Patch 1

Freesia-Backend/src/main/java/meow/kikir/freesia/backend/tracker/TrackerProcessor.java

@@ -47,7 +47,6 @@ private void playerTrackedPlayer(@NotNull Player beSeen, @NotNull Player seeing)
             return;
         }
 
-        FreesiaBackend.INSTANCE.getSLF4JLogger().info("Player {} is tracking player {}", seeing.getName(), beSeen.getName());
         this.notifyTrackerUpdate(seeing.getUniqueId(), beSeen.getUniqueId());
     }
 

Freesia-Velocity/build.gradle.kts

@@ -6,6 +6,7 @@ dependencies {
     implementation("com.electronwill.night-config:toml:3.6.6")
     implementation("org.geysermc.mcprotocollib:protocol:1.21-SNAPSHOT")
     implementation(project(":Freesia-Common"))
+    implementation("ca.spottedleaf:concurrentutil:0.0.3")
     annotationProcessor("com.velocitypowered:velocity-api:3.3.0-SNAPSHOT")
 }
 

Freesia-Velocity/src/main/java/meow/kikir/freesia/velocity/Freesia.java

@@ -12,6 +12,7 @@
 import com.velocitypowered.api.event.connection.DisconnectEvent;
 import com.velocitypowered.api.event.connection.PluginMessageEvent;
 import com.velocitypowered.api.event.player.ServerConnectedEvent;
+import com.velocitypowered.api.event.player.ServerPostConnectEvent;
 import com.velocitypowered.api.event.player.ServerPreConnectEvent;
 import com.velocitypowered.api.event.proxy.ProxyInitializeEvent;
 import com.velocitypowered.api.plugin.Dependency;
@@ -181,4 +182,13 @@ public void onPacketSend(@NotNull PacketSendEvent event) {
             mapperManager.updateRealPlayerEntityId(target, playerSpawnPacket.getEntityId());
         }
     }
+
+    // We need to push off the packet process of worker because the player's login packet might still not reached to the client when we create the mapper session
+    @Subscribe
+    public void onServerPostConnect(@NotNull ServerPostConnectEvent postConnectEvent) {
+        final Player target = postConnectEvent.getPlayer();
+
+        // Retire callbacks of worker ysm packet processing
+        mapperManager.onBackendReady(target);
+    }
 }

Freesia-Velocity/src/main/java/meow/kikir/freesia/velocity/network/ysm/DefaultYsmPacketProxyImpl.java

@@ -20,12 +20,15 @@
 
 import java.util.Optional;
 import java.util.UUID;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 public class DefaultYsmPacketProxyImpl implements YsmPacketProxy{
     private final Player player;
     private final NbtRemapper nbtRemapper = new StandardNbtRemapperImpl();
 
     private volatile NBTCompound lastYsmEntityStatus = null;
+    private final Lock entityStatusWriteLock = new ReentrantLock(true); // We need to keep its order
 
     private volatile int playerEntityId = -1;
     private volatile int workerPlayerEntityId = -1;
@@ -80,11 +83,13 @@ private boolean isEntityStateOfSelf(int entityId){
 
     @Override
     public void sendEntityStateTo(@NotNull Player target){
-        final int currentEntityId = this.playerEntityId; // Get current entity id on the server of the player
+        this.sendEntityStateToInternal(target, this.lastYsmEntityStatus);
+    }
 
-        final NBTCompound lastEntityStatusTemp = this.lastYsmEntityStatus; // Copy the value instead of the reference
+    private void sendEntityStateToInternal(Player target, NBTCompound entityStatus) {
+        final int currentEntityId = this.playerEntityId; // Get current entity id on the server of the player
 
-        if (lastEntityStatusTemp == null || currentEntityId == -1) { // If no data got or player is not in the backend server currently
+        if (entityStatus == null || currentEntityId == -1) { // If no data got or player is not in the backend server currently
             return;
         }
 
