1/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
  2
  3/*
  4 * Generic non-thread safe hash map implementation.
  5 *
  6 * Copyright (c) 2019 Facebook
  7 */
  8#ifndef __LIBBPF_HASHMAP_H
  9#define __LIBBPF_HASHMAP_H
 10
 11#include <stdbool.h>
 12#include <stddef.h>
 13#include <limits.h>
 14
 15static inline size_t hash_bits(size_t h, int bits)
 16{
 17	/* shuffle bits and return requested number of upper bits */
 18	if (bits == 0)
 19		return 0;
 20
 21#if (__SIZEOF_SIZE_T__ == __SIZEOF_LONG_LONG__)
 22	/* LP64 case */
 23	return (h * 11400714819323198485llu) >> (__SIZEOF_LONG_LONG__ * 8 - bits);
 24#elif (__SIZEOF_SIZE_T__ <= __SIZEOF_LONG__)
 25	return (h * 2654435769lu) >> (__SIZEOF_LONG__ * 8 - bits);
 26#else
 27#	error "Unsupported size_t size"
 28#endif
 29}
 30
 31/* generic C-string hashing function */
 32static inline size_t str_hash(const char *s)
 33{
 34	size_t h = 0;
 35
 36	while (*s) {
 37		h = h * 31 + *s;
 38		s++;
 39	}
 40	return h;
 41}
 42
 43typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);
 44typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
 45
 46struct hashmap_entry {
 47	const void *key;
 48	void *value;
 49	struct hashmap_entry *next;
 50};
 51
 52struct hashmap {
 53	hashmap_hash_fn hash_fn;
 54	hashmap_equal_fn equal_fn;
 55	void *ctx;
 56
 57	struct hashmap_entry **buckets;
 58	size_t cap;
 59	size_t cap_bits;
 60	size_t sz;
 61};
 62
 63#define HASHMAP_INIT(hash_fn, equal_fn, ctx) {	\
 64	.hash_fn = (hash_fn),			\
 65	.equal_fn = (equal_fn),			\
 66	.ctx = (ctx),				\
 67	.buckets = NULL,			\
 68	.cap = 0,				\
 69	.cap_bits = 0,				\
 70	.sz = 0,				\
 71}
 72
 73void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
 74		   hashmap_equal_fn equal_fn, void *ctx);
 75struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
 76			     hashmap_equal_fn equal_fn,
 77			     void *ctx);
 78void hashmap__clear(struct hashmap *map);
 79void hashmap__free(struct hashmap *map);
 80
 81size_t hashmap__size(const struct hashmap *map);
 82size_t hashmap__capacity(const struct hashmap *map);
 83
 84/*
 85 * Hashmap insertion strategy:
 86 * - HASHMAP_ADD - only add key/value if key doesn't exist yet;
 87 * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
 88 *   update value;
 89 * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do
 90 *   nothing and return -ENOENT;
 91 * - HASHMAP_APPEND - always add key/value pair, even if key already exists.
 92 *   This turns hashmap into a multimap by allowing multiple values to be
 93 *   associated with the same key. Most useful read API for such hashmap is
 94 *   hashmap__for_each_key_entry() iteration. If hashmap__find() is still
 95 *   used, it will return last inserted key/value entry (first in a bucket
 96 *   chain).
 97 */
 98enum hashmap_insert_strategy {
 99	HASHMAP_ADD,
100	HASHMAP_SET,
101	HASHMAP_UPDATE,
102	HASHMAP_APPEND,
103};
104
105/*
106 * hashmap__insert() adds key/value entry w/ various semantics, depending on
107 * provided strategy value. If a given key/value pair replaced already
108 * existing key/value pair, both old key and old value will be returned
109 * through old_key and old_value to allow calling code do proper memory
110 * management.
111 */
112int hashmap__insert(struct hashmap *map, const void *key, void *value,
113		    enum hashmap_insert_strategy strategy,
114		    const void **old_key, void **old_value);
115
116static inline int hashmap__add(struct hashmap *map,
117			       const void *key, void *value)
118{
119	return hashmap__insert(map, key, value, HASHMAP_ADD, NULL, NULL);
120}
121
122static inline int hashmap__set(struct hashmap *map,
123			       const void *key, void *value,
124			       const void **old_key, void **old_value)
125{
126	return hashmap__insert(map, key, value, HASHMAP_SET,
127			       old_key, old_value);
128}
129
130static inline int hashmap__update(struct hashmap *map,
131				  const void *key, void *value,
132				  const void **old_key, void **old_value)
133{
134	return hashmap__insert(map, key, value, HASHMAP_UPDATE,
135			       old_key, old_value);
136}
137
138static inline int hashmap__append(struct hashmap *map,
139				  const void *key, void *value)
140{
141	return hashmap__insert(map, key, value, HASHMAP_APPEND, NULL, NULL);
142}
143
144bool hashmap__delete(struct hashmap *map, const void *key,
145		     const void **old_key, void **old_value);
146
147bool hashmap__find(const struct hashmap *map, const void *key, void **value);
148
149/*
150 * hashmap__for_each_entry - iterate over all entries in hashmap
151 * @map: hashmap to iterate
152 * @cur: struct hashmap_entry * used as a loop cursor
153 * @bkt: integer used as a bucket loop cursor
154 */
155#define hashmap__for_each_entry(map, cur, bkt)				    \
156	for (bkt = 0; bkt < map->cap; bkt++)				    \
157		for (cur = map->buckets[bkt]; cur; cur = cur->next)
158
159/*
160 * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe
161 * against removals
162 * @map: hashmap to iterate
163 * @cur: struct hashmap_entry * used as a loop cursor
164 * @tmp: struct hashmap_entry * used as a temporary next cursor storage
165 * @bkt: integer used as a bucket loop cursor
166 */
167#define hashmap__for_each_entry_safe(map, cur, tmp, bkt)		    \
168	for (bkt = 0; bkt < map->cap; bkt++)				    \
169		for (cur = map->buckets[bkt];				    \
170		     cur && ({tmp = cur->next; true; });		    \
171		     cur = tmp)
172
173/*
174 * hashmap__for_each_key_entry - iterate over entries associated with given key
175 * @map: hashmap to iterate
176 * @cur: struct hashmap_entry * used as a loop cursor
177 * @key: key to iterate entries for
178 */
179#define hashmap__for_each_key_entry(map, cur, _key)			    \
180	for (cur = map->buckets						    \
181		     ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
182		     : NULL;						    \
183	     cur;							    \
184	     cur = cur->next)						    \
185		if (map->equal_fn(cur->key, (_key), map->ctx))
186
187#define hashmap__for_each_key_entry_safe(map, cur, tmp, _key)		    \
188	for (cur = map->buckets						    \
189		     ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
190		     : NULL;						    \
191	     cur && ({ tmp = cur->next; true; });			    \
192	     cur = tmp)							    \
193		if (map->equal_fn(cur->key, (_key), map->ctx))
194
195#endif /* __LIBBPF_HASHMAP_H */