blob: 246fb34df9ed60e4f57054ea98322cb8d532ed14 [file] [log] [blame]
/**
* @file hash_table.c
* @author Radek Krejci <rkrejci@cesnet.cz>
* @author Michal Vasko <mvasko@cesnet.cz>
* @brief libyang generic hash table implementation
*
* Copyright (c) 2015 - 2023 CESNET, z.s.p.o.
*
* This source code is licensed under BSD 3-Clause License (the "License").
* You may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://opensource.org/licenses/BSD-3-Clause
*/
#include "hash_table.h"
#include <assert.h>
#include <pthread.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "common.h"
#include "compat.h"
#include "dict.h"
#include "log.h"
LIBYANG_API_DEF uint32_t
lyht_hash_multi(uint32_t hash, const char *key_part, size_t len)
{
uint32_t i;
if (key_part && len) {
for (i = 0; i < len; ++i) {
hash += key_part[i];
hash += (hash << 10);
hash ^= (hash >> 6);
}
} else {
hash += (hash << 3);
hash ^= (hash >> 11);
hash += (hash << 15);
}
return hash;
}
LIBYANG_API_DEF uint32_t
lyht_hash(const char *key, size_t len)
{
uint32_t hash;
hash = lyht_hash_multi(0, key, len);
return lyht_hash_multi(hash, NULL, len);
}
struct ly_ht_rec *
lyht_get_rec(unsigned char *recs, uint16_t rec_size, uint32_t idx)
{
return (struct ly_ht_rec *)&recs[idx * rec_size];
}
LIBYANG_API_DEF struct ly_ht *
lyht_new(uint32_t size, uint16_t val_size, lyht_value_equal_cb val_equal, void *cb_data, uint16_t resize)
{
struct ly_ht *ht;
/* check that 2^x == size (power of 2) */
assert(size && !(size & (size - 1)));
assert(val_equal && val_size);
assert(resize == 0 || resize == 1);
if (size < LYHT_MIN_SIZE) {
size = LYHT_MIN_SIZE;
}
ht = malloc(sizeof *ht);
LY_CHECK_ERR_RET(!ht, LOGMEM(NULL), NULL);
ht->used = 0;
ht->size = size;
ht->invalid = 0;
ht->val_equal = val_equal;
ht->cb_data = cb_data;
ht->resize = resize;
ht->rec_size = (sizeof(struct ly_ht_rec) - 1) + val_size;
/* allocate the records correctly */
ht->recs = calloc(size, ht->rec_size);
LY_CHECK_ERR_RET(!ht->recs, free(ht); LOGMEM(NULL), NULL);
return ht;
}
LIBYANG_API_DEF lyht_value_equal_cb
lyht_set_cb(struct ly_ht *ht, lyht_value_equal_cb new_val_equal)
{
lyht_value_equal_cb prev;
prev = ht->val_equal;
ht->val_equal = new_val_equal;
return prev;
}
LIBYANG_API_DEF void *
lyht_set_cb_data(struct ly_ht *ht, void *new_cb_data)
{
void *prev;
prev = ht->cb_data;
ht->cb_data = new_cb_data;
return prev;
}
LIBYANG_API_DEF struct ly_ht *
lyht_dup(const struct ly_ht *orig)
{
struct ly_ht *ht;
LY_CHECK_ARG_RET(NULL, orig, NULL);
ht = lyht_new(orig->size, orig->rec_size - (sizeof(struct ly_ht_rec) - 1), orig->val_equal, orig->cb_data, orig->resize ? 1 : 0);
if (!ht) {
return NULL;
}
memcpy(ht->recs, orig->recs, (size_t)orig->used * (size_t)orig->rec_size);
ht->used = orig->used;
ht->invalid = orig->invalid;
return ht;
}
LIBYANG_API_DEF void
lyht_free(struct ly_ht *ht, void (*val_free)(void *val_p))
{
struct ly_ht_rec *rec;
uint32_t i;
if (!ht) {
return;
}
if (val_free) {
for (i = 0; i < ht->size; ++i) {
rec = lyht_get_rec(ht->recs, ht->rec_size, i);
if (rec->hits > 0) {
val_free(&rec->val);
}
}
}
free(ht->recs);
free(ht);
}
/**
* @brief Resize a hash table.
*
* @param[in] ht Hash table to resize.
* @param[in] operation Operation to perform. 1 to enlarge, -1 to shrink, 0 to only rehash all records.
* @return LY_ERR value.
