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35 #ifndef _RTE_FBK_HASH_H_
36 #define _RTE_FBK_HASH_H_
41 * This is a hash table implementation for four byte keys (fbk).
43 * Note that the return value of the add function should always be checked as,
44 * if a bucket is full, the key is not added even if there is space in other
45 * buckets. This keeps the lookup function very simple and therefore fast.
50 #include <sys/queue.h>
58 #ifndef RTE_FBK_HASH_FUNC_DEFAULT
59 #ifdef RTE_MACHINE_CPUFLAG_SSE4_2
60 #include <rte_hash_crc.h>
61 /** Default four-byte key hash function if none is specified. */
62 #define RTE_FBK_HASH_FUNC_DEFAULT rte_hash_crc_4byte
64 #include <rte_jhash.h>
65 #define RTE_FBK_HASH_FUNC_DEFAULT rte_jhash_1word
69 #ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT
70 /** Initialising value used when calculating hash. */
71 #define RTE_FBK_HASH_INIT_VAL_DEFAULT 0xFFFFFFFF
74 /** The maximum number of entries in the hash table that is supported. */
75 #define RTE_FBK_HASH_ENTRIES_MAX (1 << 20)
77 /** The maximum number of entries in each bucket that is supported. */
78 #define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX 256
80 /** Maximum size of string for naming the hash. */
81 #define RTE_FBK_HASH_NAMESIZE 32
83 /** Type of function that can be used for calculating the hash value. */
84 typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val);
86 /** Parameters used when creating four-byte key hash table. */
87 struct rte_fbk_hash_params {
88 const char *name; /**< Name of the hash table. */
89 uint32_t entries; /**< Total number of entries. */
90 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */
91 int socket_id; /**< Socket to allocate memory on. */
92 rte_fbk_hash_fn hash_func; /**< The hash function. */
93 uint32_t init_val; /**< For initialising hash function. */
96 /** Individual entry in the four-byte key hash table. */
97 union rte_fbk_hash_entry {
98 uint64_t whole_entry; /**< For accessing entire entry. */
100 uint16_t is_entry; /**< Non-zero if entry is active. */
101 uint16_t value; /**< Value returned by lookup. */
102 uint32_t key; /**< Key used to find value. */
103 } entry; /**< For accessing each entry part. */
108 /** The four-byte key hash table structure. */
109 struct rte_fbk_hash_table {
110 TAILQ_ENTRY(rte_fbk_hash_table) next; /**< Linked list. */
112 char name[RTE_FBK_HASH_NAMESIZE]; /**< Name of the hash. */
113 uint32_t entries; /**< Total number of entries. */
114 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */
115 uint32_t used_entries; /**< How many entries are used. */
116 uint32_t bucket_mask; /**< To find which bucket the key is in. */
117 uint32_t bucket_shift; /**< Convert bucket to table offset. */
118 rte_fbk_hash_fn hash_func; /**< The hash function. */
119 uint32_t init_val; /**< For initialising hash function. */
121 /** A flat table of all buckets. */
122 union rte_fbk_hash_entry t[0];
126 * Find the offset into hash table of the bucket containing a particular key.
129 * Pointer to hash table.
131 * Key to calculate bucket for.
133 * Offset into hash table.
135 static inline uint32_t
136 rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key)
138 return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) <<
144 * Add a key to an existing hash table. This operation is not multi-thread safe
145 * and should only be called from one thread.
148 * Hash table to add the key to.
150 * Key to add to the hash table.
152 * Value to associate with key.
154 * 0 if ok, or negative value on error.
157 rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht,
158 uint32_t key, uint16_t value)
161 * The writing of a new value to the hash table is done as a single
162 * 64bit operation. This should help prevent individual entries being
163 * corrupted due to race conditions, but it's still possible to
164 * overwrite entries that have just been made valid.
166 const uint64_t new_entry = ((uint64_t)(key) << 32) |
167 ((uint64_t)(value) << 16) |
168 1; /* 1 = is_entry bit. */
169 const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
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 * Remove a key from an existing hash table. This operation is not multi-thread
191 * safe and should only be called from one thread.
194 * Hash table to remove the key from.
196 * Key to remove from the hash table.
198 * 0 if ok, or negative value on error.
201 rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key)
203 const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
204 uint32_t last_entry = ht->entries_per_bucket - 1;
207 for (i = 0; i < ht->entries_per_bucket; i++) {
208 if (ht->t[bucket + i].entry.key == key) {
209 /* Find last key in bucket. */
210 for (j = ht->entries_per_bucket - 1; j > i; j-- ) {
211 if (! ht->t[bucket + j].entry.is_entry) {
216 * Move the last key to the deleted key's position, and
217 * delete the last key. lastEntry and i may be same but
220 ht->t[bucket + i].whole_entry =
221 ht->t[bucket + last_entry].whole_entry;
222 ht->t[bucket + last_entry].whole_entry = 0;
229 return -ENOENT; /* Key didn't exist. */
233 * Find a key in the hash table. This operation is multi-thread safe.
236 * Hash table to look in.
240 * The value that was associated with the key, or negative value on error.
243 rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key)
245 const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
246 union rte_fbk_hash_entry current_entry;
249 for (i = 0; i < ht->entries_per_bucket; i++) {
250 /* Single read of entry, which should be atomic. */
251 current_entry.whole_entry = ht->t[bucket + i].whole_entry;
252 if (! current_entry.entry.is_entry) {
253 return -ENOENT; /* Error once we hit an empty field. */
255 if (current_entry.entry.key == key) {
256 return current_entry.entry.value;
259 return -ENOENT; /* Key didn't exist. */
263 * Delete all entries in a hash table. This operation is not multi-thread
264 * safe and should only be called from one thread.
267 * Hash table to delete entries in.
270 rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht)
272 memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries);
273 ht->used_entries = 0;
277 * Find what fraction of entries are being used.
280 * Hash table to find how many entries are being used in.
282 * Load factor of the hash table, or negative value on error.
285 rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht)
287 return (double)ht->used_entries / (double)ht->entries;
291 * Performs a lookup for an existing hash table, and returns a pointer to
292 * the table if found.
295 * Name of the hash table to find
298 * pointer to hash table structure or NULL on error with rte_errno
299 * set appropriately. Possible rte_errno values include:
300 * - ENOENT - required entry not available to return.
302 struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name);
305 * Create a new hash table for use with four byte keys.
308 * Parameters used in creation of hash table.
311 * Pointer to hash table structure that is used in future hash table
312 * operations, or NULL on error with rte_errno set appropriately.
313 * Possible rte_errno error values include:
314 * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
315 * - E_RTE_SECONDARY - function was called from a secondary process instance
316 * - E_RTE_NO_TAILQ - no tailq list could be got for the fbk hash table list
317 * - EINVAL - invalid parameter value passed to function
318 * - ENOSPC - the maximum number of memzones has already been allocated
319 * - EEXIST - a memzone with the same name already exists
320 * - ENOMEM - no appropriate memory area found in which to create memzone
322 struct rte_fbk_hash_table * \
323 rte_fbk_hash_create(const struct rte_fbk_hash_params *params);
326 * Free all memory used by a hash table.
327 * Has no effect on hash tables allocated in memory zones
330 * Hash table to deallocate.
332 void rte_fbk_hash_free(struct rte_fbk_hash_table *ht);
338 #endif /* _RTE_FBK_HASH_H_ */