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). 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 do 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 * #G_LOCK_DEFINE defines a lock. It can appear in any place where
132 * variable definitions may appear in programs, i.e. in the first block
133 * of a function or outside of functions. The @name parameter will be
134 * mangled to get the name of the #GMutex. This means that you
135 * can use names of existing variables as the parameter - e.g. the name
136 * of the variable you intend to protect with the lock. Look at our
137 * <function>give_me_next_number()</function> example using the
141 * <title>Using the %G_LOCK_* convenience macros</title>
143 * G_LOCK_DEFINE (current_number);
146 * give_me_next_number (void)
148 * static int current_number = 0;
151 * G_LOCK (current_number);
152 * ret_val = current_number = calc_next_number (current_number);
153 * G_UNLOCK (current_number);
162 * G_LOCK_DEFINE_STATIC:
163 * @name: the name of the lock
165 * This works like #G_LOCK_DEFINE, but it creates a static object.
170 * @name: the name of the lock
172 * This declares a lock, that is defined with #G_LOCK_DEFINE in another
178 * @name: the name of the lock
180 * Works like g_mutex_lock(), but for a lock defined with
186 * @name: the name of the lock
187 * @Returns: %TRUE, if the lock could be locked.
189 * Works like g_mutex_trylock(), but for a lock defined with
195 * @name: the name of the lock
197 * Works like g_mutex_unlock(), but for a lock defined with
201 /* GMutex Documentation {{{1 ------------------------------------------ */
206 * The #GMutex struct is an opaque data structure to represent a mutex
207 * (mutual exclusion). It can be used to protect data against shared
208 * access. Take for example the following function:
211 * <title>A function which will not work in a threaded environment</title>
214 * give_me_next_number (void)
216 * static int current_number = 0;
218 * /<!-- -->* now do a very complicated calculation to calculate the new
219 * * number, this might for example be a random number generator
221 * current_number = calc_next_number (current_number);
223 * return current_number;
228 * It is easy to see that this won't work in a multi-threaded
229 * application. There current_number must be protected against shared
230 * access. A first naive implementation would be:
233 * <title>The wrong way to write a thread-safe function</title>
236 * give_me_next_number (void)
238 * static int current_number = 0;
240 * static GMutex * mutex = NULL;
242 * if (!mutex) mutex = g_mutex_new (<!-- -->);
244 * g_mutex_lock (mutex);
245 * ret_val = current_number = calc_next_number (current_number);
246 * g_mutex_unlock (mutex);
253 * This looks like it would work, but there is a race condition while
254 * constructing the mutex and this code cannot work reliable. Please do
255 * not use such constructs in your own programs! One working solution
259 * <title>A correct thread-safe function</title>
261 * static GMutex *give_me_next_number_mutex = NULL;
263 * /<!-- -->* this function must be called before any call to
264 * * give_me_next_number(<!-- -->)
266 * * it must be called exactly once.
269 * init_give_me_next_number (void)
271 * g_assert (give_me_next_number_mutex == NULL);
272 * give_me_next_number_mutex = g_mutex_new (<!-- -->);
276 * give_me_next_number (void)
278 * static int current_number = 0;
281 * g_mutex_lock (give_me_next_number_mutex);
282 * ret_val = current_number = calc_next_number (current_number);
283 * g_mutex_unlock (give_me_next_number_mutex);
290 * If a #GMutex is allocated in static storage then it can be used
291 * without initialisation. Otherwise, you should call g_mutex_init() on
292 * it and g_mutex_clear() when done.
294 * A statically initialized #GMutex provides an even simpler and safer
298 * <title>Using a statically allocated mutex</title>
301 * give_me_next_number (void)
303 * static GMutex mutex;
304 * static int current_number = 0;
307 * g_mutex_lock (&mutex);
308 * ret_val = current_number = calc_next_number (current_number);
309 * g_mutex_unlock (&mutex);
316 * A #GMutex should only be accessed via <function>g_mutex_</function>
320 /* GRecMutex Documentation {{{1 -------------------------------------- */
325 * The GRecMutex struct is an opaque data structure to represent a
326 * recursive mutex. It is similar to a #GMutex with the difference
327 * that it is possible to lock a GRecMutex multiple times in the same
328 * thread without deadlock. When doing so, care has to be taken to
329 * unlock the recursive mutex as often as it has been locked.
