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__
43 #include "deprecated/gthread.h"
44 #include "gthreadprivate.h"
57 #endif /* G_OS_WIN32 */
64 #include "gtestutils.h"
70 * @short_description: thread abstraction; including threads, different
71 * mutexes, conditions and thread private data
72 * @see_also: #GThreadPool, #GAsyncQueue
74 * Threads act almost like processes, but unlike processes all threads
75 * of one process share the same memory. This is good, as it provides
76 * easy communication between the involved threads via this shared
77 * memory, and it is bad, because strange things (so called
78 * "Heisenbugs") might happen if the program is not carefully designed.
79 * In particular, due to the concurrent nature of threads, no
80 * assumptions on the order of execution of code running in different
81 * threads can be made, unless order is explicitly forced by the
82 * programmer through synchronization primitives.
84 * The aim of the thread related functions in GLib is to provide a
85 * portable means for writing multi-threaded software. There are
86 * primitives for mutexes to protect the access to portions of memory
87 * (#GMutex, #GRecMutex and #GRWLock). There is a facility to use
88 * individual bits for locks (g_bit_lock()). There are primitives
89 * for condition variables to allow synchronization of threads (#GCond).
90 * There are primitives for thread-private data - data that every thread
91 * has a private instance of (#GPrivate, #GStaticPrivate). There are
92 * facilities for one-time initialization (#GOnce, g_once_init_enter()).
93 * Last but definitely not least there are primitives to portably create
94 * and manage threads (#GThread).
96 * The threading system is initialized with g_thread_init(), which
97 * takes an optional custom thread implementation or %NULL for the
98 * default implementation. If you want to call g_thread_init() with a
99 * non-%NULL argument this must be done before executing any other GLib
100 * functions (except g_mem_set_vtable()). This is a requirement even if
101 * no threads are in fact ever created by the process.
103 * Calling g_thread_init() with a %NULL argument is somewhat more
104 * relaxed. You may call any other glib functions in the main thread
105 * before g_thread_init() as long as g_thread_init() is not called from
106 * a glib callback, or with any locks held. However, many libraries
107 * above glib does not support late initialization of threads, so doing
108 * this should be avoided if possible.
110 * Please note that since version 2.24 the GObject initialization
111 * function g_type_init() initializes threads (with a %NULL argument),
112 * so most applications, including those using Gtk+ will run with
113 * threads enabled. If you want a special thread implementation, make
114 * sure you call g_thread_init() before g_type_init() is called.
116 * After calling g_thread_init(), GLib is completely thread safe (all
117 * global data is automatically locked), but individual data structure
118 * instances are not automatically locked for performance reasons. So,
119 * for example you must coordinate accesses to the same #GHashTable
120 * from multiple threads. The two notable exceptions from this rule
121 * are #GMainLoop and #GAsyncQueue, which <emphasis>are</emphasis>
122 * threadsafe and need no further application-level locking to be
123 * accessed from multiple threads.
127 * G_THREADS_IMPL_POSIX:
129 * This macro is defined if POSIX style threads are used.
135 * This macro is defined, for backward compatibility, to indicate that
136 * GLib has been compiled with thread support. As of glib 2.28, it is
141 * G_THREADS_IMPL_NONE:
143 * This macro is defined if no thread implementation is used. You can,
144 * however, provide one to g_thread_init() to make GLib multi-thread
148 /* G_LOCK Documentation {{{1 ---------------------------------------------- */
150 /* IMPLEMENTATION NOTE:
152 * G_LOCK_DEFINE and friends are convenience macros defined in
153 * gthread.h. Their documentation lives here.
158 * @name: the name of the lock.
160 * The %G_LOCK_* macros provide a convenient interface to #GStaticMutex
161 * with the advantage that they will expand to nothing in programs
162 * compiled against a thread-disabled GLib, saving code and memory
163 * there. #G_LOCK_DEFINE defines a lock. It can appear anywhere
164 * variable definitions may appear in programs, i.e. in the first block
165 * of a function or outside of functions. The @name parameter will be
166 * mangled to get the name of the #GStaticMutex. This means that you
167 * can use names of existing variables as the parameter - e.g. the name
168 * of the variable you intent to protect with the lock. Look at our
169 * <function>give_me_next_number()</function> example using the
173 * <title>Using the %G_LOCK_* convenience macros</title>
175 * G_LOCK_DEFINE (current_number);
178 * give_me_next_number (void)
180 * static int current_number = 0;
183 * G_LOCK (current_number);
184 * ret_val = current_number = calc_next_number (current_number);
185 * G_UNLOCK (current_number);
194 * G_LOCK_DEFINE_STATIC:
195 * @name: the name of the lock.
197 * This works like #G_LOCK_DEFINE, but it creates a static object.
202 * @name: the name of the lock.
204 * This declares a lock, that is defined with #G_LOCK_DEFINE in another
210 * @name: the name of the lock.
212 * Works like g_mutex_lock(), but for a lock defined with
218 * @name: the name of the lock.
219 * @Returns: %TRUE, if the lock could be locked.
221 * Works like g_mutex_trylock(), but for a lock defined with
227 * @name: the name of the lock.
229 * Works like g_mutex_unlock(), but for a lock defined with
233 /* GThreadError {{{1 ------------------------------------------------------- */
236 * @G_THREAD_ERROR_AGAIN: a thread couldn't be created due to resource
237 * shortage. Try again later.
239 * Possible errors of thread related functions.
245 * The error domain of the GLib thread subsystem.
248 g_thread_error_quark (void)
250 return g_quark_from_static_string ("g_thread_error");
253 /* Miscellaneous Structures {{{1 ------------------------------------------ */
254 typedef struct _GRealThread GRealThread;
258 /* Bit 0 protects private_data. To avoid deadlocks, do not block while
259 * holding this (particularly on the g_thread lock). */
260 volatile gint private_data_lock;
261 GArray *private_data;
264 GSystemThread system_thread;
267 #define LOCK_PRIVATE_DATA(self) g_bit_lock (&(self)->private_data_lock, 0)
268 #define UNLOCK_PRIVATE_DATA(self) g_bit_unlock (&(self)->private_data_lock, 0)
270 typedef struct _GStaticPrivateNode GStaticPrivateNode;
271 struct _GStaticPrivateNode
274 GDestroyNotify destroy;
277 static void g_thread_cleanup (gpointer data);
278 static guint64 gettime (void);
280 guint64 (*g_thread_gettime) (void) = gettime;
282 /* Global Variables {{{1 -------------------------------------------------- */
284 static GSystemThread zero_thread; /* This is initialized to all zero */
285 gboolean g_thread_use_default_impl = TRUE;
288 * g_thread_supported:
289 * @Returns: %TRUE, if the thread system is initialized.
291 * This function returns %TRUE if the thread system is initialized, and
292 * %FALSE if it is not.
294 * <note><para>This function is actually a macro. Apart from taking the
295 * address of it you can however use it as if it was a
296 * function.</para></note>
299 /* IMPLEMENTATION NOTE:
301 * g_thread_supported() is just returns g_threads_got_initialized
303 gboolean g_threads_got_initialized = FALSE;
306 /* Thread Implementation Virtual Function Table {{{1 ---------------------- */
307 /* Virtual Function Table Documentation {{{2 ------------------------------ */
310 * @mutex_new: virtual function pointer for g_mutex_new()
311 * @mutex_lock: virtual function pointer for g_mutex_lock()
312 * @mutex_trylock: virtual function pointer for g_mutex_trylock()
313 * @mutex_unlock: virtual function pointer for g_mutex_unlock()
314 * @mutex_free: virtual function pointer for g_mutex_free()
315 * @cond_new: virtual function pointer for g_cond_new()
316 * @cond_signal: virtual function pointer for g_cond_signal()
317 * @cond_broadcast: virtual function pointer for g_cond_broadcast()
318 * @cond_wait: virtual function pointer for g_cond_wait()
319 * @cond_timed_wait: virtual function pointer for g_cond_timed_wait()
320 * @cond_free: virtual function pointer for g_cond_free()
321 * @private_new: virtual function pointer for g_private_new()
322 * @private_get: virtual function pointer for g_private_get()
323 * @private_set: virtual function pointer for g_private_set()
324 * @thread_create: virtual function pointer for g_thread_create()
325 * @thread_yield: virtual function pointer for g_thread_yield()
326 * @thread_join: virtual function pointer for g_thread_join()
327 * @thread_exit: virtual function pointer for g_thread_exit()
328 * @thread_set_priority: virtual function pointer for
329 * g_thread_set_priority()
330 * @thread_self: virtual function pointer for g_thread_self()
331 * @thread_equal: used internally by recursive mutex locks and by some
334 * This function table is used by g_thread_init() to initialize the
335 * thread system. The functions in the table are directly used by their
336 * g_* prepended counterparts (described in this document). For
337 * example, if you call g_mutex_new() then mutex_new() from the table
338 * provided to g_thread_init() will be called.
