org.apache.accumulo.hadoopImpl.mapreduce.lib.InputConfigurator.java Source code

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/*
 * 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.accumulo.hadoopImpl.mapreduce.lib;

import static com.google.common.base.Preconditions.checkArgument;
import static java.nio.charset.StandardCharsets.UTF_8;
import static java.util.Objects.requireNonNull;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Base64;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.StringTokenizer;

import org.apache.accumulo.core.client.AccumuloClient;
import org.apache.accumulo.core.client.AccumuloException;
import org.apache.accumulo.core.client.AccumuloSecurityException;
import org.apache.accumulo.core.client.BatchScanner;
import org.apache.accumulo.core.client.ClientSideIteratorScanner;
import org.apache.accumulo.core.client.IsolatedScanner;
import org.apache.accumulo.core.client.IteratorSetting;
import org.apache.accumulo.core.client.RowIterator;
import org.apache.accumulo.core.client.Scanner;
import org.apache.accumulo.core.client.TableNotFoundException;
import org.apache.accumulo.core.client.sample.SamplerConfiguration;
import org.apache.accumulo.core.clientImpl.ClientContext;
import org.apache.accumulo.core.clientImpl.Tables;
import org.apache.accumulo.core.clientImpl.TabletLocator;
import org.apache.accumulo.core.conf.ClientProperty;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.PartialKey;
import org.apache.accumulo.core.data.Range;
import org.apache.accumulo.core.data.TableId;
import org.apache.accumulo.core.data.Value;
import org.apache.accumulo.core.dataImpl.KeyExtent;
import org.apache.accumulo.core.iterators.SortedKeyValueIterator;
import org.apache.accumulo.core.master.state.tables.TableState;
import org.apache.accumulo.core.metadata.MetadataTable;
import org.apache.accumulo.core.metadata.schema.MetadataSchema;
import org.apache.accumulo.core.sample.impl.SamplerConfigurationImpl;
import org.apache.accumulo.core.security.Authorizations;
import org.apache.accumulo.core.security.TablePermission;
import org.apache.accumulo.core.util.Pair;
import org.apache.accumulo.core.util.TextUtil;
import org.apache.accumulo.hadoopImpl.mapreduce.InputTableConfig;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.MapWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.util.StringUtils;

import com.google.common.collect.Maps;

/**
 * @since 1.6.0
 */
public class InputConfigurator extends ConfiguratorBase {

    /**
     * Configuration keys for {@link Scanner}.
     *
     * @since 1.6.0
     */
    public static enum ScanOpts {
        TABLE_NAME, AUTHORIZATIONS, RANGES, COLUMNS, ITERATORS, TABLE_CONFIGS, SAMPLER_CONFIG, CLASSLOADER_CONTEXT, EXECUTION_HINTS
    }

    /**
     * Configuration keys for various features.
     *
     * @since 1.6.0
     */
    public static enum Features {
        AUTO_ADJUST_RANGES, SCAN_ISOLATION, USE_LOCAL_ITERATORS, SCAN_OFFLINE, BATCH_SCANNER, BATCH_SCANNER_THREADS
    }

    /**
     * Sets the name of the context classloader to use for scans
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param context
     *          the name of the context classloader
     * @since 1.8.0
     */
    public static void setClassLoaderContext(Class<?> implementingClass, Configuration conf, String context) {
        checkArgument(context != null, "context is null");
        conf.set(enumToConfKey(implementingClass, ScanOpts.CLASSLOADER_CONTEXT), context);
    }

    /**
     * Gets the name of the context classloader to use for scans
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return the classloader context name
     * @since 1.8.0
     */
    public static String getClassLoaderContext(Class<?> implementingClass, Configuration conf) {
        return conf.get(enumToConfKey(implementingClass, ScanOpts.CLASSLOADER_CONTEXT), null);
    }

