rt-thread的内核对象管理系统分析
rt-thread采用内核对象管理系统来访问和管理所有内核对象.首先来看看rt-thread的内核对象是如何定义的:
1 数据结构
1.1 对象控制块
在include/rtdef.h头文件中可以找到内核对象有结构定义:
/**
* Base structure of Kernel object
*/
struct rt_object
{
char name[RT_NAME_MAX];//名称
rt_uint8_t type;//内核对象类型
rt_uint8_t flag;//内核对象标志
#ifdef RT_USING_MODULE
void *module_id;//模块ID
#endif
rt_list_t list;//内核对象链表节点
};
typedef struct rt_object *rt_object_t;
这里需要注意地是,上述内核对象控制块包含了一rt_list_t类型的成员list,这个是一链表节点,便于将此内核对象加入到一链表中,其结构如下定义:
struct rt_list_node
{
struct rt_list_node *next; //指向下一节点
struct rt_list_node *prev; //指向前一节点
};
typedef struct rt_list_node rt_list_t;
另内核对象类型取值有如下类型:
/**
* The object type can be one of the follows with specific
* macros enabled:
* - Thread
* - Semaphore
* - Mutex
* - Event
* - MailBox
* - MessageQueue
* - MemHeap
* - MemPool
* - Device
* - Timer
* - Module
* - Unknown
* - Static
*/
enum rt_object_class_type
{
RT_Object_Class_Thread = 0, //线程
#ifdef RT_USING_SEMAPHORE
RT_Object_Class_Semaphore, //信号量
#endif
#ifdef RT_USING_MUTEX
RT_Object_Class_Mutex, //互斥锁
#endif
#ifdef RT_USING_EVENT
RT_Object_Class_Event, //事件
#endif
#ifdef RT_USING_MAILBOX
RT_Object_Class_MailBox, //邮箱
#endif
#ifdef RT_USING_MESSAGEQUEUE
RT_Object_Class_MessageQueue, //消息队列
#endif
#ifdef RT_USING_MEMHEAP
RT_Object_Class_MemHeap, //内存堆
#endif
#ifdef RT_USING_MEMPOOL
RT_Object_Class_MemPool, //内存池
#endif
#ifdef RT_USING_DEVICE
RT_Object_Class_Device, //设备驱动
#endif
RT_Object_Class_Timer, //时钟
#ifdef RT_USING_MODULE
RT_Object_Class_Module, //模块
#endif
RT_Object_Class_Unknown, //未知内核对象类型
RT_Object_Class_Static = 0x80 //rt-thread以此位标志是否为系统内核对象
};
需要注意的是,rt-thread将内核对象的type的最高位若为1,则表示此内核对象为系统内核对象,否则非系统内核对象.
1.2 内核对象容器
RTT使用内核对象容器来管理同一类型的内核对象,并将其放入同一链表中,便于访问.内核对象信息的结构如下定义:
/**
* The information of the kernel object
*/
struct rt_object_information
{
enum rt_object_class_type type; //内核对象类型
rt_list_t object_list; //内核对象链表
rt_size_t object_size; //内核对象所占的大小
};
1.3 内核对象管理系统
RTT中,每一类型的内核对象都会有一内核对象容器来包容,这个类型的内核对象容器实际上是用一链表(见1.2节所示的内核对象容器结构定义),这个链表将所有相同类型的内核对象链接起来.由于每一类型都对应着有一个这样的内核对象容器来管理,那么所有内核对象容器整体就叫做内核对象管理系统.
