/* 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 */
Codebase Browser
linux