339 lines
10 KiB
C
339 lines
10 KiB
C
/*-
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* BSD LICENSE
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*
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* Copyright(c) 2010-2013 Intel Corporation. All rights reserved.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* * Neither the name of Intel Corporation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#ifndef _RTE_FBK_HASH_H_
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#define _RTE_FBK_HASH_H_
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/**
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* @file
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*
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* This is a hash table implementation for four byte keys (fbk).
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*
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* Note that the return value of the add function should always be checked as,
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* if a bucket is full, the key is not added even if there is space in other
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* buckets. This keeps the lookup function very simple and therefore fast.
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*/
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#include <stdint.h>
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#include <errno.h>
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#include <sys/queue.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <string.h>
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#ifndef RTE_FBK_HASH_FUNC_DEFAULT
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#ifdef RTE_MACHINE_CPUFLAG_SSE4_2
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#include <rte_hash_crc.h>
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/** Default four-byte key hash function if none is specified. */
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#define RTE_FBK_HASH_FUNC_DEFAULT rte_hash_crc_4byte
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#else
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#include <rte_jhash.h>
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#define RTE_FBK_HASH_FUNC_DEFAULT rte_jhash_1word
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#endif
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#endif
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#ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT
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/** Initialising value used when calculating hash. */
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#define RTE_FBK_HASH_INIT_VAL_DEFAULT 0xFFFFFFFF
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#endif
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/** The maximum number of entries in the hash table that is supported. */
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#define RTE_FBK_HASH_ENTRIES_MAX (1 << 20)
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/** The maximum number of entries in each bucket that is supported. */
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#define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX 256
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/** Maximum size of string for naming the hash. */
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#define RTE_FBK_HASH_NAMESIZE 32
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/** Type of function that can be used for calculating the hash value. */
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typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val);
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/** Parameters used when creating four-byte key hash table. */
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struct rte_fbk_hash_params {
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const char *name; /**< Name of the hash table. */
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uint32_t entries; /**< Total number of entries. */
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uint32_t entries_per_bucket; /**< Number of entries in a bucket. */
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int socket_id; /**< Socket to allocate memory on. */
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rte_fbk_hash_fn hash_func; /**< The hash function. */
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uint32_t init_val; /**< For initialising hash function. */
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};
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/** Individual entry in the four-byte key hash table. */
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union rte_fbk_hash_entry {
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uint64_t whole_entry; /**< For accessing entire entry. */
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struct {
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uint16_t is_entry; /**< Non-zero if entry is active. */
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uint16_t value; /**< Value returned by lookup. */
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uint32_t key; /**< Key used to find value. */
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} entry; /**< For accessing each entry part. */
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};
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/** The four-byte key hash table structure. */
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struct rte_fbk_hash_table {
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TAILQ_ENTRY(rte_fbk_hash_table) next; /**< Linked list. */
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char name[RTE_FBK_HASH_NAMESIZE]; /**< Name of the hash. */
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uint32_t entries; /**< Total number of entries. */
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uint32_t entries_per_bucket; /**< Number of entries in a bucket. */
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uint32_t used_entries; /**< How many entries are used. */
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uint32_t bucket_mask; /**< To find which bucket the key is in. */
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uint32_t bucket_shift; /**< Convert bucket to table offset. */
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rte_fbk_hash_fn hash_func; /**< The hash function. */
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uint32_t init_val; /**< For initialising hash function. */
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/** A flat table of all buckets. */
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union rte_fbk_hash_entry t[0];
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};
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/**
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* Find the offset into hash table of the bucket containing a particular key.
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*
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* @param ht
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* Pointer to hash table.
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* @param key
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* Key to calculate bucket for.
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* @return
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* Offset into hash table.
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*/
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static inline uint32_t
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rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key)
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{
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return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) <<
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ht->bucket_shift;
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}
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/**
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* Add a key to an existing hash table. This operation is not multi-thread safe
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* and should only be called from one thread.
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*
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* @param ht
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* Hash table to add the key to.
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* @param key
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* Key to add to the hash table.
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* @param value
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* Value to associate with key.
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* @return
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* 0 if ok, or negative value on error.
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*/
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static inline int
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rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht,
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uint32_t key, uint16_t value)
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{
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/*
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* The writing of a new value to the hash table is done as a single
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* 64bit operation. This should help prevent individual entries being
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* corrupted due to race conditions, but it's still possible to
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* overwrite entries that have just been made valid.
