Placeholders - Add timeout for placeholders to return value, causing …

…TAB to freeze
NEZNAMY · Dec 23, 2022 · 37caed3 · 37caed3
1 parent 27fe9df
commit 37caed3
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Showing 5 changed files with 55 additions and 18 deletions.
diff --git a/api/src/main/java/me/neznamy/tab/api/TabConstants.java b/api/src/main/java/me/neznamy/tab/api/TabConstants.java
@@ -335,8 +335,23 @@ public static class Placeholder {
         public static final String VAULT_SUFFIX = "%vault-suffix%";
         public static final String HEALTH = "%health%";
 
+        /**
+         * Minimum refresh interval of a placeholder in milliseconds, used to set refresh interval of the main task
+         */
         public static final int MINIMUM_REFRESH_INTERVAL = 50;
 
+        /**
+         * Timeout in milliseconds for a placeholder to return value
+         * to prevent SQL tasks by PlaceholderAPI placeholders from freezing TAB
+         */
+        public static final int PLACEHOLDER_RETRIEVE_TIMEOUT = 50;
+
+        /**
+         * Internal constant used to detect if placeholder threw an error.
+         * If so, placeholder's last known value is displayed instead.
+         */
+        public static final String ERROR_VALUE = "ERROR";
+
 
         public static String condition(String name) {
             return "%condition:" + name + "%";

diff --git a/shared/src/main/java/me/neznamy/tab/shared/placeholders/PlayerPlaceholderImpl.java b/shared/src/main/java/me/neznamy/tab/shared/placeholders/PlayerPlaceholderImpl.java
@@ -1,24 +1,22 @@
 package me.neznamy.tab.shared.placeholders;
 
-import java.util.*;
-import java.util.function.Function;
-
+import me.neznamy.tab.api.TabConstants;
 import me.neznamy.tab.api.TabFeature;
 import me.neznamy.tab.api.TabPlayer;
 import me.neznamy.tab.api.placeholder.PlayerPlaceholder;
 import me.neznamy.tab.shared.TAB;
 
+import java.util.Set;
+import java.util.WeakHashMap;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.function.Function;
+
 /**
  * Implementation of the PlayerPlaceholder interface
  */
 public class PlayerPlaceholderImpl extends TabPlaceholder implements PlayerPlaceholder {
 
-    /**
-     * Internal constant used to detect if placeholder threw an error.
-     * If so, placeholder's last known value is displayed.
-     */
-    private final String ERROR_VALUE = "ERROR";
-
     /** Placeholder function returning fresh output on request */
     private final Function<TabPlayer, Object> function;
 
@@ -59,8 +57,8 @@ public boolean update(TabPlayer p) {
         if (identifier.equals(newValue) && !lastValues.containsKey(p)) {
             lastValues.put(p, identifier);
         }
-        if (!lastValues.containsKey(p) || (!ERROR_VALUE.equals(newValue) && !identifier.equals(newValue) && !lastValues.get(p).equals(newValue))) {
-            lastValues.put(p, ERROR_VALUE.equals(newValue) ? identifier : newValue);
+        if (!lastValues.containsKey(p) || (!TabConstants.Placeholder.ERROR_VALUE.equals(newValue) && !identifier.equals(newValue) && !lastValues.get(p).equals(newValue))) {
+            lastValues.put(p, TabConstants.Placeholder.ERROR_VALUE.equals(newValue) ? identifier : newValue);
             updateParents(p);
             if (TAB.getInstance().getPlaceholderManager().getTabExpansion() != null)
                 TAB.getInstance().getPlaceholderManager().getTabExpansion().setPlaceholderValue(p, identifier, newValue);
@@ -127,10 +125,14 @@ public String getLastValue(TabPlayer p) {
     @Override
     public Object request(TabPlayer p) {
         try {
-            return function.apply(p);
+            return placeholderFutureThreadPool.submit(() -> function.apply(p)).get(
+                    TabConstants.Placeholder.PLACEHOLDER_RETRIEVE_TIMEOUT, TimeUnit.MILLISECONDS);
+        } catch (TimeoutException e) {
+            TAB.getInstance().getErrorManager().criticalError("Placeholder " + identifier + " took longer than " +
+                    TabConstants.Placeholder.PLACEHOLDER_RETRIEVE_TIMEOUT + "ms to retrieve value for player " + p.getName() + ", aborting.", null);
         } catch (Throwable t) {
             TAB.getInstance().getErrorManager().placeholderError("Player placeholder " + identifier + " generated an error when setting for player " + p.getName(), t);
-            return ERROR_VALUE;
         }
+        return TabConstants.Placeholder.ERROR_VALUE;
     }
 }
diff --git a/shared/src/main/java/me/neznamy/tab/shared/placeholders/RelationalPlaceholderImpl.java b/shared/src/main/java/me/neznamy/tab/shared/placeholders/RelationalPlaceholderImpl.java
@@ -2,8 +2,11 @@
 
 import java.util.Set;
 import java.util.WeakHashMap;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 import java.util.function.BiFunction;
 
