/*
* 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.hadoop.rdf.io.input.util;
import java.util.UUID;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.jena.hadoop.rdf.io.RdfIOConstants;
import org.apache.jena.riot.lang.LabelToNode;
import org.apache.jena.riot.system.* ;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* RDF IO utility functions
*
*
*
*/
public class RdfIOUtils {
private static final Logger LOGGER = LoggerFactory.getLogger(RdfIOUtils.class);
/**
* Private constructor prevents instantiation
*/
private RdfIOUtils() {
}
/**
* Creates a parser profile for the given job context
*
* @param context
* Context
* @param path
* File path
* @return Parser profile
*/
public static ParserProfile createParserProfile(JobContext context, Path path) {
Prologue prologue = new Prologue(PrefixMapFactory.createForInput(), IRIResolver.createNoResolve());
UUID seed = RdfIOUtils.getSeed(context, path);
LabelToNode labelMapping = LabelToNode.createScopeByDocumentHash(seed);
return new ParserProfileBase(prologue, ErrorHandlerFactory.errorHandlerStd, RiotLib.factoryRDF(labelMapping));
}
/**
* Selects a seed for use in generating blank node identifiers
*
* @param context
* Job Context
* @param path
* File path
* @return Seed
*/
public static UUID getSeed(JobContext context, Path path) {
// This is to ensure that blank node allocation policy is constant when
// subsequent MapReduce jobs need that
String jobId = context.getJobID().toString();
if (jobId == null) {
jobId = String.valueOf(System.currentTimeMillis());
LOGGER.warn(
"Job ID was not set, using current milliseconds of {}. Sequence of MapReduce jobs must carefully handle blank nodes.",
jobId);
}
if (!context.getConfiguration().getBoolean(RdfIOConstants.GLOBAL_BNODE_IDENTITY, false)) {
// Using normal file scoped blank node allocation
LOGGER.debug("Generating Blank Node Seed from Job Details (ID={}, Input Path={})", jobId, path);
// Form a reproducible seed for the run
return new UUID(jobId.hashCode(), path.hashCode());
} else {
// Using globally scoped blank node allocation
LOGGER.warn(
"Using globally scoped blank node allocation policy from Job Details (ID={}) - this is unsafe if your RDF inputs did not originate from a previous job",
jobId);
return new UUID(jobId.hashCode(), 0);
}
}
}