    /**
     * Sets the name of the input table, over which this job will scan.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param tableName
     *          the table to use when the tablename is null in the write call
     * @since 1.6.0
     */
    public static void setInputTableName(Class<?> implementingClass, Configuration conf, String tableName) {
        checkArgument(tableName != null, "tableName is null");
        conf.set(enumToConfKey(implementingClass, ScanOpts.TABLE_NAME), tableName);
    }

    /**
     * Sets the name of the input table, over which this job will scan.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @since 1.6.0
     */
    public static String getInputTableName(Class<?> implementingClass, Configuration conf) {
        return conf.get(enumToConfKey(implementingClass, ScanOpts.TABLE_NAME));
    }

    /**
     * Sets the {@link Authorizations} used to scan. Must be a subset of the user's authorization.
     * Defaults to the empty set.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param auths
     *          the user's authorizations
     * @since 1.6.0
     */
    public static void setScanAuthorizations(Class<?> implementingClass, Configuration conf, Authorizations auths) {
        if (auths != null && !auths.isEmpty())
            conf.set(enumToConfKey(implementingClass, ScanOpts.AUTHORIZATIONS), auths.serialize());
    }

    /**
     * Gets the authorizations to set for the scans from the configuration.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return the Accumulo scan authorizations
     * @since 1.6.0
     * @see #setScanAuthorizations(Class, Configuration, Authorizations)
     */
    public static Authorizations getScanAuthorizations(Class<?> implementingClass, Configuration conf) {
        String authString = conf.get(enumToConfKey(implementingClass, ScanOpts.AUTHORIZATIONS));
        return authString == null ? Authorizations.EMPTY : new Authorizations(authString.getBytes(UTF_8));
    }

    /**
     * Sets the input ranges to scan on all input tables for this job. If not set, the entire table
     * will be scanned.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param ranges
     *          the ranges that will be mapped over
     * @throws IllegalArgumentException
     *           if the ranges cannot be encoded into base 64
     * @since 1.6.0
     */
    public static void setRanges(Class<?> implementingClass, Configuration conf, Collection<Range> ranges) {
        checkArgument(ranges != null, "ranges is null");

        ArrayList<String> rangeStrings = new ArrayList<>(ranges.size());
        try {
            for (Range r : ranges) {
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                r.write(new DataOutputStream(baos));
                rangeStrings.add(Base64.getEncoder().encodeToString(baos.toByteArray()));
            }
            conf.setStrings(enumToConfKey(implementingClass, ScanOpts.RANGES), rangeStrings.toArray(new String[0]));
        } catch (IOException ex) {
            throw new IllegalArgumentException("Unable to encode ranges to Base64", ex);
        }
    }

    /**
     * Gets the ranges to scan over from a job.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return the ranges
     * @throws IOException
     *           if the ranges have been encoded improperly
     * @since 1.6.0
     * @see #setRanges(Class, Configuration, Collection)
     */
    public static List<Range> getRanges(Class<?> implementingClass, Configuration conf) throws IOException {

        Collection<String> encodedRanges = conf
                .getStringCollection(enumToConfKey(implementingClass, ScanOpts.RANGES));
        List<Range> ranges = new ArrayList<>();
        for (String rangeString : encodedRanges) {
            ByteArrayInputStream bais = new ByteArrayInputStream(Base64.getDecoder().decode(rangeString));
            Range range = new Range();
            range.readFields(new DataInputStream(bais));
            ranges.add(range);
        }
        return ranges;
    }

    /**
     * Gets a list of the iterator settings (for iterators to apply to a scanner) from this
     * configuration.
     *
     * @see #writeIteratorsToConf(Class, Configuration, Collection)
     */
    public static List<IteratorSetting> getIterators(Class<?> implementingClass, Configuration conf) {
        String iterators = conf.get(enumToConfKey(implementingClass, ScanOpts.ITERATORS));

        // If no iterators are present, return an empty list
        if (iterators == null || iterators.isEmpty())
            return new ArrayList<>();

