Commit 984258c6 authored by Allison Karlitskaya's avatar Allison Karlitskaya

GSettings: support emitting signals in threads

The thread-default context that was in effect at the time that the
GSettings was created will be used for emitting signals on that
GSettings.
parent 849684e5
......@@ -367,7 +367,7 @@ g_delayed_settings_backend_new (GSettingsBackend *backend,
delayed->priv->backend = g_object_ref (backend);
delayed->priv->owner = owner;
g_settings_backend_watch (delayed->priv->backend,
g_settings_backend_watch (delayed->priv->backend, NULL,
delayed_backend_changed,
delayed_backend_path_changed,
delayed_backend_keys_changed,
......
......@@ -146,6 +146,9 @@
struct _GSettingsPrivate
{
/* where the signals go... */
GMainContext *main_context;
GSettingsBackend *backend;
GSettingsSchema *schema;
gchar *schema_name;
......@@ -363,6 +366,7 @@ g_settings_constructed (GObject *object)
settings->priv->backend = g_settings_backend_get_with_context (settings->priv->context);
g_settings_backend_watch (settings->priv->backend,
settings->priv->main_context,
settings_backend_changed,
settings_backend_path_changed,
settings_backend_keys_changed,
......@@ -379,6 +383,13 @@ g_settings_init (GSettings *settings)
settings->priv = G_TYPE_INSTANCE_GET_PRIVATE (settings,
G_TYPE_SETTINGS,
GSettingsPrivate);
settings->priv->main_context = g_main_context_get_thread_default ();
if (settings->priv->main_context == NULL)
settings->priv->main_context = g_main_context_default ();
g_main_context_ref (settings->priv->main_context);
}
/**
......@@ -406,6 +417,7 @@ g_settings_delay (GSettings *settings)
settings->priv->backend = G_SETTINGS_BACKEND (settings->priv->delayed);
g_settings_backend_watch (settings->priv->backend,
settings->priv->main_context,
settings_backend_changed,
settings_backend_path_changed,
settings_backend_keys_changed,
......@@ -537,6 +549,7 @@ g_settings_finalize (GObject *object)
g_settings_backend_unwatch (settings->priv->backend, settings);
g_settings_backend_unsubscribe (settings->priv->backend,
settings->priv->path);
g_main_context_unref (settings->priv->main_context);
g_object_unref (settings->priv->backend);
g_object_unref (settings->priv->schema);
g_free (settings->priv->schema_name);
......@@ -1016,6 +1029,11 @@ g_settings_get_child (GSettings *settings,
*
* Creates a new #GSettings object with a given schema.
*
* Signals on the newly created #GSettings object will be dispatched
* via the thread-default #GMainContext in effect at the time of the
* call to g_settings_new(). The new #GSettings will hold a reference
* on the context. See g_main_context_push_thread_default().
*
* Since: 2.26
*/
GSettings *
......
......@@ -88,6 +88,7 @@ enum
struct _GSettingsBackendWatch
{
GMainContext *context;
GSettingsBackendChangedFunc changed;
GSettingsBackendPathChangedFunc path_changed;
GSettingsBackendKeysChangedFunc keys_changed;
......@@ -98,8 +99,22 @@ struct _GSettingsBackendWatch
GSettingsBackendWatch *next;
};
/*< private >
* g_settings_backend_watch:
* @backend: a #GSettingsBackend
* @context: a #GMainContext, or %NULL
* ...: callbacks...
* @user_data: the user_data for the callbacks
*
* Registers a new watch on a #GSettingsBackend.
*
* note: %NULL @context does not mean "default main context" but rather,
* "it is okay to dispatch in any context". If the default main context
* is specifically desired then it must be given.
**/
void
g_settings_backend_watch (GSettingsBackend *backend,
GMainContext *context,
GSettingsBackendChangedFunc changed,
GSettingsBackendPathChangedFunc path_changed,
GSettingsBackendKeysChangedFunc keys_changed,
......@@ -110,6 +125,11 @@ g_settings_backend_watch (GSettingsBackend *backend,
GSettingsBackendWatch *watch;
watch = g_slice_new (GSettingsBackendWatch);
/* don't need to ref the context here because the watch is
* only valid for the lifecycle of the attaching GSettings
* and it is already holding the context.
