share

share.js

var config = require('./config');
var workerNum = config['worker_concurrency']

var instanceCount = 1, instanceIndex = 0;

try {
  var dna = require('~/dna.json');
  var instances = dna['engineyard']['environment']['instances'];
  var instanceCount = instances.length;
  var thisInstanceId = dna['engineyard']['this'];
  var instanceIndex = 0;
  for ( ; instanceIndex < instanceCount; instanceIndex++) {
    var instance = instances[instanceIndex];
    if (instance.id === thisInstanceId) break;
  }

} catch (e) {
  instanceCount = 1;
  instanceIndex = 0;
} finally {
  function workerNumPerInstance() {
    return workerNum / instanceCount;
  };

  function startEnd(index) {
    // Expecting to split equally between instances
    var instanceSpan = 256 / instanceCount;
    var instanceStart = instanceSpan * instanceIndex;
    var instanceEnd   = instanceStart + instanceSpan - 1;

    var workerCount = workerNumPerInstance();

    var workerSpan = parseInt(instanceSpan / workerCount);

    var startAt = instanceStart + index * workerSpan;
    var endAt = (index === workerCount - 1) ? instanceEnd :
      (startAt - 1 + workerSpan);

    var startAtHexStr = startAt.toString(16).pad(2) + '*';
    var endAtHexStr = endAt.toString(16).pad(2) + '~';

    return {start: startAtHexStr, end: endAtHexStr};
  };

  module.exports.workerNumPerInstance = workerNumPerInstance;
  module.exports.startEnd = startEnd;
}