        // Compose the set of iterators encoded in the job configuration
        StringTokenizer tokens = new StringTokenizer(iterators, StringUtils.COMMA_STR);
        List<IteratorSetting> list = new ArrayList<>();
        try {
            while (tokens.hasMoreTokens()) {
                String itstring = tokens.nextToken();
                ByteArrayInputStream bais = new ByteArrayInputStream(Base64.getDecoder().decode(itstring));
                list.add(new IteratorSetting(new DataInputStream(bais)));
                bais.close();
            }
        } catch (IOException e) {
            throw new IllegalArgumentException("couldn't decode iterator settings");
        }
        return list;
    }

    /**
     * Restricts the columns that will be mapped over for the single input table on this job.
     */
    public static void fetchColumns(Class<?> implementingClass, Configuration conf,
            Collection<IteratorSetting.Column> columnFamilyColumnQualifierPairs) {
        checkArgument(columnFamilyColumnQualifierPairs != null, "columnFamilyColumnQualifierPairs is null");
        String[] columnStrings = serializeColumns(columnFamilyColumnQualifierPairs);
        conf.setStrings(enumToConfKey(implementingClass, ScanOpts.COLUMNS), columnStrings);
    }

    public static String[] serializeColumns(Collection<IteratorSetting.Column> columnFamilyColumnQualifierPairs) {
        checkArgument(columnFamilyColumnQualifierPairs != null, "columnFamilyColumnQualifierPairs is null");
        ArrayList<String> columnStrings = new ArrayList<>(columnFamilyColumnQualifierPairs.size());
        for (Pair<Text, Text> column : columnFamilyColumnQualifierPairs) {

            if (column.getFirst() == null)
                throw new IllegalArgumentException("Column family can not be null");

            String col = Base64.getEncoder().encodeToString(TextUtil.getBytes(column.getFirst()));
            if (column.getSecond() != null)
                col += ":" + Base64.getEncoder().encodeToString(TextUtil.getBytes(column.getSecond()));
            columnStrings.add(col);
        }

        return columnStrings.toArray(new String[0]);
    }

    /**
     * Gets the columns to be mapped over from this job.
     *
     * @see #fetchColumns(Class, Configuration, Collection)
     */
    public static Set<IteratorSetting.Column> getFetchedColumns(Class<?> implementingClass, Configuration conf) {
        checkArgument(conf != null, "conf is null");
        String confValue = conf.get(enumToConfKey(implementingClass, ScanOpts.COLUMNS));
        List<String> serialized = new ArrayList<>();
        if (confValue != null) {
            // Split and include any trailing empty strings to allow empty column families
            for (String val : confValue.split(",", -1)) {
                serialized.add(val);
            }
        }
        return deserializeFetchedColumns(serialized);
    }

    public static Set<IteratorSetting.Column> deserializeFetchedColumns(Collection<String> serialized) {
        Set<IteratorSetting.Column> columns = new HashSet<>();

        if (serialized == null) {
            return columns;
        }

        for (String col : serialized) {
            int idx = col.indexOf(":");
            Text cf = new Text(
                    idx < 0 ? Base64.getDecoder().decode(col) : Base64.getDecoder().decode(col.substring(0, idx)));
            Text cq = idx < 0 ? null : new Text(Base64.getDecoder().decode(col.substring(idx + 1)));
            columns.add(new IteratorSetting.Column(cf, cq));
        }
        return columns;
    }

    /**
     * Serialize the iterators to the hadoop configuration under one key.
     */
    public static void writeIteratorsToConf(Class<?> implementingClass, Configuration conf,
            Collection<IteratorSetting> iterators) {
        String confKey = enumToConfKey(implementingClass, ScanOpts.ITERATORS);
        StringBuilder iterBuilder = new StringBuilder();
        int count = 0;
        for (IteratorSetting cfg : iterators) {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            String newIter;
            try {
                cfg.write(new DataOutputStream(baos));
                newIter = Base64.getEncoder().encodeToString(baos.toByteArray());
                baos.close();
            } catch (IOException e) {
                throw new IllegalArgumentException("unable to serialize IteratorSetting");
            }

            if (count == 0) {
                iterBuilder.append(newIter);
            } else {
                // append the next iterator & reset
                iterBuilder.append(StringUtils.COMMA_STR + newIter);
            }
            count++;
        }
        // Store the iterators w/ the job
        conf.set(confKey, iterBuilder.toString());
    }

