1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * gthread.c: MT safety related functions
5 * Copyright 1998 Sebastian Wilhelmi; University of Karlsruhe
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.
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.
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.
24 /* Prelude {{{1 ----------------------------------------------------------- */
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/.
37 /* implement gthread.h's inline functions */
38 #define G_IMPLEMENT_INLINES 1
39 #define __G_THREAD_C__
44 #include "gthreadprivate.h"
57 #endif /* G_OS_WIN32 */
60 #include "gtestutils.h"
65 * @short_description: portable support for threads, mutexes, locks,
66 * conditions and thread private data
67 * @see_also: #GThreadPool, #GAsyncQueue
69 * Threads act almost like processes, but unlike processes all threads
70 * of one process share the same memory. This is good, as it provides
71 * easy communication between the involved threads via this shared
72 * memory, and it is bad, because strange things (so called
73 * "Heisenbugs") might happen if the program is not carefully designed.
74 * In particular, due to the concurrent nature of threads, no
75 * assumptions on the order of execution of code running in different
76 * threads can be made, unless order is explicitly forced by the
77 * programmer through synchronization primitives.
79 * The aim of the thread-related functions in GLib is to provide a
80 * portable means for writing multi-threaded software. There are
81 * primitives for mutexes to protect the access to portions of memory
82 * (#GMutex, #GRecMutex and #GRWLock). There is a facility to use
83 * individual bits for locks (g_bit_lock()). There are primitives
84 * for condition variables to allow synchronization of threads (#GCond).
85 * There are primitives for thread-private data - data that every thread
86 * has a private instance of (#GPrivate, #GStaticPrivate). There are
87 * facilities for one-time initialization (#GOnce, g_once_init_enter()).
88 * Finally there are primitives to create and manage threads (#GThread).
90 * The threading system is initialized with g_thread_init().
91 * You may call any other glib functions in the main thread before
92 * g_thread_init() as long as g_thread_init() is not called from
93 * a GLib callback, or with any locks held. However, many libraries
94 * above GLib does not support late initialization of threads, so
95 * doing this should be avoided if possible.
97 * Please note that since version 2.24 the GObject initialization
98 * function g_type_init() initializes threads. Since 2.32, creating
99 * a mainloop will do so too. As a consequence, most applications,
100 * including those using GTK+ will run with threads enabled.
102 * After calling g_thread_init(), GLib is completely thread safe
103 * (all global data is automatically locked), but individual data
104 * structure instances are not automatically locked for performance
105 * reasons. So, for example you must coordinate accesses to the same
106 * #GHashTable from multiple threads. The two notable exceptions from
107 * this rule are #GMainLoop and #GAsyncQueue, which <emphasis>are</emphasis>
108 * threadsafe and need no further application-level locking to be
109 * accessed from multiple threads.
113 * G_THREADS_IMPL_POSIX:
115 * This macro is defined if POSIX style threads are used.
119 * G_THREADS_IMPL_WIN32:
121 * This macro is defined if Windows style threads are used.
124 /* G_LOCK Documentation {{{1 ---------------------------------------------- */
128 * @name: the name of the lock.
130 * The %G_LOCK_* macros provide a convenient interface to #GMutex
131 * with the advantage that they will expand to nothing in programs
132 * compiled against a thread-disabled GLib, saving code and memory
133 * there. #G_LOCK_DEFINE defines a lock. It can appear anywhere
134 * variable definitions may appear in programs, i.e. in the first block
135 * of a function or outside of functions. The @name parameter will be
136 * mangled to get the name of the #GMutex. This means that you
137 * can use names of existing variables as the parameter - e.g. the name
138 * of the variable you intent to protect with the lock. Look at our
139 * <function>give_me_next_number()</function> example using the
143 * <title>Using the %G_LOCK_* convenience macros</title>
145 * G_LOCK_DEFINE (current_number);
148 * give_me_next_number (void)
150 * static int current_number = 0;
153 * G_LOCK (current_number);
154 * ret_val = current_number = calc_next_number (current_number);
155 * G_UNLOCK (current_number);
164 * G_LOCK_DEFINE_STATIC:
165 * @name: the name of the lock.
