void)
705 * {
706 * int *current_number = g_private_get (current_number_key);
707 *
708 * if (!current_number)
709 * {
710 * current_number = g_new (int, 1);
711 * *current_number = 0;
712 * g_private_set (current_number_key, current_number);
713 * }
714 *
715 * *current_number = calc_next_number (*current_number);
716 *
717 * return *current_number;
718 * }
719 * </programlisting>
720 * </example>
721 *
722 * Here the pointer belonging to the key
723 * <literal>current_number_key</literal> is read. If it is %NULL, it has
724 * not been set yet. Then get memory for an integer value, assign this
725 * memory to the pointer and write the pointer back. Now we have an
726 * integer value that is private to the current thread.
727 *
728 * The #GPrivate struct should only be accessed via the following
729 * functions.
730 *
731 * <note><para>All of the <function>g_private_*</function> functions are
732 * actually macros. Apart from taking their addresses, you can however
733 * use them as if they were functions.</para></note>
734 **/
735
736 /**
737 * g_private_new:
738 * @destructor: a function to destroy the data keyed to #GPrivate when
739 * a thread ends.
740 * @Returns: a new #GPrivate.
741 *
742 * Creates a new #GPrivate. If @destructor is non-%NULL, it is a
743 * pointer to a destructor function. Whenever a thread ends and the
744 * corresponding pointer keyed to this instance of #GPrivate is
745 * non-%NULL, the destructor is called with this pointer as the
746 * argument.
747 *
748 * <note><para>
749 * #GStaticPrivate is a better choice for most uses.
750 * </para></note>
751 *
752 * <note><para>@destructor is used quite differently from @notify in
753 * g_static_private_set().</para></note>
754 *
755 * <note><para>A #GPrivate cannot be freed. Reuse it instead, if you
756 * can, to avoid shortage, or use #GStaticPrivate.</para></note>
757 *
758 * <note><para>This function will abort if g_thread_init() has not been
759 * called yet.</para></note>
760 **/
761 (GPrivate*(*)(GDestroyNotify))g_thread_fail,
762
763 /**
764 * g_private_get:
765 * @private_key: a #GPrivate.
766 * @Returns: the corresponding pointer.
767 *
768 * Returns the pointer keyed to @private_key for the current thread. If
769 * g_private_set() hasn't been called for the current @private_key and
770 * thread yet, this pointer will be %NULL.
771 *
772 * This function can be used even if g_thread_init() has not yet been
773 * called, and, in that case, will return the value of @private_key
774 * casted to #gpointer. Note however, that private data set
775 * <emphasis>before</emphasis> g_thread_init() will
776 * <emphasis>not</emphasis> be retained <emphasis>after</emphasis> the
777 * call. Instead, %NULL will be returned in all threads directly after
778 * g_thread_init(), regardless of any g_private_set() calls issued
779 * before threading system intialization.
780 **/
781 NULL,
782
783 /**
784 * g_private_set:
785 * @private_key: a #GPrivate.
786 * @data: the new pointer.
787 *
788 * Sets the pointer keyed to @private_key for the current thread.
789 *
790 * This function can be used even if g_thread_init() has not yet been
791 * called, and, in that case, will set @private_key to @data casted to
792 * #GPrivate*. See g_private_get() for resulting caveats.
793 **/
794 NULL,
795
796 /* GThread Virtual Functions {{{2 ---------------------------------------- */
797 /**
798 * GThread:
799 *
800 * The #GThread struct represents a running thread. It has three public
801 * read-only members, but the underlying struct is bigger, so you must
802 * not copy this struct.
803 *
804 * <note><para>Resources for a joinable thread are not fully released
805 * until g_thread_join() is called for that thread.</para></note>
806 **/
807
808 /**
809 * GThreadFunc:
810 * @data: data passed to the thread.
811 * @Returns: the return value of the thread, which will be returned by
812 * g_thread_join().
813 *
814 * Specifies the type of the @func functions passed to
815 * g_thread_create() or g_thread_create_full().
816 **/
817
818 /**
819 * GThreadPriority:
820 * @G_THREAD_PRIORITY_LOW: a priority lower than normal
821 * @G_THREAD_PRIORITY_NORMAL: the default priority
822 * @G_THREAD_PRIORITY_HIGH: a priority higher than normal
823 * @G_THREAD_PRIORITY_URGENT: the highest priority
824 *
825 * Specifies the priority of a thread.
826 *
827 * <note><para>It is not guaranteed that threads with different priorities
828 * really behave accordingly. On some systems (e.g. Linux) there are no
829 * thread priorities. On other systems (e.g. Solaris) there doesn't
830 * seem to be different scheduling for different priorities. All in all
831 * try to avoid being dependent on priorities.</para></note>
832 **/
833
834 /**
835 * g_thread_create:
836 * @func: a function to execute in the new thread.
837 * @data: an argument to supply to the new thread.
838 * @joinable: should this thread be joinable?
839 * @error: return location for error.
840 * @Returns: the new #GThread on success.
841 *
842 * This function creates a new thread with the default priority.
843 *
844 * If @joinable is %TRUE, you can wait for this threads termination
845 * calling g_thread_join(). Otherwise the thread will just disappear
846 * when it terminates.
847 *
848 * The new thread executes the function @func with the argument @data.
849 * If the thread was created successfully, it is returned.
850 *
851 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
852 * The error is set, if and only if the function returns %NULL.
853 **/
854 (void(*)(GThreadFunc, gpointer, gulong,
855 gboolean, gboolean, GThreadPriority,
856 gpointer, GError**))g_thread_fail,
857
858 /**
859 * g_thread_yield:
860 *
861 * Gives way to other threads waiting to be scheduled.
862 *
863 * This function is often used as a method to make busy wait less evil.
864 * But in most cases you will encounter, there are better methods to do
865 * that. So in general you shouldn't use this function.
866 **/
867 NULL,
868
869 NULL, /* thread_join */
870 NULL, /* thread_exit */
871 NULL, /* thread_set_priority */
872 NULL, /* thread_self */
873 NULL /* thread_equal */
874 };
875
876 /* Local Data {{{1 -------------------------------------------------------- */
877
878 static GMutex *g_once_mutex = NULL;
879 static GCond *g_once_cond = NULL;
880 static GPrivate *g_thread_specific_private = NULL;
881 static GRealThread *g_thread_all_threads = NULL;
882 static GSList *g_thread_free_indices = NULL;
883 static GSList* g_once_init_list = NULL;
884
885 G_LOCK_DEFINE_STATIC (g_thread);
886
887 /* Initialisation {{{1 ---------------------------------------------------- */
888
889 #ifdef G_THREADS_ENABLED
890 /**
891 * g_thread_init:
892 * @vtable: a function table of type #GThreadFunctions, that provides
893 * the entry points to the thread system to be used.
894 *
895 * If you use GLib from more than one thread, you must initialize the
896 * thread system by calling g_thread_init(). Most of the time you will
897 * only have to call <literal>g_thread_init (NULL)</literal>.
898 *
899 * <note><para>Do not call g_thread_init() with a non-%NULL parameter unless
900 * you really know what you are doing.</para></note>
901 *
902 * <note><para>g_thread_init() must not be called directly or indirectly as a
903 * callback from GLib. Also no mutexes may be currently locked while
904 * calling g_thread_init().</para></note>
905 *
906 * <note><para>g_thread_init() changes the way in which #GTimer measures
907 * elapsed time. As a consequence, timers that are running while
908 * g_thread_init() is called may report unreliable times.</para></note>
909 *
910 * Calling g_thread_init() multiple times is allowed (since version
911 * 2.24), but nothing happens except for the first call. If the
912 * argument is non-%NULL on such a call a warning will be printed, but
913 * otherwise the argument is ignored.
914 *
915 * If no thread system is available and @vtable is %NULL or if not all
916 * elements of @vtable are non-%NULL, then g_thread_init() will abort.
917 *
918 * <note><para>To use g_thread_init() in your program, you have to link with
919 * the libraries that the command <command>pkg-config --libs
920 * gthread-2.0</command> outputs. This is not the case for all the
921 * other thread related functions of GLib. Those can be used without
922 * having to link with the thread libraries.</para></note>
923 **/
924
925 /* This must be called only once, before any threads are created.
926 * It will only be called from g_thread_init() in -lgthread.
