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/***************************************************************************//**
Copyright (c) 2010, 2011, Oracle and/or its affiliates. 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.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
*****************************************************************************/
/******************************************************************//**
@file ut/ut0bh.cc
Binary min-heap implementation.
Created 2010-05-28 by Sunny Bains
*******************************************************/
#include "ut0bh.h"
#include "ut0mem.h"
#ifdef UNIV_NONINL
#include "ut0bh.ic"
#endif
#include <string.h>
/**********************************************************************//**
Create a binary heap.
@return a new binary heap */
UNIV_INTERN
ib_bh_t*
ib_bh_create(
/*=========*/
ib_bh_cmp_t compare, /*!< in: comparator */
ulint sizeof_elem, /*!< in: size of one element */
ulint max_elems) /*!< in: max elements allowed */
{
ulint sz;
ib_bh_t* ib_bh;
sz = sizeof(*ib_bh) + (sizeof_elem * max_elems);
ib_bh = (ib_bh_t*) ut_malloc(sz);
memset(ib_bh, 0x0, sz);
ib_bh->compare = compare;
ib_bh->max_elems = max_elems;
ib_bh->sizeof_elem = sizeof_elem;
return(ib_bh);
}
/**********************************************************************//**
Free a binary heap.
@return a new binary heap */
UNIV_INTERN
void
ib_bh_free(
/*=======*/
ib_bh_t* ib_bh) /*!< in/own: instance */
{
ut_free(ib_bh);
}
/**********************************************************************//**
Add an element to the binary heap. Note: The element is copied.
@return pointer to added element or NULL if full. */
UNIV_INTERN
void*
ib_bh_push(
/*=======*/
ib_bh_t* ib_bh, /*!< in/out: instance */
const void* elem) /*!< in: element to add */
{
void* ptr;
if (ib_bh_is_full(ib_bh)) {
return(NULL);
} else if (ib_bh_is_empty(ib_bh)) {
++ib_bh->n_elems;
return(ib_bh_set(ib_bh, 0, elem));
} else {
ulint i;
i = ib_bh->n_elems;
++ib_bh->n_elems;
for (ptr = ib_bh_get(ib_bh, i >> 1);
i > 0 && ib_bh->compare(ptr, elem) > 0;
i >>= 1, ptr = ib_bh_get(ib_bh, i >> 1)) {
ib_bh_set(ib_bh, i, ptr);
}
ptr = ib_bh_set(ib_bh, i, elem);
}
return(ptr);
}
/**********************************************************************//**
Remove the first element from the binary heap. */
UNIV_INTERN
void
ib_bh_pop(
/*======*/
ib_bh_t* ib_bh) /*!< in/out: instance */
{
byte* ptr;
byte* last;
ulint parent = 0;
if (ib_bh_is_empty(ib_bh)) {
return;
} else if (ib_bh_size(ib_bh) == 1) {
--ib_bh->n_elems;
return;
}
last = (byte*) ib_bh_last(ib_bh);
/* Start from the child node */
ptr = (byte*) ib_bh_get(ib_bh, 1);
while (ptr < last) {
/* If the "right" child node is < "left" child node */
if (ib_bh->compare(ptr + ib_bh->sizeof_elem, ptr) < 0) {
ptr += ib_bh->sizeof_elem;
}
if (ib_bh->compare(last, ptr) <= 0) {
break;
}
ib_bh_set(ib_bh, parent, ptr);
parent = (ptr - (byte*) ib_bh_first(ib_bh))
/ ib_bh->sizeof_elem;
if ((parent << 1) >= ib_bh_size(ib_bh)) {
break;
}
ptr = (byte*) ib_bh_get(ib_bh, parent << 1);
}
--ib_bh->n_elems;
ib_bh_set(ib_bh, parent, last);
}
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