Yatopia/patches/Airplane/patches/server/0023-Improve-fluid-directio...

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Paul Sauve <paul@technove.co>
Date: Wed, 14 Apr 2021 22:58:15 -0500
Subject: [PATCH] Improve fluid direction caching
Implements a custom cache that better fits the needs of fluids
calculating whether a direction can be moved in or something. There's a
big javadoc on the FluidDirectionCache with some more information.
diff --git a/src/main/java/gg/airplane/structs/FluidDirectionCache.java b/src/main/java/gg/airplane/structs/FluidDirectionCache.java
new file mode 100644
index 0000000000000000000000000000000000000000..11279fb136bbaf3e51d9b080a9e283d8ff0cbb47
--- /dev/null
+++ b/src/main/java/gg/airplane/structs/FluidDirectionCache.java
@@ -0,0 +1,142 @@
+package gg.airplane.structs;
+
+import it.unimi.dsi.fastutil.HashCommon;
+
+/**
+ * This is a replacement for the cache used in FluidTypeFlowing.
+ * The requirements for the previous cache were:
+ * - Store 200 entries
+ * - Look for the flag in the cache
+ * - If it exists, move to front of cache
+ * - If it doesn't exist, remove last entry in cache and insert in front
+ *
+ * This class accomplishes something similar, however has a few different
+ * requirements put into place to make this more optimize:
+ *
+ * - maxDistance is the most amount of entries to be checked, instead
+ * of having to check the entire list.
+ * - In combination with that, entries are all tracked by age and how
+ * frequently they're used. This enables us to remove old entries,
+ * without constantly shifting any around.
+ *
+ * Usage of the previous map would have to reset the head every single usage,
+ * shifting the entire map. Here, nothing happens except an increment when
+ * the cache is hit, and when it needs to replace an old element only a single
+ * element is modified.
+ */
+public class FluidDirectionCache<T> {
+
+ private static class FluidDirectionEntry<T> {
+ private final T data;
+ private final boolean flag;
+ private short uses = 0;
+ private short age = 0;
+
+ private FluidDirectionEntry(T data, boolean flag) {
+ this.data = data;
+ this.flag = flag;
+ }
+
+ public int getValue() {
+ return this.uses - (this.age >> 1); // age isn't as important as uses
+ }
+
+ public void incrementUses() {
+ if (this.uses < Short.MAX_VALUE) {
+ this.uses++;
+ }
+ }
+
+ public void incrementAge() {
+ if (this.age < Short.MAX_VALUE) {
+ this.age++;
+ }
+ }
+ }
+
+ private final FluidDirectionEntry[] entries;
+ private final int mask;
+ private final int maxDistance; // the most amount of entries to check for a value
+
+ public FluidDirectionCache(int size) {
+ float fill = 0.75f;
+
+ int arraySize = HashCommon.arraySize(size, fill);
+ this.entries = new FluidDirectionEntry[arraySize];
+ this.mask = arraySize - 1;
+ this.maxDistance = Math.max(4, arraySize >> 4);
+ }
+
+ public Boolean getValue(T data) {
+ FluidDirectionEntry curr;
+ int pos;
+
+ if ((curr = this.entries[pos = HashCommon.mix(data.hashCode()) & this.mask]) == null) {
+ return null;
+ } else if (data.equals(curr.data)) {
+ curr.incrementUses();
+ return curr.flag;
+ }
+
+ int checked = 1; // start at 1 because we already checked the first spot above
+
+ while ((curr = this.entries[pos = (pos + 1) & this.mask]) != null) {
+ if (data.equals(curr.data)) {
+ curr.incrementUses();
+ return curr.flag;
+ } else if (++checked >= this.maxDistance) {
+ break;
+ }
+ }
+
+ return null;
+ }
+
+ public void putValue(T data, boolean flag) {
+ FluidDirectionEntry<T> curr;
+ int pos;
+
+ if ((curr = this.entries[pos = HashCommon.mix(data.hashCode()) & this.mask]) == null) {
+ this.entries[pos] = new FluidDirectionEntry<>(data, flag); // add
+ return;
+ } else if (data.equals(curr.data)) {
+ curr.incrementUses();
+ return;
+ }
+
+ int checked = 1; // start at 1 because we already checked the first spot above
+
+ while ((curr = this.entries[pos = (pos + 1) & this.mask]) != null) {
+ if (data.equals(curr.data)) {
+ curr.incrementUses();
+ return;
+ } else if (++checked >= this.maxDistance) {
+ this.forceAdd(data, flag);
+ return;
+ }
+ }
+
+ this.entries[pos] = new FluidDirectionEntry<>(data, flag); // add
+ }
+
+ private void forceAdd(T data, boolean flag) {
+ int expectedPos = HashCommon.mix(data.hashCode()) & this.mask;
+
+ int toRemovePos = expectedPos;
+ FluidDirectionEntry<T> entryToRemove = this.entries[toRemovePos];
+
+ for (int i = expectedPos + 1; i < expectedPos + this.maxDistance; i++) {
+ int pos = i & this.mask;