927 */
928 void
g_thread_init_glib(void)929 g_thread_init_glib (void)
930 {
931 /* We let the main thread (the one that calls g_thread_init) inherit
932 * the static_private data set before calling g_thread_init
933 */
934 GRealThread* main_thread = (GRealThread*) g_thread_self ();
935
936 /* mutex and cond creation works without g_threads_got_initialized */
937 g_once_mutex = g_mutex_new ();
938 g_once_cond = g_cond_new ();
939
940 /* we may only create mutex and cond in here */
941 _g_mem_thread_init_noprivate_nomessage ();
942
943 /* setup the basic threading system */
944 g_threads_got_initialized = TRUE;
945 g_thread_specific_private = g_private_new (g_thread_cleanup);
946 g_private_set (g_thread_specific_private, main_thread);
947 G_THREAD_UF (thread_self, (&main_thread->system_thread));
948
949 /* complete memory system initialization, g_private_*() works now */
950 _g_slice_thread_init_nomessage ();
951
952 /* accomplish log system initialization to enable messaging */
953 _g_messages_thread_init_nomessage ();
954
955 /* we may run full-fledged initializers from here */
956 _g_utils_thread_init ();
957 _g_futex_thread_init ();
958 #ifdef G_OS_WIN32
959 _g_win32_thread_init ();
960 #endif
961 }
962 #endif /* G_THREADS_ENABLED */
963
964 /* The following sections implement: GOnce, GStaticMutex, GStaticRecMutex,
965 * GStaticPrivate,
966 **/
967
968 /* GOnce {{{1 ------------------------------------------------------------- */
969
970 /**
971 * GOnce:
972 * @status: the status of the #GOnce
973 * @retval: the value returned by the call to the function, if @status
974 * is %G_ONCE_STATUS_READY
975 *
976 * A #GOnce struct controls a one-time initialization function. Any
977 * one-time initialization function must have its own unique #GOnce
978 * struct.
979 *
980 * Since: 2.4
981 **/
982
983 /**
984 * G_ONCE_INIT:
985 *
986 * A #GOnce must be initialized with this macro before it can be used.
987 *
988 * <informalexample>
989 * <programlisting>
990 * GOnce my_once = G_ONCE_INIT;
991 * </programlisting>
992 * </informalexample>
993 *
994 * Since: 2.4
995 **/
996
997 /**
998 * GOnceStatus:
999 * @G_ONCE_STATUS_NOTCALLED: the function has not been called yet.
1000 * @G_ONCE_STATUS_PROGRESS: the function call is currently in progress.
1001 * @G_ONCE_STATUS_READY: the function has been called.
1002 *
1003 * The possible statuses of a one-time initialization function
1004 * controlled by a #GOnce struct.
1005 *
1006 * Since: 2.4
1007 **/
1008
1009 /**
1010 * g_once:
1011 * @once: a #GOnce structure
1012 * @func: the #GThreadFunc function associated to @once. This function
1013 * is called only once, regardless of the number of times it and
1014 * its associated #GOnce struct are passed to g_once().
1015 * @arg: data to be passed to @func
1016 *
1017 * The first call to this routine by a process with a given #GOnce
1018 * struct calls @func with the given argument. Thereafter, subsequent
1019 * calls to g_once() with the same #GOnce struct do not call @func
1020 * again, but return the stored result of the first call. On return
1021 * from g_once(), the status of @once will be %G_ONCE_STATUS_READY.
1022 *
1023 * For example, a mutex or a thread-specific data key must be created
1024 * exactly once. In a threaded environment, calling g_once() ensures
1025 * that the initialization is serialized across multiple threads.
1026 *
1027 * <note><para>Calling g_once() recursively on the same #GOnce struct in
1028 * @func will lead to a deadlock.</para></note>
1029 *
1030 * <informalexample>
1031 * <programlisting>
1032 * gpointer
1033 * get_debug_flags (void)
1034 * {
1035 * static GOnce my_once = G_ONCE_INIT;
1036 *
1037 * g_once (&my_once, parse_debug_flags, NULL);
1038 *
1039 * return my_once.retval;
1040 * }
1041 * </programlisting>
1042 * </informalexample>
1043 *
1044 * Since: 2.4
1045 **/
1046 gpointer
g_once_impl(GOnce * once,GThreadFunc func,gpointer arg)1047 g_once_impl (GOnce *once,
1048 GThreadFunc func,
1049 gpointer arg)
1050 {
1051 g_mutex_lock (g_once_mutex);
1052
1053 while (once->status == G_ONCE_STATUS_PROGRESS)
1054 g_cond_wait (g_once_cond, g_once_mutex);
1055
1056 if (once->status != G_ONCE_STATUS_READY)
1057 {
1058 once->status = G_ONCE_STATUS_PROGRESS;
1059 g_mutex_unlock (g_once_mutex);
1060
1061 once->retval = func (arg);
1062
1063 g_mutex_lock (g_once_mutex);
1064 once->status = G_ONCE_STATUS_READY;
1065 g_cond_broadcast (g_once_cond);
1066 }
1067
1068 g_mutex_unlock (g_once_mutex);
1069
1070 return once->retval;
1071 }
1072
1073 /**
1074 * g_once_init_enter:
1075 * @value_location: location of a static initializable variable
1076 * containing 0.
1077 * @Returns: %TRUE if the initialization section should be entered,
1078 * %FALSE and blocks otherwise
1079 *
1080 * Function to be called when starting a critical initialization
1081 * section. The argument @value_location must point to a static
1082 * 0-initialized variable that will be set to a value other than 0 at
1083 * the end of the initialization section. In combination with
1084 * g_once_init_leave() and the unique address @value_location, it can
1085 * be ensured that an initialization section will be executed only once
1086 * during a program's life time, and that concurrent threads are
1087 * blocked until initialization completed. To be used in constructs
1088 * like this:
1089 *
1090 * <informalexample>
1091 * <programlisting>
1092 * static gsize initialization_value = 0;
1093 *
1094 * if (g_once_init_enter (&initialization_value))
1095 * {
1096 * gsize setup_value = 42; /<!-- -->* initialization code here *<!-- -->/
1097 *
1098 * g_once_init_leave (&initialization_value, setup_value);
1099 * }
1100 *
1101 * /<!-- -->* use initialization_value here *<!-- -->/
1102 * </programlisting>
1103 * </informalexample>
1104 *
1105 * Since: 2.14
1106 **/
1107 gboolean
g_once_init_enter_impl(volatile gsize * value_location)1108 g_once_init_enter_impl (volatile gsize *value_location)
1109 {
1110 gboolean need_init = FALSE;
1111 g_mutex_lock (g_once_mutex);
1112 if (g_atomic_pointer_get (value_location) == NULL)
1113 {
1114 if (!g_slist_find (g_once_init_list, (void*) value_location))
1115 {
1116 need_init = TRUE;
1117 g_once_init_list = g_slist_prepend (g_once_init_list, (void*) value_location);
1118 }
1119 else
1120 do
1121 g_cond_wait (g_once_cond, g_once_mutex);
1122 while (g_slist_find (g_once_init_list, (void*) value_location));
1123 }
1124 g_mutex_unlock (g_once_mutex);
1125 return need_init;
1126 }
1127
1128 /**
1129 * g_once_init_leave:
1130 * @value_location: location of a static initializable variable
1131 * containing 0.
1132 * @initialization_value: new non-0 value for *@value_location.
1133 *
1134 * Counterpart to g_once_init_enter(). Expects a location of a static
1135 * 0-initialized initialization variable, and an initialization value
1136 * other than 0. Sets the variable to the initialization value, and
1137 * releases concurrent threads blocking in g_once_init_enter() on this
1138 * initialization variable.
1139 *
1140 * Since: 2.14
1141 **/
1142 void
g_once_init_leave(volatile gsize * value_location,gsize initialization_value)1143 g_once_init_leave (volatile gsize *value_location,
1144 gsize initialization_value)
1145 {
1146 g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
1147 g_return_if_fail (initialization_value != 0);
1148 g_return_if_fail (g_once_init_list != NULL);
1149
1150 g_atomic_pointer_set (value_location, initialization_value);
1151 g_mutex_lock (g_once_mutex);
1152 g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
1153 g_cond_broadcast (g_once_cond);
1154 g_mutex_unlock (g_once_mutex);
1155 }
1156
1157 /* GStaticMutex {{{1 ------------------------------------------------------ */
1158
1159 /**
1160 * GStaticMutex:
1161 *
1162 * A #GStaticMutex works like a #GMutex, but it has one significant
1163 * advantage. It doesn't need to be created at run-time like a #GMutex,
1164 * but can be defined at compile-time. Here is a shorter, easier and
1165 * safer version of our <function>give_me_next_number()</function>
1166 * example:
1167 *
1168 * <example>
1169 * <title>
1170 * Using <structname>GStaticMutex</structname>
1171 * to simplify thread-safe programming
1172 * </title>
1173 * <programlisting>
1174 * int
1175 * give_me_next_number (void)
1176 * {
1177 * static int current_number = 0;
1178 * int ret_val;
1179 * static GStaticMutex mutex = G_STATIC_MUTEX_INIT;
1180 *
1181 * g_static_mutex_lock (&mutex);
1182 * ret_val = current_number = calc_next_number (current_number);
1183 * g_static_mutex_unlock (&mutex);
1184 *
1185 * return ret_val;
1186 * }
1187 * </programlisting>
1188 * </example>
1189 *
1190 * Sometimes you would like to dynamically create a mutex. If you don't
1191 * want to require prior calling to g_thread_init(), because your code
1192 * should also be usable in non-threaded programs, you are not able to
1193 * use g_mutex_new() and thus #GMutex, as that requires a prior call to
1194 * g_thread_init(). In theses cases you can also use a #GStaticMutex.
