* facilities for one-time initialization (#GOnce, g_once_init_enter()).
* Finally there are primitives to create and manage threads (#GThread).
*
- * The threading system is initialized with g_thread_init().
- * You may call any other GLib functions in the main thread before
- * g_thread_init() as long as g_thread_init() is not called from
- * a GLib callback, or with any locks held. However, many libraries
- * above GLib do not support late initialization of threads, so
- * doing this should be avoided if possible.
- *
- * Please note that since version 2.24 the GObject initialization
- * function g_type_init() initializes threads. Since 2.32, creating
- * a mainloop will do so too. As a consequence, most applications,
- * including those using GTK+, will run with threads enabled.
- *
- * After calling g_thread_init(), GLib is completely thread safe
- * (all global data is automatically locked), but individual data
- * structure instances are not automatically locked for performance
- * reasons. So, for example you must coordinate accesses to the same
- * #GHashTable from multiple threads. The two notable exceptions from
- * this rule are #GMainLoop and #GAsyncQueue, which <emphasis>are</emphasis>
- * threadsafe and need no further application-level locking to be
- * accessed from multiple threads.
- */
-
-/**
- * G_THREADS_IMPL_POSIX:
- *
- * This macro is defined if POSIX style threads are used.
- */
-
-/**
- * G_THREADS_IMPL_WIN32:
- *
- * This macro is defined if Windows style threads are used.
+ * The GLib threading system used to be initialized with g_thread_init().
+ * This is no longer necessary. Since version 2.32, the GLib threading
+ * system is automatically initialized at the start of your program,
+ * and all thread-creation functions and synchronization primitives
+ * are available right away. It is still possible to do thread-unsafe
+ * initialization and setup at the beginning of your program, before
+ * creating the first threads.
+ *
+ * GLib is internally completely thread-safe (all global data is
+ * automatically locked), but individual data structure instances are
+ * not automatically locked for performance reasons. For example,
+ * you must coordinate accesses to the same #GHashTable from multiple
+ * threads. The two notable exceptions from this rule are #GMainLoop
+ * and #GAsyncQueue, which <emphasis>are</emphasis> thread-safe and
+ * need no further application-level locking to be accessed from
+ * multiple threads. Most refcounting functions such as g_object_ref()
+ * are also thread-safe.
*/
/* G_LOCK Documentation {{{1 ---------------------------------------------- */
*
* It is easy to see that this won't work in a multi-threaded
* application. There current_number must be protected against shared
- * access. A first naive implementation would be:
- *
- * <example>
- * <title>The wrong way to write a thread-safe function</title>
- * <programlisting>
- * int
- * give_me_next_number (void)
- * {
- * static int current_number = 0;
- * int ret_val;
- * static GMutex * mutex = NULL;
- *
- * if (!mutex) mutex = g_mutex_new (<!-- -->);
- *
- * g_mutex_lock (mutex);
- * ret_val = current_number = calc_next_number (current_number);
- * g_mutex_unlock (mutex);
- *
- * return ret_val;
- * }
- * </programlisting>
- * </example>
- *
- * This looks like it would work, but there is a race condition while
- * constructing the mutex and this code cannot work reliable. Please do
- * not use such constructs in your own programs! One working solution
- * is:
+ * access. A #GMutex can be used as a solution to this problem:
*
* <example>
- * <title>A correct thread-safe function</title>
- * <programlisting>
- * static GMutex *give_me_next_number_mutex = NULL;
- *
- * /<!-- -->* this function must be called before any call to
- * * give_me_next_number(<!-- -->)
- * *
- * * it must be called exactly once.
- * *<!-- -->/
- * void
- * init_give_me_next_number (void)
- * {
- * g_assert (give_me_next_number_mutex == NULL);
- * give_me_next_number_mutex = g_mutex_new (<!-- -->);
- * }
- *
- * int
- * give_me_next_number (void)
- * {
- * static int current_number = 0;
- * int ret_val;
- *
- * g_mutex_lock (give_me_next_number_mutex);
- * ret_val = current_number = calc_next_number (current_number);
- * g_mutex_unlock (give_me_next_number_mutex);
- *
- * return ret_val;
- * }
- * </programlisting>
- * </example>
- *
- * If a #GMutex is allocated in static storage then it can be used
- * without initialisation. Otherwise, you should call g_mutex_init() on
- * it and g_mutex_clear() when done.
- *
- * A statically initialized #GMutex provides an even simpler and safer
- * way of doing this:
- *
- * <example>
- * <title>Using a statically allocated mutex</title>
+ * <title>Using GMutex to protected a shared variable</title>
* <programlisting>
* int
* give_me_next_number (void)
* </programlisting>
* </example>
*
+ * Notice that the #GMutex is not initialised to any particular value.
+ * Its placement in static storage ensures that it will be initialised
+ * to all-zeros, which is appropriate.
+ *
+ * If a #GMutex is placed in other contexts (eg: embedded in a struct)
+ * then it must be explicitly initialised using g_mutex_init().
