Try improving performance on legacy InteractEvent checks [SD-8155]

src/main/java/com/songoda/epicvouchers/EpicVouchers.java

@@ -30,6 +30,7 @@ import org.bukkit.configuration.ConfigurationSection;
 import org.bukkit.plugin.PluginManager;
 
 import java.io.File;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
@@ -166,13 +167,17 @@ public class EpicVouchers extends SongodaPlugin {
     }
 
     private void saveVouchers() {
+        Collection<Voucher> voucherList = voucherManager.getVouchers();
+
         for (String voucherName : vouchersConfig.getConfigurationSection("vouchers").getKeys(false)) {
-            if (voucherManager.getVouchers().stream().noneMatch(voucher -> voucher.getKey().equals(voucherName)))
+            if (voucherList.stream().noneMatch(voucher -> voucher.getKey().equals(voucherName))) {
                 vouchersConfig.set("vouchers." + voucherName, null);
             }
+        }
 
-        for (Voucher voucher : voucherManager.getVouchers()) {
+        for (Voucher voucher : voucherList) {
             String prefix = "vouchers." + voucher.getKey() + ".";
+
             vouchersConfig.set(prefix + "permission", voucher.getPermission());
             vouchersConfig.set(prefix + "material", voucher.getMaterial().name());
             vouchersConfig.set(prefix + "data", voucher.getData());
@@ -204,13 +209,16 @@ public class EpicVouchers extends SongodaPlugin {
             vouchersConfig.set(prefix + "effects.amplifier", voucher.getEffectAmplifier());
             vouchersConfig.set(prefix + "itemstack", voucher.getItemStack());
         }
+
         vouchersConfig.saveChanges();
     }
 
     @Override
     public void onConfigReload() {
         vouchersConfig.load();
+
         loadVouchersFromFile();
+
         this.setLocale(getConfig().getString("System.Language Mode"), true);
         this.locale.reloadMessages();
     }

src/main/java/com/songoda/epicvouchers/listeners/PlayerInteractListener.java

@@ -3,6 +3,7 @@ package com.songoda.epicvouchers.listeners;
 import com.songoda.core.nms.NmsManager;
 import com.songoda.core.nms.nbt.NBTItem;
 import com.songoda.epicvouchers.EpicVouchers;
+import com.songoda.epicvouchers.utils.CachedSet;
 import com.songoda.epicvouchers.voucher.Voucher;
 import org.bukkit.ChatColor;
 import org.bukkit.event.EventHandler;
@@ -15,44 +16,62 @@ import org.bukkit.inventory.meta.ItemMeta;
 public class PlayerInteractListener implements Listener {
     private final EpicVouchers instance;
 
+    private final CachedSet<ItemStack> checkedLegacyVouchers = new CachedSet<>(3 * 60);
+
     public PlayerInteractListener(EpicVouchers instance) {
         this.instance = instance;
     }
 
     @EventHandler
-    public void voucherListener(PlayerInteractEvent event) {
-        final ItemStack item = event.getItem();
-        if (item == null || (event.getAction() != Action.RIGHT_CLICK_AIR && event.getAction() != Action.RIGHT_CLICK_BLOCK))
-            return;
+    public void voucherListener(PlayerInteractEvent e) {
+        ItemStack item = e.getItem();
 
-        final NBTItem itemNbt = NmsManager.getNbt().of(item);
+        if (item != null && (e.getAction() == Action.RIGHT_CLICK_AIR || e.getAction() == Action.RIGHT_CLICK_BLOCK)) {
+            NBTItem itemNbt = NmsManager.getNbt().of(item);
+
+            boolean itemHasVoucher = itemNbt.has("epicvouchers:voucher");
+            String itemVoucherValue = itemNbt.getString("epicvouchers:voucher");
+
+            boolean legacyChecked = checkedLegacyVouchers.contains(item);
+
+            if (itemHasVoucher || !legacyChecked) {
+                boolean shouldBeLegacyCached = !itemHasVoucher;
 
                 for (Voucher voucher : instance.getVoucherManager().getVouchers()) {
-            final ItemStack voucherItem = voucher.toItemStack();
-
                     // Check voucher NBT.
-            if (itemNbt.has("epicvouchers:voucher") && itemNbt.getNBTObject("epicvouchers:voucher").asString().equals(voucher.getKey())) {
-                event.setCancelled(true);
-                voucher.redeemVoucher(event);
-                continue;
+                    if (itemHasVoucher && itemVoucherValue.equals(voucher.getKey())) {
+                        e.setCancelled(true);
+                        voucher.redeemVoucher(e);
+                        break;
                     }
 
+                    // TODO: eventually make the legacy check configurable as a lot of players (and vouchers) quickly cause lag
                     // Legacy crap.
                     // does the item they're holding match this voucher?
+                    ItemStack voucherItem = voucher.toItemStack();
 
-            if (voucherItem != null && !voucherItem.isSimilar(item)) continue;
-            else if (item.getType() != voucher.getMaterial() || item.getDurability() != voucher.getData()) continue;
-            else {
+                    if ((voucherItem == null || voucherItem.isSimilar(item)) &&
+                            item.getType() == voucher.getMaterial() &&
+                            item.getDurability() == voucher.getData()) {
                         // material matches - verify the name + lore
-                final ItemMeta meta = item.getItemMeta();
-                if (meta == null || !meta.hasDisplayName()
-                        || !ChatColor.stripColor(meta.getDisplayName()).equals(ChatColor.stripColor(voucher.getName(true)))
-                        || (meta.hasLore() && !meta.getLore().equals(voucher.getLore(true))))
-                    continue;
+                        ItemMeta meta = item.getItemMeta();
+
+                        if (meta != null && meta.hasDisplayName()
+                                && ChatColor.stripColor(meta.getDisplayName()).equals(ChatColor.stripColor(voucher.getName(true)))
+                                && (!meta.hasLore() || meta.getLore().equals(voucher.getLore(true)))) {
+                            e.setCancelled(true);
+                            voucher.redeemVoucher(e);
+
+                            shouldBeLegacyCached = false;
+                            break;
+                        }
+                    }
                 }
 
-            event.setCancelled(true);
-            voucher.redeemVoucher(event);
+                if (shouldBeLegacyCached) {
+                    this.checkedLegacyVouchers.add(item);
+                }
+            }
         }
     }
 }

src/main/java/com/songoda/epicvouchers/utils/CachedSet.java

@@ -0,0 +1,40 @@
+package com.songoda.epicvouchers.utils;
+
+import java.util.Map;
+import java.util.WeakHashMap;
+
+public class CachedSet<K> {
+    private final Map<K, Long> cache = new WeakHashMap<>();
+    private final int ttl;
+
+    private long lastClear = System.currentTimeMillis();
+
+    /**
+     * @param ttl Time-To-Live in seconds
+     */
+    public CachedSet(int ttl) {
+        this.ttl = ttl * 1000;
+    }
+
+    public void add(K obj) {
+        this.cache.put(obj, System.currentTimeMillis());
+    }
+
+    public boolean contains(K obj) {
+        if (shouldClear()) {
+            clearStale();
+        }
+
+        return this.cache.computeIfPresent(obj, (k, aLong) -> System.currentTimeMillis()) != null;
+    }
+
+    public void clearStale() {
+        this.cache.entrySet().removeIf(entry -> System.currentTimeMillis() - entry.getValue() >= ttl);
+
+        this.lastClear = System.currentTimeMillis();
+    }
+
+    private boolean shouldClear() {
+        return !this.cache.isEmpty() && System.currentTimeMillis() - lastClear > ttl;
+    }
+}