Give thread pools time to terminate & Save all data before shutting down

this should be configurable

src/main/java/emu/grasscutter/Grasscutter.java

@@ -1,8 +1,5 @@
 package emu.grasscutter;
 
-import static emu.grasscutter.config.Configuration.SERVER;
-import static emu.grasscutter.utils.lang.Language.translate;
-
 import ch.qos.logback.classic.*;
 import emu.grasscutter.auth.*;
 import emu.grasscutter.command.*;
@@ -21,16 +18,20 @@ import emu.grasscutter.tools.Tools;
 import emu.grasscutter.utils.*;
 import emu.grasscutter.utils.lang.Language;
 import io.netty.util.concurrent.FastThreadLocalThread;
-import java.io.*;
-import java.util.Calendar;
-import java.util.concurrent.*;
-import javax.annotation.Nullable;
 import lombok.*;
 import org.jline.reader.*;
 import org.jline.terminal.*;
 import org.reflections.Reflections;
 import org.slf4j.LoggerFactory;
 
+import javax.annotation.Nullable;
+import java.io.*;
+import java.util.Calendar;
+import java.util.concurrent.*;
+
+import static emu.grasscutter.config.Configuration.SERVER;
+import static emu.grasscutter.utils.lang.Language.translate;
+
 public final class Grasscutter {
     public static final File configFile = new File("./config.json");
     public static final Reflections reflector = new Reflections("emu.grasscutter");
@@ -181,12 +182,18 @@ public final class Grasscutter {
         // Hook into shutdown event.
         Runtime.getRuntime().addShutdownHook(new Thread(Grasscutter::onShutdown));
 
+        // Start database heartbeat.
+        Database.startSaveThread();
+
         // Open console.
         Grasscutter.startConsole();
     }
 
     /** Server shutdown event. */
     private static void onShutdown() {
+        // Save all data.
+        Database.saveAll();
+
         // Disable all plugins.
         if (pluginManager != null) pluginManager.disablePlugins();
         // Shutdown the game server.
@@ -196,14 +203,14 @@ public final class Grasscutter {
             // Wait for Grasscutter's thread pool to finish.
             var executor = Grasscutter.getThreadPool();
             executor.shutdown();
-            if (!executor.awaitTermination(5, TimeUnit.SECONDS)) {
+            if (!executor.awaitTermination(1, TimeUnit.MINUTES)) {
                 executor.shutdownNow();
             }
 
             // Wait for database operations to finish.
             var dbExecutor = DatabaseHelper.getEventExecutor();
             dbExecutor.shutdown();
-            if (!dbExecutor.awaitTermination(5, TimeUnit.SECONDS)) {
+            if (!dbExecutor.awaitTermination(2, TimeUnit.MINUTES)) {
                 dbExecutor.shutdownNow();
             }
         } catch (InterruptedException ignored) {

src/main/java/emu/grasscutter/database/Database.java

@@ -0,0 +1,85 @@
+package emu.grasscutter.database;
+
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.utils.objects.DatabaseObject;
+import org.slf4j.*;
+
+import java.util.*;
+import java.util.concurrent.*;
+
+/**
+ * Complicated manager of the MongoDB database.
+ * Handles caching, data operations, and more.
+ */
+public interface Database {
+    Logger logger = LoggerFactory.getLogger("Database");
+    List<DatabaseObject<?>> objects = new CopyOnWriteArrayList<>();
+
+    /**
+     * Queues an object to be saved.
+     *
+     * @param object The object to save.
+     */
+    static void save(DatabaseObject<?> object) {
+        if (object.saveImmediately()) {
+            object.save();
+        } else {
+            objects.add(object);
+        }
+    }
+
+    /**
+     * Performs a bulk save of all deferred objects.
+     */
+    static void saveAll() {
+        var size = objects.size();
+        Database.saveAll(objects);
+
+        logger.debug("Performed auto save on {} objects.", size);
+    }
+
+    /**
+     * Performs a bulk save of all deferred objects.
+     *
+     * @param objects The objects to save.
+     */
+    static void saveAll(List<? extends DatabaseObject<?>> objects) {
+        // Sort all objects into their respective databases.
+        var gameObjects = objects.stream()
+                .filter(DatabaseObject::isGameObject)
+                .toList();
+        var accountObjects = objects.stream()
+                .filter(o -> !o.isGameObject())
+                .toList();
+
+        // Clear the collective list.
+        objects.clear();
+
+        // Save all objects.
+        var executor = DatabaseHelper.getEventExecutor();
+        if (Grasscutter.getRunMode() != Grasscutter.ServerRunMode.DISPATCH_ONLY) {
+            executor.submit(() -> {
+                DatabaseManager.getGameDatastore().save(gameObjects);
+            });
+        }
+        if (Grasscutter.getRunMode() != Grasscutter.ServerRunMode.GAME_ONLY) {
+            executor.submit(() -> {
+                DatabaseManager.getAccountDatastore().save(accountObjects);
+            });
+        }
+    }
+
+    /**
+     * Starts the auto-save thread.
+     * Runs every 5 minutes.
+     */
+    static void startSaveThread() {
+        var timer = new Timer();
+        timer.scheduleAtFixedRate(new TimerTask() {
+            @Override
+            public void run() {
+                Database.saveAll();
+            }
+        }, 0, 1000 * 60 * 5);
+    }
+}

src/main/java/emu/grasscutter/database/DatabaseHelper.java

@@ -1,7 +1,5 @@
 package emu.grasscutter.database;
 
-import static com.mongodb.client.model.Filters.eq;
-
 import dev.morphia.query.*;
 import dev.morphia.query.experimental.filters.Filters;
 import emu.grasscutter.*;
@@ -20,24 +18,19 @@ import emu.grasscutter.game.player.Player;
 import emu.grasscutter.game.quest.GameMainQuest;
 import emu.grasscutter.game.world.SceneGroupInstance;
 import emu.grasscutter.utils.objects.Returnable;
-import io.netty.util.concurrent.FastThreadLocalThread;
+import lombok.Getter;
+
+import javax.annotation.Nullable;
 import java.util.List;
 import java.util.concurrent.*;
 import java.util.stream.Stream;
-import javax.annotation.Nullable;
+
-import lombok.Getter;
+import static com.mongodb.client.model.Filters.eq;
 
 public final class DatabaseHelper {
     @Getter
     private static final ExecutorService eventExecutor =
-            new ThreadPoolExecutor(
+        Executors.newFixedThreadPool(4);
-                    6,
-                    6,
-                    60,
-                    TimeUnit.SECONDS,
-                    new LinkedBlockingDeque<>(),
-                    FastThreadLocalThread::new,
-                    new ThreadPoolExecutor.AbortPolicy());
 
     /**
      * Saves an object on the account datastore.

src/main/java/emu/grasscutter/game/achievement/Achievements.java

@@ -12,12 +12,13 @@ import emu.grasscutter.game.props.ActionReason;
 import emu.grasscutter.net.proto.AchievementOuterClass.Achievement.Status;
 import emu.grasscutter.server.event.player.PlayerCompleteAchievementEvent;
 import emu.grasscutter.server.packet.send.*;
+import lombok.*;
+import org.bson.types.ObjectId;
+
+import javax.annotation.Nullable;
 import java.util.*;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.IntSupplier;
-import javax.annotation.Nullable;
-import lombok.*;
-import org.bson.types.ObjectId;
 
 @Entity("achievements")
 @Data
@@ -44,15 +45,30 @@ public class Achievements {
         return achievements;
     }
 
