From ac9189c60614daca8340e9a42aa79b85103da552 Mon Sep 17 00:00:00 2001
From: Mitchell McCaffrey <mitchemmc@gmail.com>
Date: Mon, 6 Apr 2020 14:33:22 +1000
Subject: [PATCH] Added a sync option when connecting to peers

Optimises the user join time by not sending the image data multiple times
---
 src/helpers/useSession.js | 13 +++++++++----
 src/routes/Game.js        | 18 ++++++++++--------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/src/helpers/useSession.js b/src/helpers/useSession.js
index 21073d1..90f0ac9 100644
--- a/src/helpers/useSession.js
+++ b/src/helpers/useSession.js
@@ -14,7 +14,7 @@ function useSession(partyId, onPeerConnected, onPeerDisconnected, onPeerData) {
   const [peers, setPeers] = useState({});
 
   useEffect(() => {
-    function addPeer(id, initiator) {
+    function addPeer(id, initiator, sync) {
       const peer = new Peer({ initiator, trickle: false });
 
       peer.on("signal", (signal) => {
@@ -23,6 +23,9 @@ function useSession(partyId, onPeerConnected, onPeerDisconnected, onPeerData) {
 
       peer.on("connect", () => {
         onPeerConnected && onPeerConnected({ id, peer, initiator });
+        if (sync) {
+          peer.send({ id: "sync" });
+        }
       });
 
       peer.on("dataComplete", (data) => {
@@ -45,7 +48,7 @@ function useSession(partyId, onPeerConnected, onPeerDisconnected, onPeerData) {
     }
 
     function handlePartyMemberJoined(id) {
-      addPeer(id, false);
+      addPeer(id, false, false);
     }
 
     function handlePartyMemberLeft(id) {
@@ -56,8 +59,10 @@ function useSession(partyId, onPeerConnected, onPeerDisconnected, onPeerData) {
     }
 
     function handleJoinedParty(otherIds) {
-      for (let id of otherIds) {
-        addPeer(id, true);
+      for (let [index, id] of otherIds.entries()) {
+        // Send a sync request to the first member of the party
+        const sync = index === 0;
+        addPeer(id, true, sync);
       }
     }
 
diff --git a/src/routes/Game.js b/src/routes/Game.js
index d5c35d7..3fb858e 100644
--- a/src/routes/Game.js
+++ b/src/routes/Game.js
@@ -70,17 +70,19 @@ function Game() {
     }
   }
 
-  function handlePeerConnected({ peer, initiator }) {
-    if (!initiator) {
-      if (mapSource) {
-        peer.send({ id: "map", data: mapDataRef.current });
-      }
-      peer.send({ id: "tokenEdit", data: mapTokens });
-    }
+  function handlePeerConnected({ peer }) {
     peer.send({ id: "nickname", data: { [socket.id]: nickname } });
   }
 
-  function handlePeerData({ data }) {
+  function handlePeerData({ data, peer }) {
+    if (data.id === "sync") {
+      if (mapSource) {
+        peer.send({ id: "map", data: mapDataRef.current });
+      }
+      if (mapTokens) {
+        peer.send({ id: "tokenEdit", data: mapTokens });
+      }
+    }
     if (data.id === "map") {
       const blob = new Blob([data.data.file]);
       mapDataRef.current = { ...data.data, file: blob };