uci-socket/src/socket.js

import { Server } from 'net'
import { unlink as fileDelete } from 'fs'
import { promisify } from 'util'
import path from 'path'
import mkdir from 'make-dir'
import btc from 'better-try-catch'
import _ON_DEATH from 'death' //this is intentionally ugly
import JSONStream from './json-stream'
import clone from 'clone'

// import logger from '../../uci-logger/src/logger'
import logger from '@uci/logger'
let log = {}

// TODO change default pipe dir for windows and mac os
const DEFAULT_PIPE_DIR = (process.env.SOCKETS_DIR || '/tmp/UCI')
const DEFAULT_SOCKET_NAME = 'uci-sock'

export default class Socket extends Server {
  constructor (opts={}) {
    super()
    this.id = opts.id || opts.name || 'socket:'+ new Date().getTime()
    if (!opts.path) {
      opts.host = opts.host || '0.0.0.0'
      opts.port = opts.port || 8080
    } else {
      if (typeof opts.path === 'boolean') opts.path = path.join(DEFAULT_PIPE_DIR,DEFAULT_SOCKET_NAME )
      if (path.dirname(opts.path)==='.') opts.path = path.join(DEFAULT_PIPE_DIR,opts.path )
    }
    this.clientTracking = opts.clientTracking || true
    this.clients = []  // track consumers (i.e. clients)
    this.opts = opts  // for use to recover from selected errors
    //self bindings
    this._listen = this._listen.bind(this)
    this.create = this.create.bind(this)
    log = logger({file:'src/socket.js',class:'Socket',name:'socket',id:this.id})
  } // end constructor

  async create () {

    return new Promise( async (resolve,reject) => {
      // couple ways to kill socket process when needed
      _ON_DEATH( async () => {
        log.info('\nhe\'s dead jim')
        await this._destroy()
      })
      process.once('SIGUSR2', async () => {
        await this._destroy
        process.kill(process.pid, 'SIGUSR2')
      })

      this.once('error', async (err) => {
        // recover from socket file that was not removed
        if (err.code === 'EADDRINUSE') {
          if (this.opts.path) { // if TCP socket should already be dead
            let [err, res] = log.info(await btc(promisify(fileDelete))(this.opts.path))
            if(!err) {
              log.info({res:res, socket: this.opts.path}, 'socket already exists.....deleted')
              return await this._listen(this.opts)
            }
            log.fatal({err:err},'error deleting socket.  Can not establish a socket')
            return err
          }
        }
        if (err.code ==='EACCES'){
          console.log({socket: this.opts.path}, 'directory does not exist...creating')
          await mkdir(path.dirname(this.opts.path))
          console.log({socket: this.opts.path}, 'created')
          log.warn({socket: this.opts.path}, 'directory does not exist...creating')
          return await this._listen(this.opts)
        }
        // otherwise fatally exit
        log.info(err, 'creating socket')
        reject(err)
      })

      let [err, res] = await btc(this._listen)(this.opts)
      if (err) reject(err)
      resolve(res)

    }) // end creeate promise
  } // end create

  registerPacketProcessor (func) {
    this._packetProcess = func
  }

  async _listen (opts) {
    super.listen(opts, async (err, res) => {
      if (err) return err
      // this gets called for each client connection and is unique to each
      this.on('connection', async (socket) => {
        const stream = new JSONStream()
        socket.stream = stream // need this to track clients
        let send = this._send.bind(socket)
        if (this.clientTracking) this.clients.push(socket)
        // TODO add 'close' listener to socket to remove from this.clients
        log.info('new consumer connecting')
        log.info(await send(await stream.serialize({'_handshake':true})))
        socket.on('data', stream.onData)
        // TODO need to start error listener for stream so errors can be processed
        stream.on('message', messageProcess.bind(this,socket))

        async function messageProcess (client, packet) {
          log.info({packet:packet},'incoming packet on socket side')
          let res = {}
          if (this.clientTracking && packet.clientID) {
            client.ID = packet.clientID
            res.cmd='ackID'
          }
          else {
            res = await this._packetProcess(clone(packet)) || {}
            if (Object.keys(res).length === 0) res = { error: 'socket packet command function likely did not return a promise', packet:packet}
          }
          if (packet) {
            res._header = clone(packet._header,false) || {} //make sure return packet has header with id in case it was removed in processing
            delete packet._header  // remove before adding to response header as request
          } else res._header = {}
          res._header.request = clone(packet,false)
          res._header.responder = {name:this.name,instanceID:this.id}
          res._header.socket = this.address()
          if (!res.cmd) res.cmd = 'reply'  // by default return command is 'reply'
          let [err, ser] = await btc(stream.serialize)(res)
          if (err) ser = await stream.serialize({ error: 'was not able to serialze the res packet', err:err, _header:{id:res._header.id}})
          log.info(await send(ser))
        } // end process message

      }) // end connecttion consumer
      log.info({opts: this.opts},'socket created')
      return res
    }) // end super listen callback

  } // end listen

  async _destroy () {
    log.info('closing down socket')
    await this.close()
    log.info('all connections closed....exiting')
    process.exit()
  }

  // default packet process, just a simple echo
  async _packetProcess (packet) {
    return new Promise(resolve => {
      resolve(packet)
    })
  }

  // must have a consumer socket bound to use
  async _send(packet) {
    // timeout already set if sockect can't be drained in 10 secs
    return new Promise(resolve => {
      const cb = () => resolve('packet written to socket stream')
      if (!this.write(packet)) {
        this.once('drain',cb )
      } else {
        process.nextTick(cb)
      }
    })
  }

  async push (packet,id) {
    packet._header = { id:'pushed'}
    this.clients.forEach(async (client) => {
      if (client.writable) {
        let [err, ser] = await btc(client.stream.serialize)(packet)
        if (err) ser = await client.stream.serialize({ error: 'was not able to serialze the res packet', err:err, _header:{id:packet._header.id}})
        if (!id || id ===client.ID ) await this._send.bind(client)(ser)
      }
    })
  }

} // end class