Add SessionDisconnectEvent (#4052)

* Add SessionDisconnectEvent

* Move disconnect event calling to UpstreamSession, debug double calling issues

* Prevent duplicate disconnect calling

* Tidy up disconnection logic, ensure SessionDisconnectEvent is always fired - but only once. Fix /geyser reload command

api/src/main/java/org/geysermc/geyser/api/event/bedrock/SessionDisconnectEvent.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2019-2023 GeyserMC. http://geysermc.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @author GeyserMC
+ * @link https://github.com/GeyserMC/Geyser
+ */
+
+package org.geysermc.geyser.api.event.bedrock;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.geysermc.geyser.api.connection.GeyserConnection;
+import org.geysermc.geyser.api.event.connection.ConnectionEvent;
+
+/**
+ * Called when a Geyser session disconnects.
+ */
+public class SessionDisconnectEvent extends ConnectionEvent {
+    private String disconnectReason;
+
+    public SessionDisconnectEvent(@NonNull GeyserConnection connection, @NonNull String reason) {
+        super(connection);
+        this.disconnectReason = reason;
+    }
+
+    /**
+     * Gets the disconnect reason.
+     *
+     * @return the reason for the disconnect
+     */
+    public @NonNull String disconnectReason() {
+        return disconnectReason;
+    }
+
+    /**
+     * Sets the disconnect reason, thereby overriding th original reason.
+     *
+     * @param disconnectReason the reason for the disconnect
+     */
+    public void disconnectReason(@NonNull String disconnectReason) {
+        this.disconnectReason = disconnectReason;
+    }
+}
+

core/src/main/java/org/geysermc/geyser/command/defaults/ReloadCommand.java

@@ -32,6 +32,8 @@ import org.geysermc.geyser.command.GeyserCommandSource;
 import org.geysermc.geyser.session.GeyserSession;
 import org.geysermc.geyser.text.GeyserLocale;
 
+import java.util.concurrent.TimeUnit;
+
 public class ReloadCommand extends GeyserCommand {
 
     private final GeyserImpl geyser;
@@ -52,7 +54,8 @@ public class ReloadCommand extends GeyserCommand {
         sender.sendMessage(message);
 
         geyser.getSessionManager().disconnectAll("geyser.commands.reload.kick");
-        geyser.reload();
+        //FIXME Without the tiny wait, players do not get kicked - same happens when Geyser tries to disconnect all sessions on shutdown
+        geyser.getScheduledThread().schedule(geyser::reload, 10, TimeUnit.MILLISECONDS);
     }
 
     @Override

core/src/main/java/org/geysermc/geyser/session/GeyserSession.java

@@ -105,6 +105,7 @@ import org.geysermc.geyser.api.bedrock.camera.CameraShake;
 import org.geysermc.geyser.api.connection.GeyserConnection;
 import org.geysermc.geyser.api.entity.type.GeyserEntity;
 import org.geysermc.geyser.api.entity.type.player.GeyserPlayerEntity;
+import org.geysermc.geyser.api.event.bedrock.SessionDisconnectEvent;
 import org.geysermc.geyser.api.event.bedrock.SessionLoginEvent;
 import org.geysermc.geyser.api.network.AuthType;
 import org.geysermc.geyser.api.network.RemoteServer;
@@ -1038,10 +1039,14 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
                     geyser.getLogger().info(GeyserLocale.getLocaleStringLog("geyser.network.remote.disconnect", authData.name(), remoteServer.address(), disconnectMessage));
                 }
                 if (cause != null) {
-                    cause.printStackTrace();
+                    GeyserImpl.getInstance().getLogger().error(cause.getMessage());
+                    // GeyserSession is disconnected via session.disconnect() called indirectly be the server
+                    // This only needs to be "initiated" here when there is an exception, hence the cause clause
+                    GeyserSession.this.disconnect(disconnectMessage);
+                    if (geyser.getConfig().isDebugMode()) {
+                        cause.printStackTrace();
+                    }
                 }
-
-                upstream.disconnect(disconnectMessage);
             }
 
             @Override
@@ -1068,17 +1073,30 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
     public void disconnect(String reason) {
         if (!closed) {
             loggedIn = false;
+
+            // Fire SessionDisconnectEvent
+            SessionDisconnectEvent disconnectEvent = new SessionDisconnectEvent(this, reason);
+            geyser.getEventBus().fire(disconnectEvent);
+
+            // Disconnect downstream if necessary
             if (downstream != null) {
-                downstream.disconnect(reason);
+                // No need to disconnect if already closed
+                if (!downstream.isClosed()) {
+                    downstream.disconnect(reason);
+                }
             } else {
                 // Downstream's disconnect will fire an event that prints a log message
                 // Otherwise, we print a message here
                 String address = geyser.getConfig().isLogPlayerIpAddresses() ? upstream.getAddress().getAddress().toString() : "<IP address withheld>";
                 geyser.getLogger().info(GeyserLocale.getLocaleStringLog("geyser.network.disconnect", address, reason));
             }
+
+            // Disconnect upstream if necessary
             if (!upstream.isClosed()) {
-                upstream.disconnect(reason);
+                upstream.disconnect(disconnectEvent.disconnectReason());
             }
+
+            // Remove from session manager
             geyser.getSessionManager().removeSession(this);
             if (authData != null) {
                 PendingMicrosoftAuthentication.AuthenticationTask task = geyser.getPendingMicrosoftAuthentication().getTask(authData.xuid());

core/src/main/java/org/geysermc/geyser/session/UpstreamSession.java

@@ -58,7 +58,7 @@ public class UpstreamSession {
     }
 
     public void disconnect(String reason) {
-        session.disconnect(reason);
+        this.session.disconnect(reason);
     }
 
     /**