update sources to ceph Nautilus 14.2.1

[ceph.git] / ceph / src / seastar / dpdk / lib / librte_hash / rte_fbk_hash.h

/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _RTE_FBK_HASH_H_
#define _RTE_FBK_HASH_H_

/**
 * @file
 *
 * This is a hash table implementation for four byte keys (fbk).
 *
 * Note that the return value of the add function should always be checked as,
 * if a bucket is full, the key is not added even if there is space in other
 * buckets. This keeps the lookup function very simple and therefore fast.
 */

#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>
/** Default four-byte key hash function if none is specified. */
#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
/** Initialising value used when calculating hash. */
#define RTE_FBK_HASH_INIT_VAL_DEFAULT           0xFFFFFFFF
#endif

/** The maximum number of entries in the hash table that is supported. */
#define RTE_FBK_HASH_ENTRIES_MAX                (1 << 20)

/** The maximum number of entries in each bucket that is supported. */
#define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX     256

/** Maximum size of string for naming the hash. */
#define RTE_FBK_HASH_NAMESIZE                   32

/** Type of function that can be used for calculating the hash value. */
typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val);

/** Parameters used when creating four-byte key hash table. */
struct rte_fbk_hash_params {
        const char *name;               /**< Name of the hash table. */
        uint32_t entries;               /**< Total number of entries. */
        uint32_t entries_per_bucket;    /**< Number of entries in a bucket. */
        int socket_id;                  /**< Socket to allocate memory on. */
        rte_fbk_hash_fn hash_func;      /**< The hash function. */
        uint32_t init_val;              /**< For initialising hash function. */
};

/** Individual entry in the four-byte key hash table. */
union rte_fbk_hash_entry {
        uint64_t whole_entry;           /**< For accessing entire entry. */
        struct {
                uint16_t is_entry;      /**< Non-zero if entry is active. */
                uint16_t value;         /**< Value returned by lookup. */
                uint32_t key;           /**< Key used to find value. */
        } entry;                        /**< For accessing each entry part. */
};


/** The four-byte key hash table structure. */
struct rte_fbk_hash_table {
        char name[RTE_FBK_HASH_NAMESIZE];       /**< Name of the hash. */
        uint32_t entries;               /**< Total number of entries. */
        uint32_t entries_per_bucket;    /**< Number of entries in a bucket. */
        uint32_t used_entries;          /**< How many entries are used. */
        uint32_t bucket_mask;           /**< To find which bucket the key is in. */
        uint32_t bucket_shift;          /**< Convert bucket to table offset. */
        rte_fbk_hash_fn hash_func;      /**< The hash function. */
        uint32_t init_val;              /**< For initialising hash function. */

        /** A flat table of all buckets. */
        union rte_fbk_hash_entry t[];
};

/**
 * Find the offset into hash table of the bucket containing a particular key.
 *
 * @param ht
 *   Pointer to hash table.
 * @param key
 *   Key to calculate bucket for.
 * @return
 *   Offset into hash table.
 */
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;
}

/**
 * Add a key to an existing hash table with bucket id.
 * This operation is not multi-thread safe
 * and should only be called from one thread.
 *
 * @param ht
 *   Hash table to add the key to.
 * @param key
 *   Key to add to the hash table.
 * @param value
 *   Value to associate with key.
 * @param bucket
 *   Bucket to associate with key.
 * @return
 *   0 if ok, or negative value on error.
 */
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. */
}

/**
 * Add a key to an existing hash table. This operation is not multi-thread safe
 * and should only be called from one thread.
 *
 * @param ht
 *   Hash table to add the key to.
 * @param key
 *   Key to add to the hash table.
 * @param value
 *   Value to associate with key.
 * @return
 *   0 if ok, or negative value on error.
 */
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));
}

/**
 * Remove a key with a given bucket id from an existing hash table.
 * This operation is not multi-thread
 * safe and should only be called from one thread.
 *
 * @param ht
 *   Hash table to remove the key from.
 * @param key
 *   Key to remove from the hash table.
 * @param bucket
 *   Bucket id associate with key.
 * @return
 *   0 if ok, or negative value on error.
 */
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. */
}

/**
 * Remove a key from an existing hash table. This operation is not multi-thread
 * safe and should only be called from one thread.
 *
 * @param ht
 *   Hash table to remove the key from.
 * @param key
 *   Key to remove from the hash table.
 * @return
 *   0 if ok, or negative value on error.
 */
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));
}

/**
 * Find a key in the hash table with a given bucketid.
 * This operation is multi-thread safe.
 *
 * @param ht
 *   Hash table to look in.
 * @param key
 *   Key to find.
 * @param bucket
 *   Bucket associate to the key.
 * @return
 *   The value that was associated with the key, or negative value on error.
 */
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. */
}

/**
 * Find a key in the hash table. This operation is multi-thread safe.
 *
 * @param ht
 *   Hash table to look in.
 * @param key
 *   Key to find.
 * @return
 *   The value that was associated with the key, or negative value on error.
 */
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));
}

/**
 * Delete all entries in a hash table. This operation is not multi-thread
 * safe and should only be called from one thread.
 *
 * @param ht
 *   Hash table to delete entries in.
 */
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;
}

/**
 * Find what fraction of entries are being used.
 *
 * @param ht
 *   Hash table to find how many entries are being used in.
 * @return
 *   Load factor of the hash table, or negative value on error.
 */
static inline double
rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht)
{
        return (double)ht->used_entries / (double)ht->entries;
}

/**
 * Performs a lookup for an existing hash table, and returns a pointer to
 * the table if found.
 *
 * @param name
 *   Name of the hash table to find
 *
 * @return
 *   pointer to hash table structure or NULL on error with rte_errno
 *   set appropriately. Possible rte_errno values include:
 *    - ENOENT - required entry not available to return.
 */
struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name);

/**
 * Create a new hash table for use with four byte keys.
 *
 * @param params
 *   Parameters used in creation of hash table.
 *
 * @return
 *   Pointer to hash table structure that is used in future hash table
 *   operations, or NULL on error with rte_errno set appropriately.
 *   Possible rte_errno error values include:
 *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
 *    - E_RTE_SECONDARY - function was called from a secondary process instance
 *    - EINVAL - invalid parameter value passed to function
 *    - ENOSPC - the maximum number of memzones has already been allocated
 *    - EEXIST - a memzone with the same name already exists
 *    - ENOMEM - no appropriate memory area found in which to create memzone
 */
struct rte_fbk_hash_table * \
rte_fbk_hash_create(const struct rte_fbk_hash_params *params);

/**
 * Free all memory used by a hash table.
 * Has no effect on hash tables allocated in memory zones
 *
 * @param ht
 *   Hash table to deallocate.
 */
void rte_fbk_hash_free(struct rte_fbk_hash_table *ht);

#ifdef __cplusplus
}
#endif

#endif /* _RTE_FBK_HASH_H_ */