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"
45 #include "deprecated/gthread.h"
58 #endif /* G_OS_WIN32 */
63 #include "gtestutils.h"
68 * @short_description: portable support for threads, mutexes, locks,
69 * conditions and thread private data
70 * @see_also: #GThreadPool, #GAsyncQueue
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.
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, #GRecMutex and #GRWLock). There is a facility to use
86 * individual bits for locks (g_bit_lock()). There are primitives
87 * for condition variables to allow synchronization of threads (#GCond).
88 * There are primitives for thread-private data - data that every thread
89 * has a private instance of (#GPrivate, #GStaticPrivate). There are
90 * facilities for one-time initialization (#GOnce, g_once_init_enter()).
91 * Finally there are primitives to create and manage threads (#GThread).
93 * The threading system is initialized with g_thread_init().
94 * You may call any other glib functions in the main thread before
95 * g_thread_init() as long as g_thread_init() is not called from
96 * a GLib callback, or with any locks held. However, many libraries
97 * above GLib does not support late initialization of threads, so
98 * doing this should be avoided if possible.
100 * Please note that since version 2.24 the GObject initialization
101 * function g_type_init() initializes threads. Since 2.32, creating
102 * a mainloop will do so too. As a consequence, most applications,
103 * including those using GTK+ will run with threads enabled.
105 * After calling g_thread_init(), GLib is completely thread safe
106 * (all global data is automatically locked), but individual data
107 * structure instances are not automatically locked for performance
108 * reasons. So, for example you must coordinate accesses to the same
109 * #GHashTable from multiple threads. The two notable exceptions from
110 * this rule are #GMainLoop and #GAsyncQueue, which <emphasis>are</emphasis>
111 * threadsafe and need no further application-level locking to be
112 * accessed from multiple threads.
116 * G_THREADS_IMPL_POSIX:
118 * This macro is defined if POSIX style threads are used.
122 * G_THREADS_IMPL_WIN32:
124 * This macro is defined if Windows style threads are used.
127 /* G_LOCK Documentation {{{1 ---------------------------------------------- */
131 * @name: the name of the lock.
133 * The %G_LOCK_* macros provide a convenient interface to #GMutex
134 * with the advantage that they will expand to nothing in programs
135 * compiled against a thread-disabled GLib, saving code and memory
136 * there. #G_LOCK_DEFINE defines a lock. It can appear anywhere
137 * variable definitions may appear in programs, i.e. in the first block
138 * of a function or outside of functions. The @name parameter will be
139 * mangled to get the name of the #GMutex. This means that you
140 * can use names of existing variables as the parameter - e.g. the name
141 * of the variable you intent to protect with the lock. Look at our
142 * <function>give_me_next_number()</function> example using the
146 * <title>Using the %G_LOCK_* convenience macros</title>
148 * G_LOCK_DEFINE (current_number);
151 * give_me_next_number (void)
153 * static int current_number = 0;
156 * G_LOCK (current_number);
157 * ret_val = current_number = calc_next_number (current_number);
158 * G_UNLOCK (current_number);
167 * G_LOCK_DEFINE_STATIC:
168 * @name: the name of the lock.
170 * This works like #G_LOCK_DEFINE, but it creates a static object.
175 * @name: the name of the lock.
177 * This declares a lock, that is defined with #G_LOCK_DEFINE in another
183 * @name: the name of the lock.
185 * Works like g_mutex_lock(), but for a lock defined with
191 * @name: the name of the lock.
192 * @Returns: %TRUE, if the lock could be locked.
194 * Works like g_mutex_trylock(), but for a lock defined with
200 * @name: the name of the lock.
202 * Works like g_mutex_unlock(), but for a lock defined with
206 /* GMutex Documentation {{{1 ------------------------------------------ */
211 * The #GMutex struct is an opaque data structure to represent a mutex
212 * (mutual exclusion). It can be used to protect data against shared
213 * access. Take for example the following function:
216 * <title>A function which will not work in a threaded environment</title>
219 * give_me_next_number (void)
221 * static int current_number = 0;
223 * /<!-- -->* now do a very complicated calculation to calculate the new
224 * * number, this might for example be a random number generator
226 * current_number = calc_next_number (current_number);
228 * return current_number;
233 * It is easy to see that this won't work in a multi-threaded
234 * application. There current_number must be protected against shared
235 * access. A first naive implementation would be:
238 * <title>The wrong way to write a thread-safe function</title>
241 * give_me_next_number (void)
243 * static int current_number = 0;
245 * static GMutex * mutex = NULL;
247 * if (!mutex) mutex = g_mutex_new (<!-- -->);
249 * g_mutex_lock (mutex);
250 * ret_val = current_number = calc_next_number (current_number);
251 * g_mutex_unlock (mutex);
258 * This looks like it would work, but there is a race condition while
259 * constructing the mutex and this code cannot work reliable. Please do
260 * not use such constructs in your own programs! One working solution
264 * <title>A correct thread-safe function</title>
266 * static GMutex *give_me_next_number_mutex = NULL;
268 * /<!-- -->* this function must be called before any call to
269 * * give_me_next_number(<!-- -->)
271 * * it must be called exactly once.