1195 * It must be initialized with g_static_mutex_init() before using it
1196 * and freed with with g_static_mutex_free() when not needed anymore to
1197 * free up any allocated resources.
1198 *
1199 * Even though #GStaticMutex is not opaque, it should only be used with
1200 * the following functions, as it is defined differently on different
1201 * platforms.
1202 *
1203 * All of the <function>g_static_mutex_*</function> functions apart
1204 * from <function>g_static_mutex_get_mutex</function> can also be used
1205 * even if g_thread_init() has not yet been called. Then they do
1206 * nothing, apart from <function>g_static_mutex_trylock</function>,
1207 * which does nothing but returning %TRUE.
1208 *
1209 * <note><para>All of the <function>g_static_mutex_*</function>
1210 * functions are actually macros. Apart from taking their addresses, you
1211 * can however use them as if they were functions.</para></note>
1212 **/
1213
1214 /**
1215 * G_STATIC_MUTEX_INIT:
1216 *
1217 * A #GStaticMutex must be initialized with this macro, before it can
1218 * be used. This macro can used be to initialize a variable, but it
1219 * cannot be assigned to a variable. In that case you have to use
1220 * g_static_mutex_init().
1221 *
1222 * <informalexample>
1223 * <programlisting>
1224 * GStaticMutex my_mutex = G_STATIC_MUTEX_INIT;
1225 * </programlisting>
1226 * </informalexample>
1227 **/
1228
1229 /**
1230 * g_static_mutex_init:
1231 * @mutex: a #GStaticMutex to be initialized.
1232 *
1233 * Initializes @mutex. Alternatively you can initialize it with
1234 * #G_STATIC_MUTEX_INIT.
1235 **/
1236 void
g_static_mutex_init(GStaticMutex * mutex)1237 g_static_mutex_init (GStaticMutex *mutex)
1238 {
1239 static const GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
1240
1241 g_return_if_fail (mutex);
1242
1243 *mutex = init_mutex;
1244 }
1245
1246 /* IMPLEMENTATION NOTE:
1247 *
1248 * On some platforms a GStaticMutex is actually a normal GMutex stored
1249 * inside of a structure instead of being allocated dynamically. We can
1250 * only do this for platforms on which we know, in advance, how to
1251 * allocate (size) and initialise (value) that memory.
1252 *
1253 * On other platforms, a GStaticMutex is nothing more than a pointer to
1254 * a GMutex. In that case, the first access we make to the static mutex
1255 * must first allocate the normal GMutex and store it into the pointer.
1256 *
1257 * configure.ac writes macros into glibconfig.h to determine if
1258 * g_static_mutex_get_mutex() accesses the structure in memory directly
1259 * (on platforms where we are able to do that) or if it ends up here,
1260 * where we may have to allocate the GMutex before returning it.
1261 */
1262
1263 /**
1264 * g_static_mutex_get_mutex:
1265 * @mutex: a #GStaticMutex.
1266 * @Returns: the #GMutex corresponding to @mutex.
1267 *
1268 * For some operations (like g_cond_wait()) you must have a #GMutex
1269 * instead of a #GStaticMutex. This function will return the
1270 * corresponding #GMutex for @mutex.
1271 **/
1272 GMutex *
g_static_mutex_get_mutex_impl(GMutex ** mutex)1273 g_static_mutex_get_mutex_impl (GMutex** mutex)
1274 {
1275 GMutex *result;
1276
1277 if (!g_thread_supported ())
1278 return NULL;
1279
1280 result = g_atomic_pointer_get (mutex);
1281
1282 if (!result)
1283 {
1284 g_assert (g_once_mutex);
1285
1286 g_mutex_lock (g_once_mutex);
1287
1288 result = *mutex;
1289 if (!result)
1290 {
1291 result = g_mutex_new ();
1292 g_atomic_pointer_set (mutex, result);
1293 }
1294
1295 g_mutex_unlock (g_once_mutex);
1296 }
1297
1298 return result;
1299 }
1300
1301 /* IMPLEMENTATION NOTE:
1302 *
1303 * g_static_mutex_lock(), g_static_mutex_trylock() and
1304 * g_static_mutex_unlock() are all preprocessor macros that wrap the
1305 * corresponding g_mutex_*() function around a call to
1306 * g_static_mutex_get_mutex().
1307 */
1308
1309 /**
1310 * g_static_mutex_lock:
1311 * @mutex: a #GStaticMutex.
1312 *
1313 * Works like g_mutex_lock(), but for a #GStaticMutex.
1314 **/
1315
1316 /**
1317 * g_static_mutex_trylock:
1318 * @mutex: a #GStaticMutex.
1319 * @Returns: %TRUE, if the #GStaticMutex could be locked.
1320 *
1321 * Works like g_mutex_trylock(), but for a #GStaticMutex.
1322 **/
1323
1324 /**
1325 * g_static_mutex_unlock:
1326 * @mutex: a #GStaticMutex.
1327 *
1328 * Works like g_mutex_unlock(), but for a #GStaticMutex.
1329 **/
1330
1331 /**
1332 * g_static_mutex_free:
1333 * @mutex: a #GStaticMutex to be freed.
1334 *
1335 * Releases all resources allocated to @mutex.
1336 *
1337 * You don't have to call this functions for a #GStaticMutex with an
1338 * unbounded lifetime, i.e. objects declared 'static', but if you have
1339 * a #GStaticMutex as a member of a structure and the structure is
1340 * freed, you should also free the #GStaticMutex.
1341 *
1342 * <note><para>Calling g_static_mutex_free() on a locked mutex may
1343 * result in undefined behaviour.</para></note>
1344 **/
1345 void
g_static_mutex_free(GStaticMutex * mutex)1346 g_static_mutex_free (GStaticMutex* mutex)
1347 {
1348 GMutex **runtime_mutex;
1349
1350 g_return_if_fail (mutex);
1351
1352 /* The runtime_mutex is the first (or only) member of GStaticMutex,
1353 * see both versions (of glibconfig.h) in configure.ac. Note, that
1354 * this variable is NULL, if g_thread_init() hasn't been called or
1355 * if we're using the default thread implementation and it provides
1356 * static mutexes. */
1357 runtime_mutex = ((GMutex**)mutex);
1358
1359 if (*runtime_mutex)
1360 g_mutex_free (*runtime_mutex);
1361
1362 *runtime_mutex = NULL;
1363 }
1364
1365 /* ------------------------------------------------------------------------ */
1366
1367 /**
1368 * GStaticRecMutex:
1369 *
1370 * A #GStaticRecMutex works like a #GStaticMutex, but it can be locked
1371 * multiple times by one thread. If you enter it n times, you have to
1372 * unlock it n times again to let other threads lock it. An exception
1373 * is the function g_static_rec_mutex_unlock_full(): that allows you to
1374 * unlock a #GStaticRecMutex completely returning the depth, (i.e. the
1375 * number of times this mutex was locked). The depth can later be used
1376 * to restore the state of the #GStaticRecMutex by calling
1377 * g_static_rec_mutex_lock_full().
1378 *
1379 * Even though #GStaticRecMutex is not opaque, it should only be used
1380 * with the following functions.
1381 *
1382 * All of the <function>g_static_rec_mutex_*</function> functions can
1383 * be used even if g_thread_init() has not been called. Then they do
1384 * nothing, apart from <function>g_static_rec_mutex_trylock</function>,
1385 * which does nothing but returning %TRUE.
1386 **/
1387
1388 /**
1389 * G_STATIC_REC_MUTEX_INIT:
1390 *
1391 * A #GStaticRecMutex must be initialized with this macro before it can
1392 * be used. This macro can used be to initialize a variable, but it
1393 * cannot be assigned to a variable. In that case you have to use
1394 * g_static_rec_mutex_init().
