Paper/patches/unapplied/server/0408-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/util/SortedArraySet.java b/src/main/java/net/minecraft/util/SortedArraySet.java
index d1b2ba24ef54e01c6249c3b2ca16e80f03c001a6..5f1c4c6b9e36f2d6ec43b82cc0e2cae24b800dc4 100644
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--- a/src/main/java/net/minecraft/util/SortedArraySet.java
+++ b/src/main/java/net/minecraft/util/SortedArraySet.java
@@ -22,6 +22,41 @@ public class SortedArraySet<T> extends AbstractSet<T> {
this.contents = (T[])castRawArray(new Object[initialCapacity]);
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}
}
+ // 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.size;
+ T[] backingArray = this.contents;
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+
+ 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.size = lastIndex;
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+ return true;
+ }
+ // Paper end - optimise removeIf
public static <T extends Comparable<T>> SortedArraySet<T> create() {
return create(10);