-    public static Achievements create(int uid) {
+    /**
-        var newAchievement =
+     * Creates a blank achievements object.
-                Achievements.of()
+     *
-                        .uid(uid)
+     * @return The achievements object.
+     */
+    public static Achievements blank() {
+        return Achievements.of()
                 .achievementList(init())
                 .finishedAchievementNum(0)
                 .takenGoalRewardIdList(Lists.newArrayList())
                 .build();
+    }
+
+    /**
+     * Creates and saves a blank achievements object.
+     *
+     * @param uid The UID of the player.
+     * @return The achievements object.
+     */
+    public static Achievements create(int uid) {
+        var newAchievement = blank();
+        newAchievement.setUid(uid);
         newAchievement.save();
+
         return newAchievement;
     }
 

src/main/java/emu/grasscutter/game/activity/PlayerActivityData.java

@@ -11,15 +11,17 @@ import emu.grasscutter.game.props.ActionReason;
 import emu.grasscutter.net.proto.ActivityWatcherInfoOuterClass;
 import emu.grasscutter.server.packet.send.PacketActivityUpdateWatcherNotify;
 import emu.grasscutter.utils.JsonUtils;
-import java.util.*;
+import emu.grasscutter.utils.objects.DatabaseObject;
 import lombok.*;
 import lombok.experimental.FieldDefaults;
 
+import java.util.*;
+
 @Entity("activities")
 @Data
 @FieldDefaults(level = AccessLevel.PRIVATE)
 @Builder(builderMethodName = "of")
-public class PlayerActivityData {
+public class PlayerActivityData implements DatabaseObject<PlayerActivityData> {
     @Id String id;
     int uid;
     int activityId;
@@ -34,8 +36,25 @@ public class PlayerActivityData {
         return DatabaseHelper.getPlayerActivityData(player.getUid(), activityId);
     }
 
+    /**
+     * Saves this object to the database.
+     * As of Grasscutter 1.7.1, this is by default a {@link DatabaseObject#deferSave()} call.
+     */
     public void save() {
-        DatabaseHelper.savePlayerActivityData(this);
+        this.deferSave();
+    }
+
+    /**
+     * Saves this object to the database.
+     *
+     * @param immediate If true, this will be a {@link DatabaseObject#save()} call instead of a {@link DatabaseObject#deferSave()} call.
+     */
+    public void save(boolean immediate) {
+        if (immediate) {
+            DatabaseObject.super.save();
+        } else {
+            this.save();
+        }
     }
 
     public synchronized void addWatcherProgress(int watcherId) {

src/main/java/emu/grasscutter/game/avatar/Avatar.java

@@ -1,7 +1,5 @@
 package emu.grasscutter.game.avatar;
 
-import static emu.grasscutter.config.Configuration.GAME_OPTIONS;
-
 import dev.morphia.annotations.*;
 import emu.grasscutter.GameConstants;
 import emu.grasscutter.data.GameData;
@@ -15,7 +13,6 @@ import emu.grasscutter.data.excels.avatar.AvatarSkillDepotData.InherentProudSkil
 import emu.grasscutter.data.excels.reliquary.*;
 import emu.grasscutter.data.excels.trial.TrialAvatarTemplateData;
 import emu.grasscutter.data.excels.weapon.*;
-import emu.grasscutter.database.DatabaseHelper;
 import emu.grasscutter.game.entity.*;
 import emu.grasscutter.game.inventory.*;
 import emu.grasscutter.game.player.Player;
@@ -31,15 +28,19 @@ import emu.grasscutter.net.proto.TrialAvatarGrantRecordOuterClass.TrialAvatarGra
 import emu.grasscutter.net.proto.TrialAvatarInfoOuterClass.TrialAvatarInfo;
 import emu.grasscutter.server.packet.send.*;
 import emu.grasscutter.utils.helpers.ProtoHelper;
+import emu.grasscutter.utils.objects.DatabaseObject;
 import it.unimi.dsi.fastutil.ints.*;
-import java.util.*;
-import java.util.stream.Stream;
-import javax.annotation.*;
 import lombok.*;
 import org.bson.types.ObjectId;
 
+import javax.annotation.*;
+import java.util.*;
+import java.util.stream.Stream;
+
+import static emu.grasscutter.config.Configuration.GAME_OPTIONS;
+
 @Entity(value = "avatars", useDiscriminator = false)
-public class Avatar {
+public class Avatar implements DatabaseObject<Avatar> {
     @Transient @Getter private final Int2ObjectMap<GameItem> equips;
     @Transient @Getter private final Int2FloatOpenHashMap fightProperties;
     @Transient @Getter private final Int2FloatOpenHashMap fightPropOverrides;
@@ -989,8 +990,25 @@ public class Avatar {
         return entity != null ? entity.getId() : 0;
     }
 
+    /**
+     * Saves this object to the database.
+     * As of Grasscutter 1.7.1, this is by default a {@link DatabaseObject#deferSave()} call.
+     */
     public void save() {
-        DatabaseHelper.saveAvatar(this);
+        this.deferSave();
+    }
+
+    /**
+     * Saves this object to the database.
+     *
+     * @param immediate If true, this will be a {@link DatabaseObject#save()} call instead of a {@link DatabaseObject#deferSave()} call.
+     */
+    public void save(boolean immediate) {
+        if (immediate) {
+            DatabaseObject.super.save();
+        } else {
+            this.save();
+        }
     }
 
     public AvatarInfo toProto() {

src/main/java/emu/grasscutter/game/avatar/AvatarStorage.java

@@ -60,7 +60,7 @@ public class AvatarStorage extends BasePlayerManager implements Iterable<Avatar>
         this.avatars.put(avatar.getAvatarId(), avatar);
         this.avatarsGuid.put(avatar.getGuid(), avatar);
 
-        avatar.save();
+        avatar.save(true);
 
         return true;
     }
@@ -165,7 +165,7 @@ public class AvatarStorage extends BasePlayerManager implements Iterable<Avatar>
             if ((avatar.getAvatarId() == 10000007) || (avatar.getAvatarId() == 10000005)) {
                 avatar.setSkillDepot(skillDepot);
                 avatar.setSkillDepotData(skillDepot);
-                avatar.save();
+                avatar.save(true);
             }
         }
 

src/main/java/emu/grasscutter/game/battlepass/BattlePassManager.java

@@ -14,11 +14,12 @@ import emu.grasscutter.net.proto.BattlePassRewardTakeOptionOuterClass.BattlePass
 import emu.grasscutter.net.proto.BattlePassScheduleOuterClass.BattlePassSchedule;
 import emu.grasscutter.net.proto.BattlePassUnlockStatusOuterClass.BattlePassUnlockStatus;
 import emu.grasscutter.server.packet.send.*;
+import lombok.Getter;
+import org.bson.types.ObjectId;
+
 import java.time.*;
 import java.time.temporal.TemporalAdjusters;
 import java.util.*;
-import lombok.Getter;
-import org.bson.types.ObjectId;
 
 @Entity(value = "battlepass", useDiscriminator = false)
 public class BattlePassManager extends BasePlayerDataManager {
@@ -40,7 +41,10 @@ public class BattlePassManager extends BasePlayerDataManager {
 
     public BattlePassManager(Player player) {
         super(player);
+
         this.ownerUid = player.getUid();
+        this.missions = new HashMap<>();
+        this.takenRewards = new HashMap<>();
     }
 
     public void setPlayer(Player player) {

src/main/java/emu/grasscutter/game/inventory/GameItem.java

@@ -20,13 +20,14 @@ import emu.grasscutter.net.proto.ReliquaryOuterClass.Reliquary;
 import emu.grasscutter.net.proto.SceneReliquaryInfoOuterClass.SceneReliquaryInfo;
 import emu.grasscutter.net.proto.SceneWeaponInfoOuterClass.SceneWeaponInfo;
 import emu.grasscutter.net.proto.WeaponOuterClass.Weapon;
-import emu.grasscutter.utils.objects.WeightedList;
+import emu.grasscutter.utils.objects.*;
-import java.util.*;
 import lombok.*;
 import org.bson.types.ObjectId;
 
+import java.util.*;
+
 @Entity(value = "items", useDiscriminator = false)
-public class GameItem {
+public class GameItem implements DatabaseObject<GameItem> {
     @Id private ObjectId id;
     @Indexed private int ownerId;
     @Getter @Setter private int itemId;
@@ -261,14 +262,36 @@ public class GameItem {
         }
     }
 