    /**
     * Controls the automatic adjustment of ranges for this job. This feature merges overlapping
     * ranges, then splits them to align with tablet boundaries. Disabling this feature will cause
     * exactly one Map task to be created for each specified range. The default setting is enabled. *
     *
     * <p>
     * By default, this feature is <b>enabled</b>.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param enableFeature
     *          the feature is enabled if true, disabled otherwise
     * @see #setRanges(Class, Configuration, Collection)
     * @since 1.6.0
     */
    public static void setAutoAdjustRanges(Class<?> implementingClass, Configuration conf, boolean enableFeature) {
        conf.setBoolean(enumToConfKey(implementingClass, Features.AUTO_ADJUST_RANGES), enableFeature);
    }

    /**
     * Determines whether a configuration has auto-adjust ranges enabled.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return false if the feature is disabled, true otherwise
     * @since 1.6.0
     * @see #setAutoAdjustRanges(Class, Configuration, boolean)
     */
    public static Boolean getAutoAdjustRanges(Class<?> implementingClass, Configuration conf) {
        return conf.getBoolean(enumToConfKey(implementingClass, Features.AUTO_ADJUST_RANGES), true);
    }

    /**
     * Controls the use of the {@link IsolatedScanner} in this job.
     *
     * <p>
     * By default, this feature is <b>disabled</b>.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param enableFeature
     *          the feature is enabled if true, disabled otherwise
     * @since 1.6.0
     */
    public static void setScanIsolation(Class<?> implementingClass, Configuration conf, boolean enableFeature) {
        conf.setBoolean(enumToConfKey(implementingClass, Features.SCAN_ISOLATION), enableFeature);
    }

    /**
     * Determines whether a configuration has isolation enabled.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return true if the feature is enabled, false otherwise
     * @since 1.6.0
     * @see #setScanIsolation(Class, Configuration, boolean)
     */
    public static Boolean isIsolated(Class<?> implementingClass, Configuration conf) {
        return conf.getBoolean(enumToConfKey(implementingClass, Features.SCAN_ISOLATION), false);
    }

    /**
     * Controls the use of the {@link ClientSideIteratorScanner} in this job. Enabling this feature
     * will cause the iterator stack to be constructed within the Map task, rather than within the
     * Accumulo TServer. To use this feature, all classes needed for those iterators must be available
     * on the classpath for the task.
     *
     * <p>
     * By default, this feature is <b>disabled</b>.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param enableFeature
     *          the feature is enabled if true, disabled otherwise
     * @since 1.6.0
     */
    public static void setLocalIterators(Class<?> implementingClass, Configuration conf, boolean enableFeature) {
        conf.setBoolean(enumToConfKey(implementingClass, Features.USE_LOCAL_ITERATORS), enableFeature);
    }

    /**
     * Determines whether a configuration uses local iterators.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return true if the feature is enabled, false otherwise
     * @since 1.6.0
     * @see #setLocalIterators(Class, Configuration, boolean)
     */
    public static Boolean usesLocalIterators(Class<?> implementingClass, Configuration conf) {
        return conf.getBoolean(enumToConfKey(implementingClass, Features.USE_LOCAL_ITERATORS), false);
    }

