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"
59 #endif /* G_OS_WIN32 */
66 #include "gtestutils.h"
72 * @short_description: portable support for threads, mutexes, locks,
73 * conditions and thread private data
74 * @see_also: #GThreadPool, #GAsyncQueue
76 * Threads act almost like processes, but unlike processes all threads
77 * of one process share the same memory. This is good, as it provides
78 * easy communication between the involved threads via this shared
79 * memory, and it is bad, because strange things (so called
80 * "Heisenbugs") might happen if the program is not carefully designed.
81 * In particular, due to the concurrent nature of threads, no
82 * assumptions on the order of execution of code running in different
83 * threads can be made, unless order is explicitly forced by the
84 * programmer through synchronization primitives.
86 * The aim of the thread-related functions in GLib is to provide a
87 * portable means for writing multi-threaded software. There are
88 * primitives for mutexes to protect the access to portions of memory
89 * (#GMutex, #GRecMutex and #GRWLock). There is a facility to use
90 * individual bits for locks (g_bit_lock()). There are primitives
91 * for condition variables to allow synchronization of threads (#GCond).
92 * There are primitives for thread-private data - data that every thread
93 * has a private instance of (#GPrivate, #GStaticPrivate). There are
94 * facilities for one-time initialization (#GOnce, g_once_init_enter()).
95 * Finally there are primitives to create and manage threads (#GThread).
97 * The threading system is initialized with g_thread_init().
98 * You may call any other glib functions in the main thread before
99 * g_thread_init() as long as g_thread_init() is not called from
100 * a GLib callback, or with any locks held. However, many libraries
101 * above GLib does not support late initialization of threads, so
102 * doing this should be avoided if possible.
104 * Please note that since version 2.24 the GObject initialization
105 * function g_type_init() initializes threads. Since 2.32, creating
106 * a mainloop will do so too. As a consequence, most applications,
107 * including those using GTK+ will run with threads enabled.
109 * After calling g_thread_init(), GLib is completely thread safe
110 * (all global data is automatically locked), but individual data
111 * structure instances are not automatically locked for performance
112 * reasons. So, for example you must coordinate accesses to the same
113 * #GHashTable from multiple threads. The two notable exceptions from
114 * this rule are #GMainLoop and #GAsyncQueue, which <emphasis>are</emphasis>
115 * threadsafe and need no further application-level locking to be
116 * accessed from multiple threads.
120 * G_THREADS_IMPL_POSIX:
122 * This macro is defined if POSIX style threads are used.
126 * G_THREADS_IMPL_WIN32:
128 * This macro is defined if Windows style threads are used.
131 /* G_LOCK Documentation {{{1 ---------------------------------------------- */
135 * @name: the name of the lock.
137 * The %G_LOCK_* macros provide a convenient interface to #GMutex
138 * with the advantage that they will expand to nothing in programs
139 * compiled against a thread-disabled GLib, saving code and memory
140 * there. #G_LOCK_DEFINE defines a lock. It can appear anywhere
141 * variable definitions may appear in programs, i.e. in the first block
142 * of a function or outside of functions. The @name parameter will be
143 * mangled to get the name of the #GMutex. This means that you
144 * can use names of existing variables as the parameter - e.g. the name
145 * of the variable you intent to protect with the lock. Look at our
146 * <function>give_me_next_number()</function> example using the
150 * <title>Using the %G_LOCK_* convenience macros</title>
152 * G_LOCK_DEFINE (current_number);
155 * give_me_next_number (void)
157 * static int current_number = 0;
160 * G_LOCK (current_number);
161 * ret_val = current_number = calc_next_number (current_number);
162 * G_UNLOCK (current_number);
171 * G_LOCK_DEFINE_STATIC:
172 * @name: the name of the lock.
174 * This works like #G_LOCK_DEFINE, but it creates a static object.
179 * @name: the name of the lock.
181 * This declares a lock, that is defined with #G_LOCK_DEFINE in another
187 * @name: the name of the lock.
189 * Works like g_mutex_lock(), but for a lock defined with
195 * @name: the name of the lock.
196 * @Returns: %TRUE, if the lock could be locked.
198 * Works like g_mutex_trylock(), but for a lock defined with
204 * @name: the name of the lock.
