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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>
51 #include <rte_hash_crc.h>
59 #ifndef RTE_FBK_HASH_FUNC_DEFAULT
60 /** Default four-byte key hash function if none is specified. */
61 #define RTE_FBK_HASH_FUNC_DEFAULT rte_hash_crc_4byte
64 #ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT
65 /** Initialising value used when calculating hash. */
66 #define RTE_FBK_HASH_INIT_VAL_DEFAULT 0xFFFFFFFF
69 /** The maximum number of entries in the hash table that is supported. */
70 #define RTE_FBK_HASH_ENTRIES_MAX (1 << 20)
72 /** The maximum number of entries in each bucket that is supported. */
73 #define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX 256
75 /** Maximum size of string for naming the hash. */
76 #define RTE_FBK_HASH_NAMESIZE 32
78 /** Type of function that can be used for calculating the hash value. */
79 typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val);
81 /** Parameters used when creating four-byte key hash table. */
82 struct rte_fbk_hash_params {
83 const char *name; /**< Name of the hash table. */
84 uint32_t entries; /**< Total number of entries. */
85 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */
86 int socket_id; /**< Socket to allocate memory on. */
87 rte_fbk_hash_fn hash_func; /**< The hash function. */
88 uint32_t init_val; /**< For initialising hash function. */
91 /** Individual entry in the four-byte key hash table. */
92 union rte_fbk_hash_entry {
93 uint64_t whole_entry; /**< For accessing entire entry. */
95 uint16_t is_entry; /**< Non-zero if entry is active. */
96 uint16_t value; /**< Value returned by lookup. */
97 uint32_t key; /**< Key used to find value. */
98 } entry; /**< For accessing each entry part. */
103 /** The four-byte key hash table structure. */
104 struct rte_fbk_hash_table {
105 TAILQ_ENTRY(rte_fbk_hash_table) next; /**< Linked list. */
107 char name[RTE_FBK_HASH_NAMESIZE]; /**< Name of the hash. */
108 uint32_t entries; /**< Total number of entries. */
109 uint32_t entries_per_bucket; /**< Number of entries in a bucket. */
110 uint32_t used_entries; /**< How many entries are used. */
111 uint32_t bucket_mask; /**< To find which bucket the key is in. */
112 uint32_t bucket_shift; /**< Convert bucket to table offset. */
113 rte_fbk_hash_fn hash_func; /**< The hash function. */
114 uint32_t init_val; /**< For initialising hash function. */
116 /** A flat table of all buckets. */
117 union rte_fbk_hash_entry t[0];
121 * Find the offset into hash table of the bucket containing a particular key.
124 * Pointer to hash table.
126 * Key to calculate bucket for.
128 * Offset into hash table.
130 static inline uint32_t
131 rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key)
133 return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) <<
139 * Add a key to an existing hash table. This operation is not multi-thread safe
140 * and should only be called from one thread.
143 * Hash table to add the key to.
145 * Key to add to the hash table.
147 * Value to associate with key.
149 * 0 if ok, or negative value on error.
152 rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht,
153 uint32_t key, uint16_t value)
156 * The writing of a new value to the hash table is done as a single
157 * 64bit operation. This should help prevent individual entries being
158 * corrupted due to race conditions, but it's still possible to
159 * overwrite entries that have just been made valid.
161 const uint64_t new_entry = ((uint64_t)(key) << 32) |
162 ((uint64_t)(value) << 16) |
163 1; /* 1 = is_entry bit. */
164 const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
167 for (i = 0; i < ht->entries_per_bucket; i++) {
168 /* Set entry if unused. */
169 if (! ht->t[bucket + i].entry.is_entry) {
170 ht->t[bucket + i].whole_entry = new_entry;
174 /* Change value if key already exists. */
175 if (ht->t[bucket + i].entry.key == key) {
176 ht->t[bucket + i].entry.value = value;
181 return -ENOSPC; /* No space in bucket. */
185 * Remove a key from an existing hash table. This operation is not multi-thread
186 * safe and should only be called from one thread.
189 * Hash table to remove the key from.
191 * Key to remove from the hash table.
193 * 0 if ok, or negative value on error.
196 rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key)
198 const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
199 uint32_t last_entry = ht->entries_per_bucket - 1;
202 for (i = 0; i < ht->entries_per_bucket; i++) {
203 if (ht->t[bucket + i].entry.key == key) {
204 /* Find last key in bucket. */
205 for (j = ht->entries_per_bucket - 1; j > i; j-- ) {
206 if (! ht->t[bucket + j].entry.is_entry) {
211 * Move the last key to the deleted key's position, and
212 * delete the last key. lastEntry and i may be same but
215 ht->t[bucket + i].whole_entry =
216 ht->t[bucket + last_entry].whole_entry;
217 ht->t[bucket + last_entry].whole_entry = 0;
224 return -ENOENT; /* Key didn't exist. */
228 * Find a key in the hash table. This operation is multi-thread safe.
231 * Hash table to look in.
235 * The value that was associated with the key, or negative value on error.
238 rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key)
240 const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
241 union rte_fbk_hash_entry current_entry;
244 for (i = 0; i < ht->entries_per_bucket; i++) {
245 /* Single read of entry, which should be atomic. */
246 current_entry.whole_entry = ht->t[bucket + i].whole_entry;
247 if (! current_entry.entry.is_entry) {
248 return -ENOENT; /* Error once we hit an empty field. */
250 if (current_entry.entry.key == key) {
251 return current_entry.entry.value;
254 return -ENOENT; /* Key didn't exist. */
258 * Delete all entries in a hash table. This operation is not multi-thread
259 * safe and should only be called from one thread.
262 * Hash table to delete entries in.
265 rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht)
267 memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries);
268 ht->used_entries = 0;
272 * Find what fraction of entries are being used.
275 * Hash table to find how many entries are being used in.
277 * Load factor of the hash table, or negative value on error.
280 rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht)
282 return (double)ht->used_entries / (double)ht->entries;
286 * Performs a lookup for an existing hash table, and returns a pointer to
287 * the table if found.
290 * Name of the hash table to find
293 * pointer to hash table structure or NULL on error with rte_errno
294 * set appropriately. Possible rte_errno values include:
295 * - ENOENT - required entry not available to return.
297 struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name);
300 * Create a new hash table for use with four byte keys.
303 * Parameters used in creation of hash table.
306 * Pointer to hash table structure that is used in future hash table
307 * operations, or NULL on error with rte_errno set appropriately.
308 * Possible rte_errno error values include:
309 * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
310 * - E_RTE_SECONDARY - function was called from a secondary process instance
311 * - E_RTE_NO_TAILQ - no tailq list could be got for the fbk hash table list
312 * - EINVAL - invalid parameter value passed to function
313 * - ENOSPC - the maximum number of memzones has already been allocated
314 * - EEXIST - a memzone with the same name already exists
315 * - ENOMEM - no appropriate memory area found in which to create memzone
317 struct rte_fbk_hash_table * \
318 rte_fbk_hash_create(const struct rte_fbk_hash_params *params);
321 * Free all memory used by a hash table.
322 * Has no effect on hash tables allocated in memory zones
325 * Hash table to deallocate.
327 void rte_fbk_hash_free(struct rte_fbk_hash_table *ht);
333 #endif /* _RTE_FBK_HASH_H_ */