274 * init_give_me_next_number (void)
276 * g_assert (give_me_next_number_mutex == NULL);
277 * give_me_next_number_mutex = g_mutex_new (<!-- -->);
281 * give_me_next_number (void)
283 * static int current_number = 0;
286 * g_mutex_lock (give_me_next_number_mutex);
287 * ret_val = current_number = calc_next_number (current_number);
288 * g_mutex_unlock (give_me_next_number_mutex);
295 * A statically initialized #GMutex provides an even simpler and safer
299 * <title>Using a statically allocated mutex</title>
302 * give_me_next_number (void)
304 * static GMutex mutex = G_MUTEX_INIT;
305 * static int current_number = 0;
308 * g_mutex_lock (&mutex);
309 * ret_val = current_number = calc_next_number (current_number);
310 * g_mutex_unlock (&mutex);
317 * A #GMutex should only be accessed via <function>g_mutex_</function>
324 * Initializer for statically allocated #GMutexes.
325 * Alternatively, g_mutex_init() can be used.
328 * GMutex mutex = G_MUTEX_INIT;
334 /* GRecMutex Documentation {{{1 -------------------------------------- */
339 * The GRecMutex struct is an opaque data structure to represent a
340 * recursive mutex. It is similar to a #GMutex with the difference
341 * that it is possible to lock a GRecMutex multiple times in the same
342 * thread without deadlock. When doing so, care has to be taken to
343 * unlock the recursive mutex as often as it has been locked.
345 * A GRecMutex should only be accessed with the
346 * <function>g_rec_mutex_</function> functions. Before a GRecMutex
347 * can be used, it has to be initialized with #G_REC_MUTEX_INIT or
348 * g_rec_mutex_init().
356 * Initializer for statically allocated #GRecMutexes.
357 * Alternatively, g_rec_mutex_init() can be used.
360 * GRecMutex mutex = G_REC_MUTEX_INIT;
366 /* GRWLock Documentation {{{1 ---------------------------------------- */
371 * The GRWLock struct is an opaque data structure to represent a
372 * reader-writer lock. It is similar to a #GMutex in that it allows
373 * multiple threads to coordinate access to a shared resource.
375 * The difference to a mutex is that a reader-writer lock discriminates
376 * between read-only ('reader') and full ('writer') access. While only
377 * one thread at a time is allowed write access (by holding the 'writer'
378 * lock via g_rw_lock_writer_lock()), multiple threads can gain
379 * simultaneous read-only access (by holding the 'reader' lock via
380 * g_rw_lock_reader_lock()).
383 * <title>An array with access functions</title>
385 * GRWLock lock = G_RW_LOCK_INIT;
389 * my_array_get (guint index)
391 * gpointer retval = NULL;
396 * g_rw_lock_reader_lock (&lock);
397 * if (index < array->len)
398 * retval = g_ptr_array_index (array, index);
399 * g_rw_lock_reader_unlock (&lock);
405 * my_array_set (guint index, gpointer data)
407 * g_rw_lock_writer_lock (&lock);
410 * array = g_ptr_array_new (<!-- -->);
412 * if (index >= array->len)
413 * g_ptr_array_set_size (array, index+1);
414 * g_ptr_array_index (array, index) = data;
416 * g_rw_lock_writer_unlock (&lock);
420 * This example shows an array which can be accessed by many readers
421 * (the <function>my_array_get()</function> function) simultaneously,
422 * whereas the writers (the <function>my_array_set()</function>
423 * function) will only be allowed once at a time and only if no readers
424 * currently access the array. This is because of the potentially
425 * dangerous resizing of the array. Using these functions is fully
426 * multi-thread safe now.
430 * A GRWLock should only be accessed with the
431 * <function>g_rw_lock_</function> functions. Before it can be used,
432 * it has to be initialized with #G_RW_LOCK_INIT or g_rw_lock_init().
440 * Initializer for statically allocated #GRWLocks.