206 * Works like g_mutex_unlock(), but for a lock defined with
210 /* GMutex Documentation {{{1 ------------------------------------------ */
215 * The #GMutex struct is an opaque data structure to represent a mutex
216 * (mutual exclusion). It can be used to protect data against shared
217 * access. Take for example the following function:
220 * <title>A function which will not work in a threaded environment</title>
223 * give_me_next_number (void)
225 * static int current_number = 0;
227 * /<!-- -->* now do a very complicated calculation to calculate the new
228 * * number, this might for example be a random number generator
230 * current_number = calc_next_number (current_number);
232 * return current_number;
237 * It is easy to see that this won't work in a multi-threaded
238 * application. There current_number must be protected against shared
239 * access. A first naive implementation would be:
242 * <title>The wrong way to write a thread-safe function</title>
245 * give_me_next_number (void)
247 * static int current_number = 0;
249 * static GMutex * mutex = NULL;
251 * if (!mutex) mutex = g_mutex_new (<!-- -->);
253 * g_mutex_lock (mutex);
254 * ret_val = current_number = calc_next_number (current_number);
255 * g_mutex_unlock (mutex);
262 * This looks like it would work, but there is a race condition while
263 * constructing the mutex and this code cannot work reliable. Please do
264 * not use such constructs in your own programs! One working solution
268 * <title>A correct thread-safe function</title>
270 * static GMutex *give_me_next_number_mutex = NULL;
272 * /<!-- -->* this function must be called before any call to
273 * * give_me_next_number(<!-- -->)
275 * * it must be called exactly once.
278 * init_give_me_next_number (void)
280 * g_assert (give_me_next_number_mutex == NULL);
281 * give_me_next_number_mutex = g_mutex_new (<!-- -->);
285 * give_me_next_number (void)
287 * static int current_number = 0;
290 * g_mutex_lock (give_me_next_number_mutex);
291 * ret_val = current_number = calc_next_number (current_number);
292 * g_mutex_unlock (give_me_next_number_mutex);
299 * A statically initialized #GMutex provides an even simpler and safer
303 * <title>Using a statically allocated mutex</title>
306 * give_me_next_number (void)
308 * static GMutex mutex = G_MUTEX_INIT;
309 * static int current_number = 0;
312 * g_mutex_lock (&mutex);
313 * ret_val = current_number = calc_next_number (current_number);
314 * g_mutex_unlock (&mutex);
321 * A #GMutex should only be accessed via <function>g_mutex_</function>
328 * Initializer for statically allocated #GMutexes.
329 * Alternatively, g_mutex_init() can be used.
332 * GMutex mutex = G_MUTEX_INIT;
338 /* GRecMutex Documentation {{{1 -------------------------------------- */
343 * The GRecMutex struct is an opaque data structure to represent a
344 * recursive mutex. It is similar to a #GMutex with the difference
345 * that it is possible to lock a GRecMutex multiple times in the same
346 * thread without deadlock. When doing so, care has to be taken to
347 * unlock the recursive mutex as often as it has been locked.
349 * A GRecMutex should only be accessed with the
350 * <function>g_rec_mutex_</function> functions. Before a GRecMutex
351 * can be used, it has to be initialized with #G_REC_MUTEX_INIT or
352 * g_rec_mutex_init().
360 * Initializer for statically allocated #GRecMutexes.
361 * Alternatively, g_rec_mutex_init() can be used.
364 * GRecMutex mutex = G_REC_MUTEX_INIT;
370 /* GRWLock Documentation {{{1 ---------------------------------------- */
375 * The GRWLock struct is an opaque data structure to represent a
376 * reader-writer lock. It is similar to a #GMutex in that it allows
377 * multiple threads to coordinate access to a shared resource.
379 * The difference to a mutex is that a reader-writer lock discriminates
380 * between read-only ('reader') and full ('writer') access. While only
381 * one thread at a time is allowed write access (by holding the 'writer'
382 * lock via g_rw_lock_writer_lock()), multiple threads can gain
383 * simultaneous read-only access (by holding the 'reader' lock via
384 * g_rw_lock_reader_lock()).
387 * <title>An array with access functions</title>
389 * GRWLock lock = G_RW_LOCK_INIT;
393 * my_array_get (guint index)
395 * gpointer retval = NULL;
400 * g_rw_lock_reader_lock (&lock);
401 * if (index < array->len)
402 * retval = g_ptr_array_index (array, index);
403 * g_rw_lock_reader_unlock (&lock);
409 * my_array_set (guint index, gpointer data)
411 * g_rw_lock_writer_lock (&lock);
414 * array = g_ptr_array_new (<!-- -->);
416 * if (index >= array->len)
417 * g_ptr_array_set_size (array, index+1);
418 * g_ptr_array_index (array, index) = data;
420 * g_rw_lock_writer_unlock (&lock);
424 * This example shows an array which can be accessed by many readers
425 * (the <function>my_array_get()</function> function) simultaneously,
426 * whereas the writers (the <function>my_array_set()</function>
427 * function) will only be allowed once at a time and only if no readers
428 * currently access the array. This is because of the potentially
429 * dangerous resizing of the array. Using these functions is fully
430 * multi-thread safe now.
434 * A GRWLock should only be accessed with the
435 * <function>g_rw_lock_</function> functions. Before it can be used,
436 * it has to be initialized with #G_RW_LOCK_INIT or g_rw_lock_init().
444 * Initializer for statically allocated #GRWLocks.
