refactor!: remove isStarted method from Startable (#2145)

We have an `isStarted` method on the `Startable` interface but we only
really use it in tests. Our implementations tend to guard on being
started twice so it just adds noise to every implementation.

BREAKING CHANGE: the `isStarted` method has been removed from the `Startable` interface

packages/interface-compliance-tests/src/pubsub/api.ts

@@ -48,7 +48,6 @@ export default (common: TestSetup<PubSub, PubSubArgs>): void => {
 
       await start(...Object.values(components))
 
-      expect(pubsub.isStarted()).to.equal(true)
       expect(components.registrar.register).to.have.property('callCount', 1)
     })
 
@@ -62,7 +61,6 @@ export default (common: TestSetup<PubSub, PubSubArgs>): void => {
       await start(...Object.values(components))
       await stop(...Object.values(components))
 
-      expect(pubsub.isStarted()).to.equal(false)
       expect(components.registrar.unregister).to.have.property('callCount', 1)
     })
 

packages/interface/src/startable.ts

@@ -2,8 +2,6 @@
  * Implemented by components that have a lifecycle
  */
 export interface Startable {
-  isStarted(): boolean
-
   /**
    * If implemented, this method will be invoked before the start method.
    *

packages/libp2p/test/identify/service.spec.ts

@@ -153,7 +153,6 @@ describe('identify', () => {
 
     // Wait for identify to finish
     await identityServiceIdentifySpy.firstCall.returnValue
-    sinon.stub(libp2p, 'isStarted').returns(true)
 
     // Cause supported protocols to change
     await libp2p.handle('/echo/2.0.0', () => {})
@@ -251,7 +250,6 @@ describe('identify', () => {
 
     // Wait for identify to finish
     await identityServiceIdentifySpy.firstCall.returnValue
-    sinon.stub(libp2p, 'isStarted').returns(true)
 
     await libp2p.peerStore.merge(libp2p.peerId, {
       multiaddrs: [multiaddr('/ip4/180.0.0.1/tcp/15001/ws')]

packages/libp2p/test/transports/transport-manager.spec.ts

@@ -124,7 +124,6 @@ describe('libp2p.transportManager (dial only)', () => {
       start: false
     })
 
-    expect(libp2p.isStarted()).to.be.false()
     await expect(libp2p.start()).to.eventually.be.rejected
       .with.property('code', ErrorCodes.ERR_NO_VALID_ADDRESSES)
   })
@@ -147,7 +146,6 @@ describe('libp2p.transportManager (dial only)', () => {
       start: false
     })
 
-    expect(libp2p.isStarted()).to.be.false()
     await expect(libp2p.start()).to.eventually.be.undefined()
   })
 
@@ -169,7 +167,6 @@ describe('libp2p.transportManager (dial only)', () => {
       start: false
     })
 
-    expect(libp2p.isStarted()).to.be.false()
     await expect(libp2p.start()).to.eventually.be.undefined()
   })
 })

