eagle-core/eagle-query/eagle-entity-base/src/main/java/org/apache/eagle/log/entity/index/IndexStreamReader.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.index;

import org.apache.eagle.log.base.taggedlog.TaggedLogAPIEntity;
import org.apache.eagle.log.entity.*;
import org.apache.eagle.log.entity.meta.EntityDefinition;
import org.apache.eagle.log.entity.meta.IndexDefinition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

public abstract class IndexStreamReader extends StreamReader {
    protected final IndexDefinition indexDef;
    protected final SearchCondition condition;
    protected final List<byte[]> indexRowkeys;
    protected LogReader<InternalLog> reader;
    protected long lastTimestamp = 0;
    protected long firstTimestamp = 0;

    protected static final Logger LOG = LoggerFactory.getLogger(IndexStreamReader.class);

    public IndexStreamReader(IndexDefinition indexDef, SearchCondition condition, List<byte[]> indexRowkeys) {
        this.indexDef = indexDef;
        this.condition = condition;
        this.indexRowkeys = indexRowkeys;
        this.reader = null;
    }

    @Override
    public long getLastTimestamp() {
        return lastTimestamp;
    }

    @Override
    public long getFirstTimestamp() {
        return this.firstTimestamp;
    }

    @Override
    public void readAsStream() throws Exception {
        if (reader == null) {
            reader = createIndexReader();
        }
        final EntityDefinition entityDef = indexDef.getEntityDefinition();
        try {
            reader.open();
            InternalLog log;
            int count = 0;
            while ((log = reader.read()) != null) {
                TaggedLogAPIEntity entity = HBaseInternalLogHelper.buildEntity(log, entityDef);
                entity.setSerializeAlias(condition.getOutputAlias());
                entity.setSerializeVerbose(condition.isOutputVerbose());

                if (lastTimestamp == 0 || lastTimestamp < entity.getTimestamp()) {
                    lastTimestamp = entity.getTimestamp();
                }
                if (firstTimestamp == 0 || firstTimestamp > entity.getTimestamp()) {
                    firstTimestamp = entity.getTimestamp();
                }
                for (EntityCreationListener l : listeners) {
                    l.entityCreated(entity);
                }
                if (++count == condition.getPageSize()) {
                    break;
                }
            }
        } catch (IOException ioe) {
            LOG.error("Fail reading log", ioe);
            throw ioe;
        } finally {
            reader.close();
        }
    }

    protected abstract LogReader createIndexReader();

}