441 * Alternatively, g_rw_lock_init_init() can be used.
444 * GRWLock lock = G_RW_LOCK_INIT;
450 /* GCond Documentation {{{1 ------------------------------------------ */
455 * The #GCond struct is an opaque data structure that represents a
456 * condition. Threads can block on a #GCond if they find a certain
457 * condition to be false. If other threads change the state of this
458 * condition they signal the #GCond, and that causes the waiting
459 * threads to be woken up.
463 * Using GCond to block a thread until a condition is satisfied
466 * GCond* data_cond = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
467 * GMutex* data_mutex = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
468 * gpointer current_data = NULL;
471 * push_data (gpointer data)
473 * g_mutex_lock (data_mutex);
474 * current_data = data;
475 * g_cond_signal (data_cond);
476 * g_mutex_unlock (data_mutex);
484 * g_mutex_lock (data_mutex);
485 * while (!current_data)
486 * g_cond_wait (data_cond, data_mutex);
487 * data = current_data;
488 * current_data = NULL;
489 * g_mutex_unlock (data_mutex);
496 * Whenever a thread calls pop_data() now, it will wait until
497 * current_data is non-%NULL, i.e. until some other thread
498 * has called push_data().
500 * <note><para>It is important to use the g_cond_wait() and
501 * g_cond_timed_wait() functions only inside a loop which checks for the
502 * condition to be true. It is not guaranteed that the waiting thread
503 * will find the condition fulfilled after it wakes up, even if the
504 * signaling thread left the condition in that state: another thread may
505 * have altered the condition before the waiting thread got the chance
506 * to be woken up, even if the condition itself is protected by a
507 * #GMutex, like above.</para></note>
509 * A #GCond should only be accessed via the <function>g_cond_</function>
516 * Initializer for statically allocated #GConds.
517 * Alternatively, g_cond_init() can be used.
520 * GCond cond = G_COND_INIT;
526 /* GPrivate Documentation {{{1 --------------------------------------- */
532 * #GStaticPrivate is a better choice for most uses.
535 * The #GPrivate struct is an opaque data structure to represent a
536 * thread private data key. Threads can thereby obtain and set a
537 * pointer which is private to the current thread. Take our
538 * <function>give_me_next_number(<!-- -->)</function> example from
539 * above. Suppose we don't want <literal>current_number</literal> to be
540 * shared between the threads, but instead to be private to each thread.
541 * This can be done as follows:
544 * <title>Using GPrivate for per-thread data</title>
546 * GPrivate* current_number_key = NULL; /<!-- -->* Must be initialized somewhere
547 * with g_private_new (g_free); *<!-- -->/
550 * give_me_next_number (void)
552 * int *current_number = g_private_get (current_number_key);
554 * if (!current_number)
556 * current_number = g_new (int, 1);
557 * *current_number = 0;
558 * g_private_set (current_number_key, current_number);
561 * *current_number = calc_next_number (*current_number);
563 * return *current_number;
568 * Here the pointer belonging to the key
569 * <literal>current_number_key</literal> is read. If it is %NULL, it has
570 * not been set yet. Then get memory for an integer value, assign this
571 * memory to the pointer and write the pointer back. Now we have an
572 * integer value that is private to the current thread.
574 * The #GPrivate struct should only be accessed via the
575 * <function>g_private_</function> functions.
578 /* GThread Documentation {{{1 ---------------------------------------- */
583 * The #GThread struct represents a running thread.
585 * Resources for a joinable thread are not fully released
586 * until g_thread_join() is called for that thread.
591 * @data: data passed to the thread
592 * @Returns: the return value of the thread, which will be returned by
595 * Specifies the type of the @func functions passed to
596 * g_thread_create() or g_thread_create_full().
600 * g_thread_supported:
602 * This macro returns %TRUE if the thread system is initialized,
603 * and %FALSE if it is not.
605 * For language bindings, g_thread_get_initialized() provides
606 * the same functionality as a function.
608 * Returns: %TRUE, if the thread system is initialized
611 /* GThreadError {{{1 ------------------------------------------------------- */
614 * @G_THREAD_ERROR_AGAIN: a thread couldn't be created due to resource
615 * shortage. Try again later.
617 * Possible errors of thread related functions.
623 * The error domain of the GLib thread subsystem.
