Folia Hide/Show Player Race Condition Fix

core/src/main/java/org/geysermc/floodgate/command/UnlinkAccountCommand.java

@@ -32,14 +32,14 @@
 import lombok.NoArgsConstructor;
 import org.geysermc.floodgate.api.FloodgateApi;
 import org.geysermc.floodgate.api.link.PlayerLink;
+import org.geysermc.floodgate.command.util.Permission;
 import org.geysermc.floodgate.config.FloodgateConfig;
 import org.geysermc.floodgate.link.GlobalPlayerLinking;
 import org.geysermc.floodgate.platform.command.FloodgateCommand;
 import org.geysermc.floodgate.platform.command.TranslatableMessage;
 import org.geysermc.floodgate.player.UserAudience;
 import org.geysermc.floodgate.player.UserAudience.PlayerAudience;
 import org.geysermc.floodgate.util.Constants;
-import org.geysermc.floodgate.command.util.Permission;
 import org.incendo.cloud.Command;
 import org.incendo.cloud.CommandManager;
 import org.incendo.cloud.context.CommandContext;

core/src/main/java/org/geysermc/floodgate/command/WhitelistCommand.java

@@ -40,7 +40,6 @@
 import org.geysermc.floodgate.platform.command.CommandUtil;
 import org.geysermc.floodgate.platform.command.FloodgateCommand;
 import org.geysermc.floodgate.platform.command.TranslatableMessage;
-import org.geysermc.floodgate.platform.util.PlayerType;
 import org.geysermc.floodgate.player.UserAudience;
 import org.geysermc.floodgate.player.audience.PlayerAudienceArgument;
 import org.geysermc.floodgate.player.audience.ProfileAudience;

core/src/main/java/org/geysermc/floodgate/link/GlobalPlayerLinking.java

@@ -32,6 +32,7 @@
 import com.google.inject.Inject;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
 import lombok.Getter;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.geysermc.floodgate.api.link.LinkRequestResult;
@@ -95,28 +96,39 @@ public CompletableFuture<LinkedPlayer> getLinkedPlayer(@NonNull UUID bedrockId)
 
     @NonNull
     private CompletableFuture<LinkedPlayer> getLinkedPlayer0(@NonNull UUID bedrockId) {
+        ExecutorService executor = getExecutorService();
+        if (executor.isShutdown() || executor.isTerminated()) {
+            return CompletableFuture.completedFuture(null);
+        }
+
         return CompletableFuture.supplyAsync(
                 () -> {
                     DefaultHttpResponse response =
                             httpClient.get(GET_BEDROCK_LINK + bedrockId.getLeastSignificantBits());
 
+                    JsonObject data = response.getResponse();
+
                     // either the global api is down or it failed to return link
-                    if (!response.isCodeOk()) {
-                        if (response.getResponse() != null) {
+                    if (!response.isCodeOk() || data == null) {
+                        if (data != null && data.has("message")) {
                             getLogger().error(
                                     "Failed to request link for {}: {}",
                                     bedrockId.getLeastSignificantBits(),
-                                    response.getResponse().get("message").getAsString()
+                                    data.get("message").getAsString()
+                            );
+                        } else {
+                            getLogger().error(
+                                    "Failed to request link for {}: empty or invalid response (HTTP {})",
+                                    bedrockId.getLeastSignificantBits(),
+                                    response.getHttpCode()
                             );
                         }
                         return null;
                     }
 
-                    JsonObject data = response.getResponse();
-
                     JsonElement javaName = data.get("java_name");
                     // javaName will be null when the player isn't linked
-                    if (javaName == null) {
+                    if (javaName == null || javaName.isJsonNull()) {
                         return null;
                     }
 
@@ -125,7 +137,7 @@ private CompletableFuture<LinkedPlayer> getLinkedPlayer0(@NonNull UUID bedrockId
                             UUID.fromString(data.get("java_id").getAsString()),
                             Utils.getJavaUuid(data.get("bedrock_id").getAsLong()));
                 },
-                getExecutorService());
+                executor);
     }
 
     @Override
@@ -145,23 +157,39 @@ public CompletableFuture<Boolean> isLinkedPlayer(@NonNull UUID bedrockId) {
 
     @NonNull
     private CompletableFuture<Boolean> isLinkedPlayer0(@NonNull UUID bedrockId) {
+        ExecutorService executor = getExecutorService();
+        if (executor.isShutdown() || executor.isTerminated()) {
+            return CompletableFuture.completedFuture(false);
+        }
+
         return CompletableFuture.supplyAsync(
                 () -> {
                     DefaultHttpResponse response =
                             httpClient.get(GET_BEDROCK_LINK + bedrockId.getLeastSignificantBits());
 
