org.cloudgraph.hbase.mapreduce.GraphMapReduceSetup.java Source code

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/**
 * Copyright 2017 TerraMeta Software, Inc.
 * 
 * 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.cloudgraph.hbase.mapreduce;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

import javax.xml.bind.JAXBException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.FilterList;
import org.apache.hadoop.hbase.filter.RandomRowFilter;
import org.apache.hadoop.hbase.mapreduce.JarFinder;
import org.apache.hadoop.hbase.mapreduce.TableOutputFormat;
//import org.apache.hadoop.hbase.mapreduce.TableOutputFormat;
import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
import org.apache.hadoop.hbase.protobuf.generated.ClientProtos;
//import org.apache.hadoop.hbase.mapreduce.hadoopbackport.JarFinder;
import org.apache.hadoop.hbase.security.User;
import org.apache.hadoop.hbase.security.UserProvider;
import org.apache.hadoop.hbase.security.token.TokenUtil;
import org.apache.hadoop.hbase.util.Base64;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.util.StringUtils;
import org.cloudgraph.hbase.filter.GraphFetchColumnFilterAssembler;
import org.cloudgraph.hbase.filter.HBaseFilterAssembler;
import org.cloudgraph.hbase.io.DistributedGraphReader;
import org.cloudgraph.hbase.scan.CompleteRowKey;
import org.cloudgraph.hbase.scan.FuzzyRowKey;
import org.cloudgraph.hbase.scan.PartialRowKey;
import org.cloudgraph.hbase.scan.PartialRowKeyScanAssembler;
import org.cloudgraph.hbase.scan.ScanCollector;
import org.cloudgraph.hbase.scan.ScanRecognizerSyntaxTreeAssembler;
import org.cloudgraph.hbase.util.FilterUtil;
import org.cloudgraph.job.JobSetup;
import org.cloudgraph.query.expr.Expr;
import org.cloudgraph.query.expr.ExprPrinter;
import org.cloudgraph.store.mapping.Config;
import org.cloudgraph.store.mapping.DataGraphMapping;
import org.cloudgraph.store.mapping.DataRowKeyFieldMapping;
import org.cloudgraph.store.mapping.StoreMapping;
import org.cloudgraph.store.service.GraphServiceException;
import org.plasma.common.bind.DefaultValidationEventHandler;
import org.plasma.query.From;
import org.plasma.query.Query;
import org.plasma.query.bind.PlasmaQueryDataBinding;
import org.plasma.query.collector.SelectionCollector;
import org.plasma.query.model.Where;
import org.plasma.sdo.PlasmaType;
import org.xml.sax.SAXException;

import com.google.protobuf.InvalidProtocolBufferException;
import commonj.sdo.Type;

/**
 * Mapreduce Job setup utility for {@link GraphMapper} and {@link GraphReducer}
 * and extensions.
 */
@SuppressWarnings("unchecked")
public class GraphMapReduceSetup extends JobSetup {
    static Log LOG = LogFactory.getLog(GraphMapReduceSetup.class);

    /**
     * Use this before submitting a graph map job. It will appropriately set up
     * the job.
     * 
     * @param query
     *          The query defining the {@link GraphMapper} input graphs.
     * @param mapper
     *          The mapper class to use.
     * @param outputKeyClass
     *          The class of the output key.
     * @param outputValueClass
     *          The class of the output value.
     * @param job
     *          The current job to adjust. Make sure the passed job is carrying
     *          all necessary HBase configuration.
     * @throws IOException
     *           When setting up the details fails.
     */
    public static void setupGraphMapperJob(Query query, Class<? extends GraphMapper> mapper,
            Class<? extends WritableComparable> outputKeyClass, Class<? extends Writable> outputValueClass, Job job)
            throws IOException {
        setupGraphMapperJob(query, mapper, outputKeyClass, outputValueClass, job, true);
    }

