feat!: ping peers before adding to routing table (#2745)

Implements the [check-before-add](https://github.com/libp2p/go-libp2p-kad-dht/blob/master/optimizations.md#checking-before-adding)
client optimisation to ping a peer before adding it to the routing
table.

Adds a "new peer ping queue" to apply a concurrency limit to these
pings, because it would be expected for old contacts to be less
likely to be online so don't block adding new contacts to unrelated
buckets if the connection to an old contact is timing out while
being pinged before eviction.

BREAKING CHANGE: the routing ping options have been split into "old contact" and "new contact" and renamed according

Author: achingbrain

packages/kad-dht/package.json

@@ -109,7 +109,6 @@
     "lodash.random": "^3.2.0",
     "lodash.range": "^3.2.0",
     "p-retry": "^6.2.0",
-    "p-wait-for": "^5.0.2",
     "protons": "^7.5.0",
     "sinon": "^18.0.0",
     "sinon-ts": "^2.0.0",

packages/kad-dht/src/index.ts

@@ -400,15 +400,43 @@ export interface KadDHTInit {
    * Settings for how long to wait in ms when pinging DHT peers to decide if
    * they should be evicted from the routing table or not.
    */
-  pingTimeout?: Omit<AdaptiveTimeoutInit, 'metricsName' | 'metrics'>
+  pingOldContactTimeout?: Omit<AdaptiveTimeoutInit, 'metricsName' | 'metrics'>
 
   /**
    * How many peers to ping in parallel when deciding if they should
    * be evicted from the routing table or not
    *
    * @default 10
    */
-  pingConcurrency?: number
+  pingOldContactConcurrency?: number
+
+  /**
+   * How long the queue to ping peers is allowed to grow
+   *
+   * @default 100
+   */
+  pingOldContactMaxQueueSize?: number
+
+  /**
+   * Settings for how long to wait in ms when pinging DHT peers to decide if
+   * they should be added to the routing table or not.
+   */
+  pingNewContactTimeout?: Omit<AdaptiveTimeoutInit, 'metricsName' | 'metrics'>
+
+  /**
+   * How many peers to ping in parallel when deciding if they should be added to
+   * the routing table or not
+   *
+   * @default 10
+   */
+  pingNewContactConcurrency?: number
+
+  /**
+   * How long the queue to ping peers is allowed to grow
+   *
+   * @default 100
+   */
+  pingNewContactMaxQueueSize?: number
 
   /**
    * How many parallel incoming streams to allow on the DHT protocol per

packages/kad-dht/src/kad-dht.ts

@@ -138,8 +138,6 @@ export class KadDHT extends TypedEventEmitter<PeerDiscoveryEvents> implements Ka
       querySelfInterval,
       protocol,
       logPrefix,
-      pingTimeout,
-      pingConcurrency,
       maxInboundStreams,
       maxOutboundStreams,
       providers: providersInit
@@ -156,15 +154,6 @@ export class KadDHT extends TypedEventEmitter<PeerDiscoveryEvents> implements Ka
     this.maxInboundStreams = maxInboundStreams ?? DEFAULT_MAX_INBOUND_STREAMS
     this.maxOutboundStreams = maxOutboundStreams ?? DEFAULT_MAX_OUTBOUND_STREAMS
     this.peerInfoMapper = init.peerInfoMapper ?? removePrivateAddressesMapper
-    this.routingTable = new RoutingTable(components, {
-      kBucketSize,
-      pingTimeout,
-      pingConcurrency,
-      protocol: this.protocol,
-      logPrefix: loggingPrefix,
-      prefixLength: init.prefixLength,
-      splitThreshold: init.kBucketSplitThreshold
-    })
 
     this.providers = new Providers(components, providersInit ?? {})
 
@@ -181,6 +170,21 @@ export class KadDHT extends TypedEventEmitter<PeerDiscoveryEvents> implements Ka
       logPrefix: loggingPrefix
     })
 