167 * This works like #G_LOCK_DEFINE, but it creates a static object.
172 * @name: the name of the lock.
174 * This declares a lock, that is defined with #G_LOCK_DEFINE in another
180 * @name: the name of the lock.
182 * Works like g_mutex_lock(), but for a lock defined with
188 * @name: the name of the lock.
189 * @Returns: %TRUE, if the lock could be locked.
191 * Works like g_mutex_trylock(), but for a lock defined with
197 * @name: the name of the lock.
199 * Works like g_mutex_unlock(), but for a lock defined with
203 /* GMutex Documentation {{{1 ------------------------------------------ */
208 * The #GMutex struct is an opaque data structure to represent a mutex
209 * (mutual exclusion). It can be used to protect data against shared
210 * access. Take for example the following function:
213 * <title>A function which will not work in a threaded environment</title>
216 * give_me_next_number (void)
218 * static int current_number = 0;
220 * /<!-- -->* now do a very complicated calculation to calculate the new
221 * * number, this might for example be a random number generator
223 * current_number = calc_next_number (current_number);
225 * return current_number;
230 * It is easy to see that this won't work in a multi-threaded
231 * application. There current_number must be protected against shared
232 * access. A first naive implementation would be:
235 * <title>The wrong way to write a thread-safe function</title>
238 * give_me_next_number (void)
240 * static int current_number = 0;
242 * static GMutex * mutex = NULL;
244 * if (!mutex) mutex = g_mutex_new (<!-- -->);
246 * g_mutex_lock (mutex);
247 * ret_val = current_number = calc_next_number (current_number);
248 * g_mutex_unlock (mutex);
255 * This looks like it would work, but there is a race condition while
256 * constructing the mutex and this code cannot work reliable. Please do
257 * not use such constructs in your own programs! One working solution
261 * <title>A correct thread-safe function</title>
263 * static GMutex *give_me_next_number_mutex = NULL;
265 * /<!-- -->* this function must be called before any call to
266 * * give_me_next_number(<!-- -->)
268 * * it must be called exactly once.
271 * init_give_me_next_number (void)
273 * g_assert (give_me_next_number_mutex == NULL);
274 * give_me_next_number_mutex = g_mutex_new (<!-- -->);
278 * give_me_next_number (void)
280 * static int current_number = 0;
283 * g_mutex_lock (give_me_next_number_mutex);
284 * ret_val = current_number = calc_next_number (current_number);
285 * g_mutex_unlock (give_me_next_number_mutex);
292 * If a #GMutex is allocated in static storage then it can be used
293 * without initialisation. Otherwise, you should call g_mutex_init() on
294 * it and g_mutex_clear() when done.
296 * A statically initialized #GMutex provides an even simpler and safer
300 * <title>Using a statically allocated mutex</title>
303 * give_me_next_number (void)
305 * static GMutex mutex;
306 * static int current_number = 0;
309 * g_mutex_lock (&mutex);
310 * ret_val = current_number = calc_next_number (current_number);
311 * g_mutex_unlock (&mutex);
318 * A #GMutex should only be accessed via <function>g_mutex_</function>
322 /* GRecMutex Documentation {{{1 -------------------------------------- */
327 * The GRecMutex struct is an opaque data structure to represent a
328 * recursive mutex. It is similar to a #GMutex with the difference
329 * that it is possible to lock a GRecMutex multiple times in the same
330 * thread without deadlock. When doing so, care has to be taken to
331 * unlock the recursive mutex as often as it has been locked.
333 * If a #GRecMutex is allocated in static storage then it can be used
334 * without initialisation. Otherwise, you should call
335 * g_rec_mutex_init() on it and g_rec_mutex_clear() when done.
337 * A GRecMutex should only be accessed with the
338 * <function>g_rec_mutex_</function> functions.
