Use CopyOnWriteArrayList to avoid ConcurrentModificationException

Bug: 149362541
Test: make -j42 RunSettingsLibRoboTests
Change-Id: I9bed14c0141a896ec91d2354df09bb5aaa432dfb

packages/SettingsLib/src/com/android/settingslib/media/LocalMediaManager.java

@@ -35,6 +35,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 /**
  * LocalMediaManager provide interface to get MediaDevice list and transfer media to MediaDevice.
@@ -53,7 +54,7 @@ public class LocalMediaManager implements BluetoothCallback {
         int STATE_DISCONNECTED = 3;
     }
 
-    private final Collection<DeviceCallback> mCallbacks = new ArrayList<>();
+    private final Collection<DeviceCallback> mCallbacks = new CopyOnWriteArrayList<>();
     @VisibleForTesting
     final MediaDeviceCallback mMediaDeviceCallback = new MediaDeviceCallback();
 
@@ -73,18 +74,14 @@ public class LocalMediaManager implements BluetoothCallback {
      * Register to start receiving callbacks for MediaDevice events.
      */
     public void registerCallback(DeviceCallback callback) {
-        synchronized (mCallbacks) {
-            mCallbacks.add(callback);
-        }
+        mCallbacks.add(callback);
     }
 
     /**
      * Unregister to stop receiving callbacks for MediaDevice events
      */
     public void unregisterCallback(DeviceCallback callback) {
-        synchronized (mCallbacks) {
-            mCallbacks.remove(callback);
-        }
+        mCallbacks.remove(callback);
     }
 
     public LocalMediaManager(Context context, String packageName, Notification notification) {
@@ -152,10 +149,8 @@ public class LocalMediaManager implements BluetoothCallback {
     }
 
     void dispatchSelectedDeviceStateChanged(MediaDevice device, @MediaDeviceState int state) {
-        synchronized (mCallbacks) {
-            for (DeviceCallback callback : mCallbacks) {
-                callback.onSelectedDeviceStateChanged(device, state);
-            }
+        for (DeviceCallback callback : getCallbacks()) {
+            callback.onSelectedDeviceStateChanged(device, state);
         }
     }
 
@@ -169,19 +164,15 @@ public class LocalMediaManager implements BluetoothCallback {
     }
 
     void dispatchDeviceListUpdate() {
-        synchronized (mCallbacks) {
-            Collections.sort(mMediaDevices, COMPARATOR);
-            for (DeviceCallback callback : mCallbacks) {
-                callback.onDeviceListUpdate(new ArrayList<>(mMediaDevices));
-            }
+        Collections.sort(mMediaDevices, COMPARATOR);
+        for (DeviceCallback callback : getCallbacks()) {
+            callback.onDeviceListUpdate(new ArrayList<>(mMediaDevices));
         }
     }
 
     void dispatchDeviceAttributesChanged() {
-        synchronized (mCallbacks) {
-            for (DeviceCallback callback : mCallbacks) {
-                callback.onDeviceAttributesChanged();
-            }
+        for (DeviceCallback callback : getCallbacks()) {
+            callback.onDeviceAttributesChanged();
         }
     }
 
@@ -270,6 +261,10 @@ public class LocalMediaManager implements BluetoothCallback {
                 || device.isActiveDevice(BluetoothProfile.HEARING_AID);
     }
 
+    private Collection<DeviceCallback> getCallbacks() {
+        return new CopyOnWriteArrayList<>(mCallbacks);
+    }
+
     class MediaDeviceCallback implements MediaManager.MediaDeviceCallback {
         @Override
         public void onDeviceAdded(MediaDevice device) {

packages/SettingsLib/src/com/android/settingslib/media/MediaManager.java

@@ -22,6 +22,7 @@ import android.util.Log;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 /**
  * MediaManager provide interface to get MediaDevice list.
@@ -30,7 +31,7 @@ public abstract class MediaManager {
 
     private static final String TAG = "MediaManager";
 
-    protected final Collection<MediaDeviceCallback> mCallbacks = new ArrayList<>();
+    protected final Collection<MediaDeviceCallback> mCallbacks = new CopyOnWriteArrayList<>();
     protected final List<MediaDevice> mMediaDevices = new ArrayList<>();
 
     protected Context mContext;
@@ -42,18 +43,14 @@ public abstract class MediaManager {
     }
 
     protected void registerCallback(MediaDeviceCallback callback) {
-        synchronized (mCallbacks) {
-            if (!mCallbacks.contains(callback)) {
-                mCallbacks.add(callback);
-            }
+        if (!mCallbacks.contains(callback)) {
+            mCallbacks.add(callback);
         }
     }
 
     protected void unregisterCallback(MediaDeviceCallback callback) {
-        synchronized (mCallbacks) {
-            if (mCallbacks.contains(callback)) {
-                mCallbacks.remove(callback);
-            }
+        if (mCallbacks.contains(callback)) {
+            mCallbacks.remove(callback);
         }
     }
 
@@ -78,53 +75,45 @@ public abstract class MediaManager {
     }
 
     protected void dispatchDeviceAdded(MediaDevice mediaDevice) {
-        synchronized (mCallbacks) {
-            for (MediaDeviceCallback callback : mCallbacks) {
-                callback.onDeviceAdded(mediaDevice);
-            }
+        for (MediaDeviceCallback callback : getCallbacks()) {
+            callback.onDeviceAdded(mediaDevice);
         }
     }
 
     protected void dispatchDeviceRemoved(MediaDevice mediaDevice) {
-        synchronized (mCallbacks) {
-            for (MediaDeviceCallback callback : mCallbacks) {
-                callback.onDeviceRemoved(mediaDevice);
-            }
+        for (MediaDeviceCallback callback : getCallbacks()) {
+            callback.onDeviceRemoved(mediaDevice);
         }
     }
 
     protected void dispatchDeviceListAdded() {
-        synchronized (mCallbacks) {
-            for (MediaDeviceCallback callback : mCallbacks) {
-                callback.onDeviceListAdded(new ArrayList<>(mMediaDevices));
-            }
+        for (MediaDeviceCallback callback : getCallbacks()) {
+            callback.onDeviceListAdded(new ArrayList<>(mMediaDevices));
         }
     }
 
     protected void dispatchDeviceListRemoved(List<MediaDevice> devices) {
-        synchronized (mCallbacks) {
-            for (MediaDeviceCallback callback : mCallbacks) {
-                callback.onDeviceListRemoved(devices);
-            }
+        for (MediaDeviceCallback callback : getCallbacks()) {
+            callback.onDeviceListRemoved(devices);
         }
     }
 
     protected void dispatchConnectedDeviceChanged(String id) {
-        synchronized (mCallbacks) {
-            for (MediaDeviceCallback callback : mCallbacks) {
-                callback.onConnectedDeviceChanged(id);
-            }
+        for (MediaDeviceCallback callback : getCallbacks()) {
+            callback.onConnectedDeviceChanged(id);
         }
     }
 
     protected void dispatchDataChanged() {
-        synchronized (mCallbacks) {
-            for (MediaDeviceCallback callback : mCallbacks) {
-                callback.onDeviceAttributesChanged();
-            }
+        for (MediaDeviceCallback callback : getCallbacks()) {
+            callback.onDeviceAttributesChanged();
         }
     }
 
+    private Collection<MediaDeviceCallback> getCallbacks() {
+        return new CopyOnWriteArrayList<>(mCallbacks);
+    }
+
     /**
      * Callback for notifying device is added, removed and attributes changed.
      */