关于线程对象的继承问题

发布于 2019-06-10 21:26:34 浏览：1402 订阅该版

根据官方书籍所述，内存池、thread、ipc、定时器、设备这几个对象，都是继承于object对象而来，为什么在定义数据结构的时候，thread对象要将object成员变量重写，而不像timer对象那样，直接对object对象继承呢？这其中是有什么原因吗？
object对象：
```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 */

#ifdef RT_USING_MODULE
    void      *module_id;                               /**< id of application module */
#endif
    rt_list_t  list;                                    /**< list node of kernel object */
};
typedef struct rt_object *rt_object_t;                  /**< Type for kernel objects. */```

thread对象：

```struct rt_thread
{
    /* rt object */
    char        name[RT_NAME_MAX];                      /**< the name of thread */
    rt_uint8_t  type;                                   /**< type of object */
    rt_uint8_t  flags;                                  /**< thread's flags */

#ifdef RT_USING_MODULE
    void       *module_id;                              /**< id of application module */
#endif

rt_list_t   list;                                   /**< the object list */
    rt_list_t   tlist;                                  /**< the thread list */

/* stack point and entry */
    void       *sp;                                     /**< stack point */
    void       *entry;                                  /**< entry */
    void       *parameter;                              /**< parameter */
    void       *stack_addr;                             /**< stack address */
    rt_uint32_t stack_size;                             /**< stack size */

/* error code */
    rt_err_t    error;                                  /**< error code */

rt_uint8_t  stat;                                   /**< thread status */

/* priority */
    rt_uint8_t  current_priority;                       /**< current priority */
    rt_uint8_t  init_priority;                          /**< initialized priority */
#if RT_THREAD_PRIORITY_MAX > 32
    rt_uint8_t  number;
    rt_uint8_t  high_mask;
#endif
    rt_uint32_t number_mask;

#if defined(RT_USING_EVENT)
    /* thread event */
    rt_uint32_t event_set;
    rt_uint8_t  event_info;
#endif

#if defined(RT_USING_SIGNALS)
    rt_sigset_t     sig_pending;                        /**< the pending signals */
    rt_sigset_t     sig_mask;                           /**< the mask bits of signal */

void            *sig_ret;                           /**< the return stack pointer from signal */
    rt_sighandler_t *sig_vectors;                       /**< vectors of signal handler */
    void            *si_list;                           /**< the signal infor list */
#endif

rt_ubase_t  init_tick;                              /**< thread's initialized tick */
    rt_ubase_t  remaining_tick;                         /**< remaining tick */

struct rt_timer thread_timer;                       /**< built-in thread timer */

void (*cleanup)(struct rt_thread *tid);             /**< cleanup function when thread exit */

rt_uint32_t user_data;                              /**< private user data beyond this thread */
};
typedef struct rt_thread *rt_thread_t;```

timer对象：
```struct rt_timer
{
    struct rt_object parent;                            /**< inherit from rt_object */

rt_list_t        row[RT_TIMER_SKIP_LIST_LEVEL];

void (*timeout_func)(void *parameter);              /**< timeout function */
    void            *parameter;                         /**< timeout function's parameter */

rt_tick_t        init_tick;                         /**< timer timeout tick */
    rt_tick_t        timeout_tick;                      /**< timeout tick */
};
typedef struct rt_timer *rt_timer_t;
```