    /**
     * Use this before submitting a graph map job. It will appropriately set up
     * the job.
     * 
     * @param query
     *          The query defining the {@link GraphMapper} input graphs.
     * @param mapper
     *          The mapper class to use.
     * @param outputKeyClass
     *          The class of the output key.
     * @param outputValueClass
     *          The class of the output value.
     * @param job
     *          The current job to adjust. Make sure the passed job is carrying
     *          all necessary HBase configuration.
     * @param addDependencyJars
     *          upload HBase jars and jars for any of the configured job classes
     *          via the distributed cache (tmpjars).
     * @throws IOException
     *           When setting up the details fails.
     */
    public static void setupGraphMapperJob(Query query, Class<? extends GraphMapper> mapper,
            Class<? extends WritableComparable> outputKeyClass, Class<? extends Writable> outputValueClass, Job job,
            boolean addDependencyJars, Class<? extends InputFormat> inputFormatClass) throws IOException {
        job.setInputFormatClass(inputFormatClass);
        if (outputValueClass != null)
            job.setMapOutputValueClass(outputValueClass);
        if (outputKeyClass != null)
            job.setMapOutputKeyClass(outputKeyClass);
        job.setMapperClass(mapper);
        Configuration conf = job.getConfiguration();
        HBaseConfiguration.merge(conf, HBaseConfiguration.create(conf));

        PlasmaType type = getRootType(query);

        Where where = query.getModel().findWhereClause();
        SelectionCollector selectionCollector = null;
        if (where != null)
            selectionCollector = new SelectionCollector(query.getModel().getSelectClause(), where, type);
        else
            selectionCollector = new SelectionCollector(query.getModel().getSelectClause(), type);
        selectionCollector.setOnlyDeclaredProperties(false);
        // FIXME: generalize collectRowKeyProperties
        for (Type t : selectionCollector.getTypes())
            collectRowKeyProperties(selectionCollector, (PlasmaType) t);

        // FIXME: just need the root table reader - remove
        DistributedGraphReader graphReader = new DistributedGraphReader(type, selectionCollector.getTypes(), null);

        HBaseFilterAssembler columnFilterAssembler = new GraphFetchColumnFilterAssembler(selectionCollector, type);
        Filter columnFilter = columnFilterAssembler.getFilter();

        From from = query.getModel().getFromClause();
        List<Scan> scans = createScans(from, where, type, columnFilter, conf);

        conf.set(GraphInputFormat.QUERY, marshal(query));
        conf.set(GraphInputFormat.ROOT_TABLE, graphReader.getRootTableReader().getTableName());

        List<String> scanStrings = new ArrayList<String>();

        for (Scan scan : scans) {
            scan.setAttribute(Scan.SCAN_ATTRIBUTES_TABLE_NAME,
                    Bytes.toBytes(graphReader.getRootTableReader().getTableName()));
            scanStrings.add(convertScanToString(scan));
        }
        conf.setStrings(GraphInputFormat.SCANS, scanStrings.toArray(new String[scanStrings.size()]));

        if (addDependencyJars) {
            addDependencyJars(job);
        }
        initCredentials(job);
    }

    private static List<Scan> createScans(From from, Where where, PlasmaType type, Filter columnFilter,
            Configuration conf) throws IOException {

        List<Scan> result = new ArrayList<Scan>();
        if (where == null) {
            conf.setBoolean(GraphInputFormat.RECOGNIZER, false);
            Scan scan = createDefaultScan(from, type, columnFilter);
            result.add(scan);
            return result;
        }

        ScanRecognizerSyntaxTreeAssembler recognizerAssembler = new ScanRecognizerSyntaxTreeAssembler(where, type);
        Expr scanRecognizerRootExpr = recognizerAssembler.getResult();
        if (LOG.isDebugEnabled()) {
            ExprPrinter printer = new ExprPrinter();
            scanRecognizerRootExpr.accept(printer);
            LOG.debug("Scan Recognizer: " + printer.toString());
        }
        ScanCollector scanCollector = new ScanCollector(type);
        scanRecognizerRootExpr.accept(scanCollector);
        List<PartialRowKey> partialScans = scanCollector.getPartialRowKeyScans();
        List<FuzzyRowKey> fuzzyScans = scanCollector.getFuzzyRowKeyScans();
        List<CompleteRowKey> completeKeys = scanCollector.getCompleteRowKeys();
        if (!scanCollector.isQueryRequiresGraphRecognizer()) {
            conf.setBoolean(GraphInputFormat.RECOGNIZER, false);
            scanRecognizerRootExpr = null;
        } else {
            conf.setBoolean(GraphInputFormat.RECOGNIZER, true);
        }

