阅读memcacheq的hashtable实现的时候,发现在创建一个存储链表的数组时,使用void **的方法建立数组,即数组里存放的是链表指针,这样在删除元素时,只需要用一个指针的指针(保存当前链表实体的地址),这样删除就方便多了
struct entry { void *k, *v; unsigned int h; struct entry *next; }; struct hashtable { unsigned int tablelength; struct entry **table; unsigned int entrycount; unsigned int loadlimit; unsigned int primeindex; unsigned int (*hashfn) (void *k); int (*eqfn) (void *k1, void *k2); };
void * hashtable_remove(struct hashtable *h, void *k) { /* TODO: consider compacting the table when the load factor drops enough, * or provide a 'compact' method. */ struct entry *e; struct entry **pE; void *v; unsigned int hashvalue, index; hashvalue = hash(h,k); index = indexFor(h->tablelength,hash(h,k)); pE = &(h->table[index]); e = *pE; while (NULL != e) { /* Check hash value to short circuit heavier comparison */ if ((hashvalue == e->h) && (h->eqfn(k, e->k))) { *pE = e->next; h->entrycount--; v = e->v; freekey(e->k); free(e); return v; } pE = &(e->next); e = e->next; } return NULL; }