+    /**
+     * Saves this object to the database.
+     * As of Grasscutter 1.7.1, this is by default a {@link DatabaseObject#deferSave()} call.
+     */
     public void save() {
         if (this.count > 0 && this.ownerId > 0) {
-            DatabaseHelper.saveItem(this);
+            this.deferSave();
-        } else if (this.getObjectId() != null) {
+        } else {
             DatabaseHelper.deleteItem(this);
         }
     }
 
+    /**
+     * Saves this object to the database.
+     *
+     * @param immediate If true, this will be a {@link DatabaseObject#save()} call instead of a {@link DatabaseObject#deferSave()} call.
+     */
+    public void save(boolean immediate) {
+        if (this.count < 0 || this.ownerId <= 0) {
+            DatabaseHelper.deleteItem(this);
+            return;
+        }
+
+        if (immediate) {
+            DatabaseObject.super.save();
+        } else {
+            this.save();
+        }
+    }
+
     public SceneWeaponInfo createSceneWeaponInfo() {
         var weaponInfo =
                 SceneWeaponInfo.newBuilder()

src/main/java/emu/grasscutter/game/inventory/Inventory.java

@@ -1,7 +1,5 @@
 package emu.grasscutter.game.inventory;
 
-import static emu.grasscutter.config.Configuration.INVENTORY_LIMITS;
-
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.data.GameData;
 import emu.grasscutter.data.common.ItemParamData;
@@ -18,10 +16,13 @@ import emu.grasscutter.server.packet.send.*;
 import emu.grasscutter.utils.Utils;
 import it.unimi.dsi.fastutil.ints.*;
 import it.unimi.dsi.fastutil.longs.*;
-import java.util.*;
-import javax.annotation.Nullable;
 import lombok.val;
 
+import javax.annotation.Nullable;
+import java.util.*;
+
+import static emu.grasscutter.config.Configuration.INVENTORY_LIMITS;
+
 public class Inventory extends BasePlayerManager implements Iterable<GameItem> {
     private final Long2ObjectMap<GameItem> store;
     private final Int2ObjectMap<InventoryTab> inventoryTypes;
@@ -178,7 +179,7 @@ public class Inventory extends BasePlayerManager implements Iterable<GameItem> {
                 changedItems.add(result);
             }
         }
-        if (changedItems.size() == 0) {
+        if (changedItems.isEmpty()) {
             return;
         }
         if (reason != null) {
@@ -298,8 +299,7 @@ public class Inventory extends BasePlayerManager implements Iterable<GameItem> {
 
         // Add
         switch (type) {
-            case ITEM_WEAPON:
+            case ITEM_WEAPON, ITEM_RELIQUARY -> {
-            case ITEM_RELIQUARY:
                 if (tab.getSize() >= tab.getMaxCapacity()) {
                     return null;
                 }
@@ -310,23 +310,23 @@ public class Inventory extends BasePlayerManager implements Iterable<GameItem> {
                 // Set ownership and save to db
                 item.save();
                 return item;
-            case ITEM_VIRTUAL:
+            }
+            case ITEM_VIRTUAL -> {
                 // Handle
                 this.addVirtualItem(item.getItemId(), item.getCount());
                 return item;
-            default:
+            }
+            default -> {
                 switch (item.getItemData().getMaterialType()) {
-                    case MATERIAL_AVATAR:
+                    case MATERIAL_AVATAR, MATERIAL_FLYCLOAK, MATERIAL_COSTUME, MATERIAL_NAMECARD -> {
-                    case MATERIAL_FLYCLOAK:
-                    case MATERIAL_COSTUME:
-                    case MATERIAL_NAMECARD:
                         Grasscutter.getLogger()
                                 .warn(
                                         "Attempted to add a "
                                                 + item.getItemData().getMaterialType().name()
                                                 + " to inventory, but item definition lacks isUseOnGain. This indicates a Resources error.");
                         return null;
-                    default:
+                    }
+                    default -> {
                         if (tab == null) {
                             return null;
                         }
@@ -353,6 +353,8 @@ public class Inventory extends BasePlayerManager implements Iterable<GameItem> {
                     }
                 }
             }
+        }
+    }
 
     private synchronized void putItem(GameItem item, InventoryTab tab) {
         this.player.getCodex().checkAddedItem(item);

src/main/java/emu/grasscutter/game/player/Player.java

@@ -8,7 +8,7 @@ import emu.grasscutter.data.excels.world.WeatherData;
 import emu.grasscutter.database.DatabaseHelper;
 import emu.grasscutter.game.*;
 import emu.grasscutter.game.ability.AbilityManager;
-import emu.grasscutter.game.achievement.Achievements;
+import emu.grasscutter.game.achievement.*;
 import emu.grasscutter.game.activity.ActivityManager;
 import emu.grasscutter.game.avatar.*;
 import emu.grasscutter.game.battlepass.BattlePassManager;
@@ -55,7 +55,7 @@ import emu.grasscutter.server.game.GameSession.SessionState;
 import emu.grasscutter.server.packet.send.*;
 import emu.grasscutter.utils.*;
 import emu.grasscutter.utils.helpers.DateHelper;
-import emu.grasscutter.utils.objects.FieldFetch;
+import emu.grasscutter.utils.objects.*;
 import it.unimi.dsi.fastutil.ints.*;
 import lombok.*;
 
@@ -66,7 +66,7 @@ import java.util.concurrent.*;
 import static emu.grasscutter.config.Configuration.GAME_OPTIONS;
 
 @Entity(value = "players", useDiscriminator = false)
-public class Player implements PlayerHook, FieldFetch {
+public class Player implements DatabaseObject<Player>, PlayerHook, FieldFetch {
     @Id private int id;
     @Indexed(options = @IndexOptions(unique = true))
     @Getter private String accountId;
@@ -261,6 +261,7 @@ public class Player implements PlayerHook, FieldFetch {
         this.clientAbilityInitFinishHandler = new InvokeHandler(PacketClientAbilityInitFinishNotify.class);
 
         this.birthday = new PlayerBirthday();
+        this.achievements = Achievements.blank();
         this.rewardedLevels = new HashSet<>();
         this.homeRewardedLevels = new HashSet<>();
         this.seenRealmList = new HashSet<>();
@@ -275,8 +276,10 @@ public class Player implements PlayerHook, FieldFetch {
         this.energyManager = new EnergyManager(this);
         this.resinManager = new ResinManager(this);
         this.forgingManager = new ForgingManager(this);
+        this.deforestationManager = new DeforestationManager(this);
         this.progressManager = new PlayerProgressManager(this);
         this.furnitureManager = new FurnitureManager(this);
+        this.battlePassManager = new BattlePassManager(this);
         this.cookingManager = new CookingManager(this);
         this.cookingCompoundManager = new CookingCompoundManager(this);
         this.satiationManager = new SatiationManager(this);
@@ -300,19 +303,6 @@ public class Player implements PlayerHook, FieldFetch {
         this.applyStartingSceneTags();
         this.getFlyCloakList().add(140001);
         this.getNameCardList().add(210001);
-
-        this.mapMarksManager = new MapMarksManager(this);
-        this.staminaManager = new StaminaManager(this);
-        this.sotsManager = new SotSManager(this);
-        this.energyManager = new EnergyManager(this);
-        this.resinManager = new ResinManager(this);
-        this.deforestationManager = new DeforestationManager(this);
-        this.forgingManager = new ForgingManager(this);
-        this.progressManager = new PlayerProgressManager(this);
-        this.furnitureManager = new FurnitureManager(this);
-        this.cookingManager = new CookingManager(this);
-        this.cookingCompoundManager = new CookingCompoundManager(this);
-        this.satiationManager = new SatiationManager(this);
     }
 
     @Override
@@ -1340,8 +1330,25 @@ public class Player implements PlayerHook, FieldFetch {
         this.getTeamManager().setPlayer(this);
     }
 
