mirror of
https://github.com/oliverschmidt/contiki.git
synced 2024-08-16 22:28:59 +00:00
228 lines
6.5 KiB
C
228 lines
6.5 KiB
C
/*
|
|
* Copyright (c) 2010, Swedish Institute of Computer Science
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. 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.
|
|
* 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
|
|
*/
|
|
|
|
/**
|
|
* \file
|
|
* A binary search index for attributes that are constrained to be
|
|
* monotonically increasing, which is a rather common pattern for
|
|
* time series or keys. Since this index has no storage overhead,
|
|
* it does not wear out the flash memory nor does it occupy any
|
|
* space. Furthermore, unlike B+-trees, it has a O(1) memory
|
|
* footprint in relation to the number of data items.
|
|
* \author
|
|
* Nicolas Tsiftes <nvt@sics.se>
|
|
*/
|
|
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
|
|
#include "index.h"
|
|
#include "relation.h"
|
|
#include "result.h"
|
|
#include "storage.h"
|
|
|
|
#define DEBUG DEBUG_NONE
|
|
#include "net/ip/uip-debug.h"
|
|
|
|
struct search_handle {
|
|
index_t *index;
|
|
tuple_id_t start_row;
|
|
tuple_id_t end_row;
|
|
};
|
|
|
|
struct search_handle handle;
|
|
|
|
static db_result_t null_op(index_t *);
|
|
static db_result_t insert(index_t *, attribute_value_t *, tuple_id_t);
|
|
static db_result_t delete(index_t *, attribute_value_t *);
|
|
static tuple_id_t get_next(index_iterator_t *);
|
|
|
|
/*
|
|
* The create, destroy, load, release, insert, and delete operations
|
|
* of the index API always succeed because the index does not store
|
|
* items separately from the row file. The four former operations share
|
|
* the same signature, and are thus implemented by the null_op function
|
|
* to save space.
|
|
*/
|
|
index_api_t index_inline = {
|
|
INDEX_INLINE,
|
|
INDEX_API_EXTERNAL | INDEX_API_COMPLETE | INDEX_API_RANGE_QUERIES,
|
|
null_op,
|
|
null_op,
|
|
null_op,
|
|
null_op,
|
|
insert,
|
|
delete,
|
|
get_next
|
|
};
|
|
|
|
static attribute_value_t *
|
|
get_value(tuple_id_t *index, relation_t *rel, attribute_t *attr)
|
|
{
|
|
unsigned char row[rel->row_length];
|
|
static attribute_value_t value;
|
|
|
|
if(DB_ERROR(storage_get_row(rel, index, row))) {
|
|
return NULL;
|
|
}
|
|
|
|
if(DB_ERROR(relation_get_value(rel, attr, row, &value))) {
|
|
PRINTF("DB: Unable to retrieve a value from tuple %ld\n", (long)(*index));
|
|
return NULL;
|
|
}
|
|
|
|
return &value;
|
|
}
|
|
|
|
static tuple_id_t
|
|
binary_search(index_iterator_t *index_iterator,
|
|
attribute_value_t *target_value,
|
|
int exact_match)
|
|
{
|
|
relation_t *rel;
|
|
attribute_t *attr;
|
|
attribute_value_t *cmp_value;
|
|
tuple_id_t min;
|
|
tuple_id_t max;
|
|
tuple_id_t center;
|
|
|
|
rel = index_iterator->index->rel;
|
|
attr = index_iterator->index->attr;
|
|
|
|
max = relation_cardinality(rel);
|
|
if(max == INVALID_TUPLE) {
|
|
return INVALID_TUPLE;
|
|
}
|
|
max--;
|
|
min = 0;
|
|
|
|
do {
|
|
center = min + ((max - min) / 2);
|
|
|
|
cmp_value = get_value(¢er, rel, attr);
|
|
if(cmp_value == NULL) {
|
|
PRINTF("DB: Failed to get the center value, index = %ld\n",
|
|
(long)center);
|
|
return INVALID_TUPLE;
|
|
}
|
|
|
|
if(db_value_to_long(target_value) > db_value_to_long(cmp_value)) {
|
|
min = center + 1;
|
|
} else {
|
|
max = center - 1;
|
|
}
|
|
} while(min <= max &&
|
|
db_value_to_long(target_value) != db_value_to_long(cmp_value));
|
|
|
|
if(exact_match &&
|
|
db_value_to_long(target_value) != db_value_to_long(cmp_value)) {
|
|
PRINTF("DB: Could not find value %ld in the inline index\n",
|
|
db_value_to_long(target_value));
|
|
return INVALID_TUPLE;
|
|
}
|
|
|
|
return center;
|
|
}
|
|
|
|
static tuple_id_t
|
|
range_search(index_iterator_t *index_iterator,
|
|
tuple_id_t *start, tuple_id_t *end)
|
|
{
|
|
attribute_value_t *low_target;
|
|
attribute_value_t *high_target;
|
|
int exact_match;
|
|
|
|
low_target = &index_iterator->min_value;
|
|
high_target = &index_iterator->max_value;
|
|
|
|
PRINTF("DB: Search index for value range (%ld, %ld)\n",
|
|
db_value_to_long(low_target), db_value_to_long(high_target));
|
|
|
|
exact_match = db_value_to_long(low_target) == db_value_to_long(high_target);
|
|
|
|
/* Optimize later so that the other search uses the result
|
|
from the first one. */
|
|
*start = binary_search(index_iterator, low_target, exact_match);
|
|
if(*start == INVALID_TUPLE) {
|
|
return DB_INDEX_ERROR;
|
|
}
|
|
|
|
*end = binary_search(index_iterator, high_target, exact_match);
|
|
if(*end == INVALID_TUPLE) {
|
|
return DB_INDEX_ERROR;
|
|
}
|
|
return DB_OK;
|
|
}
|
|
|
|
static db_result_t
|
|
null_op(index_t *index)
|
|
{
|
|
return DB_OK;
|
|
}
|
|
|
|
static db_result_t
|
|
insert(index_t *index, attribute_value_t *value, tuple_id_t tuple_id)
|
|
{
|
|
return DB_OK;
|
|
}
|
|
|
|
static db_result_t
|
|
delete(index_t *index, attribute_value_t *value)
|
|
{
|
|
return DB_OK;
|
|
}
|
|
|
|
static tuple_id_t
|
|
get_next(index_iterator_t *iterator)
|
|
{
|
|
static tuple_id_t cached_start;
|
|
static tuple_id_t cached_end;
|
|
|
|
if(iterator->next_item_no == 0) {
|
|
/*
|
|
* We conduct the actual index search when the caller attempts to
|
|
* access the first item in the iteration. The first and last tuple
|
|
* id:s of the result get cached for subsequent iterations.
|
|
*/
|
|
if(DB_ERROR(range_search(iterator, &cached_start, &cached_end))) {
|
|
cached_start = 0;
|
|
cached_end = 0;
|
|
return INVALID_TUPLE;
|
|
}
|
|
PRINTF("DB: Cached the tuple range (%ld,%ld)\n",
|
|
(long)cached_start, (long)cached_end);
|
|
++iterator->next_item_no;
|
|
return cached_start;
|
|
} else if(cached_start + iterator->next_item_no <= cached_end) {
|
|
return cached_start + iterator->next_item_no++;
|
|
}
|
|
|
|
return INVALID_TUPLE;
|
|
}
|