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Commit 3f391355 authored by Jeff Sharkey's avatar Jeff Sharkey
Browse files

Persist network stats using AtomicFile. 

Implements read/write of network stats using AtomicFile, along with
magic number and versioning.  Stores in "/data/system/netstats.bin"
for now.  Tests to verify that stats are persisted across a simulated
reboot, and to verify that TEMPLATE_WIFI is working.

Fixed bug where kernel counters rolling backwards would cause negative
stats to be recorded; now we clamp deltas at 0.

Change-Id: I53bce26fc8fd3f4ab1e34ce135d302edfa34db34
parent f24ed1c2

core/java/android/net/INetworkStatsService.aidl

+1 −1
Original line number Diff line number Diff line
@@ -28,6 +28,6 @@ interface INetworkStatsService { 
    NetworkStatsHistory getHistoryForUid(int uid, int networkTemplate);



    /** Return usage summary per UID for traffic that matches template. */

    NetworkStats getSummaryPerUid(long start, long end, int networkTemplate);

    NetworkStats getSummaryForAllUid(long start, long end, int networkTemplate);



}

core/java/android/net/NetworkStats.java

+34 −3
Original line number Diff line number Diff line
@@ -153,6 +153,30 @@ public class NetworkStats implements Parcelable { 
        return result;

    }



    /**

     * Subtract the given {@link NetworkStats}, effectively leaving the delta

     * between two snapshots in time. Assumes that statistics rows collect over

     * time, and that none of them have disappeared.

     *

     * @throws IllegalArgumentException when given {@link NetworkStats} is

     *             non-monotonic.

     */

    public NetworkStats subtract(NetworkStats value) {

        return subtract(value, true, false);

    }



    /**

     * Subtract the given {@link NetworkStats}, effectively leaving the delta

     * between two snapshots in time. Assumes that statistics rows collect over

     * time, and that none of them have disappeared.

     * <p>

     * Instead of throwing when counters are non-monotonic, this variant clamps

     * results to never be negative.

     */

    public NetworkStats subtractClamped(NetworkStats value) {

        return subtract(value, false, true);

    }



    /**

     * Subtract the given {@link NetworkStats}, effectively leaving the delta

     * between two snapshots in time. Assumes that statistics rows collect over
@@ -160,8 +184,11 @@ public class NetworkStats implements Parcelable { 
     *

     * @param enforceMonotonic Validate that incoming value is strictly

     *            monotonic compared to this object.

     * @param clampNegative Instead of throwing like {@code enforceMonotonic},

     *            clamp resulting counters at 0 to prevent negative values.

     */

    public NetworkStats subtract(NetworkStats value, boolean enforceMonotonic) {

    private NetworkStats subtract(

            NetworkStats value, boolean enforceMonotonic, boolean clampNegative) {

        final long deltaRealtime = this.elapsedRealtime - value.elapsedRealtime;

        if (enforceMonotonic && deltaRealtime < 0) {

            throw new IllegalArgumentException("found non-monotonic realtime");
@@ -181,11 +208,15 @@ public class NetworkStats implements Parcelable { 
                result.addEntry(iface, uid, this.rx[i], this.tx[i]);

            } else {

                // existing row, subtract remote value

                final long rx = this.rx[i] - value.rx[j];

                final long tx = this.tx[i] - value.tx[j];

                long rx = this.rx[i] - value.rx[j];

                long tx = this.tx[i] - value.tx[j];

                if (enforceMonotonic && (rx < 0 || tx < 0)) {

                    throw new IllegalArgumentException("found non-monotonic values");

                }

                if (clampNegative) {

                    rx = Math.max(0, rx);

                    tx = Math.max(0, tx);

                }

                result.addEntry(iface, uid, rx, tx);

            }

        }

core/java/android/net/NetworkStatsHistory.java

+5 −1
Original line number Diff line number Diff line
@@ -218,7 +218,7 @@ public class NetworkStatsHistory implements Parcelable { 
     * Return interpolated data usage across the requested range. Interpolates

     * across buckets, so values may be rounded slightly.

     */

    public void getTotalData(long start, long end, long[] outTotal) {

    public long[] getTotalData(long start, long end, long[] outTotal) {

        long rx = 0;

        long tx = 0;
@@ -238,8 +238,12 @@ public class NetworkStatsHistory implements Parcelable { 
            }

        }



        if (outTotal == null || outTotal.length != 2) {

            outTotal = new long[2];

        }

        outTotal[0] = rx;

        outTotal[1] = tx;

        return outTotal;

    }



    /**

core/java/android/net/TrafficStats.java

+2 −2
Original line number Diff line number Diff line
@@ -177,8 +177,8 @@ public class TrafficStats { 


            // subtract starting values and return delta

            final NetworkStats profilingStop = getNetworkStatsForUid(context);

            final NetworkStats profilingDelta = profilingStop.subtract(

                    sActiveProfilingStart, false);

            final NetworkStats profilingDelta = profilingStop.subtractClamped(

                    sActiveProfilingStart);

            sActiveProfilingStart = null;

            return profilingDelta;

        }

core/tests/coretests/src/android/net/NetworkStatsTest.java

+3 −3
Original line number Diff line number Diff line
@@ -47,7 +47,7 @@ public class NetworkStatsTest extends TestCase { 
                .addEntry(TEST_IFACE, 100, 1024, 0)

                .addEntry(TEST_IFACE, 101, 0, 1024).build();



        final NetworkStats result = after.subtract(before, true);

        final NetworkStats result = after.subtract(before);



        // identical data should result in zero delta

        assertEquals(0, result.rx[0]);
@@ -65,7 +65,7 @@ public class NetworkStatsTest extends TestCase { 
                .addEntry(TEST_IFACE, 100, 1025, 2)

                .addEntry(TEST_IFACE, 101, 3, 1028).build();



        final NetworkStats result = after.subtract(before, true);

        final NetworkStats result = after.subtract(before);



        // expect delta between measurements

        assertEquals(1, result.rx[0]);
@@ -84,7 +84,7 @@ public class NetworkStatsTest extends TestCase { 
                .addEntry(TEST_IFACE, 101, 0, 1024)

                .addEntry(TEST_IFACE, 102, 1024, 1024).build();



        final NetworkStats result = after.subtract(before, true);

        final NetworkStats result = after.subtract(before);



        // its okay to have new rows

        assertEquals(0, result.rx[0]);