upring.js

'use strict'

const EE = require('events').EventEmitter
const inherits = require('util').inherits
const net = require('net')
const tentacoli = require('tentacoli')
const pump = require('pump')
const dezalgo = require('fastzalgo')
const networkAddress = require('network-address')
const bloomrun = require('bloomrun')
const pino = require('pino')
const tinysonic = require('tinysonic')
const promisify = require('util.promisify')
const avvio = require('avvio')
const Ajv = require('ajv')
const ajv = new Ajv({ coerceTypes: true })
const serializers = require('./lib/serializers')
const monitoring = require('./lib/monitoring')
const symbolSchema = Symbol('schema')

function UpRing (opts) {
  if (!(this instanceof UpRing)) {
    return new UpRing(opts)
  }

  opts = opts || {}
  opts.port = opts.port || 0
  opts.host = opts.host || networkAddress()

  const app = avvio(this)

  this._inbound = new Set()
  this.log = opts.logger ? opts.logger.child({ serializers }) : pino({ serializers })
  this.info = {}
  this._fireCallback = fireCallback.bind(this)
  this.isReady = false

  if (!opts.logger) {
    this.log.level = opts.logLevel || 'info'
  }

  this
    .use(require('./lib/tcp-server'), opts)
    .use(require('./lib/hashring'), opts)

  // for some reasons, ready() will not
  // work to set isReady
  app.use((i, opts, cb) => {
    this.isReady = true
    cb()
  })

  app.on('start', () => {
    this.emit('up')
  })

  this._dispatch = (req, reply) => {
    if (!this.isReady) {
      this.once('up', this._dispatch.bind(this, req, reply))
      return
    }

    var func
    this.emit('prerequest', req)
    if (this._router) {
      func = this._router.lookup(req)
      if (func) {
        if (func[symbolSchema]) {
          var valid = func[symbolSchema](req)
          if (valid !== true) {
            return reply(new Error('400'), valid)
          }
        }

        var result = func(req, reply)
        if (result && typeof result.then === 'function') {
          result
            .then(res => process.nextTick(reply, null, res))
            .catch(err => process.nextTick(reply, err, null))
        }
      } else {
        reply(new Error('message does not match any pattern'))
      }
    } else {
      this.emit('request', req, reply)
    }
  }

  this._peers = {}

  this.onClose(function (that, cb) {
    if (that._tracker) {
      that._tracker.clear()
    }

    Object.keys(that._peers).forEach((id) => {
      that._peers[id].destroy()
    })

    that._inbound.forEach((s) => {
      s.destroy()
    })

    that._hashring.close()

    that._server.close((err) => {
      that.log.info('closed')
      that.emit('close')
      cb(err)
    })
  })
}

inherits(UpRing, EE)

UpRing.prototype.whoami = function () {
  if (!this.isReady) throw new Error('UpRing not ready yet')
  return this._hashring.whoami()
}

UpRing.prototype.join = function (peers, cb) {
  if (!this.isReady) {
    this.once('up', this.join.bind(this, peers, cb))
    return
  }

  if (!Array.isArray(peers)) {
    peers = [peers]
  }
  return this._hashring.swim.join(peers, cb)
}

UpRing.prototype.allocatedToMe = function (key) {
  if (!this.isReady) return null
  return this._hashring.allocatedToMe(key)
}

UpRing.prototype.peerConn = function (peer) {
  let conn = this._peers[peer.id]

  if (!conn) {
    this.log.debug({ peer: peer }, 'connecting to peer')
    const upring = peer.meta.upring
    const stream = net.connect(upring.port, upring.address)
    conn = setupConn(this, peer, stream)
  }

  return conn
}

function setupConn (that, peer, stream, retry) {
  const conn = tentacoli()

  pump(stream, conn, stream, function () {
    that.log.debug({ peer: peer }, 'peer disconnected')
    var nustream = null
    that._hashring.on('peerDown', onPeerDown)

    if (!retry) {
      that.log.debug({ peer: peer }, 'reconnecting to peer')
      nustream = net.connect(peer.meta.upring.port, peer.meta.upring.address)
      nustream.on('connect', onConnect)
      nustream.on('error', onError)
    }

    function onPeerDown (peerDown) {
      if (peerDown.id === peer.id) {
        that.log.debug({ peer: peer }, 'peer down')
        delete that._peers[peer.id]
        that._hashring.removeListener('peerDown', onPeerDown)
        if (nustream) {
          nustream.destroy()
        }
      }
    }

    function onConnect () {
      that.log.debug({ peer: peer }, 'reconnected')
      setupConn(that, peer, nustream, true)
      that._hashring.removeListener('peerDown', onPeerDown)
    }

    function onError () {
      // do nothing, let's wait for peerDown
      // TODO that might never come, how to signal the hashring?
    }
  })

  setTimeout(function () {
    retry = true
  }, 10 * 1000).unref() // 10 seconds

  that._peers[peer.id] = conn
  return conn
}

UpRing.prototype.peers = function (myself) {
  return this._hashring.peers(myself)
}