331 * If a #GRecMutex is allocated in static storage then it can be used
332 * without initialisation. Otherwise, you should call
333 * g_rec_mutex_init() on it and g_rec_mutex_clear() when done.
335 * A GRecMutex should only be accessed with the
336 * <function>g_rec_mutex_</function> functions.
341 /* GRWLock Documentation {{{1 ---------------------------------------- */
346 * The GRWLock struct is an opaque data structure to represent a
347 * reader-writer lock. It is similar to a #GMutex in that it allows
348 * multiple threads to coordinate access to a shared resource.
350 * The difference to a mutex is that a reader-writer lock discriminates
351 * between read-only ('reader') and full ('writer') access. While only
352 * one thread at a time is allowed write access (by holding the 'writer'
353 * lock via g_rw_lock_writer_lock()), multiple threads can gain
354 * simultaneous read-only access (by holding the 'reader' lock via
355 * g_rw_lock_reader_lock()).
358 * <title>An array with access functions</title>
364 * my_array_get (guint index)
366 * gpointer retval = NULL;
371 * g_rw_lock_reader_lock (&lock);
372 * if (index < array->len)
373 * retval = g_ptr_array_index (array, index);
374 * g_rw_lock_reader_unlock (&lock);
380 * my_array_set (guint index, gpointer data)
382 * g_rw_lock_writer_lock (&lock);
385 * array = g_ptr_array_new (<!-- -->);
387 * if (index >= array->len)
388 * g_ptr_array_set_size (array, index+1);
389 * g_ptr_array_index (array, index) = data;
391 * g_rw_lock_writer_unlock (&lock);
395 * This example shows an array which can be accessed by many readers
396 * (the <function>my_array_get()</function> function) simultaneously,
397 * whereas the writers (the <function>my_array_set()</function>
398 * function) will only be allowed once at a time and only if no readers
399 * currently access the array. This is because of the potentially
400 * dangerous resizing of the array. Using these functions is fully
401 * multi-thread safe now.
405 * If a #GRWLock is allocated in static storage then it can be used
406 * without initialisation. Otherwise, you should call
407 * g_rw_lock_init() on it and g_rw_lock_clear() when done.
409 * A GRWLock should only be accessed with the
410 * <function>g_rw_lock_</function> functions.
415 /* GCond Documentation {{{1 ------------------------------------------ */
420 * The #GCond struct is an opaque data structure that represents a
421 * condition. Threads can block on a #GCond if they find a certain
422 * condition to be false. If other threads change the state of this
423 * condition they signal the #GCond, and that causes the waiting
424 * threads to be woken up.
428 * Using GCond to block a thread until a condition is satisfied
431 * GCond* data_cond = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
432 * GMutex* data_mutex = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
433 * gpointer current_data = NULL;
436 * push_data (gpointer data)
438 * g_mutex_lock (data_mutex);
439 * current_data = data;
440 * g_cond_signal (data_cond);
441 * g_mutex_unlock (data_mutex);
449 * g_mutex_lock (data_mutex);
450 * while (!current_data)
451 * g_cond_wait (data_cond, data_mutex);
452 * data = current_data;
453 * current_data = NULL;
454 * g_mutex_unlock (data_mutex);
461 * Whenever a thread calls pop_data() now, it will wait until
462 * current_data is non-%NULL, i.e. until some other thread
463 * has called push_data().
465 * <note><para>It is important to use the g_cond_wait() and
466 * g_cond_timed_wait() functions only inside a loop which checks for the
467 * condition to be true. It is not guaranteed that the waiting thread
468 * will find the condition fulfilled after it wakes up, even if the
469 * signaling thread left the condition in that state: another thread may
470 * have altered the condition before the waiting thread got the chance
471 * to be woken up, even if the condition itself is protected by a
472 * #GMutex, like above.</para></note>
474 * If a #GCond is allocated in static storage then it can be used
475 * without initialisation. Otherwise, you should call g_cond_init() on
476 * it and g_cond_clear() when done.
