xcraft-core-eventstore/lib/eventstore.js

Xcraft event store

'use strict';

var moduleName = 'eventstore';
var moduleVersion = '0.0.1';

var async = require('async');
var path = require('path');
var xLog = require('xcraft-core-log')(moduleName, null);
var xCraft = require('xcraft-core-etc')().load('xcraft');
var Datastore = require('nedb');
var db = null;
var config = null;
var nextEventId = null;

function logErrorIfNeeded(err) {
  if (err) {
    xLog.err(JSON.stringify(err));
  }
}

function loadDatabaseIfNeeded(config, callback) {
  if (db !== null) {
    callback();
    return;
  }

  var dbDatafile = path.join(xCraft.xcraftRoot, config.dbfile);
  xLog.verb('loading datafile: ' + dbDatafile);
  db = new Datastore({filename: dbDatafile});
  db.loadDatabase(function (err) {
    logErrorIfNeeded(err);
    xLog.verb('loaded');
    callback();
  });
}

function setLastEventIdIfNeeded(callback) {
  if (nextEventId !== null) {
    callback();
    return;
  }

  db.count({}, function (err, count) {
    logErrorIfNeeded(err);
    nextEventId = count;
    callback(err);
  });
}

function createIndexIfNeeded(callback) {
  db.ensureIndex({fieldName: 'eventId', unique: true}, function (err) {
    logErrorIfNeeded(err);
    callback(err);
  });
}

function EventStore(conf) {
  config = conf;
}

EventStore.prototype.use = function (callback) {
  async.series(
    [
      function (callback) {
        loadDatabaseIfNeeded(config, callback);
      },
      function (callback) {
        createIndexIfNeeded(callback);
      },
      function (callback) {
        setLastEventIdIfNeeded(callback);
      },
    ],
    function (err) {
      logErrorIfNeeded(err);
      callback();
    }
  );
};

EventStore.prototype.insert = function (busToken, type, data, callback) {
  if (type) {
    var document = {
      eventId: nextEventId,
      event: type,
      data: data,
      busToken: busToken,
      version: moduleVersion,
    };
    db.insert(document, callback);
    nextEventId++;
  } else {
    xLog.warn('malformed xcraft-event');
  }
};

EventStore.prototype.findAll = function (callback) {
  db.find({version: moduleVersion}, callback);
};

EventStore.prototype.findAllByToken = function (token, callback) {
  db.find({busToken: token, version: moduleVersion}, callback);
};

EventStore.prototype.findLastByQuery = function (key, value, callback) {
  var query = {};
  query[key] = value;
  query.version = moduleVersion;
  db.find(query).sort({eventId: 1}).exec(callback);
};

module.exports = EventStore;