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 #ifdef __cplusplus 22 extern "C" { 23 #endif 24 25 #include <string.h> 26 27 #include <rte_config.h> 28 #include <rte_hash_crc.h> 29 #include <rte_jhash.h> 30 31 #ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT 32 /** Initialising value used when calculating hash. */ 33 #define RTE_FBK_HASH_INIT_VAL_DEFAULT 0xFFFFFFFF 34 #endif 35 36 /** The maximum number of entries in the hash table that is supported. */ 37 #define RTE_FBK_HASH_ENTRIES_MAX (1 << 20) 38 39 /** The maximum number of entries in each bucket that is supported. */ 40 #define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX 256 41 42 /** Maximum size of string for naming the hash. */ 43 #define RTE_FBK_HASH_NAMESIZE 32 44 45 /** Type of function that can be used for calculating the hash value. */ 46 typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val); 47 48 /** Parameters used when creating four-byte key hash table. */ 49 struct rte_fbk_hash_params { 50 const char *name; /**< Name of the hash table. */ 51 uint32_t entries; /**< Total number of entries. */ 52 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */ 53 int socket_id; /**< Socket to allocate memory on. */ 54 rte_fbk_hash_fn hash_func; /**< The hash function. */ 55 uint32_t init_val; /**< For initialising hash function. */ 56 }; 57 58 /** Individual entry in the four-byte key hash table. */ 59 union rte_fbk_hash_entry { 60 uint64_t whole_entry; /**< For accessing entire entry. */ 61 struct { 62 uint16_t is_entry; /**< Non-zero if entry is active. */ 63 uint16_t value; /**< Value returned by lookup. */ 64 uint32_t key; /**< Key used to find value. */ 65 } entry; /**< For accessing each entry part. */ 66 }; 67 68 69 /** The four-byte key hash table structure. */ 70 struct rte_fbk_hash_table { 71 char name[RTE_FBK_HASH_NAMESIZE]; /**< Name of the hash. */ 72 uint32_t entries; /**< Total number of entries. */ 73 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */ 74 uint32_t used_entries; /**< How many entries are used. */ 75 uint32_t bucket_mask; /**< To find which bucket the key is in. */ 76 uint32_t bucket_shift; /**< Convert bucket to table offset. */ 77 rte_fbk_hash_fn hash_func; /**< The hash function. */ 78 uint32_t init_val; /**< For initialising hash function. */ 79 80 /** A flat table of all buckets. */ 81 union rte_fbk_hash_entry t[]; 82 }; 83 84 /** 85 * Find the offset into hash table of the bucket containing a particular key. 86 * 87 * @param ht 88 * Pointer to hash table. 89 * @param key 90 * Key to calculate bucket for. 91 * @return 92 * Offset into hash table. 93 */ 94 static inline uint32_t 95 rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key) 96 { 97 return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) << 98 ht->bucket_shift; 99 } 100 101 /** 102 * Add a key to an existing hash table with bucket id. 103 * This operation is not multi-thread safe 104 * and should only be called from one thread. 105 * 106 * @param ht 107 * Hash table to add the key to. 108 * @param key 109 * Key to add to the hash table. 110 * @param value 111 * Value to associate with key. 112 * @param bucket 113 * Bucket to associate with key. 114 * @return 115 * 0 if ok, or negative value on error. 116 */ 117 static inline int 118 rte_fbk_hash_add_key_with_bucket(struct rte_fbk_hash_table *ht, 119 uint32_t key, uint16_t value, uint32_t bucket) 120 { 121 /* 122 * The writing of a new value to the hash table is done as a single 123 * 64bit operation. This should help prevent individual entries being 124 * corrupted due to race conditions, but it's still possible to 125 * overwrite entries that have just been made valid. 126 */ 127 const uint64_t new_entry = ((uint64_t)(key) << 32) | 128 ((uint64_t)(value) << 16) | 129 1; /* 1 = is_entry bit. */ 130 uint32_t i; 131 132 for (i = 0; i < ht->entries_per_bucket; i++) { 133 /* Set entry if unused. */ 134 if (! ht->t[bucket + i].entry.is_entry) { 135 ht->t[bucket + i].whole_entry = new_entry; 136 ht->used_entries++; 137 return 0; 138 } 139 /* Change value if key already exists. */ 140 if (ht->t[bucket + i].entry.key == key) { 141 ht->t[bucket + i].entry.value = value; 142 return 0; 143 } 144 } 145 146 return -ENOSPC; /* No space in bucket. */ 147 } 148 149 /** 150 * Add a key to an existing hash table. This operation is not multi-thread safe 151 * and should only be called from one thread. 152 * 153 * @param ht 154 * Hash table to add the key to. 155 * @param key 156 * Key to add to the hash table. 157 * @param value 158 * Value to associate with key. 159 * @return 160 * 0 if ok, or negative value on error. 161 */ 162 static inline int 163 rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht, 164 uint32_t key, uint16_t value) 165 { 166 return rte_fbk_hash_add_key_with_bucket(ht, 167 key, value, rte_fbk_hash_get_bucket(ht, key)); 168 } 169 170 /** 171 * Remove a key with a given bucket id from an existing hash table. 172 * This operation is not multi-thread 173 * safe and should only be called from one thread. 174 * 175 * @param ht 176 * Hash table to remove the key from. 177 * @param key 178 * Key to remove from the hash table. 179 * @param bucket 180 * Bucket id associate with key. 181 * @return 182 * 0 if ok, or negative value on error. 