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
86 * thread has a private instance of (#GPrivate). There are facilities
87 * for one-time initialization (#GOnce, g_once_init_enter()). Finally,
88 * there are primitives to create and manage threads (#GThread).
90 * The GLib threading system used to be initialized with g_thread_init().
91 * This is no longer necessary. Since version 2.32, the GLib threading
92 * system is automatically initialized at the start of your program,
93 * and all thread-creation functions and synchronization primitives
94 * are available right away.
96 * Note that it is not safe to assume that your program has no threads
97 * even if you don't call g_thread_new() yourself. GLib and GIO can
98 * and will create threads for their own purposes in some cases, such
99 * as when using g_unix_signal_source_new() or when using #GDBus.
101 * Originally, UNIX did not have threads, and therefore some traditional
102 * UNIX APIs are problematic in threaded programs. Some notable examples
106 * C library functions that return data in statically allocated
107 * buffers, such as strtok() or strerror(). For many of these,
108 * there are thread-safe variants with a _r suffix, or you can
109 * look at corresponding GLib APIs (like g_strsplit() or g_strerror()).
112 * setenv() and unsetenv() manipulate the process environment in
113 * a not thread-safe way, and may interfere with getenv() calls
114 * in other threads. Note that getenv() calls may be
115 * <quote>hidden</quote> behind other APIs. For example, GNU gettext()
116 * calls getenv() under the covers. In general, it is best to treat
117 * the environment as readonly. If you absolutely have to modify the
118 * environment, do it early in main(), when no other threads are around yet.
121 * setlocale() changes the locale for the entire process, affecting
122 * all threads. Temporary changes to the locale are often made to
123 * change the behavior of string scanning or formatting functions
124 * like scanf() or printf(). GLib offers a number of string APIs
125 * (like g_ascii_formatd() or g_ascii_strtod()) that can often be
126 * used as an alternative. Or you can use the uselocale() function
127 * to change the locale only for the current thread.
130 * fork() only takes the calling thread into the child's copy of the
131 * process image. If other threads were executing in critical
132 * sections they could have left mutexes locked which could easily
133 * cause deadlocks in the new child. For this reason, you should
134 * call exit() or exec() as soon as possible in the child and only
135 * make signal-safe library calls before that.
138 * daemon() uses fork() in a way contrary to what is described
139 * above. It should not be used with GLib programs.
143 * GLib itself is internally completely thread-safe (all global data is
144 * automatically locked), but individual data structure instances are
145 * not automatically locked for performance reasons. For example,
146 * you must coordinate accesses to the same #GHashTable from multiple
147 * threads. The two notable exceptions from this rule are #GMainLoop
148 * and #GAsyncQueue, which <emphasis>are</emphasis> thread-safe and
149 * need no further application-level locking to be accessed from
150 * multiple threads. Most refcounting functions such as g_object_ref()
151 * are also thread-safe.
154 /* G_LOCK Documentation {{{1 ---------------------------------------------- */
158 * @name: the name of the lock
160 * The %G_LOCK_* macros provide a convenient interface to #GMutex.
161 * #G_LOCK_DEFINE defines a lock. It can appear in any place where
162 * variable definitions may appear in programs, i.e. in the first block
163 * of a function or outside of functions. The @name parameter will be
164 * mangled to get the name of the #GMutex. This means that you
165 * can use names of existing variables as the parameter - e.g. the name
166 * of the variable you intend to protect with the lock. Look at our
167 * <function>give_me_next_number()</function> example using the
171 * <title>Using the %G_LOCK_* convenience macros</title>
173 * G_LOCK_DEFINE (current_number);
176 * give_me_next_number (void)
178 * static int current_number = 0;
181 * G_LOCK (current_number);
182 * ret_val = current_number = calc_next_number (current_number);
183 * G_UNLOCK (current_number);
192 * G_LOCK_DEFINE_STATIC:
193 * @name: the name of the lock
195 * This works like #G_LOCK_DEFINE, but it creates a static object.
