com.bigdata.rdf.lexicon.Id2TermTupleSerializer 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 Jul 7, 2008
*/
package com.bigdata.rdf.lexicon;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import org.openrdf.model.Value;
import com.bigdata.btree.DefaultTupleSerializer;
import com.bigdata.btree.ITuple;
import com.bigdata.btree.keys.ASCIIKeyBuilderFactory;
import com.bigdata.btree.keys.IKeyBuilderFactory;
import com.bigdata.btree.raba.codec.IRabaCoder;
import com.bigdata.btree.raba.codec.SimpleRabaCoder;
import com.bigdata.io.ByteArrayBuffer;
import com.bigdata.io.DataOutputBuffer;
import com.bigdata.rdf.internal.IV;
import com.bigdata.rdf.internal.IVUtility;
import com.bigdata.rdf.internal.impl.TermId;
import com.bigdata.rdf.model.BigdataValue;
import com.bigdata.rdf.model.BigdataValueFactory;
import com.bigdata.rdf.model.BigdataValueFactoryImpl;
import com.bigdata.rdf.model.BigdataValueSerializer;
import com.bigdata.rdf.store.AbstractTripleStore;
import com.bigdata.util.Bytes;
/**
* Encapsulates key and value formation for the reverse lexicon index.
*
* @author Bryan Thompson
* @version $Id$
*/
public class Id2TermTupleSerializer extends DefaultTupleSerializer {
/**
*
*/
private static final long serialVersionUID = 4841769875819006615L;
/**
* The namespace of the owning {@link LexiconRelation}.
*/
private String namespace;
/**
* A (de-)serialized backed by a {@link BigdataValueFactoryImpl} for the
* {@link #namespace} of the owning {@link LexiconRelation}.
*/
transient private BigdataValueSerializer valueSer;
private static transient final int INITIAL_CAPACITY = 128;
/**
* Used to serialize RDF {@link Value}s.
*
* Note: While this object is not thread-safe, the mutable B+Tree is
* restricted to a single writer so it does not have to be thread-safe.
*/
final transient private DataOutputBuffer buf = new DataOutputBuffer(INITIAL_CAPACITY);
/**
* Used to serialize RDF {@link Value}s.
*
* Note: While this object is not thread-safe, the mutable B+Tree is
* restricted to a single writer so it does not have to be thread-safe.
*/
final transient private ByteArrayBuffer tbuf = new ByteArrayBuffer(INITIAL_CAPACITY);
transient private BigdataValueFactory valueFactory;
/**
* De-serialization ctor.
*/
public Id2TermTupleSerializer() {
super();
}
/**
*
* @param keyBuilderFactory
* A factory that does not support unicode and has an
* initialCapacity of {@value Bytes#SIZEOF_LONG}.
*/
public Id2TermTupleSerializer(final String namespace,
final BigdataValueFactory valueFactory) {
this(namespace,valueFactory,
// Note: TermId is now 9 bytes (flags + tid)
new ASCIIKeyBuilderFactory(Bytes.SIZEOF_LONG+1),//
getDefaultLeafKeysCoder(),//
// getDefaultValuesCoder() // Canonical Huffman coding.
SimpleRabaCoder.INSTANCE // Much faster
);
}
public Id2TermTupleSerializer(final String namespace,
final BigdataValueFactory valueFactory,
final IKeyBuilderFactory keyBuilderFactory,
final IRabaCoder leafKeysCoder, final IRabaCoder leafValsCoder) {
super(keyBuilderFactory, leafKeysCoder, leafValsCoder);
if (namespace == null)
throw new IllegalArgumentException();
this.namespace = namespace;
this.valueFactory = valueFactory;
this.valueSer = this.valueFactory.getValueSerializer();
}
/**
* Generates an unsigned byte[] key from a {@link TermId}.
*
* Note: The code that handles efficient batch insertion of terms into the
* database replicates the logic for encoding the term identifier as an
* unsigned long integer.
*
* @param id
* The term identifier.
*
* @return The id expressed as an unsigned byte[] key of length 8.
*
* @see #key2Id()
*/
public byte[] id2key(final TermId tid) {
return tid.encode(getKeyBuilder().reset()).getKey();
}
/**
* Decodes the term identifier key to a term identifier.
*
* @param key
* The key for an entry in the id:term index.
*
* @return The term identifier.
*/
public IV deserializeKey(final ITuple tuple) {
final byte[] key = tuple.getKeyBuffer().array();
return IVUtility.decode(key);
}
/**
* Return the unsigned byte[] key for a term identifier.
*
* @param obj
* The term identifier as a {@link TermId}.
*/
public byte[] serializeKey(final Object obj) {
return id2key((TermId) obj);
}
/**
* Return the byte[] value, which is the serialization of an
* RDF {@link Value}.
*
* @param obj
* An RDF {@link Value}.
*/
public byte[] serializeVal(final BigdataValue obj) {
return valueSer.serialize(obj, buf.reset(), tbuf);
}
/**
* De-serializes the {@link ITuple} as a {@link BigdataValue}, including
* the term identifier extracted from the unsigned byte[] key, and sets
* the appropriate {@link BigdataValueFactoryImpl} reference on that object.
*/
public BigdataValue deserialize(final ITuple tuple) {
final IV iv = deserializeKey(tuple);
final BigdataValue tmp = valueSer.deserialize(tuple.getValueStream(),
new StringBuilder());
tmp.setIV(iv);
return tmp;
}
/**
*
* valueFactoryClass:UTF
* namespace:UTF
*
*/
private static final transient byte VERSION0 = 0;
private static final transient byte VERSION = VERSION0;
public void readExternal(final ObjectInput in) throws IOException, ClassNotFoundException {
super.readExternal(in);
final byte version = in.readByte();
final String namespace;
final String valueFactoryClass;
switch (version) {
case VERSION0:
namespace = in.readUTF();
valueFactoryClass = in.readUTF();
break;
default:
throw new IOException("unknown version=" + version);
}
// set the namespace field.
this.namespace = namespace;
// resolve the valueSerializer from the value factory class.
try {
final Class vfc = Class.forName(valueFactoryClass);
if (!BigdataValueFactory.class.isAssignableFrom(vfc)) {
throw new RuntimeException(
AbstractTripleStore.Options.VALUE_FACTORY_CLASS
+ ": Must extend: "
+ BigdataValueFactory.class.getName());
}
final Method gi = vfc.getMethod("getInstance", String.class);
this.valueFactory = (BigdataValueFactory) gi
.invoke(null, namespace);
} catch (NoSuchMethodException e) {
throw new IOException(e);
} catch (InvocationTargetException e) {
throw new IOException(e);
} catch (IllegalAccessException e) {
throw new IOException(e);
}
valueSer = this.valueFactory.getValueSerializer();
}
public void writeExternal(final ObjectOutput out) throws IOException {
super.writeExternal(out);
out.writeByte(VERSION);
out.writeUTF(namespace);
out.writeUTF(valueFactory.getClass().getName());
}
}