packages/peer-discovery-mdns/src/index.ts

@@ -76,186 +76,9 @@
  * ```
  */
 
-import { CustomEvent, TypedEventEmitter } from '@libp2p/interface/events'
-import { peerDiscovery } from '@libp2p/interface/peer-discovery'
-import { logger } from '@libp2p/logger'
-import multicastDNS from 'multicast-dns'
-import * as query from './query.js'
-import { stringGen } from './utils.js'
-import type { PeerDiscovery, PeerDiscoveryEvents } from '@libp2p/interface/peer-discovery'
-import type { PeerInfo } from '@libp2p/interface/peer-info'
-import type { Startable } from '@libp2p/interface/src/startable.js'
-import type { AddressManager } from '@libp2p/interface-internal/address-manager'
-
-const log = logger('libp2p:mdns')
-
-export interface MulticastDNSInit {
-  /**
-   * (true/false) announce our presence through mDNS, default `true`
-   */
-  broadcast?: boolean
-
-  /**
-   * query interval, default 10 \* 1000 (10 seconds)
-   */
-  interval?: number
-
-  /**
-   * name of the service announce , default '_p2p._udp.local\`
-   */
-  serviceTag?: string
-  /**
-   * Peer name to announce (should not be peeer id), default random string
-   */
-  peerName?: string
-
-  /**
-   * UDP port to broadcast to
-   */
-  port?: number
-
-  /**
-   * UDP IP to broadcast to
-   */
-  ip?: string
-}
-
-export interface MulticastDNSComponents {
-  addressManager: AddressManager
-}
-
-class MulticastDNS extends TypedEventEmitter<PeerDiscoveryEvents> implements PeerDiscovery, Startable {
-  public mdns?: multicastDNS.MulticastDNS
-
-  private readonly broadcast: boolean
-  private readonly interval: number
-  private readonly serviceTag: string
-  private readonly peerName: string
-  private readonly port: number
-  private readonly ip: string
-  private _queryInterval: ReturnType<typeof setInterval> | null
-  private readonly components: MulticastDNSComponents
-
-  constructor (components: MulticastDNSComponents, init: MulticastDNSInit = {}) {
-    super()
-
-    this.broadcast = init.broadcast !== false
-    this.interval = init.interval ?? (1e3 * 10)
-    this.serviceTag = init.serviceTag ?? '_p2p._udp.local'
-    this.ip = init.ip ?? '224.0.0.251'
-    this.peerName = init.peerName ?? stringGen(63)
-    // 63 is dns label limit
-    if (this.peerName.length >= 64) {
-      throw new Error('Peer name should be less than 64 chars long')
-    }
-    this.port = init.port ?? 5353
-    this.components = components
-    this._queryInterval = null
-    this._onMdnsQuery = this._onMdnsQuery.bind(this)
-    this._onMdnsResponse = this._onMdnsResponse.bind(this)
-    this._onMdnsWarning = this._onMdnsWarning.bind(this)
-    this._onMdnsError = this._onMdnsError.bind(this)
-  }
-
-  readonly [peerDiscovery] = this
-
-  readonly [Symbol.toStringTag] = '@libp2p/mdns'
-
-  isStarted (): boolean {
-    return Boolean(this.mdns)
-  }
-
-  /**
-   * Start sending queries to the LAN.
-   *
-   * @returns {void}
-   */
-  async start (): Promise<void> {
-    if (this.mdns != null) {
-      return
-    }
-
-    this.mdns = multicastDNS({ port: this.port, ip: this.ip })
-    this.mdns.on('query', this._onMdnsQuery)
-    this.mdns.on('response', this._onMdnsResponse)
-    this.mdns.on('warning', this._onMdnsWarning)
-    this.mdns.on('error', this._onMdnsError)
-
-    this._queryInterval = query.queryLAN(this.mdns, this.serviceTag, this.interval)
-  }
-
-  _onMdnsQuery (event: multicastDNS.QueryPacket): void {
-    if (this.mdns == null) {
-      return
-    }
-
-    log.trace('received incoming mDNS query')
-    query.gotQuery(
-      event,
-      this.mdns,
-      this.peerName,
-      this.components.addressManager.getAddresses(),
-      this.serviceTag,
-      this.broadcast)
-  }
-
-  _onMdnsResponse (event: multicastDNS.ResponsePacket): void {
-    log.trace('received mDNS query response')
-
-    try {
-      const foundPeer = query.gotResponse(event, this.peerName, this.serviceTag)
-
-      if (foundPeer != null) {
-        log('discovered peer in mDNS query response %p', foundPeer.id)
-
-        this.dispatchEvent(new CustomEvent<PeerInfo>('peer', {
-          detail: foundPeer
-        }))
-      }
-    } catch (err) {
-      log.error('Error processing peer response', err)
-    }
-  }
-
-  _onMdnsWarning (err: Error): void {
-    log.error('mdns warning', err)
-  }
-
-  _onMdnsError (err: Error): void {
-    log.error('mdns error', err)
-  }
-
-  /**
-   * Stop sending queries to the LAN.
-   *
-   * @returns {Promise}
-   */
-  async stop (): Promise<void> {
-    if (this.mdns == null) {
-      return
-    }
-
-    this.mdns.removeListener('query', this._onMdnsQuery)
-    this.mdns.removeListener('response', this._onMdnsResponse)
-    this.mdns.removeListener('warning', this._onMdnsWarning)
-    this.mdns.removeListener('error', this._onMdnsError)
-
-    if (this._queryInterval != null) {
-      clearInterval(this._queryInterval)
-      this._queryInterval = null
-    }
-
-    await new Promise<void>((resolve) => {
-      if (this.mdns != null) {
-        this.mdns.destroy(resolve)
-      } else {
-        resolve()
-      }
-    })
-
-    this.mdns = undefined
-  }
-}
+import { MulticastDNS } from './mdns.js'
+import type { MulticastDNSInit, MulticastDNSComponents } from './mdns.js'
+import type { PeerDiscovery } from '@libp2p/interface/peer-discovery'
 
 export function mdns (init: MulticastDNSInit = {}): (components: MulticastDNSComponents) => PeerDiscovery {
   return (components: MulticastDNSComponents) => new MulticastDNS(components, init)