200 * @name: the name of the lock
202 * This declares a lock, that is defined with #G_LOCK_DEFINE in another
208 * @name: the name of the lock
210 * Works like g_mutex_lock(), but for a lock defined with
216 * @name: the name of the lock
217 * @Returns: %TRUE, if the lock could be locked.
219 * Works like g_mutex_trylock(), but for a lock defined with
225 * @name: the name of the lock
227 * Works like g_mutex_unlock(), but for a lock defined with
231 /* GMutex Documentation {{{1 ------------------------------------------ */
236 * The #GMutex struct is an opaque data structure to represent a mutex
237 * (mutual exclusion). It can be used to protect data against shared
238 * access. Take for example the following function:
241 * <title>A function which will not work in a threaded environment</title>
244 * give_me_next_number (void)
246 * static int current_number = 0;
248 * /<!-- -->* now do a very complicated calculation to calculate the new
249 * * number, this might for example be a random number generator
251 * current_number = calc_next_number (current_number);
253 * return current_number;
258 * It is easy to see that this won't work in a multi-threaded
259 * application. There current_number must be protected against shared
260 * access. A #GMutex can be used as a solution to this problem:
263 * <title>Using GMutex to protected a shared variable</title>
266 * give_me_next_number (void)
268 * static GMutex mutex;
269 * static int current_number = 0;
272 * g_mutex_lock (&mutex);
273 * ret_val = current_number = calc_next_number (current_number);
274 * g_mutex_unlock (&mutex);
281 * Notice that the #GMutex is not initialised to any particular value.
282 * Its placement in static storage ensures that it will be initialised
283 * to all-zeros, which is appropriate.
285 * If a #GMutex is placed in other contexts (eg: embedded in a struct)
286 * then it must be explicitly initialised using g_mutex_init().
288 * A #GMutex should only be accessed via <function>g_mutex_</function>
292 /* GRecMutex Documentation {{{1 -------------------------------------- */
297 * The GRecMutex struct is an opaque data structure to represent a
298 * recursive mutex. It is similar to a #GMutex with the difference
299 * that it is possible to lock a GRecMutex multiple times in the same
300 * thread without deadlock. When doing so, care has to be taken to
301 * unlock the recursive mutex as often as it has been locked.
303 * If a #GRecMutex is allocated in static storage then it can be used
304 * without initialisation. Otherwise, you should call
305 * g_rec_mutex_init() on it and g_rec_mutex_clear() when done.
307 * A GRecMutex should only be accessed with the
308 * <function>g_rec_mutex_</function> functions.
313 /* GRWLock Documentation {{{1 ---------------------------------------- */
318 * The GRWLock struct is an opaque data structure to represent a
319 * reader-writer lock. It is similar to a #GMutex in that it allows
320 * multiple threads to coordinate access to a shared resource.
322 * The difference to a mutex is that a reader-writer lock discriminates
323 * between read-only ('reader') and full ('writer') access. While only
324 * one thread at a time is allowed write access (by holding the 'writer'
325 * lock via g_rw_lock_writer_lock()), multiple threads can gain
326 * simultaneous read-only access (by holding the 'reader' lock via
327 * g_rw_lock_reader_lock()).
330 * <title>An array with access functions</title>
336 * my_array_get (guint index)
338 * gpointer retval = NULL;
343 * g_rw_lock_reader_lock (&lock);
344 * if (index < array->len)
345 * retval = g_ptr_array_index (array, index);
346 * g_rw_lock_reader_unlock (&lock);
352 * my_array_set (guint index, gpointer data)
354 * g_rw_lock_writer_lock (&lock);
357 * array = g_ptr_array_new (<!-- -->);
359 * if (index >= array->len)
360 * g_ptr_array_set_size (array, index+1);
361 * g_ptr_array_index (array, index) = data;
363 * g_rw_lock_writer_unlock (&lock);
367 * This example shows an array which can be accessed by many readers
368 * (the <function>my_array_get()</function> function) simultaneously,
369 * whereas the writers (the <function>my_array_set()</function>
370 * function) will only be allowed once at a time and only if no readers
371 * currently access the array. This is because of the potentially
372 * dangerous resizing of the array. Using these functions is fully
373 * multi-thread safe now.