1395 *
1396 * <informalexample>
1397 * <programlisting>
1398 * GStaticRecMutex my_mutex = G_STATIC_REC_MUTEX_INIT;
1399 * </programlisting>
1400 </informalexample>
1401 **/
1402
1403 /**
1404 * g_static_rec_mutex_init:
1405 * @mutex: a #GStaticRecMutex to be initialized.
1406 *
1407 * A #GStaticRecMutex must be initialized with this function before it
1408 * can be used. Alternatively you can initialize it with
1409 * #G_STATIC_REC_MUTEX_INIT.
1410 **/
1411 void
g_static_rec_mutex_init(GStaticRecMutex * mutex)1412 g_static_rec_mutex_init (GStaticRecMutex *mutex)
1413 {
1414 static const GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
1415
1416 g_return_if_fail (mutex);
1417
1418 *mutex = init_mutex;
1419 }
1420
1421 /**
1422 * g_static_rec_mutex_lock:
1423 * @mutex: a #GStaticRecMutex to lock.
1424 *
1425 * Locks @mutex. If @mutex is already locked by another thread, the
1426 * current thread will block until @mutex is unlocked by the other
1427 * thread. If @mutex is already locked by the calling thread, this
1428 * functions increases the depth of @mutex and returns immediately.
1429 **/
1430 void
g_static_rec_mutex_lock(GStaticRecMutex * mutex)1431 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
1432 {
1433 GSystemThread self;
1434
1435 g_return_if_fail (mutex);
1436
1437 if (!g_thread_supported ())
1438 return;
1439
1440 G_THREAD_UF (thread_self, (&self));
1441
1442 if (g_system_thread_equal (self, mutex->owner))
1443 {
1444 mutex->depth++;
1445 return;
1446 }
1447 g_static_mutex_lock (&mutex->mutex);
1448 g_system_thread_assign (mutex->owner, self);
1449 mutex->depth = 1;
1450 }
1451
1452 /**
1453 * g_static_rec_mutex_trylock:
1454 * @mutex: a #GStaticRecMutex to lock.
1455 * @Returns: %TRUE, if @mutex could be locked.
1456 *
1457 * Tries to lock @mutex. If @mutex is already locked by another thread,
1458 * it immediately returns %FALSE. Otherwise it locks @mutex and returns
1459 * %TRUE. If @mutex is already locked by the calling thread, this
1460 * functions increases the depth of @mutex and immediately returns
1461 * %TRUE.
1462 **/
1463 gboolean
g_static_rec_mutex_trylock(GStaticRecMutex * mutex)1464 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
1465 {
1466 GSystemThread self;
1467
1468 g_return_val_if_fail (mutex, FALSE);
1469
1470 if (!g_thread_supported ())
1471 return TRUE;
1472
1473 G_THREAD_UF (thread_self, (&self));
1474
1475 if (g_system_thread_equal (self, mutex->owner))
1476 {
1477 mutex->depth++;
1478 return TRUE;
1479 }
1480
1481 if (!g_static_mutex_trylock (&mutex->mutex))
1482 return FALSE;
1483
1484 g_system_thread_assign (mutex->owner, self);
1485 mutex->depth = 1;
1486 return TRUE;
1487 }
1488
1489 /**
1490 * g_static_rec_mutex_unlock:
1491 * @mutex: a #GStaticRecMutex to unlock.
1492 *
1493 * Unlocks @mutex. Another thread will be allowed to lock @mutex only
1494 * when it has been unlocked as many times as it had been locked
1495 * before. If @mutex is completely unlocked and another thread is
1496 * blocked in a g_static_rec_mutex_lock() call for @mutex, it will be
1497 * woken and can lock @mutex itself.
1498 **/
1499 void
g_static_rec_mutex_unlock(GStaticRecMutex * mutex)1500 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
1501 {
1502 g_return_if_fail (mutex);
1503
1504 if (!g_thread_supported ())
1505 return;
1506
1507 if (mutex->depth > 1)
1508 {
1509 mutex->depth--;
1510 return;
1511 }
1512 g_system_thread_assign (mutex->owner, zero_thread);
1513 g_static_mutex_unlock (&mutex->mutex);
1514 }
1515
1516 /**
1517 * g_static_rec_mutex_lock_full:
1518 * @mutex: a #GStaticRecMutex to lock.
1519 * @depth: number of times this mutex has to be unlocked to be
1520 * completely unlocked.
1521 *
1522 * Works like calling g_static_rec_mutex_lock() for @mutex @depth times.
1523 **/
1524 void
g_static_rec_mutex_lock_full(GStaticRecMutex * mutex,guint depth)1525 g_static_rec_mutex_lock_full (GStaticRecMutex *mutex,
1526 guint depth)
1527 {
1528 GSystemThread self;
1529 g_return_if_fail (mutex);
1530
1531 if (!g_thread_supported ())
1532 return;
1533
1534 if (depth == 0)
1535 return;
1536
1537 G_THREAD_UF (thread_self, (&self));
1538
1539 if (g_system_thread_equal (self, mutex->owner))
1540 {
1541 mutex->depth += depth;
1542 return;
1543 }
1544 g_static_mutex_lock (&mutex->mutex);
1545 g_system_thread_assign (mutex->owner, self);
1546 mutex->depth = depth;
1547 }
1548
1549 /**
1550 * g_static_rec_mutex_unlock_full:
1551 * @mutex: a #GStaticRecMutex to completely unlock.
1552 * @Returns: number of times @mutex has been locked by the current
1553 * thread.
1554 *
1555 * Completely unlocks @mutex. If another thread is blocked in a
1556 * g_static_rec_mutex_lock() call for @mutex, it will be woken and can
1557 * lock @mutex itself. This function returns the number of times that
1558 * @mutex has been locked by the current thread. To restore the state
1559 * before the call to g_static_rec_mutex_unlock_full() you can call
1560 * g_static_rec_mutex_lock_full() with the depth returned by this
1561 * function.
1562 **/
1563 guint
g_static_rec_mutex_unlock_full(GStaticRecMutex * mutex)1564 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
1565 {
1566 guint depth;
1567
1568 g_return_val_if_fail (mutex, 0);
1569
1570 if (!g_thread_supported ())
1571 return 1;
1572
1573 depth = mutex->depth;
1574
1575 g_system_thread_assign (mutex->owner, zero_thread);
1576 mutex->depth = 0;
1577 g_static_mutex_unlock (&mutex->mutex);
1578
1579 return depth;
1580 }
1581
1582 /**
1583 * g_static_rec_mutex_free:
1584 * @mutex: a #GStaticRecMutex to be freed.
1585 *
1586 * Releases all resources allocated to a #GStaticRecMutex.
1587 *
1588 * You don't have to call this functions for a #GStaticRecMutex with an
1589 * unbounded lifetime, i.e. objects declared 'static', but if you have
1590 * a #GStaticRecMutex as a member of a structure and the structure is
1591 * freed, you should also free the #GStaticRecMutex.
1592 **/
1593 void
g_static_rec_mutex_free(GStaticRecMutex * mutex)1594 g_static_rec_mutex_free (GStaticRecMutex *mutex)
1595 {
1596 g_return_if_fail (mutex);
1597
1598 g_static_mutex_free (&mutex->mutex);
1599 }
1600
1601 /* GStaticPrivate {{{1 ---------------------------------------------------- */
1602
1603 /**
1604 * GStaticPrivate:
1605 *
1606 * A #GStaticPrivate works almost like a #GPrivate, but it has one
1607 * significant advantage. It doesn't need to be created at run-time
1608 * like a #GPrivate, but can be defined at compile-time. This is
1609 * similar to the difference between #GMutex and #GStaticMutex. Now
1610 * look at our <function>give_me_next_number()</function> example with
1611 * #GStaticPrivate:
1612 *
1613 * <example>
1614 * <title>Using GStaticPrivate for per-thread data</title>
1615 * <programlisting>
1616 * int
1617 * give_me_next_number (<!-- -->)
1618 * {
1619 * static GStaticPrivate current_number_key = G_STATIC_PRIVATE_INIT;
1620 * int *current_number = g_static_private_get (&current_number_key);
1621 *
1622 * if (!current_number)
1623 * {
1624 * current_number = g_new (int,1);
1625 * *current_number = 0;
1626 * g_static_private_set (&current_number_key, current_number, g_free);
1627 * }
1628 *
1629 * *current_number = calc_next_number (*current_number);
1630 *
1631 * return *current_number;
1632 * }
1633 * </programlisting>
1634 * </example>
1635 **/
1636
1637 /**
1638 * G_STATIC_PRIVATE_INIT:
1639 *
1640 * Every #GStaticPrivate must be initialized with this macro, before it
1641 * can be used.