    /**
     * Enable reading offline tables. By default, this feature is disabled and only online tables are
     * scanned. This will make the map reduce job directly read the table's files. If the table is not
     * offline, then the job will fail. If the table comes online during the map reduce job, it is
     * likely that the job will fail.
     *
     * <p>
     * To use this option, the map reduce user will need access to read the Accumulo directory in
     * HDFS.
     *
     * <p>
     * Reading the offline table will create the scan time iterator stack in the map process. So any
     * iterators that are configured for the table will need to be on the mapper's classpath.
     *
     * <p>
     * One way to use this feature is to clone a table, take the clone offline, and use the clone as
     * the input table for a map reduce job. If you plan to map reduce over the data many times, it
     * may be better to the compact the table, clone it, take it offline, and use the clone for all
     * map reduce jobs. The reason to do this is that compaction will reduce each tablet in the table
     * to one file, and it is faster to read from one file.
     *
     * <p>
     * There are two possible advantages to reading a tables file directly out of HDFS. First, you may
     * see better read performance. Second, it will support speculative execution better. When reading
     * an online table speculative execution can put more load on an already slow tablet server.
     *
     * <p>
     * By default, this feature is <b>disabled</b>.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param enableFeature
     *          the feature is enabled if true, disabled otherwise
     * @since 1.6.0
     */
    public static void setOfflineTableScan(Class<?> implementingClass, Configuration conf, boolean enableFeature) {
        conf.setBoolean(enumToConfKey(implementingClass, Features.SCAN_OFFLINE), enableFeature);
    }

    /**
     * Determines whether a configuration has the offline table scan feature enabled.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return true if the feature is enabled, false otherwise
     * @since 1.6.0
     * @see #setOfflineTableScan(Class, Configuration, boolean)
     */
    public static Boolean isOfflineScan(Class<?> implementingClass, Configuration conf) {
        return conf.getBoolean(enumToConfKey(implementingClass, Features.SCAN_OFFLINE), false);
    }

    /**
     * Controls the use of the {@link BatchScanner} in this job. Using this feature will group ranges
     * by their source tablet per InputSplit and use BatchScanner to read them.
     *
     * <p>
     * By default, this feature is <b>disabled</b>.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param enableFeature
     *          the feature is enabled if true, disabled otherwise
     * @since 1.7.0
     */
    public static void setBatchScan(Class<?> implementingClass, Configuration conf, boolean enableFeature) {
        conf.setBoolean(enumToConfKey(implementingClass, Features.BATCH_SCANNER), enableFeature);
    }

    /**
     * Determines whether a configuration has the BatchScanner feature enabled.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return true if the feature is enabled, false otherwise
     * @since 1.7.0
     * @see #setBatchScan(Class, Configuration, boolean)
     */
    public static Boolean isBatchScan(Class<?> implementingClass, Configuration conf) {
        return conf.getBoolean(enumToConfKey(implementingClass, Features.BATCH_SCANNER), false);
    }

    /**
     * Sets configurations for multiple tables at a time.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param configs
     *          an array of {@link InputTableConfig} objects to associate with the job
     * @since 1.6.0
     */
    public static void setInputTableConfigs(Class<?> implementingClass, Configuration conf,
            Map<String, InputTableConfig> configs) {
        MapWritable mapWritable = new MapWritable();
        for (Map.Entry<String, InputTableConfig> tableConfig : configs.entrySet())
            mapWritable.put(new Text(tableConfig.getKey()), tableConfig.getValue());

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try {
            mapWritable.write(new DataOutputStream(baos));
        } catch (IOException e) {
            throw new IllegalStateException("Table configuration could not be serialized.");
        }

        String confKey = enumToConfKey(implementingClass, ScanOpts.TABLE_CONFIGS);
        conf.set(confKey, Base64.getEncoder().encodeToString(baos.toByteArray()));
    }

    /**
     * Returns all {@link InputTableConfig} objects associated with this job.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @return all of the table query configs for the job
     * @since 1.6.0
     */
    public static Map<String, InputTableConfig> getInputTableConfigs(Class<?> implementingClass,
            Configuration conf) {
        return getInputTableConfigs(implementingClass, conf, getInputTableName(implementingClass, conf));
    }

