hash链表

hash链表概述

hash链表是hash表和链表的结合，使用比较方便。

hash链表实现

本文的hash链表实现：hash头部用单链表、其他的hash节点用双向链表。实现主要取自Linux内核实现，本文做了移植。本文代码可从http://download.csdn.net/detail/it_pcode/6632905下载。

hash实现

#ifndef HLIST_H_#define HLIST_H_#include <stdlib.h>#include <stddef.h>#include <stdio.h>#include <time.h>#include <string.h>/*通过父结构体type中的成员member的已知地址ptr，来寻找当前ptr地址所属的父结构体type的地址*/#define container_of(ptr, type, member) ({ \const typeof( ((type *)0)->member ) *__mptr = (ptr); \(type *)( (char *)__mptr - offsetof(type,member) );})/*内核预加载内容到RAM，在此不做实现*/#define prefetch(x) (x)/* * Double linked lists with a single pointer list head. * Mostly useful for hash tables where the two pointer list head is * too wasteful. * You lose the ability to access the tail in O(1). */struct hlist_head {struct hlist_node *first;};struct hlist_node {struct hlist_node *next, **pprev;};#define HLIST_HEAD_INIT { .first = NULL }#define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)static inline void INIT_HLIST_NODE(struct hlist_node *h) {h->next = NULL;h->pprev = NULL;}static inline int hlist_unhashed(const struct hlist_node *h) {return !h->pprev;}static inline int hlist_empty(const struct hlist_head *h) {return !h->first;}static inline void __hlist_del(struct hlist_node *n) {struct hlist_node *next = n->next;struct hlist_node **pprev = n->pprev;*pprev = next;if (next)next->pprev = pprev;}static inline void hlist_del(struct hlist_node *n) {__hlist_del(n);n->next = NULL;n->pprev = NULL;}static inline void hlist_del_init(struct hlist_node *n) {if (!hlist_unhashed(n)) {__hlist_del(n);INIT_HLIST_NODE(n);}}static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) {struct hlist_node *first = h->first;n->next = first;if (first)first->pprev = &n->next;h->first = n;n->pprev = &h->first;}/* next must be != NULL */static inline void hlist_add_before(struct hlist_node *n,struct hlist_node *next) {n->pprev = next->pprev;n->next = next;next->pprev = &n->next;*(n->pprev) = n;}static inline void hlist_add_after(struct hlist_node *n,struct hlist_node *next) {next->next = n->next;n->next = next;next->pprev = &n->next;if (next->next)next->next->pprev = &next->next;}/* * Move a list from one list head to another. Fixup the pprev * reference of the first entry if it exists. */static inline void hlist_move_list(struct hlist_head *old,struct hlist_head *new) {new->first = old->first;if (new->first)new->first->pprev = &new->first;old->first = NULL;}#define hlist_entry(ptr, type, member) container_of(ptr,type,member)#define hlist_for_each(pos, head) \for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \     pos = pos->next)#define hlist_for_each_safe(pos, n, head) \for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \     pos = n)/** * hlist_for_each_entry- iterate over list of given type * @tpos:the type * to use as a loop cursor. * @pos:the &struct hlist_node to use as a loop cursor. * @head:the head for your list. * @member:the name of the hlist_node within the struct. */#define hlist_for_each_entry(tpos, pos, head, member) \for (pos = (head)->first; \     pos && ({ prefetch(pos->next); 1;}) && \({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \     pos = pos->next)/** * hlist_for_each_entry_continue - iterate over a hlist continuing after current point * @tpos:the type * to use as a loop cursor. * @pos:the &struct hlist_node to use as a loop cursor. * @member:the name of the hlist_node within the struct. */#define hlist_for_each_entry_continue(tpos, pos, member) \for (pos = (pos)->next; \     pos && ({ prefetch(pos->next); 1;}) && \({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \     pos = pos->next)/** * hlist_for_each_entry_from - iterate over a hlist continuing from current point * @tpos:the type * to use as a loop cursor. * @pos:the &struct hlist_node to use as a loop cursor. * @member:the name of the hlist_node within the struct. */#define hlist_for_each_entry_from(tpos, pos, member) \for (; pos && ({ prefetch(pos->next); 1;}) && \({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \     pos = pos->next)/** * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry * @tpos:the type * to use as a loop cursor. * @pos:the &struct hlist_node to use as a loop cursor. * @n:another &struct hlist_node to use as temporary storage * @head:the head for your list. * @member:the name of the hlist_node within the struct. */#define hlist_for_each_entry_safe(tpos, pos, n, head, member)  \for (pos = (head)->first; \     pos && ({ n = pos->next; 1; }) &&  \({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \     pos = n)#endif /* HLIST_H_ */

hash链表实例

首先实现了自己的hash list初始化、键存在与否判定以及key值查找等函数。然后是主测试程序。

#define MAX_LEN 20struct hash_node {struct hlist_node hnode;int age;};struct hlist_head hashead[MAX_LEN];void init_hlist() {int i = 0;for (i = 0; i < MAX_LEN; i++) {INIT_HLIST_HEAD(&hashead[i]);}}int key_exists(struct hlist_head *head, int key) {struct hash_node * node;struct hlist_node *hlistnode;hlist_for_each_entry(node, hlistnode, head,hnode) {if (node->age == key) {return 1;}}return 0;}struct hash_node * hlist_search(int age) {struct hash_node *node, *data;int i = 0;struct hlist_node *hlistnode;for (i = 0; i < MAX_LEN; i++) {hlist_for_each_entry(node, hlistnode, &hashead[i],hnode) {data = container_of(&node->hnode, struct hash_node, hnode);if (data->age == age) {return data;}}}return NULL;}void testhlist() {init_hlist();int i = 0;struct hash_node * node;struct hlist_node *hlistnode;srand(time(NULL));for (i = 0; i < 4 * MAX_LEN; i++) {node = malloc(sizeof(struct hash_node));INIT_HLIST_NODE(&node->hnode);node->age = rand() % (4 * MAX_LEN);if (key_exists(&hashead[node->age % MAX_LEN], node->age) == 0) {hlist_add_head(&node->hnode, &hashead[node->age % MAX_LEN]);}}for (i = 0; i < MAX_LEN; i++) {printf("head %d has member :", i);hlist_for_each_entry(node, hlistnode, &hashead[i],hnode) {printf("%d  ", node->age);}printf("\n");}for (i = 0; i < MAX_LEN; i++) {node = hlist_search(i);if (NULL != node) {printf("found %d\n", i);hlist_del(&node->hnode);}}printf("after clear \n");for (i = 0; i < MAX_LEN; i++) {printf("head %d has member :", i);hlist_for_each_entry(node, hlistnode, &hashead[i],hnode) {printf("%d  ", node->age);}printf("\n");}}

在main函数里，调用主测试程序即可。