        if (completeKeys.size() > 0)
            throw new GraphServiceException("expected no complete key values");
        // FIXME: table split by region entirely based on partial key start stop
        // bytes
        for (FuzzyRowKey fuzzyKey : fuzzyScans) {
            Scan scan = createScan(fuzzyKey, columnFilter);
            result.add(scan);
        }
        for (PartialRowKey partialKey : partialScans) {
            Scan scan = createScan(partialKey, columnFilter);
            result.add(scan);
        }

        if (result.size() == 0) {
            Scan scan = createDefaultScan(from, type, columnFilter);
            result.add(scan);
        }

        return result;
    }

    private static Scan createDefaultScan(From from, PlasmaType type, Filter columnFilter) {
        Scan scan;

        PartialRowKeyScanAssembler scanAssembler = new PartialRowKeyScanAssembler(type);
        scanAssembler.assemble();
        byte[] startKey = scanAssembler.getStartKey();
        if (startKey != null && startKey.length > 0) {
            LOG.warn("using default graph partial " + "key scan - could result in very large results set");
            scan = createScan(scanAssembler, columnFilter);
        } else {
            Float sample = from.getRandomSample();
            if (sample == null) {
                FilterList rootFilter = new FilterList(FilterList.Operator.MUST_PASS_ALL);
                scan = new Scan();
                rootFilter.addFilter(columnFilter);
                scan.setFilter(rootFilter);
                LOG.warn("query resulted in no filters or scans - using full table scan - "
                        + "could result in very large results set");
            } else {
                FilterList rootFilter = new FilterList(FilterList.Operator.MUST_PASS_ALL);
                RandomRowFilter rowFilter = new RandomRowFilter(sample);
                rootFilter.addFilter(rowFilter);
                rootFilter.addFilter(columnFilter);
                scan = new Scan();
                scan.setFilter(rootFilter);
                LOG.warn("using random-sample scan (" + sample + ") - " + "could result in very large results set");
            }
        }
        return scan;
    }

    /**
     * Use this before submitting a graph map job. It will appropriately set up
     * the job.
     * 
     * @param query
     *          The query defining the {@link GraphMapper} input graphs.
     * @param mapper
     *          The mapper class to use.
     * @param outputKeyClass
     *          The class of the output key.
     * @param outputValueClass
     *          The class of the output value.
     * @param job
     *          The current job to adjust. Make sure the passed job is carrying
     *          all necessary HBase configuration.
     * @param addDependencyJars
     *          upload HBase jars and jars for any of the configured job classes
     *          via the distributed cache (tmpjars).
     * @throws IOException
     *           When setting up the details fails.
     */
    public static void setupGraphMapperJob(Query query, Class<? extends GraphMapper> mapper,
            Class<? extends WritableComparable> outputKeyClass, Class<? extends Writable> outputValueClass, Job job,
            boolean addDependencyJars) throws IOException {
        setupGraphMapperJob(query, mapper, outputKeyClass, outputValueClass, job, addDependencyJars,
                GraphInputFormat.class);
    }

    public static void initCredentials(Job job) throws IOException {
        UserProvider userProvider = UserProvider.instantiate(job.getConfiguration());
        if (userProvider.isHadoopSecurityEnabled()) {
            // propagate delegation related props from launcher job to MR job
            if (System.getenv("HADOOP_TOKEN_FILE_LOCATION") != null) {
                job.getConfiguration().set("mapreduce.job.credentials.binary",
                        System.getenv("HADOOP_TOKEN_FILE_LOCATION"));
            }
        }

        if (userProvider.isHBaseSecurityEnabled()) {
            try {
                // init credentials for remote cluster
                String quorumAddress = job.getConfiguration().get(TableOutputFormat.QUORUM_ADDRESS);
                User user = userProvider.getCurrent();
                if (quorumAddress != null) {
                    Configuration peerConf = HBaseConfiguration.createClusterConf(job.getConfiguration(),
                            quorumAddress, TableOutputFormat.OUTPUT_CONF_PREFIX);
                    Connection peerConn = ConnectionFactory.createConnection(peerConf);
                    try {
                        TokenUtil.addTokenForJob(peerConn, user, job);
                    } finally {
                        peerConn.close();
                    }
                }