1642 *
1643 * <informalexample>
1644 * <programlisting>
1645 * GStaticPrivate my_private = G_STATIC_PRIVATE_INIT;
1646 * </programlisting>
1647 * </informalexample>
1648 **/
1649
1650 /**
1651 * g_static_private_init:
1652 * @private_key: a #GStaticPrivate to be initialized.
1653 *
1654 * Initializes @private_key. Alternatively you can initialize it with
1655 * #G_STATIC_PRIVATE_INIT.
1656 **/
1657 void
g_static_private_init(GStaticPrivate * private_key)1658 g_static_private_init (GStaticPrivate *private_key)
1659 {
1660 private_key->index = 0;
1661 }
1662
1663 /**
1664 * g_static_private_get:
1665 * @private_key: a #GStaticPrivate.
1666 * @Returns: the corresponding pointer.
1667 *
1668 * Works like g_private_get() only for a #GStaticPrivate.
1669 *
1670 * This function works even if g_thread_init() has not yet been called.
1671 **/
1672 gpointer
g_static_private_get(GStaticPrivate * private_key)1673 g_static_private_get (GStaticPrivate *private_key)
1674 {
1675 GRealThread *self = (GRealThread*) g_thread_self ();
1676 GArray *array;
1677 gpointer ret = NULL;
1678
1679 LOCK_PRIVATE_DATA (self);
1680
1681 array = self->private_data;
1682
1683 if (array && private_key->index != 0 && private_key->index <= array->len)
1684 ret = g_array_index (array, GStaticPrivateNode,
1685 private_key->index - 1).data;
1686
1687 UNLOCK_PRIVATE_DATA (self);
1688 return ret;
1689 }
1690
1691 /**
1692 * g_static_private_set:
1693 * @private_key: a #GStaticPrivate.
1694 * @data: the new pointer.
1695 * @notify: a function to be called with the pointer whenever the
1696 * current thread ends or sets this pointer again.
1697 *
1698 * Sets the pointer keyed to @private_key for the current thread and
1699 * the function @notify to be called with that pointer (%NULL or
1700 * non-%NULL), whenever the pointer is set again or whenever the
1701 * current thread ends.
1702 *
1703 * This function works even if g_thread_init() has not yet been called.
1704 * If g_thread_init() is called later, the @data keyed to @private_key
1705 * will be inherited only by the main thread, i.e. the one that called
1706 * g_thread_init().
1707 *
1708 * <note><para>@notify is used quite differently from @destructor in
1709 * g_private_new().</para></note>
1710 **/
1711 void
g_static_private_set(GStaticPrivate * private_key,gpointer data,GDestroyNotify notify)1712 g_static_private_set (GStaticPrivate *private_key,
1713 gpointer data,
1714 GDestroyNotify notify)
1715 {
1716 GRealThread *self = (GRealThread*) g_thread_self ();
1717 GArray *array;
1718 static guint next_index = 0;
1719 GStaticPrivateNode *node;
1720 gpointer ddata = NULL;
1721 GDestroyNotify ddestroy = NULL;
1722
1723 if (!private_key->index)
1724 {
1725 G_LOCK (g_thread);
1726
1727 if (!private_key->index)
1728 {
1729 if (g_thread_free_indices)
1730 {
1731 private_key->index =
1732 GPOINTER_TO_UINT (g_thread_free_indices->data);
1733 g_thread_free_indices =
1734 g_slist_delete_link (g_thread_free_indices,
1735 g_thread_free_indices);
1736 }
1737 else
1738 private_key->index = ++next_index;
1739 }
1740
1741 G_UNLOCK (g_thread);
1742 }
1743
1744 LOCK_PRIVATE_DATA (self);
1745
1746 array = self->private_data;
1747 if (!array)
1748 {
1749 array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
1750 self->private_data = array;
1751 }
1752
1753 if (private_key->index > array->len)
1754 g_array_set_size (array, private_key->index);
1755
1756 node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
1757
1758 ddata = node->data;
1759 ddestroy = node->destroy;
1760
1761 node->data = data;
1762 node->destroy = notify;
1763
1764 UNLOCK_PRIVATE_DATA (self);
1765
1766 if (ddestroy)
1767 ddestroy (ddata);
1768 }
1769
1770 /**
1771 * g_static_private_free:
1772 * @private_key: a #GStaticPrivate to be freed.
1773 *
1774 * Releases all resources allocated to @private_key.
1775 *
1776 * You don't have to call this functions for a #GStaticPrivate with an
1777 * unbounded lifetime, i.e. objects declared 'static', but if you have
1778 * a #GStaticPrivate as a member of a structure and the structure is
1779 * freed, you should also free the #GStaticPrivate.
1780 **/
1781 void
g_static_private_free(GStaticPrivate * private_key)1782 g_static_private_free (GStaticPrivate *private_key)
1783 {
1784 guint idx = private_key->index;
1785 GRealThread *thread, *next;
1786 GArray *garbage = NULL;
1787
1788 if (!idx)
1789 return;
1790
1791 private_key->index = 0;
1792
1793 G_LOCK (g_thread);
1794
1795 thread = g_thread_all_threads;
1796
1797 for (thread = g_thread_all_threads; thread; thread = next)
1798 {
1799 GArray *array;
1800
1801 next = thread->next;
1802
1803 LOCK_PRIVATE_DATA (thread);
1804
1805 array = thread->private_data;
1806
1807 if (array && idx <= array->len)
1808 {
1809 GStaticPrivateNode *node = &g_array_index (array,
1810 GStaticPrivateNode,
1811 idx - 1);
1812 gpointer ddata = node->data;
1813 GDestroyNotify ddestroy = node->destroy;
1814
1815 node->data = NULL;
1816 node->destroy = NULL;
1817
1818 if (ddestroy)
1819 {
1820 /* defer non-trivial destruction til after we've finished
1821 * iterating, since we must continue to hold the lock */
1822 if (garbage == NULL)
1823 garbage = g_array_new (FALSE, TRUE,
1824 sizeof (GStaticPrivateNode));
1825
1826 g_array_set_size (garbage, garbage->len + 1);
1827
1828 node = &g_array_index (garbage, GStaticPrivateNode,
1829 garbage->len - 1);
1830 node->data = ddata;
1831 node->destroy = ddestroy;
1832 }
1833 }
1834
1835 UNLOCK_PRIVATE_DATA (thread);
1836 }
1837 g_thread_free_indices = g_slist_prepend (g_thread_free_indices,
1838 GUINT_TO_POINTER (idx));
1839 G_UNLOCK (g_thread);
1840
1841 if (garbage)
1842 {
1843 guint i;
1844
1845 for (i = 0; i < garbage->len; i++)
1846 {
1847 GStaticPrivateNode *node;
1848
1849 node = &g_array_index (garbage, GStaticPrivateNode, i);
1850 node->destroy (node->data);
1851 }
1852
1853 g_array_free (garbage, TRUE);
1854 }
1855 }
1856
1857 /* GThread Extra Functions {{{1 ------------------------------------------- */
1858 static void
g_thread_cleanup(gpointer data)1859 g_thread_cleanup (gpointer data)
1860 {
1861 if (data)
1862 {
1863 GRealThread* thread = data;
1864 GArray *array;
1865
1866 LOCK_PRIVATE_DATA (thread);
1867 array = thread->private_data;
1868 thread->private_data = NULL;
1869 UNLOCK_PRIVATE_DATA (thread);
1870
1871 if (array)
1872 {
1873 guint i;
1874
1875 for (i = 0; i < array->len; i++ )
1876 {
1877 GStaticPrivateNode *node =
1878 &g_array_index (array, GStaticPrivateNode, i);
1879 if (node->destroy)
1880 node->destroy (node->data);
1881 }
1882 g_array_free (array, TRUE);
1883 }
1884
1885 /* We only free the thread structure, if it isn't joinable. If
1886 it is, the structure is freed in g_thread_join */
1887 if (!thread->thread.joinable)
1888 {
1889 GRealThread *t, *p;
1890
1891 G_LOCK (g_thread);
1892 for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
1893 {
1894 if (t == thread)
1895 {
1896 if (p)
1897 p->next = t->next;
1898 else
1899 g_thread_all_threads = t->next;
1900 break;
1901 }
1902 }
1903 G_UNLOCK (g_thread);
1904
1905 /* Just to make sure, this isn't used any more */
1906 g_system_thread_assign (thread->system_thread, zero_thread);
1907 g_free (thread);
1908 }
1909 }
1910 }
1911
1912 static void
g_thread_fail(void)1913 g_thread_fail (void)
1914 {
1915 g_error ("The thread system is not yet initialized.");
1916 }
1917
1918 #define G_NSEC_PER_SEC 1000000000
1919 #define G_USEC_PER_SEC 1000000
1920
1921 static guint64
gettime(void)1922 gettime (void)
1923 {
1924 #ifdef G_OS_WIN32
1925 guint64 v;
1926
1927 /* Returns 100s of nanoseconds since start of 1601 */
1928 GetSystemTimeAsFileTime ((FILETIME *)&v);
1929
1930 /* Offset to Unix epoch */
1931 v -= G_GINT64_CONSTANT (116444736000000000);
1932 /* Convert to nanoseconds */
1933 v *= 100;
1934
1935 return v;
1936 #else
1937 struct timeval tv;
1938
1939 gettimeofday (&tv, NULL);
1940
1941 return (guint64) tv.tv_sec * G_NSEC_PER_SEC + tv.tv_usec * (G_NSEC_PER_SEC / G_USEC_PER_SEC);
1942 #endif
1943 }
1944
1945 static gpointer
g_thread_create_proxy(gpointer data)1946 g_thread_create_proxy (gpointer data)
1947 {
1948 GRealThread* thread = data;
1949
1950 g_assert (data);
1951
1952 /* This has to happen before G_LOCK, as that might call g_thread_self */
1953 g_private_set (g_thread_specific_private, data);
1954
1955 /* the lock makes sure, that thread->system_thread is written,
1956 before thread->thread.func is called. See g_thread_create. */
1957 G_LOCK (g_thread);
1958 G_UNLOCK (g_thread);
1959
1960 thread->retval = thread->thread.func (thread->thread.data);
1961
1962 return NULL;
1963 }
1964
1965 /**
1966 * g_thread_create_full:
1967 * @func: a function to execute in the new thread.