343 /* GRWLock Documentation {{{1 ---------------------------------------- */
348 * The GRWLock struct is an opaque data structure to represent a
349 * reader-writer lock. It is similar to a #GMutex in that it allows
350 * multiple threads to coordinate access to a shared resource.
352 * The difference to a mutex is that a reader-writer lock discriminates
353 * between read-only ('reader') and full ('writer') access. While only
354 * one thread at a time is allowed write access (by holding the 'writer'
355 * lock via g_rw_lock_writer_lock()), multiple threads can gain
356 * simultaneous read-only access (by holding the 'reader' lock via
357 * g_rw_lock_reader_lock()).
360 * <title>An array with access functions</title>
366 * my_array_get (guint index)
368 * gpointer retval = NULL;
373 * g_rw_lock_reader_lock (&lock);
374 * if (index < array->len)
375 * retval = g_ptr_array_index (array, index);
376 * g_rw_lock_reader_unlock (&lock);
382 * my_array_set (guint index, gpointer data)
384 * g_rw_lock_writer_lock (&lock);
387 * array = g_ptr_array_new (<!-- -->);
389 * if (index >= array->len)
390 * g_ptr_array_set_size (array, index+1);
391 * g_ptr_array_index (array, index) = data;
393 * g_rw_lock_writer_unlock (&lock);
397 * This example shows an array which can be accessed by many readers
398 * (the <function>my_array_get()</function> function) simultaneously,
399 * whereas the writers (the <function>my_array_set()</function>
400 * function) will only be allowed once at a time and only if no readers
401 * currently access the array. This is because of the potentially
402 * dangerous resizing of the array. Using these functions is fully
403 * multi-thread safe now.
407 * If a #GRWLock is allocated in static storage then it can be used
408 * without initialisation. Otherwise, you should call
409 * g_rw_lock_init() on it and g_rw_lock_clear() when done.
411 * A GRWLock should only be accessed with the
412 * <function>g_rw_lock_</function> functions.
417 /* GCond Documentation {{{1 ------------------------------------------ */
422 * The #GCond struct is an opaque data structure that represents a
423 * condition. Threads can block on a #GCond if they find a certain
424 * condition to be false. If other threads change the state of this
425 * condition they signal the #GCond, and that causes the waiting
426 * threads to be woken up.
430 * Using GCond to block a thread until a condition is satisfied
433 * GCond* data_cond = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
434 * GMutex* data_mutex = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
435 * gpointer current_data = NULL;
438 * push_data (gpointer data)
440 * g_mutex_lock (data_mutex);
441 * current_data = data;
442 * g_cond_signal (data_cond);
443 * g_mutex_unlock (data_mutex);
451 * g_mutex_lock (data_mutex);
452 * while (!current_data)
453 * g_cond_wait (data_cond, data_mutex);
454 * data = current_data;
455 * current_data = NULL;
456 * g_mutex_unlock (data_mutex);
463 * Whenever a thread calls pop_data() now, it will wait until
464 * current_data is non-%NULL, i.e. until some other thread
465 * has called push_data().
467 * <note><para>It is important to use the g_cond_wait() and
468 * g_cond_timed_wait() functions only inside a loop which checks for the
469 * condition to be true. It is not guaranteed that the waiting thread
470 * will find the condition fulfilled after it wakes up, even if the
471 * signaling thread left the condition in that state: another thread may
472 * have altered the condition before the waiting thread got the chance
473 * to be woken up, even if the condition itself is protected by a
474 * #GMutex, like above.</para></note>
476 * If a #GCond is allocated in static storage then it can be used
477 * without initialisation. Otherwise, you should call g_cond_init() on
478 * it and g_cond_clear() when done.
480 * A #GCond should only be accessed via the <function>g_cond_</function>
484 /* GThread Documentation {{{1 ---------------------------------------- */
489 * The #GThread struct represents a running thread.
491 * Resources for a joinable thread are not fully released
492 * until g_thread_join() is called for that thread.
