Source: eclairjs/Accumulator.js

/*                                                                         
 * Copyright 2015 IBM Corp.
 *
 * 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.
 */

(function () {

    var JavaWrapper = require(EclairJS_Globals.NAMESPACE + '/JavaWrapper');
    var Logger = require(EclairJS_Globals.NAMESPACE + '/Logger');
    var Utils = require(EclairJS_Globals.NAMESPACE + '/Utils');
    var Accumulable = require(EclairJS_Globals.NAMESPACE + '/Accumulable');
    var logger = Logger.getLogger("Accumulator_js");


    /**
     * A simpler value of {@link Accumulable} where the result type being accumulated is the same
     * as the types of elements being merged, i.e. variables that are only "added" to through an
     * associative operation and can therefore be efficiently supported in parallel. They can be used
     * to implement counters (as in MapReduce) or sums. EclairJS supports accumulators of numeric
     * value types.
     *
     * An accumulator is created from an initial value `v` by calling [[SparkContext#accumulator]].
     * Tasks running on the cluster can then add to it using the [[Accumulable#add]].
     * However, they cannot read its value. Only the driver program can read the accumulator's value,
     * using its value method.
     *
     *
     * @example
     *    var accum = sparkContext.accumulator(0);
     *    sparkContext.parallelize([1, 2, 3, 4])
     *                .foreach(function(x, accum) {
 *					accum.add(x);
 *				});
     *    print(accum.value()); // displays 10
     *
     * @classdesc
     * @param {number} initialValue
     * @param {module:eclairjs.AccumulableParam} param
     * @param {string} name human-readable name for use in Spark's web UI
     * @constructor
     * @memberof module:eclairjs
     * @extends module:eclairjs.Accumulable
     */
    var Accumulator = function (initialValue, param, name) {
        logger.debug("constructor");

        Accumulable.apply(this, arguments);

    };

    Accumulator.prototype = Object.create(Accumulable.prototype);

    Accumulator.prototype.constructor = Accumulator;


    module.exports = Accumulator;

})();