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// 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.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.Mapper;
import org.janusgraph.diskstorage.Entry;
import org.janusgraph.diskstorage.EntryList;
import org.janusgraph.diskstorage.StaticBuffer;
import org.janusgraph.diskstorage.configuration.ConfigNamespace;
import org.janusgraph.diskstorage.configuration.Configuration;
import org.janusgraph.diskstorage.configuration.ModifiableConfiguration;
import org.janusgraph.diskstorage.keycolumnvalue.SliceQuery;
import org.janusgraph.diskstorage.keycolumnvalue.scan.ScanJob;
import org.janusgraph.diskstorage.util.BufferUtil;
import org.janusgraph.diskstorage.util.EntryArrayList;
import org.janusgraph.hadoop.config.JanusGraphHadoopConfiguration;
import org.janusgraph.hadoop.config.ModifiableHadoopConfiguration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.function.Predicate;
/**
* Run a {@link org.janusgraph.diskstorage.keycolumnvalue.scan.ScanJob}
* via a Hadoop {@link org.apache.hadoop.mapreduce.Mapper} over the edgestore.
*/
public class HadoopScanMapper extends Mapper, NullWritable, NullWritable> {
private static final Logger log = LoggerFactory.getLogger(HadoopScanMapper.class);
protected ScanJob job;
protected HadoopContextScanMetrics metrics;
protected org.janusgraph.diskstorage.configuration.Configuration jobConf;
private Predicate keyFilter;
private SliceQuery initialQuery;
private List subsequentQueries;
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
org.apache.hadoop.conf.Configuration hadoopConf = context.getConfiguration();
ModifiableHadoopConfiguration scanConf = ModifiableHadoopConfiguration.of(JanusGraphHadoopConfiguration.MAPRED_NS, hadoopConf);
job = getJob(scanConf);
metrics = new HadoopContextScanMetrics(context);
Configuration graphConf = getJanusGraphConfiguration(context);
finishSetup(scanConf, graphConf);
}
protected void finishSetup(ModifiableHadoopConfiguration scanConf, Configuration graphConf) {
jobConf = getJobConfiguration(scanConf);
Preconditions.checkNotNull(metrics);
// Allowed to be null for jobs that specify no configuration and no configuration root
//Preconditions.checkNotNull(jobConf);
Preconditions.checkNotNull(job);
job.workerIterationStart(jobConf, graphConf, metrics);
keyFilter = job.getKeyFilter();
List sliceQueries = job.getQueries();
Preconditions.checkArgument(null != sliceQueries, "Job cannot specify null query list");
Preconditions.checkArgument(0 < sliceQueries.size(), "Job must specify at least one query");
// Assign head of getQueries() to "initialQuery"
initialQuery = sliceQueries.get(0);
// Assign tail of getQueries() to "subsequentQueries"
subsequentQueries = new ArrayList<>(sliceQueries.subList(1,sliceQueries.size()));
Preconditions.checkState(sliceQueries.size() == subsequentQueries.size() + 1);
Preconditions.checkNotNull(initialQuery);
if (0 < subsequentQueries.size()) {
//It is assumed that the first query is the grounding query if multiple queries exist
StaticBuffer start = initialQuery.getSliceStart();
Preconditions.checkArgument(start.equals(BufferUtil.zeroBuffer(1)),
"Expected start of first query to be all 0s: %s", start);
StaticBuffer end = initialQuery.getSliceEnd();
Preconditions.checkArgument(end.equals(BufferUtil.oneBuffer(end.length())),
"Expected end of first query to be all 1s: %s", end);
}
}
@Override
protected void map(StaticBuffer key, Iterable values, Context context) throws IOException, InterruptedException {
EntryArrayList al = EntryArrayList.of(values);
// KeyFilter check
if (!keyFilter.test(key)) {
log.debug("Skipping key {} based on KeyFilter", key);
return;
}
// InitialQuery check (at least one match is required or else the key is ignored)
EntryList initialQueryMatches = findEntriesMatchingQuery(initialQuery, al);
if (0 == initialQueryMatches.size()) {
log.debug("Skipping key {} based on InitialQuery ({}) match failure", key, initialQuery);
return;
}
// Both conditions (KeyFilter && InitialQuery) for invoking process are satisfied
// Create an entries parameter to be passed into the process method
Map matches = new HashMap<>();