478 * A #GCond should only be accessed via the <function>g_cond_</function>
482 /* GThread Documentation {{{1 ---------------------------------------- */
487 * The #GThread struct represents a running thread. This struct
488 * is returned by g_thread_new() or g_thread_new_full(). You can
489 * obtain the #GThread struct representing the current thead by
490 * calling g_thread_self().
495 * @data: data passed to the thread
497 * Specifies the type of the @func functions passed to
498 * g_thread_new() or g_thread_new_full().
500 * If the thread is joinable, the return value of this function
501 * is returned by a g_thread_join() call waiting for the thread.
502 * If the thread is not joinable, the return value is ignored.
504 * Returns: the return value of the thread
508 * g_thread_supported:
510 * This macro returns %TRUE if the thread system is initialized,
511 * and %FALSE if it is not.
513 * For language bindings, g_thread_get_initialized() provides
514 * the same functionality as a function.
516 * Returns: %TRUE, if the thread system is initialized
519 /* GThreadError {{{1 ------------------------------------------------------- */
522 * @G_THREAD_ERROR_AGAIN: a thread couldn't be created due to resource
523 * shortage. Try again later.
525 * Possible errors of thread related functions.
531 * The error domain of the GLib thread subsystem.
534 g_thread_error_quark (void)
536 return g_quark_from_static_string ("g_thread_error");
539 /* Local Data {{{1 -------------------------------------------------------- */
541 gboolean g_threads_got_initialized = FALSE;
542 GSystemThread zero_thread; /* This is initialized to all zero */
545 static GCond g_once_cond;
546 static GSList *g_once_init_list = NULL;
548 static void g_thread_cleanup (gpointer data);
549 static GPrivate g_thread_specific_private = G_PRIVATE_INIT (g_thread_cleanup);
551 G_LOCK_DEFINE_STATIC (g_thread_new);
553 /* Initialisation {{{1 ---------------------------------------------------- */
557 * @vtable: a function table of type #GThreadFunctions, that provides
558 * the entry points to the thread system to be used. Since 2.32,
559 * this parameter is ignored and should always be %NULL
561 * If you use GLib from more than one thread, you must initialize the
562 * thread system by calling g_thread_init().
564 * Since version 2.24, calling g_thread_init() multiple times is allowed,
565 * but nothing happens except for the first call.
567 * Since version 2.32, GLib does not support custom thread implementations
568 * anymore and the @vtable parameter is ignored and you should pass %NULL.
570 * <note><para>g_thread_init() must not be called directly or indirectly
571 * in a callback from GLib. Also no mutexes may be currently locked while
572 * calling g_thread_init().</para></note>
574 * <note><para>To use g_thread_init() in your program, you have to link
575 * with the libraries that the command <command>pkg-config --libs
576 * gthread-2.0</command> outputs. This is not the case for all the
577 * other thread-related functions of GLib. Those can be used without
578 * having to link with the thread libraries.</para></note>
582 g_thread_init_glib (void)
584 static gboolean already_done;
585 GRealThread *main_thread;
592 /* We let the main thread (the one that calls g_thread_init) inherit
593 * the static_private data set before calling g_thread_init
595 main_thread = (GRealThread*) g_thread_self ();
597 /* setup the basic threading system */
598 g_threads_got_initialized = TRUE;
599 g_private_set (&g_thread_specific_private, main_thread);
600 g_system_thread_self (&main_thread->system_thread);
602 /* accomplish log system initialization to enable messaging */
603 _g_messages_thread_init_nomessage ();
607 * g_thread_get_initialized:
609 * Indicates if g_thread_init() has been called.
611 * Returns: %TRUE if threads have been initialized.
616 g_thread_get_initialized (void)
618 return g_thread_supported ();
621 /* GOnce {{{1 ------------------------------------------------------------- */
625 * @status: the status of the #GOnce
626 * @retval: the value returned by the call to the function, if @status
627 * is %G_ONCE_STATUS_READY
629 * A #GOnce struct controls a one-time initialization function. Any
630 * one-time initialization function must have its own unique #GOnce
639 * A #GOnce must be initialized with this macro before it can be used.
