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34 #ifndef _RTE_FBK_HASH_H_
35 #define _RTE_FBK_HASH_H_
40 * This is a hash table implementation for four byte keys (fbk).
42 * Note that the return value of the add function should always be checked as,
43 * if a bucket is full, the key is not added even if there is space in other
44 * buckets. This keeps the lookup function very simple and therefore fast.
49 #include <sys/queue.h>
57 #ifndef RTE_FBK_HASH_FUNC_DEFAULT
58 #ifdef RTE_MACHINE_CPUFLAG_SSE4_2
59 #include <rte_hash_crc.h>
60 /** Default four-byte key hash function if none is specified. */
61 #define RTE_FBK_HASH_FUNC_DEFAULT rte_hash_crc_4byte
63 #include <rte_jhash.h>
64 #define RTE_FBK_HASH_FUNC_DEFAULT rte_jhash_1word
68 #ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT
69 /** Initialising value used when calculating hash. */
70 #define RTE_FBK_HASH_INIT_VAL_DEFAULT 0xFFFFFFFF
73 /** The maximum number of entries in the hash table that is supported. */
74 #define RTE_FBK_HASH_ENTRIES_MAX (1 << 20)
76 /** The maximum number of entries in each bucket that is supported. */
77 #define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX 256
79 /** Maximum size of string for naming the hash. */
80 #define RTE_FBK_HASH_NAMESIZE 32
82 /** Type of function that can be used for calculating the hash value. */
83 typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val);
85 /** Parameters used when creating four-byte key hash table. */
86 struct rte_fbk_hash_params {
87 const char *name; /**< Name of the hash table. */
88 uint32_t entries; /**< Total number of entries. */
89 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */
90 int socket_id; /**< Socket to allocate memory on. */
91 rte_fbk_hash_fn hash_func; /**< The hash function. */
92 uint32_t init_val; /**< For initialising hash function. */
95 /** Individual entry in the four-byte key hash table. */
96 union rte_fbk_hash_entry {
97 uint64_t whole_entry; /**< For accessing entire entry. */
99 uint16_t is_entry; /**< Non-zero if entry is active. */
100 uint16_t value; /**< Value returned by lookup. */
101 uint32_t key; /**< Key used to find value. */
102 } entry; /**< For accessing each entry part. */
107 /** The four-byte key hash table structure. */
108 struct rte_fbk_hash_table {
109 TAILQ_ENTRY(rte_fbk_hash_table) next; /**< Linked list. */
111 char name[RTE_FBK_HASH_NAMESIZE]; /**< Name of the hash. */
112 uint32_t entries; /**< Total number of entries. */
113 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */
114 uint32_t used_entries; /**< How many entries are used. */
115 uint32_t bucket_mask; /**< To find which bucket the key is in. */
116 uint32_t bucket_shift; /**< Convert bucket to table offset. */
117 rte_fbk_hash_fn hash_func; /**< The hash function. */
118 uint32_t init_val; /**< For initialising hash function. */
120 /** A flat table of all buckets. */
121 union rte_fbk_hash_entry t[0];
125 * Find the offset into hash table of the bucket containing a particular key.
128 * Pointer to hash table.
130 * Key to calculate bucket for.
132 * Offset into hash table.
134 static inline uint32_t
135 rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key)
137 return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) <<
142 * Add a key to an existing hash table with bucket id.
143 * This operation is not multi-thread safe
144 * and should only be called from one thread.
147 * Hash table to add the key to.
149 * Key to add to the hash table.
151 * Value to associate with key.
153 * Bucket to associate with key.
155 * 0 if ok, or negative value on error.
158 rte_fbk_hash_add_key_with_bucket(struct rte_fbk_hash_table *ht,
159 uint32_t key, uint16_t value, uint32_t bucket)
162 * The writing of a new value to the hash table is done as a single
163 * 64bit operation. This should help prevent individual entries being
164 * corrupted due to race conditions, but it's still possible to
165 * overwrite entries that have just been made valid.
167 const uint64_t new_entry = ((uint64_t)(key) << 32) |
168 ((uint64_t)(value) << 16) |
169 1; /* 1 = is_entry bit. */
172 for (i = 0; i < ht->entries_per_bucket; i++) {
173 /* Set entry if unused. */
174 if (! ht->t[bucket + i].entry.is_entry) {
175 ht->t[bucket + i].whole_entry = new_entry;
179 /* Change value if key already exists. */
180 if (ht->t[bucket + i].entry.key == key) {
181 ht->t[bucket + i].entry.value = value;
186 return -ENOSPC; /* No space in bucket. */
190 * Add a key to an existing hash table. This operation is not multi-thread safe
191 * and should only be called from one thread.
194 * Hash table to add the key to.
196 * Key to add to the hash table.
198 * Value to associate with key.