445 * Alternatively, g_rw_lock_init_init() can be used.
448 * GRWLock lock = G_RW_LOCK_INIT;
454 /* GCond Documentation {{{1 ------------------------------------------ */
459 * The #GCond struct is an opaque data structure that represents a
460 * condition. Threads can block on a #GCond if they find a certain
461 * condition to be false. If other threads change the state of this
462 * condition they signal the #GCond, and that causes the waiting
463 * threads to be woken up.
467 * Using GCond to block a thread until a condition is satisfied
470 * GCond* data_cond = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
471 * GMutex* data_mutex = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
472 * gpointer current_data = NULL;
475 * push_data (gpointer data)
477 * g_mutex_lock (data_mutex);
478 * current_data = data;
479 * g_cond_signal (data_cond);
480 * g_mutex_unlock (data_mutex);
488 * g_mutex_lock (data_mutex);
489 * while (!current_data)
490 * g_cond_wait (data_cond, data_mutex);
491 * data = current_data;
492 * current_data = NULL;
493 * g_mutex_unlock (data_mutex);
500 * Whenever a thread calls pop_data() now, it will wait until
501 * current_data is non-%NULL, i.e. until some other thread
502 * has called push_data().
504 * <note><para>It is important to use the g_cond_wait() and
505 * g_cond_timed_wait() functions only inside a loop which checks for the
506 * condition to be true. It is not guaranteed that the waiting thread
507 * will find the condition fulfilled after it wakes up, even if the
508 * signaling thread left the condition in that state: another thread may
509 * have altered the condition before the waiting thread got the chance
510 * to be woken up, even if the condition itself is protected by a
511 * #GMutex, like above.</para></note>
513 * A #GCond should only be accessed via the <function>g_cond_</function>
520 * Initializer for statically allocated #GConds.
521 * Alternatively, g_cond_init() can be used.
524 * GCond cond = G_COND_INIT;
530 /* GPrivate Documentation {{{1 --------------------------------------- */
536 * #GStaticPrivate is a better choice for most uses.
539 * The #GPrivate struct is an opaque data structure to represent a
540 * thread private data key. Threads can thereby obtain and set a
541 * pointer which is private to the current thread. Take our
542 * <function>give_me_next_number(<!-- -->)</function> example from
543 * above. Suppose we don't want <literal>current_number</literal> to be
544 * shared between the threads, but instead to be private to each thread.
545 * This can be done as follows:
548 * <title>Using GPrivate for per-thread data</title>
550 * GPrivate* current_number_key = NULL; /<!-- -->* Must be initialized somewhere
551 * with g_private_new (g_free); *<!-- -->/
554 * give_me_next_number (void)
556 * int *current_number = g_private_get (current_number_key);
558 * if (!current_number)
560 * current_number = g_new (int, 1);
561 * *current_number = 0;
562 * g_private_set (current_number_key, current_number);
565 * *current_number = calc_next_number (*current_number);
567 * return *current_number;
572 * Here the pointer belonging to the key
573 * <literal>current_number_key</literal> is read. If it is %NULL, it has
574 * not been set yet. Then get memory for an integer value, assign this
575 * memory to the pointer and write the pointer back. Now we have an
576 * integer value that is private to the current thread.
578 * The #GPrivate struct should only be accessed via the
579 * <function>g_private_</function> functions.
582 /* GThread Documentation {{{1 ---------------------------------------- */
587 * The #GThread struct represents a running thread.
589 * Resources for a joinable thread are not fully released
590 * until g_thread_join() is called for that thread.
595 * @data: data passed to the thread
596 * @Returns: the return value of the thread, which will be returned by
599 * Specifies the type of the @func functions passed to
600 * g_thread_create() or g_thread_create_full().
604 * g_thread_supported:
606 * This macro returns %TRUE if the thread system is initialized,
607 * and %FALSE if it is not.
609 * For language bindings, g_thread_get_initialized() provides
610 * the same functionality as a function.
612 * Returns: %TRUE, if the thread system is initialized
615 /* GThreadError {{{1 ------------------------------------------------------- */
618 * @G_THREAD_ERROR_AGAIN: a thread couldn't be created due to resource
619 * shortage. Try again later.
621 * Possible errors of thread related functions.
627 * The error domain of the GLib thread subsystem.
630 g_thread_error_quark (void)
632 return g_quark_from_static_string ("g_thread_error");
635 /* Miscellaneous Structures {{{1 ------------------------------------------ */
637 typedef struct _GRealThread GRealThread;
641 /* Bit 0 protects private_data. To avoid deadlocks,
642 * do not block while holding this (particularly on
643 * the g_thread lock).