340 * <note><para>Do not use this struct unless you know what you are
341 * doing.</para></note>
344 /* GMutex Virtual Functions {{{2 ------------------------------------------ */
349 * The #GMutex struct is an opaque data structure to represent a mutex
350 * (mutual exclusion). It can be used to protect data against shared
351 * access. Take for example the following function:
354 * <title>A function which will not work in a threaded environment</title>
357 * give_me_next_number (void)
359 * static int current_number = 0;
361 * /<!-- -->* now do a very complicated calculation to calculate the new
362 * * number, this might for example be a random number generator
364 * current_number = calc_next_number (current_number);
366 * return current_number;
371 * It is easy to see that this won't work in a multi-threaded
372 * application. There current_number must be protected against shared
373 * access. A first naive implementation would be:
376 * <title>The wrong way to write a thread-safe function</title>
379 * give_me_next_number (void)
381 * static int current_number = 0;
383 * static GMutex * mutex = NULL;
385 * if (!mutex) mutex = g_mutex_new (<!-- -->);
387 * g_mutex_lock (mutex);
388 * ret_val = current_number = calc_next_number (current_number);
389 * g_mutex_unlock (mutex);
396 * This looks like it would work, but there is a race condition while
397 * constructing the mutex and this code cannot work reliable. Please do
398 * not use such constructs in your own programs! One working solution
402 * <title>A correct thread-safe function</title>
404 * static GMutex *give_me_next_number_mutex = NULL;
406 * /<!-- -->* this function must be called before any call to
407 * * give_me_next_number(<!-- -->)
409 * * it must be called exactly once.
412 * init_give_me_next_number (void)
414 * g_assert (give_me_next_number_mutex == NULL);
415 * give_me_next_number_mutex = g_mutex_new (<!-- -->);
419 * give_me_next_number (void)
421 * static int current_number = 0;
424 * g_mutex_lock (give_me_next_number_mutex);
425 * ret_val = current_number = calc_next_number (current_number);
426 * g_mutex_unlock (give_me_next_number_mutex);
433 * A statically initialized #GMutex provides an even simpler and safer
437 * <title>Using a statically allocated mutex</title>
440 * give_me_next_number (void)
442 * static GMutex mutex = G_MUTEX_INITIALIZER;
443 * static int current_number = 0;
446 * g_mutex_lock (&mutex);
447 * ret_val = current_number = calc_next_number (current_number);
448 * g_mutex_unlock (&mutex);
455 * A #GMutex should only be accessed via the following functions.
458 /* GCond Virtual Functions {{{2 ------------------------------------------ */
463 * The #GCond struct is an opaque data structure that represents a
464 * condition. Threads can block on a #GCond if they find a certain
465 * condition to be false. If other threads change the state of this
466 * condition they signal the #GCond, and that causes the waiting
467 * threads to be woken up.
471 * Using GCond to block a thread until a condition is satisfied
474 * GCond* data_cond = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
475 * GMutex* data_mutex = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
476 * gpointer current_data = NULL;
479 * push_data (gpointer data)
481 * g_mutex_lock (data_mutex);
482 * current_data = data;
483 * g_cond_signal (data_cond);
484 * g_mutex_unlock (data_mutex);
492 * g_mutex_lock (data_mutex);
493 * while (!current_data)
494 * g_cond_wait (data_cond, data_mutex);
495 * data = current_data;
496 * current_data = NULL;
497 * g_mutex_unlock (data_mutex);
504 * Whenever a thread calls pop_data() now, it will wait until
505 * current_data is non-%NULL, i.e. until some other thread
506 * has called push_data().
508 * <note><para>It is important to use the g_cond_wait() and
509 * g_cond_timed_wait() functions only inside a loop which checks for the
510 * condition to be true. It is not guaranteed that the waiting thread
511 * will find the condition fulfilled after it wakes up, even if the
512 * signaling thread left the condition in that state: another thread may
513 * have altered the condition before the waiting thread got the chance
514 * to be woken up, even if the condition itself is protected by a
515 * #GMutex, like above.</para></note>
517 * A #GCond should only be accessed via the following functions.
520 /* GPrivate Virtual Functions {{{2 --------------------------------------- */
526 * #GStaticPrivate is a better choice for most uses.
529 * The #GPrivate struct is an opaque data structure to represent a
530 * thread private data key. Threads can thereby obtain and set a
531 * pointer which is private to the current thread. Take our
532 * <function>give_me_next_number(<!-- -->)</function> example from
533 * above. Suppose we don't want <literal>current_number</literal> to be
534 * shared between the threads, but instead to be private to each thread.
535 * This can be done as follows:
538 * <title>Using GPrivate for per-thread data</title>
540 * GPrivate* current_number_key = NULL; /<!-- -->* Must be initialized somewhere
541 * with g_private_new (g_free); *<!-- -->/
544 * give_me_next_number (void)
546 * int *current_number = g_private_get (current_number_key);
548 * if (!current_number)
550 * current_number = g_new (int, 1);
551 * *current_number = 0;
552 * g_private_set (current_number_key, current_number);
555 * *current_number = calc_next_number (*current_number);
557 * return *current_number;
562 * Here the pointer belonging to the key
563 * <literal>current_number_key</literal> is read. If it is %NULL, it has
564 * not been set yet. Then get memory for an integer value, assign this
565 * memory to the pointer and write the pointer back. Now we have an
566 * integer value that is private to the current thread.
568 * The #GPrivate struct should only be accessed via the following
571 * <note><para>All of the <function>g_private_*</function> functions are
572 * actually macros. Apart from taking their addresses, you can however
573 * use them as if they were functions.</para></note>
576 /* GThread Virtual Functions {{{2 ---------------------------------------- */
580 * The #GThread struct represents a running thread. It has three public
581 * read-only members, but the underlying struct is bigger, so you must
582 * not copy this struct.
584 * <note><para>Resources for a joinable thread are not fully released
585 * until g_thread_join() is called for that thread.</para></note>
590 * @data: data passed to the thread.
591 * @Returns: the return value of the thread, which will be returned by
594 * Specifies the type of the @func functions passed to
595 * g_thread_create() or g_thread_create_full().
600 * @G_THREAD_PRIORITY_LOW: a priority lower than normal
601 * @G_THREAD_PRIORITY_NORMAL: the default priority
602 * @G_THREAD_PRIORITY_HIGH: a priority higher than normal
603 * @G_THREAD_PRIORITY_URGENT: the highest priority
605 * Deprecated:2.32: thread priorities no longer have any effect.
608 /* Local Data {{{1 -------------------------------------------------------- */
610 static GMutex g_once_mutex = G_MUTEX_INIT;
611 static GCond g_once_cond = G_COND_INIT;
612 static GPrivate g_thread_specific_private;
613 static GRealThread *g_thread_all_threads = NULL;
614 static GSList *g_thread_free_indices = NULL;
615 static GSList* g_once_init_list = NULL;
617 G_LOCK_DEFINE_STATIC (g_thread);
619 /* Initialisation {{{1 ---------------------------------------------------- */
623 * @vtable: a function table of type #GThreadFunctions, that provides
624 * the entry points to the thread system to be used.