+    /**
+     * Saves this object to the database.
+     * As of Grasscutter 1.7.1, this is by default a {@link DatabaseObject#deferSave()} call.
+     */
     public void save() {
-        DatabaseHelper.savePlayer(this);
+        this.deferSave();
+    }
+
+    /**
+     * Saves this object to the database.
+     *
+     * @param immediate If true, this will be a {@link DatabaseObject#save()} call instead of a {@link DatabaseObject#deferSave()} call.
+     */
+    public void save(boolean immediate) {
+        if (immediate) {
+            DatabaseObject.super.save();
+        } else {
+            this.save();
+        }
     }
 
     // Called from tokenrsp
@@ -1512,20 +1519,19 @@ public class Player implements PlayerHook, FieldFetch {
             this.getProfile().syncWithCharacter(this);
 
             this.getCoopRequests().clear();
-            this.getEnterHomeRequests().values().forEach(req -> this.expireEnterHomeRequest(req, true));
+            this.getEnterHomeRequests().values()
+                    .forEach(req -> this.expireEnterHomeRequest(req, true));
             this.getEnterHomeRequests().clear();
 
             // Save to db
-            this.save();
+            this.save(true);
             this.getTeamManager().saveAvatars();
             this.getFriendsList().save();
 
             // Call quit event.
-            PlayerQuitEvent event = new PlayerQuitEvent(this);
+            new PlayerQuitEvent(this).call();
-            event.call();
         } catch (Throwable e) {
-            e.printStackTrace();
+            Grasscutter.getLogger().warn("Player (UID {}) failed to save.", this.getUid(), e);
-            Grasscutter.getLogger().warn("Player (UID {}) save failure", getUid());
         } finally {
             removeFromServer();
         }
@@ -1535,7 +1541,8 @@ public class Player implements PlayerHook, FieldFetch {
         // Remove from server.
         // Note: DON'T DELETE BY UID, BECAUSE THERE ARE MULTIPLE SAME UID PLAYERS WHEN DUPLICATED LOGIN!
         //s o I decide to delete by object rather than uid
-        getServer().getPlayers().values().removeIf(player1 -> player1 == this);
+        this.getServer().getPlayers().values()
+                .removeIf(player1 -> player1 == this);
     }
 
     public int getLegendaryKey() {

src/main/java/emu/grasscutter/game/player/TeamManager.java

@@ -4,6 +4,7 @@ import dev.morphia.annotations.*;
 import emu.grasscutter.*;
 import emu.grasscutter.data.GameData;
 import emu.grasscutter.data.excels.avatar.AvatarSkillDepotData;
+import emu.grasscutter.database.Database;
 import emu.grasscutter.game.avatar.Avatar;
 import emu.grasscutter.game.entity.*;
 import emu.grasscutter.game.props.*;
@@ -405,7 +406,7 @@ public final class TeamManager extends BasePlayerDataManager {
         // Unload removed entities
         for (var entity : existingAvatars.values()) {
             this.getPlayer().getScene().removeEntity(entity);
-            entity.getAvatar().save();
+            entity.getAvatar().save(true);
         }
 
         // Set new selected character index
@@ -963,11 +964,13 @@ public final class TeamManager extends BasePlayerDataManager {
         return respawnPoint.get().getPointData().getTranPos();
     }
 
+    /**
+     * Performs a bulk save operation on all avatars.
+     */
     public void saveAvatars() {
-        // Save all avatars from active team
+        Database.saveAll(this.getActiveTeam().stream()
-        for (EntityAvatar entity : this.getActiveTeam()) {
+                .map(EntityAvatar::getAvatar)
-            entity.getAvatar().save();
+                .toList());
-        }
     }
 
     public void onPlayerLogin() { // Hack for now to fix resonances on login

src/main/java/emu/grasscutter/game/quest/QuestManager.java

@@ -1,8 +1,5 @@
 package emu.grasscutter.game.quest;
 
-import static emu.grasscutter.GameConstants.DEBUG;
-import static emu.grasscutter.config.Configuration.*;
-
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.data.GameData;
 import emu.grasscutter.data.binout.*;
@@ -15,12 +12,16 @@ import emu.grasscutter.net.proto.GivingRecordOuterClass.GivingRecord;
 import emu.grasscutter.server.packet.send.*;
 import io.netty.util.concurrent.FastThreadLocalThread;
 import it.unimi.dsi.fastutil.ints.*;
+import lombok.*;
+
+import javax.annotation.Nonnull;
 import java.util.*;
 import java.util.concurrent.*;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
-import javax.annotation.Nonnull;
+
-import lombok.*;
+import static emu.grasscutter.GameConstants.DEBUG;
+import static emu.grasscutter.config.Configuration.*;
 
 public final class QuestManager extends BasePlayerManager {
     @Getter private final Player player;
@@ -569,7 +570,7 @@ public final class QuestManager extends BasePlayerManager {
      * @param quest The ID of the quest.
      */
     public void checkQuestAlreadyFulfilled(GameQuest quest) {
-        Grasscutter.getThreadPool()
+        eventExecutor
                 .submit(
                         () -> {
                             for (var condition : quest.getQuestData().getFinishCond()) {

src/main/java/emu/grasscutter/game/world/World.java

@@ -1,7 +1,5 @@
 package emu.grasscutter.game.world;
 
-import static emu.grasscutter.server.event.player.PlayerTeleportEvent.TeleportType.SCRIPT;
-
 import emu.grasscutter.data.GameData;
 import emu.grasscutter.data.excels.dungeon.DungeonData;
 import emu.grasscutter.game.entity.*;
@@ -20,10 +18,13 @@ import emu.grasscutter.server.game.GameServer;
 import emu.grasscutter.server.packet.send.*;
 import emu.grasscutter.utils.ConversionUtils;
 import it.unimi.dsi.fastutil.ints.*;
-import java.util.*;
 import lombok.*;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.*;
+
+import static emu.grasscutter.server.event.player.PlayerTeleportEvent.TeleportType.SCRIPT;
+
 public class World implements Iterable<Player> {
     @Getter private final GameServer server;
     @Getter private Player host;
@@ -266,7 +267,7 @@ public class World implements Iterable<Player> {
         scene.removePlayer(player);
 
         // Info packet for other players
-        if (this.getPlayers().size() > 0) {
+        if (!this.getPlayers().isEmpty()) {
             this.updatePlayerInfos(player);
         }
 

src/main/java/emu/grasscutter/net/KcpChannel.java

@@ -0,0 +1,22 @@
+package emu.grasscutter.net;
+
+public interface KcpChannel {
+    /**
+     * Event fired when the client connects.
+     *
+     * @param tunnel The tunnel.
+     */
+    void onConnected(KcpTunnel tunnel);
+
+    /**
+     * Event fired when the client disconnects.
+     */
+    void onDisconnected();
+
+    /**
+     * Event fired when data is received from the client.
+     *
+     * @param bytes The data received.
+     */
+    void onMessage(byte[] bytes);
+}

src/main/java/emu/grasscutter/net/KcpTunnel.java

@@ -0,0 +1,22 @@
+package emu.grasscutter.net;
+
+import java.net.InetSocketAddress;
+
+public interface KcpTunnel {
+    /**
+     * @return The address of the client.
+     */
+    InetSocketAddress getAddress();
+
+    /**
+     * Sends bytes to the client.
+     *
+     * @param bytes The bytes to send.
+     */
+    void writeData(byte[] bytes);
+
+    /**
+     * Closes the connection.
+     */
+    void close();
+}

src/main/java/emu/grasscutter/server/game/GameServer.java

@@ -1,55 +1,49 @@
 package emu.grasscutter.server.game;
 