                Connection conn = ConnectionFactory.createConnection(job.getConfiguration());
                try {
                    TokenUtil.addTokenForJob(conn, user, job);
                } finally {
                    conn.close();
                }
            } catch (InterruptedException ie) {
                LOG.info("Interrupted obtaining user authentication token");
                Thread.currentThread().interrupt();
            }
        }
    }

    /**
     * Writes the given scan into a Base64 encoded string.
     *
     * @param scan
     *          The scan to write out.
     * @return The scan saved in a Base64 encoded string.
     * @throws IOException
     *           When writing the scan fails.
     */
    static String convertScanToString(Scan scan) throws IOException {
        ClientProtos.Scan proto = ProtobufUtil.toScan(scan);
        return Base64.encodeBytes(proto.toByteArray());
    }

    /**
     * Converts the given Base64 string back into a Scan instance.
     *
     * @param base64
     *          The scan details.
     * @return The newly created Scan instance.
     * @throws IOException
     *           When reading the scan instance fails.
     */
    static Scan convertStringToScan(String base64) throws IOException {
        byte[] decoded = Base64.decode(base64);
        ClientProtos.Scan scan;
        try {
            scan = ClientProtos.Scan.parseFrom(decoded);
        } catch (InvalidProtocolBufferException ipbe) {
            throw new IOException(ipbe);
        }

        return ProtobufUtil.toScan(scan);
    }

    /**
     * Use this before submitting a graph reduce job. It will appropriately set up
     * the JobConf.
     * 
     * @param tableConfig
     *          The output table.
     * @param reducer
     *          The reducer class to use.
     * @param job
     *          The current job to adjust.
     * @throws IOException
     *           When determining the region count fails.
     */
    public static void setupGraphReducerJob(Query query, Class<? extends GraphReducer> reducer, Job job)
            throws IOException {
        setupGraphReducerJob(query, reducer, job, null);
    }

    /**
     * Use this before submitting a graph reduce job. It will appropriately set up
     * the JobConf.
     * 
     * @param tableConfig
     *          The output table.
     * @param reducer
     *          The reducer class to use.
     * @param job
     *          The current job to adjust.
     * @param partitioner
     *          Partitioner to use. Pass <code>null</code> to use default
     *          partitioner.
     * @throws IOException
     *           When determining the region count fails.
     */
    public static void setupGraphReducerJob(Query query, Class<? extends GraphReducer> reducer, Job job,
            Class partitioner) throws IOException {
        setupGraphReducerJob(query, reducer, job, partitioner, null, null, null);
    }

    /**
     * Use this before submitting a graph reduce job. It will appropriately set up
     * the JobConf.
     * 
     * @param query
     *          The output query.
     * @param reducer
     *          The reducer class to use.
     * @param job
     *          The current job to adjust. Make sure the passed job is carrying
     *          all necessary HBase configuration.
     * @param partitioner
     *          Partitioner to use. Pass <code>null</code> to use default
     *          partitioner.
     * @param quorumAddress
     *          Distant cluster to write to; default is null for output to the
     *          cluster that is designated in <code>hbase-site.xml</code>. Set
     *          this String to the zookeeper ensemble of an alternate remote
     *          cluster when you would have the reduce write a cluster that is
     *          other than the default; e.g. copying tables between clusters, the
     *          source would be designated by <code>hbase-site.xml</code> and this
     *          param would have the ensemble address of the remote cluster. The
     *          format to pass is particular. Pass
     *          <code> &lt;hbase.zookeeper.quorum>:&lt;hbase.zookeeper.client.port>:&lt;zookeeper.znode.parent>
     * </code> such as <code>server,server2,server3:2181:/hbase</code>.
     * @param serverClass
     *          redefined hbase.regionserver.class
     * @param serverImpl
     *          redefined hbase.regionserver.impl
     * @throws IOException
     *           When determining the region count fails.
     */
    public static void setupGraphReducerJob(Query query, Class<? extends GraphReducer> reducer, Job job,
            Class partitioner, String quorumAddress, String serverClass, String serverImpl) throws IOException {
        setupGraphReducerJob(query, reducer, job, partitioner, quorumAddress, serverClass, serverImpl, true);
    }

