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Commit 881d91fe authored by Kyunglyul Hyun's avatar Kyunglyul Hyun
Browse files

Prevent CME by using CopyOnWriteArraySet 

A thread enumerating trackers could be
different form a therad adding/removing a tracker.
By using CopyOnWriteArraySet, we can prevent
ConcurrentModificationException.

Bug: 312945444
Flag: EXTEMPT, no logical changes
Test: atest DistanceMeasurementManagerTest --iterations 200
Change-Id: I67c07a13aee08e7a0ac35c9c250c7700dfcb56cd
parent 115e5865

android/app/src/com/android/bluetooth/gatt/DistanceMeasurementManager.java

+16 −23
Original line number Diff line number Diff line
@@ -31,12 +31,12 @@ import android.util.Log; 
import com.android.bluetooth.btservice.AdapterService;

import com.android.internal.annotations.VisibleForTesting;



import java.util.HashSet;

import java.util.UUID;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.CopyOnWriteArraySet;



/**

 * Manages distnace measurement operations and interacts with Gabeldorsche stack.

 * Manages distance measurement operations and interacts with Gabeldorsche stack.

 *

 * @hide

 */
@@ -52,12 +52,10 @@ public class DistanceMeasurementManager { 
    private final AdapterService mAdapterService;

    private HandlerThread mHandlerThread;

    DistanceMeasurementNativeInterface mDistanceMeasurementNativeInterface;

    private ConcurrentHashMap<String, HashSet<DistanceMeasurementTracker>> mRssiTrackers =

            new ConcurrentHashMap<>();

    private final ConcurrentHashMap<String, CopyOnWriteArraySet<DistanceMeasurementTracker>>

            mRssiTrackers = new ConcurrentHashMap<>();



    /**

     * Constructor of {@link DistanceMeasurementManager}.

     */

    /** Constructor of {@link DistanceMeasurementManager}. */

    DistanceMeasurementManager(AdapterService adapterService) {

        mAdapterService = adapterService;
@@ -111,14 +109,13 @@ public class DistanceMeasurementManager { 
    }



    private synchronized void startRssiTracker(DistanceMeasurementTracker tracker) {

        mRssiTrackers.putIfAbsent(tracker.mIdentityAddress,

                new HashSet<DistanceMeasurementTracker>());

        HashSet<DistanceMeasurementTracker> set = mRssiTrackers.get(tracker.mIdentityAddress);

        if (set.contains(tracker)) {

        mRssiTrackers.putIfAbsent(tracker.mIdentityAddress, new CopyOnWriteArraySet<>());

        CopyOnWriteArraySet<DistanceMeasurementTracker> set =

                mRssiTrackers.get(tracker.mIdentityAddress);

        if (!set.add(tracker)) {

            Log.w(TAG, "Already registered");

            return;

        }

        set.add(tracker);

        mDistanceMeasurementNativeInterface.startDistanceMeasurement(tracker.mIdentityAddress,

                tracker.mFrequency, DistanceMeasurementMethod.DISTANCE_MEASUREMENT_METHOD_RSSI);

    }
@@ -151,7 +148,7 @@ public class DistanceMeasurementManager { 


    private synchronized int stopRssiTracker(UUID uuid, String identityAddress,

            boolean timeout) {

        HashSet<DistanceMeasurementTracker> set = mRssiTrackers.get(identityAddress);

        CopyOnWriteArraySet<DistanceMeasurementTracker> set = mRssiTrackers.get(identityAddress);

        if (set == null) {

            Log.w(TAG, "Can't find rssi tracker");

            return BluetoothStatusCodes.ERROR_DISTANCE_MEASUREMENT_INTERNAL;
@@ -231,7 +228,7 @@ public class DistanceMeasurementManager { 
    }



    void handleRssiStarted(String address) {

        HashSet<DistanceMeasurementTracker> set = mRssiTrackers.get(address);

        CopyOnWriteArraySet<DistanceMeasurementTracker> set = mRssiTrackers.get(address);

        if (set == null) {

            Log.w(TAG, "Can't find rssi tracker");

            return;
@@ -262,7 +259,7 @@ public class DistanceMeasurementManager { 
    }



    void handleRssiStartFail(String address, int reason) {

        HashSet<DistanceMeasurementTracker> set = mRssiTrackers.get(address);

        CopyOnWriteArraySet<DistanceMeasurementTracker> set = mRssiTrackers.get(address);

        if (set == null) {

            Log.w(TAG, "Can't find rssi tracker");

            return;
@@ -272,10 +269,8 @@ public class DistanceMeasurementManager { 
                invokeStartFail(tracker.mCallback, tracker.mDevice, reason);

            }

        }

        synchronized (set) {

        set.removeIf(tracker -> !tracker.mStarted);

    }

    }



    void onDistanceMeasurementStopped(String address, int reason, int method) {

        logd("onDistanceMeasurementStopped address:" + BluetoothUtils.toAnonymizedAddress(address)
@@ -290,7 +285,7 @@ public class DistanceMeasurementManager { 
    }



    void handleRssiStopped(String address, int reason) {

        HashSet<DistanceMeasurementTracker> set = mRssiTrackers.get(address);

        CopyOnWriteArraySet<DistanceMeasurementTracker> set = mRssiTrackers.get(address);

        if (set == null) {

            Log.w(TAG, "Can't find rssi tracker");

            return;
@@ -301,10 +296,8 @@ public class DistanceMeasurementManager { 
                invokeOnStopped(tracker.mCallback, tracker.mDevice, reason);

            }

        }

        synchronized (set) {

        set.removeIf(tracker -> tracker.mStarted);

    }

    }



    void onDistanceMeasurementResult(String address, int centimeter, int errorCentimeter,

            int azimuthAngle, int errorAzimuthAngle, int altitudeAngle, int errorAltitudeAngle,
@@ -323,7 +316,7 @@ public class DistanceMeasurementManager { 
    }



    void handleRssiResult(String address, DistanceMeasurementResult result) {

        HashSet<DistanceMeasurementTracker> set = mRssiTrackers.get(address);

        CopyOnWriteArraySet<DistanceMeasurementTracker> set = mRssiTrackers.get(address);

        if (set == null) {

            Log.w(TAG, "Can't find rssi tracker");

            return;