*/
static LY_ERR
lyht_resize(struct ly_ht *ht, int operation)
{
struct ly_ht_rec *rec;
unsigned char *old_recs;
uint32_t i, old_size;
old_recs = ht->recs;
old_size = ht->size;
if (operation > 0) {
/* double the size */
ht->size <<= 1;
} else if (operation < 0) {
/* half the size */
ht->size >>= 1;
}
ht->recs = calloc(ht->size, ht->rec_size);
LY_CHECK_ERR_RET(!ht->recs, LOGMEM(NULL); ht->recs = old_recs; ht->size = old_size, LY_EMEM);
/* reset used and invalid, it will increase again */
ht->used = 0;
ht->invalid = 0;
/* add all the old records into the new records array */
for (i = 0; i < old_size; ++i) {
rec = lyht_get_rec(old_recs, ht->rec_size, i);
if (rec->hits > 0) {
LY_ERR ret = lyht_insert(ht, rec->val, rec->hash, NULL);
assert(!ret);
(void)ret;
}
}
/* final touches */
free(old_recs);
return LY_SUCCESS;
}
/**
* @brief Search for the first match.
*
* @param[in] ht Hash table to search in.
* @param[in] hash Hash to find.
* @param[out] rec_p Optional found record.
* @return LY_SUCCESS hash found, returned its record,
* @return LY_ENOTFOUND hash not found, returned the record where it would be inserted.
*/
static LY_ERR
lyht_find_first(struct ly_ht *ht, uint32_t hash, struct ly_ht_rec **rec_p)
{
struct ly_ht_rec *rec;
uint32_t i, idx;
if (rec_p) {
*rec_p = NULL;
}
idx = i = hash & (ht->size - 1);
rec = lyht_get_rec(ht->recs, ht->rec_size, idx);
/* skip through overflow and deleted records */
while ((rec->hits != 0) && ((rec->hits == -1) || ((rec->hash & (ht->size - 1)) != idx))) {
if ((rec->hits == -1) && rec_p && !(*rec_p)) {
/* remember this record for return */
*rec_p = rec;
}
i = (i + 1) % ht->size;
if (i == idx) {
/* we went through all the records (very unlikely, but possible when many records are invalid),
* just return not found */
assert(!rec_p || *rec_p);
return LY_ENOTFOUND;
}
rec = lyht_get_rec(ht->recs, ht->rec_size, i);
}
if (rec->hits == 0) {
/* we could not find the value */
if (rec_p && !*rec_p) {
*rec_p = rec;
}
return LY_ENOTFOUND;
}
/* we have found a record with equal (shortened) hash */
if (rec_p) {
*rec_p = rec;
}
return LY_SUCCESS;
}
/**
* @brief Search for the next collision.
*
* @param[in] ht Hash table to search in.
* @param[in,out] last Last returned collision record.
* @param[in] first First collision record (hits > 1).
* @return LY_SUCCESS when hash collision found, \p last points to this next collision,
* @return LY_ENOTFOUND when hash collision not found, \p last points to the record where it would be inserted.
*/
static LY_ERR
lyht_find_collision(struct ly_ht *ht, struct ly_ht_rec **last, struct ly_ht_rec *first)
{
struct ly_ht_rec *empty = NULL;
uint32_t i, idx;
assert(last && *last);
idx = (*last)->hash & (ht->size - 1);
i = (((unsigned char *)*last) - ht->recs) / ht->rec_size;
do {
i = (i + 1) % ht->size;
*last = lyht_get_rec(ht->recs, ht->rec_size, i);
if (*last == first) {
/* we went through all the records (very unlikely, but possible when many records are invalid),
* just return an invalid record */
assert(empty);
*last = empty;
return LY_ENOTFOUND;
}
if (((*last)->hits == -1) && !empty) {
empty = *last;
}
} while (((*last)->hits != 0) && (((*last)->hits == -1) || (((*last)->hash & (ht->size - 1)) != idx)));
if ((*last)->hits > 0) {
/* we found a collision */
assert((*last)->hits == 1);
return LY_SUCCESS;
}
/* no next collision found, return the record where it would be inserted */
if (empty) {
*last = empty;
} /* else (*last)->hits == 0, it is already correct */
return LY_ENOTFOUND;
}
/**
* @brief Search for a record with specific value and hash.
*
* @param[in] ht Hash table to search in.
* @param[in] val_p Pointer to the value to find.
* @param[in] hash Hash to find.
* @param[in] mod Whether the operation modifies the hash table (insert or remove) or not (find).
* @param[out] crec_p Optional found first record.
* @param[out] col Optional collision number of @p rec_p, 0 for no collision.
* @param[out] rec_p Found exact matching record, may be a collision of @p crec_p.
* @return LY_ENOTFOUND if no record found,
* @return LY_SUCCESS if record was found.