+ *
* A #GMutex should only be accessed via <function>g_mutex_</function>
* functions.
*/
* is returned by g_thread_new() or g_thread_new_full(). You can
* obtain the #GThread struct representing the current thead by
* calling g_thread_self().
+ *
+ * The structure is opaque -- none of its fields may be directly
+ * accessed.
*/
/**
/* Local Data {{{1 -------------------------------------------------------- */
-gboolean g_threads_got_initialized = FALSE;
-GSystemThread zero_thread; /* This is initialized to all zero */
-
GMutex g_once_mutex;
static GCond g_once_cond;
static GSList *g_once_init_list = NULL;
G_LOCK_DEFINE_STATIC (g_thread_new);
-/* Initialisation {{{1 ---------------------------------------------------- */
-
-/**
- * g_thread_init:
- * @vtable: a function table of type #GThreadFunctions, that provides
- * the entry points to the thread system to be used. Since 2.32,
- * this parameter is ignored and should always be %NULL
- *
- * If you use GLib from more than one thread, you must initialize the
- * thread system by calling g_thread_init().
- *
- * Since version 2.24, calling g_thread_init() multiple times is allowed,
- * but nothing happens except for the first call.
- *
- * Since version 2.32, GLib does not support custom thread implementations
- * anymore and the @vtable parameter is ignored and you should pass %NULL.
- *
- * <note><para>g_thread_init() must not be called directly or indirectly
- * in a callback from GLib. Also no mutexes may be currently locked while
- * calling g_thread_init().</para></note>
- *
- * <note><para>To use g_thread_init() in your program, you have to link
- * with the libraries that the command <command>pkg-config --libs
- * gthread-2.0</command> outputs. This is not the case for all the
- * other thread-related functions of GLib. Those can be used without
- * having to link with the thread libraries.</para></note>
- */
-
-void
-g_thread_init_glib (void)
-{
- static gboolean already_done;
- GRealThread *main_thread;
-
- if (already_done)
- return;
-
- already_done = TRUE;
-
- /* We let the main thread (the one that calls g_thread_init) inherit
- * the static_private data set before calling g_thread_init
- */
- main_thread = (GRealThread*) g_thread_self ();
-
- /* setup the basic threading system */
- g_threads_got_initialized = TRUE;
- g_private_set (&g_thread_specific_private, main_thread);
- g_system_thread_self (&main_thread->system_thread);
-
- /* accomplish log system initialization to enable messaging */
- _g_messages_thread_init_nomessage ();
-}
-
-/**
- * g_thread_get_initialized:
- *
- * Indicates if g_thread_init() has been called.
- *
- * Returns: %TRUE if threads have been initialized.
- *
- * Since: 2.20
- */
-gboolean
-g_thread_get_initialized (void)
-{
- return g_thread_supported ();
-}
-
/* GOnce {{{1 ------------------------------------------------------------- */
/**
* Since: 2.14
*/
gboolean
-g_once_init_enter_impl (volatile gsize *value_location)
+(g_once_init_enter) (volatile void *pointer)
{
+ volatile gsize *value_location = pointer;
gboolean need_init = FALSE;
g_mutex_lock (&g_once_mutex);
if (g_atomic_pointer_get (value_location) == NULL)
* g_once_init_leave:
* @value_location: location of a static initializable variable
* containing 0
- * @initialization_value: new non-0 value for *@value_location
+ * @result: new non-0 value for *@value_location
*
* Counterpart to g_once_init_enter(). Expects a location of a static
* 0-initialized initialization variable, and an initialization value
* Since: 2.14
*/
void
-g_once_init_leave (volatile gsize *value_location,
- gsize initialization_value)
+(g_once_init_leave) (volatile void *pointer,
+ gsize result)
{
+ volatile gsize *value_location = pointer;
+
g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
- g_return_if_fail (initialization_value != 0);
+ g_return_if_fail (result != 0);
g_return_if_fail (g_once_init_list != NULL);
- g_atomic_pointer_set (value_location, initialization_value);
+ g_atomic_pointer_set (value_location, result);
g_mutex_lock (&g_once_mutex);
g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
g_cond_broadcast (&g_once_cond);
{
GRealThread* thread = data;
- g_static_private_cleanup (thread);
-
/* We only free the thread structure if it isn't joinable.
* If it is, the structure is freed in g_thread_join()
*/
if (!thread->thread.joinable)
- {
- if (thread->enumerable)
- g_enumerable_thread_remove (thread);
-
- /* Just to make sure, this isn't used any more */
- g_system_thread_assign (thread->system_thread, zero_thread);
- g_free (thread);
- }
+ g_free (thread);
}
}
/* This has to happen before G_LOCK, as that might call g_thread_self */
g_private_set (&g_thread_specific_private, data);
+ if (thread->setup_func)
+ thread->setup_func (thread);
+
/* The lock makes sure that thread->system_thread is written,
* before thread->thread.func is called. See g_thread_new_internal().