626 g_thread_error_quark (void)
628 return g_quark_from_static_string ("g_thread_error");
631 /* Miscellaneous Structures {{{1 ------------------------------------------ */
633 typedef struct _GRealThread GRealThread;
637 GArray *private_data;
640 GSystemThread system_thread;
643 /* Local Data {{{1 -------------------------------------------------------- */
645 gboolean g_threads_got_initialized = FALSE;
646 GSystemThread zero_thread; /* This is initialized to all zero */
648 GMutex g_once_mutex = G_MUTEX_INIT;
649 static GCond g_once_cond = G_COND_INIT;
650 static GSList *g_once_init_list = NULL;
652 static GPrivate g_thread_specific_private;
653 static GRealThread *g_thread_all_threads = NULL;
654 static GSList *g_thread_free_indices = NULL;
656 /* Protects g_thread_all_threads and g_thread_free_indices */
657 G_LOCK_DEFINE_STATIC (g_thread);
659 /* Initialisation {{{1 ---------------------------------------------------- */
663 * @vtable: a function table of type #GThreadFunctions, that provides
664 * the entry points to the thread system to be used. Since 2.32,
665 * this parameter is ignored and should always be %NULL
667 * If you use GLib from more than one thread, you must initialize the
668 * thread system by calling g_thread_init().
670 * Since version 2.24, calling g_thread_init() multiple times is allowed,
671 * but nothing happens except for the first call.
673 * Since version 2.32, GLib does not support custom thread implementations
674 * anymore and the @vtable parameter is ignored and you should pass %NULL.
676 * <note><para>g_thread_init() must not be called directly or indirectly
677 * in a callback from GLib. Also no mutexes may be currently locked while
678 * calling g_thread_init().</para></note>
680 * <note><para>To use g_thread_init() in your program, you have to link
681 * with the libraries that the command <command>pkg-config --libs
682 * gthread-2.0</command> outputs. This is not the case for all the
683 * other thread-related functions of GLib. Those can be used without
684 * having to link with the thread libraries.</para></note>
687 static void g_thread_cleanup (gpointer data);
690 g_thread_init_glib (void)
692 static gboolean already_done;
693 GRealThread* main_thread;
700 /* We let the main thread (the one that calls g_thread_init) inherit
701 * the static_private data set before calling g_thread_init
703 main_thread = (GRealThread*) g_thread_self ();
705 /* setup the basic threading system */
706 g_threads_got_initialized = TRUE;
707 g_private_init (&g_thread_specific_private, g_thread_cleanup);
708 g_private_set (&g_thread_specific_private, main_thread);
709 g_system_thread_self (&main_thread->system_thread);
711 /* accomplish log system initialization to enable messaging */
712 _g_messages_thread_init_nomessage ();
716 * g_thread_get_initialized:
718 * Indicates if g_thread_init() has been called.
720 * Returns: %TRUE if threads have been initialized.
725 g_thread_get_initialized (void)
727 return g_thread_supported ();
730 /* GOnce {{{1 ------------------------------------------------------------- */
734 * @status: the status of the #GOnce
735 * @retval: the value returned by the call to the function, if @status
736 * is %G_ONCE_STATUS_READY
738 * A #GOnce struct controls a one-time initialization function. Any
739 * one-time initialization function must have its own unique #GOnce
748 * A #GOnce must be initialized with this macro before it can be used.
751 * GOnce my_once = G_ONCE_INIT;
759 * @G_ONCE_STATUS_NOTCALLED: the function has not been called yet.
760 * @G_ONCE_STATUS_PROGRESS: the function call is currently in progress.
761 * @G_ONCE_STATUS_READY: the function has been called.
763 * The possible statuses of a one-time initialization function
764 * controlled by a #GOnce struct.
771 * @once: a #GOnce structure
772 * @func: the #GThreadFunc function associated to @once. This function
773 * is called only once, regardless of the number of times it and
774 * its associated #GOnce struct are passed to g_once().
775 * @arg: data to be passed to @func
777 * The first call to this routine by a process with a given #GOnce
778 * struct calls @func with the given argument. Thereafter, subsequent
779 * calls to g_once() with the same #GOnce struct do not call @func
780 * again, but return the stored result of the first call. On return
781 * from g_once(), the status of @once will be %G_ONCE_STATUS_READY.
783 * For example, a mutex or a thread-specific data key must be created
784 * exactly once. In a threaded environment, calling g_once() ensures
785 * that the initialization is serialized across multiple threads.
787 * Calling g_once() recursively on the same #GOnce struct in
788 * @func will lead to a deadlock.
