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 #include <sys/queue.h> 21 22 #ifdef __cplusplus 23 extern "C" { 24 #endif 25 26 #include <string.h> 27 28 #include <rte_config.h> 29 #include <rte_hash_crc.h> 30 #include <rte_jhash.h> 31 32 #ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT 33 /** Initialising value used when calculating hash. */ 34 #define RTE_FBK_HASH_INIT_VAL_DEFAULT 0xFFFFFFFF 35 #endif 36 37 /** The maximum number of entries in the hash table that is supported. */ 38 #define RTE_FBK_HASH_ENTRIES_MAX (1 << 20) 39 40 /** The maximum number of entries in each bucket that is supported. */ 41 #define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX 256 42 43 /** Maximum size of string for naming the hash. */ 44 #define RTE_FBK_HASH_NAMESIZE 32 45 46 /** Type of function that can be used for calculating the hash value. */ 47 typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val); 48 49 /** Parameters used when creating four-byte key hash table. */ 50 struct rte_fbk_hash_params { 51 const char *name; /**< Name of the hash table. */ 52 uint32_t entries; /**< Total number of entries. */ 53 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */ 54 int socket_id; /**< Socket to allocate memory on. */ 55 rte_fbk_hash_fn hash_func; /**< The hash function. */ 56 uint32_t init_val; /**< For initialising hash function. */ 57 }; 58 59 /** Individual entry in the four-byte key hash table. */ 60 union rte_fbk_hash_entry { 61 uint64_t whole_entry; /**< For accessing entire entry. */ 62 struct { 63 uint16_t is_entry; /**< Non-zero if entry is active. */ 64 uint16_t value; /**< Value returned by lookup. */ 65 uint32_t key; /**< Key used to find value. */ 66 } entry; /**< For accessing each entry part. */ 67 }; 68 69 70 /** The four-byte key hash table structure. */ 71 struct rte_fbk_hash_table { 72 char name[RTE_FBK_HASH_NAMESIZE]; /**< Name of the hash. */ 73 uint32_t entries; /**< Total number of entries. */ 74 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */ 75 uint32_t used_entries; /**< How many entries are used. */ 76 uint32_t bucket_mask; /**< To find which bucket the key is in. */ 77 uint32_t bucket_shift; /**< Convert bucket to table offset. */ 78 rte_fbk_hash_fn hash_func; /**< The hash function. */ 79 uint32_t init_val; /**< For initialising hash function. */ 80 81 /** A flat table of all buckets. */ 82 union rte_fbk_hash_entry t[]; 83 }; 84 85 /** 86 * Find the offset into hash table of the bucket containing a particular key. 87 * 88 * @param ht 89 * Pointer to hash table. 90 * @param key 91 * Key to calculate bucket for. 92 * @return 93 * Offset into hash table. 94 */ 95 static inline uint32_t 96 rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key) 97 { 98 return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) << 99 ht->bucket_shift; 100 } 101 102 /** 103 * Add a key to an existing hash table with bucket id. 104 * This operation is not multi-thread safe 105 * and should only be called from one thread. 106 * 107 * @param ht 108 * Hash table to add the key to. 109 * @param key 110 * Key to add to the hash table. 111 * @param value 112 * Value to associate with key. 113 * @param bucket 114 * Bucket to associate with key. 115 * @return 116 * 0 if ok, or negative value on error. 117 */ 118 static inline int 119 rte_fbk_hash_add_key_with_bucket(struct rte_fbk_hash_table *ht, 120 uint32_t key, uint16_t value, uint32_t bucket) 121 { 122 /* 123 * The writing of a new value to the hash table is done as a single 124 * 64bit operation. This should help prevent individual entries being 125 * corrupted due to race conditions, but it's still possible to 126 * overwrite entries that have just been made valid. 127 */ 128 const uint64_t new_entry = ((uint64_t)(key) << 32) | 129 ((uint64_t)(value) << 16) | 130 1; /* 1 = is_entry bit. */ 131 uint32_t i; 132 133 for (i = 0; i < ht->entries_per_bucket; i++) { 134 /* Set entry if unused. */ 135 if (! ht->t[bucket + i].entry.is_entry) { 136 ht->t[bucket + i].whole_entry = new_entry; 137 ht->used_entries++; 138 return 0; 139 } 140 /* Change value if key already exists. */ 141 if (ht->t[bucket + i].entry.key == key) { 142 ht->t[bucket + i].entry.value = value; 143 return 0; 144 } 145 } 146 147 return -ENOSPC; /* No space in bucket. */ 148 } 149 150 /** 151 * Add a key to an existing hash table. This operation is not multi-thread safe 152 * and should only be called from one thread. 153 * 154 * @param ht 155 * Hash table to add the key to. 156 * @param key 157 * Key to add to the hash table. 158 * @param value 159 * Value to associate with key. 160 * @return 161 * 0 if ok, or negative value on error. 162 */ 163 static inline int 164 rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht, 165 uint32_t key, uint16_t value) 166 { 167 return rte_fbk_hash_add_key_with_bucket(ht, 168 key, value, rte_fbk_hash_get_bucket(ht, key)); 169 } 170 171 /** 172 * Remove a key with a given bucket id from an existing hash table. 173 * This operation is not multi-thread 174 * safe and should only be called from one thread. 175 * 176 * @param ht 177 * Hash table to remove the key from. 178 * @param key 179 * Key to remove from the hash table. 180 * @param bucket 181 * Bucket id associate with key. 182 * @return 183 * 0 if ok, or negative value on error. 