内核红黑树使用范例

　　内核中的红黑树只是提供了一个管理机制，并没有提供具体的使用接口。需要使用者根据自己的使用环境去定义和实现自己的关键字（char，uchar, int, uint等类型）操作。这样可以更加灵活。

　　像内核中的链表，hash表的代码都是这种思想。

struct mytype
{  
    int num;  

    struct rb_node my_node;  
};  

struct mytype *my_find(struct rb_root *root, int num)  
{  
    struct rb_node *node = root->rb_node;  

    while (node) {  
        struct mytype *data = rb_entry(node, struct mytype, my_node);

        if (num < data->num)  
            node = node->rb_left;  
        else if (num > data->num)  
            node = node->rb_right;  
        else  
            return data;  
    }  

    return NULL;  
}  


int my_insert(struct rb_root *root,  struct mytype *data)  
{  
    struct rb_node  *parent = NULL;
    struct rb_node **tmp = &(root->rb_node); 

    /* Figure out where to put new node */  
    while (*tmp) {  
        struct mytype *this = rb_entry(*tmp, struct mytype, my_node);  

        parent = *tmp;  
        if (data->num < this->num)  
            tmp = &((*tmp)->rb_left);  
        else if (data->num > this->num)  
            tmp = &((*tmp)->rb_right);  
        else   
            return -1;  
    }  

    /* Add new node and rebalance tree. */  
    rb_link_node(&data->my_node, parent, tmp);  
    rb_insert_color(&data->my_node, root);  

    return 0;  
}  


void my_delete(struct rb_root *root, int num)  
{  
    struct mytype *data = my_find(root, num);  
    if(data != NULL)
    {
        rb_erase(&data->my_node, root);  
        free(data);  
    }
}  

void my_destory(struct rb_root *tree)
{
    struct rb_node *node;  

    for(node = rb_first(tree); node; node = rb_next(node))
    {
        my_delete(tree, rb_entry(node, struct mytype, my_node)->num);
    }
}

void my_printf(struct rb_root *tree)  
{  
    struct rb_node *node;  

    for(node = rb_first(tree); node; node = rb_next(node))
    {
        printf("%d ", rb_entry(node, struct mytype, my_node)->num);  
    }

    printf("\n");  
}  


#define RBTREE_MAX_NUM 10

int main(int argc, char *argv[])  
{  
    struct mytype *tmp = NULL;
    struct rb_root mytree = RB_ROOT; 
    
    srand((unsigned int)time(NULL));

    unsigned int i = 0;
    for(i = 0; i < RBTREE_MAX_NUM; ++i)
    {
        tmp = malloc(sizeof(struct mytype)); 
        if(tmp == NULL)
        {
            perror("Allocate dynamic memory");
            exit(-1);
        }
        
        tmp->num = rand()%100;
        
        printf("%d ", tmp->num);
        
        int ret = my_insert(&mytree, tmp);  
        if (ret < 0) 
        {  
            fprintf(stderr, "The %d already exists\n", tmp->num);  
            free(tmp);  
        }
    }
    
    printf("\n");

    my_printf(&mytree); 
    
    char buf[10];
    
    while(1)
    {
        printf("\n****************************************");
        printf("\n* +number to insert :");
        printf("\n* -number to delete :");
        printf("\n*       q to quit   :");
        printf("\n****************************************\n");
        
        fgets(buf, sizeof(buf), stdin);

        if(buf[0] == 'q')
        {
            break;
        }
        else if(buf[0] == '+')
        {
            tmp = malloc(sizeof(struct mytype)); 
            if(tmp == NULL)
            {
                perror("Allocate dynamic memory");
                continue;
            }
            
            tmp->num = atoi(&buf[1]);
            
            int ret = my_insert(&mytree, tmp);  
            if (ret < 0) 
            {  
                fprintf(stderr, "The %d already exists\n", tmp->num);  
                free(tmp);  
            }
        }
        else if(buf[0] == '-')
        {
            my_delete(&mytree, atoi(&buf[1])); 
        }
        else
        {
            continue;
        }
        
        my_printf(&mytree); 

    }

    my_destory(&mytree);

    return 0;  
}