626 * If you use GLib from more than one thread, you must initialize the
627 * thread system by calling g_thread_init(). Most of the time you will
628 * only have to call <literal>g_thread_init (NULL)</literal>.
630 * <note><para>Do not call g_thread_init() with a non-%NULL parameter unless
631 * you really know what you are doing.</para></note>
633 * <note><para>g_thread_init() must not be called directly or indirectly as a
634 * callback from GLib. Also no mutexes may be currently locked while
635 * calling g_thread_init().</para></note>
637 * <note><para>g_thread_init() changes the way in which #GTimer measures
638 * elapsed time. As a consequence, timers that are running while
639 * g_thread_init() is called may report unreliable times.</para></note>
641 * Calling g_thread_init() multiple times is allowed (since version
642 * 2.24), but nothing happens except for the first call. If the
643 * argument is non-%NULL on such a call a warning will be printed, but
644 * otherwise the argument is ignored.
646 * If no thread system is available and @vtable is %NULL or if not all
647 * elements of @vtable are non-%NULL, then g_thread_init() will abort.
649 * <note><para>To use g_thread_init() in your program, you have to link with
650 * the libraries that the command <command>pkg-config --libs
651 * gthread-2.0</command> outputs. This is not the case for all the
652 * other thread related functions of GLib. Those can be used without
653 * having to link with the thread libraries.</para></note>
656 /* This must be called only once, before any threads are created.
657 * It will only be called from g_thread_init() in -lgthread.
660 g_thread_init_glib (void)
662 static gboolean already_done;
669 /* We let the main thread (the one that calls g_thread_init) inherit
670 * the static_private data set before calling g_thread_init
672 GRealThread* main_thread = (GRealThread*) g_thread_self ();
674 /* setup the basic threading system */
675 g_threads_got_initialized = TRUE;
676 g_private_init (&g_thread_specific_private, g_thread_cleanup);
677 g_private_set (&g_thread_specific_private, main_thread);
678 g_system_thread_self (&main_thread->system_thread);
680 /* accomplish log system initialization to enable messaging */
681 _g_messages_thread_init_nomessage ();
684 /* The following sections implement: GOnce, GStaticMutex, GStaticRecMutex,
688 /* GOnce {{{1 ------------------------------------------------------------- */
692 * @status: the status of the #GOnce
693 * @retval: the value returned by the call to the function, if @status
694 * is %G_ONCE_STATUS_READY
696 * A #GOnce struct controls a one-time initialization function. Any
697 * one-time initialization function must have its own unique #GOnce
706 * A #GOnce must be initialized with this macro before it can be used.
710 * GOnce my_once = G_ONCE_INIT;
719 * @G_ONCE_STATUS_NOTCALLED: the function has not been called yet.
720 * @G_ONCE_STATUS_PROGRESS: the function call is currently in progress.
721 * @G_ONCE_STATUS_READY: the function has been called.
723 * The possible statuses of a one-time initialization function
724 * controlled by a #GOnce struct.
731 * @once: a #GOnce structure
732 * @func: the #GThreadFunc function associated to @once. This function
733 * is called only once, regardless of the number of times it and
734 * its associated #GOnce struct are passed to g_once().
735 * @arg: data to be passed to @func
737 * The first call to this routine by a process with a given #GOnce
738 * struct calls @func with the given argument. Thereafter, subsequent
739 * calls to g_once() with the same #GOnce struct do not call @func
740 * again, but return the stored result of the first call. On return
741 * from g_once(), the status of @once will be %G_ONCE_STATUS_READY.
743 * For example, a mutex or a thread-specific data key must be created
744 * exactly once. In a threaded environment, calling g_once() ensures
745 * that the initialization is serialized across multiple threads.
747 * <note><para>Calling g_once() recursively on the same #GOnce struct in
748 * @func will lead to a deadlock.</para></note>
753 * get_debug_flags (void)
755 * static GOnce my_once = G_ONCE_INIT;
757 * g_once (&my_once, parse_debug_flags, NULL);
759 * return my_once.retval;
767 g_once_impl (GOnce *once,
771 g_mutex_lock (&g_once_mutex);
773 while (once->status == G_ONCE_STATUS_PROGRESS)
774 g_cond_wait (&g_once_cond, &g_once_mutex);
776 if (once->status != G_ONCE_STATUS_READY)
778 once->status = G_ONCE_STATUS_PROGRESS;
779 g_mutex_unlock (&g_once_mutex);
781 once->retval = func (arg);
783 g_mutex_lock (&g_once_mutex);
784 once->status = G_ONCE_STATUS_READY;
785 g_cond_broadcast (&g_once_cond);
788 g_mutex_unlock (&g_once_mutex);
795 * @value_location: location of a static initializable variable
797 * @Returns: %TRUE if the initialization section should be entered,
798 * %FALSE and blocks otherwise
800 * Function to be called when starting a critical initialization
801 * section. The argument @value_location must point to a static
802 * 0-initialized variable that will be set to a value other than 0 at
803 * the end of the initialization section. In combination with
804 * g_once_init_leave() and the unique address @value_location, it can
805 * be ensured that an initialization section will be executed only once
806 * during a program's life time, and that concurrent threads are
807 * blocked until initialization completed. To be used in constructs
812 * static gsize initialization_value = 0;
814 * if (g_once_init_enter (&initialization_value))
816 * gsize setup_value = 42; /<!-- -->* initialization code here *<!-- -->/
818 * g_once_init_leave (&initialization_value, setup_value);
821 * /<!-- -->* use initialization_value here *<!-- -->/
828 g_once_init_enter_impl (volatile gsize *value_location)
830 gboolean need_init = FALSE;
831 g_mutex_lock (&g_once_mutex);
832 if (g_atomic_pointer_get (value_location) == NULL)
834 if (!g_slist_find (g_once_init_list, (void*) value_location))
837 g_once_init_list = g_slist_prepend (g_once_init_list, (void*) value_location);
841 g_cond_wait (&g_once_cond, &g_once_mutex);
842 while (g_slist_find (g_once_init_list, (void*) value_location));
844 g_mutex_unlock (&g_once_mutex);
850 * @value_location: location of a static initializable variable
852 * @initialization_value: new non-0 value for *@value_location.
854 * Counterpart to g_once_init_enter(). Expects a location of a static
855 * 0-initialized initialization variable, and an initialization value
856 * other than 0. Sets the variable to the initialization value, and
857 * releases concurrent threads blocking in g_once_init_enter() on this
858 * initialization variable.
863 g_once_init_leave (volatile gsize *value_location,
864 gsize initialization_value)
866 g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
867 g_return_if_fail (initialization_value != 0);
868 g_return_if_fail (g_once_init_list != NULL);
870 g_atomic_pointer_set (value_location, initialization_value);
871 g_mutex_lock (&g_once_mutex);
872 g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
873 g_cond_broadcast (&g_once_cond);
874 g_mutex_unlock (&g_once_mutex);
877 /* GStaticMutex {{{1 ------------------------------------------------------ */
882 * A #GStaticMutex works like a #GMutex.
883 * Prior to GLib 2.32, GStaticMutex had the significant advantage
884 * that it doesn't need to be created at run-time, but can be defined
885 * at compile-time. Since 2.32, #GMutex can be statically allocated
886 * as well, and GStaticMutex has been deprecated.
888 * Here is a version of our give_me_next_number() example using
893 * Using <structname>GStaticMutex</structname>
894 * to simplify thread-safe programming
898 * give_me_next_number (void)
900 * static int current_number = 0;
902 * static GStaticMutex mutex = G_STATIC_MUTEX_INIT;
904 * g_static_mutex_lock (&mutex);
905 * ret_val = current_number = calc_next_number (current_number);
906 * g_static_mutex_unlock (&mutex);
913 * Sometimes you would like to dynamically create a mutex. If you don't
914 * want to require prior calling to g_thread_init(), because your code
915 * should also be usable in non-threaded programs, you are not able to
916 * use g_mutex_new() and thus #GMutex, as that requires a prior call to
917 * g_thread_init(). In theses cases you can also use a #GStaticMutex.