matches.put(initialQuery, initialQueryMatches);
// Find matches (if any are present) for subsequent queries
for (SliceQuery sq : subsequentQueries) {
matches.put(sq, findEntriesMatchingQuery(sq, al));
}
// Process
job.process(key, matches, metrics);
}
@Override
protected void cleanup(Context context) throws IOException, InterruptedException {
super.cleanup(context);
job.workerIterationEnd(metrics);
}
private EntryList findEntriesMatchingQuery(SliceQuery query, EntryList sortedEntries) {
int lowestStartMatch = sortedEntries.size(); // Inclusive
int highestEndMatch = -1; // Inclusive
final StaticBuffer queryStart = query.getSliceStart();
final StaticBuffer queryEnd = query.getSliceEnd();
// Find the lowest matchStart s.t. query.getSliceStart <= sortedEntries.get(matchStart)
int low = 0;
int high = sortedEntries.size() - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
Entry midVal = sortedEntries.get(mid);
int cmpStart = queryStart.compareTo(midVal.getColumn());
if (0 < cmpStart) {
// query lower bound exceeds entry (no match)
if (lowestStartMatch == mid + 1) {
// lowestStartMatch located
break;
}
// Move to higher list index
low = mid + 1;
} else /* (0 >= cmpStart) */ {
// entry equals or exceeds query lower bound (match, but not necessarily lowest match)
if (mid < lowestStartMatch) {
lowestStartMatch = mid;
}
// Move to a lower list index
high = mid - 1;
}
}
// If lowestStartMatch is beyond the end of our list parameter, there cannot possibly be any matches,
// so we can bypass the highestEndMatch search and just return an empty result.
if (sortedEntries.size() == lowestStartMatch) {
return EntryList.EMPTY_LIST;
}
// Find the highest matchEnd s.t. sortedEntries.get(matchEnd) < query.getSliceEnd
low = 0;
high = sortedEntries.size() - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
Entry midVal = sortedEntries.get(mid);
int cmpEnd = queryEnd.compareTo(midVal.getColumn());
if (0 < cmpEnd) {
// query upper bound exceeds entry (match, not necessarily highest)
if (mid > highestEndMatch) {
highestEndMatch = mid;
}
// Move to higher list index
low = mid + 1;
} else /* (0 >= cmpEnd) */ {
// entry equals or exceeds query upper bound (no match)
if (highestEndMatch == mid - 1) {
// highestEndMatch located
break;
}
// Move to a lower list index
high = mid - 1;
}
}
if (0 <= highestEndMatch - lowestStartMatch) {
// Return sublist between indices (inclusive at both indices)
int endIndex = highestEndMatch + 1; // This will be passed into subList, which interprets it exclusively
if (query.hasLimit()) {
endIndex = Math.min(endIndex, query.getLimit() + lowestStartMatch);
}
// TODO avoid unnecessary copy here
return EntryArrayList.of(sortedEntries.subList(lowestStartMatch, endIndex /* exclusive */));
} else {
return EntryList.EMPTY_LIST;
}
}
private ScanJob getJob(Configuration scanConf) {
String jobClass = scanConf.get(JanusGraphHadoopConfiguration.SCAN_JOB_CLASS);
try {
return (ScanJob)Class.forName(jobClass).newInstance();
} catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
throw new RuntimeException(e);
}
}
static ModifiableConfiguration getJanusGraphConfiguration(Context context) {
org.apache.hadoop.conf.Configuration hadoopConf = context.getConfiguration();
return ModifiableHadoopConfiguration.of(JanusGraphHadoopConfiguration.MAPRED_NS, hadoopConf).getJanusGraphConf();
}
static Configuration getJobConfiguration(ModifiableHadoopConfiguration scanConf) {
if (!scanConf.has(JanusGraphHadoopConfiguration.SCAN_JOB_CONFIG_ROOT)) {
log.debug("No job configuration root provided");
return null;
}
ConfigNamespace jobRoot = getJobRoot(scanConf.get(JanusGraphHadoopConfiguration.SCAN_JOB_CONFIG_ROOT));
return ModifiableHadoopConfiguration.prefixView(jobRoot, JanusGraphHadoopConfiguration.SCAN_JOB_CONFIG_KEYS,
scanConf);
}
static ConfigNamespace getJobRoot(String confRootName) {
String[] tokens = confRootName.split("#");
String className = tokens[0];
String fieldName = tokens[1];
try {
Field f = Class.forName(className).getField(fieldName);
return (ConfigNamespace)f.get(null);
} catch (NoSuchFieldException | ClassNotFoundException | IllegalAccessException e) {
throw new RuntimeException(e);
}
}
}