-                    if (!response.isCodeOk()) {
-                        getLogger().error(
-                                "Failed to request link for {}: {}",
-                                bedrockId.getLeastSignificantBits(),
-                                response.getResponse().get("message").getAsString());
+                    JsonObject data = response.getResponse();
+
+                    if (!response.isCodeOk() || data == null) {
+                        if (data != null && data.has("message")) {
+                            getLogger().error(
+                                    "Failed to request link for {}: {}",
+                                    bedrockId.getLeastSignificantBits(),
+                                    data.get("message").getAsString()
+                            );
+                        } else {
+                            getLogger().error(
+                                    "Failed to request link for {}: empty or invalid response (HTTP {})",
+                                    bedrockId.getLeastSignificantBits(),
+                                    response.getHttpCode()
+                            );
+                        }
                         return false;
                     }
 
                     // no link if data is empty, otherwise the player is linked
-                    return response.getResponse().entrySet().size() != 0;
+                    return data.entrySet().size() != 0;
                 },
-                getExecutorService());
+                executor);
     }
 
     // player linking and unlinking now goes through the global player linking server.

core/src/main/java/org/geysermc/floodgate/util/HttpClient.java

@@ -26,6 +26,7 @@
 package org.geysermc.floodgate.util;
 
 import com.google.gson.Gson;
+import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
@@ -135,12 +136,20 @@ private DefaultHttpResponse readDefaultResponse(HttpURLConnection connection) {
             return new DefaultHttpResponse(-1, null);
         }
 
+        int responseCode = -1;
         try {
-            int responseCode = connection.getResponseCode();
-            JsonObject response = gson.fromJson(streamReader, JsonObject.class);
+            responseCode = connection.getResponseCode();
+
+            JsonElement element = gson.fromJson(streamReader, JsonElement.class);
+
+            JsonObject response = null;
+            if (element != null && element.isJsonObject()) {
+                response = element.getAsJsonObject();
+            }
+
             return new DefaultHttpResponse(responseCode, response);
-        } catch (Exception exception) {
-            throw new RuntimeException("Failed to read response", exception);
+        } catch (Exception ignored) {
+            return new DefaultHttpResponse(responseCode, null);
         } finally {
             try {
                 streamReader.close();

spigot/src/main/java/org/geysermc/floodgate/SpigotPlugin.java

@@ -27,7 +27,6 @@
 
 import com.google.inject.Guice;
 import com.google.inject.Injector;
-import org.bukkit.Bukkit;
 import org.bukkit.plugin.java.JavaPlugin;
 import org.geysermc.floodgate.api.handshake.HandshakeHandlers;
 import org.geysermc.floodgate.api.logger.FloodgateLogger;

spigot/src/main/java/org/geysermc/floodgate/util/SpigotCommandUtil.java

@@ -27,7 +27,6 @@
 
 import java.util.Collection;
 import java.util.UUID;
-import org.bukkit.OfflinePlayer;
 import org.bukkit.Server;
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;

spigot/src/main/java/org/geysermc/floodgate/util/SpigotVersionSpecificMethods.java

@@ -35,6 +35,7 @@
 import java.util.Map;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
+import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 import org.bukkit.plugin.Plugin;
 import org.geysermc.floodgate.SpigotPlugin;
@@ -120,7 +121,7 @@ public String getLocale(Player player) {
     }
 
     public void hideAndShowPlayer(Player on, Player target) {
-        // In Folia we don't have to schedule this as there is no concept of a single main thread.
+        // In Folia, we don't have to schedule this as there is no concept of a single main thread.
         // Instead, we have to schedule the task per player.
         if (ClassNames.IS_FOLIA) {
             on.getScheduler().execute(plugin, () -> hideAndShowPlayer0(on, target), null, 0);
@@ -168,6 +169,9 @@ public void schedule(Runnable runnable, long delay) {
 
     @SuppressWarnings("deprecation")
     private void hideAndShowPlayer0(Player source, Player target) {
+        if (!Bukkit.isOwnedByCurrentRegion(source) || !Bukkit.isOwnedByCurrentRegion(target)) {
+            return;
+        }
         if (NEW_VISIBILITY) {
             source.hidePlayer(plugin, target);
             source.showPlayer(plugin, target);
@@ -182,7 +186,7 @@ public void maybeSchedule(Runnable runnable) {
     }
 
     public void maybeSchedule(Runnable runnable, boolean globalContext) {
-        // In Folia we don't usually have to schedule this as there is no concept of a single main thread.
+        // In Folia, we don't usually have to schedule this as there is no concept of a single main thread.
         // Instead, we have to schedule the task per player.
         // However, in some cases we may want to access the global region for a global context.
         if (ClassNames.IS_FOLIA) {

spigot/src/main/java/org/geysermc/floodgate/util/WhitelistUtils.java

@@ -29,7 +29,6 @@
 import java.util.UUID;
 import org.bukkit.Bukkit;
 import org.bukkit.OfflinePlayer;
-import org.bukkit.Server;
 
 @SuppressWarnings("ConstantConditions")
 public final class WhitelistUtils {