377 * If a #GRWLock is allocated in static storage then it can be used
378 * without initialisation. Otherwise, you should call
379 * g_rw_lock_init() on it and g_rw_lock_clear() when done.
381 * A GRWLock should only be accessed with the
382 * <function>g_rw_lock_</function> functions.
387 /* GCond Documentation {{{1 ------------------------------------------ */
392 * The #GCond struct is an opaque data structure that represents a
393 * condition. Threads can block on a #GCond if they find a certain
394 * condition to be false. If other threads change the state of this
395 * condition they signal the #GCond, and that causes the waiting
396 * threads to be woken up.
398 * Consider the following example of a shared variable. One or more
399 * threads can wait for data to be published to the variable and when
400 * another thread publishes the data, it can signal one of the waiting
401 * threads to wake up to collect the data.
405 * Using GCond to block a thread until a condition is satisfied
408 * gpointer current_data = NULL;
413 * push_data (gpointer data)
415 * g_mutex_lock (&data_mutex);
416 * current_data = data;
417 * g_cond_signal (&data_cond);
418 * g_mutex_unlock (&data_mutex);
426 * g_mutex_lock (&data_mutex);
427 * while (!current_data)
428 * g_cond_wait (&data_cond, &data_mutex);
429 * data = current_data;
430 * current_data = NULL;
431 * g_mutex_unlock (&data_mutex);
438 * Whenever a thread calls pop_data() now, it will wait until
439 * current_data is non-%NULL, i.e. until some other thread
440 * has called push_data().
442 * The example shows that use of a condition variable must always be
443 * paired with a mutex. Without the use of a mutex, there would be a
444 * race between the check of <varname>current_data</varname> by the
445 * while loop in <function>pop_data</function> and waiting.
446 * Specifically, another thread could set <varname>pop_data</varname>
447 * after the check, and signal the cond (with nobody waiting on it)
448 * before the first thread goes to sleep. #GCond is specifically useful
449 * for its ability to release the mutex and go to sleep atomically.
451 * It is also important to use the g_cond_wait() and g_cond_wait_until()
452 * functions only inside a loop which checks for the condition to be
453 * true. See g_cond_wait() for an explanation of why the condition may
454 * not be true even after it returns.
456 * If a #GCond is allocated in static storage then it can be used
457 * without initialisation. Otherwise, you should call g_cond_init() on
458 * it and g_cond_clear() when done.
460 * A #GCond should only be accessed via the <function>g_cond_</function>
464 /* GThread Documentation {{{1 ---------------------------------------- */
469 * The #GThread struct represents a running thread. This struct
470 * is returned by g_thread_new() or g_thread_try_new(). You can
471 * obtain the #GThread struct representing the current thead by
472 * calling g_thread_self().
474 * GThread is refcounted, see g_thread_ref() and g_thread_unref().
475 * The thread represented by it holds a reference while it is running,
476 * and g_thread_join() consumes the reference that it is given, so
477 * it is normally not necessary to manage GThread references
480 * The structure is opaque -- none of its fields may be directly
486 * @data: data passed to the thread
488 * Specifies the type of the @func functions passed to g_thread_new()
489 * or g_thread_try_new().
491 * Returns: the return value of the thread
495 * g_thread_supported:
497 * This macro returns %TRUE if the thread system is initialized,
498 * and %FALSE if it is not.
500 * For language bindings, g_thread_get_initialized() provides
501 * the same functionality as a function.
503 * Returns: %TRUE, if the thread system is initialized
506 /* GThreadError {{{1 ------------------------------------------------------- */
509 * @G_THREAD_ERROR_AGAIN: a thread couldn't be created due to resource
510 * shortage. Try again later.
