Merge "Change BinderLatencyBuckets to use int[] instead of ArrayList to improve performance." (0dadb666) · Commits · e / os / android_frameworks_base

core/java/com/android/internal/os/BinderLatencyBuckets.java

+14 −16

Original line number	Diff line number	Diff line
		@@ -20,8 +20,7 @@ import android.util.Slog;

		import com.android.internal.annotations.VisibleForTesting;

		import java.util.ArrayList;
		import java.util.Collections;
		import java.util.Arrays;

		/**
		* Generates the bucket thresholds (with a custom logarithmic scale) for a histogram to store
		@@ -29,7 +28,7 @@ import java.util.Collections;
		*/
		public class BinderLatencyBuckets {
		private static final String TAG = "BinderLatencyBuckets";
		private ArrayList<Integer> mBuckets;
		private final int[] mBuckets;

		/**
		* @param bucketCount the number of buckets the histogram should have
		@@ -37,12 +36,11 @@ public class BinderLatencyBuckets {
		* @param scaleFactor the rate in which each consecutive bucket increases (before rounding)
		*/
		public BinderLatencyBuckets(int bucketCount, int firstBucketSize, float scaleFactor) {
		mBuckets = new ArrayList<>(bucketCount - 1);
		mBuckets.add(firstBucketSize);
		int[] buffer = new int[bucketCount - 1];
		buffer[0] = firstBucketSize;

		// Last value and the target are disjoint as we never want to create buckets smaller than 1.
		double lastTarget = firstBucketSize;
		int lastValue = firstBucketSize;

		// First bucket is already created and the last bucket is anything greater than the final
		// bucket in the list, so create 'bucketCount' - 2 buckets.
		@@ -50,29 +48,29 @@ public class BinderLatencyBuckets {
		// Increase the target bucket limit value by the scale factor.
		double nextTarget = lastTarget * scaleFactor;

		if (nextTarget > Integer.MAX_VALUE \|\| lastValue == Integer.MAX_VALUE) {
		if (nextTarget > Integer.MAX_VALUE) {
		// Do not throw an exception here as this should not affect binder calls.
		Slog.w(TAG, "Attempted to create a bucket larger than maxint");
		mBuckets = Arrays.copyOfRange(buffer, 0, i);
		return;
		}

		if ((int) nextTarget > lastValue) {
		if ((int) nextTarget > buffer[i - 1]) {
		// Convert the target bucket limit value to an integer.
		mBuckets.add((int) nextTarget);
		lastValue = (int) nextTarget;
		buffer[i] = (int) nextTarget;
		} else {
		// Avoid creating redundant buckets, so bucket size should be 1 at a minimum.
		mBuckets.add(lastValue + 1);
		lastValue = lastValue + 1;
		buffer[i] = buffer[i - 1] + 1;
		}
		lastTarget = nextTarget;
		}
		mBuckets = buffer;
		}

		/** Gets the bucket index to insert the provided sample in. */
		public int sampleToBucket(int sample) {
		if (sample > mBuckets.get(mBuckets.size() - 1)) {
		return mBuckets.size();
		if (sample >= mBuckets[mBuckets.length - 1]) {
		return mBuckets.length;
		}

		// Binary search returns the element index if it is contained in the list - in this case the
		@@ -80,12 +78,12 @@ public class BinderLatencyBuckets {
		// Otherwise, it returns (-(insertion point) - 1), where insertion point is the point where
		// to insert the element so that the array remains sorted - in this case the bucket index
		// is the insertion point.
		int searchResult = Collections.binarySearch(mBuckets, sample);
		int searchResult = Arrays.binarySearch(mBuckets, sample);
		return searchResult < 0 ? -(1 + searchResult) : searchResult + 1;
		}

		@VisibleForTesting
		public ArrayList<Integer> getBuckets() {
		public int[] getBuckets() {
		return mBuckets;
		}
		}

core/tests/coretests/src/com/android/internal/os/BinderLatencyBucketsTest.java

+2 −0

Original line number	Diff line number	Diff line
		@@ -36,6 +36,7 @@ public class BinderLatencyBucketsTest {
		public void testBucketThresholds() {
		BinderLatencyBuckets latencyBuckets = new BinderLatencyBuckets(10, 2, 1.45f);
		assertThat(latencyBuckets.getBuckets())
		.asList()
		.containsExactly(2, 3, 4, 6, 8, 12, 18, 26, 39)
		.inOrder();
		}
		@@ -58,6 +59,7 @@ public class BinderLatencyBucketsTest {
		public void testMaxIntBuckets() {
		BinderLatencyBuckets latencyBuckets = new BinderLatencyBuckets(5, Integer.MAX_VALUE / 2, 2);
		assertThat(latencyBuckets.getBuckets())
		.asList()
		.containsExactly(Integer.MAX_VALUE / 2, Integer.MAX_VALUE - 1)
		.inOrder();