feat: async peerstore backed by datastores (#1058)

We have a peerstore that keeps all data for all observed peers in memory with no eviction.

This is fine when you don't discover many peers but when using the DHT you encounter a significant number of peers so our peer storage grows and grows over time.

We have a persistent peer store, but it just periodically writes peers into the datastore to be read at startup, still keeping them in memory.

It also means a restart doesn't give you any temporary reprieve from the memory leak as the previously observed peer data is read into memory at startup.

This change refactors the peerstore to use a datastore by default, reading and writing peer info as it arrives.  It can be configured with a MemoryDatastore if desired.

It was necessary to change the peerstore and *book interfaces to be asynchronous since the datastore api is asynchronous.

BREAKING CHANGE: `libp2p.handle`, `libp2p.registrar.register` and the peerstore methods have become async

test/ts-use/package.json

@@ -2,17 +2,17 @@
   "name": "ts-use",
   "private": true,
   "dependencies": {
-    "datastore-level": "^6.0.0",
-    "ipfs-http-client": "^50.1.2",
+    "@achingbrain/libp2p-gossipsub": "^0.12.2",
+    "@chainsafe/libp2p-noise": "^5.0.0",
+    "datastore-level": "^7.0.1",
+    "ipfs-http-client": "^55.0.0",
     "libp2p": "file:../..",
-    "libp2p-bootstrap": "^0.13.0",
+    "libp2p-bootstrap": "^0.14.0",
     "libp2p-delegated-content-routing": "^0.11.0",
     "libp2p-delegated-peer-routing": "^0.11.1",
-    "libp2p-gossipsub": "^0.9.0",
-    "libp2p-interfaces": "^1.0.1",
-    "libp2p-kad-dht": "^0.26.5",
+    "libp2p-interfaces": "^4.0.0",
+    "libp2p-kad-dht": "^0.28.6",
     "libp2p-mplex": "^0.10.4",
-    "@chainsafe/libp2p-noise": "^4.1.0",
     "libp2p-record": "^0.10.4",
     "libp2p-tcp": "^0.17.1",
     "libp2p-websockets": "^0.16.1",

test/ts-use/src/main.ts

@@ -105,8 +105,7 @@ async function main() {
     },
     datastore: new LevelStore('path/to/store'),
     peerStore: {
-      persistence: false,
-      threshold: 5
+      persistence: false
     },
     keychain: {
       pass: 'notsafepassword123456789',