    /**
     * Use this before submitting a TableReduce job. It will appropriately set up
     * the JobConf.
     * 
     * @param query
     *          The output query.
     * @param reducer
     *          The reducer class to use.
     * @param job
     *          The current job to adjust. Make sure the passed job is carrying
     *          all necessary HBase configuration.
     * @param partitioner
     *          Partitioner to use. Pass <code>null</code> to use default
     *          partitioner.
     * @param quorumAddress
     *          Distant cluster to write to; default is null for output to the
     *          cluster that is designated in <code>hbase-site.xml</code>. Set
     *          this String to the zookeeper ensemble of an alternate remote
     *          cluster when you would have the reduce write a cluster that is
     *          other than the default; e.g. copying tables between clusters, the
     *          source would be designated by <code>hbase-site.xml</code> and this
     *          param would have the ensemble address of the remote cluster. The
     *          format to pass is particular. Pass
     *          <code> &lt;hbase.zookeeper.quorum>:&lt;hbase.zookeeper.client.port>:&lt;zookeeper.znode.parent>
     * </code> such as <code>server,server2,server3:2181:/hbase</code>.
     * @param serverClass
     *          redefined hbase.regionserver.class
     * @param serverImpl
     *          redefined hbase.regionserver.impl
     * @param addDependencyJars
     *          upload HBase jars and jars for any of the configured job classes
     *          via the distributed cache (tmpjars).
     * @throws IOException
     *           When determining the region count fails.
     */
    public static void setupGraphReducerJob(Query query, Class<? extends GraphReducer> reducer, Job job,
            Class partitioner, String quorumAddress, String serverClass, String serverImpl,
            boolean addDependencyJars) throws IOException {

        Configuration conf = job.getConfiguration();
        HBaseConfiguration.merge(conf, HBaseConfiguration.create(conf));

        PlasmaType type = getRootType(query);

        Where where = query.getModel().findWhereClause();
        SelectionCollector selectionCollector = null;
        if (where != null)
            selectionCollector = new SelectionCollector(query.getModel().getSelectClause(), where, type);
        else
            selectionCollector = new SelectionCollector(query.getModel().getSelectClause(), type);
        selectionCollector.setOnlyDeclaredProperties(false);
        // FIXME: generalize collectRowKeyProperties
        for (Type t : selectionCollector.getTypes())
            collectRowKeyProperties(selectionCollector, (PlasmaType) t);

        // DistributedGraphReader graphReader = new DistributedGraphReader(type,
        // selectionCollector.getTypes(), marshallingContext);

        // job.setOutputFormatClass(GraphOutputFormat.class);
        if (reducer != null)
            job.setReducerClass(reducer);

        /*
         * conf.set(TableOutputFormat.OUTPUT_TABLE,
         * graphReader.getRootTableReader().getTableName());
         * 
         * // If passed a quorum/ensemble address, pass it on to TableOutputFormat.
         * if (quorumAddress != null) { // Calling this will validate the format
         * ZKUtil.transformClusterKey(quorumAddress);
         * conf.set(TableOutputFormat.QUORUM_ADDRESS, quorumAddress); } if
         * (serverClass != null && serverImpl != null) {
         * conf.set(TableOutputFormat.REGION_SERVER_CLASS, serverClass);
         * conf.set(TableOutputFormat.REGION_SERVER_IMPL, serverImpl); }
         * job.setOutputKeyClass(ImmutableBytesWritable.class);
         * job.setOutputValueClass(Writable.class); if (partitioner ==
         * HRegionPartitioner.class) {
         * job.setPartitionerClass(HRegionPartitioner.class); HTable outputTable =
         * new HTable(conf, graphReader.getRootTableReader().getTableName()); int
         * regions = outputTable.getRegionsInfo().size(); if
         * (job.getNumReduceTasks() > regions) {
         * job.setNumReduceTasks(outputTable.getRegionsInfo().size()); } } else if
         * (partitioner != null) { job.setPartitionerClass(partitioner); }
         */