642 * GOnce my_once = G_ONCE_INIT;
650 * @G_ONCE_STATUS_NOTCALLED: the function has not been called yet.
651 * @G_ONCE_STATUS_PROGRESS: the function call is currently in progress.
652 * @G_ONCE_STATUS_READY: the function has been called.
654 * The possible statuses of a one-time initialization function
655 * controlled by a #GOnce struct.
662 * @once: a #GOnce structure
663 * @func: the #GThreadFunc function associated to @once. This function
664 * is called only once, regardless of the number of times it and
665 * its associated #GOnce struct are passed to g_once().
666 * @arg: data to be passed to @func
668 * The first call to this routine by a process with a given #GOnce
669 * struct calls @func with the given argument. Thereafter, subsequent
670 * calls to g_once() with the same #GOnce struct do not call @func
671 * again, but return the stored result of the first call. On return
672 * from g_once(), the status of @once will be %G_ONCE_STATUS_READY.
674 * For example, a mutex or a thread-specific data key must be created
675 * exactly once. In a threaded environment, calling g_once() ensures
676 * that the initialization is serialized across multiple threads.
678 * Calling g_once() recursively on the same #GOnce struct in
679 * @func will lead to a deadlock.
683 * get_debug_flags (void)
685 * static GOnce my_once = G_ONCE_INIT;
687 * g_once (&my_once, parse_debug_flags, NULL);
689 * return my_once.retval;
696 g_once_impl (GOnce *once,
700 g_mutex_lock (&g_once_mutex);
702 while (once->status == G_ONCE_STATUS_PROGRESS)
703 g_cond_wait (&g_once_cond, &g_once_mutex);
705 if (once->status != G_ONCE_STATUS_READY)
707 once->status = G_ONCE_STATUS_PROGRESS;
708 g_mutex_unlock (&g_once_mutex);
710 once->retval = func (arg);
712 g_mutex_lock (&g_once_mutex);
713 once->status = G_ONCE_STATUS_READY;
714 g_cond_broadcast (&g_once_cond);
717 g_mutex_unlock (&g_once_mutex);
724 * @value_location: location of a static initializable variable
727 * Function to be called when starting a critical initialization
728 * section. The argument @value_location must point to a static
729 * 0-initialized variable that will be set to a value other than 0 at
730 * the end of the initialization section. In combination with
731 * g_once_init_leave() and the unique address @value_location, it can
732 * be ensured that an initialization section will be executed only once
733 * during a program's life time, and that concurrent threads are
734 * blocked until initialization completed. To be used in constructs
738 * static gsize initialization_value = 0;
740 * if (g_once_init_enter (&initialization_value))
742 * gsize setup_value = 42; /** initialization code here **/
744 * g_once_init_leave (&initialization_value, setup_value);
747 * /** use initialization_value here **/
750 * Returns: %TRUE if the initialization section should be entered,
751 * %FALSE and blocks otherwise
756 g_once_init_enter_impl (volatile gsize *value_location)
758 gboolean need_init = FALSE;
759 g_mutex_lock (&g_once_mutex);
760 if (g_atomic_pointer_get (value_location) == NULL)
762 if (!g_slist_find (g_once_init_list, (void*) value_location))
765 g_once_init_list = g_slist_prepend (g_once_init_list, (void*) value_location);
769 g_cond_wait (&g_once_cond, &g_once_mutex);
770 while (g_slist_find (g_once_init_list, (void*) value_location));
772 g_mutex_unlock (&g_once_mutex);
778 * @value_location: location of a static initializable variable
780 * @initialization_value: new non-0 value for *@value_location
782 * Counterpart to g_once_init_enter(). Expects a location of a static
783 * 0-initialized initialization variable, and an initialization value
784 * other than 0. Sets the variable to the initialization value, and
785 * releases concurrent threads blocking in g_once_init_enter() on this
786 * initialization variable.
791 g_once_init_leave (volatile gsize *value_location,
792 gsize initialization_value)
794 g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
795 g_return_if_fail (initialization_value != 0);
796 g_return_if_fail (g_once_init_list != NULL);
798 g_atomic_pointer_set (value_location, initialization_value);
799 g_mutex_lock (&g_once_mutex);
800 g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
801 g_cond_broadcast (&g_once_cond);
802 g_mutex_unlock (&g_once_mutex);
805 /* GThread {{{1 -------------------------------------------------------- */
808 g_thread_cleanup (gpointer data)
812 GRealThread* thread = data;
814 g_static_private_cleanup (thread);
816 /* We only free the thread structure if it isn't joinable.