497 * @data: data passed to the thread
498 * @Returns: the return value of the thread, which will be returned by
501 * Specifies the type of the @func functions passed to
502 * g_thread_create() or g_thread_create_full().
506 * g_thread_supported:
508 * This macro returns %TRUE if the thread system is initialized,
509 * and %FALSE if it is not.
511 * For language bindings, g_thread_get_initialized() provides
512 * the same functionality as a function.
514 * Returns: %TRUE, if the thread system is initialized
517 /* GThreadError {{{1 ------------------------------------------------------- */
520 * @G_THREAD_ERROR_AGAIN: a thread couldn't be created due to resource
521 * shortage. Try again later.
523 * Possible errors of thread related functions.
529 * The error domain of the GLib thread subsystem.
532 g_thread_error_quark (void)
534 return g_quark_from_static_string ("g_thread_error");
537 /* Local Data {{{1 -------------------------------------------------------- */
539 gboolean g_threads_got_initialized = FALSE;
540 GSystemThread zero_thread; /* This is initialized to all zero */
543 static GCond g_once_cond;
544 static GSList *g_once_init_list = NULL;
546 static void g_thread_cleanup (gpointer data);
547 static GPrivate g_thread_specific_private = G_PRIVATE_INIT (g_thread_cleanup);
549 G_LOCK_DEFINE_STATIC (g_thread_new);
551 /* Initialisation {{{1 ---------------------------------------------------- */
555 * @vtable: a function table of type #GThreadFunctions, that provides
556 * the entry points to the thread system to be used. Since 2.32,
557 * this parameter is ignored and should always be %NULL
559 * If you use GLib from more than one thread, you must initialize the
560 * thread system by calling g_thread_init().
562 * Since version 2.24, calling g_thread_init() multiple times is allowed,
563 * but nothing happens except for the first call.
565 * Since version 2.32, GLib does not support custom thread implementations
566 * anymore and the @vtable parameter is ignored and you should pass %NULL.
568 * <note><para>g_thread_init() must not be called directly or indirectly
569 * in a callback from GLib. Also no mutexes may be currently locked while
570 * calling g_thread_init().</para></note>
572 * <note><para>To use g_thread_init() in your program, you have to link
573 * with the libraries that the command <command>pkg-config --libs
574 * gthread-2.0</command> outputs. This is not the case for all the
575 * other thread-related functions of GLib. Those can be used without
576 * having to link with the thread libraries.</para></note>
580 g_thread_init_glib (void)
582 static gboolean already_done;
583 GRealThread* main_thread;
590 /* We let the main thread (the one that calls g_thread_init) inherit
591 * the static_private data set before calling g_thread_init
593 main_thread = (GRealThread*) g_thread_self ();
595 /* setup the basic threading system */
596 g_threads_got_initialized = TRUE;
597 g_private_set (&g_thread_specific_private, main_thread);
598 g_system_thread_self (&main_thread->system_thread);
600 /* accomplish log system initialization to enable messaging */
601 _g_messages_thread_init_nomessage ();
605 * g_thread_get_initialized:
607 * Indicates if g_thread_init() has been called.
609 * Returns: %TRUE if threads have been initialized.
614 g_thread_get_initialized (void)
616 return g_thread_supported ();
619 /* GOnce {{{1 ------------------------------------------------------------- */
623 * @status: the status of the #GOnce
624 * @retval: the value returned by the call to the function, if @status
625 * is %G_ONCE_STATUS_READY
627 * A #GOnce struct controls a one-time initialization function. Any
628 * one-time initialization function must have its own unique #GOnce
637 * A #GOnce must be initialized with this macro before it can be used.
640 * GOnce my_once = G_ONCE_INIT;
648 * @G_ONCE_STATUS_NOTCALLED: the function has not been called yet.
649 * @G_ONCE_STATUS_PROGRESS: the function call is currently in progress.
650 * @G_ONCE_STATUS_READY: the function has been called.
