1 /* SPDX-License-Identifier: BSD-3-Clause 2 * Copyright(c) 2010-2014 Intel Corporation 3 */ 4 5 #ifndef _RTE_FBK_HASH_H_ 6 #define _RTE_FBK_HASH_H_ 7 8 /** 9 * @file 10 * 11 * This is a hash table implementation for four byte keys (fbk). 12 * 13 * Note that the return value of the add function should always be checked as, 14 * if a bucket is full, the key is not added even if there is space in other 15 * buckets. This keeps the lookup function very simple and therefore fast. 16 */ 17 18 #include <stdint.h> 19 #include <errno.h> 20 21 #include <string.h> 22 23 #include <rte_hash_crc.h> 24 #include <rte_jhash.h> 25 26 #ifdef __cplusplus 27 extern "C" { 28 #endif 29 30 #ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT 31 /** Initialising value used when calculating hash. */ 32 #define RTE_FBK_HASH_INIT_VAL_DEFAULT 0xFFFFFFFF 33 #endif 34 35 /** The maximum number of entries in the hash table that is supported. */ 36 #define RTE_FBK_HASH_ENTRIES_MAX (1 << 20) 37 38 /** The maximum number of entries in each bucket that is supported. */ 39 #define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX 256 40 41 /** Maximum size of string for naming the hash. */ 42 #define RTE_FBK_HASH_NAMESIZE 32 43 44 /** Type of function that can be used for calculating the hash value. */ 45 typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val); 46 47 /** Parameters used when creating four-byte key hash table. */ 48 struct rte_fbk_hash_params { 49 const char *name; /**< Name of the hash table. */ 50 uint32_t entries; /**< Total number of entries. */ 51 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */ 52 int socket_id; /**< Socket to allocate memory on. */ 53 rte_fbk_hash_fn hash_func; /**< The hash function. */ 54 uint32_t init_val; /**< For initialising hash function. */ 55 }; 56 57 /** Individual entry in the four-byte key hash table. */ 58 union rte_fbk_hash_entry { 59 uint64_t whole_entry; /**< For accessing entire entry. */ 60 struct { 61 uint16_t is_entry; /**< Non-zero if entry is active. */ 62 uint16_t value; /**< Value returned by lookup. */ 63 uint32_t key; /**< Key used to find value. */ 64 } entry; /**< For accessing each entry part. */ 65 }; 66 67 68 /** The four-byte key hash table structure. */ 69 struct rte_fbk_hash_table { 70 char name[RTE_FBK_HASH_NAMESIZE]; /**< Name of the hash. */ 71 uint32_t entries; /**< Total number of entries. */ 72 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */ 73 uint32_t used_entries; /**< How many entries are used. */ 74 uint32_t bucket_mask; /**< To find which bucket the key is in. */ 75 uint32_t bucket_shift; /**< Convert bucket to table offset. */ 76 rte_fbk_hash_fn hash_func; /**< The hash function. */ 77 uint32_t init_val; /**< For initialising hash function. */ 78 79 /** A flat table of all buckets. */ 80 union rte_fbk_hash_entry t[]; 81 }; 82 83 /** 84 * Find the offset into hash table of the bucket containing a particular key. 85 * 86 * @param ht 87 * Pointer to hash table. 88 * @param key 89 * Key to calculate bucket for. 90 * @return 91 * Offset into hash table. 92 */ 93 static inline uint32_t 94 rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key) 95 { 96 return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) << 97 ht->bucket_shift; 98 } 99 100 /** 101 * Add a key to an existing hash table with bucket id. 102 * This operation is not multi-thread safe 103 * and should only be called from one thread. 104 * 105 * @param ht 106 * Hash table to add the key to. 107 * @param key 108 * Key to add to the hash table. 109 * @param value 110 * Value to associate with key. 111 * @param bucket 112 * Bucket to associate with key. 113 * @return 114 * 0 if ok, or negative value on error. 115 */ 116 static inline int 117 rte_fbk_hash_add_key_with_bucket(struct rte_fbk_hash_table *ht, 118 uint32_t key, uint16_t value, uint32_t bucket) 119 { 120 /* 121 * The writing of a new value to the hash table is done as a single 122 * 64bit operation. This should help prevent individual entries being 123 * corrupted due to race conditions, but it's still possible to 124 * overwrite entries that have just been made valid. 125 */ 126 const uint64_t new_entry = ((uint64_t)(key) << 32) | 127 ((uint64_t)(value) << 16) | 128 1; /* 1 = is_entry bit. */ 129 uint32_t i; 130 131 for (i = 0; i < ht->entries_per_bucket; i++) { 132 /* Set entry if unused. */ 133 if (! ht->t[bucket + i].entry.is_entry) { 134 ht->t[bucket + i].whole_entry = new_entry; 135 ht->used_entries++; 136 return 0; 137 } 138 /* Change value if key already exists. */ 139 if (ht->t[bucket + i].entry.key == key) { 140 ht->t[bucket + i].entry.value = value; 141 return 0; 142 } 143 } 144 145 return -ENOSPC; /* No space in bucket. */ 146 } 147 148 /** 149 * Add a key to an existing hash table. This operation is not multi-thread safe 150 * and should only be called from one thread. 151 * 152 * @param ht 153 * Hash table to add the key to. 154 * @param key 155 * Key to add to the hash table. 156 * @param value 157 * Value to associate with key. 158 * @return 159 * 0 if ok, or negative value on error. 160 */ 161 static inline int 162 rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht, 163 uint32_t key, uint16_t value) 164 { 165 return rte_fbk_hash_add_key_with_bucket(ht, 166 key, value, rte_fbk_hash_get_bucket(ht, key)); 167 } 168 169 /** 170 * Remove a key with a given bucket id from an existing hash table. 171 * This operation is not multi-thread 172 * safe and should only be called from one thread. 