eagle-core/eagle-query/eagle-entity-base/src/main/java/org/apache/eagle/log/entity/HBaseLogReader2.java

/*
 * 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.eagle.log.entity;

import org.apache.eagle.log.entity.meta.EntityDefinition;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.Filter;

import java.io.IOException;
import java.util.Date;
import java.util.List;

public class HBaseLogReader2 extends AbstractHBaseLogReader<InternalLog> {
    protected ResultScanner rs;

    public HBaseLogReader2(EntityDefinition ed, List<String> partitions, Date startTime, Date endTime,
                           Filter filter, String lastScanKey, byte[][] outputQualifiers) {
        super(ed, partitions, startTime, endTime, filter, lastScanKey, outputQualifiers);
    }

    /**
     * This constructor supports partition.
     *
     * @param ed entity definition
     * @param partitions partition values, which is sorted in partition definition order. TODO: in future we
     *            need to support multiple values for one partition field
     * @param startTime start time of the query
     * @param endTime end time of the query
     * @param filter filter for the hbase scan
     * @param lastScanKey the key of last scan
     * @param outputQualifiers the bytes of output qualifier names
     * @param prefix can be populated from outside world specifically for generic metric reader
     */
    public HBaseLogReader2(EntityDefinition ed, List<String> partitions, Date startTime, Date endTime,
                           Filter filter, String lastScanKey, byte[][] outputQualifiers, String prefix) {
        super(ed, partitions, startTime, endTime, filter, lastScanKey, outputQualifiers, prefix);
    }

    @Override
    protected void onOpen(HTableInterface tbl, Scan scan) throws IOException {
        rs = tbl.getScanner(scan);
    }

    /**
     * <h2>Close:</h2> 1. Call super.close(): release current table connection <br>
     * <br>
     * 2. Close Scanner<br>
     * <br>
     *
     * @throws IOException
     */
    @Override
    public void close() throws IOException {
        super.close();
        if (rs != null) {
            rs.close();
        }
    }

    @Override
    public InternalLog read() throws IOException {
        if (rs == null) {
            throw new IllegalArgumentException("ResultScanner must be initialized before reading");
        }
        InternalLog t = null;
        Result r = rs.next();
        if (r != null) {
            t = HBaseInternalLogHelper.parse(ed, r, qualifiers);
        }
        return t;
    }
}