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TDB is a storage subsystem for Jena and ARQ, it is a native triple store providing persistent storage of triples/quads.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
package org.apache.jena.tdb.lib;
import static org.apache.jena.tdb.sys.SystemTDB.LenNodeHash ;
import java.nio.ByteBuffer ;
import java.security.DigestException ;
import java.security.MessageDigest ;
import java.security.NoSuchAlgorithmException ;
import java.util.Iterator ;
import org.apache.jena.atlas.iterator.Iter ;
import org.apache.jena.atlas.lib.Bytes ;
import org.apache.jena.atlas.lib.Pool ;
import org.apache.jena.atlas.lib.PoolBase ;
import org.apache.jena.atlas.lib.PoolSync ;
import org.apache.jena.atlas.logging.Log ;
import org.apache.jena.graph.Node ;
import org.apache.jena.sparql.util.NodeUtils ;
import org.apache.jena.tdb.TDBException ;
import org.apache.jena.tdb.base.objectfile.ObjectFile ;
import org.apache.jena.tdb.base.record.Record ;
import org.apache.jena.tdb.store.Hash ;
import org.apache.jena.tdb.store.NodeId ;
import org.apache.jena.tdb.store.NodeType ;
import org.apache.jena.tdb.store.nodetable.NodeTable ;
import org.apache.jena.tdb.store.nodetable.Nodec ;
import org.apache.jena.tdb.store.nodetable.NodecSSE ;
public class NodeLib
{
private static Nodec nodec = new NodecSSE() ;
/**
* Encode and write a {@link Node} to the {@link ObjectFile}. Returns the location,
* suitable for use with {@link #fetchDecode}.
*/
public static long encodeStore(Node node, ObjectFile file) {
return encodeStore(node, file, null);
}
/**
* Encode and write a {@link Node} to the {@link ObjectFile}.
* Uses the given {@link ByteBuffer} for encoding space if possible.
* Returns the location, suitable for use with {@link #fetchDecode}.
*/
public static long encodeStore(Node node, ObjectFile file, ByteBuffer bb) {
int maxSize = nodec.maxSize(node);
if ( bb == null )
return allocEncodeWrite(node, file, maxSize);
if ( bb.capacity() < maxSize )
// Buffer may not be big enough.
return allocEncodeWrite(node, file, maxSize);
// Use buffer provided.
bb.clear();
return encodeWrite(node, file, bb);
}
/** Encode and write, allocating space as needed */
private static long allocEncodeWrite(Node node, ObjectFile file, int maxSize) {
ByteBuffer bb = ByteBuffer.allocate(maxSize);
return encodeWrite(node, file, bb);
}
/** Encode and write, using the space provided which is assumed to be large enough. */
private static long encodeWrite(Node node, ObjectFile file, ByteBuffer bb) {
int len = nodec.encode(node, bb, null);
long x = file.write(bb);
return x;
}
/**
* Read and decode a {@link Node} from the {@link ObjectFile}. The {@code id} must
* have originally been generated by {@link #encodeStore}.
*/
public static Node fetchDecode(long id, ObjectFile file) {
ByteBuffer bb = file.read(id);
if ( bb == null )
return null;
return decode(bb);
}
/**
* Encode a node - it is better to use encodeStore which may avoid an additional copy
* in getting the node into the ObjectFile and may avoid short-term byte buffer
* allocation.
*/
public static ByteBuffer encode(Node node) {
int maxSize = nodec.maxSize(node);
ByteBuffer bb = ByteBuffer.allocate(maxSize);
int len = nodec.encode(node, bb, null);
bb.limit(len);
bb.position(0);
return bb;
}
/**
* Decode a node - it is better to use fetchDecode which may avoid an additional copy
* in getting the node from the ObjectFile.
*/
public static Node decode(ByteBuffer bb) {
bb.position(0);
Node n = nodec.decode(bb, null);
return n;
}
public static Hash hash(Node n) {
Hash h = new Hash(LenNodeHash);
setHash(h, n);
return h;
}
public static void setHash(Hash h, Node n) {
NodeType nt = NodeType.lookup(n);
switch (nt) {
case URI :
hash(h, n.getURI(), null, null, nt);
return;
case BNODE :
hash(h, n.getBlankNodeLabel(), null, null, nt);
return;
case LITERAL :
String dt = n.getLiteralDatatypeURI();
if ( NodeUtils.isSimpleString(n) || NodeUtils.isLangString(n) ) {
// RDF 1.1 : No datatype for:
// xsd:String as simple literals
// rdf:langString and @
dt = null;
}
hash(h, n.getLiteralLexicalForm(), n.getLiteralLanguage(), dt, nt);
return;
case OTHER :
throw new TDBException("Attempt to hash something strange: " + n);
}
throw new TDBException("NodeType broken: " + n);
}
private static int InitialPoolSize = 5;
private static Pool digesters = PoolSync.create(new PoolBase());
static {
try {
for ( int i = 0 ; i < InitialPoolSize ; i++ )
digesters.put(MessageDigest.getInstance("MD5"));
}
catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
}
private static MessageDigest allocDigest() {
try {
MessageDigest disgest = digesters.get();
if ( disgest == null )
disgest = MessageDigest.getInstance("MD5");
return disgest;
}
catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return null;
}
}
private static void deallocDigest(MessageDigest digest) {
digest.reset();
digesters.put(digest);
}
private static void hash(Hash h, String lex, String lang, String datatype, NodeType nodeType) {
if ( datatype == null )
datatype = "";
if ( lang == null )
lang = "";
String toHash = lex + "|" + lang + "|" + datatype + "|" + nodeType.getName();
MessageDigest digest;
try {
digest = allocDigest();
digest.update(Bytes.string2bytes(toHash));
if ( h.getLen() == 16 )
// MD5 is 16 bytes.
digest.digest(h.getBytes(), 0, 16);
else {
byte b[] = digest.digest(); // 16 bytes.
// Avoid the copy if length is 16?
// digest.digest(bytes, 0, length) needs 16 bytes
System.arraycopy(b, 0, h.getBytes(), 0, h.getLen());
}
deallocDigest(digest);
return;
}
catch (DigestException ex) {
Log.error(NodeLib.class, "DigestException", ex);
}
}
public static NodeId getNodeId(Record r, int idx) {
return NodeId.create(Bytes.getLong(r.getKey(), idx));
}
public static Node termOrAny(Node node) {
if ( node == null || node.isVariable() )
return Node.ANY;
return node;
}
public static Iterator nodes(final NodeTable nodeTable, Iterator iter) {
return Iter.map(iter, nodeTable::getNodeForNodeId);
}
}