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