Data usage structure optimizations.

Driven by traceview hotspots found in Settings UI.

Change-Id: I614a049523c526b7fcd12fffdf53a3e4723623e4

2 files changed, 89 insertions, 4 deletions

diff --git a/core/java/android/net/NetworkStatsHistory.java b/core/java/android/net/NetworkStatsHistory.java
index d07d899..d8ac31f 100644
--- a/core/java/android/net/NetworkStatsHistory.java
+++ b/core/java/android/net/NetworkStatsHistory.java
@@ -29,6 +29,7 @@ import static android.net.NetworkStatsHistory.ParcelUtils.writeLongArray;
 
 import android.os.Parcel;
 import android.os.Parcelable;
+import android.util.MathUtils;
 
 import java.io.CharArrayWriter;
 import java.io.DataInputStream;
@@ -207,6 +208,34 @@ public class NetworkStatsHistory implements Parcelable {
     }
 
     /**
+     * Return index of bucket that contains or is immediately before the
+     * requested time.
+     */
+    public int getIndexBefore(long time) {
+        int index = Arrays.binarySearch(bucketStart, 0, bucketCount, time);
+        if (index < 0) {
+            index = (~index) - 1;
+        } else {
+            index -= 1;
+        }
+        return MathUtils.constrain(index, 0, bucketCount - 1);
+    }
+
+    /**
+     * Return index of bucket that contains or is immediately after the
+     * requested time.
+     */
+    public int getIndexAfter(long time) {
+        int index = Arrays.binarySearch(bucketStart, 0, bucketCount, time);
+        if (index < 0) {
+            index = ~index;
+        } else {
+            index += 1;
+        }
+        return MathUtils.constrain(index, 0, bucketCount - 1);
+    }
+
+    /**
      * Return specific stats entry.
      */
     public Entry getValues(int i, Entry recycle) {
@@ -247,7 +276,8 @@ public class NetworkStatsHistory implements Parcelable {
 
         // distribute data usage into buckets
         long duration = end - start;
-        for (int i = bucketCount - 1; i >= 0; i--) {
+        final int startIndex = getIndexAfter(end);
+        for (int i = startIndex; i >= 0; i--) {
             final long curStart = bucketStart[i];
             final long curEnd = curStart + bucketDuration;
 
@@ -406,7 +436,8 @@ public class NetworkStatsHistory implements Parcelable {
         entry.txPackets = txPackets != null ? 0 : UNKNOWN;
         entry.operations = operations != null ? 0 : UNKNOWN;
 
-        for (int i = bucketCount - 1; i >= 0; i--) {
+        final int startIndex = getIndexAfter(end);
+        for (int i = startIndex; i >= 0; i--) {
             final long curStart = bucketStart[i];
             final long curEnd = curStart + bucketDuration;
 
@@ -417,8 +448,14 @@ public class NetworkStatsHistory implements Parcelable {
 
             // include full value for active buckets, otherwise only fractional
             final boolean activeBucket = curStart < now && curEnd > now;
-            final long overlap = activeBucket ? bucketDuration
-                    : Math.min(curEnd, end) - Math.max(curStart, start);
+            final long overlap;
+            if (activeBucket) {
+                overlap = bucketDuration;
+            } else {
+                final long overlapEnd = curEnd < end ? curEnd : end;
+                final long overlapStart = curStart > start ? curStart : start;
+                overlap = overlapEnd - overlapStart;
+            }
             if (overlap <= 0) continue;
 
             // integer math each time is faster than floating point
diff --git a/core/tests/coretests/src/android/net/NetworkStatsHistoryTest.java b/core/tests/coretests/src/android/net/NetworkStatsHistoryTest.java
index b888d9a..e1db073 100644
--- a/core/tests/coretests/src/android/net/NetworkStatsHistoryTest.java
+++ b/core/tests/coretests/src/android/net/NetworkStatsHistoryTest.java
@@ -407,6 +407,54 @@ public class NetworkStatsHistoryTest extends AndroidTestCase {
         assertEquals(Long.MAX_VALUE - 40, performVarLong(Long.MAX_VALUE - 40));
     }
 
+    public void testIndexBeforeAfter() throws Exception {
+        final long BUCKET_SIZE = HOUR_IN_MILLIS;
+        stats = new NetworkStatsHistory(BUCKET_SIZE);
+
+        final long FIRST_START = TEST_START;
+        final long FIRST_END = FIRST_START + (2 * HOUR_IN_MILLIS);
+        final long SECOND_START = TEST_START + WEEK_IN_MILLIS;
+        final long SECOND_END = SECOND_START + HOUR_IN_MILLIS;
+        final long THIRD_START = TEST_START + (2 * WEEK_IN_MILLIS);
+        final long THIRD_END = THIRD_START + (2 * HOUR_IN_MILLIS);
+
+        stats.recordData(FIRST_START, FIRST_END,
+                new NetworkStats.Entry(1024L, 10L, 2048L, 20L, 2L));
+        stats.recordData(SECOND_START, SECOND_END,
+                new NetworkStats.Entry(1024L, 10L, 2048L, 20L, 2L));
+        stats.recordData(THIRD_START, THIRD_END,
+                new NetworkStats.Entry(1024L, 10L, 2048L, 20L, 2L));
+
+        // should have buckets: 2+1+2
+        assertEquals(5, stats.size());
+
+        assertIndexBeforeAfter(stats, 0, 0, Long.MIN_VALUE);
+        assertIndexBeforeAfter(stats, 0, 1, FIRST_START);
+        assertIndexBeforeAfter(stats, 0, 1, FIRST_START + MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 0, 2, FIRST_START + HOUR_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 1, 2, FIRST_START + HOUR_IN_MILLIS + MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 1, 2, FIRST_END - MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 1, 2, FIRST_END);
+        assertIndexBeforeAfter(stats, 1, 2, FIRST_END + MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 1, 2, SECOND_START - MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 1, 3, SECOND_START);
+        assertIndexBeforeAfter(stats, 2, 3, SECOND_END);
+        assertIndexBeforeAfter(stats, 2, 3, SECOND_END + MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 2, 3, THIRD_START - MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 2, 4, THIRD_START);
+        assertIndexBeforeAfter(stats, 3, 4, THIRD_START + MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 3, 4, THIRD_START + HOUR_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 4, 4, THIRD_END);
+        assertIndexBeforeAfter(stats, 4, 4, THIRD_END + MINUTE_IN_MILLIS);
+        assertIndexBeforeAfter(stats, 4, 4, Long.MAX_VALUE);
+    }
+
+    private static void assertIndexBeforeAfter(
+            NetworkStatsHistory stats, int before, int after, long time) {
+        assertEquals("unexpected before", before, stats.getIndexBefore(time));
+        assertEquals("unexpected after", after, stats.getIndexAfter(time));
+    }
+
     private static long performVarLong(long before) throws Exception {
         final ByteArrayOutputStream out = new ByteArrayOutputStream();
         writeVarLong(new DataOutputStream(out), before);