uci-socket/src/socket.js

import { Server } from 'net'
import { unlink as fileDelete } from 'fs'
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.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
            log.warn({socket: this.opts.path}, 'socket already exists...deleting')
            await fileDelete(this.opts.path)
            return await this._listen(this.opts)
          }
        }
        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) => {
        let write = this._write.bind(socket)
        const stream = new JSONStream()
        log.info('new consumer connecting sending handshake')
        write(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))
        async function messageProcess (packet) {
          //console.log(' incoming packet on socket side',packet)
          let 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}
          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
          res._header.request = clone(packet,false)
          res._header.responder = {name:this.name,instanceID:this.id}
          res._header.socket = this._connectionKey
          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}})
          // console.log('serialized ready for write',ser)
          log.info(await write(ser))
        }
      }) // 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 _write(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)
      }
    })
  }

} // end class