seahag/linkmap.c

146 lines
4.6 KiB
C

/* _,.---._ .-._ .--.-. ,--.--------.
* _,..---._ ,-.' , - `. /==/ \ .-._/==/ //==/, - , -\
* /==/, - \ /==/_, , - \|==|, \/ /, |==\ -\\==\.-. - ,-./
* |==| _ _\==| .=. |==|- \| | \==\- \`--`\==\- \
* |==| .=. |==|_ : ;=: - |==| , | -| `--`-' \==\_ \
* |==|,| | -|==| , '=' |==| - _ | |==|- |
* |==| '=' /\==\ - ,_ /|==| /\ , | |==|, |
* |==|-, _`/ '.='. - .' /==/, | |- | /==/ -/
* `-.`.____.' `--`--'' `--`./ `--` `--`--`
* _ __ ,---. .-._ .=-.-. _,.----.
* .-`.' ,`..--.' \ /==/ \ .-._ /==/_ /.' .' - \
* /==/, - \==\-/\ \ |==|, \/ /, /==|, |/==/ , ,-'
* |==| _ .=. /==/-|_\ | |==|- \| ||==| ||==|- | .
* |==| , '=',\==\, - \ |==| , | -||==|- ||==|_ `-' \
* |==|- '..'/==/ - ,| |==| - _ ||==| ,||==| _ , |
* |==|, | /==/- /\ - \|==| /\ , ||==|- |\==\. /
* /==/ - | \==\ _.\=\.-'/==/, | |- |/==/. / `-.`.___.-'
* `--`---' `--` `--`./ `--``--`-`
*
* @(#)Copyright (c) 2023, Nathan D. Fisher.
*
* This is free software. It comes with NO WARRANTY.
* Permission to use, modify and distribute this source code
* is granted subject to the following conditions.
* 1/ that the above copyright notice and this notice
* are preserved in all copies and that due credit be given
* to the author.
* 2/ that any changes to this code are clearly commented
* as such so that the author does not get blamed for bugs
* other than his own.
*/
#include "haggis.h"
#include "haggis_private.h"
#include <limits.h> // PATH_MAX
#include <stdio.h>
#include <stdlib.h> // calloc, free
#include <string.h> // strndup
#define FNV64_OFFSET_BASIS 14695981039346656037u
#define FNV64_PRIME 1099511628211u
uint64_t hash_fnv1a_64(uint8_t *key, size_t len) {
int i;
uint64_t hash = FNV64_OFFSET_BASIS;
for (i = 0; i < len; i++) {
hash = hash ^ *key;
hash = hash * FNV64_PRIME;
key++;
}
return hash;
}
uint64_t hash_str_fnv1a_64(char * s) {
uint64_t hash = FNV64_OFFSET_BASIS;
while (*s != '\0') {
hash = hash ^ *s;
hash = hash * FNV64_PRIME;
s++;
}
return hash;
}
haggis_linkmap* haggis_linkmap_init() {
haggis_linkmap *map;
map = calloc(1, sizeof(haggis_linkmap));
if (map == NULL)
return NULL;
map->buckets = calloc(HAGGIS_BUCKETS_BASE, sizeof(haggis_bucket));
if (map->buckets == NULL) {
free(map);
return NULL;
}
map->capacity = HAGGIS_BUCKETS_BASE;
return map;
}
void haggis_linkmap_deinit(haggis_linkmap *self) {
free(self->buckets);
free(self);
}
int haggis_linkmap_expand(haggis_linkmap *self) {
haggis_bucket *buckets_new;
haggis_bucket *buckets_old;
size_t i, idx;
buckets_new = calloc(self->capacity + HAGGIS_BUCKETS_BASE, sizeof(haggis_bucket));
if (buckets_new == NULL)
return 2;
for (i = 0; i < self->capacity + HAGGIS_BUCKETS_BASE; i++) {
self->buckets[i].path = NULL;
}
for (i = 0; i < self->capacity; i++) {
if (self->buckets[i].key != 0) {
self ->capacity += HAGGIS_BUCKETS_BASE;
idx = self->capacity % self->buckets[i].hash;
buckets_new[idx] = self->buckets[i];
}
}
buckets_old = self->buckets;
self->buckets = buckets_new;
free(buckets_old);
self->capacity += HAGGIS_BUCKETS_BASE;
return 0;
}
char* haggis_linkmap_get_or_add(haggis_linkmap *self, ino_t inode, char *path) {
union {
ino_t val;
u8 bytes[sizeof(ino_t)];
} key;
char * target = NULL;
size_t idx, hash, i;
haggis_bucket *bucket;
pthread_mutex_lock(&self->mutex);
if (self->len >= self->capacity)
haggis_linkmap_expand(self);
key.val = inode;
hash = hash_fnv1a_64(key.bytes, sizeof(ino_t));
idx = hash % self->capacity;
for (i = 0; i < self->capacity; i++) {
bucket = &self->buckets[idx];
if (bucket->key == inode) {
target = strndup(bucket->path, PATH_MAX - 1);
break;
} else if (bucket->key == 0) {
bucket->path = path;
bucket->key = inode;
bucket->hash = hash;
self->len++;
break;
} else {
idx++;
if (idx == self->capacity)
idx = 0;
}
}
pthread_mutex_unlock(&self->mutex);
return target;
}