1968 * @data: an argument to supply to the new thread.
1969 * @stack_size: a stack size for the new thread.
1970 * @joinable: should this thread be joinable?
1971 * @bound: should this thread be bound to a system thread?
1972 * @priority: a priority for the thread.
1973 * @error: return location for error.
1974 * @Returns: the new #GThread on success.
1975 *
1976 * This function creates a new thread with the priority @priority. If
1977 * the underlying thread implementation supports it, the thread gets a
1978 * stack size of @stack_size or the default value for the current
1979 * platform, if @stack_size is 0.
1980 *
1981 * If @joinable is %TRUE, you can wait for this threads termination
1982 * calling g_thread_join(). Otherwise the thread will just disappear
1983 * when it terminates. If @bound is %TRUE, this thread will be
1984 * scheduled in the system scope, otherwise the implementation is free
1985 * to do scheduling in the process scope. The first variant is more
1986 * expensive resource-wise, but generally faster. On some systems (e.g.
1987 * Linux) all threads are bound.
1988 *
1989 * The new thread executes the function @func with the argument @data.
1990 * If the thread was created successfully, it is returned.
1991 *
1992 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
1993 * The error is set, if and only if the function returns %NULL.
1994 *
1995 * <note><para>It is not guaranteed that threads with different priorities
1996 * really behave accordingly. On some systems (e.g. Linux) there are no
1997 * thread priorities. On other systems (e.g. Solaris) there doesn't
1998 * seem to be different scheduling for different priorities. All in all
1999 * try to avoid being dependent on priorities. Use
2000 * %G_THREAD_PRIORITY_NORMAL here as a default.</para></note>
2001 *
2002 * <note><para>Only use g_thread_create_full() if you really can't use
2003 * g_thread_create() instead. g_thread_create() does not take
2004 * @stack_size, @bound, and @priority as arguments, as they should only
2005 * be used in cases in which it is unavoidable.</para></note>
2006 **/
2007 GThread*
g_thread_create_full(GThreadFunc func,gpointer data,gulong stack_size,gboolean joinable,gboolean bound,GThreadPriority priority,GError ** error)2008 g_thread_create_full (GThreadFunc func,
2009 gpointer data,
2010 gulong stack_size,
2011 gboolean joinable,
2012 gboolean bound,
2013 GThreadPriority priority,
2014 GError **error)
2015 {
2016 GRealThread* result;
2017 GError *local_error = NULL;
2018 g_return_val_if_fail (func, NULL);
2019 g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
2020 g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
2021
2022 result = g_new0 (GRealThread, 1);
2023
2024 result->thread.joinable = joinable;
2025 result->thread.priority = priority;
2026 result->thread.func = func;
2027 result->thread.data = data;
2028 result->private_data = NULL;
2029 G_LOCK (g_thread);
2030 G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
2031 stack_size, joinable, bound, priority,
2032 &result->system_thread, &local_error));
2033 if (!local_error)
2034 {
2035 result->next = g_thread_all_threads;
2036 g_thread_all_threads = result;
2037 }
2038 G_UNLOCK (g_thread);
2039
2040 if (local_error)
2041 {
2042 g_propagate_error (error, local_error);
2043 g_free (result);
2044 return NULL;
2045 }
2046
2047 return (GThread*) result;
2048 }
2049
2050 /**
2051 * g_thread_exit:
2052 * @retval: the return value of this thread.
2053 *
2054 * Exits the current thread. If another thread is waiting for that
2055 * thread using g_thread_join() and the current thread is joinable, the
2056 * waiting thread will be woken up and get @retval as the return value
2057 * of g_thread_join(). If the current thread is not joinable, @retval
2058 * is ignored. Calling
2059 *
2060 * <informalexample>
2061 * <programlisting>
2062 * g_thread_exit (retval);
2063 * </programlisting>
2064 * </informalexample>
2065 *
2066 * is equivalent to returning @retval from the function @func, as given
2067 * to g_thread_create().
2068 *
2069 * <note><para>Never call g_thread_exit() from within a thread of a
2070 * #GThreadPool, as that will mess up the bookkeeping and lead to funny
2071 * and unwanted results.</para></note>
2072 **/
2073 void
g_thread_exit(gpointer retval)2074 g_thread_exit (gpointer retval)
2075 {
2076 GRealThread* real = (GRealThread*) g_thread_self ();
2077 real->retval = retval;
2078 G_THREAD_CF (thread_exit, (void)0, ());
2079 }
2080
2081 /**
2082 * g_thread_join:
2083 * @thread: a #GThread to be waited for.
2084 * @Returns: the return value of the thread.
2085 *
2086 * Waits until @thread finishes, i.e. the function @func, as given to
2087 * g_thread_create(), returns or g_thread_exit() is called by @thread.
2088 * All resources of @thread including the #GThread struct are released.
2089 * @thread must have been created with @joinable=%TRUE in
2090 * g_thread_create(). The value returned by @func or given to
2091 * g_thread_exit() by @thread is returned by this function.
2092 **/
2093 gpointer
g_thread_join(GThread * thread)2094 g_thread_join (GThread* thread)
2095 {
2096 GRealThread* real = (GRealThread*) thread;
2097 GRealThread *p, *t;
2098 gpointer retval;
2099
2100 g_return_val_if_fail (thread, NULL);
2101 g_return_val_if_fail (thread->joinable, NULL);
2102 g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
2103 zero_thread), NULL);
2104
2105 G_THREAD_UF (thread_join, (&real->system_thread));
2106
2107 retval = real->retval;
2108
2109 G_LOCK (g_thread);
2110 for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
2111 {
2112 if (t == (GRealThread*) thread)
2113 {
2114 if (p)
2115 p->next = t->next;
2116 else
2117 g_thread_all_threads = t->next;
2118 break;
2119 }
2120 }
2121 G_UNLOCK (g_thread);
2122
2123 /* Just to make sure, this isn't used any more */
2124 thread->joinable = 0;
2125 g_system_thread_assign (real->system_thread, zero_thread);
2126
2127 /* the thread structure for non-joinable threads is freed upon
2128 thread end. We free the memory here. This will leave a loose end,
2129 if a joinable thread is not joined. */
2130
2131 g_free (thread);
2132
2133 return retval;
2134 }
2135
2136 /**
2137 * g_thread_set_priority:
2138 * @thread: a #GThread.
2139 * @priority: a new priority for @thread.
2140 *
2141 * Changes the priority of @thread to @priority.