817 * If it is, the structure is freed in g_thread_join()
819 if (!thread->thread.joinable)
821 if (thread->enumerable)
822 g_enumerable_thread_remove (thread);
824 /* Just to make sure, this isn't used any more */
825 g_system_thread_assign (thread->system_thread, zero_thread);
832 g_thread_create_proxy (gpointer data)
834 GRealThread* thread = data;
839 g_system_thread_set_name (thread->name);
841 /* This has to happen before G_LOCK, as that might call g_thread_self */
842 g_private_set (&g_thread_specific_private, data);
844 /* The lock makes sure that thread->system_thread is written,
845 * before thread->thread.func is called. See g_thread_new_internal().
847 G_LOCK (g_thread_new);
848 G_UNLOCK (g_thread_new);
850 thread->retval = thread->thread.func (thread->thread.data);
857 * @name: a name for the new thread
858 * @func: a function to execute in the new thread
859 * @data: an argument to supply to the new thread
860 * @joinable: should this thread be joinable?
861 * @error: return location for error
863 * This function creates a new thread. The new thread starts by
864 * invoking @func with the argument data. The thread will run
865 * until @func returns or until g_thread_exit() is called.
867 * The @name can be useful for discriminating threads in
868 * a debugger. Some systems restrict the length of @name to
871 * If @joinable is %TRUE, you can wait for this threads termination
872 * calling g_thread_join(). Resources for a joinable thread are not
873 * fully released until g_thread_join() is called for that thread.
874 * Otherwise the thread will just disappear when it terminates.
876 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
877 * The error is set, if and only if the function returns %NULL.
879 * Returns: the new #GThread, or %NULL if an error occurred
884 g_thread_new (const gchar *name,
890 return g_thread_new_internal (name, func, data, joinable, 0, FALSE, error);
895 * @name: a name for the new thread
896 * @func: a function to execute in the new thread
897 * @data: an argument to supply to the new thread
898 * @joinable: should this thread be joinable?
899 * @stack_size: a stack size for the new thread
900 * @error: return location for error
902 * This function creates a new thread. The new thread starts by
903 * invoking @func with the argument data. The thread will run
904 * until @func returns or until g_thread_exit() is called.
906 * The @name can be useful for discriminating threads in
907 * a debugger. Some systems restrict the length of @name to
910 * If the underlying thread implementation supports it, the thread
911 * gets a stack size of @stack_size or the default value for the
912 * current platform, if @stack_size is 0. Note that you should only
913 * use a non-zero @stack_size if you really can't use the default.
914 * In most cases, using g_thread_new() (which doesn't take a
915 * @stack_size) is better.
917 * If @joinable is %TRUE, you can wait for this threads termination
918 * calling g_thread_join(). Resources for a joinable thread are not
919 * fully released until g_thread_join() is called for that thread.
920 * Otherwise the thread will just disappear when it terminates.
922 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
923 * The error is set, if and only if the function returns %NULL.
925 * Returns: the new #GThread, or %NULL if an error occurred
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;
952 g_return_val_if_fail (func != NULL, NULL);
954 result = g_new0 (GRealThread, 1);
956 result->thread.joinable = joinable;
957 result->thread.func = func;
958 result->thread.data = data;
959 result->private_data = NULL;
960 result->enumerable = enumerable;
962 G_LOCK (g_thread_new);
963 g_system_thread_create (g_thread_create_proxy, result,
964 stack_size, joinable,
965 &result->system_thread, &local_error);
966 if (enumerable && !local_error)
967 g_enumerable_thread_add (result);
968 G_UNLOCK (g_thread_new);
972 g_propagate_error (error, local_error);
977 return (GThread*) result;
982 * @retval: the return value of this thread
984 * Terminates the current thread.
