bagpipes/lib/fittings/parallel.js

Less code, more flow. Let's dance!

'use strict';

var debug = require('debug')('pipes');
var async = require('async');
var _ = require('lodash');
var pipeworks = require('pipeworks');
var helpers = require('../helpers');


// todo: this only currently works with backward references

module.exports = function create(fittingDef, bagpipes) {

  return function parallel(context, cb) {
    debug('create parallel');

    var tasks = {};
    _.each(context.input, function(pipeNameOrDef, key) {
      var pipe = (typeof pipeNameOrDef === 'string')
                  ? bagpipes.getPipe(pipeNameOrDef)
                  : bagpipes.getPipe(null, pipeNameOrDef);
      tasks[key] = createTask(context, pipe, key);
    });

    async.parallel(tasks, function(err, result) {
      debug('parallel done');
      cb(err, result);
    });
  };
};

function createTask(context, pipe, name) {
  return function execTask(cb) {
    pipeworks()
      .fit(function startParallel(context, next) {
        debug('starting parallel pipe: %s', name);
        pipe.siphon(context, next);
      })
      .fit(function finishParallel(context, ignore) {
        debug('finished parallel pipe: %s', name);
        cb(null, context.output);
      })
      .fault(helpers.faultHandler)
      .flow(context);
  }
}