From 2f22a5cc15f69a04dd205f4a24c8cf280f0f4a57 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 3 Sep 2018 22:18:38 -0400
Subject: [PATCH] Fix concurrency issues in DataFixers

We are seeing issues with DataFixers being not thread safe in async chunks
and even in some spigot packet sending code.

There are a few more global objects that are mutated that need to
be synchronized to be safe for use over multiple threads.

There may be more cases, but these are extremely obvious ones.

diff --git a/src/main/java/com/mojang/datafixers/DataFixerUpper.java b/src/main/java/com/mojang/datafixers/DataFixerUpper.java
index fb2c380f8a..9299cbbdbd 100644
--- a/src/main/java/com/mojang/datafixers/DataFixerUpper.java
+++ b/src/main/java/com/mojang/datafixers/DataFixerUpper.java
@@ -125,7 +125,7 @@ public class DataFixerUpper implements DataFixer {
         final int expandedDataVersion = DataFixUtils.makeKey(dataVersion);
 
         final long key = (long) expandedVersion << 32 | expandedDataVersion;
-        if (!rules.containsKey(key)) {
+        rules.computeIfAbsent(key, k -> { // Paper
             final List<TypeRewriteRule> rules = Lists.newArrayList();
             for (final DataFix fix : globalList) {
                 final int fixVersion = fix.getVersionKey();
@@ -137,8 +137,8 @@ public class DataFixerUpper implements DataFixer {
                     rules.add(fixRule);
                 }
             }
-            this.rules.put(key, TypeRewriteRule.seq(rules));
-        }
+            return TypeRewriteRule.seq(rules); // Paper
+        }); // Paper
         return rules.get(key);
     }
 
diff --git a/src/main/java/com/mojang/datafixers/schemas/Schema.java b/src/main/java/com/mojang/datafixers/schemas/Schema.java
index 7c67d989e0..45f3ef5957 100644
--- a/src/main/java/com/mojang/datafixers/schemas/Schema.java
+++ b/src/main/java/com/mojang/datafixers/schemas/Schema.java
@@ -20,8 +20,8 @@ import java.util.function.Function;
 import java.util.function.Supplier;
 
 public class Schema {
-    protected final Object2IntMap<String> RECURSIVE_TYPES = new Object2IntOpenHashMap<>();
-    private final Map<String, Supplier<TypeTemplate>> TYPE_TEMPLATES = Maps.newHashMap();
+    protected final Object2IntMap<String> RECURSIVE_TYPES = it.unimi.dsi.fastutil.objects.Object2IntMaps.synchronize(new Object2IntOpenHashMap<>()); // Paper
+    private final Map<String, Supplier<TypeTemplate>> TYPE_TEMPLATES = Maps.newConcurrentMap(); // Paper
     private final Map<String, Type<?>> TYPES;
     private final int versionKey;
     private final String name;
@@ -37,17 +37,19 @@ public class Schema {
     }
 
     protected Map<String, Type<?>> buildTypes() {
-        final Map<String, Type<?>> types = Maps.newHashMap();
+        final Map<String, Type<?>> types = Maps.newConcurrentMap(); // Paper
 
         final List<TypeTemplate> templates = Lists.newArrayList();
 
+        synchronized (RECURSIVE_TYPES) { // Paper
         for (final Object2IntMap.Entry<String> entry : RECURSIVE_TYPES.object2IntEntrySet()) {
             templates.add(DSL.check(entry.getKey(), entry.getIntValue(), getTemplate(entry.getKey())));
-        }
+        } } // Paper
 
         final TypeTemplate choice = templates.stream().reduce(DSL::or).get();
         final TypeFamily family = new RecursiveTypeFamily(name, choice);
 
+        synchronized (TYPE_TEMPLATES) { // Paper
         for (final String name : TYPE_TEMPLATES.keySet()) {
             final Type<?> type;
             if (RECURSIVE_TYPES.containsKey(name)) {
@@ -56,7 +58,7 @@ public class Schema {
                 type = getTemplate(name).apply(family).apply(-1);
             }
             types.put(name, type);
-        }
+        } } // Paper
         return types;
     }
 
@@ -89,9 +91,10 @@ public class Schema {
     }
 
     public TypeTemplate id(final String name) {
+        synchronized (RECURSIVE_TYPES) { // Paper
         if (RECURSIVE_TYPES.containsKey(name)) {
-            return DSL.id(RECURSIVE_TYPES.get(name));
-        }
+            return DSL.id(RECURSIVE_TYPES.getInt(name)); // Paper
+        } } // Paper
         return getTemplate(name);
     }
 
@@ -138,9 +141,10 @@ public class Schema {
     public void registerType(final boolean recursive, final DSL.TypeReference type, final Supplier<TypeTemplate> template) {
         TYPE_TEMPLATES.put(type.typeName(), template);
         // TODO: calculate recursiveness instead of hardcoding
+        synchronized (RECURSIVE_TYPES) { // Paper
         if (recursive && !RECURSIVE_TYPES.containsKey(type.typeName())) {
             RECURSIVE_TYPES.put(type.typeName(), RECURSIVE_TYPES.size());
-        }
+        } } // Paper
     }
 
     public int getVersionKey() {
diff --git a/src/main/java/com/mojang/datafixers/types/families/RecursiveTypeFamily.java b/src/main/java/com/mojang/datafixers/types/families/RecursiveTypeFamily.java
index 4a1f906837..93c2f565fd 100644
--- a/src/main/java/com/mojang/datafixers/types/families/RecursiveTypeFamily.java
+++ b/src/main/java/com/mojang/datafixers/types/families/RecursiveTypeFamily.java
@@ -32,7 +32,7 @@ public final class RecursiveTypeFamily implements TypeFamily {
     private final TypeTemplate template;
     private final int size;
 
-    private final Int2ObjectMap<RecursivePoint.RecursivePointType<?>> types = new Int2ObjectOpenHashMap<>();
+    private final Int2ObjectMap<RecursivePoint.RecursivePointType<?>> types = it.unimi.dsi.fastutil.ints.Int2ObjectMaps.synchronize(new Int2ObjectOpenHashMap<>()); // Paper
     private final int hashCode;
 
     public RecursiveTypeFamily(final String name, final TypeTemplate template) {
-- 
2.18.0