Improve forEach.

The default implementation of Collection.forEach() uses the
iterator(). Switch to straight iterating through the array since the
iterator is an inefficient way to access the array contents.

Benchmark results:

Before:

android.util.ArraySetPerfTest#testForEach_Large:
	forEach_Large_median (ns): 398480
	forEach_Large_min (ns): 395758
	forEach_Large_mean (ns): 400957
	forEach_Large_standardDeviation: 5457
android.util.ArraySetPerfTest#testForEach_Small:
	forEach_Small_min (ns): 82768
	forEach_Small_median (ns): 83884
	forEach_Small_standardDeviation: 896
	forEach_Small_mean (ns): 83724

After:

android.util.ArraySetPerfTest#testForEach_Large:
	forEach_Large_median (ns): 319481
	forEach_Large_min (ns): 316166
	forEach_Large_mean (ns): 339865
	forEach_Large_standardDeviation: 44201
android.util.ArraySetPerfTest#testForEach_Small:
	forEach_Small_min (ns): 58736
	forEach_Small_median (ns): 60648
	forEach_Small_standardDeviation: 1375
	forEach_Small_mean (ns): 60622

Bug: 194098491
Test: atest CorePerfTests:ArraySetPerfTest (see results above)
Test: atest CtsUtilTestCases:ArraySetTest
Test: atest FrameworksCoreTests:ArraySetTest
Change-Id: Ib14b96f095203e1f5811132f2a21be0452645f7e

1 files changed, 18 insertions, 0 deletions

diff --git a/core/java/android/util/ArraySet.java b/core/java/android/util/ArraySet.java
index f53548a41177..b5c75b9276b7 100644
--- a/core/java/android/util/ArraySet.java
+++ b/core/java/android/util/ArraySet.java
@@ -28,6 +28,7 @@ import java.util.ConcurrentModificationException;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
+import java.util.function.Consumer;
 import java.util.function.Predicate;
 
 /**
@@ -747,6 +748,23 @@ public final class ArraySet<E> implements Collection<E>, Set<E> {
         return mSize;
     }
 
+    /**
+     * Performs the given action for all elements in the stored order. This implementation overrides
+     * the default implementation to avoid using the {@link #iterator()}.
+     *
+     * @param action The action to be performed for each element
+     */
+    @Override
+    public void forEach(Consumer<? super E> action) {
+        if (action == null) {
+            throw new NullPointerException("action must not be null");
+        }
+
+        for (int i = 0; i < mSize; ++i) {
+            action.accept(valueAt(i));
+        }
+    }
+
     @Override
     public Object[] toArray() {
         Object[] result = new Object[mSize];