Cache boss bar title conversions for 1.8 clients

common/src/main/java/com/viaversion/viarewind/ViaRewindConfig.java

@@ -40,6 +40,7 @@ public class ViaRewindConfig extends Config implements com.viaversion.viarewind.
     private String offhandCommand;
     private boolean emulateLevitationEffect;
     private boolean handlePlayerCombatPacket;
+    private boolean cacheBossBarTextConversion;
 
     public ViaRewindConfig(File configFile, Logger logger) {
         super(configFile, logger);
@@ -64,6 +65,7 @@ private void loadFields() {
         offhandCommand = getString("offhand-command", "/offhand");
         emulateLevitationEffect = getBoolean("emulate-levitation-effect", true);
         handlePlayerCombatPacket = getBoolean("handle-player-combat-packet", true);
+        cacheBossBarTextConversion = getBoolean("cache-bossbar-text-conversion", true);
     }
 
     @Override
@@ -126,6 +128,11 @@ public boolean handlePlayerCombatPacket() {
         return handlePlayerCombatPacket;
     }
 
+    @Override
+    public boolean cacheBossBarTextConversion() {
+        return cacheBossBarTextConversion;
+    }
+
     @Override
     public URL getDefaultConfigURL() {
         return getClass().getClassLoader().getResource("assets/viarewind/config.yml");

common/src/main/java/com/viaversion/viarewind/api/ViaRewindConfig.java

@@ -114,6 +114,14 @@ public interface ViaRewindConfig extends Config {
      */
     boolean handlePlayerCombatPacket();
 
+    /**
+     * Caches the legacy text conversion of boss bar titles for 1.8 players.
+     * Plugins often resend the same title to every online player, so most conversions can be reused.
+     *
+     * @return true if enabled
+     */
+    boolean cacheBossBarTextConversion();
+
     enum CooldownIndicator {
         TITLE, ACTION_BAR, BOSS_BAR, DISABLED
     }

common/src/main/java/com/viaversion/viarewind/protocol/v1_9to1_8/rewriter/PlayerPacketRewriter1_9.java

@@ -80,15 +80,15 @@ protected void registerPackets() {
                 wrapper.read(Types.VAR_INT); // Division
                 wrapper.read(Types.UNSIGNED_BYTE); // Flags
 
-                bossbar.add(uuid, ChatUtil.jsonToLegacy(title), health);
+                bossbar.add(uuid, bossBarTitleToLegacy(title), health);
             } else if (action == 1 /* remove */) {
                 bossbar.remove(uuid);
             } else if (action == 2 /* update health */) {
                 final float health = wrapper.read(Types.FLOAT);
                 bossbar.updateHealth(uuid, health);
             } else if (action == 3 /* update title */) {
                 final JsonElement title = wrapper.read(Types.COMPONENT);
-                bossbar.updateTitle(uuid, ChatUtil.jsonToLegacy(title));
+                bossbar.updateTitle(uuid, bossBarTitleToLegacy(title));
             }
         });
 
@@ -604,4 +604,7 @@ public void register() {
         });
     }
 
+    private static String bossBarTitleToLegacy(final JsonElement title) {
+        return ViaRewind.getConfig().cacheBossBarTextConversion() ? ChatUtil.cachedJsonToLegacy(title) : ChatUtil.jsonToLegacy(title);
+    }
 }

common/src/main/java/com/viaversion/viarewind/utils/ChatUtil.java

@@ -26,6 +26,8 @@
 import com.viaversion.viaversion.protocols.v1_12_2to1_13.Protocol1_12_2To1_13;
 import com.viaversion.viaversion.rewriter.text.JsonNBTComponentRewriter;
 import com.viaversion.viaversion.util.ComponentUtil;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.logging.Level;
 import java.util.regex.Pattern;
 
@@ -41,6 +43,8 @@ protected void handleTranslate(JsonObject object, String translate) {
             }
         }
     };
+    private static final int LEGACY_CACHE_SIZE = 2048;
+    private static final Map<String, String> LEGACY_CACHE = new ConcurrentHashMap<>();
 
     public static String jsonToLegacy(String json) {
         if (json == null || json.equals("null") || json.isEmpty()) {
@@ -79,6 +83,25 @@ public static String jsonToLegacy(JsonElement component) {
         }
     }
 
+    /**
+     * Same as {@link #jsonToLegacy(JsonElement)}, but caches the result by the serialized component.
+     * The conversion does not depend on the connection, so the result is shared between all players.
+     * Once full, the cache is cleared as a whole.
+     */
+    public static String cachedJsonToLegacy(JsonElement component) {
+        // Use the serialized text as key, JsonPrimitive#equals treats e.g. 1 and 1.0 as equal
+        final String key = component.toString();
+        String legacy = LEGACY_CACHE.get(key);
+        if (legacy == null) {
+            legacy = jsonToLegacy(component);
+            if (LEGACY_CACHE.size() >= LEGACY_CACHE_SIZE) {
+                LEGACY_CACHE.clear();
+            }
+            LEGACY_CACHE.put(key, legacy);
+        }
+        return legacy;
+    }
+
     public static String removeUnusedColor(String legacy, char last) {
         if (legacy == null) return null;
         legacy = UNUSED_COLOR_PATTERN.matcher(legacy).replaceAll("$1$2");

common/src/main/resources/assets/viarewind/config.yml

@@ -41,4 +41,8 @@ offhand-command: '/offhand'
 emulate-levitation-effect: true
 #
 # If enabled, 1.8 players will handle the player combat packet added in 1.9 by showing the custom death message above the hotbar.
-handle-player-combat-packet: true
+handle-player-combat-packet: true
+#
+# Caches the text conversion of boss bar titles for 1.8 players.
+# Plugins often resend the same title to every online player, so this saves a lot of work. Disable if you see wrong boss bar titles.
+cache-bossbar-text-conversion: true