Fix cached packets being outdated

src/main/java/net/minestom/server/network/packet/server/play/ChunkDataPacket.java

@@ -16,6 +16,7 @@ import net.minestom.server.utils.Utils;
 import net.minestom.server.utils.binary.BinaryWriter;
 import net.minestom.server.utils.cache.CacheablePacket;
 import net.minestom.server.utils.cache.TemporaryCache;
+import net.minestom.server.utils.cache.TimedBuffer;
 import net.minestom.server.utils.chunk.ChunkUtils;
 import net.minestom.server.world.biomes.Biome;
 import org.jetbrains.annotations.NotNull;
@@ -27,7 +28,7 @@ import java.util.UUID;
 public class ChunkDataPacket implements ServerPacket, CacheablePacket {
 
     private static final BlockManager BLOCK_MANAGER = MinecraftServer.getBlockManager();
-    private static final TemporaryCache<ByteBuf> CACHE = new TemporaryCache<>(10000L);
+    private static final TemporaryCache<TimedBuffer> CACHE = new TemporaryCache<>(10000L);
 
     public boolean fullChunk;
     public Biome[] biomes;
@@ -46,12 +47,12 @@ public class ChunkDataPacket implements ServerPacket, CacheablePacket {
     private static final int MAX_BUFFER_SIZE = (Short.BYTES + Byte.BYTES + 5 * Byte.BYTES + (4096 * MAX_BITS_PER_ENTRY / Long.SIZE * Long.BYTES)) * CHUNK_SECTION_COUNT + 256 * Integer.BYTES;
 
     // Cacheable data
-    private UUID identifier;
+    private final UUID identifier;
-    private long lastUpdate;
+    private final long timestamp;
 
-    public ChunkDataPacket(@Nullable UUID identifier, long lastUpdate) {
+    public ChunkDataPacket(@Nullable UUID identifier, long timestamp) {
         this.identifier = identifier;
-        this.lastUpdate = lastUpdate;
+        this.timestamp = timestamp;
     }
 
     @Override
@@ -139,7 +140,7 @@ public class ChunkDataPacket implements ServerPacket, CacheablePacket {
 
     @NotNull
     @Override
-    public TemporaryCache<ByteBuf> getCache() {
+    public TemporaryCache<TimedBuffer> getCache() {
         return CACHE;
     }
 
@@ -147,4 +148,9 @@ public class ChunkDataPacket implements ServerPacket, CacheablePacket {
     public UUID getIdentifier() {
         return identifier;
     }
+
+    @Override
+    public long getTimestamp() {
+        return timestamp;
+    }
 }

src/main/java/net/minestom/server/network/packet/server/play/UpdateLightPacket.java

@@ -1,11 +1,11 @@
 package net.minestom.server.network.packet.server.play;
 
-import io.netty.buffer.ByteBuf;
 import net.minestom.server.network.packet.server.ServerPacket;
 import net.minestom.server.network.packet.server.ServerPacketIdentifier;
 import net.minestom.server.utils.binary.BinaryWriter;
 import net.minestom.server.utils.cache.CacheablePacket;
 import net.minestom.server.utils.cache.TemporaryCache;
+import net.minestom.server.utils.cache.TimedBuffer;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -14,7 +14,7 @@ import java.util.UUID;
 
 public class UpdateLightPacket implements ServerPacket, CacheablePacket {
 
-    private static final TemporaryCache<ByteBuf> CACHE = new TemporaryCache<>(10000L);
+    private static final TemporaryCache<TimedBuffer> CACHE = new TemporaryCache<>(10000L);
 
     public int chunkX;
     public int chunkZ;
@@ -31,12 +31,12 @@ public class UpdateLightPacket implements ServerPacket, CacheablePacket {
     public List<byte[]> blockLight;
 
     // Cacheable data
-    private UUID identifier;
+    private final UUID identifier;
-    private long lastUpdate;
+    private final long timestamp;
 
-    public UpdateLightPacket(@Nullable UUID identifier, long lastUpdate) {
+    public UpdateLightPacket(@Nullable UUID identifier, long timestamp) {
         this.identifier = identifier;
-        this.lastUpdate = lastUpdate;
+        this.timestamp = timestamp;
     }
 