-import static emu.grasscutter.config.Configuration.*;
-import static emu.grasscutter.utils.lang.Language.translate;
-
 import emu.grasscutter.*;
 import emu.grasscutter.Grasscutter.ServerRunMode;
 import emu.grasscutter.database.DatabaseHelper;
 import emu.grasscutter.game.Account;
 import emu.grasscutter.game.battlepass.BattlePassSystem;
-import emu.grasscutter.game.chat.ChatSystem;
+import emu.grasscutter.game.chat.*;
-import emu.grasscutter.game.chat.ChatSystemHandler;
 import emu.grasscutter.game.combine.CombineManger;
-import emu.grasscutter.game.drop.DropSystem;
+import emu.grasscutter.game.drop.*;
-import emu.grasscutter.game.drop.DropSystemLegacy;
 import emu.grasscutter.game.dungeons.DungeonSystem;
 import emu.grasscutter.game.expedition.ExpeditionSystem;
 import emu.grasscutter.game.gacha.GachaSystem;
-import emu.grasscutter.game.home.HomeWorld;
+import emu.grasscutter.game.home.*;
-import emu.grasscutter.game.home.HomeWorldMPSystem;
+import emu.grasscutter.game.managers.cooking.*;
-import emu.grasscutter.game.managers.cooking.CookingCompoundManager;
-import emu.grasscutter.game.managers.cooking.CookingManager;
 import emu.grasscutter.game.managers.energy.EnergyManager;
 import emu.grasscutter.game.managers.stamina.StaminaManager;
 import emu.grasscutter.game.player.Player;
 import emu.grasscutter.game.quest.QuestSystem;
 import emu.grasscutter.game.shop.ShopSystem;
-import emu.grasscutter.game.systems.AnnouncementSystem;
+import emu.grasscutter.game.systems.*;
-import emu.grasscutter.game.systems.InventorySystem;
-import emu.grasscutter.game.systems.MultiplayerSystem;
 import emu.grasscutter.game.talk.TalkSystem;
 import emu.grasscutter.game.tower.TowerSystem;
-import emu.grasscutter.game.world.World;
+import emu.grasscutter.game.world.*;
-import emu.grasscutter.game.world.WorldDataSystem;
 import emu.grasscutter.net.packet.PacketHandler;
 import emu.grasscutter.net.proto.SocialDetailOuterClass.SocialDetail;
 import emu.grasscutter.server.dispatch.DispatchClient;
 import emu.grasscutter.server.event.game.ServerTickEvent;
-import emu.grasscutter.server.event.internal.ServerStartEvent;
+import emu.grasscutter.server.event.internal.*;
-import emu.grasscutter.server.event.internal.ServerStopEvent;
 import emu.grasscutter.server.event.types.ServerEvent;
 import emu.grasscutter.server.scheduler.ServerTaskScheduler;
 import emu.grasscutter.task.TaskMap;
 import emu.grasscutter.utils.Utils;
 import it.unimi.dsi.fastutil.ints.*;
+import kcp.highway.*;
+import lombok.*;
+import org.jetbrains.annotations.*;
+import emu.grasscutter.server.game.session.GameSessionManager;
+
 import java.net.*;
 import java.time.*;
 import java.util.*;
 import java.util.concurrent.*;
-import kcp.highway.*;
+
-import lombok.*;
+import static emu.grasscutter.config.Configuration.*;
-import org.jetbrains.annotations.*;
+import static emu.grasscutter.utils.lang.Language.translate;
 
 @Getter
 public final class GameServer extends KcpServer implements Iterable<Player> {
@@ -60,6 +54,7 @@ public final class GameServer extends KcpServer implements Iterable<Player> {
     private final Set<World> worlds;
     private final Int2ObjectMap<HomeWorld> homeWorlds;
 
+    @Getter private boolean started = false;
     @Setter private DispatchClient dispatchClient;
 
     // Server systems
@@ -140,7 +135,7 @@ public final class GameServer extends KcpServer implements Iterable<Player> {
         channelConfig.setUseConvChannel(true);
         channelConfig.setAckNoDelay(false);
 
-        this.init(GameSessionManager.getListener(), channelConfig, address);
+        this.init(GameSessionManager.getInstance(), channelConfig, address);
 
         EnergyManager.initialize();
         StaminaManager.initialize();
@@ -347,6 +342,8 @@ public final class GameServer extends KcpServer implements Iterable<Player> {
                 .info(translate("messages.game.address_bind", GAME_INFO.accessAddress, address.getPort()));
         ServerStartEvent event = new ServerStartEvent(ServerEvent.Type.GAME, OffsetDateTime.now());
         event.call();
+
+        this.started = true;
     }
 
     public void onServerShutdown() {
@@ -361,10 +358,10 @@ public final class GameServer extends KcpServer implements Iterable<Player> {
         this.stop(); // Stop the server.
 
         try {
-            var threadPool = GameSessionManager.getLogicThread();
+            var threadPool = GameSessionManager.getExecutor();
 
             // Shutdown network thread.
-            threadPool.shutdownGracefully();
+            threadPool.shutdown();
             // Wait for the network thread to finish.
             if (!threadPool.awaitTermination(5, TimeUnit.SECONDS)) {
                 Grasscutter.getLogger().error("Logic thread did not terminate!");

src/main/java/emu/grasscutter/server/game/GameServerPacketHandler.java

@@ -1,7 +1,5 @@
 package emu.grasscutter.server.game;
 
-import static emu.grasscutter.config.Configuration.GAME_INFO;
-
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.Grasscutter.ServerDebugMode;
 import emu.grasscutter.net.packet.*;
@@ -9,6 +7,8 @@ import emu.grasscutter.server.event.game.ReceivePacketEvent;
 import emu.grasscutter.server.game.GameSession.SessionState;
 import it.unimi.dsi.fastutil.ints.*;
 
+import static emu.grasscutter.config.Configuration.GAME_INFO;
+
 public final class GameServerPacketHandler {
     private final Int2ObjectMap<PacketHandler> handlers;
 
@@ -76,13 +76,11 @@ public final class GameServerPacketHandler {
                 }
 
                 // Invoke event.
-                ReceivePacketEvent event = new ReceivePacketEvent(session, opcode, payload);
+                var event = new ReceivePacketEvent(session, opcode, payload);
-                event.call();
+                if (event.call()) // If event is not canceled, continue.
-                if (!event.isCanceled()) // If event is not canceled, continue.
                     handler.handle(session, header, event.getPacketData());
             } catch (Exception ex) {
-                // TODO Remove this when no more needed
+                Grasscutter.getLogger().warn("Unable to handle packet.", ex);
-                ex.printStackTrace();
             }
             return; // Packet successfully handled
         }

src/main/java/emu/grasscutter/server/game/GameSession.java

@@ -1,24 +1,26 @@
 package emu.grasscutter.server.game;
 
-import static emu.grasscutter.config.Configuration.*;
-import static emu.grasscutter.utils.lang.Language.translate;
-
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.Grasscutter.ServerDebugMode;
 import emu.grasscutter.game.Account;
 import emu.grasscutter.game.player.Player;
+import emu.grasscutter.net.*;
 import emu.grasscutter.net.packet.*;
 import emu.grasscutter.server.event.game.SendPacketEvent;
 import emu.grasscutter.utils.*;
 import io.netty.buffer.*;
+import lombok.*;
+
 import java.io.File;
 import java.net.InetSocketAddress;
 import java.nio.file.Path;
-import lombok.*;
 
-public class GameSession implements GameSessionManager.KcpChannel {
+import static emu.grasscutter.config.Configuration.*;
+import static emu.grasscutter.utils.lang.Language.translate;
+
+public class GameSession implements KcpChannel {
     private final GameServer server;
-    private GameSessionManager.KcpTunnel tunnel;
+    private KcpTunnel tunnel;
 
     @Getter @Setter private Account account;
     @Getter private Player player;
@@ -146,7 +148,7 @@ public class GameSession implements GameSessionManager.KcpChannel {
                 if (packet.shouldEncrypt) {
                     Crypto.xor(bytes, packet.useDispatchKey() ? Crypto.DISPATCH_KEY : this.encryptKey);
                 }
-                tunnel.writeData(bytes);
+                this.tunnel.writeData(bytes);
             } catch (Exception ignored) {
                 Grasscutter.getLogger().debug("Unable to send packet to client.");
             }
@@ -154,13 +156,13 @@ public class GameSession implements GameSessionManager.KcpChannel {
     }
 