        if (addDependencyJars) {
            addDependencyJars(job);
        }

        initCredentials(job);
    }

    /**
     * Ensures that the given number of reduce tasks for the given job
     * configuration does not exceed the number of regions for the given table.
     * 
     * @param table
     *          The table to get the region count for.
     * @param job
     *          The current job to adjust.
     * @throws IOException
     *           When retrieving the table details fails.
     */
    public static void limitNumReduceTasks(String table, Job job) throws IOException {
        HTable outputTable = new HTable(job.getConfiguration(), table);
        int regions = outputTable.getRegionLocations().size();
        if (job.getNumReduceTasks() > regions)
            job.setNumReduceTasks(regions);
    }

    /**
     * Sets the number of reduce tasks for the given job configuration to the
     * number of regions the given table has.
     * 
     * @param table
     *          The table to get the region count for.
     * @param job
     *          The current job to adjust.
     * @throws IOException
     *           When retrieving the table details fails.
     */
    public static void setNumReduceTasks(String table, Job job) throws IOException {
        HTable outputTable = new HTable(job.getConfiguration(), table);
        int regions = outputTable.getRegionLocations().size();
        job.setNumReduceTasks(regions);
    }

    /**
     * Sets the number of rows to return and cache with each scanner iteration.
     * Higher caching values will enable faster mapreduce jobs at the expense of
     * requiring more heap to contain the cached rows.
     * 
     * @param job
     *          The current job to adjust.
     * @param batchSize
     *          The number of rows to return in batch with each scanner iteration.
     */
    public static void setScannerCaching(Job job, int batchSize) {
        job.getConfiguration().setInt("hbase.client.scanner.caching", batchSize);
    }

    /**
     * Add the HBase dependency jars as well as jars for any of the configured job
     * classes to the job configuration, so that JobClient will ship them to the
     * cluster and add them to the DistributedCache.
     */
    public static void addDependencyJars(Job job) throws IOException {
        try {
            addDependencyJars(job.getConfiguration(), org.apache.zookeeper.ZooKeeper.class,
                    com.google.protobuf.Message.class, com.google.common.collect.ImmutableSet.class,
                    org.apache.hadoop.hbase.util.Bytes.class, // one class from
                    // hbase.jar
                    job.getMapOutputKeyClass(), job.getMapOutputValueClass(), job.getInputFormatClass(),
                    job.getOutputKeyClass(), job.getOutputValueClass(), job.getOutputFormatClass(),
                    job.getPartitionerClass(), job.getCombinerClass());
        } catch (ClassNotFoundException e) {
            throw new IOException(e);
        }
    }

    /**
     * Add the jars containing the given classes to the job's configuration such
     * that JobClient will ship them to the cluster and add them to the
     * DistributedCache.
     */
    public static void addDependencyJars(Configuration conf, Class<?>... classes) throws IOException {

        FileSystem localFs = FileSystem.getLocal(conf);
        Set<String> jars = new HashSet<String>();
        // Add jars that are already in the tmpjars variable
        jars.addAll(conf.getStringCollection("tmpjars"));

        // add jars as we find them to a map of contents jar name so that we can
        // avoid
        // creating new jars for classes that have already been packaged.
        Map<String, String> packagedClasses = new HashMap<String, String>();

        // Add jars containing the specified classes
        for (Class<?> clazz : classes) {
            if (clazz == null)
                continue;

            Path path = findOrCreateJar(clazz, localFs, packagedClasses);
            if (path == null) {
                LOG.warn("Could not find jar for class " + clazz + " in order to ship it to the cluster.");
                continue;
            }
            if (!localFs.exists(path)) {
                LOG.warn("Could not validate jar file " + path + " for class " + clazz);
                continue;
            }
            jars.add(path.toString());
        }
        if (jars.isEmpty())
            return;

        conf.set("tmpjars", StringUtils.arrayToString(jars.toArray(new String[0])));
    }