792 * get_debug_flags (void)
794 * static GOnce my_once = G_ONCE_INIT;
796 * g_once (&my_once, parse_debug_flags, NULL);
798 * return my_once.retval;
805 g_once_impl (GOnce *once,
809 g_mutex_lock (&g_once_mutex);
811 while (once->status == G_ONCE_STATUS_PROGRESS)
812 g_cond_wait (&g_once_cond, &g_once_mutex);
814 if (once->status != G_ONCE_STATUS_READY)
816 once->status = G_ONCE_STATUS_PROGRESS;
817 g_mutex_unlock (&g_once_mutex);
819 once->retval = func (arg);
821 g_mutex_lock (&g_once_mutex);
822 once->status = G_ONCE_STATUS_READY;
823 g_cond_broadcast (&g_once_cond);
826 g_mutex_unlock (&g_once_mutex);
833 * @value_location: location of a static initializable variable
836 * Function to be called when starting a critical initialization
837 * section. The argument @value_location must point to a static
838 * 0-initialized variable that will be set to a value other than 0 at
839 * the end of the initialization section. In combination with
840 * g_once_init_leave() and the unique address @value_location, it can
841 * be ensured that an initialization section will be executed only once
842 * during a program's life time, and that concurrent threads are
843 * blocked until initialization completed. To be used in constructs
847 * static gsize initialization_value = 0;
849 * if (g_once_init_enter (&initialization_value))
851 * gsize setup_value = 42; /** initialization code here **/
853 * g_once_init_leave (&initialization_value, setup_value);
856 * /** use initialization_value here **/
859 * Returns: %TRUE if the initialization section should be entered,
860 * %FALSE and blocks otherwise
865 g_once_init_enter_impl (volatile gsize *value_location)
867 gboolean need_init = FALSE;
868 g_mutex_lock (&g_once_mutex);
869 if (g_atomic_pointer_get (value_location) == NULL)
871 if (!g_slist_find (g_once_init_list, (void*) value_location))
874 g_once_init_list = g_slist_prepend (g_once_init_list, (void*) value_location);
878 g_cond_wait (&g_once_cond, &g_once_mutex);
879 while (g_slist_find (g_once_init_list, (void*) value_location));
881 g_mutex_unlock (&g_once_mutex);
887 * @value_location: location of a static initializable variable
889 * @initialization_value: new non-0 value for *@value_location
891 * Counterpart to g_once_init_enter(). Expects a location of a static
892 * 0-initialized initialization variable, and an initialization value
893 * other than 0. Sets the variable to the initialization value, and
894 * releases concurrent threads blocking in g_once_init_enter() on this
895 * initialization variable.
900 g_once_init_leave (volatile gsize *value_location,
901 gsize initialization_value)
903 g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
904 g_return_if_fail (initialization_value != 0);
905 g_return_if_fail (g_once_init_list != NULL);
907 g_atomic_pointer_set (value_location, initialization_value);
908 g_mutex_lock (&g_once_mutex);
909 g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
910 g_cond_broadcast (&g_once_cond);
911 g_mutex_unlock (&g_once_mutex);
914 /* GStaticPrivate {{{1 ---------------------------------------------------- */
916 typedef struct _GStaticPrivateNode GStaticPrivateNode;
917 struct _GStaticPrivateNode
920 GDestroyNotify destroy;
921 GStaticPrivate *owner;
927 * A #GStaticPrivate works almost like a #GPrivate, but it has one
928 * significant advantage. It doesn't need to be created at run-time
929 * like a #GPrivate, but can be defined at compile-time. This is
930 * similar to the difference between #GMutex and #GStaticMutex. Now
931 * look at our <function>give_me_next_number()</function> example with
935 * <title>Using GStaticPrivate for per-thread data</title>
938 * give_me_next_number (<!-- -->)
940 * static GStaticPrivate current_number_key = G_STATIC_PRIVATE_INIT;
941 * int *current_number = g_static_private_get (&current_number_key);
943 * if (!current_number)
945 * current_number = g_new (int,1);
946 * *current_number = 0;
947 * g_static_private_set (&current_number_key, current_number, g_free);
950 * *current_number = calc_next_number (*current_number);
952 * return *current_number;
959 * G_STATIC_PRIVATE_INIT:
961 * Every #GStaticPrivate must be initialized with this macro, before it
965 * GStaticPrivate my_private = G_STATIC_PRIVATE_INIT;
970 * g_static_private_init:
971 * @private_key: a #GStaticPrivate to be initialized
973 * Initializes @private_key. Alternatively you can initialize it with
974 * #G_STATIC_PRIVATE_INIT.
977 g_static_private_init (GStaticPrivate *private_key)
979 private_key->index = 0;
983 * g_static_private_get:
984 * @private_key: a #GStaticPrivate
986 * Works like g_private_get() only for a #GStaticPrivate.