645 volatile gint private_data_lock;
646 GArray *private_data;
649 GSystemThread system_thread;
652 #define LOCK_PRIVATE_DATA(self) g_bit_lock (&(self)->private_data_lock, 0)
653 #define UNLOCK_PRIVATE_DATA(self) g_bit_unlock (&(self)->private_data_lock, 0)
655 /* Local Data {{{1 -------------------------------------------------------- */
657 gboolean g_threads_got_initialized = FALSE;
658 GSystemThread zero_thread; /* This is initialized to all zero */
659 GMutex g_once_mutex = G_MUTEX_INIT;
661 static GCond g_once_cond = G_COND_INIT;
662 static GPrivate g_thread_specific_private;
663 static GRealThread *g_thread_all_threads = NULL;
664 static GSList *g_thread_free_indices = NULL;
665 static GSList* g_once_init_list = NULL;
667 G_LOCK_DEFINE_STATIC (g_thread);
669 /* Initialisation {{{1 ---------------------------------------------------- */
673 * @vtable: a function table of type #GThreadFunctions, that provides
674 * the entry points to the thread system to be used. Since 2.32,
675 * this parameter is ignored and should always be %NULL
677 * If you use GLib from more than one thread, you must initialize the
678 * thread system by calling g_thread_init().
680 * Since version 2.24, calling g_thread_init() multiple times is allowed,
681 * but nothing happens except for the first call.
683 * Since version 2.32, GLib does not support custom thread implementations
684 * anymore and the @vtable parameter is ignored and you should pass %NULL.
686 * <note><para>g_thread_init() must not be called directly or indirectly
687 * in a callback from GLib. Also no mutexes may be currently locked while
688 * calling g_thread_init().</para></note>
690 * <note><para>To use g_thread_init() in your program, you have to link
691 * with the libraries that the command <command>pkg-config --libs
692 * gthread-2.0</command> outputs. This is not the case for all the
693 * other thread-related functions of GLib. Those can be used without
694 * having to link with the thread libraries.</para></note>
697 static void g_thread_cleanup (gpointer data);
700 g_thread_init_glib (void)
702 static gboolean already_done;
703 GRealThread* main_thread;
710 /* We let the main thread (the one that calls g_thread_init) inherit
711 * the static_private data set before calling g_thread_init
713 main_thread = (GRealThread*) g_thread_self ();
715 /* setup the basic threading system */
716 g_threads_got_initialized = TRUE;
717 g_private_init (&g_thread_specific_private, g_thread_cleanup);
718 g_private_set (&g_thread_specific_private, main_thread);
719 g_system_thread_self (&main_thread->system_thread);
721 /* accomplish log system initialization to enable messaging */
722 _g_messages_thread_init_nomessage ();
726 * g_thread_get_initialized:
728 * Indicates if g_thread_init() has been called.
730 * Returns: %TRUE if threads have been initialized.
735 g_thread_get_initialized (void)
737 return g_thread_supported ();
740 /* GOnce {{{1 ------------------------------------------------------------- */
744 * @status: the status of the #GOnce
745 * @retval: the value returned by the call to the function, if @status
746 * is %G_ONCE_STATUS_READY
748 * A #GOnce struct controls a one-time initialization function. Any
749 * one-time initialization function must have its own unique #GOnce
758 * A #GOnce must be initialized with this macro before it can be used.
761 * GOnce my_once = G_ONCE_INIT;
769 * @G_ONCE_STATUS_NOTCALLED: the function has not been called yet.
770 * @G_ONCE_STATUS_PROGRESS: the function call is currently in progress.
771 * @G_ONCE_STATUS_READY: the function has been called.
773 * The possible statuses of a one-time initialization function
774 * controlled by a #GOnce struct.
781 * @once: a #GOnce structure
782 * @func: the #GThreadFunc function associated to @once. This function
783 * is called only once, regardless of the number of times it and
784 * its associated #GOnce struct are passed to g_once().
785 * @arg: data to be passed to @func
787 * The first call to this routine by a process with a given #GOnce
788 * struct calls @func with the given argument. Thereafter, subsequent
789 * calls to g_once() with the same #GOnce struct do not call @func
790 * again, but return the stored result of the first call. On return
791 * from g_once(), the status of @once will be %G_ONCE_STATUS_READY.
793 * For example, a mutex or a thread-specific data key must be created
794 * exactly once. In a threaded environment, calling g_once() ensures
795 * that the initialization is serialized across multiple threads.
797 * Calling g_once() recursively on the same #GOnce struct in
798 * @func will lead to a deadlock.
