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/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2010-2017 Intel Corporation
*/
#ifndef __INCLUDE_RTE_TABLE_HASH_H__
#define __INCLUDE_RTE_TABLE_HASH_H__
#ifdef __cplusplus
extern "C" {
#endif
/**
* @file
* RTE Table Hash
*
* These tables use the exact match criterion to uniquely associate data to
* lookup keys.
*
* Hash table types:
* 1. Entry add strategy on bucket full:
* a. Least Recently Used (LRU): One of the existing keys in the bucket is
* deleted and the new key is added in its place. The number of keys in
* each bucket never grows bigger than 4. The logic to pick the key to
* be dropped from the bucket is LRU. The hash table lookup operation
* maintains the order in which the keys in the same bucket are hit, so
* every time a key is hit, it becomes the new Most Recently Used (MRU)
* key, i.e. the most unlikely candidate for drop. When a key is added
* to the bucket, it also becomes the new MRU key. When a key needs to
* be picked and dropped, the most likely candidate for drop, i.e. the
* current LRU key, is always picked. The LRU logic requires maintaining
* specific data structures per each bucket. Use-cases: flow cache, etc.
* b. Extendable bucket (ext): The bucket is extended with space for 4 more
* keys. This is done by allocating additional memory at table init time,
* which is used to create a pool of free keys (the size of this pool is
* configurable and always a multiple of 4). On key add operation, the
* allocation of a group of 4 keys only happens successfully within the
* limit of free keys, otherwise the key add operation fails. On key
* delete operation, a group of 4 keys is freed back to the pool of free
* keys when the key to be deleted is the only key that was used within
* its group of 4 keys at that time. On key lookup operation, if the
* current bucket is in extended state and a match is not found in the
* first group of 4 keys, the search continues beyond the first group of
* 4 keys, potentially until all keys in this bucket are examined. The
* extendable bucket logic requires maintaining specific data structures
* per table and per each bucket. Use-cases: flow table, etc.
* 2. Key size:
* a. Configurable key size
* b. Single key size (8-byte, 16-byte or 32-byte key size)
*
***/
#include <stdint.h>
#include "rte_table.h"
/** Hash function */
typedef uint64_t (*rte_table_hash_op_hash)(
void *key,
void *key_mask,
uint32_t key_size,
uint64_t seed);
/** Hash table parameters */
struct rte_table_hash_params {
/** Name */
const char *name;
/** Key size (number of bytes) */
uint32_t key_size;
/** Byte offset within packet meta-data where the key is located */
uint32_t key_offset;
/** Key mask */
uint8_t *key_mask;
/** Number of keys */
uint32_t n_keys;
/** Number of buckets */
uint32_t n_buckets;
/** Hash function */
rte_table_hash_op_hash f_hash;
/** Seed value for the hash function */
uint64_t seed;
};
/** Extendable bucket hash table operations */
extern struct rte_table_ops rte_table_hash_ext_ops;
extern struct rte_table_ops rte_table_hash_key8_ext_ops;
extern struct rte_table_ops rte_table_hash_key16_ext_ops;
extern struct rte_table_ops rte_table_hash_key32_ext_ops;
/** LRU hash table operations */
extern struct rte_table_ops rte_table_hash_lru_ops;
extern struct rte_table_ops rte_table_hash_key8_lru_ops;
extern struct rte_table_ops rte_table_hash_key16_lru_ops;
extern struct rte_table_ops rte_table_hash_key32_lru_ops;
#ifdef __cplusplus
}
#endif
#endif
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