230 lines
4.6 KiB
C
230 lines
4.6 KiB
C
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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
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/*
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* Generic non-thread safe hash map implementation.
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*
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* Copyright (c) 2019 Facebook
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <errno.h>
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#include <linux/err.h>
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#include "hashmap.h"
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/* start with 4 buckets */
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#define HASHMAP_MIN_CAP_BITS 2
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static void hashmap_add_entry(struct hashmap_entry **pprev,
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struct hashmap_entry *entry)
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{
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entry->next = *pprev;
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*pprev = entry;
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}
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static void hashmap_del_entry(struct hashmap_entry **pprev,
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struct hashmap_entry *entry)
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{
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*pprev = entry->next;
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entry->next = NULL;
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}
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void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
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hashmap_equal_fn equal_fn, void *ctx)
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{
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map->hash_fn = hash_fn;
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map->equal_fn = equal_fn;
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map->ctx = ctx;
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map->buckets = NULL;
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map->cap = 0;
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map->cap_bits = 0;
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map->sz = 0;
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}
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struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
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hashmap_equal_fn equal_fn,
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void *ctx)
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{
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struct hashmap *map = malloc(sizeof(struct hashmap));
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if (!map)
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return ERR_PTR(-ENOMEM);
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hashmap__init(map, hash_fn, equal_fn, ctx);
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return map;
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}
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void hashmap__clear(struct hashmap *map)
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{
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free(map->buckets);
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map->cap = map->cap_bits = map->sz = 0;
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}
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void hashmap__free(struct hashmap *map)
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{
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if (!map)
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return;
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hashmap__clear(map);
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free(map);
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}
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size_t hashmap__size(const struct hashmap *map)
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{
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return map->sz;
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}
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size_t hashmap__capacity(const struct hashmap *map)
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{
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return map->cap;
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}
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static bool hashmap_needs_to_grow(struct hashmap *map)
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{
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/* grow if empty or more than 75% filled */
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return (map->cap == 0) || ((map->sz + 1) * 4 / 3 > map->cap);
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}
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static int hashmap_grow(struct hashmap *map)
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{
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struct hashmap_entry **new_buckets;
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struct hashmap_entry *cur, *tmp;
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size_t new_cap_bits, new_cap;
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size_t h;
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int bkt;
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new_cap_bits = map->cap_bits + 1;
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if (new_cap_bits < HASHMAP_MIN_CAP_BITS)
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new_cap_bits = HASHMAP_MIN_CAP_BITS;
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new_cap = 1UL << new_cap_bits;
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new_buckets = calloc(new_cap, sizeof(new_buckets[0]));
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if (!new_buckets)
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return -ENOMEM;
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hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
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h = hash_bits(map->hash_fn(cur->key, map->ctx), new_cap_bits);
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hashmap_add_entry(&new_buckets[h], cur);
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}
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map->cap = new_cap;
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map->cap_bits = new_cap_bits;
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free(map->buckets);
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map->buckets = new_buckets;
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return 0;
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}
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static bool hashmap_find_entry(const struct hashmap *map,
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const void *key, size_t hash,
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struct hashmap_entry ***pprev,
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struct hashmap_entry **entry)
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{
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struct hashmap_entry *cur, **prev_ptr;
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if (!map->buckets)
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return false;
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for (prev_ptr = &map->buckets[hash], cur = *prev_ptr;
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cur;
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prev_ptr = &cur->next, cur = cur->next) {
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if (map->equal_fn(cur->key, key, map->ctx)) {
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if (pprev)
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*pprev = prev_ptr;
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*entry = cur;
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return true;
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}
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}
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return false;
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}
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int hashmap__insert(struct hashmap *map, const void *key, void *value,
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enum hashmap_insert_strategy strategy,
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const void **old_key, void **old_value)
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{
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struct hashmap_entry *entry;
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size_t h;
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int err;
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if (old_key)
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*old_key = NULL;
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if (old_value)
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*old_value = NULL;
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h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
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if (strategy != HASHMAP_APPEND &&
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hashmap_find_entry(map, key, h, NULL, &entry)) {
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if (old_key)
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*old_key = entry->key;
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if (old_value)
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*old_value = entry->value;
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if (strategy == HASHMAP_SET || strategy == HASHMAP_UPDATE) {
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entry->key = key;
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entry->value = value;
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return 0;
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} else if (strategy == HASHMAP_ADD) {
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return -EEXIST;
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}
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}
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if (strategy == HASHMAP_UPDATE)
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return -ENOENT;
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if (hashmap_needs_to_grow(map)) {
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err = hashmap_grow(map);
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if (err)
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return err;
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h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
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}
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entry = malloc(sizeof(struct hashmap_entry));
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if (!entry)
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return -ENOMEM;
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entry->key = key;
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entry->value = value;
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hashmap_add_entry(&map->buckets[h], entry);
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map->sz++;
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return 0;
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}
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bool hashmap__find(const struct hashmap *map, const void *key, void **value)
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{
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struct hashmap_entry *entry;
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size_t h;
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h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
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if (!hashmap_find_entry(map, key, h, NULL, &entry))
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return false;
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if (value)
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*value = entry->value;
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return true;
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}
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bool hashmap__delete(struct hashmap *map, const void *key,
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const void **old_key, void **old_value)
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{
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struct hashmap_entry **pprev, *entry;
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size_t h;
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h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
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if (!hashmap_find_entry(map, key, h, &pprev, &entry))
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return false;
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if (old_key)
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*old_key = entry->key;
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if (old_value)
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*old_value = entry->value;
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hashmap_del_entry(pprev, entry);
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free(entry);
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map->sz--;
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return true;
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}
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