988 * This function works even if g_thread_init() has not yet been called.
990 * Returns: the corresponding pointer
993 g_static_private_get (GStaticPrivate *private_key)
995 GRealThread *self = (GRealThread*) g_thread_self ();
999 array = self->private_data;
1001 if (array && private_key->index != 0 && private_key->index <= array->len)
1003 GStaticPrivateNode *node;
1005 node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
1007 /* Deal with the possibility that the GStaticPrivate which used
1008 * to have this index got freed and the index got allocated to
1009 * a new one. In this case, the data in the node is stale, so
1010 * free it and return NULL.
1012 if (G_UNLIKELY (node->owner != private_key))
1015 node->destroy (node->data);
1016 node->destroy = NULL;
1028 * g_static_private_set:
1029 * @private_key: a #GStaticPrivate
1030 * @data: the new pointer
1031 * @notify: a function to be called with the pointer whenever the
1032 * current thread ends or sets this pointer again
1034 * Sets the pointer keyed to @private_key for the current thread and
1035 * the function @notify to be called with that pointer (%NULL or
1036 * non-%NULL), whenever the pointer is set again or whenever the
1037 * current thread ends.
1039 * This function works even if g_thread_init() has not yet been called.
1040 * If g_thread_init() is called later, the @data keyed to @private_key
1041 * will be inherited only by the main thread, i.e. the one that called
1044 * <note><para>@notify is used quite differently from @destructor in
1045 * g_private_new().</para></note>
1048 g_static_private_set (GStaticPrivate *private_key,
1050 GDestroyNotify notify)
1052 GRealThread *self = (GRealThread*) g_thread_self ();
1054 static guint next_index = 0;
1055 GStaticPrivateNode *node;
1057 if (!private_key->index)
1061 if (!private_key->index)
1063 if (g_thread_free_indices)
1065 private_key->index = GPOINTER_TO_UINT (g_thread_free_indices->data);
1066 g_thread_free_indices = g_slist_delete_link (g_thread_free_indices,
1067 g_thread_free_indices);
1070 private_key->index = ++next_index;
1073 G_UNLOCK (g_thread);
1076 array = self->private_data;
1079 array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
1080 self->private_data = array;
1083 if (private_key->index > array->len)
1084 g_array_set_size (array, private_key->index);
1086 node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
1089 node->destroy (node->data);
1092 node->destroy = notify;
1093 node->owner = private_key;
1097 * g_static_private_free:
1098 * @private_key: a #GStaticPrivate to be freed
1100 * Releases all resources allocated to @private_key.
1102 * You don't have to call this functions for a #GStaticPrivate with an
1103 * unbounded lifetime, i.e. objects declared 'static', but if you have
1104 * a #GStaticPrivate as a member of a structure and the structure is
1105 * freed, you should also free the #GStaticPrivate.
1108 g_static_private_free (GStaticPrivate *private_key)
1110 guint idx = private_key->index;
1115 private_key->index = 0;
1117 /* Freeing the per-thread data is deferred to either the
1118 * thread end or the next g_static_private_get() call for
1122 g_thread_free_indices = g_slist_prepend (g_thread_free_indices,
1123 GUINT_TO_POINTER (idx));
1124 G_UNLOCK (g_thread);
1127 /* GThread {{{1 -------------------------------------------------------- */
1130 g_thread_cleanup (gpointer data)
1134 GRealThread* thread = data;
1137 array = thread->private_data;
1138 thread->private_data = NULL;
1144 for (i = 0; i < array->len; i++ )
1146 GStaticPrivateNode *node = &g_array_index (array, GStaticPrivateNode, i);
1148 node->destroy (node->data);
1150 g_array_free (array, TRUE);
1153 /* We only free the thread structure if it isn't joinable.
1154 * If it is, the structure is freed in g_thread_join()
1156 if (!thread->thread.joinable)
1161 for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
1168 g_thread_all_threads = t->next;
1172 G_UNLOCK (g_thread);
1174 /* Just to make sure, this isn't used any more */
1175 g_system_thread_assign (thread->system_thread, zero_thread);
1182 g_thread_create_proxy (gpointer data)
1184 GRealThread* thread = data;
1188 /* This has to happen before G_LOCK, as that might call g_thread_self */
1189 g_private_set (&g_thread_specific_private, data);
1191 /* The lock makes sure that thread->system_thread is written,
1192 * before thread->thread.func is called. See g_thread_create().
