// Copyright 2017 JanusGraph Authors
//
// 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.
package org.janusgraph.hadoop.scan;
import com.google.common.base.Preconditions;
import org.janusgraph.diskstorage.configuration.*;
import org.janusgraph.diskstorage.configuration.Configuration;
import org.janusgraph.diskstorage.keycolumnvalue.scan.ScanJob;
import org.janusgraph.diskstorage.keycolumnvalue.scan.ScanMetrics;
import org.janusgraph.graphdb.olap.VertexScanJob;
import org.janusgraph.hadoop.compat.HadoopCompatLoader;
import org.janusgraph.hadoop.config.ModifiableHadoopConfiguration;
import org.janusgraph.hadoop.config.JanusGraphHadoopConfiguration;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.output.NullOutputFormat;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.Map;
import static org.janusgraph.hadoop.compat.HadoopCompatLoader.DEFAULT_COMPAT;
/**
* Utility class to construct and submit Hadoop Jobs that execute a {@link HadoopScanMapper}.
*/
public class HadoopScanRunner {
private static final Logger log =
LoggerFactory.getLogger(HadoopScanRunner.class);
/**
* Run a ScanJob on Hadoop MapReduce.
* <p>
* The {@code confRootField} parameter must be a string in the format
* {@code package.package...class#fieldname}, where {@code fieldname} is the
* name of a public static field on the class specified by the portion of the
* string before the {@code #}. The {@code #} itself is just a separator and
* is discarded.
* <p>
* When a MapReduce task process prepares to execute the {@code ScanJob}, it will
* read the public static field named by {@code confFieldRoot} and cast it to a
* {@link ConfigNamespace}. This namespace object becomes the root of a
* {@link Configuration} instantiated, populated with the key-value pairs
* from the {@code conf} parameter, and then passed into the {@code ScanJob}.
* <p>
* This method blocks until the ScanJob completes, then returns the metrics
* generated by the job during its execution. It does not timeout.
*
* @param conf configuration settings for the ScanJob
* @param confRootField the root of the ScanJob's configuration
* @param hadoopConf the Configuration passed to the MapReduce Job
* @param inputFormat the InputFormat<StaticBuffer, Iterable<Entry>>
* that reads (row, columns) pairs out of a JanusGraph edgestore
* @return metrics generated by the ScanJob
* @throws IOException if the job fails for any reason
* @throws ClassNotFoundException if {@code scanJob.getClass()} or if Hadoop
* MapReduce's internal job-submission-related reflection fails
* @throws InterruptedException if interrupted while waiting for the Hadoop
* MapReduce job to complete
*/
public static ScanMetrics runJob(Configuration conf, String confRootField,
org.apache.hadoop.conf.Configuration hadoopConf,
Class<? extends InputFormat> inputFormat, String jobName,
Class<? extends Mapper> mapperClass)
throws IOException, InterruptedException, ClassNotFoundException {
Preconditions.checkArgument(null != hadoopConf);
Preconditions.checkArgument(null != inputFormat);
if (null != conf) {
Preconditions.checkArgument(null != confRootField,
"Configuration root field must be provided when configuration instance is provided");
}
ModifiableHadoopConfiguration scanConf =
ModifiableHadoopConfiguration.of(JanusGraphHadoopConfiguration.MAPRED_NS, hadoopConf);
if (null != confRootField) {
// Set the scanjob configuration root
scanConf.set(JanusGraphHadoopConfiguration.SCAN_JOB_CONFIG_ROOT, confRootField);
// Instantiate scanjob configuration root
ConfigNamespace confRoot = HadoopScanMapper.getJobRoot(confRootField);
// Create writable view of scanjob configuration atop the Hadoop Configuration instance, where all keys are prefixed with SCAN_JOB_CONFIG_KEYS
ModifiableConfiguration hadoopJobConf = ModifiableHadoopConfiguration.prefixView(confRoot,