918 * It must be initialized with g_static_mutex_init() before using it
919 * and freed with with g_static_mutex_free() when not needed anymore to
920 * free up any allocated resources.
922 * Even though #GStaticMutex is not opaque, it should only be used with
923 * the following functions, as it is defined differently on different
926 * All of the <function>g_static_mutex_*</function> functions apart
927 * from <function>g_static_mutex_get_mutex</function> can also be used
928 * even if g_thread_init() has not yet been called. Then they do
929 * nothing, apart from <function>g_static_mutex_trylock</function>,
930 * which does nothing but returning %TRUE.
932 * <note><para>All of the <function>g_static_mutex_*</function>
933 * functions are actually macros. Apart from taking their addresses, you
934 * can however use them as if they were functions.</para></note>
938 * G_STATIC_MUTEX_INIT:
940 * A #GStaticMutex must be initialized with this macro, before it can
941 * be used. This macro can used be to initialize a variable, but it
942 * cannot be assigned to a variable. In that case you have to use
943 * g_static_mutex_init().
946 * GStaticMutex my_mutex = G_STATIC_MUTEX_INIT;
951 * g_static_mutex_init:
952 * @mutex: a #GStaticMutex to be initialized.
954 * Initializes @mutex.
955 * Alternatively you can initialize it with #G_STATIC_MUTEX_INIT.
957 * Deprecated: 2.32: Use g_mutex_init()
960 g_static_mutex_init (GStaticMutex *mutex)
962 static const GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
964 g_return_if_fail (mutex);
969 /* IMPLEMENTATION NOTE:
971 * On some platforms a GStaticMutex is actually a normal GMutex stored
972 * inside of a structure instead of being allocated dynamically. We can
973 * only do this for platforms on which we know, in advance, how to
974 * allocate (size) and initialise (value) that memory.
976 * On other platforms, a GStaticMutex is nothing more than a pointer to
977 * a GMutex. In that case, the first access we make to the static mutex
978 * must first allocate the normal GMutex and store it into the pointer.
980 * configure.ac writes macros into glibconfig.h to determine if
981 * g_static_mutex_get_mutex() accesses the structure in memory directly
982 * (on platforms where we are able to do that) or if it ends up here,
983 * where we may have to allocate the GMutex before returning it.
987 * g_static_mutex_get_mutex:
988 * @mutex: a #GStaticMutex.
989 * @Returns: the #GMutex corresponding to @mutex.
991 * For some operations (like g_cond_wait()) you must have a #GMutex
992 * instead of a #GStaticMutex. This function will return the
993 * corresponding #GMutex for @mutex.
995 * Deprecated: 2.32: Just use a #GMutex
998 g_static_mutex_get_mutex_impl (GMutex** mutex)
1002 if (!g_thread_supported ())
1005 result = g_atomic_pointer_get (mutex);
1009 g_mutex_lock (&g_once_mutex);
1014 result = g_mutex_new ();
1015 g_atomic_pointer_set (mutex, result);
1018 g_mutex_unlock (&g_once_mutex);
1024 /* IMPLEMENTATION NOTE:
1026 * g_static_mutex_lock(), g_static_mutex_trylock() and
1027 * g_static_mutex_unlock() are all preprocessor macros that wrap the
1028 * corresponding g_mutex_*() function around a call to
1029 * g_static_mutex_get_mutex().
1033 * g_static_mutex_lock:
1034 * @mutex: a #GStaticMutex.
1036 * Works like g_mutex_lock(), but for a #GStaticMutex.
1038 * Deprecated: 2.32: Use g_mutex_lock()
1042 * g_static_mutex_trylock:
1043 * @mutex: a #GStaticMutex.
1044 * @Returns: %TRUE, if the #GStaticMutex could be locked.
1046 * Works like g_mutex_trylock(), but for a #GStaticMutex.
1048 * Deprecated: 2.32: Use g_mutex_trylock()
1052 * g_static_mutex_unlock:
1053 * @mutex: a #GStaticMutex.
1055 * Works like g_mutex_unlock(), but for a #GStaticMutex.
1057 * Deprecated: 2.32: Use g_mutex_unlock()
1061 * g_static_mutex_free:
1062 * @mutex: a #GStaticMutex to be freed.
1064 * Releases all resources allocated to @mutex.
1066 * You don't have to call this functions for a #GStaticMutex with an
1067 * unbounded lifetime, i.e. objects declared 'static', but if you have
1068 * a #GStaticMutex as a member of a structure and the structure is
1069 * freed, you should also free the #GStaticMutex.
1071 * <note><para>Calling g_static_mutex_free() on a locked mutex may
1072 * result in undefined behaviour.</para></note>
1074 * Deprecated: 2.32: Use g_mutex_free()
1077 g_static_mutex_free (GStaticMutex* mutex)
1079 GMutex **runtime_mutex;
1081 g_return_if_fail (mutex);
1083 /* The runtime_mutex is the first (or only) member of GStaticMutex,
1084 * see both versions (of glibconfig.h) in configure.ac. Note, that
1085 * this variable is NULL, if g_thread_init() hasn't been called or
1086 * if we're using the default thread implementation and it provides
1087 * static mutexes. */
1088 runtime_mutex = ((GMutex**)mutex);
1091 g_mutex_free (*runtime_mutex);
1093 *runtime_mutex = NULL;
1096 /* ------------------------------------------------------------------------ */
1101 * A #GStaticRecMutex works like a #GStaticMutex, but it can be locked
1102 * multiple times by one thread. If you enter it n times, you have to
1103 * unlock it n times again to let other threads lock it. An exception
1104 * is the function g_static_rec_mutex_unlock_full(): that allows you to
1105 * unlock a #GStaticRecMutex completely returning the depth, (i.e. the
1106 * number of times this mutex was locked). The depth can later be used
1107 * to restore the state of the #GStaticRecMutex by calling
1108 * g_static_rec_mutex_lock_full(). In GLib 2.32, #GStaticRecMutex has
1109 * been deprecated in favor of #GRecMutex.
1111 * Even though #GStaticRecMutex is not opaque, it should only be used
1112 * with the following functions.
1114 * All of the <function>g_static_rec_mutex_*</function> functions can
1115 * be used even if g_thread_init() has not been called. Then they do
1116 * nothing, apart from <function>g_static_rec_mutex_trylock</function>,
1117 * which does nothing but returning %TRUE.
1121 * G_STATIC_REC_MUTEX_INIT:
1123 * A #GStaticRecMutex must be initialized with this macro before it can
1124 * be used. This macro can used be to initialize a variable, but it
1125 * cannot be assigned to a variable. In that case you have to use
1126 * g_static_rec_mutex_init().
1129 * GStaticRecMutex my_mutex = G_STATIC_REC_MUTEX_INIT;
1134 * g_static_rec_mutex_init:
1135 * @mutex: a #GStaticRecMutex to be initialized.
1137 * A #GStaticRecMutex must be initialized with this function before it
1138 * can be used. Alternatively you can initialize it with
1139 * #G_STATIC_REC_MUTEX_INIT.
1141 * Deprecated: 2.32: Use g_rec_mutex_init()
1144 g_static_rec_mutex_init (GStaticRecMutex *mutex)
1146 static const GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
1148 g_return_if_fail (mutex);
1150 *mutex = init_mutex;
1154 * g_static_rec_mutex_lock:
1155 * @mutex: a #GStaticRecMutex to lock.
1157 * Locks @mutex. If @mutex is already locked by another thread, the
1158 * current thread will block until @mutex is unlocked by the other
1159 * thread. If @mutex is already locked by the calling thread, this
1160 * functions increases the depth of @mutex and returns immediately.
1162 * Deprecated: 2.32: Use g_rec_mutex_lock()
1165 g_static_rec_mutex_lock (GStaticRecMutex* mutex)
1169 g_return_if_fail (mutex);
1171 if (!g_thread_supported ())
1174 g_system_thread_self (&self);
1176 if (g_system_thread_equal (&self, &mutex->owner))
1181 g_static_mutex_lock (&mutex->mutex);
1182 g_system_thread_assign (mutex->owner, self);
1187 * g_static_rec_mutex_trylock:
1188 * @mutex: a #GStaticRecMutex to lock.