@@ -102,7 +107,7 @@ public void sendEntityStateTo(@NotNull Player target){
 
             wrappedPacketData.writeByte(4);
             wrappedPacketData.writeVarInt(currentEntityId);
-            wrappedPacketData.writeBytes(this.nbtRemapper.shouldRemap(targetProtocolVer) ? this.nbtRemapper.remapToMasterVer(lastEntityStatusTemp) : this.nbtRemapper.remapToWorkerVer(lastEntityStatusTemp)); // Remap nbt if needed
+            wrappedPacketData.writeBytes(this.nbtRemapper.shouldRemap(targetProtocolVer) ? this.nbtRemapper.remapToMasterVer(entityStatus) : this.nbtRemapper.remapToWorkerVer(entityStatus)); // Remap nbt if needed
 
             this.sendPluginMessageTo(target, YsmMapperPayloadManager.YSM_CHANNEL_KEY_VELOCITY, wrappedPacketData);
         } catch (Exception e) {
@@ -112,12 +117,24 @@ public void sendEntityStateTo(@NotNull Player target){
 
     @Override
     public void setEntityDataRaw(NBTCompound data) {
-        this.lastYsmEntityStatus = data;
+        this.entityStatusWriteLock.lock();
+        try {
+            this.lastYsmEntityStatus = data;
+        }finally {
+            this.entityStatusWriteLock.unlock();
+        }
     }
 
     @Override
     public void refreshToOthers() {
-        this.sendEntityStateTo(this.player); // Sync to self
+        final NBTCompound entityStatusCopy = this.lastYsmEntityStatus; // Copy value
+
+        // If the player does not have any data
+        if (entityStatusCopy == null) {
+            return;
+        }
+
+        this.sendEntityStateToInternal(this.player, entityStatusCopy); // Sync to self
 
         Freesia.tracker.getCanSee(this.player.getUniqueId()).whenComplete((beingWatched, exception) -> { // Async tracker check request to backend server
             // Exception handling
@@ -137,7 +154,7 @@ public void refreshToOthers() {
                             continue;
                         }
 
-                        this.sendEntityStateTo(target); // Sync to target
+                        this.sendEntityStateToInternal(target, entityStatusCopy); // Sync to target
                     }
                 }
             }
@@ -165,7 +182,12 @@ public ProxyComputeResult processS2C(Key key, ByteBuf copiedPacketData) {
                 // We process this actions async
                 // TODO : Is here any race condition ?
                 Freesia.PROXY_SERVER.getEventManager().fire(new PlayerEntityStateChangeEvent(this.player,workerEntityId, this.nbtRemapper.readBound(mcBuffer))).thenAccept(result -> {
-                    this.lastYsmEntityStatus = result.getEntityState(); // Read using the protocol version matched for the worker
+                    this.entityStatusWriteLock.lock();
+                    try {
+                        this.lastYsmEntityStatus = result.getEntityState(); // Read using the protocol version matched for the worker
+                    }finally {
+                        this.entityStatusWriteLock.unlock();
+                    }
 
                     this.refreshToOthers();
                 });

Freesia-Velocity/src/main/java/meow/kikir/freesia/velocity/network/ysm/MapperSessionProcessor.java

@@ -1,10 +1,12 @@
 package meow.kikir.freesia.velocity.network.ysm;
 
+import ca.spottedleaf.concurrentutil.collection.MultiThreadedQueue;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import meow.kikir.freesia.velocity.Freesia;
+import meow.kikir.freesia.velocity.utils.PendingPacket;
 import net.kyori.adventure.key.Key;
 import org.geysermc.mcprotocollib.network.Session;
 import org.geysermc.mcprotocollib.network.event.session.*;
@@ -22,6 +24,7 @@ public class MapperSessionProcessor implements SessionListener {
     private final Player bindPlayer;
     private final YsmPacketProxy packetProxy;
     private final YsmMapperPayloadManager mapperPayloadManager;
+    private final MultiThreadedQueue<PendingPacket> pendingYsmPacketsInbound = new MultiThreadedQueue<>();
     private volatile Session session;
     private volatile boolean kickMasterWhenDisconnect = true;
 