如下图示：
RTT中,内核对象管理系统是用一个rt_object_information数组来实现的,如下:
#define _OBJ_CONTAINER_LIST_INIT(c)\//内核对象容器的链表初始化,这里用一个宏来定义,链表的前一节点和后一节点在初始化时都指向本身所在地址
{&(rt_object_container[c].object_list), &(rt_object_container[c].object_list)}
//内核对象管理系统,这里用rt_object_information数组来实现
struct rt_object_information rt_object_container[RT_Object_Class_Unknown] =
{
/* initialize object container - thread */)},//线程对象信息
{RT_Object_Class_Thread, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Thread), sizeof(struct rt_thread#ifdef RT_USING_SEMAPHORE
/* initialize object container - semaphore *///信号量对象信息
{RT_Object_Class_Semaphore, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Semaphore), sizeof(struct rt_semaphore)},
#endif
#ifdef RT_USING_MUTEX
/* initialize object container - mutex *///互斥锁对象信息
{RT_Object_Class_Mutex, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Mutex), sizeof(struct rt_mutex)},
#endif
#ifdef RT_USING_EVENT
/* initialize object container - event *///事件对象信息
{RT_Object_Class_Event, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Event), sizeof(struct rt_event)},
#endif
#ifdef RT_USING_MAILBOX
/* initialize object container - mailbox *///邮箱对象信息
{RT_Object_Class_MailBox, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_MailBox), sizeof(struct rt_mailbox)},
#endif
#ifdef RT_USING_MESSAGEQUEUE
/* initialize object container - message queue *///消息队列对象信息
{RT_Object_Class_MessageQueue, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_MessageQueue), sizeof(struct rt_messagequeue)},
#endif
#ifdef RT_USING_MEMHEAP
/* initialize object container - memory heap *///内存堆对象信息
{RT_Object_Class_MemHeap, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_MemHeap), sizeof(struct rt_memheap)},
#endif
#ifdef RT_USING_MEMPOOL
/* initialize object container - memory pool *///内存池对象信息
{RT_Object_Class_MemPool, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_MemPool), sizeof(struct rt_mempool)},
#endif
#ifdef RT_USING_DEVICE
/* initialize object container - device *///设备驱动对象信息
{RT_Object_Class_Device, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Device), sizeof(struct rt_device)},
#endif
/* initialize object container - timer *///时钟对象信息
{RT_Object_Class_Timer, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Timer), sizeof(struct rt_timer)},
#ifdef RT_USING_MODULE
/* initialize object container - module *///模块对象信息
{RT_Object_Class_Module, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Module), sizeof(struct rt_module)},
#endif
};
2 内核对象接口
2.1 内核对象初始化
RTT提供静态和动态两种初始化接口,如下:
静态初始化是将一个已经存在的且占有内存空间的对象初始化,它的接口如下:
/**
* This function will initialize an object and add it to object system
* management.
*
* @param object the specified object to be initialized.
* @param type the object type.
* @param name the object name. In system, the object's name must be unique.
*/
void rt_object_init(struct rt_object *object,//指向已存在的对象指针
enum rt_object_class_type type, //对象的类型
const char *name) //对象的名字字符串
{
register rt_base_t temp;
struct rt_object_information *information; //对象容器
#ifdef RT_USING_MODULE //如果使用了模块,那么对象容器指向本线程所包含的对象窗口,否则指向全局对象管理系统中对应的容器
/* get module object information */
information = (rt_module_self() != RT_NULL) ?
&rt_module_self()->module_object[type] : &rt_object_container[type];
#else
/* get object information */
information = &rt_object_container[type];
#endif
/* initialize object's parameters */
/* set object type to static */
object->type = type | RT_Object_Class_Static;//设置系统对象标志
/* copy name */
rt_strncpy(object->name, name, RT_NAME_MAX);//给名字赋值
RT_OBJECT_HOOK_CALL(rt_object_attach_hook, (object));//使用钩子函数
/* lock interrupt */
temp = rt_hw_interrupt_disable();//关中断
/* insert object into information object list */
rt_list_insert_after(&(information->object_list), &(object->list));//将初始化的内核对象加入到对应容器中
/* unlock interrupt */
rt_hw_interrupt_enable(temp);//开中断
}
动态初始化是指对象原本并不存在,在不内存中,需要动态为其分配内存,其接口如下:
/**
* This function will allocate an object from object system
*
* @param type the type of object
* @param name the object name. In system, the object's name must be unique.
*
* @return object
*/
rt_object_t rt_object_allocate(enum rt_object_class_type type, const char *name)//动态初始化接口只需要传入名字和类型
{
struct rt_object *object;
register rt_base_t temp;
struct rt_object_information *information;//对象容器
RT_DEBUG_NOT_IN_INTERRUPT;
#ifdef RT_USING_MODULE//同上面那个接口一样,获取对象容器
/*
* get module object information,
* module object should be managed by kernel object container
*/
information = (rt_module_self() != RT_NULL && (type != RT_Object_Class_Module)) ?
&rt_module_self()->module_object[type] : &rt_object_container[type];
#else
/* get object information */
information = &rt_object_container[type];
#endif
object = (struct rt_object *)rt_malloc(information->object_size);//为对象动态分配内存空间
if (object == RT_NULL)
{
/* no memory can be allocated */
return RT_NULL;
}
/* initialize object's parameters */
/* set object type */
object->type = type;//设置类型
/* set object flag */
object->flag = 0;//设置标志为0
#ifdef RT_USING_MODULE
if (rt_module_self() != RT_NULL)
{
object->flag |= RT_OBJECT_FLAG_MODULE;//如果使用了模块功能,则将flag标志设置为模块标志
}
object->module_id = (void *)rt_module_self();//设置模块ID
#endif
/* copy name */
rt_strncpy(object->name, name, RT_NAME_MAX);//给名称赋值
RT_OBJECT_HOOK_CALL(rt_object_attach_hook, (object));//使用钩子函数
/* lock interrupt */
temp = rt_hw_interrupt_disable();//关中断
/* insert object into information object list */
rt_list_insert_after(&(information->object_list), &(object->list));//将此对象加入对应容器
/* unlock interrupt */
rt_hw_interrupt_enable(temp);//关中断
/* return object */
return object;
}
2.2 脱离或删除对象
如果对象是静态初始化的,那么对应的是脱离,如果是动态初始化的,则是删除.