    /**
     * Returns all {@link InputTableConfig} objects associated with this job.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param tableName
     *          the table name for which to retrieve the configuration
     * @return all of the table query configs for the job
     * @since 1.6.0
     */
    private static Map<String, InputTableConfig> getInputTableConfigs(Class<?> implementingClass,
            Configuration conf, String tableName) {
        Map<String, InputTableConfig> configs = new HashMap<>();
        Map.Entry<String, InputTableConfig> defaultConfig = getDefaultInputTableConfig(implementingClass, conf,
                tableName);
        if (defaultConfig != null)
            configs.put(defaultConfig.getKey(), defaultConfig.getValue());
        String configString = conf.get(enumToConfKey(implementingClass, ScanOpts.TABLE_CONFIGS));
        MapWritable mapWritable = new MapWritable();
        if (configString != null) {
            try {
                byte[] bytes = Base64.getDecoder().decode(configString);
                ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
                mapWritable.readFields(new DataInputStream(bais));
                bais.close();
            } catch (IOException e) {
                throw new IllegalStateException("The table query configurations could not be deserialized"
                        + " from the given configuration");
            }
        }
        for (Map.Entry<Writable, Writable> entry : mapWritable.entrySet())
            configs.put(entry.getKey().toString(), (InputTableConfig) entry.getValue());

        return configs;
    }

    /**
     * Returns the {@link InputTableConfig} for the given table
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param tableName
     *          the table name for which to fetch the table query config
     * @return the table query config for the given table name (if it exists) and null if it does not
     * @since 1.6.0
     */
    public static InputTableConfig getInputTableConfig(Class<?> implementingClass, Configuration conf,
            String tableName) {
        Map<String, InputTableConfig> queryConfigs = getInputTableConfigs(implementingClass, conf, tableName);
        return queryConfigs.get(tableName);
    }

    /**
     * Initializes an Accumulo {@link TabletLocator} based on the configuration.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param tableId
     *          The table id for which to initialize the {@link TabletLocator}
     * @return an Accumulo tablet locator
     * @since 1.6.0
     */
    public static TabletLocator getTabletLocator(Class<?> implementingClass, Configuration conf, TableId tableId) {
        try (AccumuloClient client = createClient(implementingClass, conf)) {
            return TabletLocator.getLocator((ClientContext) client, tableId);
        }
    }

    /**
     * Validates that the user has permissions on the requested tables
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop configuration object to configure
     * @param client
     *          the Accumulo client
     * @since 1.7.0
     */
    public static void validatePermissions(Class<?> implementingClass, Configuration conf, AccumuloClient client)
            throws IOException {
        Map<String, InputTableConfig> inputTableConfigs = getInputTableConfigs(implementingClass, conf);
        try {
            if (getInputTableConfigs(implementingClass, conf).size() == 0)
                throw new IOException("No table set.");

            Properties props = getClientProperties(implementingClass, conf);
            String principal = ClientProperty.AUTH_PRINCIPAL.getValue(props);

            for (Map.Entry<String, InputTableConfig> tableConfig : inputTableConfigs.entrySet()) {
                if (!client.securityOperations().hasTablePermission(principal, tableConfig.getKey(),
                        TablePermission.READ))
                    throw new IOException("Unable to access table");
            }
            for (Map.Entry<String, InputTableConfig> tableConfigEntry : inputTableConfigs.entrySet()) {
                InputTableConfig tableConfig = tableConfigEntry.getValue();
                if (!tableConfig.shouldUseLocalIterators()) {
                    if (tableConfig.getIterators() != null) {
                        for (IteratorSetting iter : tableConfig.getIterators()) {
                            if (!client.tableOperations().testClassLoad(tableConfigEntry.getKey(),
                                    iter.getIteratorClass(), SortedKeyValueIterator.class.getName()))
                                throw new AccumuloException("Servers are unable to load " + iter.getIteratorClass()
                                        + " as a " + SortedKeyValueIterator.class.getName());
                        }
                    }
                }
            }
        } catch (AccumuloException | TableNotFoundException | AccumuloSecurityException e) {
            throw new IOException(e);
        }
    }