1195 G_UNLOCK (g_thread);
1197 thread->retval = thread->thread.func (thread->thread.data);
1204 * @func: a function to execute in the new thread
1205 * @data: an argument to supply to the new thread
1206 * @joinable: should this thread be joinable?
1207 * @error: return location for error, or %NULL
1209 * This function creates a new thread.
1211 * If @joinable is %TRUE, you can wait for this threads termination
1212 * calling g_thread_join(). Otherwise the thread will just disappear
1213 * when it terminates.
1215 * The new thread executes the function @func with the argument @data.
1216 * If the thread was created successfully, it is returned.
1218 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
1219 * The error is set, if and only if the function returns %NULL.
1221 * Returns: the new #GThread on success
1224 g_thread_create (GThreadFunc func,
1229 return g_thread_create_with_stack_size (func, data, joinable, 0, error);
1233 * g_thread_create_with_stack_size:
1234 * @func: a function to execute in the new thread
1235 * @data: an argument to supply to the new thread
1236 * @joinable: should this thread be joinable?
1237 * @stack_size: a stack size for the new thread
1238 * @error: return location for error
1240 * This function creates a new thread. If the underlying thread
1241 * implementation supports it, the thread gets a stack size of
1242 * @stack_size or the default value for the current platform, if
1245 * If @joinable is %TRUE, you can wait for this threads termination
1246 * calling g_thread_join(). Otherwise the thread will just disappear
1247 * when it terminates.
1249 * The new thread executes the function @func with the argument @data.
1250 * If the thread was created successfully, it is returned.
1252 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
1253 * The error is set, if and only if the function returns %NULL.
1255 * <note><para>Only use g_thread_create_with_stack_size() if you
1256 * really can't use g_thread_create() instead. g_thread_create()
1257 * does not take @stack_size, as it should only be used in cases
1258 * in which it is unavoidable.</para></note>
1260 * Returns: the new #GThread on success
1265 g_thread_create_with_stack_size (GThreadFunc func,
1271 GRealThread* result;
1272 GError *local_error = NULL;
1273 g_return_val_if_fail (func, NULL);
1275 result = g_new0 (GRealThread, 1);
1277 result->thread.joinable = joinable;
1278 result->thread.func = func;
1279 result->thread.data = data;
1280 result->private_data = NULL;
1282 g_system_thread_create (g_thread_create_proxy, result,
1283 stack_size, joinable,
1284 &result->system_thread, &local_error);
1287 result->next = g_thread_all_threads;
1288 g_thread_all_threads = result;
1290 G_UNLOCK (g_thread);
1294 g_propagate_error (error, local_error);
1299 return (GThread*) result;
1304 * @retval: the return value of this thread
1306 * Exits the current thread. If another thread is waiting for that
1307 * thread using g_thread_join() and the current thread is joinable, the
1308 * waiting thread will be woken up and get @retval as the return value
1309 * of g_thread_join(). If the current thread is not joinable, @retval
1310 * is ignored. Calling
1313 * g_thread_exit (retval);
1316 * is equivalent to returning @retval from the function @func, as given
1317 * to g_thread_create().
1319 * <note><para>Never call g_thread_exit() from within a thread of a
1320 * #GThreadPool, as that will mess up the bookkeeping and lead to funny
1321 * and unwanted results.</para></note>
1324 g_thread_exit (gpointer retval)
1326 GRealThread* real = (GRealThread*) g_thread_self ();
1327 real->retval = retval;
1329 g_system_thread_exit ();
1334 * @thread: a #GThread to be waited for
1336 * Waits until @thread finishes, i.e. the function @func, as given to
1337 * g_thread_create(), returns or g_thread_exit() is called by @thread.
1338 * All resources of @thread including the #GThread struct are released.
1339 * @thread must have been created with @joinable=%TRUE in
1340 * g_thread_create(). The value returned by @func or given to
1341 * g_thread_exit() by @thread is returned by this function.
1343 * Returns: the return value of the thread
1346 g_thread_join (GThread* thread)
1348 GRealThread* real = (GRealThread*) thread;
1352 g_return_val_if_fail (thread, NULL);
1353 g_return_val_if_fail (thread->joinable, NULL);
1354 g_return_val_if_fail (!g_system_thread_equal (&real->system_thread, &zero_thread), NULL);
1356 g_system_thread_join (&real->system_thread);
1358 retval = real->retval;
1361 for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
1363 if (t == (GRealThread*) thread)
1368 g_thread_all_threads = t->next;
1372 G_UNLOCK (g_thread);
1374 /* Just to make sure, this isn't used any more */
1375 thread->joinable = 0;
1376 g_system_thread_assign (real->system_thread, zero_thread);
1378 /* the thread structure for non-joinable threads is freed upon
1379 * thread end. We free the memory here. This will leave a loose end,
1380 * if a joinable thread is not joined.
