fix(kad-dht): run the periodic routing table refresh (libp2p#3538)

* test(kad-dht): cover the periodic routing table refresh

These fail against the current code: the periodic (non-forced) refresh never issues queries, and a just-refreshed prefix length is not throttled.

* fix(kad-dht): run the periodic routing table refresh

Never-refreshed prefix lengths defaulted to the current time, so the throttle always skipped them and only the startup refresh ran. Default to the epoch and record refresh times on success.

Author: tabcat

packages/kad-dht/src/routing-table/refresh.ts

@@ -148,6 +148,8 @@ export class RoutingTableRefresh {
 
       this.log(`found ${peers} peers that were close to imaginary peer %p`, peerId)
       this.log('finished refreshing cpl %s with key %p (routing table size is now %s)', cpl, peerId, this.routingTable.size)
+
+      this.commonPrefixLengthRefreshedAt[cpl] = new Date()
     } finally {
       signal.clear()
     }
@@ -162,7 +164,7 @@ export class RoutingTableRefresh {
 
     for (let i = 0; i <= maxCommonPrefix; i++) {
       // defaults to the zero value if we haven't refreshed it yet.
-      dates[i] = this.commonPrefixLengthRefreshedAt[i] ?? new Date()
+      dates[i] = this.commonPrefixLengthRefreshedAt[i] ?? new Date(0)
     }
 
     return dates

packages/kad-dht/test/routing-table.spec.ts

@@ -17,9 +17,12 @@ import { MessageType } from '../src/message/dht.ts'
 import { peerResponseEvent } from '../src/query/events.ts'
 import { KAD_PEER_TAG_NAME, KAD_PEER_TAG_VALUE, RoutingTable } from '../src/routing-table/index.ts'
 import { isLeafBucket } from '../src/routing-table/k-bucket.ts'
+import { RoutingTableRefresh } from '../src/routing-table/refresh.ts'
 import * as kadUtils from '../src/utils.ts'
 import { createPeerIdWithPrivateKey, createPeerIdsWithPrivateKey } from './utils/create-peer-id.ts'
+import type { QueryEvent } from '../src/index.ts'
 import type { Network } from '../src/network.ts'
+import type { PeerRouting } from '../src/peer-routing/index.ts'
 import type { RoutingTableComponents } from '../src/routing-table/index.ts'
 import type { Bucket } from '../src/routing-table/k-bucket.ts'
 import type { Libp2pEvents, PeerId, PeerStore, Peer } from '@libp2p/interface'
@@ -572,6 +575,51 @@ describe('Routing Table', () => {
     expect(table.kb.root).to.have.property('peers').that.is.empty()
   })
 
+  describe('refresh', () => {
+    let peerRouting: StubbedInstance<PeerRouting>
+    let refresh: RoutingTableRefresh
+    let queriedKeys: Uint8Array[]
+
+    beforeEach(() => {
+      queriedKeys = []
+      peerRouting = stubInterface<PeerRouting>()
+      peerRouting.getClosestPeers.callsFake((key: Uint8Array) => {
+        queriedKeys.push(key)
+        return (async function * (): AsyncGenerator<QueryEvent> {})()
+      })
+
+      refresh = new RoutingTableRefresh({ logger: defaultLogger() }, {
+        peerRouting,
+        routingTable: table,
+        logPrefix: ''
+      })
+    })
+
+    afterEach(async () => {
+      await refresh.stop()
+    })
+
+    it('issues refresh queries when run without force (the periodic refresh path)', async () => {
+      refresh.refreshTable(false)
+      await delay(200)
+
+      expect(queriedKeys.length).to.be.greaterThan(0)
+    })
+
+    it('does not re-query a common prefix length that was just refreshed', async () => {
+      refresh.refreshTable(false)
+      await delay(200)
+
+      const afterFirstRefresh = queriedKeys.length
+      expect(afterFirstRefresh).to.be.greaterThan(0)
+
+      refresh.refreshTable(false)
+      await delay(200)
+
+      expect(queriedKeys.length).to.equal(afterFirstRefresh)
+    })
+  })
+
   describe('max size', () => {
     it('should constrain size to 10', async () => {
       const prefixLength = 8