    /**
     * Returns the {@link InputTableConfig} for the configuration based on the properties set using
     * the single-table input methods.
     *
     * @param implementingClass
     *          the class whose name will be used as a prefix for the property configuration key
     * @param conf
     *          the Hadoop instance for which to retrieve the configuration
     * @param tableName
     *          the table name for which to retrieve the configuration
     * @return the config object built from the single input table properties set on the job
     * @since 1.6.0
     */
    protected static Map.Entry<String, InputTableConfig> getDefaultInputTableConfig(Class<?> implementingClass,
            Configuration conf, String tableName) {
        if (tableName != null) {
            InputTableConfig queryConfig = new InputTableConfig();
            List<IteratorSetting> itrs = getIterators(implementingClass, conf);
            if (itrs != null)
                itrs.forEach(itr -> queryConfig.addIterator(itr));
            Set<IteratorSetting.Column> columns = getFetchedColumns(implementingClass, conf);
            if (columns != null)
                queryConfig.fetchColumns(columns);
            List<Range> ranges = null;
            try {
                ranges = getRanges(implementingClass, conf);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            if (ranges != null)
                queryConfig.setRanges(ranges);

            SamplerConfiguration samplerConfig = getSamplerConfiguration(implementingClass, conf);
            if (samplerConfig != null) {
                queryConfig.setSamplerConfiguration(samplerConfig);
            }

            queryConfig.setAutoAdjustRanges(getAutoAdjustRanges(implementingClass, conf))
                    .setUseIsolatedScanners(isIsolated(implementingClass, conf))
                    .setUseLocalIterators(usesLocalIterators(implementingClass, conf))
                    .setOfflineScan(isOfflineScan(implementingClass, conf))
                    .setExecutionHints(getExecutionHints(implementingClass, conf));
            return Maps.immutableEntry(tableName, queryConfig);
        }
        return null;
    }

    public static Map<String, Map<KeyExtent, List<Range>>> binOffline(TableId tableId, List<Range> ranges,
            ClientContext context) throws AccumuloException, TableNotFoundException {
        Map<String, Map<KeyExtent, List<Range>>> binnedRanges = new HashMap<>();

        if (Tables.getTableState(context, tableId) != TableState.OFFLINE) {
            Tables.clearCache(context);
            if (Tables.getTableState(context, tableId) != TableState.OFFLINE) {
                throw new AccumuloException(
                        "Table is online tableId:" + tableId + " cannot scan table in offline mode ");
            }
        }

        for (Range range : ranges) {
            Text startRow;

            if (range.getStartKey() != null)
                startRow = range.getStartKey().getRow();
            else
                startRow = new Text();

            Range metadataRange = new Range(new KeyExtent(tableId, startRow, null).getMetadataEntry(), true, null,
                    false);
            Scanner scanner = context.createScanner(MetadataTable.NAME, Authorizations.EMPTY);
            MetadataSchema.TabletsSection.TabletColumnFamily.PREV_ROW_COLUMN.fetch(scanner);
            scanner.fetchColumnFamily(MetadataSchema.TabletsSection.LastLocationColumnFamily.NAME);
            scanner.fetchColumnFamily(MetadataSchema.TabletsSection.CurrentLocationColumnFamily.NAME);
            scanner.fetchColumnFamily(MetadataSchema.TabletsSection.FutureLocationColumnFamily.NAME);
            scanner.setRange(metadataRange);