@@ -66,32 +69,37 @@ public Player getBindPlayer() {
         return this.bindPlayer;
     }
 
+    public void onBackendReady() {
+        // Process incoming packets that we had not ready to process before
+        PendingPacket pendingYsmPacket;
+        while ((pendingYsmPacket = this.pendingYsmPacketsInbound.pollOrBlockAdds()) != null) { // Destroy(block add operations) the queue
+            this.processInComingYsmPacket(pendingYsmPacket.channel(), pendingYsmPacket.data());
+        }
+    }
+
     @Override
     public void packetReceived(Session session, Packet packet) {
         if (packet instanceof ClientboundLoginPacket loginPacket) {
+            // Notify entity update to notify the tracker update of the player
             Freesia.mapperManager.updateWorkerPlayerEntityId(this.bindPlayer, loginPacket.getEntityId());
+            // Worker connection callbacks, but we are not using it currently
+            // Considering to remove it in the future
             Freesia.mapperManager.onProxyLoggedin(this.bindPlayer, this, ((TcpClientSession) session));
         }
 
         if (packet instanceof ClientboundCustomPayloadPacket payloadPacket) {
             final Key channelKey = payloadPacket.getChannel();
             final byte[] packetData = payloadPacket.getData();
 
+            // If the packet is of ysm
             if (channelKey.toString().equals(YsmMapperPayloadManager.YSM_CHANNEL_KEY_ADVENTURE.toString())) {
-                final ProxyComputeResult result = this.packetProxy.processS2C(channelKey, Unpooled.wrappedBuffer(packetData));
-
-                switch (result.result()) {
-                    case MODIFY -> {
-                        final ByteBuf finalData = result.data();
-
-                        finalData.resetReaderIndex();
-
-                        this.packetProxy.sendPluginMessageToOwner(MinecraftChannelIdentifier.create(channelKey.namespace(), channelKey.value()), finalData);
-                    }
-
-                    case PASS ->
-                            this.packetProxy.sendPluginMessageToOwner(MinecraftChannelIdentifier.create(channelKey.namespace(), channelKey.value()), packetData);
+                // Check if we are not ready for the backend side yet(We will block the add operations once the backend is ready for the player)
+                final PendingPacket pendingPacket = new PendingPacket(channelKey, packetData);
+                if (!this.pendingYsmPacketsInbound.offer(pendingPacket)) {
+                    // Add is blocked, we'll process it directly
+                    this.processInComingYsmPacket(channelKey, packetData);
                 }
+                // Otherwise, we push it into the callback queue
             }
         }
 
@@ -101,6 +109,23 @@ public void packetReceived(Session session, Packet packet) {
         }
     }
 
+    private void processInComingYsmPacket(Key channelKey, byte[] packetData) {
+        final ProxyComputeResult result = this.packetProxy.processS2C(channelKey, Unpooled.wrappedBuffer(packetData));
+
+        switch (result.result()) {
+            case MODIFY -> {
+                final ByteBuf finalData = result.data();
+
+                finalData.resetReaderIndex();
+
+                this.packetProxy.sendPluginMessageToOwner(MinecraftChannelIdentifier.create(channelKey.namespace(), channelKey.value()), finalData);
+            }
+
+            case PASS ->
+                    this.packetProxy.sendPluginMessageToOwner(MinecraftChannelIdentifier.create(channelKey.namespace(), channelKey.value()), packetData);
+        }
+    }
+
     @Override
     public void packetSending(PacketSendingEvent event) {
 

Freesia-Velocity/src/main/java/meow/kikir/freesia/velocity/network/ysm/VirtualYsmPacketProxyImpl.java