*/
static LY_ERR
lyht_find_rec(struct ly_ht *ht, void *val_p, uint32_t hash, ly_bool mod, struct ly_ht_rec **crec_p, uint32_t *col,
struct ly_ht_rec **rec_p)
{
struct ly_ht_rec *rec, *crec;
uint32_t i, c;
LY_ERR r;
if (crec_p) {
*crec_p = NULL;
}
if (col) {
*col = 0;
}
*rec_p = NULL;
if (lyht_find_first(ht, hash, &rec)) {
/* not found */
return LY_ENOTFOUND;
}
if ((rec->hash == hash) && ht->val_equal(val_p, &rec->val, mod, ht->cb_data)) {
/* even the value matches */
if (crec_p) {
*crec_p = rec;
}
if (col) {
*col = 0;
}
*rec_p = rec;
return LY_SUCCESS;
}
/* some collisions, we need to go through them, too */
crec = rec;
c = crec->hits;
for (i = 1; i < c; ++i) {
r = lyht_find_collision(ht, &rec, crec);
assert(!r);
(void)r;
/* compare values */
if ((rec->hash == hash) && ht->val_equal(val_p, &rec->val, mod, ht->cb_data)) {
if (crec_p) {
*crec_p = crec;
}
if (col) {
*col = i;
}
*rec_p = rec;
return LY_SUCCESS;
}
}
/* not found even in collisions */
return LY_ENOTFOUND;
}
LIBYANG_API_DEF LY_ERR
lyht_find(struct ly_ht *ht, void *val_p, uint32_t hash, void **match_p)
{
struct ly_ht_rec *rec;
lyht_find_rec(ht, val_p, hash, 0, NULL, NULL, &rec);
if (rec && match_p) {
*match_p = rec->val;
}
return rec ? LY_SUCCESS : LY_ENOTFOUND;
}
LIBYANG_API_DEF LY_ERR
lyht_find_next_with_collision_cb(struct ly_ht *ht, void *val_p, uint32_t hash,
lyht_value_equal_cb collision_val_equal, void **match_p)
{
struct ly_ht_rec *rec, *crec;
uint32_t i, c;
LY_ERR r;
/* find the record of the previously found value */
if (lyht_find_rec(ht, val_p, hash, 1, &crec, &i, &rec)) {
/* not found, cannot happen */
LOGINT_RET(NULL);
}
/* go through collisions and find the next one after the previous one */
c = crec->hits;
for (++i; i < c; ++i) {
r = lyht_find_collision(ht, &rec, crec);
assert(!r);
(void)r;
if (rec->hash != hash) {
continue;
}
if (collision_val_equal) {
if (collision_val_equal(val_p, &rec->val, 0, ht->cb_data)) {
/* even the value matches */
if (match_p) {
*match_p = rec->val;
}
return LY_SUCCESS;
}
} else if (ht->val_equal(val_p, &rec->val, 0, ht->cb_data)) {
/* even the value matches */
if (match_p) {
*match_p = rec->val;
}
return LY_SUCCESS;
}
}
/* the last equal value was already returned */
return LY_ENOTFOUND;
}
LIBYANG_API_DEF LY_ERR
lyht_find_next(struct ly_ht *ht, void *val_p, uint32_t hash, void **match_p)
{
return lyht_find_next_with_collision_cb(ht, val_p, hash, NULL, match_p);
}
LIBYANG_API_DEF LY_ERR
lyht_insert_with_resize_cb(struct ly_ht *ht, void *val_p, uint32_t hash, lyht_value_equal_cb resize_val_equal,
void **match_p)
{
LY_ERR r, ret = LY_SUCCESS;
struct ly_ht_rec *rec, *crec = NULL;
int32_t i;
lyht_value_equal_cb old_val_equal = NULL;
if (!lyht_find_first(ht, hash, &rec)) {
/* we found matching shortened hash */
if ((rec->hash == hash) && ht->val_equal(val_p, &rec->val, 1, ht->cb_data)) {
/* even the value matches */
if (match_p) {
*match_p = (void *)&rec->val;
}
return LY_EEXIST;
}
/* some collisions, we need to go through them, too */
crec = rec;
for (i = 1; i < crec->hits; ++i) {
r = lyht_find_collision(ht, &rec, crec);
assert(!r);
/* compare values */
if ((rec->hash == hash) && ht->val_equal(val_p, &rec->val, 1, ht->cb_data)) {
if (match_p) {
*match_p = (void *)&rec->val;
}
return LY_EEXIST;
}
}
/* value not found, get the record where it will be inserted */
r = lyht_find_collision(ht, &rec, crec);
assert(r);
}
/* insert it into the returned record */
assert(rec->hits < 1);
if (rec->hits < 0) {
--ht->invalid;
}
rec->hash = hash;
rec->hits = 1;
memcpy(&rec->val, val_p, ht->rec_size - (sizeof(struct ly_ht_rec) - 1));