2142 *
2143 * <note><para>It is not guaranteed that threads with different
2144 * priorities really behave accordingly. On some systems (e.g. Linux)
2145 * there are no thread priorities. On other systems (e.g. Solaris) there
2146 * doesn't seem to be different scheduling for different priorities. All
2147 * in all try to avoid being dependent on priorities.</para></note>
2148 **/
2149 void
g_thread_set_priority(GThread * thread,GThreadPriority priority)2150 g_thread_set_priority (GThread* thread,
2151 GThreadPriority priority)
2152 {
2153 GRealThread* real = (GRealThread*) thread;
2154
2155 g_return_if_fail (thread);
2156 g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
2157 g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
2158 g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
2159
2160 thread->priority = priority;
2161
2162 G_THREAD_CF (thread_set_priority, (void)0,
2163 (&real->system_thread, priority));
2164 }
2165
2166 /**
2167 * g_thread_self:
2168 * @Returns: the current thread.
2169 *
2170 * This functions returns the #GThread corresponding to the calling
2171 * thread.
2172 **/
2173 GThread*
g_thread_self(void)2174 g_thread_self (void)
2175 {
2176 GRealThread* thread = g_private_get (g_thread_specific_private);
2177
2178 if (!thread)
2179 {
2180 /* If no thread data is available, provide and set one. This
2181 can happen for the main thread and for threads, that are not
2182 created by GLib. */
2183 thread = g_new0 (GRealThread, 1);
2184 thread->thread.joinable = FALSE; /* This is a save guess */
2185 thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
2186 just a guess */
2187 thread->thread.func = NULL;
2188 thread->thread.data = NULL;
2189 thread->private_data = NULL;
2190
2191 if (g_thread_supported ())
2192 G_THREAD_UF (thread_self, (&thread->system_thread));
2193
2194 g_private_set (g_thread_specific_private, thread);
2195
2196 G_LOCK (g_thread);
2197 thread->next = g_thread_all_threads;
2198 g_thread_all_threads = thread;
2199 G_UNLOCK (g_thread);
2200 }
2201
2202 return (GThread*)thread;
2203 }
2204
2205 /* GStaticRWLock {{{1 ----------------------------------------------------- */
2206
2207 /**
2208 * GStaticRWLock:
2209 *
2210 * The #GStaticRWLock struct represents a read-write lock. A read-write
2211 * lock can be used for protecting data that some portions of code only
2212 * read from, while others also write. In such situations it is
2213 * desirable that several readers can read at once, whereas of course
2214 * only one writer may write at a time. Take a look at the following
2215 * example:
2216 *
2217 * <example>
2218 * <title>An array with access functions</title>
2219 * <programlisting>
2220 * GStaticRWLock rwlock = G_STATIC_RW_LOCK_INIT;
2221 * GPtrArray *array;
2222 *
2223 * gpointer
2224 * my_array_get (guint index)
2225 * {
2226 * gpointer retval = NULL;
2227 *
2228 * if (!array)
2229 * return NULL;
2230 *
2231 * g_static_rw_lock_reader_lock (&rwlock);
2232 * if (index < array->len)
2233 * retval = g_ptr_array_index (array, index);
2234 * g_static_rw_lock_reader_unlock (&rwlock);
2235 *
2236 * return retval;
2237 * }
2238 *
2239 * void
2240 * my_array_set (guint index, gpointer data)
2241 * {
2242 * g_static_rw_lock_writer_lock (&rwlock);
2243 *
2244 * if (!array)
2245 * array = g_ptr_array_new (<!-- -->);
2246 *
2247 * if (index >= array->len)
2248 * g_ptr_array_set_size (array, index+1);
2249 * g_ptr_array_index (array, index) = data;
2250 *
2251 * g_static_rw_lock_writer_unlock (&rwlock);
2252 * }
2253 * </programlisting>
2254 * </example>
2255 *
2256 * This example shows an array which can be accessed by many readers
2257 * (the <function>my_array_get()</function> function) simultaneously,
2258 * whereas the writers (the <function>my_array_set()</function>
2259 * function) will only be allowed once at a time and only if no readers
2260 * currently access the array. This is because of the potentially
2261 * dangerous resizing of the array. Using these functions is fully
2262 * multi-thread safe now.
2263 *
2264 * Most of the time, writers should have precedence over readers. That
2265 * means, for this implementation, that as soon as a writer wants to
2266 * lock the data, no other reader is allowed to lock the data, whereas,
2267 * of course, the readers that already have locked the data are allowed
2268 * to finish their operation. As soon as the last reader unlocks the
2269 * data, the writer will lock it.
2270 *
2271 * Even though #GStaticRWLock is not opaque, it should only be used
2272 * with the following functions.
2273 *
2274 * All of the <function>g_static_rw_lock_*</function> functions can be
2275 * used even if g_thread_init() has not been called. Then they do
2276 * nothing, apart from <function>g_static_rw_lock_*_trylock</function>,
2277 * which does nothing but returning %TRUE.
2278 *
2279 * <note><para>A read-write lock has a higher overhead than a mutex. For
2280 * example, both g_static_rw_lock_reader_lock() and
2281 * g_static_rw_lock_reader_unlock() have to lock and unlock a
2282 * #GStaticMutex, so it takes at least twice the time to lock and unlock
2283 * a #GStaticRWLock that it does to lock and unlock a #GStaticMutex. So
2284 * only data structures that are accessed by multiple readers, and which
2285 * keep the lock for a considerable time justify a #GStaticRWLock. The
2286 * above example most probably would fare better with a
2287 * #GStaticMutex.</para></note>
2288 **/
2289
2290 /**
2291 * G_STATIC_RW_LOCK_INIT:
2292 *
2293 * A #GStaticRWLock must be initialized with this macro before it can
2294 * be used. This macro can used be to initialize a variable, but it
2295 * cannot be assigned to a variable. In that case you have to use
2296 * g_static_rw_lock_init().
2297 *
2298 * <informalexample>
2299 * <programlisting>
2300 * GStaticRWLock my_lock = G_STATIC_RW_LOCK_INIT;
2301 * </programlisting>
2302 * </informalexample>
2303 **/
2304
2305 /**
2306 * g_static_rw_lock_init:
2307 * @lock: a #GStaticRWLock to be initialized.
2308 *
2309 * A #GStaticRWLock must be initialized with this function before it
2310 * can be used. Alternatively you can initialize it with
2311 * #G_STATIC_RW_LOCK_INIT.
2312 **/
2313 void
g_static_rw_lock_init(GStaticRWLock * lock)2314 g_static_rw_lock_init (GStaticRWLock* lock)
2315 {
2316 static const GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
2317
2318 g_return_if_fail (lock);
2319
2320 *lock = init_lock;
2321 }
2322
2323 inline static void
g_static_rw_lock_wait(GCond ** cond,GStaticMutex * mutex)2324 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
2325 {
2326 if (!*cond)
2327 *cond = g_cond_new ();
2328 g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
2329 }
2330
2331 inline static void
g_static_rw_lock_signal(GStaticRWLock * lock)2332 g_static_rw_lock_signal (GStaticRWLock* lock)
2333 {
2334 if (lock->want_to_write && lock->write_cond)
2335 g_cond_signal (lock->write_cond);
2336 else if (lock->want_to_read && lock->read_cond)
2337 g_cond_broadcast (lock->read_cond);
2338 }
2339
2340 /**
2341 * g_static_rw_lock_reader_lock:
2342 * @lock: a #GStaticRWLock to lock for reading.
2343 *
2344 * Locks @lock for reading. There may be unlimited concurrent locks for
2345 * reading of a #GStaticRWLock at the same time. If @lock is already
2346 * locked for writing by another thread or if another thread is already
2347 * waiting to lock @lock for writing, this function will block until
2348 * @lock is unlocked by the other writing thread and no other writing
2349 * threads want to lock @lock. This lock has to be unlocked by
2350 * g_static_rw_lock_reader_unlock().
2351 *
2352 * #GStaticRWLock is not recursive. It might seem to be possible to
2353 * recursively lock for reading, but that can result in a deadlock, due
2354 * to writer preference.
2355 **/
2356 void
g_static_rw_lock_reader_lock(GStaticRWLock * lock)2357 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
2358 {
2359 g_return_if_fail (lock);
2360
2361 if (!g_threads_got_initialized)
2362 return;
2363
2364 g_static_mutex_lock (&lock->mutex);
2365 lock->want_to_read++;
2366 while (lock->have_writer || lock->want_to_write)
2367 g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
2368 lock->want_to_read--;
2369 lock->read_counter++;
2370 g_static_mutex_unlock (&lock->mutex);
2371 }
2372
2373 /**
2374 * g_static_rw_lock_reader_trylock:
2375 * @lock: a #GStaticRWLock to lock for reading.