     @Override
@@ -72,7 +72,7 @@ public class UpdateLightPacket implements ServerPacket, CacheablePacket {
 
     @NotNull
     @Override
-    public TemporaryCache<ByteBuf> getCache() {
+    public TemporaryCache<TimedBuffer> getCache() {
         return CACHE;
     }
 
@@ -80,4 +80,9 @@ public class UpdateLightPacket implements ServerPacket, CacheablePacket {
     public UUID getIdentifier() {
         return identifier;
     }
+
+    @Override
+    public long getTimestamp() {
+        return timestamp;
+    }
 }

src/main/java/net/minestom/server/network/player/NettyPlayerConnection.java

@@ -18,6 +18,7 @@ import net.minestom.server.network.packet.server.login.SetCompressionPacket;
 import net.minestom.server.utils.PacketUtils;
 import net.minestom.server.utils.cache.CacheablePacket;
 import net.minestom.server.utils.cache.TemporaryCache;
+import net.minestom.server.utils.cache.TimedBuffer;
 import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -128,15 +129,25 @@ public class NettyPlayerConnection extends PlayerConnection {
                         // This packet explicitly asks to do not retrieve the cache
                         write(serverPacket);
                     } else {
+                        final long time = cacheablePacket.getTimestamp();
                         // Try to retrieve the cached buffer
-                        TemporaryCache<ByteBuf> temporaryCache = cacheablePacket.getCache();
+                        TemporaryCache<TimedBuffer> temporaryCache = cacheablePacket.getCache();
-                        ByteBuf buffer = temporaryCache.retrieve(identifier);
+                        TimedBuffer timedBuffer = temporaryCache.retrieve(identifier);
-                        if (buffer == null) {
+                        boolean shouldUpdate = false;
+                        if (timedBuffer == null) {
                             // Buffer not found, create and cache it
-                            buffer = PacketUtils.createFramedPacket(serverPacket, false);
+                            final ByteBuf buffer = PacketUtils.createFramedPacket(serverPacket, false);
-                            temporaryCache.cache(identifier, buffer);
+                            timedBuffer = new TimedBuffer(buffer, time);
+                            shouldUpdate = true;
+                        } else if (time > timedBuffer.getTimestamp()) { // Verify if `serverPacket` is more up-to-date
+                            shouldUpdate = true;
                         }
-                        FramedPacket framedPacket = new FramedPacket(buffer);
+
+                        if (shouldUpdate) {
+                            temporaryCache.cache(identifier, timedBuffer);
+                        }
+
+                        FramedPacket framedPacket = new FramedPacket(timedBuffer.getBuffer());
                         write(framedPacket);
                     }
 

src/main/java/net/minestom/server/utils/cache/CacheablePacket.java

@@ -1,6 +1,5 @@
 package net.minestom.server.utils.cache;
 
-import io.netty.buffer.ByteBuf;
 import net.minestom.server.network.packet.server.ServerPacket;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -23,7 +22,7 @@ public interface CacheablePacket {
      * @return the temporary packet cache
      */
     @NotNull
-    TemporaryCache<ByteBuf> getCache();
+    TemporaryCache<TimedBuffer> getCache();
 
     /**
      * Gets the identifier of this packet.
@@ -35,4 +34,11 @@ public interface CacheablePacket {
     @Nullable
     UUID getIdentifier();
 
+    /**
+     * Gets the last time this packet changed.
+     *
+     * @return the last packet update time in milliseconds
+     */
+    long getTimestamp();
+
 }

src/main/java/net/minestom/server/utils/cache/TimedBuffer.java

@@ -0,0 +1,28 @@
+package net.minestom.server.utils.cache;
+
+import io.netty.buffer.ByteBuf;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Object containing a {@link ByteBuf buffer} and its timestamp.
+ * Used for packet-caching to use the most recent.
+ */
+public class TimedBuffer {
+
+    private final ByteBuf buffer;
+    private final long timestamp;
+
+    public TimedBuffer(@NotNull ByteBuf buffer, long timestamp) {
+        this.buffer = buffer;
+        this.timestamp = timestamp;
+    }
+
+    @NotNull
+    public ByteBuf getBuffer() {
+        return buffer;
+    }
+
+    public long getTimestamp() {
+        return timestamp;
+    }
+}