content: /**
   * 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.apex.malhar.contrib.solr;
  
  import java.io.IOException;
  
  import javax.validation.constraints.NotNull;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.apache.apex.malhar.lib.db.AbstractStoreInputOperator;
  import org.apache.solr.client.solrj.SolrServer;
  import org.apache.solr.client.solrj.SolrServerException;
  import org.apache.solr.client.solrj.response.QueryResponse;
  import org.apache.solr.common.SolrDocument;
  import org.apache.solr.common.SolrDocumentList;
  import org.apache.solr.common.params.SolrParams;
  
  import com.datatorrent.api.Context.OperatorContext;
  
  /**
   * This is a base implementation of a Solr input operator, which consumes data from solr search operations.&nbsp;
   * Subclasses should implement the methods getQueryParams, emitTuple for emitting tuples to downstream operators.
   * <p>
   * Compile time checks:<br>
   * Class derived from this has to implement the abstract method getQueryParams() and emitTuple() <br>
   * <br>
   * Run time checks:<br>
   * None<br>
   * <br>
   * Benchmarks:<br>
   * TBD<br>
   * <br>
   *
   * Shipped jars with this operator:<br>
   * <b>org.apache.solr.client.solrj.SolrServer.class</b> Solrj - Solr Java Client <br>
   * <br>
   * </p>
   *
   * @displayName Abstract Solr Input
   * @category Search Engine
   * @tags input operator
   *
   * @since 2.0.0
   */
  
  public abstract class AbstractSolrInputOperator<T, S extends SolrServerConnector> extends AbstractStoreInputOperator<T, S>
  {
    private static final Logger logger = LoggerFactory.getLogger(AbstractSolrInputOperator.class);
    @NotNull
    protected S solrServerConnector;
    private SolrDocument lastEmittedTuple;
    private long lastEmittedTimeStamp;
  
    @Override
    public void beginWindow(long windowId)
    {
    }
  
    @Override
    public void endWindow()
    {
    }
  
    @Override
    public void setup(OperatorContext context)
    {
      try {
        solrServerConnector.connect();
      } catch (IOException ex) {
        throw new RuntimeException("Unable to connect to Solr Server", ex);
      }
    }
  
    @Override
    public void teardown()
    {
      solrServerConnector.getSolrServer().shutdown();
    }
  
    public long getLastEmittedTimeStamp()
    {
      return lastEmittedTimeStamp;
    }
  
    public SolrDocument getLastEmittedTuple()
    {
      return lastEmittedTuple;
    }
  
    public SolrServer getSolrServer()
    {
      return solrServerConnector.getSolrServer();
    }
  
    public SolrServerConnector getSolrServerConnector()
    {
      return solrServerConnector;
    }
  
    public void setSolrServerConnector(S solrServerConnector)
    {
      this.solrServerConnector = solrServerConnector;
    }
  
    @Override
    public void emitTuples()
    {
      SolrParams solrQueryParams = getQueryParams();
      try {
        SolrServer solrServer = solrServerConnector.getSolrServer();
        QueryResponse response = solrServer.query(solrQueryParams);
        SolrDocumentList queriedDocuments = response.getResults();
        for (SolrDocument solrDocument : queriedDocuments) {
          emitTuple(solrDocument);
          lastEmittedTuple = solrDocument;
          lastEmittedTimeStamp = System.currentTimeMillis();
  
          logger.debug("Emiting document: " + solrDocument.getFieldValue("name"));
        }
      } catch (SolrServerException ex) {
        throw new RuntimeException("Unable to fetch documents from Solr server", ex);
      }
    }
  
    /**
     * Initialize SolrServer object
     */
  
    protected abstract void emitTuple(SolrDocument document);
  
    /**
     * Any concrete class has to override this method to return the query string which will be used to retrieve documents
     * from Solr server.
     *
     * @return Query string
     */
    public abstract SolrParams getQueryParams();
  
  }
  