Paper/Spigot-Server-Patches/0443-Optimise-ArraySetSorted-removeIf.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Wed, 15 Apr 2020 18:23:28 -0700
Subject: [PATCH] Optimise ArraySetSorted#removeIf
Remove iterator allocation and ensure the call is always O(n)
diff --git a/src/main/java/net/minecraft/server/ArraySetSorted.java b/src/main/java/net/minecraft/server/ArraySetSorted.java
index 85f799a713db0c822d46b689010f9f6bd43f5280..7db6b5850b91588eb4d91f0d7e8b5dbbcb95b7cb 100644
--- a/src/main/java/net/minecraft/server/ArraySetSorted.java
+++ b/src/main/java/net/minecraft/server/ArraySetSorted.java
@@ -10,8 +10,8 @@ import java.util.NoSuchElementException;
public class ArraySetSorted<T> extends AbstractSet<T> {
private final Comparator<T> a;
- private T[] b;
- private int c;
+ private T[] b; private final T[] getBackingArray() { return this.b; } // Paper - OBFHELPER
+ private int c; private final int getSize() { return this.c; } private final void setSize(int value) { this.c = value; } // Paper - OBFHELPER
private ArraySetSorted(int i, Comparator<T> comparator) {
this.a = comparator;
@@ -22,6 +22,42 @@ public class ArraySetSorted<T> extends AbstractSet<T> {
}
}
+ // Paper start - optimise removeIf
+ @Override
+ public boolean removeIf(java.util.function.Predicate<? super T> filter) {
+ // prev. impl used an iterator, which could be n^2 and creates garbage
+ int i = 0, len = this.getSize();
+ T[] backingArray = this.getBackingArray();
+
+ for (;;) {
+ if (i >= len) {
+ return false;
+ }
+ if (!filter.test(backingArray[i])) {
+ ++i;
+ continue;
+ }
+ break;
+ }
+
+ // we only want to write back to backingArray if we really need to
+
+ int lastIndex = i; // this is where new elements are shifted to
+
+ for (; i < len; ++i) {
+ T curr = backingArray[i];
+ if (!filter.test(curr)) { // if test throws we're screwed
+ backingArray[lastIndex++] = curr;
+ }
+ }
+
+ // cleanup end
+ Arrays.fill(backingArray, lastIndex, len, null);
+ this.setSize(lastIndex);
+ return true;
+ }
+ // Paper end - optimise removeIf
+
public static <T extends Comparable<T>> ArraySetSorted<T> a(int i) {
return new ArraySetSorted<>(i, (Comparator)Comparator.naturalOrder()); // Paper - decompile fix
}