652 * The possible statuses of a one-time initialization function
653 * controlled by a #GOnce struct.
660 * @once: a #GOnce structure
661 * @func: the #GThreadFunc function associated to @once. This function
662 * is called only once, regardless of the number of times it and
663 * its associated #GOnce struct are passed to g_once().
664 * @arg: data to be passed to @func
666 * The first call to this routine by a process with a given #GOnce
667 * struct calls @func with the given argument. Thereafter, subsequent
668 * calls to g_once() with the same #GOnce struct do not call @func
669 * again, but return the stored result of the first call. On return
670 * from g_once(), the status of @once will be %G_ONCE_STATUS_READY.
672 * For example, a mutex or a thread-specific data key must be created
673 * exactly once. In a threaded environment, calling g_once() ensures
674 * that the initialization is serialized across multiple threads.
676 * Calling g_once() recursively on the same #GOnce struct in
677 * @func will lead to a deadlock.
681 * get_debug_flags (void)
683 * static GOnce my_once = G_ONCE_INIT;
685 * g_once (&my_once, parse_debug_flags, NULL);
687 * return my_once.retval;
694 g_once_impl (GOnce *once,
698 g_mutex_lock (&g_once_mutex);
700 while (once->status == G_ONCE_STATUS_PROGRESS)
701 g_cond_wait (&g_once_cond, &g_once_mutex);
703 if (once->status != G_ONCE_STATUS_READY)
705 once->status = G_ONCE_STATUS_PROGRESS;
706 g_mutex_unlock (&g_once_mutex);
708 once->retval = func (arg);
710 g_mutex_lock (&g_once_mutex);
711 once->status = G_ONCE_STATUS_READY;
712 g_cond_broadcast (&g_once_cond);
715 g_mutex_unlock (&g_once_mutex);
722 * @value_location: location of a static initializable variable
725 * Function to be called when starting a critical initialization
726 * section. The argument @value_location must point to a static
727 * 0-initialized variable that will be set to a value other than 0 at
728 * the end of the initialization section. In combination with
729 * g_once_init_leave() and the unique address @value_location, it can
730 * be ensured that an initialization section will be executed only once
731 * during a program's life time, and that concurrent threads are
732 * blocked until initialization completed. To be used in constructs
736 * static gsize initialization_value = 0;
738 * if (g_once_init_enter (&initialization_value))
740 * gsize setup_value = 42; /** initialization code here **/
742 * g_once_init_leave (&initialization_value, setup_value);
745 * /** use initialization_value here **/
748 * Returns: %TRUE if the initialization section should be entered,
749 * %FALSE and blocks otherwise
754 g_once_init_enter_impl (volatile gsize *value_location)
756 gboolean need_init = FALSE;
757 g_mutex_lock (&g_once_mutex);
758 if (g_atomic_pointer_get (value_location) == NULL)
760 if (!g_slist_find (g_once_init_list, (void*) value_location))
763 g_once_init_list = g_slist_prepend (g_once_init_list, (void*) value_location);
767 g_cond_wait (&g_once_cond, &g_once_mutex);
768 while (g_slist_find (g_once_init_list, (void*) value_location));
770 g_mutex_unlock (&g_once_mutex);
776 * @value_location: location of a static initializable variable
778 * @initialization_value: new non-0 value for *@value_location
780 * Counterpart to g_once_init_enter(). Expects a location of a static
781 * 0-initialized initialization variable, and an initialization value
782 * other than 0. Sets the variable to the initialization value, and
783 * releases concurrent threads blocking in g_once_init_enter() on this
784 * initialization variable.
789 g_once_init_leave (volatile gsize *value_location,
790 gsize initialization_value)
792 g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
793 g_return_if_fail (initialization_value != 0);
794 g_return_if_fail (g_once_init_list != NULL);
796 g_atomic_pointer_set (value_location, initialization_value);
797 g_mutex_lock (&g_once_mutex);
798 g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
799 g_cond_broadcast (&g_once_cond);
800 g_mutex_unlock (&g_once_mutex);
803 /* GThread {{{1 -------------------------------------------------------- */
806 g_thread_cleanup (gpointer data)
810 GRealThread* thread = data;
812 g_static_private_cleanup (thread);
814 /* We only free the thread structure if it isn't joinable.
