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)(long key, void *ctx);
 44typedef bool (*hashmap_equal_fn)(long key1, long key2, void *ctx);
 45
 46/*
 47 * Hashmap interface is polymorphic, keys and values could be either
 48 * long-sized integers or pointers, this is achieved as follows:
 49 * - interface functions that operate on keys and values are hidden
 50 *   behind auxiliary macros, e.g. hashmap_insert <-> hashmap__insert;
 51 * - these auxiliary macros cast the key and value parameters as
 52 *   long or long *, so the user does not have to specify the casts explicitly;
 53 * - for pointer parameters (e.g. old_key) the size of the pointed
 54 *   type is verified by hashmap_cast_ptr using _Static_assert;
 55 * - when iterating using hashmap__for_each_* forms
 56 *   hasmap_entry->key should be used for integer keys and
 57 *   hasmap_entry->pkey should be used for pointer keys,
 58 *   same goes for values.
 59 */
 60struct hashmap_entry {
 61	union {
 62		long key;
 63		const void *pkey;
 64	};
 65	union {
 66		long value;
 67		void *pvalue;
 68	};
 69	struct hashmap_entry *next;
 70};
 71
 72struct hashmap {
 73	hashmap_hash_fn hash_fn;
 74	hashmap_equal_fn equal_fn;
 75	void *ctx;
 76
 77	struct hashmap_entry **buckets;
 78	size_t cap;
 79	size_t cap_bits;
 80	size_t sz;
 81};
 82
 83#define HASHMAP_INIT(hash_fn, equal_fn, ctx) {	\
 84	.hash_fn = (hash_fn),			\
 85	.equal_fn = (equal_fn),			\
 86	.ctx = (ctx),				\
 87	.buckets = NULL,			\
 88	.cap = 0,				\
 89	.cap_bits = 0,				\
 90	.sz = 0,				\
 91}
 92
 93void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
 94		   hashmap_equal_fn equal_fn, void *ctx);
 95struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
 96			     hashmap_equal_fn equal_fn,
 97			     void *ctx);
 98void hashmap__clear(struct hashmap *map);
 99void hashmap__free(struct hashmap *map);
100
101size_t hashmap__size(const struct hashmap *map);
102size_t hashmap__capacity(const struct hashmap *map);
103
104/*
105 * Hashmap insertion strategy:
106 * - HASHMAP_ADD - only add key/value if key doesn't exist yet;
107 * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
108 *   update value;
109 * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do
110 *   nothing and return -ENOENT;
111 * - HASHMAP_APPEND - always add key/value pair, even if key already exists.
112 *   This turns hashmap into a multimap by allowing multiple values to be
113 *   associated with the same key. Most useful read API for such hashmap is
114 *   hashmap__for_each_key_entry() iteration. If hashmap__find() is still
115 *   used, it will return last inserted key/value entry (first in a bucket
116 *   chain).
117 */
118enum hashmap_insert_strategy {
119	HASHMAP_ADD,
120	HASHMAP_SET,
121	HASHMAP_UPDATE,
122	HASHMAP_APPEND,
123};
124
125#define hashmap_cast_ptr(p) ({								\
126	_Static_assert((__builtin_constant_p((p)) ? (p) == NULL : 0) ||			\
127				sizeof(*(p)) == sizeof(long),				\
128		       #p " pointee should be a long-sized integer or a pointer");	\
129	(long *)(p);									\
130})
131
132/*
133 * hashmap__insert() adds key/value entry w/ various semantics, depending on
134 * provided strategy value. If a given key/value pair replaced already
135 * existing key/value pair, both old key and old value will be returned
136 * through old_key and old_value to allow calling code do proper memory
137 * management.
138 */
139int hashmap_insert(struct hashmap *map, long key, long value,
140		   enum hashmap_insert_strategy strategy,
141		   long *old_key, long *old_value);
142
143#define hashmap__insert(map, key, value, strategy, old_key, old_value) \
144	hashmap_insert((map), (long)(key), (long)(value), (strategy),  \
145		       hashmap_cast_ptr(old_key),		       \
146		       hashmap_cast_ptr(old_value))
147
148#define hashmap__add(map, key, value) \
149	hashmap__insert((map), (key), (value), HASHMAP_ADD, NULL, NULL)
150
151#define hashmap__set(map, key, value, old_key, old_value) \
152	hashmap__insert((map), (key), (value), HASHMAP_SET, (old_key), (old_value))
153
154#define hashmap__update(map, key, value, old_key, old_value) \
155	hashmap__insert((map), (key), (value), HASHMAP_UPDATE, (old_key), (old_value))
156
157#define hashmap__append(map, key, value) \
158	hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL)
159
160bool hashmap_delete(struct hashmap *map, long key, long *old_key, long *old_value);
161
162#define hashmap__delete(map, key, old_key, old_value)		       \
163	hashmap_delete((map), (long)(key),			       \
164		       hashmap_cast_ptr(old_key),		       \
165		       hashmap_cast_ptr(old_value))
166
167bool hashmap_find(const struct hashmap *map, long key, long *value);
168
169#define hashmap__find(map, key, value) \
170	hashmap_find((map), (long)(key), hashmap_cast_ptr(value))
171
172/*
173 * hashmap__for_each_entry - iterate over all entries in hashmap
174 * @map: hashmap to iterate
175 * @cur: struct hashmap_entry * used as a loop cursor
176 * @bkt: integer used as a bucket loop cursor
177 */
178#define hashmap__for_each_entry(map, cur, bkt)				    \
179	for (bkt = 0; bkt < map->cap; bkt++)				    \
180		for (cur = map->buckets[bkt]; cur; cur = cur->next)
181
182/*
183 * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe
184 * against removals
185 * @map: hashmap to iterate
186 * @cur: struct hashmap_entry * used as a loop cursor
187 * @tmp: struct hashmap_entry * used as a temporary next cursor storage
188 * @bkt: integer used as a bucket loop cursor
189 */
190#define hashmap__for_each_entry_safe(map, cur, tmp, bkt)		    \
191	for (bkt = 0; bkt < map->cap; bkt++)				    \
192		for (cur = map->buckets[bkt];				    \
193		     cur && ({tmp = cur->next; true; });		    \
194		     cur = tmp)
195
196/*
197 * hashmap__for_each_key_entry - iterate over entries associated with given key
198 * @map: hashmap to iterate
199 * @cur: struct hashmap_entry * used as a loop cursor
200 * @key: key to iterate entries for
201 */
202#define hashmap__for_each_key_entry(map, cur, _key)			    \
203	for (cur = map->buckets						    \
204		     ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
205		     : NULL;						    \
206	     cur;							    \
207	     cur = cur->next)						    \
208		if (map->equal_fn(cur->key, (_key), map->ctx))
209
210#define hashmap__for_each_key_entry_safe(map, cur, tmp, _key)		    \
211	for (cur = map->buckets						    \
212		     ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
213		     : NULL;						    \
214	     cur && ({ tmp = cur->next; true; });			    \
215	     cur = tmp)							    \
216		if (map->equal_fn(cur->key, (_key), map->ctx))
217
218#endif /* __LIBBPF_HASHMAP_H */