eagle-core/eagle-query/eagle-entity-base/src/main/java/org/apache/eagle/log/entity/GenericEntityBatchReader.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.base.taggedlog.TaggedLogAPIEntity;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.List;

public class GenericEntityBatchReader implements EntityCreationListener {
    private static final Logger LOG = LoggerFactory.getLogger(GenericEntityBatchReader.class);

    private List<TaggedLogAPIEntity> entities = new ArrayList<TaggedLogAPIEntity>();
    private StreamReader reader;

    public GenericEntityBatchReader(String serviceName, SearchCondition condition)
        throws InstantiationException, IllegalAccessException {
        reader = new GenericEntityStreamReader(serviceName, condition);
        reader.register(this);
    }

    public GenericEntityBatchReader(StreamReader reader)
        throws InstantiationException, IllegalAccessException {
        this.reader = reader;
        reader.register(this);
    }

    public long getLastTimestamp() {
        return reader.getLastTimestamp();
    }

    public long getFirstTimestamp() {
        return reader.getFirstTimestamp();
    }

    @Override
    public void entityCreated(TaggedLogAPIEntity entity) {
        entities.add(entity);
    }

    @SuppressWarnings("unchecked")
    public <T> List<T> read() throws Exception {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Start reading as batch mode");
        }
        reader.readAsStream();
        return (List<T>)entities;
    }
}