Paper/patches/server/0774-Custom-table-implementation-for-blockstate-state-loo.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Thu, 11 Mar 2021 20:05:44 -0800
Subject: [PATCH] Custom table implementation for blockstate state lookups

Testing some redstone intensive machines showed to bring about a 10%
improvement.

diff --git a/src/main/java/io/papermc/paper/util/table/ZeroCollidingReferenceStateTable.java b/src/main/java/io/papermc/paper/util/table/ZeroCollidingReferenceStateTable.java
new file mode 100644
index 0000000000000000000000000000000000000000..57d0cd3ad6f972e986c72a57f1a6e36003f190c2
--- /dev/null
+++ b/src/main/java/io/papermc/paper/util/table/ZeroCollidingReferenceStateTable.java
@@ -0,0 +1,160 @@
+package io.papermc.paper.util.table;
+
+import com.google.common.collect.Table;
+import net.minecraft.world.level.block.state.StateHolder;
+import net.minecraft.world.level.block.state.properties.Property;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+public final class ZeroCollidingReferenceStateTable {
+
+    // upper 32 bits: starting index
+    // lower 32 bits: bitset for contained ids
+    protected final long[] this_index_table;
+    protected final Comparable<?>[] this_table;
+    protected final StateHolder<?, ?> this_state;
+
+    protected long[] index_table;
+    protected StateHolder<?, ?>[][] value_table;
+
+    public ZeroCollidingReferenceStateTable(final StateHolder<?, ?> state, final Map<Property<?>, Comparable<?>> this_map) {
+        this.this_state = state;
+        this.this_index_table = this.create_table(this_map.keySet());
+
+        int max_id = -1;
+        for (final Property<?> property : this_map.keySet()) {
+            final int id = lookup_vindex(property, this.this_index_table);
+            if (id > max_id) {
+                max_id = id;
+            }
+        }
+
+        this.this_table = new Comparable[max_id + 1];
+        for (final Map.Entry<Property<?>, Comparable<?>> entry : this_map.entrySet()) {
+            this.this_table[lookup_vindex(entry.getKey(), this.this_index_table)] = entry.getValue();
+        }
+    }
+
+    public void loadInTable(final Table<Property<?>, Comparable<?>, StateHolder<?, ?>> table,
+                            final Map<Property<?>, Comparable<?>> this_map) {
+        final Set<Property<?>> combined = new HashSet<>(table.rowKeySet());
+        combined.addAll(this_map.keySet());
+
+        this.index_table = this.create_table(combined);
+
+        int max_id = -1;
+        for (final Property<?> property : combined) {
+            final int id = lookup_vindex(property, this.index_table);
+            if (id > max_id) {
+                max_id = id;
+            }
+        }
+
+        this.value_table = new StateHolder[max_id + 1][];
+
+        final Map<Property<?>, Map<Comparable<?>, StateHolder<?, ?>>> map = table.rowMap();
+        for (final Property<?> property : map.keySet()) {
+            final Map<Comparable<?>, StateHolder<?, ?>> propertyMap = map.get(property);
+
+            final int id = lookup_vindex(property, this.index_table);
+            final StateHolder<?, ?>[] states = this.value_table[id] = new StateHolder[property.getPossibleValues().size()];
+
+            for (final Map.Entry<Comparable<?>, StateHolder<?, ?>> entry : propertyMap.entrySet()) {
+                if (entry.getValue() == null) {
+                    // TODO what
+                    continue;
+                }
+
+                states[((Property)property).getIdFor(entry.getKey())] = entry.getValue();
+            }
+        }
+
+
+        for (final Map.Entry<Property<?>, Comparable<?>> entry : this_map.entrySet()) {
+            final Property<?> property = entry.getKey();
