GLib-GObject-WARNING **: cannot register existing type...

最新推荐文章于 2025-04-09 08:33:06 发布

原创最新推荐文章于 2025-04-09 08:33:06 发布 · 8k 阅读

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#webkit #library #initialization #web #gtk #string

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本文探讨了在 Linux 下使用依赖于 libglib-2.0 和 libgobject-2.0 的共享库时遇到的问题：重复加载库导致无法注册已存在的类型 `WebKitWebView`。文章深入分析了错误发生的原因，并探讨了 g_type_register_static_simple 宏的实现细节。

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Problem:
When using dl functions under linux, dynamic load shared library,which depends on libglib-2.0 & libgobject-2.0, and close it, everything is ok now; But after dlopen the library again, error happened, just as follows:

(app:15420): GLib-GObject-WARNING **: cannot register existing type `WebKitWebView'
(app:15420): GLib-CRITICAL **: g_once_init_leave: assertion `initialization_value != 0' failed.

Solution:

where “cannot register existing type***” happened?
@ gtype.c
static gboolean check_type_name_I (const gchar * type_name) {....}
---> g_type_from_name(type_name))
error occured if type_name already exists in static_type_node_ht, but glib don’t give any method to unregister the typename;

the dependency relation is like this:
check_type_name_I <--- g_type_register_static <---- g_type_register_static_simple

@gtype.h
g_type_register_static_simple is defined in gtype.h
#define G_DEFINE_TYPE(TN, t_n, T_P)             G_DEFINE_TYPE_EXTENDED (TN,
t_n, T_P, 0,
{})

#define G_DEFINE_TYPE_EXTENDED(TN, t_n, T_P, _f_, _C_)
_G_DEFINE_TYPE_EXTENDED_BEGIN (TN, t_n, T_P, _f_) {_C_;}
_G_DEFINE_TYPE_EXTENDED_END()

G_DEFINE_TYPE_EXTENDED

@ webkit_web_view.cpp

G_DEFINE_TYPE_EXTENDED
(WebKitWebView,
webkit_web_view,
GTK_TYPE_CONTAINER,
0,
{});

the macro above generate codes:
GType webkit_web_view_get_type
(void)
{

static volatile gsize g_define_type_id__volatile =
0;

if (g_once_init_enter(&g_define_type_id__volatile))

{

   GType g_define_type_id = g_type_register_static_simple
   (GTK_TYPE_CONTAINER,g_intern_static_string("WebKitWebView"),sizeof(WebKitWebViewClass),
   (GClassInitFunc)webkit_web_view_class_intern_init, sizeof(WebKitWebView),
   (GInstanceInitFunc)webkit_web_view_init,(GTypeFlags) 0);

   g_once_init_leave (&g_define_type_id__volatile,g_define_type_id);
   return g_define_type_id__volatile;
}

WEBKIT_TYPE_WEB_VIEW == webkit_web_view_get_type

when calling webkit_web_view_new , WEBKIT_TYPE_WEB_VIEW is called, that’s why the error occures.

Until now, the problem has been located, but why the shared library was modify (the type info registered exists fater reload), dl mode is not COW ? i try to load all dependency library to make a copy, still the same....