173 * 174 * @param ht 175 * Hash table to remove the key from. 176 * @param key 177 * Key to remove from the hash table. 178 * @param bucket 179 * Bucket id associate with key. 180 * @return 181 * 0 if ok, or negative value on error. 182 */ 183 static inline int 184 rte_fbk_hash_delete_key_with_bucket(struct rte_fbk_hash_table *ht, 185 uint32_t key, uint32_t bucket) 186 { 187 uint32_t last_entry = ht->entries_per_bucket - 1; 188 uint32_t i, j; 189 190 for (i = 0; i < ht->entries_per_bucket; i++) { 191 if (ht->t[bucket + i].entry.key == key) { 192 /* Find last key in bucket. */ 193 for (j = ht->entries_per_bucket - 1; j > i; j-- ) { 194 if (! ht->t[bucket + j].entry.is_entry) { 195 last_entry = j - 1; 196 } 197 } 198 /* 199 * Move the last key to the deleted key's position, and 200 * delete the last key. lastEntry and i may be same but 201 * it doesn't matter. 202 */ 203 ht->t[bucket + i].whole_entry = 204 ht->t[bucket + last_entry].whole_entry; 205 ht->t[bucket + last_entry].whole_entry = 0; 206 207 ht->used_entries--; 208 return 0; 209 } 210 } 211 212 return -ENOENT; /* Key didn't exist. */ 213 } 214 215 /** 216 * Remove a key from an existing hash table. This operation is not multi-thread 217 * safe and should only be called from one thread. 218 * 219 * @param ht 220 * Hash table to remove the key from. 221 * @param key 222 * Key to remove from the hash table. 223 * @return 224 * 0 if ok, or negative value on error. 225 */ 226 static inline int 227 rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key) 228 { 229 return rte_fbk_hash_delete_key_with_bucket(ht, 230 key, rte_fbk_hash_get_bucket(ht, key)); 231 } 232 233 /** 234 * Find a key in the hash table with a given bucketid. 235 * This operation is multi-thread safe. 236 * 237 * @param ht 238 * Hash table to look in. 239 * @param key 240 * Key to find. 241 * @param bucket 242 * Bucket associate to the key. 243 * @return 244 * The value that was associated with the key, or negative value on error. 245 */ 246 static inline int 247 rte_fbk_hash_lookup_with_bucket(const struct rte_fbk_hash_table *ht, 248 uint32_t key, uint32_t bucket) 249 { 250 union rte_fbk_hash_entry current_entry; 251 uint32_t i; 252 253 for (i = 0; i < ht->entries_per_bucket; i++) { 254 /* Single read of entry, which should be atomic. */ 255 current_entry.whole_entry = ht->t[bucket + i].whole_entry; 256 if (! current_entry.entry.is_entry) { 257 return -ENOENT; /* Error once we hit an empty field. */ 258 } 259 if (current_entry.entry.key == key) { 260 return current_entry.entry.value; 261 } 262 } 263 return -ENOENT; /* Key didn't exist. */ 264 } 265 266 /** 267 * Find a key in the hash table. This operation is multi-thread safe. 268 * 269 * @param ht 270 * Hash table to look in. 271 * @param key 272 * Key to find. 273 * @return 274 * The value that was associated with the key, or negative value on error. 275 */ 276 static inline int 277 rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key) 278 { 279 return rte_fbk_hash_lookup_with_bucket(ht, 280 key, rte_fbk_hash_get_bucket(ht, key)); 281 } 282 283 /** 284 * Delete all entries in a hash table. This operation is not multi-thread 285 * safe and should only be called from one thread. 286 * 287 * @param ht 288 * Hash table to delete entries in. 289 */ 290 static inline void 291 rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht) 292 { 293 memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries); 294 ht->used_entries = 0; 295 } 296 297 /** 298 * Find what fraction of entries are being used. 299 * 300 * @param ht 301 * Hash table to find how many entries are being used in. 302 * @return 303 * Load factor of the hash table, or negative value on error. 304 */ 305 static inline double 306 rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht) 307 { 308 return (double)ht->used_entries / (double)ht->entries; 309 } 310 311 /** 312 * Performs a lookup for an existing hash table, and returns a pointer to 313 * the table if found. 314 * 315 * @param name 316 * Name of the hash table to find 317 * 318 * @return 319 * pointer to hash table structure or NULL on error with rte_errno 320 * set appropriately. Possible rte_errno values include: 321 * - ENOENT - required entry not available to return. 322 */ 323 struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name); 324 325 /** 326 * Create a new hash table for use with four byte keys. 327 * 328 * @param params 329 * Parameters used in creation of hash table. 330 * 331 * @return 332 * Pointer to hash table structure that is used in future hash table 333 * operations, or NULL on error with rte_errno set appropriately. 334 * Possible rte_errno error values include: 335 * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure 336 * - E_RTE_SECONDARY - function was called from a secondary process instance 337 * - EINVAL - invalid parameter value passed to function 338 * - ENOSPC - the maximum number of memzones has already been allocated 339 * - EEXIST - a memzone with the same name already exists 340 * - ENOMEM - no appropriate memory area found in which to create memzone 341 */ 342 struct rte_fbk_hash_table * \ 343 rte_fbk_hash_create(const struct rte_fbk_hash_params *params); 344 345 /** 346 * Free all memory used by a hash table. 347 * Has no effect on hash tables allocated in memory zones 348 * 349 * @param ht 350 * Hash table to deallocate. 351 */ 352 void rte_fbk_hash_free(struct rte_fbk_hash_table *ht); 353 354 #ifdef __cplusplus 355 } 356 #endif 357 358 #endif /* _RTE_FBK_HASH_H_ */ 359