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| -rw-r--r-- | src/hash_table.h | 259 |
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diff --git a/src/hash_table.h b/src/hash_table.h new file mode 100644 index 0000000..5780f1e --- /dev/null +++ b/src/hash_table.h @@ -0,0 +1,259 @@ +/** + * @file hash_table.h + * @author Radek Krejci <rkrejci@cesnet.cz> + * @author Michal Vasko <mvasko@cesnet.cz> + * @brief libyang hash table + * + * Copyright (c) 2015 - 2023 CESNET, z.s.p.o. + * + * This source code is licensed under BSD 3-Clause License (the "License"). + * You may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * https://opensource.org/licenses/BSD-3-Clause + */ + +#ifndef LY_HASH_TABLE_H_ +#define LY_HASH_TABLE_H_ + +#include <stddef.h> +#include <stdint.h> + +#ifdef __cplusplus +extern "C" { +#endif + +#include "log.h" + +/** + * @struct ly_ht + * @brief libyang hash table. + */ +struct ly_ht; + +/** + * @brief Compute hash from (several) string(s). + * + * Usage: + * - init hash to 0 + * - repeatedly call ::lyht_hash_multi(), provide hash from the last call + * - call ::lyht_hash_multi() with key_part = NULL to finish the hash + * + * @param[in] hash Previous hash. + * @param[in] key_part Next key to hash, + * @param[in] len Length of @p key_part. + * @return Hash with the next key. + */ +LIBYANG_API_DECL uint32_t lyht_hash_multi(uint32_t hash, const char *key_part, size_t len); + +/** + * @brief Compute hash from a string. + * + * Bob Jenkin's one-at-a-time hash + * http://www.burtleburtle.net/bob/hash/doobs.html + * + * Spooky hash is faster, but it works only for little endian architectures. + * + * @param[in] key Key to hash. + * @param[in] len Length of @p key. + * @return Hash of the key. + */ +LIBYANG_API_DECL uint32_t lyht_hash(const char *key, size_t len); + +/** + * @brief Callback for checking hash table values equivalence. + * + * @param[in] val1_p Pointer to the first value, the one being searched (inserted/removed). + * @param[in] val2_p Pointer to the second value, the one stored in the hash table. + * @param[in] mod Whether the operation modifies the hash table (insert or remove) or not (find). + * @param[in] cb_data User callback data. + * @return false (non-equal) or true (equal). + */ +typedef ly_bool (*lyht_value_equal_cb)(void *val1_p, void *val2_p, ly_bool mod, void *cb_data); + +/** + * @brief Create new hash table. + * + * @param[in] size Starting size of the hash table (capacity of values), must be power of 2. + * @param[in] val_size Size in bytes of value (the stored hashed item). + * @param[in] val_equal Callback for checking value equivalence. + * @param[in] cb_data User data always passed to @p val_equal. + * @param[in] resize Whether to resize the table on too few/too many records taken. + * @return Empty hash table, NULL on error. + */ +LIBYANG_API_DECL struct ly_ht *lyht_new(uint32_t size, uint16_t val_size, lyht_value_equal_cb val_equal, void *cb_data, + uint16_t resize); + +/** + * @brief Set hash table value equal callback. + * + * @param[in] ht Hash table to modify. + * @param[in] new_val_equal New callback for checking value equivalence. + * @return Previous callback for checking value equivalence. + */ +LIBYANG_API_DECL lyht_value_equal_cb lyht_set_cb(struct ly_ht *ht, lyht_value_equal_cb new_val_equal); + +/** + * @brief Set hash table value equal callback user data. + * + * @param[in] ht Hash table to modify. + * @param[in] new_cb_data New data for values callback. + * @return Previous data for values callback. + */ +LIBYANG_API_DECL void *lyht_set_cb_data(struct ly_ht *ht, void *new_cb_data); + +/** + * @brief Make a duplicate of an existing hash table. + * + * @param[in] orig Original hash table to duplicate. + * @return Duplicated hash table @p orig, NULL on error. + */ +LIBYANG_API_DECL struct ly_ht *lyht_dup(const struct ly_ht *orig); + +/** + * @brief Free a hash table. + * + * @param[in] ht Hash table to be freed. + * @param[in] val_free Optional callback for freeing all the stored values, @p val_p is a pointer to a stored value. + */ +LIBYANG_API_DECL void lyht_free(struct ly_ht *ht, void (*val_free)(void *val_p)); + +/** + * @brief Find a value in a hash table. + * + * @param[in] ht Hash table to search in. + * @param[in] val_p Pointer to the value to find. + * @param[in] hash Hash of the stored value. + * @param[out] match_p Pointer to the matching value, optional. + * @return LY_SUCCESS if value was found, + * @return LY_ENOTFOUND if not found. + */ +LIBYANG_API_DECL LY_ERR lyht_find(const struct ly_ht *ht, void *val_p, uint32_t hash, void **match_p); + +/** + * @brief Find a value in a hash table but use a custom val_equal callback. + * + * @param[in] ht Hash table to search in. + * @param[in] val_p Pointer to the value to find. + * @param[in] hash Hash of the stored value. + * @param[in] val_equal Callback for checking value equivalence. + * @param[out] match_p Pointer to the matching value, optional. + * @return LY_SUCCESS if value was found, + * @return LY_ENOTFOUND if not found. + */ +LIBYANG_API_DECL LY_ERR lyht_find_with_val_cb(const struct ly_ht *ht, void *val_p, uint32_t hash, + lyht_value_equal_cb val_equal, void **match_p); + +/** + * @brief Find another equal value in the hash table. + * + * @param[in] ht Hash table to search in. + * @param[in] val_p Pointer to the previously found value in @p ht. + * @param[in] hash Hash of the previously found value. + * @param[out] match_p Pointer to the matching value, optional. + * @return LY_SUCCESS if value was found, + * @return LY_ENOTFOUND if not found. + */ +LIBYANG_API_DECL LY_ERR lyht_find_next(const struct ly_ht *ht, void *val_p, uint32_t hash, void **match_p); + +/** + * @brief Find another equal value in the hash table. Same functionality as ::lyht_find_next() + * but allows to specify a collision val equal callback to be used for checking for matching colliding values. + * + * @param[in] ht Hash table to search in. + * @param[in] val_p Pointer to the previously found value in @p ht. + * @param[in] hash Hash of the previously found value. + * @param[in] collision_val_equal Val equal callback to use for checking collisions. + * @param[out] match_p Pointer to the matching value, optional. + * @return LY_SUCCESS if value was found, + * @return LY_ENOTFOUND if not found. + */ +LIBYANG_API_DECL LY_ERR lyht_find_next_with_collision_cb(const struct ly_ht *ht, void *val_p, uint32_t hash, + lyht_value_equal_cb collision_val_equal, void **match_p); + +/** + * @brief Insert a value into a hash table. + * + * @param[in] ht Hash table to insert into. + * @param[in] val_p Pointer to the value to insert. Be careful, if the values stored in the hash table + * are pointers, @p val_p must be a pointer to a pointer. + * @param[in] hash Hash of the stored value. + * @param[out] match_p Pointer to the stored value, optional + * @return LY_SUCCESS on success, + * @return LY_EEXIST in case the value is already present. + * @return LY_EMEM in case of memory allocation failure. + */ +LIBYANG_API_DECL LY_ERR lyht_insert(struct ly_ht *ht, void *val_p, uint32_t hash, void **match_p); + +/** + * @brief Insert a value into a hash table, without checking whether the value has already been inserted. + * + * @param[in] ht Hash table to insert into. + * @param[in] val_p Pointer to the value to insert. Be careful, if the values stored in the hash table + * are pointers, @p val_p must be a pointer to a pointer. + * @param[in] hash Hash of the stored value. + * @param[out] match_p Pointer to the stored value, optional + * @return LY_SUCCESS on success, + * @return LY_EMEM in case of memory allocation failure. + */ +LIBYANG_API_DECL LY_ERR lyht_insert_no_check(struct ly_ht *ht, void *val_p, uint32_t hash, void **match_p); + +/** + * @brief Insert a value into hash table. Same functionality as ::lyht_insert() + * but allows to specify a temporary val equal callback to be used in case the hash table + * will be resized after successful insertion. + * + * @param[in] ht Hash table to insert into. + * @param[in] val_p Pointer to the value to insert. Be careful, if the values stored in the hash table + * are pointers, @p val_p must be a pointer to a pointer. + * @param[in] hash Hash of the stored value. + * @param[in] resize_val_equal Val equal callback to use for resizing. + * @param[out] match_p Pointer to the stored value, optional + * @return LY_SUCCESS on success, + * @return LY_EEXIST in case the value is already present. + * @return LY_EMEM in case of memory allocation failure. + */ +LIBYANG_API_DECL LY_ERR lyht_insert_with_resize_cb(struct ly_ht *ht, void *val_p, uint32_t hash, + lyht_value_equal_cb resize_val_equal, void **match_p); + +/** + * @brief Remove a value from a hash table. + * + * @param[in] ht Hash table to remove from. + * @param[in] val_p Pointer to value to be removed. Be careful, if the values stored in the hash table + * are pointers, @p val_p must be a pointer to a pointer. + * @param[in] hash Hash of the stored value. + * @return LY_SUCCESS on success, + * @return LY_ENOTFOUND if value was not found. + */ +LIBYANG_API_DECL LY_ERR lyht_remove(struct ly_ht *ht, void *val_p, uint32_t hash); + +/** + * @brief Remove a value from a hash table. Same functionality as ::lyht_remove() + * but allows to specify a temporary val equal callback to be used in case the hash table + * will be resized after successful removal. + * + * @param[in] ht Hash table to remove from. + * @param[in] val_p Pointer to value to be removed. Be careful, if the values stored in the hash table + * are pointers, @p val_p must be a pointer to a pointer. + * @param[in] hash Hash of the stored value. + * @param[in] resize_val_equal Val equal callback to use for resizing. + * @return LY_SUCCESS on success, + * @return LY_ENOTFOUND if value was not found. + */ +LIBYANG_API_DECL LY_ERR lyht_remove_with_resize_cb(struct ly_ht *ht, void *val_p, uint32_t hash, + lyht_value_equal_cb resize_val_equal); + +/** + * @brief Get suitable size of a hash table for a fixed number of items. + * + * @param[in] item_count Number of stored items. + * @return Hash table size. + */ +LIBYANG_API_DECL uint32_t lyht_get_fixed_size(uint32_t item_count); + +#ifdef __cplusplus +} +#endif + +#endif /* LY_HASH_TABLE_H_ */ |