802 * get_debug_flags (void)
804 * static GOnce my_once = G_ONCE_INIT;
806 * g_once (&my_once, parse_debug_flags, NULL);
808 * return my_once.retval;
815 g_once_impl (GOnce *once,
819 g_mutex_lock (&g_once_mutex);
821 while (once->status == G_ONCE_STATUS_PROGRESS)
822 g_cond_wait (&g_once_cond, &g_once_mutex);
824 if (once->status != G_ONCE_STATUS_READY)
826 once->status = G_ONCE_STATUS_PROGRESS;
827 g_mutex_unlock (&g_once_mutex);
829 once->retval = func (arg);
831 g_mutex_lock (&g_once_mutex);
832 once->status = G_ONCE_STATUS_READY;
833 g_cond_broadcast (&g_once_cond);
836 g_mutex_unlock (&g_once_mutex);
843 * @value_location: location of a static initializable variable
846 * Function to be called when starting a critical initialization
847 * section. The argument @value_location must point to a static
848 * 0-initialized variable that will be set to a value other than 0 at
849 * the end of the initialization section. In combination with
850 * g_once_init_leave() and the unique address @value_location, it can
851 * be ensured that an initialization section will be executed only once
852 * during a program's life time, and that concurrent threads are
853 * blocked until initialization completed. To be used in constructs
857 * static gsize initialization_value = 0;
859 * if (g_once_init_enter (&initialization_value))
861 * gsize setup_value = 42; /** initialization code here **/
863 * g_once_init_leave (&initialization_value, setup_value);
866 * /** use initialization_value here **/
869 * Returns: %TRUE if the initialization section should be entered,
870 * %FALSE and blocks otherwise
875 g_once_init_enter_impl (volatile gsize *value_location)
877 gboolean need_init = FALSE;
878 g_mutex_lock (&g_once_mutex);
879 if (g_atomic_pointer_get (value_location) == NULL)
881 if (!g_slist_find (g_once_init_list, (void*) value_location))
884 g_once_init_list = g_slist_prepend (g_once_init_list, (void*) value_location);
888 g_cond_wait (&g_once_cond, &g_once_mutex);
889 while (g_slist_find (g_once_init_list, (void*) value_location));
891 g_mutex_unlock (&g_once_mutex);
897 * @value_location: location of a static initializable variable
899 * @initialization_value: new non-0 value for *@value_location
901 * Counterpart to g_once_init_enter(). Expects a location of a static
902 * 0-initialized initialization variable, and an initialization value
903 * other than 0. Sets the variable to the initialization value, and
904 * releases concurrent threads blocking in g_once_init_enter() on this
905 * initialization variable.
910 g_once_init_leave (volatile gsize *value_location,
911 gsize initialization_value)
913 g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
914 g_return_if_fail (initialization_value != 0);
915 g_return_if_fail (g_once_init_list != NULL);
917 g_atomic_pointer_set (value_location, initialization_value);
918 g_mutex_lock (&g_once_mutex);
919 g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
920 g_cond_broadcast (&g_once_cond);
921 g_mutex_unlock (&g_once_mutex);
924 /* GStaticPrivate {{{1 ---------------------------------------------------- */
926 typedef struct _GStaticPrivateNode GStaticPrivateNode;
927 struct _GStaticPrivateNode
930 GDestroyNotify destroy;
936 * A #GStaticPrivate works almost like a #GPrivate, but it has one
937 * significant advantage. It doesn't need to be created at run-time
938 * like a #GPrivate, but can be defined at compile-time. This is
939 * similar to the difference between #GMutex and #GStaticMutex. Now
940 * look at our <function>give_me_next_number()</function> example with
944 * <title>Using GStaticPrivate for per-thread data</title>
947 * give_me_next_number (<!-- -->)
949 * static GStaticPrivate current_number_key = G_STATIC_PRIVATE_INIT;
950 * int *current_number = g_static_private_get (&current_number_key);
952 * if (!current_number)
954 * current_number = g_new (int,1);
955 * *current_number = 0;
956 * g_static_private_set (&current_number_key, current_number, g_free);
959 * *current_number = calc_next_number (*current_number);
961 * return *current_number;
968 * G_STATIC_PRIVATE_INIT:
970 * Every #GStaticPrivate must be initialized with this macro, before it
974 * GStaticPrivate my_private = G_STATIC_PRIVATE_INIT;
979 * g_static_private_init:
980 * @private_key: a #GStaticPrivate to be initialized
982 * Initializes @private_key. Alternatively you can initialize it with
983 * #G_STATIC_PRIVATE_INIT.
986 g_static_private_init (GStaticPrivate *private_key)
988 private_key->index = 0;
992 * g_static_private_get:
993 * @private_key: a #GStaticPrivate
995 * Works like g_private_get() only for a #GStaticPrivate.
997 * This function works even if g_thread_init() has not yet been called.