200 * 0 if ok, or negative value on error.
203 rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht,
204 uint32_t key, uint16_t value)
206 return rte_fbk_hash_add_key_with_bucket(ht,
207 key, value, rte_fbk_hash_get_bucket(ht, key));
211 * Remove a key with a given bucket id from an existing hash table.
212 * This operation is not multi-thread
213 * safe and should only be called from one thread.
216 * Hash table to remove the key from.
218 * Key to remove from the hash table.
220 * Bucket id associate with key.
222 * 0 if ok, or negative value on error.
225 rte_fbk_hash_delete_key_with_bucket(struct rte_fbk_hash_table *ht,
226 uint32_t key, uint32_t bucket)
228 uint32_t last_entry = ht->entries_per_bucket - 1;
231 for (i = 0; i < ht->entries_per_bucket; i++) {
232 if (ht->t[bucket + i].entry.key == key) {
233 /* Find last key in bucket. */
234 for (j = ht->entries_per_bucket - 1; j > i; j-- ) {
235 if (! ht->t[bucket + j].entry.is_entry) {
240 * Move the last key to the deleted key's position, and
241 * delete the last key. lastEntry and i may be same but
244 ht->t[bucket + i].whole_entry =
245 ht->t[bucket + last_entry].whole_entry;
246 ht->t[bucket + last_entry].whole_entry = 0;
253 return -ENOENT; /* Key didn't exist. */
257 * Remove a key from an existing hash table. This operation is not multi-thread
258 * safe and should only be called from one thread.
261 * Hash table to remove the key from.
263 * Key to remove from the hash table.
265 * 0 if ok, or negative value on error.
268 rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key)
270 return rte_fbk_hash_delete_key_with_bucket(ht,
271 key, rte_fbk_hash_get_bucket(ht, key));
275 * Find a key in the hash table with a given bucketid.
276 * This operation is multi-thread safe.
279 * Hash table to look in.
283 * Bucket associate to the key.
285 * The value that was associated with the key, or negative value on error.
288 rte_fbk_hash_lookup_with_bucket(const struct rte_fbk_hash_table *ht,
289 uint32_t key, uint32_t bucket)
291 union rte_fbk_hash_entry current_entry;
294 for (i = 0; i < ht->entries_per_bucket; i++) {
295 /* Single read of entry, which should be atomic. */
296 current_entry.whole_entry = ht->t[bucket + i].whole_entry;
297 if (! current_entry.entry.is_entry) {
298 return -ENOENT; /* Error once we hit an empty field. */
300 if (current_entry.entry.key == key) {
301 return current_entry.entry.value;
304 return -ENOENT; /* Key didn't exist. */
308 * Find a key in the hash table. This operation is multi-thread safe.
311 * Hash table to look in.
315 * The value that was associated with the key, or negative value on error.
318 rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key)
320 return rte_fbk_hash_lookup_with_bucket(ht,
321 key, rte_fbk_hash_get_bucket(ht, key));
325 * Delete all entries in a hash table. This operation is not multi-thread
326 * safe and should only be called from one thread.
329 * Hash table to delete entries in.
332 rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht)
334 memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries);
335 ht->used_entries = 0;
339 * Find what fraction of entries are being used.
342 * Hash table to find how many entries are being used in.
344 * Load factor of the hash table, or negative value on error.
347 rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht)
349 return (double)ht->used_entries / (double)ht->entries;
353 * Performs a lookup for an existing hash table, and returns a pointer to
354 * the table if found.
357 * Name of the hash table to find
360 * pointer to hash table structure or NULL on error with rte_errno
361 * set appropriately. Possible rte_errno values include:
362 * - ENOENT - required entry not available to return.
364 struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name);
367 * Create a new hash table for use with four byte keys.
370 * Parameters used in creation of hash table.
373 * Pointer to hash table structure that is used in future hash table
374 * operations, or NULL on error with rte_errno set appropriately.
375 * Possible rte_errno error values include:
376 * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
377 * - E_RTE_SECONDARY - function was called from a secondary process instance
378 * - E_RTE_NO_TAILQ - no tailq list could be got for the fbk hash table list
379 * - EINVAL - invalid parameter value passed to function
380 * - ENOSPC - the maximum number of memzones has already been allocated
381 * - EEXIST - a memzone with the same name already exists
382 * - ENOMEM - no appropriate memory area found in which to create memzone
384 struct rte_fbk_hash_table * \
385 rte_fbk_hash_create(const struct rte_fbk_hash_params *params);
388 * Free all memory used by a hash table.
389 * Has no effect on hash tables allocated in memory zones
392 * Hash table to deallocate.
394 void rte_fbk_hash_free(struct rte_fbk_hash_table *ht);
400 #endif /* _RTE_FBK_HASH_H_ */