library/src/main/java/com/datatorrent/lib/db/jdbc/AbstractJdbcNonTransactionableOutputOperator.java

/*
 * Copyright (c) 2014 DataTorrent, Inc. ALL Rights Reserved.
 *
 * Licensed 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 com.datatorrent.lib.db.jdbc;

import java.sql.PreparedStatement;
import java.sql.SQLException;



import com.datatorrent.api.Context;
import com.datatorrent.lib.db.AbstractStoreOutputOperator;

/**
 * This is a base implementation of a JDBC non transactionable output operator. 
 * Subclasses should implement the method which provides the insertion command.
 * <p></p>
 * @displayName Abstract JDBC Non Transactionable Output
 * @category Database
 * @tags output operator
 *
 * @param <T> The kind of tuples that are being processed
 * @since 1.0.4
 */
public abstract class AbstractJdbcNonTransactionableOutputOperator<T, S extends JdbcStore> extends AbstractStoreOutputOperator<T, S>
{
  protected transient PreparedStatement updateCommand;

  @Override
  public void setup(Context.OperatorContext context)
  {
    super.setup(context);
    try {
      updateCommand = store.getConnection().prepareStatement(getUpdateCommand());
    } catch (SQLException e) {
      throw new RuntimeException(e);
    }
  }

  /**
   * Sets the statement parameters and executes the update
   *
   * @param tuple the tuple being processed
   */
  public void processTuple(T tuple)
  {
    try {
      setStatementParameters(updateCommand, tuple);
      updateCommand.execute();
    } catch (SQLException e) {
      throw new RuntimeException(e);
    }
  }

  /**
   * Gets the statement which insert/update the table in the database.
   *
   * @return the sql statement to update a tuple in the database.
   */
  protected abstract String getUpdateCommand();

  /**
   * Sets the parameter of the insert/update statement with values from the tuple.
   *
   * @param statement
   *          update statement which was returned by {@link #getUpdateCommand()}
   * @param tuple
   *          tuple
   * @throws SQLException
   */
  protected abstract void setStatementParameters(PreparedStatement statement, T tuple) throws SQLException;
}