            RowIterator rowIter = new RowIterator(scanner);
            KeyExtent lastExtent = null;
            while (rowIter.hasNext()) {
                Iterator<Map.Entry<Key, Value>> row = rowIter.next();
                String last = "";
                KeyExtent extent = null;
                String location = null;

                while (row.hasNext()) {
                    Map.Entry<Key, Value> entry = row.next();
                    Key key = entry.getKey();

                    if (key.getColumnFamily().equals(MetadataSchema.TabletsSection.LastLocationColumnFamily.NAME)) {
                        last = entry.getValue().toString();
                    }

                    if (key.getColumnFamily().equals(MetadataSchema.TabletsSection.CurrentLocationColumnFamily.NAME)
                            || key.getColumnFamily()
                                    .equals(MetadataSchema.TabletsSection.FutureLocationColumnFamily.NAME)) {
                        location = entry.getValue().toString();
                    }

                    if (MetadataSchema.TabletsSection.TabletColumnFamily.PREV_ROW_COLUMN.hasColumns(key)) {
                        extent = new KeyExtent(key.getRow(), entry.getValue());
                    }

                }

                if (location != null)
                    return null;

                if (!extent.getTableId().equals(tableId)) {
                    throw new AccumuloException("Saw unexpected table Id " + tableId + " " + extent);
                }

                if (lastExtent != null && !extent.isPreviousExtent(lastExtent)) {
                    throw new AccumuloException(" " + lastExtent + " is not previous extent " + extent);
                }

                Map<KeyExtent, List<Range>> tabletRanges = binnedRanges.get(last);
                if (tabletRanges == null) {
                    tabletRanges = new HashMap<>();
                    binnedRanges.put(last, tabletRanges);
                }

                List<Range> rangeList = tabletRanges.get(extent);
                if (rangeList == null) {
                    rangeList = new ArrayList<>();
                    tabletRanges.put(extent, rangeList);
                }

                rangeList.add(range);

                if (extent.getEndRow() == null
                        || range.afterEndKey(new Key(extent.getEndRow()).followingKey(PartialKey.ROW))) {
                    break;
                }

                lastExtent = extent;
            }

        }
        return binnedRanges;
    }

    private static String toBase64(Writable writable) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        DataOutputStream dos = new DataOutputStream(baos);
        try {
            writable.write(dos);
            dos.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        return Base64.getEncoder().encodeToString(baos.toByteArray());
    }

    private static <T extends Writable> T fromBase64(T writable, String enc) {
        ByteArrayInputStream bais = new ByteArrayInputStream(Base64.getDecoder().decode(enc));
        DataInputStream dis = new DataInputStream(bais);
        try {
            writable.readFields(dis);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        return writable;
    }

    public static void setSamplerConfiguration(Class<?> implementingClass, Configuration conf,
            SamplerConfiguration samplerConfig) {
        requireNonNull(samplerConfig);

        String key = enumToConfKey(implementingClass, ScanOpts.SAMPLER_CONFIG);
        String val = toBase64(new SamplerConfigurationImpl(samplerConfig));

        conf.set(key, val);
    }

    public static SamplerConfiguration getSamplerConfiguration(Class<?> implementingClass, Configuration conf) {
        String key = enumToConfKey(implementingClass, ScanOpts.SAMPLER_CONFIG);

        String encodedSC = conf.get(key);
        if (encodedSC == null)
            return null;

        return fromBase64(new SamplerConfigurationImpl(), encodedSC).toSamplerConfiguration();
    }

    public static void setExecutionHints(Class<?> implementingClass, Configuration conf,
            Map<String, String> hints) {
        MapWritable mapWritable = new MapWritable();
        hints.forEach((k, v) -> mapWritable.put(new Text(k), new Text(v)));

        String key = enumToConfKey(implementingClass, ScanOpts.EXECUTION_HINTS);
        String val = toBase64(mapWritable);

        conf.set(key, val);
    }

    public static Map<String, String> getExecutionHints(Class<?> implementingClass, Configuration conf) {
        String key = enumToConfKey(implementingClass, ScanOpts.EXECUTION_HINTS);
        String encodedEH = conf.get(key);
        if (encodedEH == null) {
            return Collections.emptyMap();
        }

        MapWritable mapWritable = new MapWritable();
        fromBase64(mapWritable, encodedEH);

        HashMap<String, String> hints = new HashMap<>();
        mapWritable.forEach((k, v) -> hints.put(k.toString(), v.toString()));
        return hints;
    }
}