@@ -48,6 +48,13 @@ public void setEntityDataRaw(NBTCompound data) {
 
     @Override
     public void refreshToOthers() {
+        final NBTCompound entityStatus = this.lastYsmEntityStatus; // Copy the value
+
+        // If the entity dose not have any data
+        if (entityStatus == null) {
+            return;
+        }
+
         Freesia.tracker.getCanSee(this.virtualPlayerUUID).whenComplete((beingWatched, exception) -> { // Async tracker check request to backend server
             if (beingWatched != null) { // Actually there is impossible to be null
                 for (UUID targetUUID : beingWatched) {
@@ -60,7 +67,7 @@ public void refreshToOthers() {
                             continue;
                         }
 
-                        this.sendEntityStateTo(target); // Sync to target
+                        this.sendEntityStateToInternal(target, entityStatus); // Sync to target
                     }
                 }
             }
@@ -101,11 +108,13 @@ public int getPlayerWorkerEntityId() {
 
     @Override
     public void sendEntityStateTo(@NotNull Player target) {
-        final int currentEntityId = this.playerEntityId; // Get current entity id on the server of the player
+        this.sendEntityStateToInternal(target, this.lastYsmEntityStatus);
+    }
 
-        final NBTCompound lastEntityStatusTemp = this.lastYsmEntityStatus; // Copy the value instead of the reference
+    private void sendEntityStateToInternal(Player target, NBTCompound entityStatus) {
+        final int currentEntityId = this.playerEntityId; // Get current entity id on the server of the player
 
-        if (lastEntityStatusTemp == null || currentEntityId == -1) { // If no data got or player is not in the backend server currently
+        if (entityStatus == null || currentEntityId == -1) { // If no data got or player is not in the backend server currently
             return;
         }
 
@@ -123,7 +132,7 @@ public void sendEntityStateTo(@NotNull Player target) {
 
             wrappedPacketData.writeByte(4);
             wrappedPacketData.writeVarInt(currentEntityId);
-            wrappedPacketData.writeBytes(this.nbtRemapper.shouldRemap(targetProtocolVer) ? this.nbtRemapper.remapToMasterVer(lastEntityStatusTemp) : this.nbtRemapper.remapToWorkerVer(lastEntityStatusTemp)); // Remap nbt if needed
+            wrappedPacketData.writeBytes(this.nbtRemapper.shouldRemap(targetProtocolVer) ? this.nbtRemapper.remapToMasterVer(entityStatus) : this.nbtRemapper.remapToWorkerVer(entityStatus)); // Remap nbt if needed
 
             this.sendPluginMessageTo(target, YsmMapperPayloadManager.YSM_CHANNEL_KEY_VELOCITY, wrappedPacketData);
         } catch (Exception e) {

Freesia-Velocity/src/main/java/meow/kikir/freesia/velocity/network/ysm/YsmMapperPayloadManager.java

@@ -284,6 +284,17 @@ public void onPluginMessageIn(@NotNull Player player, @NotNull MinecraftChannelI
         mapperSession.processPlayerPluginMessage(packetData);
     }
 
+    public void onBackendReady(Player player) {
+        final MapperSessionProcessor mapperSession = this.mapperSessions.get(player);
+
+        if (mapperSession == null) {
+            // Shouldn't be happened
+            throw new IllegalStateException("???");
+        }
+
+        mapperSession.onBackendReady();
+    }
+
     public void createMapperSession(@NotNull Player player, @NotNull InetSocketAddress backend) {
         final TcpClientSession mapperSession = new TcpClientSession(
                 backend.getHostName(),

Freesia-Velocity/src/main/java/meow/kikir/freesia/velocity/utils/PendingPacket.java

@@ -0,0 +1,9 @@
+package meow.kikir.freesia.velocity.utils;
+
+import net.kyori.adventure.key.Key;
+
+public record PendingPacket(
+        Key channel,
+        byte[] data
+) {
+}