1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
#include <string.h>
#include <stdio.h>
#include "uthash.h"
// this is an example of how to do a LRU cache in C using uthash
// https://troydhanson.github.io/uthash/
// by Jehiah Czebotar 2011 - jehiah@gmail.com
// this code is in the public domain http://unlicense.org/
#define MAX_CACHE_SIZE 50U /* a real value would be much larger */
struct CacheEntry {
char *key;
char *value;
UT_hash_handle hh;
};
struct CacheEntry *cache = NULL;
static void add_to_cache(const char *key, const char *value)
{
struct CacheEntry *entry, *tmp_entry;
entry = (struct CacheEntry *)malloc(sizeof(struct CacheEntry));
if (entry == NULL) {
exit(-1);
}
entry->key = strdup(key);
entry->value = strdup(value);
HASH_ADD_KEYPTR(hh, cache, entry->key, strlen(entry->key), entry);
// prune the cache to MAX_CACHE_SIZE
if (HASH_COUNT(cache) >= MAX_CACHE_SIZE) {
HASH_ITER(hh, cache, entry, tmp_entry) {
// prune the first entry (loop is based on insertion order so this deletes the oldest item)
printf("LRU deleting %s %s\n", entry->key, entry->value);
HASH_DELETE(hh, cache, entry);
free(entry->key);
free(entry->value);
free(entry);
break;
}
}
}
/* main added by Troy D. Hanson */
int main()
{
char linebuf[100];
char nbuf[11];
FILE *file;
unsigned int i=0;
file = fopen( "test65.dat", "r" );
if (file == NULL) {
perror("can't open: ");
exit(-1);
}
while (fgets(linebuf,sizeof(linebuf),file) != NULL) {
snprintf(nbuf,sizeof(nbuf),"%u",i++);
add_to_cache(linebuf, nbuf);
}
fclose(file);
return 0;
}
|