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Happy coding
type.h
os
posted @ 2013年8月10日 17:13
in GObject
, 1052 阅读
Read the source code!
看再多的文档，最后都要回归到code上面来。
Gtype.h:
/* Basic Type Macros */ #define G_TYPE_FUNDAMENTAL(type) (g_type_fundamental (type)) #define G_TYPE_FUNDAMENTAL_MAX (255 << G_TYPE_FUNDAMENTAL_SHIFT) //1020 #define G_TYPE_INVALID G_TYPE_MAKE_FUNDAMENTAL (0) //0 #define G_TYPE_NONE G_TYPE_MAKE_FUNDAMENTAL (1) //4 #define G_TYPE_INTERFACE G_TYPE_MAKE_FUNDAMENTAL (2) //8 #define G_TYPE_CHAR G_TYPE_MAKE_FUNDAMENTAL (3) //12 #define G_TYPE_UCHAR G_TYPE_MAKE_FUNDAMENTAL (4) //16 #define G_TYPE_BOOLEAN G_TYPE_MAKE_FUNDAMENTAL (5) //20 #define G_TYPE_INT G_TYPE_MAKE_FUNDAMENTAL (6) //24 #define G_TYPE_UINT G_TYPE_MAKE_FUNDAMENTAL (7) #define G_TYPE_LONG G_TYPE_MAKE_FUNDAMENTAL (8) #define G_TYPE_ULONG G_TYPE_MAKE_FUNDAMENTAL (9) #define G_TYPE_INT64 G_TYPE_MAKE_FUNDAMENTAL (10) #define G_TYPE_UINT64 G_TYPE_MAKE_FUNDAMENTAL (11) #define G_TYPE_ENUM G_TYPE_MAKE_FUNDAMENTAL (12) #define G_TYPE_FLAGS G_TYPE_MAKE_FUNDAMENTAL (13) #define G_TYPE_FLOAT G_TYPE_MAKE_FUNDAMENTAL (14) #define G_TYPE_DOUBLE G_TYPE_MAKE_FUNDAMENTAL (15) #define G_TYPE_STRING G_TYPE_MAKE_FUNDAMENTAL (16) #define G_TYPE_POINTER G_TYPE_MAKE_FUNDAMENTAL (17) #define G_TYPE_BOXED G_TYPE_MAKE_FUNDAMENTAL (18) #define G_TYPE_PARAM G_TYPE_MAKE_FUNDAMENTAL (19) #define G_TYPE_OBJECT G_TYPE_MAKE_FUNDAMENTAL (20) #define G_TYPE_VARIANT G_TYPE_MAKE_FUNDAMENTAL (21) //84
有个疑问：为什么要shift移位?：
#define G_TYPE_FUNDAMENTAL_SHIFT (2)
if (!pnode) /* offset fundamental types */
{
node = G_STRUCT_MEMBER_P (node, SIZEOF_FUNDAMENTAL_INFO);
static_fundamental_type_nodes[ftype >> G_TYPE_FUNDAMENTAL_SHIFT] = node;
type = ftype;
}
static inline TypeNode*
lookup_type_node_I (register GType utype)
{
if (utype > G_TYPE_FUNDAMENTAL_MAX)
return (TypeNode*) (utype & ~TYPE_ID_MASK);
else
return static_fundamental_type_nodes[utype >> G_TYPE_FUNDAMENTAL_SHIFT];
}
这种左移，右移的移位操作，本身效率是高，但是为什么要这样做？ |
类函数何时用？
GType boilerplate:
模板文件，这些宏，在后面用户自定义GObject时非常有用，
要理解他们，用好他们；
Gtype.c:
/* --- structures --- */
struct _TypeNode
{
guint volatile ref_count;
GTypePlugin *plugin;
guint n_children; /* writable with lock */ //子辈的个数
guint n_supers : 8; //父辈的个数
guint n_prerequisites : 9;
guint is_classed : 1;
guint is_instantiatable : 1;
guint mutatable_check_cache : 1; /* combines some common path checks */
GType *children; /* writable with lock */ //指针数组，用来保持孩子的信息：pnode->children[i] = type; pnode->children = g_renew (GType, pnode->children, pnode->n_children);
TypeData * volatile data;
GQuark qname;
GData *global_gdata;
union {
GAtomicArray iface_entries; /* for !iface types */
GAtomicArray offsets;
} _prot;
GType *prerequisites;
GType supers[1]; /* flexible array */ //直接用memory copy进行增长
};
#define NODE_TYPE(node) (node->supers[0]) //自己
#define NODE_PARENT_TYPE(node) (node->supers[1]) //父亲
#define NODE_FUNDAMENTAL_TYPE(node) (node->supers[node->n_supers]) //最顶层的父亲，就是基本类型
/* --- type nodes --- */
static GHashTable *static_type_nodes_ht = NULL;
static TypeNode *static_fundamental_type_nodes[(G_TYPE_FUNDAMENTAL_MAX >> G_TYPE_FUNDAMENTAL_SHIFT) + 1] = { NULL, }; //全局的指针数组，用来保存基本类型，256个
static GType static_fundamental_next = G_TYPE_RESERVED_USER_FIRST;
？为什么需要一个hash table和一个全局的指针数组来保存Node节点呢？
数组查找快？
下面这个函数，同时操作上面的hash table和全局数组static_fundamental_type_nodes[]
static TypeNode*
type_node_any_new_W (TypeNode *pnode,
GType ftype,
const gchar *name,
GTypePlugin *plugin,
GTypeFundamentalFlags type_flags)
{
guint n_supers;
GType type;
TypeNode *node;
guint i, node_size = 0;