     @Override
-    public void onConnected(GameSessionManager.KcpTunnel tunnel) {
+    public void onConnected(KcpTunnel tunnel) {
         this.tunnel = tunnel;
         Grasscutter.getLogger().info(translate("messages.game.connect", this.getAddress().toString()));
     }
 
     @Override
-    public void handleReceive(byte[] bytes) {
+    public void onMessage(byte[] bytes) {
         // Decrypt and turn back into a packet
         Crypto.xor(bytes, useSecretKey() ? this.encryptKey : Crypto.DISPATCH_KEY);
         ByteBuf packet = Unpooled.wrappedBuffer(bytes);
@@ -226,8 +228,8 @@ public class GameSession implements GameSessionManager.KcpChannel {
                 // Handle
                 getServer().getPacketHandler().handle(this, opcode, header, payload);
             }
-        } catch (Exception e) {
+        } catch (Exception exception) {
-            e.printStackTrace();
+            Grasscutter.getLogger().warn("Unable to handle packet.", exception);
         } finally {
             // byteBuf.release(); //Needn't
             packet.release();
@@ -235,8 +237,9 @@ public class GameSession implements GameSessionManager.KcpChannel {
     }
 
     @Override
-    public void handleClose() {
+    public void onDisconnected() {
         setState(SessionState.INACTIVE);
+
         // send disconnection pack in case of reconnection
         Grasscutter.getLogger()
                 .info(translate("messages.game.disconnect", this.getAddress().toString()));

src/main/java/emu/grasscutter/server/game/GameSessionManager.java

@@ -1,114 +0,0 @@
-package emu.grasscutter.server.game;
-
-import emu.grasscutter.Grasscutter;
-import emu.grasscutter.utils.Utils;
-import io.netty.buffer.*;
-import io.netty.channel.DefaultEventLoop;
-import java.net.InetSocketAddress;
-import java.util.concurrent.ConcurrentHashMap;
-import kcp.highway.*;
-import lombok.Getter;
-
-public class GameSessionManager {
-    @Getter private static final DefaultEventLoop logicThread = new DefaultEventLoop();
-    private static final ConcurrentHashMap<Ukcp, GameSession> sessions = new ConcurrentHashMap<>();
-    private static final KcpListener listener =
-            new KcpListener() {
-                @Override
-                public void onConnected(Ukcp ukcp) {
-                    int times = 0;
-                    GameServer server = Grasscutter.getGameServer();
-                    while (server == null) { // Waiting server to establish
-                        try {
-                            Thread.sleep(1000);
-                        } catch (InterruptedException e) {
-                            e.printStackTrace();
-                            ukcp.close();
-                            return;
-                        }
-                        if (times++ > 5) {
-                            Grasscutter.getLogger().error("Service is not available!");
-                            ukcp.close();
-                            return;
-                        }
-                        server = Grasscutter.getGameServer();
-                    }
-                    GameSession conversation = new GameSession(server);
-                    conversation.onConnected(
-                            new KcpTunnel() {
-                                @Override
-                                public InetSocketAddress getAddress() {
-                                    return ukcp.user().getRemoteAddress();
-                                }
-
-                                @Override
-                                public void writeData(byte[] bytes) {
-                                    ByteBuf buf = Unpooled.wrappedBuffer(bytes);
-                                    ukcp.write(buf);
-                                    buf.release();
-                                }
-
-                                @Override
-                                public void close() {
-                                    ukcp.close();
-                                }
-
-                                @Override
-                                public int getSrtt() {
-                                    return ukcp.srtt();
-                                }
-                            });
-                    sessions.put(ukcp, conversation);
-                }
-
-                @Override
-                public void handleReceive(ByteBuf buf, Ukcp kcp) {
-                    var byteData = Utils.byteBufToArray(buf);
-                    logicThread.execute(
-                            () -> {
-                                try {
-                                    var conversation = sessions.get(kcp);
-                                    if (conversation != null) {
-                                        conversation.handleReceive(byteData);
-                                    }
-                                } catch (Exception e) {
-                                    e.printStackTrace();
-                                }
-                            });
-                }
-
-                @Override
-                public void handleException(Throwable ex, Ukcp ukcp) {}
-
-                @Override
-                public void handleClose(Ukcp ukcp) {
-                    GameSession conversation = sessions.get(ukcp);
-                    if (conversation != null) {
-                        conversation.handleClose();
-                        sessions.remove(ukcp);
-                    }
-                }
-            };
-
-    public static KcpListener getListener() {
-        return listener;
-    }
-
-    public interface KcpTunnel {
-        InetSocketAddress getAddress();
-
-        void writeData(byte[] bytes);
-
-        void close();
-
-        int getSrtt();
-    }
-
-    interface KcpChannel {
-        void onConnected(KcpTunnel tunnel);
-
-        void handleClose();
-
-        void handleReceive(byte[] bytes);
-    }
-}

src/main/java/emu/grasscutter/server/game/session/GameSessionHandler.java

@@ -0,0 +1,31 @@
+package emu.grasscutter.server.game.session;
+
+import emu.grasscutter.net.KcpTunnel;
+import io.netty.buffer.Unpooled;
+import kcp.highway.Ukcp;
+import lombok.*;
+
+import java.net.InetSocketAddress;
+
+@RequiredArgsConstructor
+public final class GameSessionHandler implements KcpTunnel {
+    @Getter private final Ukcp handle;
+
+    @Override
+    public InetSocketAddress getAddress() {
+        return this.getHandle().user().getRemoteAddress();
+    }
+
+    @Override
+    public void writeData(byte[] bytes) {
+        var buffer = Unpooled.wrappedBuffer(bytes);
+        this.getHandle().write(buffer);
+
+        buffer.release();
+    }
+
+    @Override
+    public void close() {
+        this.getHandle().close();
+    }
+}

src/main/java/emu/grasscutter/server/game/session/GameSessionManager.java

@@ -0,0 +1,89 @@
+package emu.grasscutter.server.game.session;
+
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.server.game.*;
+import emu.grasscutter.utils.Utils;
+import io.netty.buffer.ByteBuf;
+import kcp.highway.*;
+import lombok.Getter;
+
+import java.util.Map;
+import java.util.concurrent.*;
+
+public final class GameSessionManager implements KcpListener {
+    @Getter private static final GameSessionManager instance
+        = new GameSessionManager();
+    @Getter private static final ExecutorService executor
+        = Executors.newWorkStealingPool();
+    @Getter private static final Map<Ukcp, GameSession> sessions
+        = new ConcurrentHashMap<>();
+
+    /**
+     * Waits for the game server to be ready.
+     *
+     * @return The game server.
+     */
+    private GameServer waitForServer() {
+        var server = Grasscutter.getGameServer();
+        var times = 0; while (server == null || !server.isStarted()) {
+            Utils.sleep(1000); // Wait 1s for the server to start.
+            if (times++ > 5) {
+                Grasscutter.getLogger().error("Game server has not started in a reasonable time.");
+                return null;
+            }
+
+            server = Grasscutter.getGameServer();
+        }
+
+        return server;
+    }
+
+    @Override
+    public void onConnected(Ukcp ukcp) {
+        // Fetch the game server.
+        var server = this.waitForServer();
+        if (server == null) {
+            ukcp.close();
+            return;
+        }
+
+        // Create a new session.
+        var session = sessions.compute(ukcp, (k, existing) -> {
+            // Close an existing session.
+            if (existing != null) {
+                existing.close();
+            }
+
+            return new GameSession(server);
+        });
+
+        // Connect the session.
+        session.onConnected(new GameSessionHandler(ukcp));
+    }
+
+    @Override
+    public void handleReceive(ByteBuf byteBuf, Ukcp ukcp) {
+        // Get the session.
+        var session = sessions.get(ukcp);
+        if (session == null) {
+            ukcp.close(); return;
+        }
+
+        // Handle the message in a separate thread.
+        var bytes = Utils.byteBufToArray(byteBuf);
+        executor.submit(() -> session.onMessage(bytes));
+    }
+
+    @Override
+    public void handleException(Throwable throwable, Ukcp ukcp) {
+        Grasscutter.getLogger().error("Exception in game session.", throwable);
+    }
+
+    @Override
+    public void handleClose(Ukcp ukcp) {
+        var session = sessions.remove(ukcp);
+        if (session != null) {
+            session.close();
+        }
+    }
+}