999 * Returns: the corresponding pointer
1002 g_static_private_get (GStaticPrivate *private_key)
1004 GRealThread *self = (GRealThread*) g_thread_self ();
1006 gpointer ret = NULL;
1008 LOCK_PRIVATE_DATA (self);
1010 array = self->private_data;
1012 if (array && private_key->index != 0 && private_key->index <= array->len)
1013 ret = g_array_index (array, GStaticPrivateNode,
1014 private_key->index - 1).data;
1016 UNLOCK_PRIVATE_DATA (self);
1021 * g_static_private_set:
1022 * @private_key: a #GStaticPrivate
1023 * @data: the new pointer
1024 * @notify: a function to be called with the pointer whenever the
1025 * current thread ends or sets this pointer again
1027 * Sets the pointer keyed to @private_key for the current thread and
1028 * the function @notify to be called with that pointer (%NULL or
1029 * non-%NULL), whenever the pointer is set again or whenever the
1030 * current thread ends.
1032 * This function works even if g_thread_init() has not yet been called.
1033 * If g_thread_init() is called later, the @data keyed to @private_key
1034 * will be inherited only by the main thread, i.e. the one that called
1037 * <note><para>@notify is used quite differently from @destructor in
1038 * g_private_new().</para></note>
1041 g_static_private_set (GStaticPrivate *private_key,
1043 GDestroyNotify notify)
1045 GRealThread *self = (GRealThread*) g_thread_self ();
1047 static guint next_index = 0;
1048 GStaticPrivateNode *node;
1049 gpointer ddata = NULL;
1050 GDestroyNotify ddestroy = NULL;
1052 if (!private_key->index)
1056 if (!private_key->index)
1058 if (g_thread_free_indices)
1060 private_key->index =
1061 GPOINTER_TO_UINT (g_thread_free_indices->data);
1062 g_thread_free_indices =
1063 g_slist_delete_link (g_thread_free_indices,
1064 g_thread_free_indices);
1067 private_key->index = ++next_index;
1070 G_UNLOCK (g_thread);
1073 LOCK_PRIVATE_DATA (self);
1075 array = self->private_data;
1078 array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
1079 self->private_data = array;
1082 if (private_key->index > array->len)
1083 g_array_set_size (array, private_key->index);
1085 node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
1088 ddestroy = node->destroy;
1091 node->destroy = notify;
1093 UNLOCK_PRIVATE_DATA (self);
1100 * g_static_private_free:
1101 * @private_key: a #GStaticPrivate to be freed
1103 * Releases all resources allocated to @private_key.
1105 * You don't have to call this functions for a #GStaticPrivate with an
1106 * unbounded lifetime, i.e. objects declared 'static', but if you have
1107 * a #GStaticPrivate as a member of a structure and the structure is
1108 * freed, you should also free the #GStaticPrivate.
1111 g_static_private_free (GStaticPrivate *private_key)
1113 guint idx = private_key->index;
1114 GRealThread *thread, *next;
1115 GArray *garbage = NULL;
1120 private_key->index = 0;
1124 thread = g_thread_all_threads;
1126 for (thread = g_thread_all_threads; thread; thread = next)
1130 next = thread->next;
1132 LOCK_PRIVATE_DATA (thread);
1134 array = thread->private_data;
1136 if (array && idx <= array->len)
1138 GStaticPrivateNode *node = &g_array_index (array,
1141 gpointer ddata = node->data;
1142 GDestroyNotify ddestroy = node->destroy;
1145 node->destroy = NULL;
1149 /* defer non-trivial destruction til after we've finished
1150 * iterating, since we must continue to hold the lock */
1151 if (garbage == NULL)
1152 garbage = g_array_new (FALSE, TRUE,
1153 sizeof (GStaticPrivateNode));
1155 g_array_set_size (garbage, garbage->len + 1);
1157 node = &g_array_index (garbage, GStaticPrivateNode,
1160 node->destroy = ddestroy;
1164 UNLOCK_PRIVATE_DATA (thread);
1166 g_thread_free_indices = g_slist_prepend (g_thread_free_indices,
1167 GUINT_TO_POINTER (idx));
1168 G_UNLOCK (g_thread);
1174 for (i = 0; i < garbage->len; i++)
1176 GStaticPrivateNode *node;
1178 node = &g_array_index (garbage, GStaticPrivateNode, i);
1179 node->destroy (node->data);
1182 g_array_free (garbage, TRUE);
1186 /* GThread {{{1 -------------------------------------------------------- */
1189 g_thread_cleanup (gpointer data)
1193 GRealThread* thread = data;
1196 LOCK_PRIVATE_DATA (thread);
1197 array = thread->private_data;
1198 thread->private_data = NULL;
1199 UNLOCK_PRIVATE_DATA (thread);
1205 for (i = 0; i < array->len; i++ )
1207 GStaticPrivateNode *node =
1208 &g_array_index (array, GStaticPrivateNode, i);
1210 node->destroy (node->data);
1212 g_array_free (array, TRUE);
1215 /* We only free the thread structure if it isn't joinable.
