#include "k-userhash.h"
#include <linux/slab.h>
#include <asm/errno.h>
#include <linux/kthread.h>

/*声明读写锁 */
DEFINE_RWLOCK(g_obj_lock);

/*定义大小为HASH_SIZE的hashtable */
struct list_head hash_array[HASH_SIZE];

/*init hashtable */
void init_hashMap(void)
{
    int i;
    for(i = 0; i < HASH_SIZE; i++)
        INIT_LIST_HEAD(&hash_array[i]);
}

/*获取hashtable位置索引 */
int get_hash_index(uint32_t ip)
{
  int val = ip % HASH_SIZE;
  return val;
}


/* search node */
USERINFO *search_user(uint32_t ip)
{
    int index;
    struct list_head *pos;
    USERINFO *pNode;

    index = get_hash_index(ip);

    /*查找用户IP */
    read_lock(&g_obj_lock);
    list_for_each(pos, &hash_array[index])
    {
      
        /* list_entry - get the struct for this entry
        * @ptr:	the &struct list_head pointer.
        * @type:the type of the struct this is embedded in.
        * @member:	the name of the list_head within the struct. */
        pNode = list_entry(pos, USERINFO, hnode);
        if(pNode != NULL)
        printk("user ip:%ld user id:%d\n", pNode->user_ip, pNode->user_id);
        return pNode;
    }
    read_unlock(&g_obj_lock);

    return NULL;
}


/*add user */
int add_user(uint32_t ip, int id)
{
    int index;
    USERINFO *pNode = NULL;

    /*获取hashtable位置索引 */
    index = get_hash_index(ip);
    pNode = search_user(ip);   

    if( NULL == pNode)
    {
        /*分配存储空间——GFP_KERNEL内核内存的正常分配. 可能睡眠. */
        pNode = (USERINFO *)kmalloc(sizeof(USERINFO), GFP_KERNEL);
        if (pNode == NULL)
        {
            return ENOMEM;
        }
        pNode->user_ip = ip;
        list_add_tail(&pNode->hnode,&hash_array[index]);
    }

    printk("IP ALEADY EXISTED\n");
    pNode->user_id = id;
    return 0;
}


/*delete a node */
void del_user(uint32_t ip)
{
    int index;
    struct list_head *pos, *n;
    USERINFO *pNode;
    index = get_hash_index(ip);

    /*判断hashtable中该单元是否为空 */
    if( list_empty(&hash_array[index]))
    {
        printk("node is NULL\n");
        return;
    }
    
    /*查找用户ip */
    write_lock(&g_obj_lock);
    list_for_each_safe(pos, n, &hash_array[index])
    {
        pNode = list_entry(pos, USERINFO, hnode);
        if(pNode->user_ip == ip)
        list_del(&pNode->hnode);
        kfree(pNode);
    }
    write_unlock(&g_obj_lock);

    return;
}

/*delete all node */
void free_all_user(void)
{
    int i;
    struct list_head *pos, *n;
    USERINFO *pNode;

    /*判断hashtable单元是否为NULL */
    for(i = 0; i < HASH_SIZE; i++)
    {
        if(list_empty(&hash_array[i]))
            continue;
        write_lock(&g_obj_lock);
        list_for_each_safe(pos, n, &hash_array[i])
        {
            pNode = list_entry(pos, USERINFO, hnode);
            list_del(&pNode->hnode);
            kfree(pNode);
        }
        write_unlock(&g_obj_lock);
    }

}

/*printf all nodes */
void printk_all_user(void)
{
    int i;
    struct list_head *pos, *n;
    USERINFO * pNode;

    for(i = 0; i < HASH_SIZE; i++)
        continue;
    read_lock(&g_obj_lock);
    list_for_each_safe(pos, n, &hash_array[i])
    {
        pNode = list_entry(pos, USERINFO, hnode);
        printk("user ip:%d user id:%d\n", pNode->user_ip, pNode->user_id);
    }
    read_unlock(&g_obj_lock);

}