feat(rosenet-node, rosenet-relay): limit relays count for nodes

Connecting to a lot of relays can significantly affect pubsub network
traffic. For 40 nodes, 3 relay per node seems a good balance between
traffic, delivery and performance. This number may change in the future,
though.

Also prevent relays from broadcasting their addresses over discovery
network. If not disable, it totally negates the point of limiting relays
count to 3.

packages/rosenet-node/lib/createRoseNetNode.ts

@@ -23,6 +23,7 @@ import addressService from './address/address-service';
 import streamService from './stream/stream-service';
 
 import { decode, encode } from './utils/codec';
+import sample from './utils/sample';
 
 import RoseNetNodeError from './errors/RoseNetNodeError';
 
@@ -61,6 +62,11 @@ const createRoseNetNode = async ({
   const announceMultiaddr = await addressService.getAnnounceMultiaddr(port);
   logger.info(`${announceMultiaddr} set as announce multiaddr`);
 
+  const sampledRelayMultiaddrs = sample(
+    config.relayMultiaddrs,
+    RELAYS_COUNT_TO_CONNECT,
+  );
+
   const node = await createLibp2p({
     peerId,
     transports: [
@@ -72,13 +78,13 @@ const createRoseNetNode = async ({
     addresses: {
       listen: [
         `/ip4/0.0.0.0/tcp/${port}`,
-        ...config.relayMultiaddrs.map(
+        ...sampledRelayMultiaddrs.map(
           (multiaddr) => `${multiaddr}/p2p-circuit`,
         ),
       ],
       announce: [
         announceMultiaddr,
-        ...config.relayMultiaddrs.map(
+        ...sampledRelayMultiaddrs.map(
           (multiaddr) => `${multiaddr}/p2p-circuit`,
         ),
       ],
@@ -98,7 +104,7 @@ const createRoseNetNode = async ({
     streamMuxers: [yamux()],
     peerDiscovery: [
       bootstrap({
-        list: config.relayMultiaddrs,
+        list: sampledRelayMultiaddrs,
       }),
       pubsubPeerDiscovery(),
     ],

packages/rosenet-node/lib/utils/sample.ts

@@ -0,0 +1,13 @@
+/**
+ * Sample `size` elements from `array` randomly
+ * @param array
+ * @param size
+ */
+const sample = <T>(array: T[], size: number): T[] =>
+  array
+    .map((value) => ({ value, sort: Math.random() }))
+    .sort((a, b) => a.sort - b.sort)
+    .map(({ value }) => value)
+    .slice(0, size);
+
+export default sample;

packages/rosenet-relay/lib/createRoseNetRelay.ts

@@ -82,7 +82,7 @@ const createRoseNetRelay = async ({
       }),
       identify: identify(),
     },
-    peerDiscovery: [pubsubPeerDiscovery()],
+    peerDiscovery: [pubsubPeerDiscovery({ listenOnly: true })],
     nodeInfo: {
       name: 'rosenet-relay',
       version: packageJson.version,