1390 * This functions returns the #GThread corresponding to the calling
1393 * Returns: the current thread
1396 g_thread_self (void)
1398 GRealThread* thread = g_private_get (&g_thread_specific_private);
1402 /* If no thread data is available, provide and set one.
1403 * This can happen for the main thread and for threads
1404 * that are not created by GLib.
1406 thread = g_new0 (GRealThread, 1);
1407 thread->thread.joinable = FALSE; /* This is a safe guess */
1408 thread->thread.func = NULL;
1409 thread->thread.data = NULL;
1410 thread->private_data = NULL;
1412 g_system_thread_self (&thread->system_thread);
1414 g_private_set (&g_thread_specific_private, thread);
1417 thread->next = g_thread_all_threads;
1418 g_thread_all_threads = thread;
1419 G_UNLOCK (g_thread);
1422 return (GThread*)thread;
1427 * @thread_func: function to call for all #GThread structures
1428 * @user_data: second argument to @thread_func
1430 * Call @thread_func on all existing #GThread structures.
1431 * Note that threads may decide to exit while @thread_func is
1432 * running, so without intimate knowledge about the lifetime of
1433 * foreign threads, @thread_func shouldn't access the GThread*
1434 * pointer passed in as first argument. However, @thread_func will
1435 * not be called for threads which are known to have exited already.
1437 * Due to thread lifetime checks, this function has an execution complexity
1438 * which is quadratic in the number of existing threads.
1443 g_thread_foreach (GFunc thread_func,
1446 GSList *slist = NULL;
1447 GRealThread *thread;
1448 g_return_if_fail (thread_func != NULL);
1449 /* snapshot the list of threads for iteration */
1451 for (thread = g_thread_all_threads; thread; thread = thread->next)
1452 slist = g_slist_prepend (slist, thread);
1453 G_UNLOCK (g_thread);
1454 /* walk the list, skipping non-existent threads */
1457 GSList *node = slist;
1459 /* check whether the current thread still exists */
1461 for (thread = g_thread_all_threads; thread; thread = thread->next)
1462 if (thread == node->data)
1464 G_UNLOCK (g_thread);
1466 thread_func (thread, user_data);
1467 g_slist_free_1 (node);
1471 /* GMutex {{{1 ------------------------------------------------------ */
1476 * Allocated and initializes a new #GMutex.
1478 * Returns: a newly allocated #GMutex. Use g_mutex_free() to free
1485 mutex = g_slice_new (GMutex);
1486 g_mutex_init (mutex);
1495 * Destroys a @mutex that has been created with g_mutex_new().
1497 * Calling g_mutex_free() on a locked mutex may result
1498 * in undefined behaviour.
1501 g_mutex_free (GMutex *mutex)
1503 g_mutex_clear (mutex);
1504 g_slice_free (GMutex, mutex);
1507 /* GCond {{{1 ------------------------------------------------------ */
1512 * Allocates and initializes a new #GCond.
1514 * Returns: a newly allocated #GCond. Free with g_cond_free()
1521 cond = g_slice_new (GCond);
1531 * Destroys a #GCond that has been created with g_cond_new().
1534 g_cond_free (GCond *cond)
1536 g_cond_clear (cond);
1537 g_slice_free (GCond, cond);
1540 /* GPrivate {{{1 ------------------------------------------------------ */
1544 * @destructor: a function to destroy the data keyed to
1545 * the #GPrivate when a thread ends
1547 * Creates a new #GPrivate. If @destructor is non-%NULL, it is a
1548 * pointer to a destructor function. Whenever a thread ends and the
1549 * corresponding pointer keyed to this instance of #GPrivate is
1550 * non-%NULL, the destructor is called with this pointer as the
1554 * #GStaticPrivate is a better choice for most uses.
1557 * <note><para>@destructor is used quite differently from @notify in
1558 * g_static_private_set().</para></note>
1560 * <note><para>A #GPrivate cannot be freed. Reuse it instead, if you
1561 * can, to avoid shortage, or use #GStaticPrivate.</para></note>
1563 * <note><para>This function will abort if g_thread_init() has not been
1564 * called yet.</para></note>
1566 * Returns: a newly allocated #GPrivate
1569 g_private_new (GDestroyNotify notify)
1573 key = g_slice_new (GPrivate);
1574 g_private_init (key, notify);
1579 /* vim: set foldmethod=marker: */