183 */ 184 static inline int 185 rte_fbk_hash_delete_key_with_bucket(struct rte_fbk_hash_table *ht, 186 uint32_t key, uint32_t bucket) 187 { 188 uint32_t last_entry = ht->entries_per_bucket - 1; 189 uint32_t i, j; 190 191 for (i = 0; i < ht->entries_per_bucket; i++) { 192 if (ht->t[bucket + i].entry.key == key) { 193 /* Find last key in bucket. */ 194 for (j = ht->entries_per_bucket - 1; j > i; j-- ) { 195 if (! ht->t[bucket + j].entry.is_entry) { 196 last_entry = j - 1; 197 } 198 } 199 /* 200 * Move the last key to the deleted key's position, and 201 * delete the last key. lastEntry and i may be same but 202 * it doesn't matter. 203 */ 204 ht->t[bucket + i].whole_entry = 205 ht->t[bucket + last_entry].whole_entry; 206 ht->t[bucket + last_entry].whole_entry = 0; 207 208 ht->used_entries--; 209 return 0; 210 } 211 } 212 213 return -ENOENT; /* Key didn't exist. */ 214 } 215 216 /** 217 * Remove a key from an existing hash table. This operation is not multi-thread 218 * safe and should only be called from one thread. 219 * 220 * @param ht 221 * Hash table to remove the key from. 222 * @param key 223 * Key to remove from the hash table. 224 * @return 225 * 0 if ok, or negative value on error. 226 */ 227 static inline int 228 rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key) 229 { 230 return rte_fbk_hash_delete_key_with_bucket(ht, 231 key, rte_fbk_hash_get_bucket(ht, key)); 232 } 233 234 /** 235 * Find a key in the hash table with a given bucketid. 236 * This operation is multi-thread safe. 237 * 238 * @param ht 239 * Hash table to look in. 240 * @param key 241 * Key to find. 242 * @param bucket 243 * Bucket associate to the key. 244 * @return 245 * The value that was associated with the key, or negative value on error. 246 */ 247 static inline int 248 rte_fbk_hash_lookup_with_bucket(const struct rte_fbk_hash_table *ht, 249 uint32_t key, uint32_t bucket) 250 { 251 union rte_fbk_hash_entry current_entry; 252 uint32_t i; 253 254 for (i = 0; i < ht->entries_per_bucket; i++) { 255 /* Single read of entry, which should be atomic. */ 256 current_entry.whole_entry = ht->t[bucket + i].whole_entry; 257 if (! current_entry.entry.is_entry) { 258 return -ENOENT; /* Error once we hit an empty field. */ 259 } 260 if (current_entry.entry.key == key) { 261 return current_entry.entry.value; 262 } 263 } 264 return -ENOENT; /* Key didn't exist. */ 265 } 266 267 /** 268 * Find a key in the hash table. This operation is multi-thread safe. 269 * 270 * @param ht 271 * Hash table to look in. 272 * @param key 273 * Key to find. 274 * @return 275 * The value that was associated with the key, or negative value on error. 276 */ 277 static inline int 278 rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key) 279 { 280 return rte_fbk_hash_lookup_with_bucket(ht, 281 key, rte_fbk_hash_get_bucket(ht, key)); 282 } 283 284 /** 285 * Delete all entries in a hash table. This operation is not multi-thread 286 * safe and should only be called from one thread. 287 * 288 * @param ht 289 * Hash table to delete entries in. 290 */ 291 static inline void 292 rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht) 293 { 294 memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries); 295 ht->used_entries = 0; 296 } 297 298 /** 299 * Find what fraction of entries are being used. 300 * 301 * @param ht 302 * Hash table to find how many entries are being used in. 303 * @return 304 * Load factor of the hash table, or negative value on error. 305 */ 306 static inline double 307 rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht) 308 { 309 return (double)ht->used_entries / (double)ht->entries; 310 } 311 312 /** 313 * Performs a lookup for an existing hash table, and returns a pointer to 314 * the table if found. 315 * 316 * @param name 317 * Name of the hash table to find 318 * 319 * @return 320 * pointer to hash table structure or NULL on error with rte_errno 321 * set appropriately. Possible rte_errno values include: 322 * - ENOENT - required entry not available to return. 323 */ 324 struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name); 325 326 /** 327 * Create a new hash table for use with four byte keys. 328 * 329 * @param params 330 * Parameters used in creation of hash table. 331 * 332 * @return 333 * Pointer to hash table structure that is used in future hash table 334 * operations, or NULL on error with rte_errno set appropriately. 335 * Possible rte_errno error values include: 336 * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure 337 * - E_RTE_SECONDARY - function was called from a secondary process instance 338 * - EINVAL - invalid parameter value passed to function 339 * - ENOSPC - the maximum number of memzones has already been allocated 340 * - EEXIST - a memzone with the same name already exists 341 * - ENOMEM - no appropriate memory area found in which to create memzone 342 */ 343 struct rte_fbk_hash_table * \ 344 rte_fbk_hash_create(const struct rte_fbk_hash_params *params); 345 346 /** 347 * Free all memory used by a hash table. 348 * Has no effect on hash tables allocated in memory zones 349 * 350 * @param ht 351 * Hash table to deallocate. 352 */ 353 void rte_fbk_hash_free(struct rte_fbk_hash_table *ht); 354 355 #ifdef __cplusplus 356 } 357 #endif 358 359 #endif /* _RTE_FBK_HASH_H_ */ 360