脱离接口如下:
/**
* This function will detach a static object from object system,
* and the memory of static object is not freed.
*
* @param object the specified object to be detached.
*/
void rt_object_detach(rt_object_t object)
{
register rt_base_t temp;
/* object check */
RT_ASSERT(object != RT_NULL);
RT_OBJECT_HOOK_CALL(rt_object_detach_hook, (object));//使用钩子函数
/* lock interrupt */
temp = rt_hw_interrupt_disable();//关中断
/* remove from old list */
rt_list_remove(&(object->list));//从窗口中移除
/* unlock interrupt */
rt_hw_interrupt_enable(temp);//开中断
}
删除接口如下:
/**
* This function will delete an object and release object memory.
*
* @param object the specified object to be deleted.
*/
void rt_object_delete(rt_object_t object)
{
register rt_base_t temp;
/* object check */
RT_ASSERT(object != RT_NULL);
RT_ASSERT(!(object->type & RT_Object_Class_Static));//删除的对象必须是非系统对象
RT_OBJECT_HOOK_CALL(rt_object_detach_hook, (object));//使用钩子函数
/* lock interrupt */
temp = rt_hw_interrupt_disable();//关中断
/* remove from old list */
rt_list_remove(&(object->list));//从对应的容器中移除
/* unlock interrupt */
rt_hw_interrupt_enable(temp);//开中断
#if defined(RT_USING_MODULE) && defined(RT_USING_SLAB)//如果使用了模块功能且采用的是SLAB动态内存管理模式
if (object->flag & RT_OBJECT_FLAG_MODULE)
rt_module_free((rt_module_t)object->module_id, object);//释放模块ID所占空间
else
#endif
/* free the memory of object */
rt_free(object);//释放内核对象所占空间
}
其中rt_list_remove会自动找到对象的前一节点和后一节点,然后删除本身节点.
2.3 判断是否为系统内核对象
/**
* This function will judge the object is system object or not.
* Normally, the system object is a static object and the type
* of object set to RT_Object_Class_Static.
*
* @param object the specified object to be judged.
*
* @return RT_TRUE if a system object, RT_FALSE for others.
*/
rt_bool_t rt_object_is_systemobject(rt_object_t object)
{
/* object check */
RT_ASSERT(object != RT_NULL);
if (object->type & RT_Object_Class_Static)//RTT是通过内核对象的type的最高位是否为1来判断此对象是否为系统内核对象的
return RT_TRUE;
return RT_FALSE;
}
2.4查找内核对象
/**
* This function will find specified name object from object
* container.
*
* @param name the specified name of object.
* @param type the type of object
*
* @return the found object or RT_NULL if there is no this object
* in object container.
*
* @note this function shall not be invoked in interrupt status.
*/
rt_object_t rt_object_find(const char *name, rt_uint8_t type)
{
struct rt_object *object;
struct rt_list_node *node;
struct rt_object_information *information;
extern volatile rt_uint8_t rt_interrupt_nest;
/* parameter check *///输入系统检查
if ((name == RT_NULL) || (type > RT_Object_Class_Unknown))
return RT_NULL;
/* which is invoke in interrupt status */
if (rt_interrupt_nest != 0)//确保当前没有中断嵌套
RT_ASSERT(0);
/* enter critical */
rt_enter_critical();//进入临界区
/* try to find object */
information = &rt_object_container[type];//获取对应的对象容器
for (node = information->object_list.next;//开始通过名字来扫描内核对象
node != &(information->object_list);
node = node->next)
{
object = rt_list_entry(node, struct rt_object, list);//获取内核对象
if (rt_strncmp(object->name, name, RT_NAME_MAX) == 0)//判断名字是否相符
{
/* leave critical */
rt_exit_critical();//退出临界区
return object;
}
}
/* leave critical */
rt_exit_critical();//退出临界区
return RT_NULL;
}
3 内核对象系统初始化
/**
* @ingroup SystemInit
*
* This function will initialize system object management.
*
* @deprecated since 0.3.0, this function does not need to be invoked
* in the system initialization.
*/
void rt_system_object_init(void)
{
}
从源代码可以看出,自从0.3.0以后,RTT就已经没有必须再使用此接口来对内核对象初始化了,因此,此函数是空的,但在系统初始化时还会保留调用些函数.
至此,RTT的内核对象系统源码分析已完!