kafkajs/src/network/requestQueue/socketRequest.js

A modern Apache Kafka client for node.js

const { KafkaJSRequestTimeoutError, KafkaJSNonRetriableError } = require('../../errors')
const events = require('../instrumentationEvents')

const PRIVATE = {
  STATE: Symbol('private:SocketRequest:state'),
  EMIT_EVENT: Symbol('private:SocketRequest:emitEvent'),
}

const REQUEST_STATE = {
  PENDING: Symbol('PENDING'),
  SENT: Symbol('SENT'),
  COMPLETED: Symbol('COMPLETED'),
  REJECTED: Symbol('REJECTED'),
}

/**
 * SocketRequest abstracts the life cycle of a socket request, making it easier to track
 * request durations and to have individual timeouts per request.
 *
 * @typedef {Object} SocketRequest
 * @property {number} createdAt
 * @property {number} sentAt
 * @property {number} pendingDuration
 * @property {number} duration
 * @property {number} requestTimeout
 * @property {string} broker
 * @property {string} clientId
 * @property {RequestEntry} entry
 * @property {boolean} expectResponse
 * @property {Function} send
 * @property {Function} timeout
 *
 * @typedef {Object} RequestEntry
 * @property {string} apiKey
 * @property {string} apiName
 * @property {number} apiVersion
 * @property {number} correlationId
 * @property {Function} resolve
 * @property {Function} reject
 */
module.exports = class SocketRequest {
  /**
   * @param {Object} options
   * @param {number} options.requestTimeout
   * @param {string} options.broker - e.g: 127.0.0.1:9092
   * @param {string} options.clientId
   * @param {RequestEntry} options.entry
   * @param {boolean} options.expectResponse
   * @param {Function} options.send
   * @param {() => void} options.timeout
   * @param {import("../../instrumentation/emitter")} [options.instrumentationEmitter=null]
   */
  constructor({
    requestTimeout,
    broker,
    clientId,
    entry,
    expectResponse,
    send,
    timeout,
    instrumentationEmitter = null,
  }) {
    this.createdAt = Date.now()
    this.requestTimeout = requestTimeout
    this.broker = broker
    this.clientId = clientId
    this.entry = entry
    this.correlationId = entry.correlationId
    this.expectResponse = expectResponse
    this.sendRequest = send
    this.timeoutHandler = timeout

    this.sentAt = null
    this.duration = null
    this.pendingDuration = null

    this[PRIVATE.STATE] = REQUEST_STATE.PENDING
    this[PRIVATE.EMIT_EVENT] = (eventName, payload) =>
      instrumentationEmitter && instrumentationEmitter.emit(eventName, payload)
  }

  send() {
    this.throwIfInvalidState({
      accepted: [REQUEST_STATE.PENDING],
      next: REQUEST_STATE.SENT,
    })

    this.sendRequest()
    this.sentAt = Date.now()
    this.pendingDuration = this.sentAt - this.createdAt
    this[PRIVATE.STATE] = REQUEST_STATE.SENT
  }

  timeoutRequest() {
    const { apiName, apiKey, apiVersion } = this.entry
    const requestInfo = `${apiName}(key: ${apiKey}, version: ${apiVersion})`
    const eventData = {
      broker: this.broker,
      clientId: this.clientId,
      correlationId: this.correlationId,
      createdAt: this.createdAt,
      sentAt: this.sentAt,
      pendingDuration: this.pendingDuration,
    }

    this.timeoutHandler()
    this.rejected(new KafkaJSRequestTimeoutError(`Request ${requestInfo} timed out`, eventData))
    this[PRIVATE.EMIT_EVENT](events.NETWORK_REQUEST_TIMEOUT, {
      ...eventData,
      apiName,
      apiKey,
      apiVersion,
    })
  }

  completed({ size, payload }) {
    this.throwIfInvalidState({
      accepted: [REQUEST_STATE.SENT],
      next: REQUEST_STATE.COMPLETED,
    })

    const { entry, correlationId, broker, clientId, createdAt, sentAt, pendingDuration } = this

    this[PRIVATE.STATE] = REQUEST_STATE.COMPLETED
    this.duration = Date.now() - this.sentAt
    entry.resolve({ correlationId, entry, size, payload })

    this[PRIVATE.EMIT_EVENT](events.NETWORK_REQUEST, {
      broker,
      clientId,
      correlationId,
      size,
      createdAt,
      sentAt,
      pendingDuration,
      duration: this.duration,
      apiName: entry.apiName,
      apiKey: entry.apiKey,
      apiVersion: entry.apiVersion,
    })
  }

  rejected(error) {
    this.throwIfInvalidState({
      accepted: [REQUEST_STATE.PENDING, REQUEST_STATE.SENT],
      next: REQUEST_STATE.REJECTED,
    })

    this[PRIVATE.STATE] = REQUEST_STATE.REJECTED
    this.duration = Date.now() - this.sentAt
    this.entry.reject(error)
  }

  /**
   * @private
   */
  throwIfInvalidState({ accepted, next }) {
    if (accepted.includes(this[PRIVATE.STATE])) {
      return
    }

    const current = this[PRIVATE.STATE].toString()

    throw new KafkaJSNonRetriableError(
      `Invalid state, can't transition from ${current} to ${next.toString()}`
    )
  }
}