ape.KillNodeCommand.java Source code

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Here is the source code for ape.KillNodeCommand.java

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/**
  * Copyright (c) 2012 Yahoo! 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. See accompanying LICENSE file.
*/

package ape;

import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.cli.Option;
import org.apache.commons.cli.OptionBuilder;
import org.apache.commons.cli.ParseException;

/**
 * This command will kill a node on the host.  This node can be either a DataNode,
 * TaskTracker, NameNode, or JobTracker.
 * 
 * This kill is executed in an identical fashion to running "kill -9 PID" on the 
 * command line.
 * 
 *
 */
public class KillNodeCommand extends ApeCommand {
    private Option option;

    /**
     * The constructor for this command simply creates its Option object (used by
     * the CLI parser)
     */
    public KillNodeCommand() {
        option = OptionBuilder.withArgName("nodetype").hasArgs(1).withValueSeparator()
                .withDescription("Kills a datanode, tasktracker, jobtracker, or namenode.").withLongOpt("kill-node")
                .create("k");
    }

    public String getName() {
        return option.getLongOpt();
    }

    public Option getOption() {
        return option;
    }

    public boolean runImpl(String[] args) throws ParseException, IOException {
        if (Main.VERBOSE) {
            System.out.println("NodeType: " + args[0]);
        }

        String nodeType = args[0];

        if (nodeType.toLowerCase().equals("datanode") || nodeType.toLowerCase().equals("tasktracker")
                || nodeType.toLowerCase().equals("jobtracker") || nodeType.toLowerCase().equals("namenode")) {
            System.out.println("Kill is about to execute the following command:");

            /**
             * The line of code below sends a very ugly bash command to kill the corresponding process.
             * It gets a list of running processes, then greps it for the node type, then 
             * removes the result generated by running grep, then it gets the process ID of that line 
             * 
             */
            String cmd = "echo \"kill -9 \\$(ps -ef | grep -i " + nodeType
                    + " | grep -v grep | grep -v ape | awk -F ' '  '{print \\$2}')\" > /tmp/kill-node.sh && chmod +x /tmp/kill-node.sh && /tmp/./kill-node.sh && rm /tmp/kill-node.sh";

            System.out.println(cmd);

            ProcessBuilder pb = new ProcessBuilder("bash", "-c", cmd);
            pb.redirectErrorStream(true);
            Process sh = pb.start();
            InputStream shIn = sh.getInputStream();
            try {
                if (sh.waitFor() != 0) {
                    System.out.println("Executing Kill Command failed");
                    return false;
                }
            } catch (InterruptedException e) {
                System.out.println(
                        "The kill command was killed before it could kill its target process.  Kind of ironic really...");
                e.printStackTrace();
                throw new RuntimeException();
            }
            int c;
            while ((c = shIn.read()) != -1) {
                System.out.write(c);
            }
            try {
                shIn.close();
            } catch (IOException e) {
                System.out.println("Could not close InputStream from the kill process.");
                e.printStackTrace();
                return false;
            }
        }

        else {
            System.out.println("Invalid node type: " + nodeType);
            System.out.println("Should be one of the following: DataNode, TaskTracker, NameNode, JobTracker.");
            return false;
        }
        return true;
    }
}