986 * If another thread is waiting for that thread using g_thread_join()
987 * and the current thread is joinable, the waiting thread will be woken
988 * up and get @retval as the return value of g_thread_join(). If the
989 * current thread is not joinable, @retval is ignored.
991 * Calling <literal>g_thread_exit (retval)</literal> is equivalent to
992 * returning @retval from the function @func, as given to g_thread_new().
994 * <note><para>Never call g_thread_exit() from within a thread of a
995 * #GThreadPool, as that will mess up the bookkeeping and lead to funny
996 * and unwanted results.</para></note>
999 g_thread_exit (gpointer retval)
1001 GRealThread* real = (GRealThread*) g_thread_self ();
1002 real->retval = retval;
1004 g_system_thread_exit ();
1009 * @thread: a joinable #GThread
1011 * Waits until @thread finishes, i.e. the function @func, as
1012 * given to g_thread_new(), returns or g_thread_exit() is called.
1013 * If @thread has already terminated, then g_thread_join()
1014 * returns immediately. @thread must be joinable.
1016 * Any thread can wait for any other (joinable) thread by calling
1017 * g_thread_join(), not just its 'creator'. Calling g_thread_join()
1018 * from multiple threads for the same @thread leads to undefined
1021 * The value returned by @func or given to g_thread_exit() is
1022 * returned by this function.
1024 * All resources of @thread including the #GThread struct are
1025 * released before g_thread_join() returns.
1027 * Returns: the return value of the thread
1030 g_thread_join (GThread *thread)
1032 GRealThread *real = (GRealThread*) thread;
1035 g_return_val_if_fail (thread, NULL);
1036 g_return_val_if_fail (thread->joinable, NULL);
1037 g_return_val_if_fail (!g_system_thread_equal (&real->system_thread, &zero_thread), NULL);
1039 g_system_thread_join (&real->system_thread);
1041 retval = real->retval;
1043 if (real->enumerable)
1044 g_enumerable_thread_remove (real);
1046 /* Just to make sure, this isn't used any more */
1047 thread->joinable = 0;
1048 g_system_thread_assign (real->system_thread, zero_thread);
1050 /* the thread structure for non-joinable threads is freed upon
1051 * thread end. We free the memory here. This will leave a loose end,
1052 * if a joinable thread is not joined.
1062 * This functions returns the #GThread corresponding to the
1065 * Returns: the #GThread representing the current thread
1068 g_thread_self (void)
1070 GRealThread* thread = g_private_get (&g_thread_specific_private);
1074 /* If no thread data is available, provide and set one.
1075 * This can happen for the main thread and for threads
1076 * that are not created by GLib.
1078 thread = g_new0 (GRealThread, 1);
1079 thread->thread.joinable = FALSE; /* This is a safe guess */
1080 thread->thread.func = NULL;
1081 thread->thread.data = NULL;
1082 thread->private_data = NULL;
1083 thread->enumerable = FALSE;
1085 g_system_thread_self (&thread->system_thread);
1087 g_private_set (&g_thread_specific_private, thread);
1090 return (GThread*)thread;
1093 /* GMutex {{{1 ------------------------------------------------------ */
1098 * Allocates and initializes a new #GMutex.
1100 * Returns: a newly allocated #GMutex. Use g_mutex_free() to free
1107 mutex = g_slice_new (GMutex);
1108 g_mutex_init (mutex);
1117 * Destroys a @mutex that has been created with g_mutex_new().
1119 * Calling g_mutex_free() on a locked mutex may result
1120 * in undefined behaviour.
1123 g_mutex_free (GMutex *mutex)
1125 g_mutex_clear (mutex);
1126 g_slice_free (GMutex, mutex);
1129 /* GCond {{{1 ------------------------------------------------------ */
1134 * Allocates and initializes a new #GCond.
1136 * Returns: a newly allocated #GCond. Free with g_cond_free()
1143 cond = g_slice_new (GCond);
1153 * Destroys a #GCond that has been created with g_cond_new().
1155 * Calling g_cond_free() for a #GCond on which threads are
1156 * blocking leads to undefined behaviour.
1159 g_cond_free (GCond *cond)
1161 g_cond_clear (cond);
1162 g_slice_free (GCond, cond);
1166 /* vim: set foldmethod=marker: */