c语言实现带LRU机制的哈希表

 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

 #define HASH_BUCKET_MAX (1024)
 #define HASH_BUCKET_CAPACITY_MAX (256)
 #define HASHTABLE_DEBUG
 #define TRUE  1
 #define FALSE 0

 #ifdef HASHTABLE_DEBUG
 #define DEBUG(format, ...) printf("[%s] [%d] : "format"\n", __FUNCTION__, __LINE__, __VA_ARGS__)
 #else
 #define DEBUG(format, ...)
 #endif

 struct hash_bucket {
     int                capacity;  /* 桶的容量 */
     void               *hkey;     /* hashtable的key */
     void               *hdata;    /* hashtable的data */
     struct hash_bucket *prev;
     struct hash_bucket *next;
     struct hash_bucket *tail;
 };

 struct hash {
     uint32_t            (*hash_key)(void *);
     int                 (*hash_cmp)(const void *, const void*, int len);
     struct hash_bucket* bucket[HASH_BUCKET_MAX];
 };

 uint32_t string_hash_key(void* str);
 int string_hash_cmp(const void* src, const void* dst);

 static struct hash *g_htable = NULL;

 void hash_create();
 void *hash_lookup(void *key);
 int  hash_add(void *key, void* data);
 int  hash_delete(void *key);
 void hash_destroy();
 void hash_iter_print();

 #define  bucket_free(bucket) \
     free(bucket->hkey);      \
     free(bucket->hdata);     \
     free(bucket);            \
     bucket = NULL;

 uint32_t string_hash_key(void* str) {
     char *tmp = (char *)str;
     uint32_t key = ;
     while(*tmp)
         key = (key * ) ^ (uint32_t)(tmp++);

     DEBUG("string key : %u, index : %d", key, key%HASH_BUCKET_MAX);

     return key%HASH_BUCKET_MAX;
 }

 int string_hash_cmp(const void* src, const void* dst, int len) {
     if (!src || !dst) {
         DEBUG("src addr: %p, dst addr: %p", src, dst);
         return -;
     }
     return strncmp((char *)src, (char *)dst, len);
 }

 void hash_create() {
     if (g_htable) {
         DEBUG("the default hashtable is already created");
         return;
     }

     g_htable = (struct hash *)malloc(sizeof(struct hash));
     if (!g_htable) {
         DEBUG("memory alloc failed.");
         return;
     }

     memset(g_htable, , sizeof(struct hash));

     g_htable->hash_key = string_hash_key;
     g_htable->hash_cmp = string_hash_cmp;

     return;
 }

 static void bucket_delete(struct hash_bucket** ptr) {
     struct hash_bucket *bucket = *ptr;
     struct hash_bucket *tmp;

     while(bucket) {
         tmp = bucket;
         bucket = bucket->next;
         bucket_free(tmp);
     }
 }

 void hash_destroy() {
     if (g_htable) {
         for(int i=; i<HASH_BUCKET_MAX; i++) {
             if (g_htable->bucket[i]) {
                 bucket_delete(&g_htable->bucket[i]);
             }
         }

         free(g_htable);
         g_htable = NULL;
     }
     return;
 }

 #define  lru_bucket_move(bucket,  head)   \
     bucket->next = head;                  \
     bucket->prev = NULL;                  \
     bucket->capacity = head->capacity;    \
                                           \
     head->prev = bucket;                  \
     head->tail = NULL;    

 void *hash_lookup(void *key) {
     if (!key) {
         DEBUG("input para is NULL\n");
         return NULL;
     }

     uint32_t index = g_htable->hash_key(key);
     struct hash_bucket* head = g_htable->bucket[index];
     struct hash_bucket* bucket = head;

     while(bucket) {
         if ( == g_htable->hash_cmp(key, bucket->hkey, strlen((char*)key))) {
             if (head != bucket && bucket != head->tail) {
                 bucket->prev->next = bucket->next;
                 bucket->next->prev = bucket->prev;
                 bucket->tail = head->tail;

                 lru_bucket_move(bucket, head);
             } else if (bucket == head->tail && head->capacity>) {
                 bucket->prev->next = NULL;
                 bucket->tail = bucket->prev;

