ares_htable.h (6517B)
1 /* MIT License 2 * 3 * Copyright (c) 2023 Brad House 4 * 5 * Permission is hereby granted, free of charge, to any person obtaining a copy 6 * of this software and associated documentation files (the "Software"), to deal 7 * in the Software without restriction, including without limitation the rights 8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 * copies of the Software, and to permit persons to whom the Software is 10 * furnished to do so, subject to the following conditions: 11 * 12 * The above copyright notice and this permission notice (including the next 13 * paragraph) shall be included in all copies or substantial portions of the 14 * Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 * SOFTWARE. 23 * 24 * SPDX-License-Identifier: MIT 25 */ 26 #ifndef __ARES__HTABLE_H 27 #define __ARES__HTABLE_H 28 29 30 /*! \addtogroup ares_htable Base HashTable Data Structure 31 * 32 * This is a basic hashtable data structure that is meant to be wrapped 33 * by a higher level implementation. This data structure is designed to 34 * be callback-based in order to facilitate wrapping without needing to 35 * worry about any underlying complexities of the hashtable implementation. 36 * 37 * This implementation supports automatic growing by powers of 2 when reaching 38 * 75% capacity. A rehash will be performed on the expanded bucket list. 39 * 40 * Average time complexity: 41 * - Insert: O(1) 42 * - Search: O(1) 43 * - Delete: O(1) 44 * 45 * @{ 46 */ 47 48 struct ares_htable; 49 50 /*! Opaque data type for generic hash table implementation */ 51 typedef struct ares_htable ares_htable_t; 52 53 /*! Callback for generating a hash of the key. 54 * 55 * \param[in] key pointer to key to be hashed 56 * \param[in] seed randomly generated seed used by hash function. 57 * value is specific to the hashtable instance 58 * but otherwise will not change between calls. 59 * \return hash 60 */ 61 typedef unsigned int (*ares_htable_hashfunc_t)(const void *key, 62 unsigned int seed); 63 64 /*! Callback to free the bucket 65 * 66 * \param[in] bucket user provided bucket 67 */ 68 typedef void (*ares_htable_bucket_free_t)(void *bucket); 69 70 /*! Callback to extract the key from the user-provided bucket 71 * 72 * \param[in] bucket user provided bucket 73 * \return pointer to key held in bucket 74 */ 75 typedef const void *(*ares_htable_bucket_key_t)(const void *bucket); 76 77 /*! Callback to compare two keys for equality 78 * 79 * \param[in] key1 first key 80 * \param[in] key2 second key 81 * \return ARES_TRUE if equal, ARES_FALSE if not 82 */ 83 typedef ares_bool_t (*ares_htable_key_eq_t)(const void *key1, const void *key2); 84 85 86 /*! Destroy the initialized hashtable 87 * 88 * \param[in] htable initialized hashtable 89 */ 90 void ares_htable_destroy(ares_htable_t *htable); 91 92 /*! Create a new hashtable 93 * 94 * \param[in] hash_func Required. Callback for Hash function. 95 * \param[in] bucket_key Required. Callback to extract key from bucket. 96 * \param[in] bucket_free Required. Callback to free bucket. 97 * \param[in] key_eq Required. Callback to check for key equality. 98 * \return initialized hashtable. NULL if out of memory or misuse. 99 */ 100 ares_htable_t *ares_htable_create(ares_htable_hashfunc_t hash_func, 101 ares_htable_bucket_key_t bucket_key, 102 ares_htable_bucket_free_t bucket_free, 103 ares_htable_key_eq_t key_eq); 104 105 /*! Count of keys from initialized hashtable 106 * 107 * \param[in] htable Initialized hashtable. 108 * \return count of keys 109 */ 110 size_t ares_htable_num_keys(const ares_htable_t *htable); 111 112 /*! Retrieve an array of buckets from the hashtable. This is mainly used as 113 * a helper for retrieving an array of keys. 114 * 115 * \param[in] htable Initialized hashtable 116 * \param[out] num Count of returned buckets 117 * \return Array of pointers to the buckets. These are internal pointers 118 * to data within the hashtable, so if the key is removed, there 119 * will be a dangling pointer. It is expected wrappers will make 120 * such values safe by duplicating them. 121 */ 122 const void **ares_htable_all_buckets(const ares_htable_t *htable, size_t *num); 123 124 /*! Insert bucket into hashtable 125 * 126 * \param[in] htable Initialized hashtable. 127 * \param[in] bucket User-provided bucket to insert. Takes "ownership". Not 128 * allowed to be NULL. 129 * \return ARES_TRUE on success, ARES_FALSE if out of memory 130 */ 131 ares_bool_t ares_htable_insert(ares_htable_t *htable, void *bucket); 132 133 /*! Retrieve bucket from hashtable based on key. 134 * 135 * \param[in] htable Initialized hashtable 136 * \param[in] key Pointer to key to use for comparison. 137 * \return matching bucket, or NULL if not found. 138 */ 139 void *ares_htable_get(const ares_htable_t *htable, const void *key); 140 141 /*! Remove bucket from hashtable by key 142 * 143 * \param[in] htable Initialized hashtable 144 * \param[in] key Pointer to key to use for comparison 145 * \return ARES_TRUE if found, ARES_FALSE if not found 146 */ 147 ares_bool_t ares_htable_remove(ares_htable_t *htable, const void *key); 148 149 /*! FNV1a hash algorithm. Can be used as underlying primitive for building 150 * a wrapper hashtable. 151 * 152 * \param[in] key pointer to key 153 * \param[in] key_len Length of key 154 * \param[in] seed Seed for generating hash 155 * \return hash value 156 */ 157 unsigned int ares_htable_hash_FNV1a(const unsigned char *key, size_t key_len, 158 unsigned int seed); 159 160 /*! FNV1a hash algorithm, but converts all characters to lowercase before 161 * hashing to make the hash case-insensitive. Can be used as underlying 162 * primitive for building a wrapper hashtable. Used on string-based keys. 163 * 164 * \param[in] key pointer to key 165 * \param[in] key_len Length of key 166 * \param[in] seed Seed for generating hash 167 * \return hash value 168 */ 169 unsigned int ares_htable_hash_FNV1a_casecmp(const unsigned char *key, 170 size_t key_len, unsigned int seed); 171 172 /*! @} */ 173 174 #endif /* __ARES__HTABLE_H */