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