                 lru_bucket_move(bucket, head);
             }
             g_htable->bucket[index] = bucket;
             return bucket->hdata;
         }
         bucket = bucket->next;
     }
     return NULL;
 }

 int hash_add(void *key, void* data) {
     if (!key || !data) {
         DEBUG("input para is NULL\n");
         return FALSE;
     }

     uint32_t index = g_htable->hash_key(key);
     struct hash_bucket* head = g_htable->bucket[index];

     if (!head) {
         head = (struct hash_bucket*)malloc(sizeof(struct hash_bucket));
         if (!head) {
             DEBUG("no memory for more hash_bucket\n");
             return FALSE;
         }

         memset(head, , sizeof(*head));
         head->capacity++;

         head->hkey  = strdup((char *)key);
         head->hdata = strdup((char *)data);
         head->tail  = head;
         g_htable->bucket[index] = head;
         return TRUE;
     }

     int capacity = head->capacity;
     struct hash_bucket *new_bucket =
         (struct hash_bucket *)malloc(sizeof(struct hash_bucket)); 

     if (!new_bucket) {
         DEBUG("no memory for more hash_bucket\n");
         return FALSE;
     }

     if (capacity >= HASH_BUCKET_CAPACITY_MAX) {
         struct hash_bucket *tail = head->tail;
         head->tail = tail->prev;

         tail->prev->next = NULL;
         bucket_free(tail);
     } 

     head->prev = new_bucket;
     new_bucket->next = head;
     new_bucket->capacity = capacity + ;
     new_bucket->tail = head->tail;
     head->tail = NULL;

     head->hkey  = strdup((char *)key);
     head->hdata = strdup((char *)data);

     g_htable->bucket[index] = new_bucket;

     return TRUE;
 }

 int hash_delete(void *key) {
     if (!key) {
         DEBUG("input para is NULL\n");
         return FALSE;
     }

     uint32_t index = g_htable->hash_key(key);
     struct hash_bucket* head = g_htable->bucket[index];
     struct hash_bucket* bkt = head;

     while(bkt) {
         if ( == g_htable->hash_cmp(key, bkt->hkey, strlen((char*)key))) {
             if (head != bkt && bkt != head->tail) {
                 bkt->prev->next = bkt->next;
                 bkt->next->prev = bkt->prev;

             } else if (bkt == head->tail && head->capacity>) {
                 bkt->prev->next = NULL;
                 bkt->tail = bkt->prev;

             } else {
                 if (bkt->next) {
                     bkt->next->tail = bkt->tail;
                     bkt->next->capacity = bkt->capacity;
                     bkt->next->prev = NULL;
                     g_htable->bucket[index] = bkt->next;
                 } else {
                     g_htable->bucket[index] = NULL;
                 }
             }

             bucket_free(bkt);
             if (g_htable->bucket[index]) {
                 g_htable->bucket[index]->capacity--;
             }

             return TRUE;
         }
         bkt = bkt->next;
     }
     return FALSE;
 }

 static void bucket_print(struct hash_bucket** ptr) {
     struct hash_bucket *bkt = *ptr;
     struct hash_bucket *tmp;

     while(bkt) {
         printf("key=[%s],data=[%s]\n", (char*)bkt->hkey, (char*)bkt->hdata);
         bkt = bkt->next;
     }
 }

 void hash_iter_print() {
     if (g_htable) {
         for(int i=; i<HASH_BUCKET_MAX; i++) {
             if (g_htable->bucket[i]) {
                 bucket_print(&g_htable->bucket[i]);
             }
         }
     }
 }

 int main(int argc, char* argv[]) {
     hash_create();

     hash_add("first", "danxi");
     hash_add("second", "test");
     hash_add("three", "sad code");
     hash_add("four", "let's go");

     hash_iter_print();

     char * t1 = (char *)hash_lookup("first");
     char * t2 = (char *)hash_lookup("second");

     printf("%s  %s \n", t1, t2);
     printf("%s \n", (char*)hash_lookup("four"));

     hash_delete("four");
     hash_iter_print();
     hash_destroy();

     return ;
 }