hive-sync/index.js

OT engine for hive.js

/**
 * hive.js
 * Copyright (C) 2013-2015 Marcel Klehr <mklehr@gmx.net>
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
"use strict";
var gulf = require('gulf')
  , WaterlineAdapter = require('./lib/waterline-adapter')

module.exports = setup
module.exports.consumes = ['hooks', 'ot', 'queue', 'broadcast']
module.exports.provides = ['sync']

function setup(plugin, imports, register) {
  var hooks = imports.hooks
    , ot = imports.ot
    , queue = imports.queue
    , broadcast = imports.broadcast

  var sync = { getDocument: function*(){throw new Error('Models are not loaded yet')}
              , createDocument: function*(){throw new Error('Models are not loaded yet')}
              , documents: {}
              }

  hooks.on('orm:initialized', function*(models){

    var Document = models.document
      , Snapshot = models.snapshot
      , User = models.user

    sync.getDocument = function*(docId) {
      if(this.documents[docId]) return this.documents[docId]
      var doc = yield Document.findOne({id: docId})
        , ottype = ot.getOTType(doc.type)
      var document = gulf.Document.load(new WaterlineAdapter(docId, models), ottype
      , function(er){
        if(er) throw er
      })
      this.documents[docId] = document
      wireDocument(docId, document)
      return document
    }

    sync.createDocument = function*(type) {
      var ottype = ot.getOTType(type)
      if(!ottype) throw new Error('Specified document type is not available')

      var content = ottype.create()
        , adapter = new WaterlineAdapter(null, models)
      var doc = yield function(cb) {
        gulf.Document.create(adapter, ottype, content, cb)
      }
      wireDocument(adapter.documentId, doc)
      this.documents[adapter.documentId] = doc

      yield Document.update({id: adapter.documentId}, {type: type})

      return yield Document.findOne({id: adapter.documentId})
    }
  })

  function wireDocument(docId, doc) {
    // Use worker queue
    doc.queue = queue.document(docId)

    var b = broadcast.sync(docId)
    // send edits to other workers
    doc.on('edit', function(edit) {
      b.write(edit.pack())
    })
    // listen to, apply and distribute edits of other workers
    b.on('readable', function() {
      var chunk
      while(chunk = broadcast.read()) {
        var edit = gulf.Edit.unpack(chunk.toString(), doc.ottype)
        try {
          doc.applyEdit(edit)
        }catch(e) {
          console.warn('Applying foreign edit failed', edit, e.stack)
        }
        doc.distributeEdit(edit)
      }
    })
  }

  register(null, {sync: sync})
}