UpRing.prototype.mymeta = function () {
  return this._hashring.mymeta()
}

UpRing.prototype.request = function (obj, callback, _count) {
  if (!this.isReady) {
    this.once('up', this.request.bind(this, obj, callback))
    return
  }

  if (this._hashring.allocatedToMe(obj.key)) {
    this.log.trace({ msg: obj }, 'local call')
    this._dispatch(obj, dezalgo(callback))
  } else {
    const peer = this._hashring.lookup(obj.key)
    this.log.trace({ msg: obj, peer }, 'remote call')

    const upring = peer.meta.upring
    if (!upring || !upring.address || !upring.port) {
      callback(new Error('peer has invalid upring metadata'))
      return
    }

    // TODO simplify all this logic
    // and avoid allocating a closure
    if (typeof _count !== 'number') {
      _count = 0
    } else if (_count === 3) {
      callback(new Error('retried three times'))
      return
    } else {
      _count++
    }

    const conn = this.peerConn(peer)

    if (conn.destroyed) {
      // TODO make this dependent on the gossip interval
      setTimeout(retry, 500, this, 'request', obj, callback, _count)
      return
    }

    conn.request(obj, (err, result) => {
      if (err) {
        // the peer has changed
        if (this._hashring.lookup(obj.key).id !== peer.id || conn.destroyed) {
          // TODO make this dependent on the gossip interval
          setTimeout(retry, 500, this, 'request', obj, callback, _count)
          return
        }
      }
      callback(err, result)
    })
  }

  return this
}

UpRing.prototype.requestp = promisify(UpRing.prototype.request)

UpRing.prototype.fire = function (obj, callback, _count) {
  callback = callback || this._fireCallback
  if (!this.isReady) {
    this.once('up', this.fire.bind(this, obj, callback))
    return
  }

  if (this._hashring.allocatedToMe(obj.key)) {
    this.log.trace({ msg: obj }, 'local call')
    callback()
    this._dispatch(obj, noop)
  } else {
    const peer = this._hashring.lookup(obj.key)
    this.log.trace({ msg: obj, peer }, 'remote call')

    const upring = peer.meta.upring
    if (!upring || !upring.address || !upring.port) {
      callback(new Error('peer has invalid upring metadata'))
      return
    }

    // TODO simplify all this logic
    // and avoid allocating a closure
    if (typeof _count !== 'number') {
      _count = 0
    } else if (_count === 3) {
      callback(new Error('retried three times'))
      return
    } else {
      _count++
    }

    const conn = this.peerConn(peer)

    if (conn.destroyed) {
      // TODO make this dependent on the gossip interval
      setTimeout(retry, 500, this, 'fire', obj, callback, _count)
      return
    }

    conn.fire(obj, (err) => {
      if (err) {
        // the peer has changed
        if (this._hashring.lookup(obj.key).id !== peer.id || conn.destroyed) {
          // TODO make this dependent on the gossip interval
          setTimeout(retry, 500, this, 'fire', obj, callback, _count)
          return
        }
      }
      callback(err)
    })
  }

  return this
}

function fireCallback (err) {
  if (err) {
    this.log.debug(err, 'fire and forget')
  }
}

function retry (that, method, obj, callback, _count) {
  that[method](obj, callback, _count)
}

UpRing.prototype.add = function (pattern, schema, func) {
  if (!this._router) {
    this._router = bloomrun()
    monitoring(this)
  }

  if (typeof schema === 'function') {
    func = schema
    schema = null
  }

  func[symbolSchema] = schema === null ? null : ajv.compile(schema)

  if (typeof pattern === 'string') {
    let sonic = tinysonic(pattern)

    if (sonic) {
      pattern = sonic
    } else {
      pattern = { cmd: pattern }
    }
  }

  this._router.add(pattern, func)
}

function noop () {}

module.exports = UpRing