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Diffstat (limited to 'tools/lib/bpf/hashmap.h')
| -rw-r--r-- | tools/lib/bpf/hashmap.h | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/tools/lib/bpf/hashmap.h b/tools/lib/bpf/hashmap.h new file mode 100644 index 0000000000..c12f8320e6 --- /dev/null +++ b/tools/lib/bpf/hashmap.h @@ -0,0 +1,208 @@ +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ + +/* + * Generic non-thread safe hash map implementation. + * + * Copyright (c) 2019 Facebook + */ +#ifndef __LIBBPF_HASHMAP_H +#define __LIBBPF_HASHMAP_H + +#include <stdbool.h> +#include <stddef.h> +#include <limits.h> + +static inline size_t hash_bits(size_t h, int bits) +{ + /* shuffle bits and return requested number of upper bits */ + if (bits == 0) + return 0; + +#if (__SIZEOF_SIZE_T__ == __SIZEOF_LONG_LONG__) + /* LP64 case */ + return (h * 11400714819323198485llu) >> (__SIZEOF_LONG_LONG__ * 8 - bits); +#elif (__SIZEOF_SIZE_T__ <= __SIZEOF_LONG__) + return (h * 2654435769lu) >> (__SIZEOF_LONG__ * 8 - bits); +#else +# error "Unsupported size_t size" +#endif +} + +/* generic C-string hashing function */ +static inline size_t str_hash(const char *s) +{ + size_t h = 0; + + while (*s) { + h = h * 31 + *s; + s++; + } + return h; +} + +typedef size_t (*hashmap_hash_fn)(long key, void *ctx); +typedef bool (*hashmap_equal_fn)(long key1, long key2, void *ctx); + +/* + * Hashmap interface is polymorphic, keys and values could be either + * long-sized integers or pointers, this is achieved as follows: + * - interface functions that operate on keys and values are hidden + * behind auxiliary macros, e.g. hashmap_insert <-> hashmap__insert; + * - these auxiliary macros cast the key and value parameters as + * long or long *, so the user does not have to specify the casts explicitly; + * - for pointer parameters (e.g. old_key) the size of the pointed + * type is verified by hashmap_cast_ptr using _Static_assert; + * - when iterating using hashmap__for_each_* forms + * hasmap_entry->key should be used for integer keys and + * hasmap_entry->pkey should be used for pointer keys, + * same goes for values. + */ +struct hashmap_entry { + union { + long key; + const void *pkey; + }; + union { + long value; + void *pvalue; + }; + struct hashmap_entry *next; +}; + +struct hashmap { + hashmap_hash_fn hash_fn; + hashmap_equal_fn equal_fn; + void *ctx; + + struct hashmap_entry **buckets; + size_t cap; + size_t cap_bits; + size_t sz; +}; + +void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn, + hashmap_equal_fn equal_fn, void *ctx); +struct hashmap *hashmap__new(hashmap_hash_fn hash_fn, + hashmap_equal_fn equal_fn, + void *ctx); +void hashmap__clear(struct hashmap *map); +void hashmap__free(struct hashmap *map); + +size_t hashmap__size(const struct hashmap *map); +size_t hashmap__capacity(const struct hashmap *map); + +/* + * Hashmap insertion strategy: + * - HASHMAP_ADD - only add key/value if key doesn't exist yet; + * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise, + * update value; + * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do + * nothing and return -ENOENT; + * - HASHMAP_APPEND - always add key/value pair, even if key already exists. + * This turns hashmap into a multimap by allowing multiple values to be + * associated with the same key. Most useful read API for such hashmap is + * hashmap__for_each_key_entry() iteration. If hashmap__find() is still + * used, it will return last inserted key/value entry (first in a bucket + * chain). + */ +enum hashmap_insert_strategy { + HASHMAP_ADD, + HASHMAP_SET, + HASHMAP_UPDATE, + HASHMAP_APPEND, +}; + +#define hashmap_cast_ptr(p) ({ \ + _Static_assert((__builtin_constant_p((p)) ? (p) == NULL : 0) || \ + sizeof(*(p)) == sizeof(long), \ + #p " pointee should be a long-sized integer or a pointer"); \ + (long *)(p); \ +}) + +/* + * hashmap__insert() adds key/value entry w/ various semantics, depending on + * provided strategy value. If a given key/value pair replaced already + * existing key/value pair, both old key and old value will be returned + * through old_key and old_value to allow calling code do proper memory + * management. + */ +int hashmap_insert(struct hashmap *map, long key, long value, + enum hashmap_insert_strategy strategy, + long *old_key, long *old_value); + +#define hashmap__insert(map, key, value, strategy, old_key, old_value) \ + hashmap_insert((map), (long)(key), (long)(value), (strategy), \ + hashmap_cast_ptr(old_key), \ + hashmap_cast_ptr(old_value)) + +#define hashmap__add(map, key, value) \ + hashmap__insert((map), (key), (value), HASHMAP_ADD, NULL, NULL) + +#define hashmap__set(map, key, value, old_key, old_value) \ + hashmap__insert((map), (key), (value), HASHMAP_SET, (old_key), (old_value)) + +#define hashmap__update(map, key, value, old_key, old_value) \ + hashmap__insert((map), (key), (value), HASHMAP_UPDATE, (old_key), (old_value)) + +#define hashmap__append(map, key, value) \ + hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL) + +bool hashmap_delete(struct hashmap *map, long key, long *old_key, long *old_value); + +#define hashmap__delete(map, key, old_key, old_value) \ + hashmap_delete((map), (long)(key), \ + hashmap_cast_ptr(old_key), \ + hashmap_cast_ptr(old_value)) + +bool hashmap_find(const struct hashmap *map, long key, long *value); + +#define hashmap__find(map, key, value) \ + hashmap_find((map), (long)(key), hashmap_cast_ptr(value)) + +/* + * hashmap__for_each_entry - iterate over all entries in hashmap + * @map: hashmap to iterate + * @cur: struct hashmap_entry * used as a loop cursor + * @bkt: integer used as a bucket loop cursor + */ +#define hashmap__for_each_entry(map, cur, bkt) \ + for (bkt = 0; bkt < map->cap; bkt++) \ + for (cur = map->buckets[bkt]; cur; cur = cur->next) + +/* + * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe + * against removals + * @map: hashmap to iterate + * @cur: struct hashmap_entry * used as a loop cursor + * @tmp: struct hashmap_entry * used as a temporary next cursor storage + * @bkt: integer used as a bucket loop cursor + */ +#define hashmap__for_each_entry_safe(map, cur, tmp, bkt) \ + for (bkt = 0; bkt < map->cap; bkt++) \ + for (cur = map->buckets[bkt]; \ + cur && ({tmp = cur->next; true; }); \ + cur = tmp) + +/* + * hashmap__for_each_key_entry - iterate over entries associated with given key + * @map: hashmap to iterate + * @cur: struct hashmap_entry * used as a loop cursor + * @key: key to iterate entries for + */ +#define hashmap__for_each_key_entry(map, cur, _key) \ + for (cur = map->buckets \ + ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \ + : NULL; \ + cur; \ + cur = cur->next) \ + if (map->equal_fn(cur->key, (_key), map->ctx)) + +#define hashmap__for_each_key_entry_safe(map, cur, tmp, _key) \ + for (cur = map->buckets \ + ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \ + : NULL; \ + cur && ({ tmp = cur->next; true; }); \ + cur = tmp) \ + if (map->equal_fn(cur->key, (_key), map->ctx)) + +#endif /* __LIBBPF_HASHMAP_H */ |