From 7383821e1a4bab17ee56a55c78d523e918db0bcc Mon Sep 17 00:00:00 2001
From: Alex Potsides <alex@achingbrain.net>
Date: Fri, 25 Oct 2024 17:48:12 +0100
Subject: [PATCH] fix: remove peer cache (#2786)

In cases where the peer store has grown very large (e.g. when a
well connected node has been online for a long time), the peer store
can get so large that this cache causes abnormal memory use.

The cache was added without any profiling, remove the cache for now,
we can add it back if it actually solves a problem
---
 packages/peer-store/package.json |  1 -
 packages/peer-store/src/store.ts | 27 +++++++--------------------
 2 files changed, 7 insertions(+), 21 deletions(-)

diff --git a/packages/peer-store/package.json b/packages/peer-store/package.json
index 675a552e36..6218bb733f 100644
--- a/packages/peer-store/package.json
+++ b/packages/peer-store/package.json
@@ -61,7 +61,6 @@
   "dependencies": {
     "@libp2p/crypto": "^5.0.5",
     "@libp2p/interface": "^2.1.3",
-    "@libp2p/peer-collections": "^6.0.9",
     "@libp2p/peer-id": "^5.0.6",
     "@libp2p/peer-record": "^8.0.9",
     "@multiformats/multiaddr": "^12.2.3",
diff --git a/packages/peer-store/src/store.ts b/packages/peer-store/src/store.ts
index 042addf9e5..715b88232e 100644
--- a/packages/peer-store/src/store.ts
+++ b/packages/peer-store/src/store.ts
@@ -1,5 +1,4 @@
 import { InvalidParametersError } from '@libp2p/interface'
-import { PeerMap } from '@libp2p/peer-collections'
 import { peerIdFromCID } from '@libp2p/peer-id'
 import mortice, { type Mortice } from 'mortice'
 import { base32 } from 'multiformats/bases/base32'
@@ -20,26 +19,16 @@ export interface PeerUpdate extends PeerUpdateExternal {
   updated: boolean
 }
 
-function decodePeer (key: Key, value: Uint8Array, cache: PeerMap<Peer>): Peer {
+function decodePeer (key: Key, value: Uint8Array): Peer {
   // /peers/${peer-id-as-libp2p-key-cid-string-in-base-32}
   const base32Str = key.toString().split('/')[2]
   const buf = CID.parse(base32Str, base32)
   const peerId = peerIdFromCID(buf)
 
-  const cached = cache.get(peerId)
-
-  if (cached != null) {
-    return cached
-  }
-
-  const peer = bytesToPeer(peerId, value)
-
-  cache.set(peerId, peer)
-
-  return peer
+  return bytesToPeer(peerId, value)
 }
 
-function mapQuery (query: PeerQuery, cache: PeerMap<Peer>): Query {
+function mapQuery (query: PeerQuery): Query {
   if (query == null) {
     return {}
   }
@@ -47,10 +36,10 @@ function mapQuery (query: PeerQuery, cache: PeerMap<Peer>): Query {
   return {
     prefix: NAMESPACE_COMMON,
     filters: (query.filters ?? []).map(fn => ({ key, value }) => {
-      return fn(decodePeer(key, value, cache))
+      return fn(decodePeer(key, value))
     }),
     orders: (query.orders ?? []).map(fn => (a, b) => {
-      return fn(decodePeer(a.key, a.value, cache), decodePeer(b.key, b.value, cache))
+      return fn(decodePeer(a.key, a.value), decodePeer(b.key, b.value))
     })
   }
 }
@@ -131,10 +120,8 @@ export class PersistentStore {
   }
 
   async * all (query?: PeerQuery): AsyncGenerator<Peer, void, unknown> {
-    const peerCache = new PeerMap<Peer>()
-
-    for await (const { key, value } of this.datastore.query(mapQuery(query ?? {}, peerCache))) {
-      const peer = decodePeer(key, value, peerCache)
+    for await (const { key, value } of this.datastore.query(mapQuery(query ?? {}))) {
+      const peer = decodePeer(key, value)
 
       if (peer.id.equals(this.peerId)) {
         // Skip self peer if present