+ FluidDirectionEntry<T> entry = this.entries[pos];
+ if (entry.getValue() < entryToRemove.getValue()) {
+ toRemovePos = pos;
+ entryToRemove = entry;
+ }
+
+ entry.incrementAge(); // use this as a mechanism to age the other entries
+ }
+
+ // remove the least used/oldest entry
+ this.entries[toRemovePos] = new FluidDirectionEntry(data, flag);
+ }
+}
diff --git a/src/main/java/net/minecraft/world/level/block/Block.java b/src/main/java/net/minecraft/world/level/block/Block.java
index 596b4597313b87296d39027b13555b5ad1cba9e6..f8a982add50862f1bc977f3039e7e9aeed9138ae 100644
--- a/src/main/java/net/minecraft/world/level/block/Block.java
+++ b/src/main/java/net/minecraft/world/level/block/Block.java
@@ -392,6 +392,7 @@ public class Block extends BlockBase implements IMaterial {
return this.d;
}
+ /** currently seems to only return true for MOVING_PISTON and SCAFFOLDING */ public boolean isComplexHitbox() { return this.o(); } // Airplane - OBFHELPER
public boolean o() {
return this.aA;
}
diff --git a/src/main/java/net/minecraft/world/level/material/FluidTypeFlowing.java b/src/main/java/net/minecraft/world/level/material/FluidTypeFlowing.java
index 6bb4ec00e40795ced73648fefcd1f5027e0113cd..b14b0134b42aa6d1eb285aa453ec6067cc702878 100644
--- a/src/main/java/net/minecraft/world/level/material/FluidTypeFlowing.java
+++ b/src/main/java/net/minecraft/world/level/material/FluidTypeFlowing.java
@@ -45,6 +45,8 @@ public abstract class FluidTypeFlowing extends FluidType {
public static final BlockStateBoolean FALLING = BlockProperties.i;
public static final BlockStateInteger LEVEL = BlockProperties.at;
+ // Airplane start - use our own threadlocal cache
+ /*
private static final ThreadLocal<Object2ByteLinkedOpenHashMap<Block.a>> e = ThreadLocal.withInitial(() -> {
Object2ByteLinkedOpenHashMap<Block.a> object2bytelinkedopenhashmap = new Object2ByteLinkedOpenHashMap<Block.a>(200) {
protected void rehash(int i) {}
@@ -53,6 +55,13 @@ public abstract class FluidTypeFlowing extends FluidType {
object2bytelinkedopenhashmap.defaultReturnValue((byte) 127);
return object2bytelinkedopenhashmap;
});
+ */
+ private static final ThreadLocal<gg.airplane.structs.FluidDirectionCache<Block.a>> localFluidDirectionCache = ThreadLocal.withInitial(() -> {
+ // Airplane todo - mess with this number for performance
+ // with 1024 it seems very infrequent on a small world that it has to remove old entries
+ return new gg.airplane.structs.FluidDirectionCache<>(1024);
+ });
+ // Airplane end
private final Map<Fluid, VoxelShape> f = Maps.newIdentityHashMap();
public FluidTypeFlowing() {}
@@ -240,6 +249,8 @@ public abstract class FluidTypeFlowing extends FluidType {
}
private boolean a(EnumDirection enumdirection, IBlockAccess iblockaccess, BlockPosition blockposition, IBlockData iblockdata, BlockPosition blockposition1, IBlockData iblockdata1) {
+ // Airplane start - modify to use our cache
+ /*
Object2ByteLinkedOpenHashMap object2bytelinkedopenhashmap;
if (!iblockdata.getBlock().o() && !iblockdata1.getBlock().o()) {
@@ -247,9 +258,16 @@ public abstract class FluidTypeFlowing extends FluidType {
} else {
object2bytelinkedopenhashmap = null;
}
+ */
+ gg.airplane.structs.FluidDirectionCache<Block.a> cache = null;
+
+ if (!iblockdata.getBlock().isComplexHitbox() && !iblockdata1.getBlock().isComplexHitbox()) {
+ cache = localFluidDirectionCache.get();
+ }
Block.a block_a;
+ /*
if (object2bytelinkedopenhashmap != null) {
block_a = new Block.a(iblockdata, iblockdata1, enumdirection);
byte b0 = object2bytelinkedopenhashmap.getAndMoveToFirst(block_a);
@@ -260,11 +278,22 @@ public abstract class FluidTypeFlowing extends FluidType {
} else {
block_a = null;
}
+ */
+ if (cache != null) {
+ block_a = new Block.a(iblockdata, iblockdata1, enumdirection);
+ Boolean flag = cache.getValue(block_a);
+ if (flag != null) {
+ return flag;
+ }
+ } else {
+ block_a = null;
+ }
VoxelShape voxelshape = iblockdata.getCollisionShape(iblockaccess, blockposition);
VoxelShape voxelshape1 = iblockdata1.getCollisionShape(iblockaccess, blockposition1);
boolean flag = !VoxelShapes.b(voxelshape, voxelshape1, enumdirection);
+ /*
if (object2bytelinkedopenhashmap != null) {
if (object2bytelinkedopenhashmap.size() == 200) {
object2bytelinkedopenhashmap.removeLastByte();
@@ -272,6 +301,11 @@ public abstract class FluidTypeFlowing extends FluidType {
object2bytelinkedopenhashmap.putAndMoveToFirst(block_a, (byte) (flag ? 1 : 0));
}
+ */
+ if (cache != null) {
+ cache.putValue(block_a, flag);
+ }
+ // Airplane end
return flag;
}