rte_fbk_hash.h

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/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
 *   All rights reserved.
 *
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 *
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 *       notice, this list of conditions and the following disclaimer.
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 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
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 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef _RTE_FBK_HASH_H_
#define _RTE_FBK_HASH_H_

#include <stdint.h>
#include <errno.h>
#include <sys/queue.h>

#ifdef __cplusplus
extern "C" {
#endif

#include <string.h>

#ifndef RTE_FBK_HASH_FUNC_DEFAULT
#if defined(RTE_MACHINE_CPUFLAG_SSE4_2) || defined(RTE_MACHINE_CPUFLAG_CRC32)
#include <rte_hash_crc.h>
#define RTE_FBK_HASH_FUNC_DEFAULT               rte_hash_crc_4byte
#else
#include <rte_jhash.h>
#define RTE_FBK_HASH_FUNC_DEFAULT               rte_jhash_1word
#endif
#endif

#ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT

#define RTE_FBK_HASH_INIT_VAL_DEFAULT           0xFFFFFFFF
#endif

#define RTE_FBK_HASH_ENTRIES_MAX                (1 << 20)

#define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX     256

#define RTE_FBK_HASH_NAMESIZE                   32

typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val);

struct rte_fbk_hash_params {
        const char *name;               
        uint32_t entries;               
        uint32_t entries_per_bucket;    
        int socket_id;                  
        rte_fbk_hash_fn hash_func;      
        uint32_t init_val;              
};

union rte_fbk_hash_entry {
        uint64_t whole_entry;           
        struct {
                uint16_t is_entry;      
                uint16_t value;         
                uint32_t key;           
        } entry;                        
};


struct rte_fbk_hash_table {
        char name[RTE_FBK_HASH_NAMESIZE];       
        uint32_t entries;               
        uint32_t entries_per_bucket;    
        uint32_t used_entries;          
        uint32_t bucket_mask;           
        uint32_t bucket_shift;          
        rte_fbk_hash_fn hash_func;      
        uint32_t init_val;              
        union rte_fbk_hash_entry t[];
};

static inline uint32_t
rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key)
{
        return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) <<
                        ht->bucket_shift;
}

static inline int
rte_fbk_hash_add_key_with_bucket(struct rte_fbk_hash_table *ht,
                        uint32_t key, uint16_t value, uint32_t bucket)
{
        /*
         * The writing of a new value to the hash table is done as a single
         * 64bit operation. This should help prevent individual entries being
         * corrupted due to race conditions, but it's still possible to
         * overwrite entries that have just been made valid.
         */
        const uint64_t new_entry = ((uint64_t)(key) << 32) |
                        ((uint64_t)(value) << 16) |
                        1;  /* 1 = is_entry bit. */
        uint32_t i;

        for (i = 0; i < ht->entries_per_bucket; i++) {
                /* Set entry if unused. */
                if (! ht->t[bucket + i].entry.is_entry) {
                        ht->t[bucket + i].whole_entry = new_entry;
                        ht->used_entries++;
                        return 0;
                }
                /* Change value if key already exists. */
                if (ht->t[bucket + i].entry.key == key) {
                        ht->t[bucket + i].entry.value = value;
                        return 0;
                }
        }

        return -ENOSPC; /* No space in bucket. */
}

static inline int
rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht,
                        uint32_t key, uint16_t value)
{
        return rte_fbk_hash_add_key_with_bucket(ht,
                                key, value, rte_fbk_hash_get_bucket(ht, key));
}

static inline int
rte_fbk_hash_delete_key_with_bucket(struct rte_fbk_hash_table *ht,
                                        uint32_t key, uint32_t bucket)
{
        uint32_t last_entry = ht->entries_per_bucket - 1;
        uint32_t i, j;

        for (i = 0; i < ht->entries_per_bucket; i++) {
                if (ht->t[bucket + i].entry.key == key) {
                        /* Find last key in bucket. */
                        for (j = ht->entries_per_bucket - 1; j > i; j-- ) {
                                if (! ht->t[bucket + j].entry.is_entry) {
                                        last_entry = j - 1;
                                }
                        }
                        /*
                         * Move the last key to the deleted key's position, and
                         * delete the last key. lastEntry and i may be same but
                         * it doesn't matter.
                         */
                        ht->t[bucket + i].whole_entry =
                                        ht->t[bucket + last_entry].whole_entry;
                        ht->t[bucket + last_entry].whole_entry = 0;

                        ht->used_entries--;
                        return 0;
                }
        }

        return -ENOENT; /* Key didn't exist. */
}

static inline int
rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key)
{
        return rte_fbk_hash_delete_key_with_bucket(ht,
                                key, rte_fbk_hash_get_bucket(ht, key));
}

static inline int
rte_fbk_hash_lookup_with_bucket(const struct rte_fbk_hash_table *ht,
                                uint32_t key, uint32_t bucket)
{
        union rte_fbk_hash_entry current_entry;
        uint32_t i;

        for (i = 0; i < ht->entries_per_bucket; i++) {
                /* Single read of entry, which should be atomic. */
                current_entry.whole_entry = ht->t[bucket + i].whole_entry;
                if (! current_entry.entry.is_entry) {
                        return -ENOENT; /* Error once we hit an empty field. */
                }
                if (current_entry.entry.key == key) {
                        return current_entry.entry.value;
                }
        }
        return -ENOENT; /* Key didn't exist. */
}

static inline int
rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key)
{
        return rte_fbk_hash_lookup_with_bucket(ht,
                                key, rte_fbk_hash_get_bucket(ht, key));
}

static inline void
rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht)
{
        memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries);
        ht->used_entries = 0;
}

static inline double
rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht)
{
        return (double)ht->used_entries / (double)ht->entries;
}

struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name);

struct rte_fbk_hash_table * \
rte_fbk_hash_create(const struct rte_fbk_hash_params *params);

void rte_fbk_hash_free(struct rte_fbk_hash_table *ht);

#ifdef __cplusplus
}
#endif

#endif /* _RTE_FBK_HASH_H_ */