kafka-node/lib/partitioner.js

Client for Apache Kafka v0.8+

'use strict';

var util = require('util');
var _ = require('lodash');

var Partitioner = function () {};

var DefaultPartitioner = function () {};
util.inherits(DefaultPartitioner, Partitioner);

DefaultPartitioner.prototype.getPartition = function (partitions) {
  if (partitions && _.isArray(partitions) && partitions.length > 0) {
    return partitions[0];
  } else {
    return 0;
  }
};

var CyclicPartitioner = function () {
  this.c = 0;
};
util.inherits(CyclicPartitioner, Partitioner);

CyclicPartitioner.prototype.getPartition = function (partitions) {
  if (_.isEmpty(partitions)) return 0;
  return partitions[ this.c++ % partitions.length ];
};

var RandomPartitioner = function () {};
util.inherits(RandomPartitioner, Partitioner);

RandomPartitioner.prototype.getPartition = function (partitions) {
  return partitions[Math.floor(Math.random() * partitions.length)];
};

var KeyedPartitioner = function () {};
util.inherits(KeyedPartitioner, Partitioner);

// Taken from oid package (Dan Bornstein)
// Copyright The Obvious Corporation.
KeyedPartitioner.prototype.hashCode = function (string) {
  var hash = 0;
  var length = string.length;

  for (var i = 0; i < length; i++) {
    hash = ((hash * 31) + string.charCodeAt(i)) & 0x7fffffff;
  }

  return (hash === 0) ? 1 : hash;
};

KeyedPartitioner.prototype.getPartition = function (partitions, key) {
  key = key || '';

  var index = this.hashCode(key) % partitions.length;
  return partitions[index];
};

module.exports.DefaultPartitioner = DefaultPartitioner;
module.exports.CyclicPartitioner = CyclicPartitioner;
module.exports.RandomPartitioner = RandomPartitioner;
module.exports.KeyedPartitioner = KeyedPartitioner;