Fix premature player kicks on shutdown

When the server is stopping, the default execution handler method will throw a
RejectedExecutionException in order to prevent further execution, this causes
us to lose the actual kick reason. To mitigate this, we'll use a seperate marked
class in order to gracefully ignore these.

paper-server/patches/sources/net/minecraft/network/Connection.java.patch

@@ -108,7 +108,7 @@
      }
  
      protected void channelRead0(ChannelHandlerContext channelhandlercontext, Packet<?> packet) {
-@@ -185,6 +231,55 @@
+@@ -185,11 +231,61 @@
              if (packetlistener == null) {
                  throw new IllegalStateException("Received a packet before the packet listener was initialized");
              } else {
@@ -164,7 +164,13 @@
                  if (packetlistener.shouldHandleMessage(packet)) {
                      try {
                          Connection.genericsFtw(packet, packetlistener);
-@@ -205,7 +300,7 @@
+                     } catch (RunningOnDifferentThreadException cancelledpackethandleexception) {
+                         ;
++                    } catch (io.papermc.paper.util.ServerStopRejectedExecutionException ignored) { // Paper - do not prematurely disconnect players on stop
+                     } catch (RejectedExecutionException rejectedexecutionexception) {
+                         this.disconnect((Component) Component.translatable("multiplayer.disconnect.server_shutdown"));
+                     } catch (ClassCastException classcastexception) {
+@@ -205,7 +301,7 @@
      }
  
      private static <T extends PacketListener> void genericsFtw(Packet<T> packet, PacketListener listener) {
@@ -173,7 +179,7 @@
      }
  
      private void validateListener(ProtocolInfo<?> state, PacketListener listener) {
-@@ -418,12 +513,26 @@
+@@ -418,12 +514,26 @@
          }
      }
  
@@ -200,7 +206,7 @@
          }
  
          if (!this.isConnected() && !this.disconnectionHandled) {
-@@ -431,7 +540,7 @@
+@@ -431,7 +541,7 @@
          }
  
          if (this.channel != null) {
@@ -209,7 +215,7 @@
          }
  
          if (this.tickCount++ % 20 == 0) {
-@@ -464,12 +573,15 @@
+@@ -464,12 +574,15 @@
      }
  
      public void disconnect(DisconnectionDetails disconnectionInfo) {
@@ -226,7 +232,7 @@
              this.disconnectionDetails = disconnectionInfo;
          }
  
-@@ -537,7 +649,7 @@
+@@ -537,7 +650,7 @@
      }
  
      public void configurePacketHandler(ChannelPipeline pipeline) {
@@ -235,7 +241,7 @@
              public void write(ChannelHandlerContext channelhandlercontext, Object object, ChannelPromise channelpromise) throws Exception {
                  super.write(channelhandlercontext, object, channelpromise);
              }
-@@ -633,6 +745,7 @@
+@@ -633,6 +746,7 @@
              } else {
                  this.channel.pipeline().addAfter("prepender", "compress", new CompressionEncoder(compressionThreshold));
              }
@@ -243,7 +249,7 @@
          } else {
              if (this.channel.pipeline().get("decompress") instanceof CompressionDecoder) {
                  this.channel.pipeline().remove("decompress");
-@@ -641,6 +754,7 @@
+@@ -641,6 +755,7 @@
              if (this.channel.pipeline().get("compress") instanceof CompressionEncoder) {
                  this.channel.pipeline().remove("compress");
              }
@@ -251,7 +257,7 @@
          }
  
      }
-@@ -661,6 +775,27 @@
+@@ -661,6 +776,27 @@
  
                      packetlistener1.onDisconnect(disconnectiondetails);
                  }

paper-server/patches/sources/net/minecraft/server/MinecraftServer.java.patch

@@ -1232,6 +1232,15 @@
      }
  
      public boolean isReady() {
+@@ -1593,7 +2127,7 @@
+     @Override
+     public void executeIfPossible(Runnable runnable) {
+         if (this.isStopped()) {
+-            throw new RejectedExecutionException("Server already shutting down");
++            throw new io.papermc.paper.util.ServerStopRejectedExecutionException("Server already shutting down"); // Paper - do not prematurely disconnect players on stop
+         } else {
+             super.executeIfPossible(runnable);
+         }
 @@ -1632,13 +2166,19 @@
          return this.functionManager;
      }
@@ -1312,22 +1321,19 @@
  
                      try {
                          arraylist = Lists.newArrayList(NativeModuleLister.listModules());
-@@ -2105,9 +2650,24 @@
-         if (bufferedwriter != null) {
-             bufferedwriter.close();
-         }
-+
-+    }
-+
+@@ -2108,6 +2653,21 @@
+ 
+     }
+ 
 +    // CraftBukkit start
 +    public boolean isDebugging() {
 +        return false;
 +    }
- 
++
 +    public static MinecraftServer getServer() {
 +        return SERVER; // Paper
-     }
- 
++    }
++
 +    @Deprecated
 +    public static RegistryAccess getDefaultRegistryAccess() {
 +        return CraftRegistry.getMinecraftRegistry();
@@ -1366,11 +1372,13 @@
      }
  
      public boolean logIPs() {
-@@ -2379,4 +2945,30 @@
-     public static record ServerResourcePackInfo(UUID id, String url, String hash, boolean isRequired, @Nullable Component prompt) {
- 
+@@ -2377,6 +2943,32 @@
      }
+ 
+     public static record ServerResourcePackInfo(UUID id, String url, String hash, boolean isRequired, @Nullable Component prompt) {
 +
++    }
+ 
 +    // Paper start - Add tick times API and /mspt command
 +    public static class TickTimes {
 +        private final long[] times;
@@ -1394,6 +1402,6 @@
 +            }
 +            return ((double) total / (double) times.length) * 1.0E-6D;
 +        }
-+    }
+     }
 +    // Paper end - Add tick times API and /mspt command
  }

paper-server/src/main/java/io/papermc/paper/util/ServerStopRejectedExecutionException.java

@@ -0,0 +1,20 @@
+package io.papermc.paper.util;
+
+import java.util.concurrent.RejectedExecutionException;
+
+public class ServerStopRejectedExecutionException extends RejectedExecutionException {
+    public ServerStopRejectedExecutionException() {
+    }
+
+    public ServerStopRejectedExecutionException(final String message) {
+        super(message);
+    }
+
+    public ServerStopRejectedExecutionException(final String message, final Throwable cause) {
+        super(message, cause);
+    }
+
+    public ServerStopRejectedExecutionException(final Throwable cause) {
+        super(cause);
+    }
+}