    /**
     * If org.apache.hadoop.util.JarFinder is available (0.23+ hadoop), finds the
     * Jar for a class or creates it if it doesn't exist. If the class is in a
     * directory in the classpath, it creates a Jar on the fly with the contents
     * of the directory and returns the path to that Jar. If a Jar is created, it
     * is created in the system temporary directory. Otherwise, returns an
     * existing jar that contains a class of the same name. Maintains a mapping
     * from jar contents to the tmp jar created.
     * 
     * @param my_class
     *          the class to find.
     * @param fs
     *          the FileSystem with which to qualify the returned path.
     * @param packagedClasses
     *          a map of class name to path.
     * @return a jar file that contains the class.
     * @throws IOException
     */
    private static Path findOrCreateJar(Class<?> my_class, FileSystem fs, Map<String, String> packagedClasses)
            throws IOException {
        // attempt to locate an existing jar for the class.
        String jar = findContainingJar(my_class, packagedClasses);
        if (null == jar || jar.isEmpty()) {
            jar = getJar(my_class);
            updateMap(jar, packagedClasses);
        }

        if (null == jar || jar.isEmpty()) {
            throw new IOException("Cannot locate resource for class " + my_class.getName());
        }

        LOG.debug(String.format("For class %s, using jar %s", my_class.getName(), jar));
        return new Path(jar).makeQualified(fs);
    }

    /**
     * Add entries to <code>packagedClasses</code> corresponding to class files
     * contained in <code>jar</code>.
     * 
     * @param jar
     *          The jar who's content to list.
     * @param packagedClasses
     *          map[class -> jar]
     */
    private static void updateMap(String jar, Map<String, String> packagedClasses) throws IOException {
        ZipFile zip = null;
        try {
            zip = new ZipFile(jar);
            for (Enumeration<? extends ZipEntry> iter = zip.entries(); iter.hasMoreElements();) {
                ZipEntry entry = iter.nextElement();
                if (entry.getName().endsWith("class")) {
                    packagedClasses.put(entry.getName(), jar);
                }
            }
        } finally {
            if (null != zip)
                zip.close();
        }
    }

    /**
     * Find a jar that contains a class of the same name, if any. It will return a
     * jar file, even if that is not the first thing on the class path that has a
     * class with the same name. Looks first on the classpath and then in the
     * <code>packagedClasses</code> map.
     * 
     * @param my_class
     *          the class to find.
     * @return a jar file that contains the class, or null.
     * @throws IOException
     */
    private static String findContainingJar(Class<?> my_class, Map<String, String> packagedClasses)
            throws IOException {
        ClassLoader loader = my_class.getClassLoader();
        String class_file = my_class.getName().replaceAll("\\.", "/") + ".class";

        // first search the classpath
        for (Enumeration<URL> itr = loader.getResources(class_file); itr.hasMoreElements();) {
            URL url = itr.nextElement();
            if ("jar".equals(url.getProtocol())) {
                String toReturn = url.getPath();
                if (toReturn.startsWith("file:")) {
                    toReturn = toReturn.substring("file:".length());
                }
                // URLDecoder is a misnamed class, since it actually decodes
                // x-www-form-urlencoded MIME type rather than actual
                // URL encoding (which the file path has). Therefore it would
                // decode +s to ' 's which is incorrect (spaces are actually
                // either unencoded or encoded as "%20"). Replace +s first, so
                // that they are kept sacred during the decoding process.
                toReturn = toReturn.replaceAll("\\+", "%2B");
                toReturn = URLDecoder.decode(toReturn, "UTF-8");
                return toReturn.replaceAll("!.*$", "");
            }
        }

        // now look in any jars we've packaged using JarFinder. Returns null
        // when
        // no jar is found.
        return packagedClasses.get(class_file);
    }