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*/
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const uint64_t new_entry = ((uint64_t)(key) << 32) |
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((uint64_t)(value) << 16) |
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1; /* 1 = is_entry bit. */
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const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
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uint32_t i;
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for (i = 0; i < ht->entries_per_bucket; i++) {
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/* Set entry if unused. */
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if (! ht->t[bucket + i].entry.is_entry) {
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ht->t[bucket + i].whole_entry = new_entry;
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ht->used_entries++;
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return 0;
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}
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/* Change value if key already exists. */
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if (ht->t[bucket + i].entry.key == key) {
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ht->t[bucket + i].entry.value = value;
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return 0;
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}
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}
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return -ENOSPC; /* No space in bucket. */
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}
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/**
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* Remove a key from an existing hash table. This operation is not multi-thread
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* safe and should only be called from one thread.
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*
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* @param ht
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* Hash table to remove the key from.
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* @param key
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* Key to remove from the hash table.
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* @return
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* 0 if ok, or negative value on error.
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*/
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static inline int
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rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key)
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{
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const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
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uint32_t last_entry = ht->entries_per_bucket - 1;
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uint32_t i, j;
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for (i = 0; i < ht->entries_per_bucket; i++) {
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if (ht->t[bucket + i].entry.key == key) {
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/* Find last key in bucket. */
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for (j = ht->entries_per_bucket - 1; j > i; j-- ) {
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if (! ht->t[bucket + j].entry.is_entry) {
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last_entry = j - 1;
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}
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}
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/*
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* Move the last key to the deleted key's position, and
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* delete the last key. lastEntry and i may be same but
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* it doesn't matter.
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*/
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ht->t[bucket + i].whole_entry =
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ht->t[bucket + last_entry].whole_entry;
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ht->t[bucket + last_entry].whole_entry = 0;
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ht->used_entries--;
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return 0;
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}
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}
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return -ENOENT; /* Key didn't exist. */
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}
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/**
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* Find a key in the hash table. This operation is multi-thread safe.
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*
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* @param ht
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* Hash table to look in.
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* @param key
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* Key to find.
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* @return
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* The value that was associated with the key, or negative value on error.
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*/
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static inline int
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rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key)
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{
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const uint32_t bucket = rte_fbk_hash_get_bucket(ht, key);
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union rte_fbk_hash_entry current_entry;
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uint32_t i;
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for (i = 0; i < ht->entries_per_bucket; i++) {
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/* Single read of entry, which should be atomic. */
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current_entry.whole_entry = ht->t[bucket + i].whole_entry;
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if (! current_entry.entry.is_entry) {
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return -ENOENT; /* Error once we hit an empty field. */
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}
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if (current_entry.entry.key == key) {
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return current_entry.entry.value;
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}
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}
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return -ENOENT; /* Key didn't exist. */
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}
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/**
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* Delete all entries in a hash table. This operation is not multi-thread
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* safe and should only be called from one thread.
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*
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* @param ht
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* Hash table to delete entries in.
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*/
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static inline void
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rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht)
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{
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memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries);
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ht->used_entries = 0;
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}
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/**
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* Find what fraction of entries are being used.
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*
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* @param ht
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* Hash table to find how many entries are being used in.
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* @return
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* Load factor of the hash table, or negative value on error.
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*/
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static inline double
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rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht)
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{
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return (double)ht->used_entries / (double)ht->entries;
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}
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/**
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* Performs a lookup for an existing hash table, and returns a pointer to
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* the table if found.
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*
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* @param name
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* Name of the hash table to find
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*
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* @return
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* pointer to hash table structure or NULL on error with rte_errno
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* set appropriately. Possible rte_errno values include:
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* - ENOENT - required entry not available to return.
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*/
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struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name);
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/**
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* Create a new hash table for use with four byte keys.
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*
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* @param params
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* Parameters used in creation of hash table.
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*
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* @return
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* Pointer to hash table structure that is used in future hash table
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* operations, or NULL on error with rte_errno set appropriately.
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* Possible rte_errno error values include:
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* - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
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* - E_RTE_SECONDARY - function was called from a secondary process instance
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* - E_RTE_NO_TAILQ - no tailq list could be got for the fbk hash table list
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* - EINVAL - invalid parameter value passed to function
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* - ENOSPC - the maximum number of memzones has already been allocated
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* - EEXIST - a memzone with the same name already exists
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* - ENOMEM - no appropriate memory area found in which to create memzone
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*/
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struct rte_fbk_hash_table * \
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rte_fbk_hash_create(const struct rte_fbk_hash_params *params);
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/**
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* Free all memory used by a hash table.
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* Has no effect on hash tables allocated in memory zones
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*
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* @param ht
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* Hash table to deallocate.
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*/
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void rte_fbk_hash_free(struct rte_fbk_hash_table *ht);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _RTE_FBK_HASH_H_ */
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