src/main/java/emu/grasscutter/utils/objects/DatabaseObject.java

@@ -0,0 +1,42 @@
+package emu.grasscutter.utils.objects;
+
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.Grasscutter.ServerRunMode;
+import emu.grasscutter.database.*;
+
+public interface DatabaseObject<T> {
+    /**
+     * @return Does this object belong in the game database?
+     */
+    default boolean isGameObject() {
+        return true;
+    }
+
+    /**
+     * @return Should this object be saved immediately?
+     */
+    default boolean saveImmediately() {
+        return false;
+    }
+
+    /**
+     * Performs a deferred save.
+     * This object will save as a group with other objects.
+     */
+    default void deferSave() {
+        Database.save(this);
+    }
+
+    /**
+     * Attempts to save this object to the database.
+     */
+    default void save() {
+        if (this.isGameObject()) {
+            DatabaseManager.getGameDatastore().save(this);
+        } else if (Grasscutter.getRunMode() != ServerRunMode.GAME_ONLY) {
+            DatabaseManager.getAccountDatastore().save(this);
+        } else {
+            throw new UnsupportedOperationException("Unable to store an account object while in game-only mode.");
+        }
+    }
+}

src/test/java/io/grasscutter/GrasscutterTest.java

@@ -1,60 +1,18 @@
 package io.grasscutter;
 
-import com.mchange.util.AssertException;
+import io.grasscutter.virtual.*;
-import emu.grasscutter.Grasscutter;
+import lombok.*;
-import emu.grasscutter.config.Configuration;
-import java.io.IOException;
-import lombok.Getter;
 import okhttp3.OkHttpClient;
-import okhttp3.Request;
-import org.junit.jupiter.api.Assertions;
-import org.junit.jupiter.api.BeforeAll;
-import org.junit.jupiter.api.DisplayName;
-import org.junit.jupiter.api.Test;
 
-/** Testing entrypoint for {@link Grasscutter}. */
+import java.util.concurrent.*;
+
 public final class GrasscutterTest {
-    @Getter private static final OkHttpClient httpClient = new OkHttpClient();
+    @Getter
+    public static final OkHttpClient httpClient = new OkHttpClient();
+    @Getter public static final ExecutorService executor = Executors.newSingleThreadExecutor();
 
-    @Getter private static int httpPort = -1;
+    @Getter public static VirtualAccount account;
-    @Getter private static int gamePort = -1;
+    @Setter
-
+    @Getter public static VirtualPlayer player;
-    /**
+    @Getter public static VirtualGameSession gameSession;
-     * Creates an HTTP URL.
-     *
-     * @param route The route to use.
-     * @return The URL.
-     */
-    public static String http(String route) {
-        return "http://127.0.0.1:" + GrasscutterTest.httpPort + "/" + route;
-    }
-
-    @BeforeAll
-    public static void entry() {
-        try {
-            // Start Grasscutter.
-            Grasscutter.main(new String[] {"-test"});
-        } catch (Exception ignored) {
-            throw new AssertException("Grasscutter failed to start.");
-        }
-
-        // Set the ports.
-        GrasscutterTest.httpPort = Configuration.SERVER.http.bindPort;
-        GrasscutterTest.gamePort = Configuration.SERVER.game.bindPort;
-    }
-
-    @Test
-    @DisplayName("HTTP server check")
-    public void checkHttpServer() {
-        // Create a request.
-        var request = new Request.Builder().url(GrasscutterTest.http("")).build();
-
-        // Perform the request.
-        try (var response = GrasscutterTest.httpClient.newCall(request).execute()) {
-            // Check the response.
-            Assertions.assertTrue(response.isSuccessful());
-        } catch (IOException exception) {
-            throw new AssertionError(exception);
-        }
-    }
 }

src/test/java/io/grasscutter/TestUtils.java

@@ -0,0 +1,17 @@
+package io.grasscutter;
+
+import emu.grasscutter.utils.Utils;
+import emu.grasscutter.utils.objects.Returnable;
+
+public interface TestUtils {
+    /**
+     * Waits for a condition to be met.
+     *
+     * @param condition The condition.
+     */
+    static void waitFor(Returnable<Boolean> condition) {
+        while (!condition.invoke()) {
+            Utils.sleep(100);
+        }
+    }
+}

src/test/java/io/grasscutter/tests/BaseServerTest.java

@@ -0,0 +1,61 @@
+package io.grasscutter.tests;
+
+import com.mchange.util.AssertException;
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.config.Configuration;
+import io.grasscutter.GrasscutterTest;
+import io.grasscutter.virtual.*;
+import lombok.*;
+import okhttp3.*;
+import org.junit.jupiter.api.*;
+
+import java.io.IOException;
+
+/** Testing entrypoint for {@link Grasscutter}. */
+public final class BaseServerTest {
+    @Getter private static int httpPort = -1;
+    @Getter private static int gamePort = -1;
+
+    /**
+     * Creates an HTTP URL.
+     *
+     * @param route The route to use.
+     * @return The URL.
+     */
+    public static String http(String route) {
+        return "http://127.0.0.1:" + BaseServerTest.httpPort + "/" + route;
+    }
+
+    @BeforeAll
+    public static void entry() {
+        try {
+            // Start Grasscutter.
+            Grasscutter.main(new String[] {"-test"});
+        } catch (Exception ignored) {
+            throw new AssertException("Grasscutter failed to start.");
+        }
+
+        // Set the ports.
+        BaseServerTest.httpPort = Configuration.SERVER.http.bindPort;
+        BaseServerTest.gamePort = Configuration.SERVER.game.bindPort;
+
+        // Create virtual instances.
+        GrasscutterTest.account = new VirtualAccount();
+        GrasscutterTest.gameSession = new VirtualGameSession();
+    }
+
+    @Test
+    @DisplayName("HTTP server check")
+    public void checkHttpServer() {
+        // Create a request.
+        var request = new Request.Builder().url(BaseServerTest.http("")).build();
+
+        // Perform the request.
+        try (var response = GrasscutterTest.httpClient.newCall(request).execute()) {
+            // Check the response.
+            Assertions.assertTrue(response.isSuccessful());
+        } catch (IOException exception) {
+            throw new AssertionError(exception);
+        }
+    }
+}

src/test/java/io/grasscutter/tests/LoginTest.java

@@ -0,0 +1,67 @@
+package io.grasscutter.tests;
+
+import emu.grasscutter.GameConstants;
+import emu.grasscutter.net.packet.PacketOpcodes;
+import emu.grasscutter.net.proto.*;
+import emu.grasscutter.server.game.session.GameSessionManager;
+import io.grasscutter.*;
+import kcp.highway.*;
+import lombok.Getter;
+import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;
+
+@TestMethodOrder(OrderAnnotation.class)
+public final class LoginTest {
+    @Getter private static final Ukcp KCP = new Ukcp(
+        null, null, null,
+        new ChannelConfig(), null);
+
+    @Test
+    @Order(1)
+    @DisplayName("Connect to server")
+    public void connectToServer() {
+        var session = GrasscutterTest.getGameSession();
+
+        // Register the session.
+        GameSessionManager.getSessions().put(KCP, session);
+
+        // Try connecting to the server.
+        session.exchangeToken();
+        Assertions.assertTrue(session.waitForPacket(
+                PacketOpcodes.GetPlayerTokenRsp, 5));
+    }
+
+    @Test
+    @Order(2)
+    @DisplayName("Login to server")
+    public void loginToServer() {
+        var account = GrasscutterTest.getAccount();
+        var session = GrasscutterTest.getGameSession();
+
+        // Wait for the login response.
+        TestUtils.waitFor(session::useSecretKey);
+
+        // Send the login packet.
+        session.receive(
+                PacketOpcodes.PlayerLoginReq,
+                PlayerLoginReqOuterClass.PlayerLoginReq.newBuilder()
+                        .setToken(account.getToken())
+                        .build()
+        );
+        // Wait for the login response.
+        Assertions.assertTrue(session.waitForPacket(
+                PacketOpcodes.PlayerLoginRsp, 5));
+
+        // Send the born data request.
+        session.receive(
+                PacketOpcodes.SetPlayerBornDataReq,
+                SetPlayerBornDataReqOuterClass.SetPlayerBornDataReq.newBuilder()
+                        .setAvatarId(GameConstants.MAIN_CHARACTER_FEMALE)
+                        .setNickName("Virtual Player")
+                        .build()
+        );
+        // Wait for the born data response.
+        Assertions.assertTrue(session.waitForPacket(
+                PacketOpcodes.SetPlayerBornDataRsp, 5));
+    }
+}

