com.orientechnologies.orient.core.index.sbtree.OSBTreeMapEntryIterator Maven / Gradle / Ivy
/*
*
* * Copyright 2014 Orient Technologies LTD (info(at)orientechnologies.com)
* *
* * Licensed under the Apache License, Version 2.0 (the "License");
* * you may not use this file except in compliance with the License.
* * You may obtain a copy of the License at
* *
* * http://www.apache.org/licenses/LICENSE-2.0
* *
* * Unless required by applicable law or agreed to in writing, software
* * distributed under the License is distributed on an "AS IS" BASIS,
* * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* * See the License for the specific language governing permissions and
* * limitations under the License.
* *
* * For more information: http://www.orientechnologies.com
*
*/
package com.orientechnologies.orient.core.index.sbtree;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import com.orientechnologies.orient.core.db.record.OIdentifiable;
import com.orientechnologies.orient.core.db.record.ridbag.sbtree.OIndexRIDContainer;
/**
* @author Artem Orobets (enisher-at-gmail.com)
*/
public class OSBTreeMapEntryIterator implements Iterator> {
private LinkedList> preFetchedValues;
private final OTreeInternal sbTree;
private K firstKey;
private Map.Entry currentEntry;
private final int prefetchSize;
public OSBTreeMapEntryIterator(OTreeInternal sbTree) {
this(sbTree, 8000);
}
public OSBTreeMapEntryIterator(OTreeInternal sbTree, int prefetchSize) {
this.sbTree = sbTree;
this.prefetchSize = prefetchSize;
if (sbTree.size() == 0) {
this.preFetchedValues = null;
return;
}
this.preFetchedValues = new LinkedList>();
firstKey = sbTree.firstKey();
prefetchData(true);
}
private void prefetchData(boolean firstTime) {
sbTree.loadEntriesMajor(firstKey, firstTime, true, new OTreeInternal.RangeResultListener() {
@Override
public boolean addResult(final Map.Entry entry) {
final V value = entry.getValue();
final V resultValue;
if (value instanceof OIndexRIDContainer)
resultValue = (V) new HashSet((Collection) value);
else
resultValue = value;
preFetchedValues.add(new Map.Entry() {
@Override
public K getKey() {
return entry.getKey();
}
@Override
public V getValue() {
return resultValue;
}
@Override
public V setValue(V v) {
throw new UnsupportedOperationException("setValue");
}
});
return preFetchedValues.size() <= prefetchSize;
}
});
if (preFetchedValues.isEmpty())
preFetchedValues = null;
else
firstKey = preFetchedValues.getLast().getKey();
}
@Override
public boolean hasNext() {
return preFetchedValues != null;
}
@Override
public Map.Entry next() {
final Map.Entry entry = preFetchedValues.removeFirst();
if (preFetchedValues.isEmpty())
prefetchData(false);
currentEntry = entry;
return entry;
}
@Override
public void remove() {
sbTree.remove(currentEntry.getKey());
currentEntry = null;
}
}