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
hash_bits(size_t h,int bits)20 static 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
26 typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);
27 typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
28
29 struct hashmap_entry {
30 const void *key;
31 void *value;
32 struct hashmap_entry *next;
33 };
34
35 struct 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
56 void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
57 hashmap_equal_fn equal_fn, void *ctx);
58 struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
59 hashmap_equal_fn equal_fn,
60 void *ctx);
61 void hashmap__clear(struct hashmap *map);
62 void hashmap__free(struct hashmap *map);
63
64 size_t hashmap__size(const struct hashmap *map);
65 size_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 */
81 enum 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 */
95 int 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
hashmap__add(struct hashmap * map,const void * key,void * value)99 static 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
hashmap__set(struct hashmap * map,const void * key,void * value,const void ** old_key,void ** old_value)105 static 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
hashmap__update(struct hashmap * map,const void * key,void * value,const void ** old_key,void ** old_value)113 static 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
hashmap__append(struct hashmap * map,const void * key,void * value)121 static 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
127 bool hashmap__delete(struct hashmap *map, const void *key,
128 const void **old_key, void **old_value);
129
130 bool 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 */
179