1189 * @Returns: %TRUE, if @mutex could be locked.
1191 * Tries to lock @mutex. If @mutex is already locked by another thread,
1192 * it immediately returns %FALSE. Otherwise it locks @mutex and returns
1193 * %TRUE. If @mutex is already locked by the calling thread, this
1194 * functions increases the depth of @mutex and immediately returns
1197 * Deprecated: 2.32: Use g_rec_mutex_trylock()
1200 g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
1204 g_return_val_if_fail (mutex, FALSE);
1206 if (!g_thread_supported ())
1209 g_system_thread_self (&self);
1211 if (g_system_thread_equal (&self, &mutex->owner))
1217 if (!g_static_mutex_trylock (&mutex->mutex))
1220 g_system_thread_assign (mutex->owner, self);
1226 * g_static_rec_mutex_unlock:
1227 * @mutex: a #GStaticRecMutex to unlock.
1229 * Unlocks @mutex. Another thread will be allowed to lock @mutex only
1230 * when it has been unlocked as many times as it had been locked
1231 * before. If @mutex is completely unlocked and another thread is
1232 * blocked in a g_static_rec_mutex_lock() call for @mutex, it will be
1233 * woken and can lock @mutex itself.
1235 * Deprecated: 2.32: Use g_rec_mutex_unlock()
1238 g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
1240 g_return_if_fail (mutex);
1242 if (!g_thread_supported ())
1245 if (mutex->depth > 1)
1250 g_system_thread_assign (mutex->owner, zero_thread);
1251 g_static_mutex_unlock (&mutex->mutex);
1255 * g_static_rec_mutex_lock_full:
1256 * @mutex: a #GStaticRecMutex to lock.
1257 * @depth: number of times this mutex has to be unlocked to be
1258 * completely unlocked.
1260 * Works like calling g_static_rec_mutex_lock() for @mutex @depth times.
1262 * Deprecated: 2.32: Use g_rec_mutex_lock()
1265 g_static_rec_mutex_lock_full (GStaticRecMutex *mutex,
1269 g_return_if_fail (mutex);
1271 if (!g_thread_supported ())
1277 g_system_thread_self (&self);
1279 if (g_system_thread_equal (&self, &mutex->owner))
1281 mutex->depth += depth;
1284 g_static_mutex_lock (&mutex->mutex);
1285 g_system_thread_assign (mutex->owner, self);
1286 mutex->depth = depth;
1290 * g_static_rec_mutex_unlock_full:
1291 * @mutex: a #GStaticRecMutex to completely unlock.
1292 * @Returns: number of times @mutex has been locked by the current
1295 * Completely unlocks @mutex. If another thread is blocked in a
1296 * g_static_rec_mutex_lock() call for @mutex, it will be woken and can
1297 * lock @mutex itself. This function returns the number of times that
1298 * @mutex has been locked by the current thread. To restore the state
1299 * before the call to g_static_rec_mutex_unlock_full() you can call
1300 * g_static_rec_mutex_lock_full() with the depth returned by this
1303 * Deprecated: 2.32: Use g_rec_mutex_unlock()
1306 g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
1310 g_return_val_if_fail (mutex, 0);
1312 if (!g_thread_supported ())
1315 depth = mutex->depth;
1317 g_system_thread_assign (mutex->owner, zero_thread);
1319 g_static_mutex_unlock (&mutex->mutex);
1325 * g_static_rec_mutex_free:
1326 * @mutex: a #GStaticRecMutex to be freed.
1328 * Releases all resources allocated to a #GStaticRecMutex.
1330 * You don't have to call this functions for a #GStaticRecMutex with an
1331 * unbounded lifetime, i.e. objects declared 'static', but if you have
1332 * a #GStaticRecMutex as a member of a structure and the structure is
1333 * freed, you should also free the #GStaticRecMutex.
1335 * Deprecated: 2.32: Use g_rec_mutex_clear()
1338 g_static_rec_mutex_free (GStaticRecMutex *mutex)
1340 g_return_if_fail (mutex);
1342 g_static_mutex_free (&mutex->mutex);
1345 /* GStaticPrivate {{{1 ---------------------------------------------------- */
1350 * A #GStaticPrivate works almost like a #GPrivate, but it has one
1351 * significant advantage. It doesn't need to be created at run-time
1352 * like a #GPrivate, but can be defined at compile-time. This is
1353 * similar to the difference between #GMutex and #GStaticMutex. Now
1354 * look at our <function>give_me_next_number()</function> example with
1358 * <title>Using GStaticPrivate for per-thread data</title>
1361 * give_me_next_number (<!-- -->)
1363 * static GStaticPrivate current_number_key = G_STATIC_PRIVATE_INIT;
1364 * int *current_number = g_static_private_get (&current_number_key);
1366 * if (!current_number)
1368 * current_number = g_new (int,1);
1369 * *current_number = 0;
1370 * g_static_private_set (&current_number_key, current_number, g_free);
1373 * *current_number = calc_next_number (*current_number);
1375 * return *current_number;
1382 * G_STATIC_PRIVATE_INIT:
1384 * Every #GStaticPrivate must be initialized with this macro, before it
1388 * GStaticPrivate my_private = G_STATIC_PRIVATE_INIT;
1393 * g_static_private_init:
1394 * @private_key: a #GStaticPrivate to be initialized.
1396 * Initializes @private_key. Alternatively you can initialize it with
1397 * #G_STATIC_PRIVATE_INIT.
1400 g_static_private_init (GStaticPrivate *private_key)
1402 private_key->index = 0;
1406 * g_static_private_get:
1407 * @private_key: a #GStaticPrivate.
1408 * @Returns: the corresponding pointer.
1410 * Works like g_private_get() only for a #GStaticPrivate.
1412 * This function works even if g_thread_init() has not yet been called.
1415 g_static_private_get (GStaticPrivate *private_key)
1417 GRealThread *self = (GRealThread*) g_thread_self ();
1419 gpointer ret = NULL;
1421 LOCK_PRIVATE_DATA (self);
1423 array = self->private_data;
1425 if (array && private_key->index != 0 && private_key->index <= array->len)
1426 ret = g_array_index (array, GStaticPrivateNode,
1427 private_key->index - 1).data;
1429 UNLOCK_PRIVATE_DATA (self);
1434 * g_static_private_set:
1435 * @private_key: a #GStaticPrivate.
1436 * @data: the new pointer.
1437 * @notify: a function to be called with the pointer whenever the
1438 * current thread ends or sets this pointer again.
1440 * Sets the pointer keyed to @private_key for the current thread and
1441 * the function @notify to be called with that pointer (%NULL or
1442 * non-%NULL), whenever the pointer is set again or whenever the
1443 * current thread ends.
1445 * This function works even if g_thread_init() has not yet been called.
1446 * If g_thread_init() is called later, the @data keyed to @private_key
1447 * will be inherited only by the main thread, i.e. the one that called
1450 * <note><para>@notify is used quite differently from @destructor in
1451 * g_private_new().</para></note>
1454 g_static_private_set (GStaticPrivate *private_key,
1456 GDestroyNotify notify)
1458 GRealThread *self = (GRealThread*) g_thread_self ();
1460 static guint next_index = 0;
1461 GStaticPrivateNode *node;
1462 gpointer ddata = NULL;
1463 GDestroyNotify ddestroy = NULL;
1465 if (!private_key->index)
1469 if (!private_key->index)
1471 if (g_thread_free_indices)
1473 private_key->index =
1474 GPOINTER_TO_UINT (g_thread_free_indices->data);
1475 g_thread_free_indices =
1476 g_slist_delete_link (g_thread_free_indices,
1477 g_thread_free_indices);
1480 private_key->index = ++next_index;
1483 G_UNLOCK (g_thread);
1486 LOCK_PRIVATE_DATA (self);
1488 array = self->private_data;
1491 array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
1492 self->private_data = array;
1495 if (private_key->index > array->len)
1496 g_array_set_size (array, private_key->index);
1498 node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
1501 ddestroy = node->destroy;
1504 node->destroy = notify;
1506 UNLOCK_PRIVATE_DATA (self);
1513 * g_static_private_free:
1514 * @private_key: a #GStaticPrivate to be freed.
