/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
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
*/
/*
* Created on Sep 9, 2015
*/
package com.bigdata.service.geospatial;
import java.util.NoSuchElementException;
import org.apache.log4j.Logger;
import com.bigdata.btree.ITuple;
import com.bigdata.btree.KeyOutOfRangeException;
import com.bigdata.btree.filter.Advancer;
import com.bigdata.btree.keys.IKeyBuilder;
import com.bigdata.btree.keys.KeyBuilder;
import com.bigdata.rdf.internal.IV;
import com.bigdata.rdf.internal.IVUtility;
import com.bigdata.rdf.internal.impl.extensions.GeoSpatialLiteralExtension;
import com.bigdata.rdf.internal.impl.literal.LiteralExtensionIV;
import com.bigdata.rdf.model.BigdataLiteral;
import com.bigdata.rdf.model.BigdataValue;
import com.bigdata.rdf.spo.SPO;
/**
* Advances the cursor to the next zOrderKey that is greater or equal than the
* first point in the next region. Note that this next key is not necessarily a
* hit (but, depending on the data) this might be a miss again.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
*/
public class ZOrderIndexBigMinAdvancer extends Advancer<SPO> {
private static final long serialVersionUID = -6438977707376228799L;
private static final transient Logger log = Logger
.getLogger(ZOrderIndexBigMinAdvancer.class);
final protected static boolean DEBUG = log.isDebugEnabled();
// Search min (upper left) byte array as z-order string (no leading zero)
private final byte[] searchMinZOrder;
// Search max (lower right) byte array as z-order string (no leading zero)
private final byte[] searchMaxZOrder;
// the position within the index in which we find the zOrderComponent
private final int zOrderComponentPos;
// the GeoSpatialLiteralExtension object
private final GeoSpatialLiteralExtension<BigdataValue> litExt;
private final ZOrderRangeScanUtil rangeScanUtil;
// counters object for statistics
private final GeoSpatialCounters geoSpatialCounters;
private transient IKeyBuilder keyBuilder;
public ZOrderIndexBigMinAdvancer(
final byte[] searchMinZOrder, /* the minimum search key (top left) */
final byte[] searchMaxZOrder, /* the maximum search key (bottom right) */
final GeoSpatialLiteralExtension<BigdataValue> litExt,
final int zOrderComponentPos /* position of the zOrder in the index */,
final GeoSpatialCounters geoSpatialCounters) {
this.litExt = litExt;
this.searchMinZOrder = litExt.unpadLeadingZero(searchMinZOrder);
// this.seachMinLong = litExt.fromZOrderByteArray(this.searchMinZOrder);
this.searchMaxZOrder = litExt.unpadLeadingZero(searchMaxZOrder);
// this.seachMaxLong = litExt.fromZOrderByteArray(this.searchMaxZOrder);
this.zOrderComponentPos = zOrderComponentPos;
this.geoSpatialCounters = geoSpatialCounters;
this.rangeScanUtil =
new ZOrderRangeScanUtil(
this.searchMinZOrder, this.searchMaxZOrder, litExt.getNumDimensions());
}
@SuppressWarnings("rawtypes")
@Override
protected void advance(final ITuple<SPO> tuple) {
if (keyBuilder == null) {
keyBuilder = KeyBuilder.newInstance();
}
// iterate unless tuple in range is found or we reached the end
ITuple<SPO> curTuple = tuple;
while(curTuple!=null) {
if (DEBUG) {
log.debug("Advancor visiting tuple: " + curTuple);
}
final long rangeCheckCalStart = System.nanoTime();
final byte[] key = curTuple.getKey();
keyBuilder.reset();
// decode components up to (and including) the z-order string
final IV[] ivs = IVUtility.decode(key,zOrderComponentPos+1);
// encode everything up to (and excluding) the z-order component "as is"
for (int i=0; i<ivs.length-1; i++) {
IVUtility.encode(keyBuilder, ivs[i]);
}
// this is the z-order literal
@SuppressWarnings("unchecked")
final LiteralExtensionIV<BigdataLiteral> zOrderIv =
(LiteralExtensionIV<BigdataLiteral>)ivs[ivs.length-1];
// current record (aka dividing record) as unsigned
final byte[] dividingRecord =
litExt.toZOrderByteArray(zOrderIv.getDelegate());
final boolean inRange = rangeScanUtil.isInSearchRange(dividingRecord);
final long rangeCheckCalEnd = System.nanoTime();
geoSpatialCounters.addRangeCheckCalculationTime(rangeCheckCalEnd-rangeCheckCalStart);
if (!inRange) {
// this is a miss
geoSpatialCounters.registerZOrderIndexMiss();
long bigMinCalStart = System.nanoTime();
if (log.isDebugEnabled()) {
log.debug("-> tuple " + curTuple + " not in range");
}
// calculate bigmin over the z-order component
final byte[] bigMin = rangeScanUtil.calculateBigMin(dividingRecord);
// pad a zero
final LiteralExtensionIV bigMinIv = litExt.createIVFromZOrderByteArray(bigMin);
IVUtility.encode(keyBuilder, bigMinIv);
final long bigMinCalEnd = System.nanoTime();
geoSpatialCounters.addBigMinCalculationTime(bigMinCalEnd-bigMinCalStart);
// advance to the specified key ...
try {
if (log.isDebugEnabled()) {
log.debug("-> advancing to bigmin: " + bigMinIv);
}
ITuple<SPO> next = src.seek(keyBuilder.getKey());
// ... or the next higher one
if (next==null) {
next = src.next();
}
// continue iterate
curTuple = next;
} catch (NoSuchElementException e) {
throw new KeyOutOfRangeException("Advancer out of search range");
}
} else {
geoSpatialCounters.registerZOrderIndexHit();
return;
}
}
}
}