512 * Possible errors of thread related functions.
518 * The error domain of the GLib thread subsystem.
521 g_thread_error_quark (void)
523 return g_quark_from_static_string ("g_thread_error");
526 /* Local Data {{{1 -------------------------------------------------------- */
528 static GMutex g_once_mutex;
529 static GCond g_once_cond;
530 static GSList *g_once_init_list = NULL;
532 static void g_thread_cleanup (gpointer data);
533 static GPrivate g_thread_specific_private = G_PRIVATE_INIT (g_thread_cleanup);
535 G_LOCK_DEFINE_STATIC (g_thread_new);
537 /* GOnce {{{1 ------------------------------------------------------------- */
541 * @status: the status of the #GOnce
542 * @retval: the value returned by the call to the function, if @status
543 * is %G_ONCE_STATUS_READY
545 * A #GOnce struct controls a one-time initialization function. Any
546 * one-time initialization function must have its own unique #GOnce
555 * A #GOnce must be initialized with this macro before it can be used.
558 * GOnce my_once = G_ONCE_INIT;
566 * @G_ONCE_STATUS_NOTCALLED: the function has not been called yet.
567 * @G_ONCE_STATUS_PROGRESS: the function call is currently in progress.
568 * @G_ONCE_STATUS_READY: the function has been called.
570 * The possible statuses of a one-time initialization function
571 * controlled by a #GOnce struct.
578 * @once: a #GOnce structure
579 * @func: the #GThreadFunc function associated to @once. This function
580 * is called only once, regardless of the number of times it and
581 * its associated #GOnce struct are passed to g_once().
582 * @arg: data to be passed to @func
584 * The first call to this routine by a process with a given #GOnce
585 * struct calls @func with the given argument. Thereafter, subsequent
586 * calls to g_once() with the same #GOnce struct do not call @func
587 * again, but return the stored result of the first call. On return
588 * from g_once(), the status of @once will be %G_ONCE_STATUS_READY.
590 * For example, a mutex or a thread-specific data key must be created
591 * exactly once. In a threaded environment, calling g_once() ensures
592 * that the initialization is serialized across multiple threads.
594 * Calling g_once() recursively on the same #GOnce struct in
595 * @func will lead to a deadlock.
599 * get_debug_flags (void)
601 * static GOnce my_once = G_ONCE_INIT;
603 * g_once (&my_once, parse_debug_flags, NULL);
605 * return my_once.retval;
612 g_once_impl (GOnce *once,
616 g_mutex_lock (&g_once_mutex);
618 while (once->status == G_ONCE_STATUS_PROGRESS)
619 g_cond_wait (&g_once_cond, &g_once_mutex);
621 if (once->status != G_ONCE_STATUS_READY)
623 once->status = G_ONCE_STATUS_PROGRESS;
624 g_mutex_unlock (&g_once_mutex);
626 once->retval = func (arg);
628 g_mutex_lock (&g_once_mutex);
629 once->status = G_ONCE_STATUS_READY;
630 g_cond_broadcast (&g_once_cond);
633 g_mutex_unlock (&g_once_mutex);
640 * @value_location: location of a static initializable variable
643 * Function to be called when starting a critical initialization
644 * section. The argument @value_location must point to a static
645 * 0-initialized variable that will be set to a value other than 0 at
646 * the end of the initialization section. In combination with
647 * g_once_init_leave() and the unique address @value_location, it can
648 * be ensured that an initialization section will be executed only once
649 * during a program's life time, and that concurrent threads are
650 * blocked until initialization completed. To be used in constructs
654 * static gsize initialization_value = 0;
656 * if (g_once_init_enter (&initialization_value))
658 * gsize setup_value = 42; /** initialization code here **/
660 * g_once_init_leave (&initialization_value, setup_value);
663 * /** use initialization_value here **/
666 * Returns: %TRUE if the initialization section should be entered,
667 * %FALSE and blocks otherwise
672 (g_once_init_enter) (volatile void *pointer)
674 volatile gsize *value_location = pointer;
675 gboolean need_init = FALSE;
676 g_mutex_lock (&g_once_mutex);
677 if (g_atomic_pointer_get (value_location) == NULL)
679 if (!g_slist_find (g_once_init_list, (void*) value_location))
682 g_once_init_list = g_slist_prepend (g_once_init_list, (void*) value_location);
686 g_cond_wait (&g_once_cond, &g_once_mutex);
687 while (g_slist_find (g_once_init_list, (void*) value_location));
689 g_mutex_unlock (&g_once_mutex);
695 * @value_location: location of a static initializable variable
697 * @result: new non-0 value for *@value_location
699 * Counterpart to g_once_init_enter(). Expects a location of a static
700 * 0-initialized initialization variable, and an initialization value
701 * other than 0. Sets the variable to the initialization value, and
702 * releases concurrent threads blocking in g_once_init_enter() on this
703 * initialization variable.