1516 * Releases all resources allocated to @private_key.
1518 * You don't have to call this functions for a #GStaticPrivate with an
1519 * unbounded lifetime, i.e. objects declared 'static', but if you have
1520 * a #GStaticPrivate as a member of a structure and the structure is
1521 * freed, you should also free the #GStaticPrivate.
1524 g_static_private_free (GStaticPrivate *private_key)
1526 guint idx = private_key->index;
1527 GRealThread *thread, *next;
1528 GArray *garbage = NULL;
1533 private_key->index = 0;
1537 thread = g_thread_all_threads;
1539 for (thread = g_thread_all_threads; thread; thread = next)
1543 next = thread->next;
1545 LOCK_PRIVATE_DATA (thread);
1547 array = thread->private_data;
1549 if (array && idx <= array->len)
1551 GStaticPrivateNode *node = &g_array_index (array,
1554 gpointer ddata = node->data;
1555 GDestroyNotify ddestroy = node->destroy;
1558 node->destroy = NULL;
1562 /* defer non-trivial destruction til after we've finished
1563 * iterating, since we must continue to hold the lock */
1564 if (garbage == NULL)
1565 garbage = g_array_new (FALSE, TRUE,
1566 sizeof (GStaticPrivateNode));
1568 g_array_set_size (garbage, garbage->len + 1);
1570 node = &g_array_index (garbage, GStaticPrivateNode,
1573 node->destroy = ddestroy;
1577 UNLOCK_PRIVATE_DATA (thread);
1579 g_thread_free_indices = g_slist_prepend (g_thread_free_indices,
1580 GUINT_TO_POINTER (idx));
1581 G_UNLOCK (g_thread);
1587 for (i = 0; i < garbage->len; i++)
1589 GStaticPrivateNode *node;
1591 node = &g_array_index (garbage, GStaticPrivateNode, i);
1592 node->destroy (node->data);
1595 g_array_free (garbage, TRUE);
1599 /* GThread Extra Functions {{{1 ------------------------------------------- */
1601 g_thread_cleanup (gpointer data)
1605 GRealThread* thread = data;
1608 LOCK_PRIVATE_DATA (thread);
1609 array = thread->private_data;
1610 thread->private_data = NULL;
1611 UNLOCK_PRIVATE_DATA (thread);
1617 for (i = 0; i < array->len; i++ )
1619 GStaticPrivateNode *node =
1620 &g_array_index (array, GStaticPrivateNode, i);
1622 node->destroy (node->data);
1624 g_array_free (array, TRUE);
1627 /* We only free the thread structure, if it isn't joinable. If
1628 it is, the structure is freed in g_thread_join */
1629 if (!thread->thread.joinable)
1634 for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
1641 g_thread_all_threads = t->next;
1645 G_UNLOCK (g_thread);
1647 /* Just to make sure, this isn't used any more */
1648 g_system_thread_assign (thread->system_thread, zero_thread);
1654 #define G_NSEC_PER_SEC 1000000000
1659 return g_get_monotonic_time () * 1000;
1663 g_thread_create_proxy (gpointer data)
1665 GRealThread* thread = data;
1669 /* This has to happen before G_LOCK, as that might call g_thread_self */
1670 g_private_set (&g_thread_specific_private, data);
1672 /* the lock makes sure, that thread->system_thread is written,
1673 before thread->thread.func is called. See g_thread_create. */
1675 G_UNLOCK (g_thread);
1677 thread->retval = thread->thread.func (thread->thread.data);
1684 * @func: a function to execute in the new thread
1685 * @data: an argument to supply to the new thread
1686 * @joinable: should this thread be joinable?
1687 * @error: return location for error, or %NULL
1689 * This function creates a new thread.
1691 * If @joinable is %TRUE, you can wait for this threads termination
1692 * calling g_thread_join(). Otherwise the thread will just disappear
1693 * when it terminates.
1695 * The new thread executes the function @func with the argument @data.
1696 * If the thread was created successfully, it is returned.
1698 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
1699 * The error is set, if and only if the function returns %NULL.
1701 * Returns: the new #GThread on success
1704 g_thread_create (GThreadFunc func,
1709 return g_thread_create_with_stack_size (func, data, joinable, 0, error);
1713 * g_thread_create_with_stack_size:
1714 * @func: a function to execute in the new thread.
1715 * @data: an argument to supply to the new thread.
1716 * @joinable: should this thread be joinable?
1717 * @stack_size: a stack size for the new thread.
1718 * @error: return location for error.
1719 * @Returns: the new #GThread on success.
1721 * This function creates a new thread. If the underlying thread
1722 * implementation supports it, the thread gets a stack size of
1723 * @stack_size or the default value for the current platform, if
1726 * If @joinable is %TRUE, you can wait for this threads termination
1727 * calling g_thread_join(). Otherwise the thread will just disappear
1728 * when it terminates.
1730 * The new thread executes the function @func with the argument @data.
1731 * If the thread was created successfully, it is returned.
1733 * @error can be %NULL to ignore errors, or non-%NULL to report errors.
1734 * The error is set, if and only if the function returns %NULL.
1737 * Only use g_thread_create_with_stack_size() if you really can't use
1738 * g_thread_create() instead. g_thread_create() does not take
1739 * @stack_size, as it should only be used in cases in which it is
1744 g_thread_create_with_stack_size (GThreadFunc func,
1750 GRealThread* result;
1751 GError *local_error = NULL;
1752 g_return_val_if_fail (func, NULL);
1754 result = g_new0 (GRealThread, 1);
1756 result->thread.joinable = joinable;
1757 result->thread.func = func;
1758 result->thread.data = data;
1759 result->private_data = NULL;
1761 g_system_thread_create (g_thread_create_proxy, result,
1762 stack_size, joinable,
1763 &result->system_thread, &local_error);
1766 result->next = g_thread_all_threads;
1767 g_thread_all_threads = result;
1769 G_UNLOCK (g_thread);
1773 g_propagate_error (error, local_error);
1778 return (GThread*) result;
1782 * g_thread_create_full:
1783 * @func: a function to execute in the new thread.
1784 * @data: an argument to supply to the new thread.
1785 * @stack_size: a stack size for the new thread.
1786 * @joinable: should this thread be joinable?
1788 * @priority: ignored
1789 * @error: return location for error.
1790 * @Returns: the new #GThread on success.
1792 * This function creates a new thread.
1794 * Deprecated:2.32: The @bound and @priority arguments are now ignored.
1795 * Use g_thread_create() or g_thread_create_with_stack_size() instead.
1798 g_thread_create_full (GThreadFunc func,
1803 GThreadPriority priority,
1806 return g_thread_create_with_stack_size (func, data, joinable, stack_size, error);
1811 * @retval: the return value of this thread.
1813 * Exits the current thread. If another thread is waiting for that
1814 * thread using g_thread_join() and the current thread is joinable, the
1815 * waiting thread will be woken up and get @retval as the return value
1816 * of g_thread_join(). If the current thread is not joinable, @retval
1817 * is ignored. Calling
1820 * g_thread_exit (retval);
1823 * is equivalent to returning @retval from the function @func, as given
1824 * to g_thread_create().
1826 * <note><para>Never call g_thread_exit() from within a thread of a
1827 * #GThreadPool, as that will mess up the bookkeeping and lead to funny
1828 * and unwanted results.</para></note>
1831 g_thread_exit (gpointer retval)
1833 GRealThread* real = (GRealThread*) g_thread_self ();
1834 real->retval = retval;
1836 g_system_thread_exit ();
1841 * @thread: a #GThread to be waited for.
1842 * @Returns: the return value of the thread.
1844 * Waits until @thread finishes, i.e. the function @func, as given to
1845 * g_thread_create(), returns or g_thread_exit() is called by @thread.