*/
watch->context = context;
watch->changed = changed;
watch->path_changed = path_changed;
watch->keys_changed = keys_changed;
......@@ -179,6 +199,115 @@ is_path (const gchar *path)
return TRUE;
}
static GMainContext *
g_settings_backend_get_active_context (void)
{
GMainContext *context;
GSource *source;
if ((source = g_main_current_source ()))
context = g_source_get_context (source);
else
{
context = g_main_context_get_thread_default ();
if (context == NULL)
context = g_main_context_default ();
}
return context;
}
typedef struct
{
void (*function) (GSettingsBackend *backend,
const gchar *name,
gpointer data1,
gpointer data2,
gpointer data3);
GSettingsBackend *backend;
gchar *name;
gpointer data1;
gpointer data2;
gpointer data3;
GDestroyNotify destroy_data1;
} GSettingsBackendClosure;
static gboolean
g_settings_backend_invoke_closure (gpointer user_data)
{
GSettingsBackendClosure *closure = user_data;
closure->function (closure->backend, closure->name,
closure->data1, closure->data2, closure->data3);
g_object_unref (closure->backend);
if (closure->destroy_data1)
closure->destroy_data1 (closure->data1);
g_free (closure->name);
/* make a donation to the magazine in this thread... */
g_slice_free (GSettingsBackendClosure, closure);
return FALSE;
}
static void
g_settings_backend_dispatch_signal (GSettingsBackend *backend,
GMainContext *context,
gpointer function,
const gchar *name,
gpointer data1,
GDestroyNotify destroy_data1,
gpointer data2,
gpointer data3)
{
GSettingsBackendClosure *closure;
GSource *source;
/* XXX we have a rather obnoxious race condition here.
*
* In the meantime of this call being dispatched to the other thread,
* the GSettings instance that is pointed to by the user_data may have
* been freed.
*
* There are two ways of handling this:
*
* 1) Ensure that the watch is still valid by the time it arrives in
* the destination thread (potentially expensive)
*
* 2) Do proper refcounting (requires changing the interface).
*/
closure = g_slice_new (GSettingsBackendClosure);
closure->backend = g_object_ref (backend);
closure->function = function;
/* we could make more effort to share this between all of the
* dispatches but it seems that it might be an overall loss in terms
* of performance/memory use and is definitely not worth the effort.
*/
closure->name = g_strdup (name);
/* ditto. */
closure->data1 = data1;
closure->destroy_data1 = destroy_data1;
closure->data2 = data2;
closure->data3 = data3;
source = g_idle_source_new ();
g_source_set_callback (source,
g_settings_backend_invoke_closure,
closure, NULL);
g_source_attach (source, context);
g_source_unref (source);
}
/**
* g_settings_backend_changed:
* @backend: a #GSettingsBackend implementation
......@@ -216,12 +345,20 @@ g_settings_backend_changed (GSettingsBackend *backend,
gpointer origin_tag)
{
GSettingsBackendWatch *watch;
GMainContext *context;
g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
g_return_if_fail (is_key (key));
context = g_settings_backend_get_active_context ();
for (watch = backend->priv->watches; watch; watch = watch->next)
watch->changed (backend, key, origin_tag, watch->user_data);
if (watch->context == context || watch->context == NULL)
watch->changed (backend, key, origin_tag, watch->user_data);
else
g_settings_backend_dispatch_signal (backend, watch->context,
watch->changed, key, origin_tag,
NULL, watch->user_data, NULL);
}
/**
......
......@@ -48,6 +48,7 @@ typedef void (*GSettingsBackendPathWritableChangedFunc) (GSettin
G_GNUC_INTERNAL
void g_settings_backend_watch (GSettingsBackend *backend,
GMainContext *context,
GSettingsBackendChangedFunc changed,
GSettingsBackendPathChangedFunc path_changed,
GSettingsBackendKeysChangedFunc keys_changed,
......@@ -97,4 +98,5 @@ void g_settings_backend_unsubscribe (GSettin
G_GNUC_INTERNAL
void g_settings_backend_subscribe (GSettingsBackend *backend,
const char *name);
#endif /* __G_SETTINGS_BACKEND_INTERNAL_H__ */
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