+import me.neznamy.tab.api.TabConstants;
 import me.neznamy.tab.api.TabFeature;
 import me.neznamy.tab.api.TabPlayer;
 import me.neznamy.tab.api.chat.EnumChatFormat;
@@ -116,10 +119,14 @@ public void updateFromNested(TabPlayer player) {
     @Override
     public Object request(TabPlayer viewer, TabPlayer target) {
         try {
-            return function.apply(viewer, target);
+            return placeholderFutureThreadPool.submit(() -> function.apply(viewer, target)).get(
+                    TabConstants.Placeholder.PLACEHOLDER_RETRIEVE_TIMEOUT, TimeUnit.MILLISECONDS);
+        } catch (TimeoutException e) {
+            TAB.getInstance().getErrorManager().criticalError("Placeholder " + identifier + " took longer than " +
+                    TabConstants.Placeholder.PLACEHOLDER_RETRIEVE_TIMEOUT + "ms to retrieve value for viewer " + viewer.getName() + " and target " + target.getName() + ", aborting.", null);
         } catch (Throwable t) {
             TAB.getInstance().getErrorManager().placeholderError("Relational placeholder " + identifier + " generated an error when setting for players " + viewer.getName() + " and " + target.getName(), t);
-            return "ERROR";
         }
+        return TabConstants.Placeholder.ERROR_VALUE;
     }
 }
diff --git a/shared/src/main/java/me/neznamy/tab/shared/placeholders/ServerPlaceholderImpl.java b/shared/src/main/java/me/neznamy/tab/shared/placeholders/ServerPlaceholderImpl.java
@@ -1,8 +1,11 @@
 package me.neznamy.tab.shared.placeholders;
 
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 import java.util.function.Supplier;
 
+import me.neznamy.tab.api.TabConstants;
 import me.neznamy.tab.api.TabFeature;
 import me.neznamy.tab.api.TabPlayer;
 import me.neznamy.tab.api.placeholder.ServerPlaceholder;
@@ -50,7 +53,7 @@ public boolean update() {
         if (identifier.equals(newValue) && lastValue == null) {
             lastValue = identifier;
         }
-        if (!"ERROR".equals(newValue) && !identifier.equals(newValue) && (lastValue == null || !lastValue.equals(newValue))) {
+        if (!TabConstants.Placeholder.ERROR_VALUE.equals(newValue) && !identifier.equals(newValue) && (lastValue == null || !lastValue.equals(newValue))) {
             lastValue = newValue;
             for (TabPlayer player : TAB.getInstance().getOnlinePlayers()) {
                 updateParents(player);
@@ -113,10 +116,14 @@ public String getLastValue() {
     @Override
     public Object request() {
         try {
-            return supplier.get();
+            return placeholderFutureThreadPool.submit(supplier::get).get(
+                    TabConstants.Placeholder.PLACEHOLDER_RETRIEVE_TIMEOUT, TimeUnit.MILLISECONDS);
+        } catch (TimeoutException e) {
+            TAB.getInstance().getErrorManager().criticalError("Placeholder " + identifier + " took longer than " +
+                    TabConstants.Placeholder.PLACEHOLDER_RETRIEVE_TIMEOUT + "ms to retrieve value, aborting.", null);
         } catch (Throwable t) {
             TAB.getInstance().getErrorManager().placeholderError("Server placeholder " + identifier + " generated an error", t);
-            return "ERROR";
         }
+        return TabConstants.Placeholder.ERROR_VALUE;
     }
 }
diff --git a/shared/src/main/java/me/neznamy/tab/shared/placeholders/TabPlaceholder.java b/shared/src/main/java/me/neznamy/tab/shared/placeholders/TabPlaceholder.java
@@ -1,5 +1,6 @@
 package me.neznamy.tab.shared.placeholders;
 
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import me.neznamy.tab.api.TabAPI;
 import me.neznamy.tab.api.TabConstants;
 import me.neznamy.tab.api.TabPlayer;
@@ -8,12 +9,17 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 /**
  * General collection of variables and functions shared between all placeholder types
  */
 public abstract class TabPlaceholder implements Placeholder {
 
+    /** Thread pool for submitting placeholder requests with a timeout */
+    protected static ExecutorService placeholderFutureThreadPool = Executors.newCachedThreadPool(new ThreadFactoryBuilder().setNameFormat("TAB Placeholder retrieving thread %d").build());
+
     /** Refresh interval of the placeholder */
     private final int refresh;