feat: Add OnlineServerCache

Author: 4drian3d

src/main/java/io/github/_4drian3d/authmevelocity/lastserver/database/OnlineServerCache.java

@@ -0,0 +1,34 @@
+package io.github._4drian3d.authmevelocity.lastserver.database;
+
+import com.github.benmanes.caffeine.cache.Caffeine;
+import com.github.benmanes.caffeine.cache.LoadingCache;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+import com.velocitypowered.api.proxy.ProxyServer;
+import com.velocitypowered.api.proxy.server.RegisteredServer;
+
+import java.util.concurrent.TimeUnit;
+
+@Singleton
+public class OnlineServerCache {
+    private final LoadingCache<String, Boolean> cache;
+
+    @Inject
+    public OnlineServerCache(final ProxyServer proxyServer) {
+        this.cache =  Caffeine.newBuilder()
+                .expireAfterWrite(3, TimeUnit.MINUTES)
+                .build(server -> proxyServer.getServer(server)
+                        .filter(registeredServer -> registeredServer.ping()
+                                .handle((ping, throwable) -> ping != null)
+                                .join())
+                        .isPresent());
+    }
+
+    public boolean isOnline(final String server) {
+        return this.cache.get(server);
+    }
+
+    public boolean isOnline(final RegisteredServer server) {
+        return this.isOnline(server.getServerInfo().getName());
+    }
+}

src/main/java/io/github/_4drian3d/authmevelocity/lastserver/listener/PreSendOnLoginListener.java

@@ -3,13 +3,12 @@
 import com.google.inject.Inject;
 import com.velocitypowered.api.event.EventManager;
 import com.velocitypowered.api.event.EventTask;
-import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.ProxyServer;
 import io.github._4drian3d.authmevelocity.api.velocity.event.PreSendOnLoginEvent;
 import io.github._4drian3d.authmevelocity.api.velocity.event.ServerResult;
 import io.github._4drian3d.authmevelocity.lastserver.LastServerAddon;
 import io.github._4drian3d.authmevelocity.lastserver.database.Database;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import io.github._4drian3d.authmevelocity.lastserver.database.OnlineServerCache;
 
 public final class PreSendOnLoginListener implements LastLoginListener<PreSendOnLoginEvent> {
     @Inject
@@ -20,6 +19,8 @@ public final class PreSendOnLoginListener implements LastLoginListener<PreSendOn
     private LastServerAddon plugin;
     @Inject
     private Database database;
+    @Inject
+    private OnlineServerCache serverCache;
 
     @Override
     public EventTask executeAsync(final PreSendOnLoginEvent event) {
@@ -28,6 +29,7 @@ public EventTask executeAsync(final PreSendOnLoginEvent event) {
             final String newServer = this.database.lastServerOf(player);
             if (newServer != null) {
                 this.proxyServer.getServer(newServer)
+                        .filter(serverCache::isOnline)
                         .ifPresent(server -> event.setResult(ServerResult.allowed(server)));
             }
             continuation.resume();