1216 * If it is, the structure is freed in g_thread_join()
1218 if (!thread->thread.joinable)
1223 for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
1230 g_thread_all_threads = t->next;
1234 G_UNLOCK (g_thread);
1236 /* Just to make sure, this isn't used any more */
1237 g_system_thread_assign (thread->system_thread, zero_thread);
1244 g_thread_create_proxy (gpointer data)
1246 GRealThread* thread = data;
1250 /* This has to happen before G_LOCK, as that might call g_thread_self */
1251 g_private_set (&g_thread_specific_private, data);
1253 /* The lock makes sure that thread->system_thread is written,
1254 * before thread->thread.func is called. See g_thread_create().
1257 G_UNLOCK (g_thread);
1259 thread->retval = thread->thread.func (thread->thread.data);
1266 * @func: a function to execute in the new thread
1267 * @data: an argument to supply to the new thread
1268 * @joinable: should this thread be joinable?
1269 * @error: return location for error, or %NULL
1271 * This function creates a new thread.
1273 * If @joinable is %TRUE, you can wait for this threads termination
1274 * calling g_thread_join(). Otherwise the thread will just disappear
1275 * when it terminates.
1277 * The new thread executes the function @func with the argument @data.
1278 * If the thread was created successfully, it is returned.
1280 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
1281 * The error is set, if and only if the function returns %NULL.
1283 * Returns: the new #GThread on success
1286 g_thread_create (GThreadFunc func,
1291 return g_thread_create_with_stack_size (func, data, joinable, 0, error);
1295 * g_thread_create_with_stack_size:
1296 * @func: a function to execute in the new thread
1297 * @data: an argument to supply to the new thread
1298 * @joinable: should this thread be joinable?
1299 * @stack_size: a stack size for the new thread
1300 * @error: return location for error
1302 * This function creates a new thread. If the underlying thread
1303 * implementation supports it, the thread gets a stack size of
1304 * @stack_size or the default value for the current platform, if
1307 * If @joinable is %TRUE, you can wait for this threads termination
1308 * calling g_thread_join(). Otherwise the thread will just disappear
1309 * when it terminates.
1311 * The new thread executes the function @func with the argument @data.
1312 * If the thread was created successfully, it is returned.
1314 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
1315 * The error is set, if and only if the function returns %NULL.
1317 * <note><para>Only use g_thread_create_with_stack_size() if you
1318 * really can't use g_thread_create() instead. g_thread_create()
1319 * does not take @stack_size, as it should only be used in cases
1320 * in which it is unavoidable.</para></note>
1322 * Returns: the new #GThread on success
1327 g_thread_create_with_stack_size (GThreadFunc func,
1333 GRealThread* result;
1334 GError *local_error = NULL;
1335 g_return_val_if_fail (func, NULL);
1337 result = g_new0 (GRealThread, 1);
1339 result->thread.joinable = joinable;
1340 result->thread.func = func;
1341 result->thread.data = data;
1342 result->private_data = NULL;
1344 g_system_thread_create (g_thread_create_proxy, result,
1345 stack_size, joinable,
1346 &result->system_thread, &local_error);
1349 result->next = g_thread_all_threads;
1350 g_thread_all_threads = result;
1352 G_UNLOCK (g_thread);
1356 g_propagate_error (error, local_error);
1361 return (GThread*) result;
1366 * @retval: the return value of this thread
1368 * Exits the current thread. If another thread is waiting for that
1369 * thread using g_thread_join() and the current thread is joinable, the
1370 * waiting thread will be woken up and get @retval as the return value
1371 * of g_thread_join(). If the current thread is not joinable, @retval
1372 * is ignored. Calling
1375 * g_thread_exit (retval);
1378 * is equivalent to returning @retval from the function @func, as given
1379 * to g_thread_create().
1381 * <note><para>Never call g_thread_exit() from within a thread of a
1382 * #GThreadPool, as that will mess up the bookkeeping and lead to funny
1383 * and unwanted results.</para></note>
1386 g_thread_exit (gpointer retval)
1388 GRealThread* real = (GRealThread*) g_thread_self ();
1389 real->retval = retval;
1391 g_system_thread_exit ();
1396 * @thread: a #GThread to be waited for
1398 * Waits until @thread finishes, i.e. the function @func, as given to
1399 * g_thread_create(), returns or g_thread_exit() is called by @thread.
1400 * All resources of @thread including the #GThread struct are released.
1401 * @thread must have been created with @joinable=%TRUE in
1402 * g_thread_create(). The value returned by @func or given to
1403 * g_thread_exit() by @thread is returned by this function.
