GDK_THREADS_ENTER()

#define             GDK_THREADS_ENTER()

This macro marks the beginning of a critical section in which GDK and GTK+ functions can be called safely and without causing race conditions. Only one thread at a time can be in such a critial section. The macro expands to a no-op if G_THREADS_ENABLED has not been defined. Typically gdk_threads_enter() should be used instead of this macro.

GDK_THREADS_LEAVE()

#define             GDK_THREADS_LEAVE()

This macro marks the end of a critical section begun with GDK_THREADS_ENTER.

gdk_threads_init ()

void                gdk_threads_init                    (void);

Initializes GDK so that it can be used from multiple threads in conjunction with gdk_threads_enter() and gdk_threads_leave(). g_thread_init() must be called previous to this function.

This call must be made before any use of the main loop from GTK+; to be safe, call it before gtk_init().

gdk_threads_enter ()

void                gdk_threads_enter                   (void);

This macro marks the beginning of a critical section in which GDK and GTK+ functions can be called safely and without causing race conditions. Only one thread at a time can be in such a critial section.

gdk_threads_leave ()

void                gdk_threads_leave                   (void);

Leaves a critical region begun with gdk_threads_enter().

gdk_threads_mutex

extern GMutex *gdk_threads_mutex; /* private */

The GMutex used to implement the critical region for gdk_threads_enter()/gdk_threads_leave().

gdk_threads_set_lock_functions ()

void                gdk_threads_set_lock_functions      (GCallback enter_fn,
                                                         GCallback leave_fn);

Allows the application to replace the standard method that GDK uses to protect its data structures. Normally, GDK creates a single GMutex that is locked by gdk_threads_enter(), and released by gdk_threads_leave(); using this function an application provides, instead, a function enter_fn that is called by gdk_threads_enter() and a function leave_fn that is called by gdk_threads_leave().

The functions must provide at least same locking functionality as the default implementation, but can also do extra application specific processing.

As an example, consider an application that has its own recursive lock that when held, holds the GTK+ lock as well. When GTK+ unlocks the GTK+ lock when entering a recursive main loop, the application must temporarily release its lock as well.

Most threaded GTK+ apps won't need to use this method.

This method must be called before gdk_threads_init(), and cannot be called multiple times.

Since 2.4

gdk_threads_add_idle ()

guint               gdk_threads_add_idle                (GSourceFunc function,
                                                         gpointer data);

A wrapper for the common usage of gdk_threads_add_idle_full() assigning the default priority, G_PRIORITY_DEFAULT_IDLE.

See gdk_threads_add_idle_full().

Since 2.12

gdk_threads_add_idle_full ()

guint               gdk_threads_add_idle_full           (gint priority,
                                                         GSourceFunc function,
                                                         gpointer data,
                                                         GDestroyNotify notify);

Adds a function to be called whenever there are no higher priority events pending. If the function returns FALSE it is automatically removed from the list of event sources and will not be called again.

This variant of g_idle_add_full() calls function with the GDK lock held. It can be thought of a MT-safe version for GTK+ widgets for the following use case, where you have to worry about idle_callback() running in thread A and accessing self after it has been finalized in thread B:

static gboolean
idle_callback (gpointer data)
{
   // gdk_threads_enter(); would be needed for g_idle_add()
   
   SomeWidget *self = data;
   /* do stuff with self */
   
   self->idle_id = 0;
   
   // gdk_threads_leave(); would be needed for g_idle_add()
   return FALSE;
}
 
static void
some_widget_do_stuff_later (SomeWidget *self)
{
   self->idle_id = gdk_threads_add_idle (idle_callback, self)
   // using g_idle_add() here would require thread protection in the callback
}
 
static void
some_widget_finalize (GObject *object)
{
   SomeWidget *self = SOME_WIDGET (object);
   if (self->idle_id)
     g_source_remove (self->idle_id);
   G_OBJECT_CLASS (parent_class)->finalize (object);
}

Since 2.12

gdk_threads_add_timeout ()

guint               gdk_threads_add_timeout             (guint interval,
                                                         GSourceFunc function,
                                                         gpointer data);

A wrapper for the common usage of gdk_threads_add_timeout_full() assigning the default priority, G_PRIORITY_DEFAULT.

See gdk_threads_add_timeout_full().

Since 2.12

gdk_threads_add_timeout_full ()

guint               gdk_threads_add_timeout_full        (gint priority,
                                                         guint interval,
                                                         GSourceFunc function,
                                                         gpointer data,
                                                         GDestroyNotify notify);

Sets a function to be called at regular intervals holding the GDK lock, with the given priority. The function is called repeatedly until it returns FALSE, at which point the timeout is automatically destroyed and the function will not be called again. The notify function is called when the timeout is destroyed. The first call to the function will be at the end of the first interval.

Note that timeout functions may be delayed, due to the processing of other event sources. Thus they should not be relied on for precise timing. After each call to the timeout function, the time of the next timeout is recalculated based on the current time and the given interval (it does not try to 'catch up' time lost in delays).

This variant of g_timeout_add_full() can be thought of a MT-safe version for GTK+ widgets for the following use case:

static gboolean timeout_callback (gpointer data)
{
   SomeWidget *self = data;
   
   /* do stuff with self */
   
   self->timeout_id = 0;
   
   return FALSE;
}
 
static void some_widget_do_stuff_later (SomeWidget *self)
{
   self->timeout_id = g_timeout_add (timeout_callback, self)
}
 
static void some_widget_finalize (GObject *object)
{
   SomeWidget *self = SOME_WIDGET(object);
   
   if (self->timeout_id)
     g_source_remove (self->timeout_id);
   
   G_OBJECT_CLASS (parent_class)->finalize (object);
}

Since 2.12