    /**
     * Invoke 'getJar' on a JarFinder implementation. Useful for some job
     * configuration contexts (HBASE-8140) and also for testing on MRv2. First
     * check if we have HADOOP-9426. Lacking that, fall back to the backport.
     * 
     * @param my_class
     *          the class to find.
     * @return a jar file that contains the class, or null.
     */
    private static String getJar(Class<?> my_class) {
        String ret = null;
        String hadoopJarFinder = "org.apache.hadoop.util.JarFinder";
        Class<?> jarFinder = null;
        try {
            LOG.debug("Looking for " + hadoopJarFinder + ".");
            jarFinder = Class.forName(hadoopJarFinder);
            LOG.debug(hadoopJarFinder + " found.");
            Method getJar = jarFinder.getMethod("getJar", Class.class);
            ret = (String) getJar.invoke(null, my_class);
        } catch (ClassNotFoundException e) {
            LOG.debug("Using backported JarFinder.");
            ret = JarFinder.getJar(my_class);
        } catch (InvocationTargetException e) {
            // function was properly called, but threw it's own exception.
            // Unwrap it
            // and pass it on.
            throw new RuntimeException(e.getCause());
        } catch (Exception e) {
            // toss all other exceptions, related to reflection failure
            throw new RuntimeException("getJar invocation failed.", e);
        }

        return ret;
    }

    // FIXME: generalize
    private static Scan createScan(PartialRowKey partialRowKey, Filter columnFilter) {
        FilterList rootFilter = new FilterList(FilterList.Operator.MUST_PASS_ALL);
        rootFilter.addFilter(columnFilter);
        Scan scan = new Scan();
        scan.setFilter(rootFilter);
        scan.setStartRow(partialRowKey.getStartKey()); // inclusive
        scan.setStopRow(partialRowKey.getStopKey()); // exclusive
        LOG.info("using partial row key scan: (" + "start: '" + Bytes.toString(scan.getStartRow()) + "' stop: '"
                + Bytes.toString(scan.getStopRow()) + "')");
        return scan;
    }

    // FIXME: generalize
    private static Scan createScan(FuzzyRowKey fuzzyScan, Filter columnFilter) throws IOException {
        FilterList rootFilter = new FilterList(FilterList.Operator.MUST_PASS_ALL);
        rootFilter.addFilter(columnFilter);
        Scan scan = new Scan();
        scan.setFilter(rootFilter);
        Filter fuzzyFilter = fuzzyScan.getFilter();
        rootFilter.addFilter(fuzzyFilter);
        LOG.info("using fuzzy scan: " + FilterUtil.printFilterTree(fuzzyFilter));

        return scan;
    }

    private static void collectRowKeyProperties(SelectionCollector collector, PlasmaType type) {
        Config config = StoreMapping.getInstance();
        DataGraphMapping graph = config.findDataGraph(type.getQualifiedName());
        if (graph != null) {
            DataRowKeyFieldMapping[] fields = new DataRowKeyFieldMapping[graph.getUserDefinedRowKeyFields().size()];
            graph.getUserDefinedRowKeyFields().toArray(fields);
            for (DataRowKeyFieldMapping field : fields) {
                List<Type> types = collector.addProperty(graph.getRootType(), field.getPropertyPath());
                for (Type nextType : types)
                    collectRowKeyProperties(collector, (PlasmaType) nextType);
            }
        }
    }

    private static Query unmarshal(File queryFile) {
        try {
            PlasmaQueryDataBinding binding = new PlasmaQueryDataBinding(new DefaultValidationEventHandler());
            FileInputStream fis = new FileInputStream(queryFile);
            return (Query) binding.unmarshal(fis);
        } catch (JAXBException e1) {
            throw new GraphServiceException(e1);
        } catch (SAXException e1) {
            throw new GraphServiceException(e1);
        } catch (FileNotFoundException e) {
            throw new GraphServiceException(e);
        }
    }

    private static Query unmarshal(String xmlQuery) {
        try {
            PlasmaQueryDataBinding binding = new PlasmaQueryDataBinding(new DefaultValidationEventHandler());
            return (Query) binding.unmarshal(xmlQuery);
        } catch (JAXBException e1) {
            throw new GraphServiceException(e1);
        } catch (SAXException e1) {
            throw new GraphServiceException(e1);
        }
    }

    private static String marshal(Query query) {
        try {
            PlasmaQueryDataBinding binding = new PlasmaQueryDataBinding(new DefaultValidationEventHandler());
            return binding.marshal(query);
        } catch (JAXBException e1) {
            throw new GraphServiceException(e1);
        } catch (SAXException e1) {
            throw new GraphServiceException(e1);
        }
    }

}