1405 * Returns: the return value of the thread
1408 g_thread_join (GThread* thread)
1410 GRealThread* real = (GRealThread*) thread;
1414 g_return_val_if_fail (thread, NULL);
1415 g_return_val_if_fail (thread->joinable, NULL);
1416 g_return_val_if_fail (!g_system_thread_equal (&real->system_thread, &zero_thread), NULL);
1418 g_system_thread_join (&real->system_thread);
1420 retval = real->retval;
1423 for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
1425 if (t == (GRealThread*) thread)
1430 g_thread_all_threads = t->next;
1434 G_UNLOCK (g_thread);
1436 /* Just to make sure, this isn't used any more */
1437 thread->joinable = 0;
1438 g_system_thread_assign (real->system_thread, zero_thread);
1440 /* the thread structure for non-joinable threads is freed upon
1441 * thread end. We free the memory here. This will leave a loose end,
1442 * if a joinable thread is not joined.
1452 * This functions returns the #GThread corresponding to the calling
1455 * Returns: the current thread
1458 g_thread_self (void)
1460 GRealThread* thread = g_private_get (&g_thread_specific_private);
1464 /* If no thread data is available, provide and set one.
1465 * This can happen for the main thread and for threads
1466 * that are not created by GLib.
1468 thread = g_new0 (GRealThread, 1);
1469 thread->thread.joinable = FALSE; /* This is a safe guess */
1470 thread->thread.func = NULL;
1471 thread->thread.data = NULL;
1472 thread->private_data = NULL;
1474 g_system_thread_self (&thread->system_thread);
1476 g_private_set (&g_thread_specific_private, thread);
1479 thread->next = g_thread_all_threads;
1480 g_thread_all_threads = thread;
1481 G_UNLOCK (g_thread);
1484 return (GThread*)thread;
1489 * @thread_func: function to call for all #GThread structures
1490 * @user_data: second argument to @thread_func
1492 * Call @thread_func on all existing #GThread structures.
1493 * Note that threads may decide to exit while @thread_func is
1494 * running, so without intimate knowledge about the lifetime of
1495 * foreign threads, @thread_func shouldn't access the GThread*
1496 * pointer passed in as first argument. However, @thread_func will
1497 * not be called for threads which are known to have exited already.
1499 * Due to thread lifetime checks, this function has an execution complexity
1500 * which is quadratic in the number of existing threads.
1505 g_thread_foreach (GFunc thread_func,
1508 GSList *slist = NULL;
1509 GRealThread *thread;
1510 g_return_if_fail (thread_func != NULL);
1511 /* snapshot the list of threads for iteration */
1513 for (thread = g_thread_all_threads; thread; thread = thread->next)
1514 slist = g_slist_prepend (slist, thread);
1515 G_UNLOCK (g_thread);
1516 /* walk the list, skipping non-existent threads */
1519 GSList *node = slist;
1521 /* check whether the current thread still exists */
1523 for (thread = g_thread_all_threads; thread; thread = thread->next)
1524 if (thread == node->data)
1526 G_UNLOCK (g_thread);
1528 thread_func (thread, user_data);
1529 g_slist_free_1 (node);
1533 /* GMutex {{{1 ------------------------------------------------------ */
1538 * Allocated and initializes a new #GMutex.
1540 * Returns: a newly allocated #GMutex. Use g_mutex_free() to free
1547 mutex = g_slice_new (GMutex);
1548 g_mutex_init (mutex);
1557 * Destroys a @mutex that has been created with g_mutex_new().
1559 * Calling g_mutex_free() on a locked mutex may result
1560 * in undefined behaviour.
1563 g_mutex_free (GMutex *mutex)
1565 g_mutex_clear (mutex);
1566 g_slice_free (GMutex, mutex);
1569 /* GCond {{{1 ------------------------------------------------------ */
1574 * Allocates and initializes a new #GCond.
1576 * Returns: a newly allocated #GCond. Free with g_cond_free()
1583 cond = g_slice_new (GCond);
1593 * Destroys a #GCond that has been created with g_cond_new().
1596 g_cond_free (GCond *cond)
1598 g_cond_clear (cond);
1599 g_slice_free (GCond, cond);
1602 /* GPrivate {{{1 ------------------------------------------------------ */
1606 * @destructor: a function to destroy the data keyed to
1607 * the #GPrivate when a thread ends
1609 * Creates a new #GPrivate. If @destructor is non-%NULL, it is a
1610 * pointer to a destructor function. Whenever a thread ends and the
1611 * corresponding pointer keyed to this instance of #GPrivate is
1612 * non-%NULL, the destructor is called with this pointer as the
1616 * #GStaticPrivate is a better choice for most uses.
1619 * <note><para>@destructor is used quite differently from @notify in
1620 * g_static_private_set().</para></note>
1622 * <note><para>A #GPrivate cannot be freed. Reuse it instead, if you
1623 * can, to avoid shortage, or use #GStaticPrivate.</para></note>
1625 * <note><para>This function will abort if g_thread_init() has not been
1626 * called yet.</para></note>
1628 * Returns: a newly allocated #GPrivate
1631 g_private_new (GDestroyNotify notify)
1635 key = g_slice_new (GPrivate);
1636 g_private_init (key, notify);
1641 /* vim: set foldmethod=marker: */