1846 * All resources of @thread including the #GThread struct are released.
1847 * @thread must have been created with @joinable=%TRUE in
1848 * g_thread_create(). The value returned by @func or given to
1849 * g_thread_exit() by @thread is returned by this function.
1852 g_thread_join (GThread* thread)
1854 GRealThread* real = (GRealThread*) thread;
1858 g_return_val_if_fail (thread, NULL);
1859 g_return_val_if_fail (thread->joinable, NULL);
1860 g_return_val_if_fail (!g_system_thread_equal (&real->system_thread, &zero_thread), NULL);
1862 g_system_thread_join (&real->system_thread);
1864 retval = real->retval;
1867 for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
1869 if (t == (GRealThread*) thread)
1874 g_thread_all_threads = t->next;
1878 G_UNLOCK (g_thread);
1880 /* Just to make sure, this isn't used any more */
1881 thread->joinable = 0;
1882 g_system_thread_assign (real->system_thread, zero_thread);
1884 /* the thread structure for non-joinable threads is freed upon
1885 thread end. We free the memory here. This will leave a loose end,
1886 if a joinable thread is not joined. */
1894 * g_thread_set_priority:
1895 * @thread: a #GThread.
1896 * @priority: ignored
1898 * This function does nothing.
1900 * Deprecated:2.32: Thread priorities no longer have any effect.
1903 g_thread_set_priority (GThread *thread,
1904 GThreadPriority priority)
1910 * @Returns: the current thread.
1912 * This functions returns the #GThread corresponding to the calling
1916 g_thread_self (void)
1918 GRealThread* thread = g_private_get (&g_thread_specific_private);
1922 /* If no thread data is available, provide and set one. This
1923 can happen for the main thread and for threads, that are not
1925 thread = g_new0 (GRealThread, 1);
1926 thread->thread.joinable = FALSE; /* This is a save guess */
1927 thread->thread.func = NULL;
1928 thread->thread.data = NULL;
1929 thread->private_data = NULL;
1931 g_system_thread_self (&thread->system_thread);
1933 g_private_set (&g_thread_specific_private, thread);
1936 thread->next = g_thread_all_threads;
1937 g_thread_all_threads = thread;
1938 G_UNLOCK (g_thread);
1941 return (GThread*)thread;
1944 /* GStaticRWLock {{{1 ----------------------------------------------------- */
1949 * The #GStaticRWLock struct represents a read-write lock. A read-write
1950 * lock can be used for protecting data that some portions of code only
1951 * read from, while others also write. In such situations it is
1952 * desirable that several readers can read at once, whereas of course
1953 * only one writer may write at a time. Take a look at the following
1957 * <title>An array with access functions</title>
1959 * GStaticRWLock rwlock = G_STATIC_RW_LOCK_INIT;
1963 * my_array_get (guint index)
1965 * gpointer retval = NULL;
1970 * g_static_rw_lock_reader_lock (&rwlock);
1971 * if (index < array->len)
1972 * retval = g_ptr_array_index (array, index);
1973 * g_static_rw_lock_reader_unlock (&rwlock);
1979 * my_array_set (guint index, gpointer data)
1981 * g_static_rw_lock_writer_lock (&rwlock);
1984 * array = g_ptr_array_new (<!-- -->);
1986 * if (index >= array->len)
1987 * g_ptr_array_set_size (array, index+1);
1988 * g_ptr_array_index (array, index) = data;
1990 * g_static_rw_lock_writer_unlock (&rwlock);
1995 * This example shows an array which can be accessed by many readers
1996 * (the <function>my_array_get()</function> function) simultaneously,
1997 * whereas the writers (the <function>my_array_set()</function>
1998 * function) will only be allowed once at a time and only if no readers
1999 * currently access the array. This is because of the potentially
2000 * dangerous resizing of the array. Using these functions is fully
2001 * multi-thread safe now.
2003 * Most of the time, writers should have precedence over readers. That
2004 * means, for this implementation, that as soon as a writer wants to
2005 * lock the data, no other reader is allowed to lock the data, whereas,
2006 * of course, the readers that already have locked the data are allowed
2007 * to finish their operation. As soon as the last reader unlocks the
2008 * data, the writer will lock it.
2010 * Even though #GStaticRWLock is not opaque, it should only be used
2011 * with the following functions.
2013 * All of the <function>g_static_rw_lock_*</function> functions can be
2014 * used even if g_thread_init() has not been called. Then they do
2015 * nothing, apart from <function>g_static_rw_lock_*_trylock</function>,
2016 * which does nothing but returning %TRUE.
2018 * <note><para>A read-write lock has a higher overhead than a mutex. For
2019 * example, both g_static_rw_lock_reader_lock() and
2020 * g_static_rw_lock_reader_unlock() have to lock and unlock a
2021 * #GStaticMutex, so it takes at least twice the time to lock and unlock
2022 * a #GStaticRWLock that it does to lock and unlock a #GStaticMutex. So
2023 * only data structures that are accessed by multiple readers, and which
2024 * keep the lock for a considerable time justify a #GStaticRWLock. The
2025 * above example most probably would fare better with a
2026 * #GStaticMutex.</para></note>
2030 * G_STATIC_RW_LOCK_INIT:
2032 * A #GStaticRWLock must be initialized with this macro before it can
2033 * be used. This macro can used be to initialize a variable, but it
2034 * cannot be assigned to a variable. In that case you have to use
2035 * g_static_rw_lock_init().
2038 * GStaticRWLock my_lock = G_STATIC_RW_LOCK_INIT;
2043 * g_static_rw_lock_init:
2044 * @lock: a #GStaticRWLock to be initialized.
2046 * A #GStaticRWLock must be initialized with this function before it
2047 * can be used. Alternatively you can initialize it with
2048 * #G_STATIC_RW_LOCK_INIT.
2051 g_static_rw_lock_init (GStaticRWLock* lock)
2053 static const GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
2055 g_return_if_fail (lock);
2061 g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
2064 *cond = g_cond_new ();
2065 g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
2069 g_static_rw_lock_signal (GStaticRWLock* lock)
2071 if (lock->want_to_write && lock->write_cond)
2072 g_cond_signal (lock->write_cond);
2073 else if (lock->want_to_read && lock->read_cond)
2074 g_cond_broadcast (lock->read_cond);
2078 * g_static_rw_lock_reader_lock:
2079 * @lock: a #GStaticRWLock to lock for reading.
2081 * Locks @lock for reading. There may be unlimited concurrent locks for
2082 * reading of a #GStaticRWLock at the same time. If @lock is already
2083 * locked for writing by another thread or if another thread is already
2084 * waiting to lock @lock for writing, this function will block until
2085 * @lock is unlocked by the other writing thread and no other writing
2086 * threads want to lock @lock. This lock has to be unlocked by
2087 * g_static_rw_lock_reader_unlock().
2089 * #GStaticRWLock is not recursive. It might seem to be possible to
2090 * recursively lock for reading, but that can result in a deadlock, due
2091 * to writer preference.
2094 g_static_rw_lock_reader_lock (GStaticRWLock* lock)
2096 g_return_if_fail (lock);
2098 if (!g_threads_got_initialized)
2101 g_static_mutex_lock (&lock->mutex);
2102 lock->want_to_read++;
2103 while (lock->have_writer || lock->want_to_write)
2104 g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
2105 lock->want_to_read--;
2106 lock->read_counter++;
2107 g_static_mutex_unlock (&lock->mutex);
2111 * g_static_rw_lock_reader_trylock:
2112 * @lock: a #GStaticRWLock to lock for reading.
2113 * @Returns: %TRUE, if @lock could be locked for reading.
2115 * Tries to lock @lock for reading. If @lock is already locked for
2116 * writing by another thread or if another thread is already waiting to
2117 * lock @lock for writing, immediately returns %FALSE. Otherwise locks
2118 * @lock for reading and returns %TRUE. This lock has to be unlocked by
2119 * g_static_rw_lock_reader_unlock().