src/test/java/io/grasscutter/virtual/VirtualAccount.java

@@ -0,0 +1,23 @@
+package io.grasscutter.virtual;
+
+import emu.grasscutter.game.Account;
+
+import java.util.Locale;
+
+@SuppressWarnings("deprecation")
+public final class VirtualAccount extends Account {
+    public VirtualAccount() {
+        super();
+
+        this.setId("virtual_account");
+        this.setUsername("virtual_account");
+        this.setPassword("virtual_account");
+
+        this.setReservedPlayerUid(10001);
+        this.setEmail("virtual_account@grasscutter.io");
+        this.setLocale(Locale.US);
+
+        this.generateSessionKey();
+        this.generateLoginToken();
+    }
+}

src/test/java/io/grasscutter/virtual/VirtualGameSession.java

@@ -0,0 +1,142 @@
+package io.grasscutter.virtual;
+
+import com.google.protobuf.GeneratedMessageV3;
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.game.player.Player;
+import emu.grasscutter.net.packet.*;
+import emu.grasscutter.net.proto.GetPlayerTokenReqOuterClass.GetPlayerTokenReq;
+import emu.grasscutter.net.proto.PacketHeadOuterClass.PacketHead;
+import emu.grasscutter.server.game.GameSession;
+import emu.grasscutter.utils.Crypto;
+import io.grasscutter.GrasscutterTest;
+import io.netty.buffer.Unpooled;
+import org.slf4j.*;
+
+import java.util.*;
+import java.util.concurrent.*;
+import java.util.function.Function;
+
+public final class VirtualGameSession extends GameSession {
+    private static final Logger logger = LoggerFactory.getLogger("Game Session");
+
+    private final Map<Integer, Set<Function<byte[], Boolean>>> listeners = new HashMap<>();
+
+    public VirtualGameSession() {
+        super(Grasscutter.getGameServer());
+
+        this.setAccount(GrasscutterTest.getAccount());
+        this.onConnected(new VirtualKcpTunnel());
+    }
+
+    /**
+     * Performs an exchange with the server for the player's token.
+     */
+    public void exchangeToken() {
+        var account = GrasscutterTest.getAccount();
+
+        this.receive(
+                PacketOpcodes.GetPlayerTokenReq,
+                GetPlayerTokenReq.newBuilder()
+                        .setAccountUid(account.getId())
+                        .setAccountToken(account.getToken())
+                        .build()
+        );
+    }
+
+    /**
+     * Registers a listener for a packet.
+     *
+     * @param packetId The packet's ID.
+     * @param listener The listener to register.
+     */
+    public void addPacketListener(int packetId, Function<byte[], Boolean> listener) {
+        var listeners = this.listeners.computeIfAbsent(
+                packetId, k -> new HashSet<>());
+        listeners.add(listener);
+    }
+
+    /**
+     * Waits for a packet to be received.
+     *
+     * @param packetId The packet's ID.
+     * @param timeout The timeout in milliseconds.
+     */
+    public boolean waitForPacket(int packetId, int timeout) {
+        var promise = new CompletableFuture<byte[]>();
+        this.addPacketListener(packetId, data -> {
+            promise.complete(data);
+            return false;
+        });
+
+        try {
+            promise.get(timeout, TimeUnit.SECONDS);
+            return true;
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public synchronized void setPlayer(Player player) {
+        var newPlayer = new VirtualPlayer();
+
+        GrasscutterTest.setPlayer(newPlayer);
+        super.setPlayer(newPlayer);
+    }
+
+    /**
+     * Receives a packet from the client.
+     *
+     * @param packetId The packet's ID.
+     * @param message The packet to receive.
+     */
+    public void receive(int packetId, GeneratedMessageV3 message) {
+        // Craft a packet header.
+        var header = PacketHead.newBuilder()
+                .setSentMs(System.currentTimeMillis())
+                .build();
+        // Serialize the message.
+        var headerBytes = header.toByteArray();
+        var messageBytes = message.toByteArray();
+
+        // Wrap the message into a packet.
+        var packet = Unpooled.buffer(12);
+        packet.writeShort(17767); // Packet header.
+        packet.writeShort(packetId); // Packet "opcode" or ID.
+        packet.writeShort(headerBytes.length); // Packet head length.
+        packet.writeInt(messageBytes.length); // Packet body length.
+        packet.writeBytes(headerBytes); // Packet head.
+        packet.writeBytes(messageBytes); // Packet body.
+        packet.writeShort(-30293); // Packet footer.
+
+        // Serialize the packet.
+        var data = packet.array();
+        // Encrypt the packet if specified.
+        Crypto.xor(data, this.useSecretKey() ?
+                Crypto.ENCRYPT_KEY : Crypto.DISPATCH_KEY);
+
+        // Dispatch the message to the server.
+        GrasscutterTest.getExecutor()
+                .submit(() -> this.onMessage(data));
+    }
+
+    @Override
+    public void send(BasePacket packet) {
+        // Invoke packet handlers.
+        var listeners = this.listeners.get(packet.getOpcode());
+        if (listeners != null) {
+            var copy = new HashSet<>(listeners);
+            for (var listener : copy) {
+                if (listener.apply(packet.getData())) {
+                    listeners.remove(listener);
+                }
+            }
+        }
+
+        // Log the received packet.
+        logger.info("Received packet {} ({}) of length {} (header is {}).",
+            PacketOpcodesUtils.getOpcodeName(packet.getOpcode()), packet.getOpcode(),
+            packet.getData() == null ? "null" : packet.getData().length,
+            packet.getHeader() == null ? "null" : packet.getHeader().length);
+    }
+}

src/test/java/io/grasscutter/virtual/VirtualKcpTunnel.java

@@ -0,0 +1,21 @@
+package io.grasscutter.virtual;
+
+import emu.grasscutter.net.KcpTunnel;
+import java.net.InetSocketAddress;
+
+public final class VirtualKcpTunnel implements KcpTunnel {
+    @Override
+    public InetSocketAddress getAddress() {
+        return new InetSocketAddress(1000);
+    }
+
+    @Override
+    public void writeData(byte[] bytes) {
+        throw new UnsupportedOperationException("Cannot write to a virtual KCP tunnel");
+    }
+
+    @Override
+    public void close() {
+        System.exit(0);
+    }
+}

src/test/java/io/grasscutter/virtual/VirtualPlayer.java

@@ -0,0 +1,13 @@
+package io.grasscutter.virtual;
+
+import emu.grasscutter.game.player.Player;
+import io.grasscutter.GrasscutterTest;
+import io.grasscutter.tests.BaseServerTest;
+
+public final class VirtualPlayer extends Player {
+    public VirtualPlayer() {
+        super(GrasscutterTest.getGameSession());
+
+        this.setAccount(GrasscutterTest.getAccount());
+    }
+}