mariadb/include/hash0hash.ic

/*****************************************************************************

Copyright (c) 1997, 2009, Innobase Oy. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA

*****************************************************************************/

/**************************************************//**
@file include/hash0hash.ic
The simple hash table utility

Created 5/20/1997 Heikki Tuuri
*******************************************************/

#include "ut0rnd.h"

/************************************************************//**
Gets the nth cell in a hash table.
@return	pointer to cell */
UNIV_INLINE
hash_cell_t*
hash_get_nth_cell(
/*==============*/
	hash_table_t*	table,	/*!< in: hash table */
	ulint		n)	/*!< in: cell index */
{
	ut_ad(n < table->n_cells);

	return(table->array + n);
}

/*************************************************************//**
Clears a hash table so that all the cells become empty. */
UNIV_INLINE
void
hash_table_clear(
/*=============*/
	hash_table_t*	table)	/*!< in/out: hash table */
{
	memset(table->array, 0x0,
	       table->n_cells * sizeof(*table->array));
}

/*************************************************************//**
Returns the number of cells in a hash table.
@return	number of cells */
UNIV_INLINE
ulint
hash_get_n_cells(
/*=============*/
	hash_table_t*	table)	/*!< in: table */
{
	return(table->n_cells);
}

/**************************************************************//**
Calculates the hash value from a folded value.
@return	hashed value */
UNIV_INLINE
ulint
hash_calc_hash(
/*===========*/
	ulint		fold,	/*!< in: folded value */
	hash_table_t*	table)	/*!< in: hash table */
{
	return(ut_hash_ulint(fold, table->n_cells));
}

#ifndef UNIV_HOTBACKUP
/************************************************************//**
Gets the mutex index for a fold value in a hash table.
@return	mutex number */
UNIV_INLINE
ulint
hash_get_mutex_no(
/*==============*/
	hash_table_t*	table,	/*!< in: hash table */
	ulint		fold)	/*!< in: fold */
{
	ut_ad(ut_is_2pow(table->n_mutexes));
	return(ut_2pow_remainder(hash_calc_hash(fold, table),
				 table->n_mutexes));
}

/************************************************************//**
Gets the nth heap in a hash table.
@return	mem heap */
UNIV_INLINE
mem_heap_t*
hash_get_nth_heap(
/*==============*/
	hash_table_t*	table,	/*!< in: hash table */
	ulint		i)	/*!< in: index of the heap */
{
	ut_ad(i < table->n_mutexes);

	return(table->heaps[i]);
}

/************************************************************//**
Gets the heap for a fold value in a hash table.
@return	mem heap */
UNIV_INLINE
mem_heap_t*
hash_get_heap(
/*==========*/
	hash_table_t*	table,	/*!< in: hash table */
	ulint		fold)	/*!< in: fold */
{
	ulint	i;

	if (table->heap) {
		return(table->heap);
	}

	i = hash_get_mutex_no(table, fold);

	return(hash_get_nth_heap(table, i));
}

/************************************************************//**
Gets the nth mutex in a hash table.
@return	mutex */
UNIV_INLINE
mutex_t*
hash_get_nth_mutex(
/*===============*/
	hash_table_t*	table,	/*!< in: hash table */
	ulint		i)	/*!< in: index of the mutex */
{
	ut_ad(i < table->n_mutexes);

	return(table->mutexes + i);
}

/************************************************************//**
Gets the mutex for a fold value in a hash table.
@return	mutex */
UNIV_INLINE
mutex_t*
hash_get_mutex(
/*===========*/
	hash_table_t*	table,	/*!< in: hash table */
	ulint		fold)	/*!< in: fold */
{
	ulint	i;

	i = hash_get_mutex_no(table, fold);

	return(hash_get_nth_mutex(table, i));
}
#endif /* !UNIV_HOTBACKUP */