Commit d5c4c550 authored May 05, 2022 by Songchun Fan

[snapshot] optimizing WatchedArrayList snapshot

ArrayList.add(index, value) does an array copy everytime to extend the
underlying array. Here we already knew the size of that array and
ensured the capacity so we should only call ArrayList.add(value)
which does not involve array copying.

We need to examine other Watched* classes and try to spot performance
issues like this.

BUG: 231373522
Test: forrest run
Change-Id: Iab440fc809072e9b1ee1bef7d69a0dc04207bafb

parent 455e490d

services/core/java/com/android/server/utils/WatchedArrayList.java

+1 −1

Original line number	Diff line number	Diff line
		@@ -416,7 +416,7 @@ public class WatchedArrayList<E> extends WatchableImpl
		dst.mStorage.ensureCapacity(end);
		for (int i = 0; i < end; i++) {
		final E val = Snapshots.maybeSnapshot(src.get(i));
		dst.add(i, val);
		dst.add(val);
		}
		dst.seal();
		}