+            final int index = lookup_vindex(property, this.index_table);
+
+            if (this.value_table[index] == null) {
+                this.value_table[index] = new StateHolder[property.getPossibleValues().size()];
+            }
+
+            this.value_table[index][((Property)property).getIdFor(entry.getValue())] = this.this_state;
+        }
+    }
+
+
+    protected long[] create_table(final Collection<Property<?>> collection) {
+        int max_id = -1;
+        for (final Property<?> property : collection) {
+            final int id = property.getId();
+            if (id > max_id) {
+                max_id = id;
+            }
+        }
+
+        final long[] ret = new long[((max_id + 1) + 31) >>> 5]; // ceil((max_id + 1) / 32)
+
+        for (final Property<?> property : collection) {
+            final int id = property.getId();
+
+            ret[id >>> 5] |= (1L << (id & 31));
+        }
+
+        int total = 0;
+        for (int i = 1, len = ret.length; i < len; ++i) {
+            ret[i] |= (long)(total += Long.bitCount(ret[i - 1] & 0xFFFFFFFFL)) << 32;
+        }
+
+        return ret;
+    }
+
+    public Comparable<?> get(final Property<?> state) {
+        final Comparable<?>[] table = this.this_table;
+        final int index = lookup_vindex(state, this.this_index_table);
+
+        if (index < 0 || index >= table.length) {
+            return null;
+        }
+        return table[index];
+    }
+
+    public StateHolder<?, ?> get(final Property<?> property, final Comparable<?> with) {
+        final int withId = ((Property)property).getIdFor(with);
+        if (withId < 0) {
+            return null;
+        }
+
+        final int index = lookup_vindex(property, this.index_table);
+        final StateHolder<?, ?>[][] table = this.value_table;
+        if (index < 0 || index >= table.length) {
+            return null;
+        }
+
+        final StateHolder<?, ?>[] values = table[index];
+
+        if (withId >= values.length) {
+            return null;
+        }
+
+        return values[withId];
+    }
+
+    protected static int lookup_vindex(final Property<?> property, final long[] index_table) {
+        final int id = property.getId();
+        final long bitset_mask = (1L << (id & 31));
+        final long lower_mask = bitset_mask - 1;
+        final int index = id >>> 5;
+        if (index >= index_table.length) {
+            return -1;
+        }
+        final long index_value = index_table[index];
+        final long contains_check = ((index_value & bitset_mask) - 1) >> (Long.SIZE - 1); // -1L if doesn't contain
+
+        // index = total bits set in lower table values (upper 32 bits of index_value) plus total bits set in lower indices below id
+        // contains_check is 0 if the bitset had id set, else it's -1: so index is unaffected if contains_check == 0,
+        // otherwise it comes out as -1.
+        return (int)(((index_value >>> 32) + Long.bitCount(index_value & lower_mask)) | contains_check);
+    }
+}
diff --git a/src/main/java/net/minecraft/world/level/block/state/StateHolder.java b/src/main/java/net/minecraft/world/level/block/state/StateHolder.java
index baf1cb77eb170a44d821eae572d059f18ea46d7e..11c05776c051ba6a7e8416fd8591babafda35a80 100644
--- a/src/main/java/net/minecraft/world/level/block/state/StateHolder.java
+++ b/src/main/java/net/minecraft/world/level/block/state/StateHolder.java
@@ -40,11 +40,13 @@ public abstract class StateHolder<O, S> {
     private final ImmutableMap<Property<?>, Comparable<?>> values;
     private Table<Property<?>, Comparable<?>, S> neighbours;
     protected final MapCodec<S> propertiesCodec;
+    protected final io.papermc.paper.util.table.ZeroCollidingReferenceStateTable optimisedTable; // Paper - optimise state lookup
 
