RT-Thread源码阅读(3)——内核对象管理
_object_container对象容器数组
在RT-Thread操作系统中，_object_container数组的作用是按类型分类管理内核对象，提供高效的类型检查、资源管理和统计功能
struct rt_list_node
{struct rt_list_node *next; /**< point to next node. */struct rt_list_node *prev; /**< point to prev node. */
};
typedef struct rt_list_node rt_list_t; /**< Type for lists. */struct rt_object_information
{enum rt_object_class_type type; /**< object class type */rt_list_t object_list; /**< object list */rt_size_t object_size; /**< object size */
};#define _OBJ_CONTAINER_LIST_INIT(c) \{&(_object_container[c].object_list), &(_object_container[c].object_list)}static struct rt_object_information _object_container[RT_Object_Info_Unknown] =
{/* initialize object container - thread */{RT_Object_Class_Thread, _OBJ_CONTAINER_LIST_INIT(RT_Object_Info_Thread), sizeof(struct rt_thread)},/* initialize object container - semaphore */{RT_Object_Class_Semaphore, _OBJ_CONTAINER_LIST_INIT(RT_Object_Info_Semaphore), sizeof(struct rt_semaphore)},// ......
}
从源码可以看出，_object_container包含了所有对象，如thread、sem等
_OBJ_CONTAINER_LIST_INIT可能比较难理解，里面有两个一模一样的&(_object_container[c].object_list)，乍一看rt_object_information结构体也才3个元素，这里宏展开后一共都有4个元素了？
其实不然，_OBJ_CONTAINER_LIST_INIT用了花括号，只代表一个元素rt_list_t object_list，花括号里的值代表着next 和 prev
至于为什么是两个一模一样的值，看过rt_list_init函数就理解了，这也和这个宏的名字对上了，即初始化
// 链表初始化 即自己指向自己
rt_inline void rt_list_init(rt_list_t *l)
{l->next = l->prev = l;
}
rt_object_allocate（用于动态创建对象）
rt_object_allocate为新创建的对象申请句柄内存，并将其加入到链表中
以下是动态创建线程的接口代码：
rt_thread_t rt_thread_create(const char *name, void (*entry)(void *parameter), void *parameter, rt_uint32_t stack_size,rt_uint8_t priority, rt_uint32_t tick)
{struct rt_thread *thread;void *stack_start;thread = (struct rt_thread *)rt_object_allocate(RT_Object_Class_Thread, name);stack_start = (void *)RT_KERNEL_MALLOC(stack_size);_thread_init(thread, name, entry, parameter, stack_start, stack_size, priority, tick);return thread;
}rt_object_t rt_object_allocate(enum rt_object_class_type type, const char *name)
{struct rt_object *object;rt_base_t level;struct rt_object_information *information;// 获取对应类型对象管理结构体information = rt_object_get_information(type);// 为句柄申请空间object = (struct rt_object *)RT_KERNEL_MALLOC(information->object_size);rt_memset(object, 0x0, information->object_size);object->type = type;object->flag = 0;rt_strncpy(object->name, name, RT_NAME_MAX);// 将新创建的链表加入到对象管理结构体的链表中rt_list_insert_after(&(information->object_list), &(object->list));return object;
}
list_find_init（用于遍历对象）
在FinSH命令行插件中，有查看对象状态的功能，如list_thread
其示意代码如下：
typedef struct
{rt_list_t *list;rt_list_t **array;rt_uint8_t type;int nr; // 最大个数int nr_out; // 实际个数
} list_get_next_t;static void list_find_init(list_get_next_t *p, rt_uint8_t type, rt_list_t **array, int nr)
{struct rt_object_information *info;rt_list_t *list;// 返回对应的对象管理结构体info = rt_object_get_information((enum rt_object_class_type)type);// 找到最关键的链表list = &info->object_list;p->list = list;p->type = type;p->array = array;p->nr = nr;p->nr_out = 0;
}long list_thread(void)
{list_get_next_t find_arg;rt_list_t *obj_list[LIST_FIND_OBJ_NR];rt_list_t *next = (rt_list_t *)RT_NULL;list_find_init(&find_arg, RT_Object_Class_Thread, obj_list, sizeof(obj_list) / sizeof(obj_list[0]));do{// 这里给obj_list数组赋值，里面存着每个对象的链表// 这里一次最多获取LIST_FIND_OBJ_NR个对象next = list_get_next(next, &find_arg);{int i;// 循环打印对象信息for (i = 0; i < find_arg.nr_out; i++){struct rt_object *obj;struct rt_thread *thread;// 通过结构体中的元素找到结构体本身，第一章中有详细讲解rt_list_entryobj = rt_list_entry(obj_list[i], struct rt_object, list);thread = (struct rt_thread *)obj;// 打印相关信息}}} while (next != (rt_list_t *)RT_NULL);return 0;
}
rt_object 结构体
基础的结构体，所有内核对象结构体的开头都会定义struct rt_object parent;
但是不知道为什么rt_thread结构体开头把rt_object 展开了，但是效果和offset都是一致的
/*** Base structure of Kernel object*/
struct rt_object
{char name[RT_NAME_MAX]; /**< name of kernel object */rt_uint8_t type; /**< type of kernel object */rt_uint8_t flag; /**< flag of kernel object */rt_list_t list; /**< list node of kernel object */
};
typedef struct rt_object *rt_object_t; /**< Type for kernel objects. */