708 (g_once_init_leave) (volatile void *pointer,
711 volatile gsize *value_location = pointer;
713 g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
714 g_return_if_fail (result != 0);
715 g_return_if_fail (g_once_init_list != NULL);
717 g_atomic_pointer_set (value_location, result);
718 g_mutex_lock (&g_once_mutex);
719 g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
720 g_cond_broadcast (&g_once_cond);
721 g_mutex_unlock (&g_once_mutex);
724 /* GThread {{{1 -------------------------------------------------------- */
728 * @thread: a #GThread
730 * Increase the reference count on @thread.
732 * Returns: a new reference to @thread
737 g_thread_ref (GThread *thread)
739 GRealThread *real = (GRealThread *) thread;
741 g_atomic_int_inc (&real->ref_count);
748 * @thread: a #GThread
750 * Decrease the reference count on @thread, possibly freeing all
751 * resources associated with it.
753 * Note that each thread holds a reference to its #GThread while
754 * it is running, so it is safe to drop your own reference to it
755 * if you don't need it anymore.
760 g_thread_unref (GThread *thread)
762 GRealThread *real = (GRealThread *) thread;
764 if (g_atomic_int_dec_and_test (&real->ref_count))
767 g_system_thread_free (real);
769 g_slice_free (GRealThread, real);
774 g_thread_cleanup (gpointer data)
776 g_thread_unref (data);
780 g_thread_proxy (gpointer data)
782 GRealThread* thread = data;
787 g_system_thread_set_name (thread->name);
789 /* This has to happen before G_LOCK, as that might call g_thread_self */
790 g_private_set (&g_thread_specific_private, data);
792 /* The lock makes sure that g_thread_new_internal() has a chance to
793 * setup 'func' and 'data' before we make the call.
795 G_LOCK (g_thread_new);
796 G_UNLOCK (g_thread_new);
798 thread->retval = thread->thread.func (thread->thread.data);
805 * @name: a name for the new thread
806 * @func: a function to execute in the new thread
807 * @data: an argument to supply to the new thread
809 * This function creates a new thread. The new thread starts by invoking
810 * @func with the argument data. The thread will run until @func returns
811 * or until g_thread_exit() is called from the new thread. The return value
812 * of @func becomes the return value of the thread, which can be obtained
813 * with g_thread_join().
815 * The @name can be useful for discriminating threads in a debugger.
816 * Some systems restrict the length of @name to 16 bytes.
818 * If the thread can not be created the program aborts. See
819 * g_thread_try_new() if you want to attempt to deal with failures.
821 * To free the struct returned by this function, use g_thread_unref().
822 * Note that g_thread_join() implicitly unrefs the #GThread as well.
824 * Returns: the new #GThread
829 g_thread_new (const gchar *name,
833 GError *error = NULL;
836 thread = g_thread_new_internal (name, g_thread_proxy, func, data, 0, &error);
838 if G_UNLIKELY (thread == NULL)
839 g_error ("creating thread '%s': %s", name ? name : "", error->message);
846 * @name: a name for the new thread
847 * @func: a function to execute in the new thread
848 * @data: an argument to supply to the new thread
849 * @error: return location for error, or %NULL
851 * This function is the same as g_thread_new() except that
852 * it allows for the possibility of failure.