2122 g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
2124 gboolean ret_val = FALSE;
2126 g_return_val_if_fail (lock, FALSE);
2128 if (!g_threads_got_initialized)
2131 g_static_mutex_lock (&lock->mutex);
2132 if (!lock->have_writer && !lock->want_to_write)
2134 lock->read_counter++;
2137 g_static_mutex_unlock (&lock->mutex);
2142 * g_static_rw_lock_reader_unlock:
2143 * @lock: a #GStaticRWLock to unlock after reading.
2145 * Unlocks @lock. If a thread waits to lock @lock for writing and all
2146 * locks for reading have been unlocked, the waiting thread is woken up
2147 * and can lock @lock for writing.
2150 g_static_rw_lock_reader_unlock (GStaticRWLock* lock)
2152 g_return_if_fail (lock);
2154 if (!g_threads_got_initialized)
2157 g_static_mutex_lock (&lock->mutex);
2158 lock->read_counter--;
2159 if (lock->read_counter == 0)
2160 g_static_rw_lock_signal (lock);
2161 g_static_mutex_unlock (&lock->mutex);
2165 * g_static_rw_lock_writer_lock:
2166 * @lock: a #GStaticRWLock to lock for writing.
2168 * Locks @lock for writing. If @lock is already locked for writing or
2169 * reading by other threads, this function will block until @lock is
2170 * completely unlocked and then lock @lock for writing. While this
2171 * functions waits to lock @lock, no other thread can lock @lock for
2172 * reading. When @lock is locked for writing, no other thread can lock
2173 * @lock (neither for reading nor writing). This lock has to be
2174 * unlocked by g_static_rw_lock_writer_unlock().
2177 g_static_rw_lock_writer_lock (GStaticRWLock* lock)
2179 g_return_if_fail (lock);
2181 if (!g_threads_got_initialized)
2184 g_static_mutex_lock (&lock->mutex);
2185 lock->want_to_write++;
2186 while (lock->have_writer || lock->read_counter)
2187 g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
2188 lock->want_to_write--;
2189 lock->have_writer = TRUE;
2190 g_static_mutex_unlock (&lock->mutex);
2194 * g_static_rw_lock_writer_trylock:
2195 * @lock: a #GStaticRWLock to lock for writing.
2196 * @Returns: %TRUE, if @lock could be locked for writing.
2198 * Tries to lock @lock for writing. If @lock is already locked (for
2199 * either reading or writing) by another thread, it immediately returns
2200 * %FALSE. Otherwise it locks @lock for writing and returns %TRUE. This
2201 * lock has to be unlocked by g_static_rw_lock_writer_unlock().
2204 g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
2206 gboolean ret_val = FALSE;
2208 g_return_val_if_fail (lock, FALSE);
2210 if (!g_threads_got_initialized)
2213 g_static_mutex_lock (&lock->mutex);
2214 if (!lock->have_writer && !lock->read_counter)
2216 lock->have_writer = TRUE;
2219 g_static_mutex_unlock (&lock->mutex);
2224 * g_static_rw_lock_writer_unlock:
2225 * @lock: a #GStaticRWLock to unlock after writing.
2227 * Unlocks @lock. If a thread is waiting to lock @lock for writing and
2228 * all locks for reading have been unlocked, the waiting thread is
2229 * woken up and can lock @lock for writing. If no thread is waiting to
2230 * lock @lock for writing, and some thread or threads are waiting to
2231 * lock @lock for reading, the waiting threads are woken up and can
2232 * lock @lock for reading.
2235 g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
2237 g_return_if_fail (lock);
2239 if (!g_threads_got_initialized)
2242 g_static_mutex_lock (&lock->mutex);
2243 lock->have_writer = FALSE;
2244 g_static_rw_lock_signal (lock);
2245 g_static_mutex_unlock (&lock->mutex);
2249 * g_static_rw_lock_free:
2250 * @lock: a #GStaticRWLock to be freed.
2252 * Releases all resources allocated to @lock.
2254 * You don't have to call this functions for a #GStaticRWLock with an
2255 * unbounded lifetime, i.e. objects declared 'static', but if you have
2256 * a #GStaticRWLock as a member of a structure, and the structure is
2257 * freed, you should also free the #GStaticRWLock.
2260 g_static_rw_lock_free (GStaticRWLock* lock)
2262 g_return_if_fail (lock);
2264 if (lock->read_cond)
2266 g_cond_free (lock->read_cond);
2267 lock->read_cond = NULL;
2269 if (lock->write_cond)
2271 g_cond_free (lock->write_cond);
2272 lock->write_cond = NULL;
2274 g_static_mutex_free (&lock->mutex);
2277 /* Unsorted {{{1 ---------------------------------------------------------- */
2281 * @thread_func: function to call for all GThread structures
2282 * @user_data: second argument to @thread_func
2284 * Call @thread_func on all existing #GThread structures. Note that
2285 * threads may decide to exit while @thread_func is running, so
2286 * without intimate knowledge about the lifetime of foreign threads,
2287 * @thread_func shouldn't access the GThread* pointer passed in as
2288 * first argument. However, @thread_func will not be called for threads
2289 * which are known to have exited already.
2291 * Due to thread lifetime checks, this function has an execution complexity
2292 * which is quadratic in the number of existing threads.
2297 g_thread_foreach (GFunc thread_func,
2300 GSList *slist = NULL;
2301 GRealThread *thread;
2302 g_return_if_fail (thread_func != NULL);
2303 /* snapshot the list of threads for iteration */
2305 for (thread = g_thread_all_threads; thread; thread = thread->next)
2306 slist = g_slist_prepend (slist, thread);
2307 G_UNLOCK (g_thread);
2308 /* walk the list, skipping non-existent threads */
2311 GSList *node = slist;
2313 /* check whether the current thread still exists */
2315 for (thread = g_thread_all_threads; thread; thread = thread->next)
2316 if (thread == node->data)
2318 G_UNLOCK (g_thread);
2320 thread_func (thread, user_data);
2321 g_slist_free_1 (node);
2326 * g_thread_get_initialized:
2328 * Indicates if g_thread_init() has been called.
2330 * Returns: %TRUE if threads have been initialized.
2335 g_thread_get_initialized ()
2337 return g_thread_supported ();
2343 * Creates a new #GMutex.
2345 * Returns: a newly allocated #GMutex. Use g_mutex_free() to free
2352 mutex = g_slice_new (GMutex);
2353 g_mutex_init (mutex);
2362 * Destroys a @mutex that has been created with g_mutex_new().
2364 * <note>Calling g_mutex_free() on a locked mutex may result
2365 * in undefined behaviour.</note>
2368 g_mutex_free (GMutex *mutex)
2370 g_mutex_clear (mutex);
2371 g_slice_free (GMutex, mutex);
2377 * Creates a new #GCond.
2379 * Returns: a newly allocated #GCond. Free with g_cond_free()
2386 cond = g_slice_new (GCond);
2396 * Destroys a #GCond that has been created with g_cond_new().
2399 g_cond_free (GCond *cond)
2401 g_cond_clear (cond);
2402 g_slice_free (GCond, cond);
2407 * @destructor: a function to destroy the data keyed to
2408 * the #GPrivate when a thread ends
2410 * Creates a new #GPrivate. If @destructor is non-%NULL, it is a
2411 * pointer to a destructor function. Whenever a thread ends and the
2412 * corresponding pointer keyed to this instance of #GPrivate is
2413 * non-%NULL, the destructor is called with this pointer as the
2417 * #GStaticPrivate is a better choice for most uses.
2420 * <note><para>@destructor is used quite differently from @notify in
2421 * g_static_private_set().</para></note>
2423 * <note><para>A #GPrivate cannot be freed. Reuse it instead, if you
2424 * can, to avoid shortage, or use #GStaticPrivate.</para></note>
2426 * <note><para>This function will abort if g_thread_init() has not been
2427 * called yet.</para></note>
2429 * Returns: a newly allocated #GPrivate
2432 g_private_new (GDestroyNotify notify)
2436 key = g_slice_new (GPrivate);
2437 g_private_init (key, notify);
2442 GThreadFunctions g_thread_functions_for_glib_use =