From 2f48f17a4e0f14fa160bb503eff5c0e0d9a0cdec Mon Sep 17 00:00:00 2001
From: Risto Lahtela <24460436+AuroraLS3@users.noreply.github.com>
Date: Sun, 14 Feb 2021 18:24:42 +0200
Subject: [PATCH] Cache placeholder result on non-server thread

Affects issues:
- Fixed #1756
---
 .../PlanPlaceholderExtension.java             | 38 ++++++++++++++++++-
 .../plan/placeholder/PlanPlaceholders.java    |  6 ---
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/Plan/bukkit/src/main/java/com/djrapitops/plan/addons/placeholderapi/PlanPlaceholderExtension.java b/Plan/bukkit/src/main/java/com/djrapitops/plan/addons/placeholderapi/PlanPlaceholderExtension.java
index 927c2dcf9..a793fa4cd 100644
--- a/Plan/bukkit/src/main/java/com/djrapitops/plan/addons/placeholderapi/PlanPlaceholderExtension.java
+++ b/Plan/bukkit/src/main/java/com/djrapitops/plan/addons/placeholderapi/PlanPlaceholderExtension.java
@@ -18,16 +18,23 @@ package com.djrapitops.plan.addons.placeholderapi;
 
 import com.djrapitops.plan.PlanSystem;
 import com.djrapitops.plan.placeholder.PlanPlaceholders;
+import com.djrapitops.plan.processing.Processing;
 import com.djrapitops.plan.utilities.logging.ErrorContext;
 import com.djrapitops.plan.utilities.logging.ErrorLogger;
 import com.djrapitops.plan.version.VersionChecker;
 import com.djrapitops.plugin.logging.L;
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
 import me.clip.placeholderapi.PlaceholderAPIPlugin;
 import me.clip.placeholderapi.expansion.PlaceholderExpansion;
 import org.bukkit.entity.Player;
 
 import java.util.Collections;
+import java.util.Objects;
+import java.util.Set;
 import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Placeholder expansion used to provide data from Plan on Bukkit.
@@ -40,14 +47,24 @@ public class PlanPlaceholderExtension extends PlaceholderExpansion {
     private final VersionChecker versionChecker;
     private final PlanPlaceholders placeholders;
 
+    private final Set<String> currentlyProcessing;
+    private final Processing processing;
+    private final Cache<String, String> cache;
+
     public PlanPlaceholderExtension(
             PlanPlaceholders placeholders,
             PlanSystem system,
             ErrorLogger errorLogger
     ) {
         this.placeholders = placeholders;
+        processing = system.getProcessing();
         this.versionChecker = system.getVersionChecker();
         this.errorLogger = errorLogger;
+
+        currentlyProcessing = Collections.newSetFromMap(new ConcurrentHashMap<>());
+        cache = Caffeine.newBuilder()
+                .expireAfterWrite(60, TimeUnit.SECONDS)
+                .build();
     }
 
     @Override
@@ -79,8 +96,12 @@ public class PlanPlaceholderExtension extends PlaceholderExpansion {
     public String onPlaceholderRequest(Player player, String params) {
         UUID uuid = player != null ? player.getUniqueId() : null;
         if ("Server thread".equalsIgnoreCase(Thread.currentThread().getName())) {
-            return "[placeholder replacement on server thread is not supported by Plan because it can crash the server!]";
+            return getCached(params, uuid);
         }
+        return getPlaceholderValue(params, uuid);
+    }
+
+    private String getPlaceholderValue(String params, UUID uuid) {
         try {
             String value = placeholders.onPlaceholderRequest(uuid, params, Collections.emptyList());
 
@@ -96,4 +117,19 @@ public class PlanPlaceholderExtension extends PlaceholderExpansion {
             return null;
         }
     }
+
+    private String getCached(String params, UUID uuid) {
+        String key = params + "-" + uuid;
+        String found = cache.getIfPresent(key);
+        if (found != null) return found;
+
+        if (!currentlyProcessing.contains(key)) {
+            currentlyProcessing.add(key);
+            processing.submitNonCritical(() -> {
+                cache.put(key, Objects.requireNonNull(getPlaceholderValue(params, uuid)));
+                currentlyProcessing.remove(key);
+            });
+        }
+        return null;
+    }
 }
diff --git a/Plan/common/src/main/java/com/djrapitops/plan/placeholder/PlanPlaceholders.java b/Plan/common/src/main/java/com/djrapitops/plan/placeholder/PlanPlaceholders.java
index be6d596de..33ebe6975 100644
--- a/Plan/common/src/main/java/com/djrapitops/plan/placeholder/PlanPlaceholders.java
+++ b/Plan/common/src/main/java/com/djrapitops/plan/placeholder/PlanPlaceholders.java
@@ -18,10 +18,7 @@ package com.djrapitops.plan.placeholder;
 
 import com.djrapitops.plan.delivery.domain.container.PlayerContainer;
 import com.djrapitops.plan.delivery.domain.keys.PlayerKeys;
-import com.djrapitops.plan.delivery.formatting.Formatters;
 import com.djrapitops.plan.gathering.cache.SessionCache;
-import com.djrapitops.plan.identification.ServerInfo;
-import com.djrapitops.plan.settings.config.PlanConfig;
 import com.djrapitops.plan.storage.database.DBSystem;
 import com.djrapitops.plan.storage.database.queries.containers.ContainerFetchQueries;
 
@@ -55,10 +52,7 @@ public final class PlanPlaceholders {
 
     @Inject
     public PlanPlaceholders(
-            PlanConfig config,
             DBSystem dbSystem,
-            ServerInfo serverInfo,
-            Formatters formatters,
             Set<Placeholders> placeholderRegistries
     ) {
         this.dbSystem = dbSystem;