n_supers = pnode ? pnode->n_supers + 1 : 0; //如果有父类，则父类加1，否则父类为0
//如果没有父类，则按照基础类型大小
if (!pnode)
node_size += SIZEOF_FUNDAMENTAL_INFO; /* fundamental type info */
node_size += SIZEOF_BASE_TYPE_NODE (); /* TypeNode structure */
node_size += (sizeof (GType) * (1 + n_supers + 1)); /* self + ancestors + (0) for ->supers[] */
//给新节点分配内存
node = g_malloc0 (node_size);
//如果没有父节点，则直接保存在基础类型static_fundamental_type_nodes数组中
if (!pnode) /* offset fundamental types */
{
node = G_STRUCT_MEMBER_P (node, SIZEOF_FUNDAMENTAL_INFO);
static_fundamental_type_nodes[ftype >> G_TYPE_FUNDAMENTAL_SHIFT] = node;
type = ftype;
}
else
type = (GType) node; //如果有父节点，则新分配的节点作为当前节点
g_assert ((type & TYPE_ID_MASK) == 0);
node->n_supers = n_supers; //记录有几个父节点
if (!pnode)
{ //如果没有父节点
node->supers[0] = type; //第一个节点就是，自己
node->supers[1] = 0;
node->is_classed = (type_flags & G_TYPE_FLAG_CLASSED) != 0;
node->is_instantiatable = (type_flags & G_TYPE_FLAG_INSTANTIATABLE) != 0;
if (NODE_IS_IFACE (node))
{
IFACE_NODE_N_PREREQUISITES (node) = 0;
IFACE_NODE_PREREQUISITES (node) = NULL;
}
else
_g_atomic_array_init (CLASSED_NODE_IFACES_ENTRIES (node));
}
else
{ //如果有父节点
node->supers[0] = type; //第一个节点就是自己
//node->supers+1，指针后移动
//把父节点的所有数据，都复制一份给当前节点，作为当前节点的父类信息
memcpy (node->supers + 1, pnode->supers, sizeof (GType) * (1 + pnode->n_supers + 1));
node->is_classed = pnode->is_classed;
node->is_instantiatable = pnode->is_instantiatable;
if (NODE_IS_IFACE (node))
{
IFACE_NODE_N_PREREQUISITES (node) = 0;
IFACE_NODE_PREREQUISITES (node) = NULL;
}
else
{
guint j;
IFaceEntries *entries;
entries = _g_atomic_array_copy (CLASSED_NODE_IFACES_ENTRIES (pnode),
IFACE_ENTRIES_HEADER_SIZE,
0);
if (entries)
{
for (j = 0; j < IFACE_ENTRIES_N_ENTRIES (entries); j++)
{
entries->entry[j].vtable = NULL;
entries->entry[j].init_state = UNINITIALIZED;
}
_g_atomic_array_update (CLASSED_NODE_IFACES_ENTRIES (node),
entries);
}
}
//再和父类建立好关系
i = pnode->n_children++;
pnode->children = g_renew (GType, pnode->children, pnode->n_children);
pnode->children[i] = type;
}
TRACE(GOBJECT_TYPE_NEW(name, node->supers[1], type));
node->plugin = plugin;
node->n_children = 0;
node->children = NULL;
node->data = NULL;
node->qname = g_quark_from_string (name);
node->global_gdata = NULL;
//同时压入hash table中
g_hash_table_insert (static_type_nodes_ht,
GUINT_TO_POINTER (node->qname),
(gpointer) type);
return node;
}
上面提到的那个静态全局数组：TypeNode * static_fundamental_type_nodes[256];
|
TypeNode * |
TypeNode * |
TypeNode * |
…… |
TypeNode * |
保存的基础节点，即：没有父类的节点类型：同时，这些type也是可以做父亲的类型
| `Void | `GInterface | `GTypePlugin | `gchar | `guchar | `gboolean | `gint | `guint | `glong | `gulong | `gint64 | `guint64 | `GEnum | `GFlags | `gfloat | `gdouble | `gchararray | `gpointer | `GType | `GBoxed | `GValueArray | `GParam | `GParamVariant | `GObject | `GVariant
下面是个内联函数，可以取代宏，有编译器直接展开，效率高；
同时，也可以检查参数的有效性；
static inline TypeNode*
lookup_type_node_I (register GType utype)
{
if (utype > G_TYPE_FUNDAMENTAL_MAX)
return (TypeNode*) (utype & ~TYPE_ID_MASK);
else
return static_fundamental_type_nodes[utype >> G_TYPE_FUNDAMENTAL_SHIFT];
}
数组的直接访问，效率是非常高的。
另外一个Hash Table: GHashTable *static_type_nodes_ht = NULL;
只有一个函数进行了调用：
GType
g_type_from_name (const gchar *name)
{
GType type = 0;
GQuark quark;
g_return_val_if_fail (name != NULL, 0);
quark = g_quark_try_string (name);
if (quark)
{
G_READ_LOCK (&type_rw_lock);
type = (GType) g_hash_table_lookup (static_type_nodes_ht, GUINT_TO_POINTER (quark));
G_READ_UNLOCK (&type_rw_lock);
}
return type;
}
根据“名字”来查询，Hash Table的效率要高；
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