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Commit 97d10ffc authored by Hugo Benichi's avatar Hugo Benichi
Browse files

DO NOT MERGE IpConnectivityMetrics: rate limit ApfProgramEvents 

This patch uses the previously introduced TokenBucket to rate limit
ApfProgramEvents, still allowing for burst of ApfProgramEvents when a
new interface is set up (due to ipv4 provisioning, multicast lock, ipv6 RAs
triggering new APF program events in short amounts of time).

Test: new test in IpConnectivityMetricsTest
Bug: 1550402

(cherry picked from commit e1c173d2)

Change-Id: Ibe41e9a76db36ea502697a5f19fc0d91c40a3087
parent ff0b5862

core/java/android/net/IIpConnectivityMetrics.aidl

+2 −1
Original line number Diff line number Diff line
@@ -23,7 +23,8 @@ import android.net.ConnectivityMetricsEvent; 
interface IIpConnectivityMetrics {



    /**

     * @return number of remaining available slots in buffer.

     * @return the number of remaining available slots in buffer,

     * or -1 if the event was dropped due to rate limiting.

     */

    int logEvent(in ConnectivityMetricsEvent event);

}

core/tests/coretests/src/android/util/TokenBucketTest.java

+0 −1
Original line number Diff line number Diff line
@@ -177,4 +177,3 @@ public class TokenBucketTest extends TestCase { 


    interface Fn { void call(); }

}

services/core/java/com/android/server/connectivity/IpConnectivityMetrics.java

+24 −0
Original line number Diff line number Diff line
@@ -19,15 +19,19 @@ package com.android.server.connectivity; 
import android.content.Context;

import android.net.ConnectivityMetricsEvent;

import android.net.IIpConnectivityMetrics;

import android.net.metrics.ApfProgramEvent;

import android.net.metrics.IpConnectivityLog;

import android.os.IBinder;

import android.os.Parcelable;

import android.provider.Settings;

import android.text.TextUtils;

import android.text.format.DateUtils;

import android.util.ArrayMap;

import android.util.Base64;

import android.util.Log;

import com.android.internal.annotations.GuardedBy;

import com.android.internal.annotations.VisibleForTesting;

import com.android.internal.util.TokenBucket;

import com.android.server.SystemService;

import java.io.FileDescriptor;

import java.io.IOException;
@@ -49,6 +53,8 @@ final public class IpConnectivityMetrics extends SystemService { 
    // Maximum size of the event buffer.

    private static final int MAXIMUM_BUFFER_SIZE = DEFAULT_BUFFER_SIZE * 10;



    private static final int ERROR_RATE_LIMITED = -1;



    // Lock ensuring that concurrent manipulations of the event buffer are correct.

    // There are three concurrent operations to synchronize:

    //  - appending events to the buffer.
@@ -66,6 +72,8 @@ final public class IpConnectivityMetrics extends SystemService { 
    private int mDropped;

    @GuardedBy("mLock")

    private int mCapacity;

    @GuardedBy("mLock")

    private final ArrayMap<Class<?>, TokenBucket> mBuckets = makeRateLimitingBuckets();



    private final ToIntFunction<Context> mCapacityGetter;
@@ -115,6 +123,10 @@ final public class IpConnectivityMetrics extends SystemService { 
            if (event == null) {

                return left;

            }

            if (isRateLimited(event)) {

                // Do not count as a dropped event. TODO: consider adding separate counter

                return ERROR_RATE_LIMITED;

            }

            if (left == 0) {

                mDropped++;

                return 0;
@@ -124,6 +136,11 @@ final public class IpConnectivityMetrics extends SystemService { 
        }

    }



    private boolean isRateLimited(ConnectivityMetricsEvent event) {

        TokenBucket tb = mBuckets.get(event.data.getClass());

        return (tb != null) && !tb.get();

    }



    private String flushEncodedOutput() {

        final ArrayList<ConnectivityMetricsEvent> events;

        final int dropped;
@@ -246,4 +263,11 @@ final public class IpConnectivityMetrics extends SystemService { 
        }

        return Math.min(size, MAXIMUM_BUFFER_SIZE);

    };



    private static ArrayMap<Class<?>, TokenBucket> makeRateLimitingBuckets() {

        ArrayMap<Class<?>, TokenBucket> map = new ArrayMap<>();

        // one token every minute, 50 tokens max: burst of ~50 events every hour.

        map.put(ApfProgramEvent.class, new TokenBucket((int)DateUtils.MINUTE_IN_MILLIS, 50));

        return map;

    }

}

services/tests/servicestests/src/com/android/server/connectivity/IpConnectivityMetricsTest.java

+22 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ package com.android.server.connectivity; 
import android.content.Context;

import android.net.ConnectivityMetricsEvent;

import android.net.IIpConnectivityMetrics;

import android.net.metrics.ApfProgramEvent;

import android.net.metrics.ApfStats;

import android.net.metrics.DefaultNetworkEvent;

import android.net.metrics.DhcpClientEvent;
@@ -112,6 +113,27 @@ public class IpConnectivityMetricsTest extends TestCase { 
        assertEquals("", output3);

    }



    public void testRateLimiting() {

        final IpConnectivityLog logger = new IpConnectivityLog(mService.impl);

        final ApfProgramEvent ev = new ApfProgramEvent(0, 0, 0, 0, 0);

        final long fakeTimestamp = 1;



        int attempt = 100; // More than burst quota, but less than buffer size.

        for (int i = 0; i < attempt; i++) {

            logger.log(ev);

        }



        String output1 = getdump("flush");

        assertFalse("".equals(output1));



        for (int i = 0; i < attempt; i++) {

            assertFalse("expected event to be dropped", logger.log(fakeTimestamp, ev));

        }



        String output2 = getdump("flush");

        assertEquals("", output2);

    }



    public void testEndToEndLogging() {

        IpConnectivityLog logger = new IpConnectivityLog(mService.impl);