Overleaf/services/real-time/app/js/ConnectedUsersManager.js

/* eslint-disable
    camelcase,
*/
const async = require('async')
const Settings = require('settings-sharelatex')
const logger = require('logger-sharelatex')
const redis = require('redis-sharelatex')
const rclient = redis.createClient(Settings.redis.realtime)
const Keys = Settings.redis.realtime.key_schema

const ONE_HOUR_IN_S = 60 * 60
const ONE_DAY_IN_S = ONE_HOUR_IN_S * 24
const FOUR_DAYS_IN_S = ONE_DAY_IN_S * 4

const USER_TIMEOUT_IN_S = ONE_HOUR_IN_S / 4
const REFRESH_TIMEOUT_IN_S = 10 // only show clients which have responded to a refresh request in the last 10 seconds

module.exports = {
  // Use the same method for when a user connects, and when a user sends a cursor
  // update. This way we don't care if the connected_user key has expired when
  // we receive a cursor update.
  updateUserPosition(project_id, client_id, user, cursorData, callback) {
    logger.log({ project_id, client_id }, 'marking user as joined or connected')

    const multi = rclient.multi()

    multi.sadd(Keys.clientsInProject({ project_id }), client_id)
    multi.expire(Keys.clientsInProject({ project_id }), FOUR_DAYS_IN_S)

    multi.hset(
      Keys.connectedUser({ project_id, client_id }),
      'last_updated_at',
      Date.now()
    )
    multi.hset(
      Keys.connectedUser({ project_id, client_id }),
      'user_id',
      user._id
    )
    multi.hset(
      Keys.connectedUser({ project_id, client_id }),
      'first_name',
      user.first_name || ''
    )
    multi.hset(
      Keys.connectedUser({ project_id, client_id }),
      'last_name',
      user.last_name || ''
    )
    multi.hset(
      Keys.connectedUser({ project_id, client_id }),
      'email',
      user.email || ''
    )

    if (cursorData) {
      multi.hset(
        Keys.connectedUser({ project_id, client_id }),
        'cursorData',
        JSON.stringify(cursorData)
      )
    }
    multi.expire(
      Keys.connectedUser({ project_id, client_id }),
      USER_TIMEOUT_IN_S
    )

    multi.exec(function (err) {
      if (err) {
        logger.err(
          { err, project_id, client_id },
          'problem marking user as connected'
        )
      }
      callback(err)
    })
  },

  refreshClient(project_id, client_id) {
    logger.log({ project_id, client_id }, 'refreshing connected client')
    const multi = rclient.multi()
    multi.hset(
      Keys.connectedUser({ project_id, client_id }),
      'last_updated_at',
      Date.now()
    )
    multi.expire(
      Keys.connectedUser({ project_id, client_id }),
      USER_TIMEOUT_IN_S
    )
    multi.exec(function (err) {
      if (err) {
        logger.err(
          { err, project_id, client_id },
          'problem refreshing connected client'
        )
      }
    })
  },

  markUserAsDisconnected(project_id, client_id, callback) {
    logger.log({ project_id, client_id }, 'marking user as disconnected')
    const multi = rclient.multi()
    multi.srem(Keys.clientsInProject({ project_id }), client_id)
    multi.expire(Keys.clientsInProject({ project_id }), FOUR_DAYS_IN_S)
    multi.del(Keys.connectedUser({ project_id, client_id }))
    multi.exec(callback)
  },

  _getConnectedUser(project_id, client_id, callback) {
    rclient.hgetall(Keys.connectedUser({ project_id, client_id }), function (
      err,
      result
    ) {
      if (!(result && result.user_id)) {
        result = {
          connected: false,
          client_id
        }
      } else {
        result.connected = true
        result.client_id = client_id
        result.client_age =
          (Date.now() - parseInt(result.last_updated_at, 10)) / 1000
        if (result.cursorData) {
          try {
            result.cursorData = JSON.parse(result.cursorData)
          } catch (e) {
            logger.error(
              {
                err: e,
                project_id,
                client_id,
                cursorData: result.cursorData
              },
              'error parsing cursorData JSON'
            )
            return callback(e)
          }
        }
      }
      callback(err, result)
    })
  },

  getConnectedUsers(project_id, callback) {
    const self = this
    rclient.smembers(Keys.clientsInProject({ project_id }), function (
      err,
      results
    ) {
      if (err) {
        return callback(err)
      }
      const jobs = results.map((client_id) => (cb) =>
        self._getConnectedUser(project_id, client_id, cb)
      )
      async.series(jobs, function (err, users) {
        if (err) {
          return callback(err)
        }
        users = users.filter(
          (user) =>
            user && user.connected && user.client_age < REFRESH_TIMEOUT_IN_S
        )
        callback(null, users)
      })
    })
  }
}