EggContext.java Source code

Introduction

Here is the source code for EggContext.java

Source

/*
This file is part of Eggshell.
Copyright 2013 George Magiros
    
Eggshell is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
    
Eggshell is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
License for more details.
    
You should have received a copy of the GNU General Public License
along with Eggshell.  If not, see <http://www.gnu.org/licenses/>.
*/

import org.mozilla.javascript.*;
import org.mozilla.javascript.annotations.JSConstructor;
import org.mozilla.javascript.annotations.JSFunction;
import org.mozilla.javascript.annotations.JSGetter;
import org.mozilla.javascript.annotations.JSSetter;

import java.io.IOException;

// hadoop classes
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.Counter;
import org.apache.hadoop.mapreduce.TaskInputOutputContext;

/** An instance of this class encapsulates a Hadoop map-reduce
 *  context.  When a Eggshell map-reduce function is called, its
 *  'this' object will be an instance of this class.  The object
 *  includes properties referencing the standard output and standard
 *  error print streams.  In addition the object has methods to
 *  increment Hadoop metric counters.
 */
public class EggContext extends ScriptableObject {
    private static final long serialVersionUID = 7549795420366559595L;

    /* public static fields */

    /** Holds the current map-reduce task context */
    public static TaskInputOutputContext task;

    /* constructors */

    /** Called when first defined as a Javascript class 
     *  @return This class
     */
    public EggContext() {
    }

    /** The name of this Javascript class as a string 
     *  @return  The string name of this class
     */
    public String getClassName() {
        return "EggContext";
    }

    /* public methods */

    /** Tell Hadoop that the task is making progress despite what it
     *  assumes.
     */
    @JSFunction
    public void progress() {
        task.progress();
    }

    /** Increment the Hadoop metric counter of the passed group and name
     *  by the specified amount.  If value not given then counter is
     *  incremented by one.
     *  @param group   The counter group
     *  @param name    The counter name
     *  @param value   The amount to increment
     */
    @JSFunction
    public void incrCounter(String group, String name, Object value) {
        Counter counter = task.getCounter(group, name);
        if (value instanceof Undefined)
            counter.increment(1);
        if (value instanceof Double)
            counter.increment(((Double) value).longValue());
    }

    /** Set the Hadoop metric counter of the passed group and name to
     *  specified value.
     *  @param group   The counter group
     *  @param name    The counter name
     *  @param value   The value
     */
    @JSFunction
    public void setCounter(String group, String name, Double value) {
        Counter counter = task.getCounter(group, name);
        if (!value.isNaN())
            counter.setValue(value.longValue());
    }

    /** Get the current value of the Hadoop metric counter of the
     *  passed group and name
     *  @param group   The counter group
     *  @param name    The counter name
     *  @return        The current value of the counter
     */
    @JSFunction
    public Double counter(String group, String name) {
        Counter counter = task.getCounter(group, name);
        return new Double(counter.getValue());
    }

    /* setter methods */

    /** Set the status message of the task.
     *  @param message   The status message
     */
    @JSSetter
    public void setStatus(String message) {
        task.setStatus(message);
    }

    /* getter methods */

    /** Get the task attempt ID for the task
     *  @return The Hadoop task attempt ID
     */
    @JSGetter
    public String getTaskAttemptID() {
        return task.getTaskAttemptID().toString();
    }

    /** Get the task context that this object encapsulates
     *  @return The Hadoop task context
     */
    @JSGetter
    public TaskInputOutputContext getContext() {
        return task;
    }

    /** Get the Hadoop Configuration object
     *  @return The Hadoop configuration
     */
    @JSGetter
    public Configuration getConfiguration() {
        return task.getConfiguration();
    }

    /** Get the Job ID for the task
     *  @return The Hadoop job id
     */
    @JSGetter
    public String getJobID() {
        return task.getJobID().toString();
    }

    /** Get the user-specified job name for the task
     *  @return The Hadoop job name
     */
    @JSGetter
    public String getJobName() {
        return task.getJobName();
    }

    /** Get the status message for the task.
     *  @return The status message
     */
    @JSGetter
    public String getStatus() {
        return task.getStatus();
    }
}