     protected StateHolder(O owner, ImmutableMap<Property<?>, Comparable<?>> entries, MapCodec<S> codec) {
         this.owner = owner;
         this.values = entries;
         this.propertiesCodec = codec;
+        this.optimisedTable = new io.papermc.paper.util.table.ZeroCollidingReferenceStateTable(this, entries); // Paper - optimise state lookup
     }
 
     public <T extends Comparable<T>> S cycle(Property<T> property) {
@@ -85,11 +87,11 @@ public abstract class StateHolder<O, S> {
     }
 
     public <T extends Comparable<T>> boolean hasProperty(Property<T> property) {
-        return this.values.containsKey(property);
+        return this.optimisedTable.get(property) != null; // Paper - optimise state lookup
     }
 
     public <T extends Comparable<T>> T getValue(Property<T> property) {
-        Comparable<?> comparable = this.values.get(property);
+        Comparable<?> comparable = this.optimisedTable.get(property); // Paper - optimise state lookup
         if (comparable == null) {
             throw new IllegalArgumentException("Cannot get property " + property + " as it does not exist in " + this.owner);
         } else {
@@ -98,24 +100,18 @@ public abstract class StateHolder<O, S> {
     }
 
     public <T extends Comparable<T>> Optional<T> getOptionalValue(Property<T> property) {
-        Comparable<?> comparable = this.values.get(property);
+        Comparable<?> comparable = this.optimisedTable.get(property); // Paper - optimise state lookup
         return comparable == null ? Optional.empty() : Optional.of(property.getValueClass().cast(comparable));
     }
 
     public <T extends Comparable<T>, V extends T> S setValue(Property<T> property, V value) {
-        Comparable<?> comparable = this.values.get(property);
-        if (comparable == null) {
-            throw new IllegalArgumentException("Cannot set property " + property + " as it does not exist in " + this.owner);
-        } else if (comparable == value) {
-            return (S)this;
-        } else {
-            S object = this.neighbours.get(property, value);
-            if (object == null) {
-                throw new IllegalArgumentException("Cannot set property " + property + " to " + value + " on " + this.owner + ", it is not an allowed value");
-            } else {
-                return object;
-            }
+        // Paper start - optimise state lookup
+        final S ret = (S)this.optimisedTable.get(property, value);
+        if (ret == null) {
+            throw new IllegalArgumentException("Cannot set property " + property + " to " + value + " on " + this.owner + ", it is not an allowed value");
         }
+        return ret;
+        // Paper end - optimise state lookup
     }
 
     public void populateNeighbours(Map<Map<Property<?>, Comparable<?>>, S> states) {
@@ -134,7 +130,7 @@ public abstract class StateHolder<O, S> {
                 }
             }
 
-            this.neighbours = (Table<Property<?>, Comparable<?>, S>)(table.isEmpty() ? table : ArrayTable.create(table));
+            this.neighbours = (Table<Property<?>, Comparable<?>, S>)(table.isEmpty() ? table : ArrayTable.create(table)); this.optimisedTable.loadInTable((Table)this.neighbours, this.values); // Paper - optimise state lookup
         }
     }
 
diff --git a/src/main/java/net/minecraft/world/level/block/state/properties/BooleanProperty.java b/src/main/java/net/minecraft/world/level/block/state/properties/BooleanProperty.java
index ff1a0d125edd2ea10c870cbb62ae9aa23644b6dc..233215280f8494dbc33a2fd0b14e37e59f1cb643 100644
--- a/src/main/java/net/minecraft/world/level/block/state/properties/BooleanProperty.java
+++ b/src/main/java/net/minecraft/world/level/block/state/properties/BooleanProperty.java
@@ -7,6 +7,13 @@ import java.util.Optional;
 public class BooleanProperty extends Property<Boolean> {
     private final ImmutableSet<Boolean> values = ImmutableSet.of(true, false);
 
