H中的Hashtable插入/搜索

你好，我的哈希表有问题，它实现如下：

#define HT_SIZE 10 
typedef struct _list_t_ {
    char key[20];
    char string[20];
    char prevValue[20];
    struct _list_t_ *next;
} list_t;

typedef struct _hash_table_t_ {
    int size;       /* the size of the table */
    list_t ***table; /* first */
    sem_t lock;
} hash_table_t;

我有一个带有3个指针的链表，因为我想要一个带有几个分区（分片）的哈希表，这是我的Hash表的初始化：

hash_table_t *create_hash_table(int NUM_SERVER_THREADS, int num_shards){
    hash_table_t *new_table;    
    int j,i;
    if (HT_SIZE<1) return NULL; /* invalid size for table */
    /* Attempt to allocate memory for the hashtable structure */
    new_table = (hash_table_t*)malloc(sizeof(hash_table_t)*HT_SIZE);
    /* Attempt to allocate memory for the table itself */
    new_table->table = (list_t ***)calloc(1,sizeof(list_t **));
    /* Initialize the elements of the table */
    for(j=0; j<num_shards; j++){
        new_table->table[j] = (list_t **)calloc(1,sizeof(list_t *));
        for(i=0; i<HT_SIZE; i++){
            new_table->table[j][i] = (list_t *)calloc(1,sizeof(list_t ));
        }
    }
    /* Set the table's size */
    new_table->size = HT_SIZE;
    sem_init(&new_table->lock, 0, 1);
    return new_table;
}

这是我在哈希表中搜索的搜索功能

list_t *lookup_string(hash_table_t *hashtable, char *key, int shardId){

    list_t *list ;

    int hashval = hash(key);
    /* Go to the correct list based on the hash value and see if key is
     * in the list.  If it is, return return a pointer to the list element.
     * If it isn't, the item isn't in the table, so return NULL.
     */
    sem_wait(&hashtable->lock);

    for(list = hashtable->table[shardId][hashval]; list != NULL; list =list->next) {
        if (strcmp(key, list->key) == 0){
                sem_post(&hashtable->lock);
                return list;
        }
    }
    sem_post(&hashtable->lock);

    return NULL;
}

我的插入功能：

char *add_string(hash_table_t *hashtable, char *str,char *key, int shardId){
    list_t *new_list;
    list_t *current_list;
    unsigned int hashval = hash(key);
    /*printf("|%d|%d|%s|\n",hashval,shardId,key);*/
    /* Lock for concurrency */
    sem_wait(&hashtable->lock);
    /* Attempt to allocate memory for list */
    new_list = (list_t*)malloc(sizeof(list_t));

    /* Does item already exist? */
    sem_post(&hashtable->lock);
    current_list = lookup_string(hashtable, key,shardId);
    sem_wait(&hashtable->lock);
        /* item already exists, don't insert it again. */
    if (current_list != NULL){
        strcpy(new_list->prevValue,current_list->string);
        strcpy(new_list->string,str);
        strcpy(new_list->key,key);
        new_list->next = hashtable->table[shardId][hashval];
        hashtable->table[shardId][hashval] = new_list;
        sem_post(&hashtable->lock);
        return new_list->prevValue;
    }
    /* Insert into list */
    strcpy(new_list->string,str);
    strcpy(new_list->key,key);
    new_list->next = hashtable->table[shardId][hashval];
    hashtable->table[shardId][hashval] = new_list;
    /* Unlock */
    sem_post(&hashtable->lock);
    return new_list->prevValue;
}

我的主类通过执行插入/读取/删除哈希表的元素来运行一些测试问题是当我有超过4个分区/分片时，测试在第一个读取元素停止，说它返回了错误的值NULL搜索功能，当它小于4时，它运行得很好，并通过所有测试 .

如果你想看一下，你可以在这里看到我的main.c：

http://hostcode.sourceforge.net/view/1105

我完整的哈希表代码：

http://hostcode.sourceforge.net/view/1103

以及执行哈希表代码的其他函数：

.c文件http://hostcode.sourceforge.net/view/1104

.h文件http://hostcode.sourceforge.net/view/1106

谢谢你的时间，我感谢你能给我的任何帮助这是一个我正在努力解决的大学重要项目，我被困在这里2天 .