854 * If a thread can not be created (due to resource limits),
855 * @error is set and %NULL is returned.
857 * Returns: the new #GThread, or %NULL if an error occurred
862 g_thread_try_new (const gchar *name,
867 return g_thread_new_internal (name, g_thread_proxy, func, data, 0, error);
871 g_thread_new_internal (const gchar *name,
880 g_return_val_if_fail (func != NULL, NULL);
882 G_LOCK (g_thread_new);
883 thread = g_system_thread_new (proxy, stack_size, error);
886 thread->ref_count = 2;
888 thread->thread.joinable = TRUE;
889 thread->thread.func = func;
890 thread->thread.data = data;
893 G_UNLOCK (g_thread_new);
895 return (GThread*) thread;
900 * @retval: the return value of this thread
902 * Terminates the current thread.
904 * If another thread is waiting for us using g_thread_join() then the
905 * waiting thread will be woken up and get @retval as the return value
906 * of g_thread_join().
908 * Calling <literal>g_thread_exit (retval)</literal> is equivalent to
909 * returning @retval from the function @func, as given to g_thread_new().
912 * You must only call g_thread_exit() from a thread that you created
913 * yourself with g_thread_new() or related APIs. You must not call
914 * this function from a thread created with another threading library
915 * or or from within a #GThreadPool.
919 g_thread_exit (gpointer retval)
921 GRealThread* real = (GRealThread*) g_thread_self ();
923 if G_UNLIKELY (!real->ours)
924 g_error ("attempt to g_thread_exit() a thread not created by GLib");
926 real->retval = retval;
928 g_system_thread_exit ();
933 * @thread: a #GThread
935 * Waits until @thread finishes, i.e. the function @func, as
936 * given to g_thread_new(), returns or g_thread_exit() is called.
937 * If @thread has already terminated, then g_thread_join()
938 * returns immediately.
940 * Any thread can wait for any other thread by calling g_thread_join(),
941 * not just its 'creator'. Calling g_thread_join() from multiple threads
942 * for the same @thread leads to undefined behaviour.
944 * The value returned by @func or given to g_thread_exit() is
945 * returned by this function.
947 * g_thread_join() consumes the reference to the passed-in @thread.
948 * This will usually cause the #GThread struct and associated resources
949 * to be freed. Use g_thread_ref() to obtain an extra reference if you
950 * want to keep the GThread alive beyond the g_thread_join() call.
952 * Returns: the return value of the thread
955 g_thread_join (GThread *thread)
957 GRealThread *real = (GRealThread*) thread;
960 g_return_val_if_fail (thread, NULL);
961 g_return_val_if_fail (real->ours, NULL);
963 g_system_thread_wait (real);
965 retval = real->retval;
967 /* Just to make sure, this isn't used any more */
968 thread->joinable = 0;
970 g_thread_unref (thread);
978 * This functions returns the #GThread corresponding to the
979 * current thread. Note that this function does not increase
980 * the reference count of the returned struct.
982 * This function will return a #GThread even for threads that
983 * were not created by GLib (i.e. those created by other threading
984 * APIs). This may be useful for thread identification purposes
985 * (i.e. comparisons) but you must not use GLib functions (such
986 * as g_thread_join()) on these threads.
988 * Returns: the #GThread representing the current thread
993 GRealThread* thread = g_private_get (&g_thread_specific_private);
997 /* If no thread data is available, provide and set one.
998 * This can happen for the main thread and for threads
999 * that are not created by GLib.
1001 thread = g_slice_new0 (GRealThread);
1002 thread->ref_count = 1;
1004 g_private_set (&g_thread_specific_private, thread);
1007 return (GThread*) thread;
1011 /* vim: set foldmethod=marker: */