815 * If it is, the structure is freed in g_thread_join()
817 if (!thread->thread.joinable)
819 if (thread->enumerable)
820 g_enumerable_thread_remove (thread);
822 /* Just to make sure, this isn't used any more */
823 g_system_thread_assign (thread->system_thread, zero_thread);
830 g_thread_create_proxy (gpointer data)
832 GRealThread* thread = data;
837 g_system_thread_set_name (thread->name);
839 /* This has to happen before G_LOCK, as that might call g_thread_self */
840 g_private_set (&g_thread_specific_private, data);
842 /* The lock makes sure that thread->system_thread is written,
843 * before thread->thread.func is called. See g_thread_create().
845 G_LOCK (g_thread_new);
846 G_UNLOCK (g_thread_new);
848 thread->retval = thread->thread.func (thread->thread.data);
855 * @name: a name for the new thread
856 * @func: a function to execute in the new thread
857 * @data: an argument to supply to the new thread
858 * @joinable: should this thread be joinable?
859 * @error: return location for error
861 * This function creates a new thread.
863 * The @name can be useful for discriminating threads in
864 * a debugger. Some systems restrict the length of @name to
867 * If @joinable is %TRUE, you can wait for this threads termination
868 * calling g_thread_join(). Otherwise the thread will just disappear
869 * when it terminates.
871 * The new thread executes the function @func with the argument @data.
872 * If the thread was created successfully, it is returned.
874 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
875 * The error is set, if and only if the function returns %NULL.
877 * Returns: the new #GThread on success
882 g_thread_new (const gchar *name,
888 return g_thread_new_internal (name, func, data, joinable, 0, FALSE, error);
893 * @name: a name for the new thread
894 * @func: a function to execute in the new thread
895 * @data: an argument to supply to the new thread
896 * @joinable: should this thread be joinable?
897 * @stack_size: a stack size for the new thread
898 * @error: return location for error
900 * This function creates a new thread.
902 * The @name can be useful for discriminating threads in
903 * a debugger. Some systems restrict the length of @name to
906 * If the underlying thread implementation supports it, the thread
907 * gets a stack size of @stack_size or the default value for the
908 * current platform, if @stack_size is 0.
910 * If @joinable is %TRUE, you can wait for this threads termination
911 * calling g_thread_join(). Otherwise the thread will just disappear
912 * when it terminates.
914 * The new thread executes the function @func with the argument @data.
915 * If the thread was created successfully, it is returned.
917 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
918 * The error is set, if and only if the function returns %NULL.
920 * <note><para>Only use a non-zero @stack_size if you
921 * really can't use the default instead. g_thread_new()
922 * does not take @stack_size, as it should only be used in cases
923 * in which it is unavoidable.</para></note>
925 * Returns: the new #GThread on success
930 g_thread_new_full (const gchar *name,
937 return g_thread_new_internal (name, func, data, joinable, stack_size, FALSE, error);
941 g_thread_new_internal (const gchar *name,
950 GError *local_error = NULL;
951 g_return_val_if_fail (func, NULL);
953 result = g_new0 (GRealThread, 1);
955 result->thread.joinable = joinable;
956 result->thread.func = func;
957 result->thread.data = data;
958 result->private_data = NULL;
959 result->enumerable = enumerable;
961 G_LOCK (g_thread_new);
962 g_system_thread_create (g_thread_create_proxy, result,
963 stack_size, joinable,
964 &result->system_thread, &local_error);
965 if (enumerable && !local_error)
966 g_enumerable_thread_add (result);
967 G_UNLOCK (g_thread_new);
971 g_propagate_error (error, local_error);
976 return (GThread*) result;
981 * @retval: the return value of this thread
983 * Exits the current thread. If another thread is waiting for that
984 * thread using g_thread_join() and the current thread is joinable, the
985 * waiting thread will be woken up and get @retval as the return value
986 * of g_thread_join(). If the current thread is not joinable, @retval
987 * is ignored. Calling
990 * g_thread_exit (retval);
993 * is equivalent to returning @retval from the function @func, as given
994 * to g_thread_create().