JanusGraphHadoopConfiguration.SCAN_JOB_CONFIG_KEYS, scanConf);
// Copy scanjob settings from the JanusGraph Configuration instance to the Hadoop Configuration instance
Map<String, Object> jobConfMap = conf.getSubset(confRoot);
for (Map.Entry<String, Object> jobConfEntry : jobConfMap.entrySet()) {
hadoopJobConf.set((ConfigOption) ConfigElement.parse(confRoot, jobConfEntry.getKey()).element, jobConfEntry.getValue());
}
}
return runJob(scanConf.getHadoopConfiguration(), inputFormat, jobName, mapperClass);
}
public static ScanMetrics runJob(org.apache.hadoop.conf.Configuration hadoopConf,
Class<? extends InputFormat> inputFormat, String jobName,
Class<? extends Mapper> mapperClass)
throws IOException, InterruptedException, ClassNotFoundException {
Job job = Job.getInstance(hadoopConf);
//job.setJarByClass(HadoopScanMapper.class);
job.setJarByClass(mapperClass);
//job.setJobName(HadoopScanMapper.class.getSimpleName() + "[" + scanJob + "]");
job.setJobName(jobName);
job.setOutputKeyClass(NullWritable.class);
job.setOutputValueClass(NullWritable.class);
job.setMapOutputKeyClass(NullWritable.class);
job.setMapOutputValueClass(NullWritable.class);
job.setNumReduceTasks(0);
//job.setMapperClass(HadoopScanMapper.class);
job.setMapperClass(mapperClass);
job.setOutputFormatClass(NullOutputFormat.class);
job.setInputFormatClass(inputFormat);
boolean success = job.waitForCompletion(true);
if (!success) {
String f;
try {
// Just in case one of Job's methods throws an exception
f = String.format("MapReduce JobID %s terminated abnormally: %s",
job.getJobID().toString(), HadoopCompatLoader.DEFAULT_COMPAT.getJobFailureString(job));
} catch (RuntimeException e) {
f = "Job failed (unable to read job status programmatically -- see MapReduce logs for information)";
}
throw new IOException(f);
} else {
return DEFAULT_COMPAT.getMetrics(job.getCounters());
}
}
public static ScanMetrics runScanJob(ScanJob scanJob, Configuration conf, String confRootField,
org.apache.hadoop.conf.Configuration hadoopConf,
Class<? extends InputFormat> inputFormat)
throws IOException, InterruptedException, ClassNotFoundException {
ModifiableHadoopConfiguration scanConf =
ModifiableHadoopConfiguration.of(JanusGraphHadoopConfiguration.MAPRED_NS, hadoopConf);
tryToLoadClassByName(scanJob);
// Set the ScanJob class
scanConf.set(JanusGraphHadoopConfiguration.SCAN_JOB_CLASS, scanJob.getClass().getName());
String jobName = HadoopScanMapper.class.getSimpleName() + "[" + scanJob + "]";
return runJob(conf, confRootField, hadoopConf, inputFormat, jobName, HadoopScanMapper.class);
}
public static ScanMetrics runVertexScanJob(VertexScanJob vertexScanJob, Configuration conf, String confRootField,
org.apache.hadoop.conf.Configuration hadoopConf,
Class<? extends InputFormat> inputFormat)
throws IOException, InterruptedException, ClassNotFoundException {
ModifiableHadoopConfiguration scanConf =
ModifiableHadoopConfiguration.of(JanusGraphHadoopConfiguration.MAPRED_NS, hadoopConf);
tryToLoadClassByName(vertexScanJob);
// Set the VertexScanJob class
scanConf.set(JanusGraphHadoopConfiguration.SCAN_JOB_CLASS, vertexScanJob.getClass().getName());
String jobName = HadoopScanMapper.class.getSimpleName() + "[" + vertexScanJob + "]";
return runJob(conf, confRootField, hadoopConf, inputFormat, jobName, HadoopVertexScanMapper.class);
}
private static void tryToLoadClassByName(Object o) throws ClassNotFoundException {
// Test that we can find this ScanJob class by its name; better to detect a problem here than in the mappers
String scanJobClassname = o.getClass().getName();
try {
Class.forName(scanJobClassname);
} catch (ClassNotFoundException e) {
log.error("Unable to locate class with name {}", scanJobClassname, e);
throw e;
}
}
}