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.r;
  
  import java.io.IOException;
  
  import org.rosuda.REngine.REngine;
  import org.rosuda.REngine.REngineCallbacks;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.apex.malhar.lib.db.Connectable;
  
  import com.datatorrent.netlet.util.DTThrowable;
  
  /**
   * @since 2.1.0
   */
  public class REngineConnectable implements Connectable
  {
  
    private transient REngine rengine;
    private static Logger log = LoggerFactory.getLogger(REngineConnectable.class);
  
    // REngine Parameters
    String rEngineClassName = "org.rosuda.REngine.JRI.JRIEngine";
  
    // Parameters to R while creating workspace. Default as
    // --vanilla => Combine --no-save, --no-restore, --no-site-file, --no-init-file and --no-environ
    // Read man page of R for details.
    String[] args = {"--vanilla"};
  
    // No callbacks used, can use REngineStdOutput
    // (http://www.rforge.net/org/doc/org/rosuda/REngine/REngineStdOutput.html)
    // which is the only callback implemented so far.
    REngineCallbacks callBacks = null;
  
    // Wiki: A read–eval–print loop (REPL), also known as an interactive toplevel or language shell,
    // setting to false as not using R in interactive mode.
    boolean runREPL = false;
  
    /*
     * (non-Javadoc)
     *
     * @see org.apache.apex.malhar.lib.db.Connectable#connect()
     */
    @Override
    public void connect() throws IOException
    {
      try {
  
        rengine = REngine.getLastEngine();
        if (rengine == null) {
          // new R-engine
          rengine = REngine.engineForClass(rEngineClassName, args, callBacks, runREPL);
          log.info("Creating new Rengine");
        } else {
          log.info("Got last Rengine");
        }
      } catch (Exception exc) {
        log.error("Exception: ", exc);
        DTThrowable.rethrow(exc);
      }
  
    }
  
    /*
     * (non-Javadoc)
     *
     * @see org.apache.apex.malhar.lib.db.Connectable#disconnect()
     */
    @Override
    public void disconnect() throws IOException
    {
      if (rengine != null) {
        rengine.close();
      }
    }
  
    /*
     * (non-Javadoc)
     *
     * @see org.apache.apex.malhar.lib.db.Connectable#isConnected()
     */
    @Override
    public boolean isConnected()
    {
      return rengine == null ? false : true;
    }
  
    /**
     * @return the rengine
     */
    public REngine getRengine()
    {
      return rengine;
    }
  
    /**
     * @return the rEngineClassName
     */
    public String getrEngineClassName()
    {
      return rEngineClassName;
    }
  
    /**
     * @param rEngineClassName
     *          the rEngineClassName to set
     */
    public void setrEngineClassName(String rEngineClassName)
    {
      this.rEngineClassName = rEngineClassName;
    }
  
    /**
     * @return the args
     */
    public String[] getArgs()
    {
      return args;
    }
  
    /**
     * @param args
     *          the args to set
     */
    public void setArgs(String[] args)
    {
      this.args = args;
    }
  
    /**
     * @return the callBacks
     */
    public REngineCallbacks getCallBacks()
    {
      return callBacks;
    }
  
    /**
     * @param callBacks
     *          the callBacks to set
     */
    public void setCallBacks(REngineCallbacks callBacks)
    {
      this.callBacks = callBacks;
    }
  
    /**
     * @return the runREPL
     */
    public boolean isRunREPL()
    {
      return runREPL;
    }
  
    /**
     * @param runREPL
     *          the runREPL to set
     */
    public void setRunREPL(boolean runREPL)
    {
      this.runREPL = runREPL;
    }
  
  }
  