com.twitter.maple.hbase.mapred.TableInputFormat.java Source code

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Here is the source code for com.twitter.maple.hbase.mapred.TableInputFormat.java

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/**
 * Copyright 2010 The Apache Software Foundation
 *
 * 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 com.twitter.maple.hbase.mapred;

import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.mapred.TableInputFormatBase;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.JobConfigurable;
import org.apache.hadoop.util.StringUtils;

/**
 * Convert HBase tabular data into a format that is consumable by Map/Reduce.
 */
public class TableInputFormat extends TableInputFormatBase implements JobConfigurable {
    private final Log LOG = LogFactory.getLog(TableInputFormat.class);

    /**
     * space delimited list of columns
     */
    public static final String COLUMN_LIST = "hbase.mapred.tablecolumns";

    /**
     * Use this jobconf param to specify the input table
     */
    public static final String INPUT_TABLE = "hbase.mapred.inputtable";

    public void configure(JobConf job) {
        String tableName = TableInputFormat.getTableName(job);
        String colArg = job.get(COLUMN_LIST);
        String[] colNames = colArg.split(" ");
        byte[][] m_cols = new byte[colNames.length][];
        for (int i = 0; i < m_cols.length; i++) {
            m_cols[i] = Bytes.toBytes(colNames[i]);
        }
        setInputColumns(m_cols);
        try {
            setHTable(new HTable(HBaseConfiguration.create(job), tableName));
        } catch (Exception e) {
            LOG.error(StringUtils.stringifyException(e));
        }
    }

    public void validateInput(JobConf job) throws IOException {
        // expecting exactly one path
        String tableName = TableInputFormat.getTableName(job);
        if (tableName == null) {
            throw new IOException("expecting one table name");
        }

        // connected to table?
        if (getHTable() == null) {
            throw new IOException("could not connect to table '" + tableName + "'");
        }

        // expecting at least one column
        String colArg = job.get(COLUMN_LIST);
        if (colArg == null || colArg.length() == 0) {
            throw new IOException("expecting at least one column");
        }
    }

    public static void setTableName(JobConf job, String tableName) {
        // Make sure that table has not been set before
        String oldTableName = getTableName(job);
        if (oldTableName != null) {
            throw new RuntimeException("table name already set to: '" + oldTableName + "'");
        }
        job.set(INPUT_TABLE, tableName);
    }

    public static String getTableName(JobConf job) {
        return job.get(INPUT_TABLE);
    }
}