eagle-core/eagle-query/eagle-entity-base/src/main/java/org/apache/eagle/log/entity/HBaseLogWriter.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 java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.eagle.common.config.EagleConfigFactory;
import org.apache.hadoop.hbase.client.HTableFactory;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.Put;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class HBaseLogWriter implements LogWriter {
    private static Logger LOG = LoggerFactory.getLogger(HBaseLogWriter.class);
    private static byte[] EMPTY_INDEX_QUALIFER_VALUE = "".getBytes();

    private HTableInterface tbl;
    private String table;
    private String columnFamily;

    public HBaseLogWriter(String table, String columnFamily) {
        // TODO assert for non-null of table and columnFamily
        this.table = table;
        this.columnFamily = columnFamily;
    }

    @Override
    public void open() throws IOException {
        try {
            tbl = EagleConfigFactory.load().getHTable(this.table);
            // LOGGER.info("HBase table " + table + " audo reflush is " + (tbl.isAutoFlush() ? "enabled" :
            // "disabled"));
        } catch (Exception ex) {
            LOG.error("Cannot create htable", ex);
            throw new IOException(ex);
        }
    }

    @Override
    public void close() throws IOException {
        if (tbl != null) {
            new HTableFactory().releaseHTableInterface(tbl);
        }
    }

    @Override
    public void flush() throws IOException {
        tbl.flushCommits();
    }

    protected void populateColumnValues(Put p, InternalLog log) {
        Map<String, byte[]> qualifierValues = log.getQualifierValues();
        // iterate all qualifierValues
        for (Map.Entry<String, byte[]> entry : qualifierValues.entrySet()) {
            p.add(columnFamily.getBytes(), entry.getKey().getBytes(), entry.getValue());
        }

        Map<String, String> tags = log.getTags();
        // iterate all tags, each tag will be stored as a column qualifier
        if (tags != null) {
            for (Map.Entry<String, String> entry : tags.entrySet()) {
                // TODO need a consistent handling of null values
                if (entry.getValue() != null) {
                    p.add(columnFamily.getBytes(), entry.getKey().getBytes(), entry.getValue().getBytes());
                }
            }
        }
    }

    /**
     * TODO need think about if multi-PUT is necessary, by checking if autoFlush works
     */
    @Override
    public byte[] write(InternalLog log) throws IOException {
        final byte[] rowkey = RowkeyBuilder.buildRowkey(log);
        final Put p = new Put(rowkey);
        populateColumnValues(p, log);
        tbl.put(p);
        final List<byte[]> indexRowkeys = log.getIndexRowkeys();
        if (indexRowkeys != null) {
            writeIndexes(rowkey, indexRowkeys);
        }
        return rowkey;
    }

    /**
     * TODO need think about if multi-PUT is necessary, by checking if autoFlush works
     */
    public List<byte[]> write(List<InternalLog> logs) throws IOException {
        final List<Put> puts = new ArrayList<Put>(logs.size());
        final List<byte[]> result = new ArrayList<byte[]>(logs.size());
        for (InternalLog log : logs) {
            final byte[] rowkey = RowkeyBuilder.buildRowkey(log);
            final Put p = new Put(rowkey);
            populateColumnValues(p, log);
            puts.add(p);
            final List<byte[]> indexRowkeys = log.getIndexRowkeys();
            if (indexRowkeys != null) {
                writeIndexes(rowkey, indexRowkeys, puts);
            }
            result.add(rowkey);
        }
        tbl.put(puts);
        return result;
    }

    @Override
    public void updateByRowkey(byte[] rowkey, InternalLog log) throws IOException {
        Put p = new Put(rowkey);
        populateColumnValues(p, log);
        tbl.put(p);
        final List<byte[]> indexRowkeys = log.getIndexRowkeys();
        if (indexRowkeys != null) {
            writeIndexes(rowkey, indexRowkeys);
        }
    }

    private void writeIndexes(byte[] rowkey, List<byte[]> indexRowkeys) throws IOException {
        for (byte[] indexRowkey : indexRowkeys) {
            Put p = new Put(indexRowkey);
            p.add(columnFamily.getBytes(), rowkey, EMPTY_INDEX_QUALIFER_VALUE);
            tbl.put(p);
        }
    }

    private void writeIndexes(byte[] rowkey, List<byte[]> indexRowkeys, List<Put> puts) throws IOException {
        for (byte[] indexRowkey : indexRowkeys) {
            Put p = new Put(indexRowkey);
            p.add(columnFamily.getBytes(), rowkey, EMPTY_INDEX_QUALIFER_VALUE);
            puts.add(p);
            // tbl.put(p);
        }
    }

}