184 */ 185 static inline int 186 rte_fbk_hash_delete_key_with_bucket(struct rte_fbk_hash_table *ht, 187 uint32_t key, uint32_t bucket) 188 { 189 uint32_t last_entry = ht->entries_per_bucket - 1; 190 uint32_t i, j; 191 192 for (i = 0; i < ht->entries_per_bucket; i++) { 193 if (ht->t[bucket + i].entry.key == key) { 194 /* Find last key in bucket. */ 195 for (j = ht->entries_per_bucket - 1; j > i; j-- ) { 196 if (! ht->t[bucket + j].entry.is_entry) { 197 last_entry = j - 1; 198 } 199 } 200 /* 201 * Move the last key to the deleted key's position, and 202 * delete the last key. lastEntry and i may be same but 203 * it doesn't matter. 204 */ 205 ht->t[bucket + i].whole_entry = 206 ht->t[bucket + last_entry].whole_entry; 207 ht->t[bucket + last_entry].whole_entry = 0; 208 209 ht->used_entries--; 210 return 0; 211 } 212 } 213 214 return -ENOENT; /* Key didn't exist. */ 215 } 216 217 /** 218 * Remove a key from an existing hash table. This operation is not multi-thread 219 * safe and should only be called from one thread. 220 * 221 * @param ht 222 * Hash table to remove the key from. 223 * @param key 224 * Key to remove from the hash table. 225 * @return 226 * 0 if ok, or negative value on error. 227 */ 228 static inline int 229 rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key) 230 { 231 return rte_fbk_hash_delete_key_with_bucket(ht, 232 key, rte_fbk_hash_get_bucket(ht, key)); 233 } 234 235 /** 236 * Find a key in the hash table with a given bucketid. 237 * This operation is multi-thread safe. 238 * 239 * @param ht 240 * Hash table to look in. 241 * @param key 242 * Key to find. 243 * @param bucket 244 * Bucket associate to the key. 245 * @return 246 * The value that was associated with the key, or negative value on error. 247 */ 248 static inline int 249 rte_fbk_hash_lookup_with_bucket(const struct rte_fbk_hash_table *ht, 250 uint32_t key, uint32_t bucket) 251 { 252 union rte_fbk_hash_entry current_entry; 253 uint32_t i; 254 255 for (i = 0; i < ht->entries_per_bucket; i++) { 256 /* Single read of entry, which should be atomic. */ 257 current_entry.whole_entry = ht->t[bucket + i].whole_entry; 258 if (! current_entry.entry.is_entry) { 259 return -ENOENT; /* Error once we hit an empty field. */ 260 } 261 if (current_entry.entry.key == key) { 262 return current_entry.entry.value; 263 } 264 } 265 return -ENOENT; /* Key didn't exist. */ 266 } 267 268 /** 269 * Find a key in the hash table. This operation is multi-thread safe. 270 * 271 * @param ht 272 * Hash table to look in. 273 * @param key 274 * Key to find. 275 * @return 276 * The value that was associated with the key, or negative value on error. 277 */ 278 static inline int 279 rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key) 280 { 281 return rte_fbk_hash_lookup_with_bucket(ht, 282 key, rte_fbk_hash_get_bucket(ht, key)); 283 } 284 285 /** 286 * Delete all entries in a hash table. This operation is not multi-thread 287 * safe and should only be called from one thread. 288 * 289 * @param ht 290 * Hash table to delete entries in. 291 */ 292 static inline void 293 rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht) 294 { 295 memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries); 296 ht->used_entries = 0; 297 } 298 299 /** 300 * Find what fraction of entries are being used. 301 * 302 * @param ht 303 * Hash table to find how many entries are being used in. 304 * @return 305 * Load factor of the hash table, or negative value on error. 306 */ 307 static inline double 308 rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht) 309 { 310 return (double)ht->used_entries / (double)ht->entries; 311 } 312 313 /** 314 * Performs a lookup for an existing hash table, and returns a pointer to 315 * the table if found. 316 * 317 * @param name 318 * Name of the hash table to find 319 * 320 * @return 321 * pointer to hash table structure or NULL on error with rte_errno 322 * set appropriately. Possible rte_errno values include: 323 * - ENOENT - required entry not available to return. 324 */ 325 struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name); 326 327 /** 328 * Create a new hash table for use with four byte keys. 329 * 330 * @param params 331 * Parameters used in creation of hash table. 332 * 333 * @return 334 * Pointer to hash table structure that is used in future hash table 335 * operations, or NULL on error with rte_errno set appropriately. 336 * Possible rte_errno error values include: 337 * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure 338 * - E_RTE_SECONDARY - function was called from a secondary process instance 339 * - EINVAL - invalid parameter value passed to function 340 * - ENOSPC - the maximum number of memzones has already been allocated 341 * - EEXIST - a memzone with the same name already exists 342 * - ENOMEM - no appropriate memory area found in which to create memzone 343 */ 344 struct rte_fbk_hash_table * \ 345 rte_fbk_hash_create(const struct rte_fbk_hash_params *params); 346 347 /** 348 * Free all memory used by a hash table. 349 * Has no effect on hash tables allocated in memory zones 350 * 351 * @param ht 352 * Hash table to deallocate. 353 */ 354 void rte_fbk_hash_free(struct rte_fbk_hash_table *ht); 355 356 #ifdef __cplusplus 357 } 358 #endif 359 360 #endif /* _RTE_FBK_HASH_H_ */ 361