SingleProjectQueryEngine.java

/*
 * Licensed to STRATIO (C) under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional information
 * regarding copyright ownership.  The STRATIO (C) 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 com.stratio.connector.commons.engine;

import com.stratio.connector.commons.connection.Connection;
import com.stratio.connector.commons.connection.ConnectionHandler;
import com.stratio.crossdata.common.connector.IResultHandler;
import com.stratio.crossdata.common.data.ClusterName;
import com.stratio.crossdata.common.exceptions.ConnectorException;
import com.stratio.crossdata.common.exceptions.ExecutionException;
import com.stratio.crossdata.common.exceptions.UnsupportedException;
import com.stratio.crossdata.common.logicalplan.LogicalWorkflow;
import com.stratio.crossdata.common.logicalplan.Project;
import com.stratio.crossdata.common.result.QueryResult;

/**
 * This abstract class is a Template for CommonsQueryEngine. This template only supports a project in the workflow.
 *
 * @param <T> the native client
 */
public abstract class SingleProjectQueryEngine<T> extends CommonsQueryEngine {

    /**
     * Constructor.
     *
     * @param connectionHandler the connector handler.
     */
    public SingleProjectQueryEngine(ConnectionHandler connectionHandler) {
        super(connectionHandler);
    }

    /**
     * This method execute a query with only a project.
     *
     * @param workflow the workflow to be executed.
     * @return the query result.
     * @throws ConnectorException if an error happens.
     */
    @Override
    protected final QueryResult executeWorkFlow(LogicalWorkflow workflow) throws ConnectorException {

        checkIsSupported(workflow);
        ClusterName clusterName = ((Project) workflow.getInitialSteps().get(0)).getClusterName();

        return execute((Project) workflow.getInitialSteps().get(0),
                connectionHandler.getConnection(clusterName.getName()));
    }

    /**
     * Abstract method which must be implemented by the concrete database metadataEngine to execute a async workflow.
     *
     * @param queryId       the queryId.
     * @param workflow      the workflow.
     * @param resultHandler the result handler.
     * @throws ConnectorException if an error happens.
     */
    protected final void asyncExecuteWorkFlow(String queryId, LogicalWorkflow workflow, IResultHandler
            resultHandler) throws ConnectorException {
        checkIsSupported(workflow);
        ClusterName clusterName = ((Project) workflow.getInitialSteps().get(0)).getClusterName();
        asyncExecute(queryId, (Project) workflow.getInitialSteps().get(0),
                connectionHandler.getConnection(clusterName.getName()), resultHandler);
    }


    /**
     * Abstract method which must be implemented by the concrete database metadataEngine to execute a async and paged
     * workflow.
     *
     * @param queryId       the queryId.
     * @param workflow      the workflow.
     * @param resultHandler the result handler.
     * @param pageSize
     * @throws ConnectorException if an error happens.
     */
    protected final void pagedExecuteWorkFlow(String queryId, LogicalWorkflow workflow, IResultHandler resultHandler,
                                              int pageSize) throws ConnectorException {

        checkIsSupported(workflow);
        ClusterName clusterName = ((Project) workflow.getInitialSteps().get(0)).getClusterName();
        pagedExecute(queryId, (Project) workflow.getInitialSteps().get(0),
                connectionHandler.getConnection(clusterName.getName()), resultHandler);
    }


    /**
     * Abstract method which must be implemented by the concrete database metadataEngine to execute a project with only
     * a project.
     *
     * @param project    the project.
     * @param connection the connection to the database.
     * @throws UnsupportedException if an operation is not supported.
     * @throws ExecutionException   if a error happens.
     */
    protected abstract QueryResult execute(Project project, Connection<T> connection) throws ConnectorException;


    /**
     * Abstract method which must be implemented by the concrete database metadataEngine to execute a  async workflow with only
     * a project.
     *
     * @param queryId
     * @param project    the project.
     * @param connection the connection to the database.
     * @throws UnsupportedException if an operation is not supported.
     * @throws ExecutionException   if a error happens.
     */

    protected abstract void asyncExecute(String queryId, Project project, Connection connection, IResultHandler resultHandler) throws ConnectorException;


    /**
     * Abstract method which must be implemented by the concrete database metadataEngine to execute a  paged workflow with only
     * a project.
     *
     * @param queryId
     * @param project    the project.
     * @param connection the connection to the database.
     * @throws UnsupportedException if an operation is not supported.
     * @throws ExecutionException   if a error happens.
     */

    protected abstract void pagedExecute(String queryId, Project project, Connection connection, IResultHandler resultHandler) throws ConnectorException;


    /**
     * Check if the workflow is supported.
     *
     * @param workflow the workflow
     * @throws ExecutionException if the workflow is not supported.
     */
    private void checkIsSupported(LogicalWorkflow workflow) throws ExecutionException {
        if (workflow.getInitialSteps().size() != 1) {
            throw new ExecutionException("The connector can only execute queries with one Project");
        }
    }

}