+    // Paper start - optimise iblockdata state lookup
+    @Override
+    public final int getIdFor(final Boolean value) {
+        return value.booleanValue() ? 1 : 0;
+    }
+    // Paper end - optimise iblockdata state lookup
+
     protected BooleanProperty(String name) {
         super(name, Boolean.class);
     }
diff --git a/src/main/java/net/minecraft/world/level/block/state/properties/EnumProperty.java b/src/main/java/net/minecraft/world/level/block/state/properties/EnumProperty.java
index bcf8b24e9f9e9870c1a1d27c721a6a433305d55a..6b05e766162b2cf8b499e5b0effb2cd15e57bea3 100644
--- a/src/main/java/net/minecraft/world/level/block/state/properties/EnumProperty.java
+++ b/src/main/java/net/minecraft/world/level/block/state/properties/EnumProperty.java
@@ -17,6 +17,15 @@ public class EnumProperty<T extends Enum<T> & StringRepresentable> extends Prope
     private final ImmutableSet<T> values;
     private final Map<String, T> names = Maps.newHashMap();
 
+    // Paper start - optimise iblockdata state lookup
+    private int[] idLookupTable;
+
+    @Override
+    public final int getIdFor(final T value) {
+        return this.idLookupTable[value.ordinal()];
+    }
+    // Paper end - optimise iblockdata state lookup
+
     protected EnumProperty(String name, Class<T> type, Collection<T> values) {
         super(name, type);
         this.values = ImmutableSet.copyOf(values);
@@ -31,6 +40,14 @@ public class EnumProperty<T extends Enum<T> & StringRepresentable> extends Prope
             this.names.put(string, enum_);
         }
 
+        // Paper start - optimise iblockdata state lookup
+        int id = 0;
+        this.idLookupTable = new int[type.getEnumConstants().length];
+        java.util.Arrays.fill(this.idLookupTable, -1);
+        for (final T value : this.getPossibleValues()) {
+            this.idLookupTable[value.ordinal()] = id++;
+        }
+        // Paper end - optimise iblockdata state lookup
     }
 
     @Override
diff --git a/src/main/java/net/minecraft/world/level/block/state/properties/IntegerProperty.java b/src/main/java/net/minecraft/world/level/block/state/properties/IntegerProperty.java
index 72f508321ebffcca31240fbdd068b4d185454cbc..d16156f8a4a2507e114dc651fd0af9cdffb3c8e0 100644
--- a/src/main/java/net/minecraft/world/level/block/state/properties/IntegerProperty.java
+++ b/src/main/java/net/minecraft/world/level/block/state/properties/IntegerProperty.java
@@ -13,6 +13,16 @@ public class IntegerProperty extends Property<Integer> {
     public final int min;
     public final int max;
 
+    // Paper start - optimise iblockdata state lookup
+    @Override
+    public final int getIdFor(final Integer value) {
+        final int val = value.intValue();
+        final int ret = val - this.min;
+
+        return ret | ((this.max - ret) >> 31);
+    }
+    // Paper end - optimise iblockdata state lookup
+
     protected IntegerProperty(String name, int min, int max) {
         super(name, Integer.class);
         this.min = min;
diff --git a/src/main/java/net/minecraft/world/level/block/state/properties/Property.java b/src/main/java/net/minecraft/world/level/block/state/properties/Property.java
index 81b43e0b0146729a8a1c6ade82634c86cde67857..44118dbd1ed212a0911f1244e7fea78cee275aad 100644
--- a/src/main/java/net/minecraft/world/level/block/state/properties/Property.java
+++ b/src/main/java/net/minecraft/world/level/block/state/properties/Property.java
@@ -20,6 +20,17 @@ public abstract class Property<T extends Comparable<T>> {
     }, this::getName);
     private final Codec<Property.Value<T>> valueCodec = this.codec.xmap(this::value, Property.Value::value);
 
+    // Paper start - optimise iblockdata state lookup
+    private static final java.util.concurrent.atomic.AtomicInteger ID_GENERATOR = new java.util.concurrent.atomic.AtomicInteger();
+    private final int id = ID_GENERATOR.getAndIncrement();
+
+    public final int getId() {
+        return this.id;
+    }
+
+    public abstract int getIdFor(final T value);
+    // Paper end - optimise state lookup
+
     protected Property(String name, Class<T> type) {
         this.clazz = type;
         this.name = name;