*/
* @joinable: should this thread be joinable?
* @error: return location for error
*
- * This function creates a new thread. The new thread starts by
- * invoking @func with the argument data. The thread will run
- * until @func returns or until g_thread_exit() is called.
+ * This function creates a new thread. The new thread starts by invoking
+ * @func with the argument data. The thread will run until @func returns
+ * or until g_thread_exit() is called from the new thread.
*
* The @name can be useful for discriminating threads in
* a debugger. Some systems restrict the length of @name to
* 16 bytes.
*
- * If @joinable is %TRUE, you can wait for this threads termination
+ * If @joinable is %TRUE, you can wait for this thread's termination
* calling g_thread_join(). Resources for a joinable thread are not
* fully released until g_thread_join() is called for that thread.
* Otherwise the thread will just disappear when it terminates.
* In most cases, using g_thread_new() (which doesn't take a
* @stack_size) is better.
*
- * If @joinable is %TRUE, you can wait for this threads termination
+ * If @joinable is %TRUE, you can wait for this thread's termination
* calling g_thread_join(). Resources for a joinable thread are not
* fully released until g_thread_join() is called for that thread.
* Otherwise the thread will just disappear when it terminates.
}
GThread *
-g_thread_new_internal (const gchar *name,
- GThreadFunc func,
- gpointer data,
- gboolean joinable,
- gsize stack_size,
- gboolean enumerable,
- GError **error)
+g_thread_new_internal (const gchar *name,
+ GThreadFunc func,
+ gpointer data,
+ gboolean joinable,
+ gsize stack_size,
+ GThreadSetup setup_func,
+ GError **error)
{
GRealThread *result;
GError *local_error = NULL;
result->thread.joinable = joinable;
result->thread.func = func;
result->thread.data = data;
- result->private_data = NULL;
- result->enumerable = enumerable;
+ result->setup_func = setup_func;
result->name = name;
G_LOCK (g_thread_new);
g_system_thread_create (g_thread_create_proxy, result,
stack_size, joinable,
&result->system_thread, &local_error);
- if (enumerable && !local_error)
- g_enumerable_thread_add (result);
G_UNLOCK (g_thread_new);
if (local_error)
g_return_val_if_fail (thread, NULL);
g_return_val_if_fail (thread->joinable, NULL);
- g_return_val_if_fail (!g_system_thread_equal (&real->system_thread, &zero_thread), NULL);
g_system_thread_join (&real->system_thread);
retval = real->retval;
- if (real->enumerable)
- g_enumerable_thread_remove (real);
-
/* Just to make sure, this isn't used any more */
thread->joinable = 0;
- g_system_thread_assign (real->system_thread, zero_thread);
/* the thread structure for non-joinable threads is freed upon
* thread end. We free the memory here. This will leave a loose end,
thread->thread.joinable = FALSE; /* This is a safe guess */
thread->thread.func = NULL;
thread->thread.data = NULL;
- thread->private_data = NULL;
- thread->enumerable = FALSE;
-
- g_system_thread_self (&thread->system_thread);
g_private_set (&g_thread_specific_private, thread);
}
return (GThread*)thread;
}
-/* GMutex {{{1 ------------------------------------------------------ */
-
-/**
- * g_mutex_new:
- *
- * Allocates and initializes a new #GMutex.
- *
- * Returns: a newly allocated #GMutex. Use g_mutex_free() to free
- */
-GMutex *
-g_mutex_new (void)
-{
- GMutex *mutex;
-
- mutex = g_slice_new (GMutex);
- g_mutex_init (mutex);
-
- return mutex;
-}
-
-/**
- * g_mutex_free:
- * @mutex: a #GMutex
- *
- * Destroys a @mutex that has been created with g_mutex_new().
- *
- * Calling g_mutex_free() on a locked mutex may result
- * in undefined behaviour.
- */
-void
-g_mutex_free (GMutex *mutex)
-{
- g_mutex_clear (mutex);
- g_slice_free (GMutex, mutex);
-}
-
-/* GCond {{{1 ------------------------------------------------------ */
-
-/**
- * g_cond_new:
- *
- * Allocates and initializes a new #GCond.
- *
- * Returns: a newly allocated #GCond. Free with g_cond_free()
- */
-GCond *
-g_cond_new (void)
-{
- GCond *cond;
-
- cond = g_slice_new (GCond);
- g_cond_init (cond);
-
- return cond;
-}
-
-/**
- * g_cond_free:
- * @cond: a #GCond
- *
- * Destroys a #GCond that has been created with g_cond_new().
- *
- * Calling g_cond_free() for a #GCond on which threads are
- * blocking leads to undefined behaviour.
- */
-void
-g_cond_free (GCond *cond)
-{
- g_cond_clear (cond);
- g_slice_free (GCond, cond);
-}
-
/* Epilogue {{{1 */
/* vim: set foldmethod=marker: */
projects / platform / upstream / glib.git / blobdiff