2376 * @Returns: %TRUE, if @lock could be locked for reading.
2377 *
2378 * Tries to lock @lock for reading. If @lock is already locked for
2379 * writing by another thread or if another thread is already waiting to
2380 * lock @lock for writing, immediately returns %FALSE. Otherwise locks
2381 * @lock for reading and returns %TRUE. This lock has to be unlocked by
2382 * g_static_rw_lock_reader_unlock().
2383 **/
2384 gboolean
g_static_rw_lock_reader_trylock(GStaticRWLock * lock)2385 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
2386 {
2387 gboolean ret_val = FALSE;
2388
2389 g_return_val_if_fail (lock, FALSE);
2390
2391 if (!g_threads_got_initialized)
2392 return TRUE;
2393
2394 g_static_mutex_lock (&lock->mutex);
2395 if (!lock->have_writer && !lock->want_to_write)
2396 {
2397 lock->read_counter++;
2398 ret_val = TRUE;
2399 }
2400 g_static_mutex_unlock (&lock->mutex);
2401 return ret_val;
2402 }
2403
2404 /**
2405 * g_static_rw_lock_reader_unlock:
2406 * @lock: a #GStaticRWLock to unlock after reading.
2407 *
2408 * Unlocks @lock. If a thread waits to lock @lock for writing and all
2409 * locks for reading have been unlocked, the waiting thread is woken up
2410 * and can lock @lock for writing.
2411 **/
2412 void
g_static_rw_lock_reader_unlock(GStaticRWLock * lock)2413 g_static_rw_lock_reader_unlock (GStaticRWLock* lock)
2414 {
2415 g_return_if_fail (lock);
2416
2417 if (!g_threads_got_initialized)
2418 return;
2419
2420 g_static_mutex_lock (&lock->mutex);
2421 lock->read_counter--;
2422 if (lock->read_counter == 0)
2423 g_static_rw_lock_signal (lock);
2424 g_static_mutex_unlock (&lock->mutex);
2425 }
2426
2427 /**
2428 * g_static_rw_lock_writer_lock:
2429 * @lock: a #GStaticRWLock to lock for writing.
2430 *
2431 * Locks @lock for writing. If @lock is already locked for writing or
2432 * reading by other threads, this function will block until @lock is
2433 * completely unlocked and then lock @lock for writing. While this
2434 * functions waits to lock @lock, no other thread can lock @lock for
2435 * reading. When @lock is locked for writing, no other thread can lock
2436 * @lock (neither for reading nor writing). This lock has to be
2437 * unlocked by g_static_rw_lock_writer_unlock().
2438 **/
2439 void
g_static_rw_lock_writer_lock(GStaticRWLock * lock)2440 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
2441 {
2442 g_return_if_fail (lock);
2443
2444 if (!g_threads_got_initialized)
2445 return;
2446
2447 g_static_mutex_lock (&lock->mutex);
2448 lock->want_to_write++;
2449 while (lock->have_writer || lock->read_counter)
2450 g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
2451 lock->want_to_write--;
2452 lock->have_writer = TRUE;
2453 g_static_mutex_unlock (&lock->mutex);
2454 }
2455
2456 /**
2457 * g_static_rw_lock_writer_trylock:
2458 * @lock: a #GStaticRWLock to lock for writing.
2459 * @Returns: %TRUE, if @lock could be locked for writing.
2460 *
2461 * Tries to lock @lock for writing. If @lock is already locked (for
2462 * either reading or writing) by another thread, it immediately returns
2463 * %FALSE. Otherwise it locks @lock for writing and returns %TRUE. This
2464 * lock has to be unlocked by g_static_rw_lock_writer_unlock().
2465 **/
2466 gboolean
g_static_rw_lock_writer_trylock(GStaticRWLock * lock)2467 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
2468 {
2469 gboolean ret_val = FALSE;
2470
2471 g_return_val_if_fail (lock, FALSE);
2472
2473 if (!g_threads_got_initialized)
2474 return TRUE;
2475
2476 g_static_mutex_lock (&lock->mutex);
2477 if (!lock->have_writer && !lock->read_counter)
2478 {
2479 lock->have_writer = TRUE;
2480 ret_val = TRUE;
2481 }
2482 g_static_mutex_unlock (&lock->mutex);
2483 return ret_val;
2484 }
2485
2486 /**
2487 * g_static_rw_lock_writer_unlock:
2488 * @lock: a #GStaticRWLock to unlock after writing.
2489 *
2490 * Unlocks @lock. If a thread is waiting to lock @lock for writing and
2491 * all locks for reading have been unlocked, the waiting thread is
2492 * woken up and can lock @lock for writing. If no thread is waiting to
2493 * lock @lock for writing, and some thread or threads are waiting to
2494 * lock @lock for reading, the waiting threads are woken up and can
2495 * lock @lock for reading.
2496 **/
2497 void
g_static_rw_lock_writer_unlock(GStaticRWLock * lock)2498 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
2499 {
2500 g_return_if_fail (lock);
2501
2502 if (!g_threads_got_initialized)
2503 return;
2504
2505 g_static_mutex_lock (&lock->mutex);
2506 lock->have_writer = FALSE;
2507 g_static_rw_lock_signal (lock);
2508 g_static_mutex_unlock (&lock->mutex);
2509 }
2510
2511 /**
2512 * g_static_rw_lock_free:
2513 * @lock: a #GStaticRWLock to be freed.
2514 *
2515 * Releases all resources allocated to @lock.
2516 *
2517 * You don't have to call this functions for a #GStaticRWLock with an
2518 * unbounded lifetime, i.e. objects declared 'static', but if you have
2519 * a #GStaticRWLock as a member of a structure, and the structure is
2520 * freed, you should also free the #GStaticRWLock.
2521 **/
2522 void
g_static_rw_lock_free(GStaticRWLock * lock)2523 g_static_rw_lock_free (GStaticRWLock* lock)
2524 {
2525 g_return_if_fail (lock);
2526
2527 if (lock->read_cond)
2528 {
2529 g_cond_free (lock->read_cond);
2530 lock->read_cond = NULL;
2531 }
2532 if (lock->write_cond)
2533 {
2534 g_cond_free (lock->write_cond);
2535 lock->write_cond = NULL;
2536 }
2537 g_static_mutex_free (&lock->mutex);
2538 }
2539
2540 /* Unsorted {{{1 ---------------------------------------------------------- */
2541
2542 /**
2543 * g_thread_foreach
2544 * @thread_func: function to call for all GThread structures
2545 * @user_data: second argument to @thread_func
2546 *
2547 * Call @thread_func on all existing #GThread structures. Note that
2548 * threads may decide to exit while @thread_func is running, so
2549 * without intimate knowledge about the lifetime of foreign threads,
2550 * @thread_func shouldn't access the GThread* pointer passed in as
2551 * first argument. However, @thread_func will not be called for threads
2552 * which are known to have exited already.
2553 *
2554 * Due to thread lifetime checks, this function has an execution complexity
2555 * which is quadratic in the number of existing threads.
2556 *
2557 * Since: 2.10
2558 */
2559 void
g_thread_foreach(GFunc thread_func,gpointer user_data)2560 g_thread_foreach (GFunc thread_func,
2561 gpointer user_data)
2562 {
2563 GSList *slist = NULL;
2564 GRealThread *thread;
2565 g_return_if_fail (thread_func != NULL);
2566 /* snapshot the list of threads for iteration */
2567 G_LOCK (g_thread);
2568 for (thread = g_thread_all_threads; thread; thread = thread->next)
2569 slist = g_slist_prepend (slist, thread);
2570 G_UNLOCK (g_thread);
2571 /* walk the list, skipping non-existent threads */
2572 while (slist)
2573 {
2574 GSList *node = slist;
2575 slist = node->next;
2576 /* check whether the current thread still exists */
2577 G_LOCK (g_thread);
2578 for (thread = g_thread_all_threads; thread; thread = thread->next)
2579 if (thread == node->data)
2580 break;
2581 G_UNLOCK (g_thread);
2582 if (thread)
2583 thread_func (thread, user_data);
2584 g_slist_free_1 (node);
2585 }
2586 }
2587
2588 /**
2589 * g_thread_get_initialized
2590 *
2591 * Indicates if g_thread_init() has been called.
2592 *
2593 * Returns: %TRUE if threads have been initialized.
2594 *
2595 * Since: 2.20
2596 */
2597 gboolean
g_thread_get_initialized()2598 g_thread_get_initialized ()
2599 {
2600 return g_thread_supported ();
2601 }
2602