com.bigdata.btree.BigdataSet Maven / Gradle / Ivy
/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
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 May 28, 2008
*/
package com.bigdata.btree;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedSet;
/**
* A {@link SortedSet} backed by a B+Tree.
*
* Note: The {@link BigdataMap} has the same concurrency constraints as the
* {@link BTree} - it is single-threaded for writes and allows concurrent
* readers.
*
* Note: The {@link BigdataSet} is actually flyweight wrapper around a
* {@link BigdataMap} whose keys and values are both formed from the values
* stored in this {@link SortedSet}.
*
* Note: Both {@link Set#equals(Object)} and {@link Set#hashCode()} are VERY
* expensive, but that is how they are defined.
*
* @param E
* The generic type for the elements stored in the set.
*
* @author Bryan Thompson
* @version $Id$
*/
public class BigdataSet extends AbstractSet implements SortedSet {
/**
* Text of the error message used when there are more than
* {@link Integer#MAX_VALUE} entries.
*/
protected static transient final String ERR_TOO_MANY = "Too many entries";
private final BigdataMap map;
public BigdataSet(IIndex ndx) {
map = new BigdataMap(ndx);
}
/**
* Ctor used to wrap a key-range of a {@link BigdataMap}.
*
* @param map
* The map which will impose the key-range constraints.
*/
BigdataSet(BigdataMap map) {
if (map == null)
throw new IllegalArgumentException();
this.map = map;
}
public boolean add(E key) {
E tmp = map.put(key, key);
// true if this set did not already contain the specified element.
return tmp == null;
}
public boolean remove(Object key) {
E tmp = map.remove(key);
// true if the set contained the specified element.
return tmp != null;
}
public void clear() {
map.clear();
}
public boolean contains(Object key) {
return map.containsKey(key);
}
public boolean isEmpty() {
return map.isEmpty();
}
/**
* The #of index entries. When there are more than {@link Integer#MAX_VALUE}
* entries then this method will report {@link Integer#MAX_VALUE} entries.
* If the backing index supports delete markers then an index scan will be
* performed in order to count the #of non-deleted index entries.
*/
public int size() {
return map.size();
}
/**
* The #of non-deleted entries in the map.
*
* @param exactCount
* When true the result will be an exact count,
* which will require a full key-range scan if delete markers are
* enabled for the index.
*
* @return The #of entries in the map. When exactCount is
* false and delete markers are being used, then this
* will be an upper bound.
*
* @see IRangeQuery#rangeCount(byte[], byte[])
*/
public long rangeCount(boolean exactCount) {
return map.rangeCount(exactCount);
}
public Iterator iterator() {
return map.keySet().iterator();
}
/**
* @todo override with implementation using chunked ordered writes.
*/
public boolean addAll(Collection c) {
return super.addAll(c);
}
/**
* @todo override with implementation using chunked ordered reads.
*/
public boolean containsAll(Collection c) {
return super.containsAll(c);
}
/**
* @todo override with implementation using chunked ordered writes.
*/
public boolean removeAll(Collection c) {
return super.removeAll(c);
}
/**
* @todo override with implementation using chunked ordered writes.
*/
public boolean retainAll(Collection c) {
return super.retainAll(c);
}
/**
* There is no means available to specify a {@link Comparator} for the
* {@link SortedSet}. Application keys are first converted into
* unsigned byte[] keys using the configured
* {@link ITupleSerializer} for the backing B+Tree. The index order is
* directly determined by those keys.
*
* @return Always returns null.
*/
final public Comparator comparator() {
return null;
}
/**
* Note: This is written using an {@link ITupleIterator} in order to decode
* the entry.
*/
@SuppressWarnings("unchecked")
public E first() {
final IIndex ndx = map.getIndex();
final ITupleIterator itr = ndx.rangeIterator(map.fromKey, map.toKey,
1/* capacity */, IRangeQuery.DEFAULT, null/* filter */);
if(!itr.hasNext()) {
throw new NoSuchElementException();
}
return (E) map.tupleSer.deserialize(itr.next());
}
/**
* Note: This is written using an {@link ITupleIterator} in order to decode
* the entry.
*/
@SuppressWarnings("unchecked")
public E last() {
final IIndex ndx = map.getIndex();
final ITupleIterator itr = ndx.rangeIterator(map.fromKey, map.toKey,
1/* capacity */, IRangeQuery.DEFAULT|IRangeQuery.REVERSE, null/* filter */);
if(!itr.hasNext()) {
throw new NoSuchElementException();
}
return (E) map.tupleSer.deserialize(itr.next());
}
public SortedSet headSet(E toKey) {
return new BigdataSet((BigdataMap) map.headMap(toKey));
}
public SortedSet subSet(E fromKey, E toKey) {
return new BigdataSet((BigdataMap) map.subMap(fromKey, toKey));
}
public SortedSet tailSet(E fromKey) {
return new BigdataSet((BigdataMap) map.tailMap(fromKey));
}
}