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。
#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_ */
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 20
struct 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。
原文：http://blog.csdn.net/pngynghay/article/details/21882521