From 6a439506b07605dd8566c86b672d3ee955715b51 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 16 Sep 2018 00:00:16 -0400
Subject: [PATCH] Fix major memory leaks in ExpiringMap

computeIfAbsent would leak as the entry
was never registered into the ttl map

This fixes that ,as well as redesigns cleaning to
not run on every manipulation, and instead to run clean
once per tick per expiring map.

diff --git a/src/main/java/net/minecraft/server/ExpiringMap.java b/src/main/java/net/minecraft/server/ExpiringMap.java
index 4006f5a69c..49021d29ee 100644
--- a/src/main/java/net/minecraft/server/ExpiringMap.java
+++ b/src/main/java/net/minecraft/server/ExpiringMap.java
@@ -6,25 +6,113 @@ import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
 import it.unimi.dsi.fastutil.longs.Long2LongMap.Entry;
 import it.unimi.dsi.fastutil.objects.ObjectIterator;
 import java.util.Map;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+import java.util.function.LongFunction;
 
 public class ExpiringMap<T> extends Long2ObjectOpenHashMap<T> {
     private final int a;
-    private final Long2LongMap b = new Long2LongLinkedOpenHashMap();
+    private final Long2LongMap ttl = new Long2LongLinkedOpenHashMap(); // Paper
 
     public ExpiringMap(int i, int j) {
         super(i);
         this.a = j;
     }
 
-    private void a(long i) {
-        long j = SystemUtils.b();
-        this.b.put(i, j);
-        ObjectIterator objectiterator = this.b.long2LongEntrySet().iterator();
+    // Paper start
+    private synchronized void setAccess(long i) { a(i); } // Paper - OBFHELPER
+    private synchronized void a(long i) {
+        long j = System.currentTimeMillis(); // Paper
+        this.ttl.put(i, j);
+        if (!registered) {
+            registered = true;
+            MinecraftServer.getServer().expiringMaps.add(this);
+        }
+    }
+
+    @Override
+    public T compute(long l, BiFunction<? super Long, ? super T, ? extends T> biFunction) {
+        setAccess(l);
+        return super.compute(l, biFunction);
+    }
+
+    @Override
+    public T putIfAbsent(long l, T t) {
+        setAccess(l);
+        return super.putIfAbsent(l, t);
+    }
+
+    @Override
+    public T computeIfPresent(long l, BiFunction<? super Long, ? super T, ? extends T> biFunction) {
+        setAccess(l);
+        return super.computeIfPresent(l, biFunction);
+    }
+
+    @Override
+    public T computeIfAbsent(long l, LongFunction<? extends T> longFunction) {
+        setAccess(l);
+        return super.computeIfAbsent(l, longFunction);
+    }
+
+    @Override
+    public boolean replace(long l, T t, T v1) {
+        setAccess(l);
+        return super.replace(l, t, v1);
+    }
+
+    @Override
+    public T replace(long l, T t) {
+        setAccess(l);
+        return super.replace(l, t);
+    }
+
+    @Override
+    public T putIfAbsent(Long aLong, T t) {
+        setAccess(aLong);
+        return super.putIfAbsent(aLong, t);
+    }
+
+    @Override
+    public boolean replace(Long aLong, T t, T v1) {
+        setAccess(aLong);
+        return super.replace(aLong, t, v1);
+    }
+
+    @Override
+    public T replace(Long aLong, T t) {
+        setAccess(aLong);
+        return super.replace(aLong, t);
+    }
+
+    @Override
+    public T computeIfAbsent(Long aLong, Function<? super Long, ? extends T> function) {
+        setAccess(aLong);
+        return super.computeIfAbsent(aLong, function);
+    }
+
+    @Override
+    public T computeIfPresent(Long aLong, BiFunction<? super Long, ? super T, ? extends T> biFunction) {
+        setAccess(aLong);
+        return super.computeIfPresent(aLong, biFunction);
+    }
+
+    @Override
+    public T compute(Long aLong, BiFunction<? super Long, ? super T, ? extends T> biFunction) {
+        setAccess(aLong);
+        return compute(aLong, biFunction);
+    }
+
+    private boolean registered = false;
+
+    // Break clean to its own method to be ticked
+    synchronized boolean clean() {
+        long now = System.currentTimeMillis();
+        ObjectIterator<Long2LongMap.Entry> objectiterator = this.ttl.long2LongEntrySet().iterator(); // Paper
 
         while(objectiterator.hasNext()) {
-            Entry entry = (Entry)objectiterator.next();
-            Object object = super.get(entry.getLongKey());
-            if (j - entry.getLongValue() <= (long)this.a) {
+            Long2LongMap.Entry entry = objectiterator.next(); // Paper
+            T object = super.get(entry.getLongKey()); // Paper
+            if (now - entry.getLongValue() <= (long)this.a) {
                 break;
             }
 
@@ -33,7 +121,18 @@ public class ExpiringMap<T> extends Long2ObjectOpenHashMap<T> {
                 objectiterator.remove();
             }
         }
-
+        if (this.ttl.size() != this.size()) {
+            MinecraftServer.LOGGER.error("WARNING: ExpiringMap desync - Memory leak risk!");
+            for (Entry<T> entry : this.long2ObjectEntrySet()) {
+                ttl.putIfAbsent(entry.getLongKey(), now);
+            }
+        }
+        if (isEmpty()) {
+            registered = false;
+            return true;
+        }
+        return false;
+        // Paper end
     }
 
     protected boolean a(T var1) {
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index 80e8b023cf..70a609efcc 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -155,6 +155,7 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
     public int autosavePeriod;
     public File bukkitDataPackFolder;
     public CommandDispatcher vanillaCommandDispatcher;
+    public List<ExpiringMap> expiringMaps = java.util.Collections.synchronizedList(new java.util.ArrayList<>()); // PAper
     // CraftBukkit end
     // Spigot start
     public static final int TPS = 20;
@@ -995,6 +996,7 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
         this.methodProfiler.e();
         org.spigotmc.WatchdogThread.tick(); // Spigot
         PaperLightingQueue.processQueue(startTime); // Paper
+        expiringMaps.removeIf(ExpiringMap::clean); // Paper
         this.slackActivityAccountant.tickEnded(l); // Spigot
         co.aikar.timings.TimingsManager.FULL_SERVER_TICK.stopTiming(); // Paper
     }
-- 
2.19.0