+    this.routingTable = new RoutingTable(components, {
+      kBucketSize,
+      pingOldContactTimeout: init.pingOldContactTimeout,
+      pingOldContactConcurrency: init.pingOldContactConcurrency,
+      pingOldContactMaxQueueSize: init.pingOldContactMaxQueueSize,
+      pingNewContactTimeout: init.pingNewContactTimeout,
+      pingNewContactConcurrency: init.pingNewContactConcurrency,
+      pingNewContactMaxQueueSize: init.pingNewContactMaxQueueSize,
+      protocol: this.protocol,
+      logPrefix: loggingPrefix,
+      prefixLength: init.prefixLength,
+      splitThreshold: init.kBucketSplitThreshold,
+      network: this.network
+    })
+
     // all queries should wait for the initial query-self query to run so we have
     // some peers and don't force consumers to use arbitrary timeouts
     const initialQuerySelfHasRun = pDefer<any>()
@@ -376,11 +380,17 @@ export class KadDHT extends TypedEventEmitter<PeerDiscoveryEvents> implements Ka
 
     await this.components.registrar.unhandle(this.protocol)
 
+    // check again after async work
+    if (mode === this.getMode() && !force) {
+      this.log('already in %s mode', mode)
+      return
+    }
+
     if (mode === 'client') {
-      this.log('enabling client mode')
+      this.log('enabling client mode while in %s mode', this.getMode())
       this.clientMode = true
     } else {
-      this.log('enabling server mode')
+      this.log('enabling server mode while in %s mode', this.getMode())
       this.clientMode = false
       await this.components.registrar.handle(this.protocol, this.rpc.onIncomingStream.bind(this.rpc), {
         maxInboundStreams: this.maxInboundStreams,
@@ -399,14 +409,18 @@ export class KadDHT extends TypedEventEmitter<PeerDiscoveryEvents> implements Ka
     await this.setMode(this.clientMode ? 'client' : 'server', true)
 
     await start(
-      this.querySelf,
+      this.routingTable,
       this.providers,
       this.queryManager,
       this.network,
-      this.routingTable,
       this.topologyListener,
       this.routingTableRefresh
     )
+
+    // Query self after other components are configured
+    await start(
+      this.querySelf
+    )
   }
 
   /**

packages/kad-dht/src/network.ts

@@ -85,7 +85,7 @@ export class Network extends TypedEventEmitter<NetworkEvents> implements Startab
   }
 
   /**
-   * Send a request and record RTT for latency measurements
+   * Send a request and read a response
    */
   async * sendRequest (to: PeerId, msg: Partial<Message>, options: RoutingOptions = {}): AsyncGenerator<QueryEvent> {
     if (!this.running) {
@@ -204,7 +204,6 @@ export class Network extends TypedEventEmitter<NetworkEvents> implements Startab
   async _writeMessage (stream: Stream, msg: Partial<Message>, options: AbortOptions): Promise<void> {
     const pb = pbStream(stream)
     await pb.write(msg, Message, options)
-    await pb.unwrap().close(options)
   }
 
   /**
@@ -219,8 +218,6 @@ export class Network extends TypedEventEmitter<NetworkEvents> implements Startab
 
     const message = await pb.read(Message, options)
 
-    await pb.unwrap().close(options)
-
     // tell any listeners about new peers we've seen
     message.closer.forEach(peerData => {
       this.safeDispatchEvent<PeerInfo>('peer', {

packages/kad-dht/src/query-self.ts

@@ -106,19 +106,27 @@ export class QuerySelf implements Startable {
 
     if (this.started) {
       this.controller = new AbortController()
-      const timeoutSignal = AbortSignal.timeout(this.queryTimeout)
-      const signal = anySignal([this.controller.signal, timeoutSignal])
+      const signals = [this.controller.signal]
 
-      // this controller will get used for lots of dial attempts so make sure we don't cause warnings to be logged
-      setMaxListeners(Infinity, signal, this.controller.signal, timeoutSignal)
+      // add a shorter timeout if we've already run our initial self query
+      if (this.initialQuerySelfHasRun == null) {
+        const timeoutSignal = AbortSignal.timeout(this.queryTimeout)
+        setMaxListeners(Infinity, timeoutSignal)
+        signals.push(timeoutSignal)
+      }
+
+      const signal = anySignal(signals)
+      setMaxListeners(Infinity, signal, this.controller.signal)
 
       try {
         if (this.routingTable.size === 0) {
           this.log('routing table was empty, waiting for some peers before running query')
-          // wait to discover at least one DHT peer
+          // wait to discover at least one DHT peer that isn't us
           await pEvent(this.routingTable, 'peer:add', {
-            signal
+            signal,
+            filter: (event) => !this.peerId.equals(event.detail)
           })
+          this.log('routing table has peers, continuing with query')
         }
 
         this.log('run self-query, look for %d peers timing out after %dms', this.count, this.queryTimeout)