996 * <note><para>Never call g_thread_exit() from within a thread of a
997 * #GThreadPool, as that will mess up the bookkeeping and lead to funny
998 * and unwanted results.</para></note>
1001 g_thread_exit (gpointer retval)
1003 GRealThread* real = (GRealThread*) g_thread_self ();
1004 real->retval = retval;
1006 g_system_thread_exit ();
1011 * @thread: a #GThread to be waited for
1013 * Waits until @thread finishes, i.e. the function @func, as given to
1014 * g_thread_create(), returns or g_thread_exit() is called by @thread.
1015 * All resources of @thread including the #GThread struct are released.
1016 * @thread must have been created with @joinable=%TRUE in
1017 * g_thread_create(). The value returned by @func or given to
1018 * g_thread_exit() by @thread is returned by this function.
1020 * Returns: the return value of the thread
1023 g_thread_join (GThread *thread)
1025 GRealThread *real = (GRealThread*) thread;
1028 g_return_val_if_fail (thread, NULL);
1029 g_return_val_if_fail (thread->joinable, NULL);
1030 g_return_val_if_fail (!g_system_thread_equal (&real->system_thread, &zero_thread), NULL);
1032 g_system_thread_join (&real->system_thread);
1034 retval = real->retval;
1036 if (real->enumerable)
1037 g_enumerable_thread_remove (real);
1039 /* Just to make sure, this isn't used any more */
1040 thread->joinable = 0;
1041 g_system_thread_assign (real->system_thread, zero_thread);
1043 /* the thread structure for non-joinable threads is freed upon
1044 * thread end. We free the memory here. This will leave a loose end,
1045 * if a joinable thread is not joined.
1055 * This functions returns the #GThread corresponding to the calling
1058 * Returns: the current thread
1061 g_thread_self (void)
1063 GRealThread* thread = g_private_get (&g_thread_specific_private);
1067 /* If no thread data is available, provide and set one.
1068 * This can happen for the main thread and for threads
1069 * that are not created by GLib.
1071 thread = g_new0 (GRealThread, 1);
1072 thread->thread.joinable = FALSE; /* This is a safe guess */
1073 thread->thread.func = NULL;
1074 thread->thread.data = NULL;
1075 thread->private_data = NULL;
1076 thread->enumerable = FALSE;
1078 g_system_thread_self (&thread->system_thread);
1080 g_private_set (&g_thread_specific_private, thread);
1083 return (GThread*)thread;
1086 /* GMutex {{{1 ------------------------------------------------------ */
1091 * Allocated and initializes a new #GMutex.
1093 * Returns: a newly allocated #GMutex. Use g_mutex_free() to free
1100 mutex = g_slice_new (GMutex);
1101 g_mutex_init (mutex);
1110 * Destroys a @mutex that has been created with g_mutex_new().
1112 * Calling g_mutex_free() on a locked mutex may result
1113 * in undefined behaviour.
1116 g_mutex_free (GMutex *mutex)
1118 g_mutex_clear (mutex);
1119 g_slice_free (GMutex, mutex);
1122 /* GCond {{{1 ------------------------------------------------------ */
1127 * Allocates and initializes a new #GCond.
1129 * Returns: a newly allocated #GCond. Free with g_cond_free()
1136 cond = g_slice_new (GCond);
1146 * Destroys a #GCond that has been created with g_cond_new().
1149 g_cond_free (GCond *cond)
1151 g_cond_clear (cond);
1152 g_slice_free (GCond, cond);
1156 /* vim: set foldmethod=marker: */