if (match_p) {
*match_p = (void *)&rec->val;
}
if (crec) {
/* there was a collision, increase hits */
if (crec->hits == INT32_MAX) {
LOGINT(NULL);
}
++crec->hits;
}
/* check size & enlarge if needed */
++ht->used;
if (ht->resize) {
r = (ht->used * LYHT_HUNDRED_PERCENTAGE) / ht->size;
if ((ht->resize == 1) && (r >= LYHT_FIRST_SHRINK_PERCENTAGE)) {
/* enable shrinking */
ht->resize = 2;
}
if ((ht->resize == 2) && (r >= LYHT_ENLARGE_PERCENTAGE)) {
if (resize_val_equal) {
old_val_equal = lyht_set_cb(ht, resize_val_equal);
}
/* enlarge */
ret = lyht_resize(ht, 1);
/* if hash_table was resized, we need to find new matching value */
if ((ret == LY_SUCCESS) && match_p) {
lyht_find(ht, val_p, hash, match_p);
}
if (resize_val_equal) {
lyht_set_cb(ht, old_val_equal);
}
}
}
return ret;
}
LIBYANG_API_DEF LY_ERR
lyht_insert(struct ly_ht *ht, void *val_p, uint32_t hash, void **match_p)
{
return lyht_insert_with_resize_cb(ht, val_p, hash, NULL, match_p);
}
LIBYANG_API_DEF LY_ERR
lyht_remove_with_resize_cb(struct ly_ht *ht, void *val_p, uint32_t hash, lyht_value_equal_cb resize_val_equal)
{
struct ly_ht_rec *rec, *crec;
int32_t i;
ly_bool first_matched = 0;
LY_ERR r, ret = LY_SUCCESS;
lyht_value_equal_cb old_val_equal = NULL;
LY_CHECK_ERR_RET(lyht_find_first(ht, hash, &rec), LOGARG(NULL, hash), LY_ENOTFOUND); /* hash not found */
if ((rec->hash == hash) && ht->val_equal(val_p, &rec->val, 1, ht->cb_data)) {
/* even the value matches */
first_matched = 1;
}
/* we always need to go through collisions */
crec = rec;
for (i = 1; i < crec->hits; ++i) {
r = lyht_find_collision(ht, &rec, crec);
assert(!r);
/* compare values */
if (!first_matched && (rec->hash == hash) && ht->val_equal(val_p, &rec->val, 1, ht->cb_data)) {
break;
}
}
if (i < crec->hits) {
/* one of collisions matched, reduce collision count, remove the record */
assert(!first_matched);
--crec->hits;
rec->hits = -1;
} else if (first_matched) {
/* the first record matches */
if (crec != rec) {
/* ... so put the last collision in its place */
rec->hits = crec->hits - 1;
memcpy(crec, rec, ht->rec_size);
}
rec->hits = -1;
} else {
/* value not found even in collisions */
return LY_ENOTFOUND;
}
/* check size & shrink if needed */
--ht->used;
++ht->invalid;
if (ht->resize == 2) {
r = (ht->used * LYHT_HUNDRED_PERCENTAGE) / ht->size;
if ((r < LYHT_SHRINK_PERCENTAGE) && (ht->size > LYHT_MIN_SIZE)) {
if (resize_val_equal) {
old_val_equal = lyht_set_cb(ht, resize_val_equal);
}
/* shrink */
ret = lyht_resize(ht, -1);
if (resize_val_equal) {
lyht_set_cb(ht, old_val_equal);
}
}
}
/* rehash all records if needed */
r = ((ht->size - ht->used - ht->invalid) * 100) / ht->size;
if (r < LYHT_REHASH_PERCENTAGE) {
if (resize_val_equal) {
old_val_equal = lyht_set_cb(ht, resize_val_equal);
}
/* rehash */
ret = lyht_resize(ht, 0);
if (resize_val_equal) {
lyht_set_cb(ht, old_val_equal);
}
}
return ret;
}
LIBYANG_API_DEF LY_ERR
lyht_remove(struct ly_ht *ht, void *val_p, uint32_t hash)
{
return lyht_remove_with_resize_cb(ht, val_p, hash, NULL);
}
LIBYANG_API_DEF uint32_t
lyht_get_fixed_size(uint32_t item_count)
{
uint32_t i, size = 0;
/* detect number of upper zero bits in the items' counter value ... */
for (i = (sizeof item_count * CHAR_BIT) - 1; i > 0; i--) {
size = item_count << i;
size = size >> i;
if (size == item_count) {
break;
}
}
assert(i);
/* ... and then we convert it to the position of the highest non-zero bit ... */
i = (sizeof item_count * CHAR_BIT) - i;
/* ... and by using it to shift 1 to the left we get the closest sufficient hash table size */
size = 1 << i;
return size;
}