Merge "Use CopyOnWriteArrayList to store list of NetworkStatsProviderCb" am: 9aa60f31da

Change-Id: I51dfa3882e33db89d40b9e912d5178096c724de6

services/core/java/com/android/server/net/NetworkStatsService.java

@@ -119,7 +119,6 @@ import android.os.Looper;
 import android.os.Message;
 import android.os.Messenger;
 import android.os.PowerManager;
-import android.os.RemoteCallbackList;
 import android.os.RemoteException;
 import android.os.SystemClock;
 import android.os.Trace;
@@ -160,6 +159,7 @@ import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Objects;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
@@ -226,12 +226,6 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     private static final String PREFIX_UID = "uid";
     private static final String PREFIX_UID_TAG = "uid_tag";
 
-    /**
-     * Virtual network interface for video telephony. This is for VT data usage counting purpose.
-     */
-    // TODO: Remove this after no one is using it.
-    public static final String VT_INTERFACE = NetworkStats.IFACE_VT;
-
     /**
      * Settings that can be changed externally.
      */
@@ -304,8 +298,8 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             new DropBoxNonMonotonicObserver();
 
     private static final int MAX_STATS_PROVIDER_POLL_WAIT_TIME_MS = 100;
-    private final RemoteCallbackList<NetworkStatsProviderCallbackImpl> mStatsProviderCbList =
+    private final CopyOnWriteArrayList<NetworkStatsProviderCallbackImpl> mStatsProviderCbList =
-            new RemoteCallbackList<>();
+            new CopyOnWriteArrayList<>();
     /** Semaphore used to wait for stats provider to respond to request stats update. */
     private final Semaphore mStatsProviderSem = new Semaphore(0, true);
 
@@ -1461,10 +1455,14 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         final boolean persistForce = (flags & FLAG_PERSIST_FORCE) != 0;
 
         // Request asynchronous stats update from all providers for next poll. And wait a bit of
-        // time to allow providers report-in given that normally binder call should be fast.
+        // time to allow providers report-in given that normally binder call should be fast. Note
+        // that size of list might be changed because addition/removing at the same time. For
+        // addition, the stats of the missed provider can only be collected in next poll;
+        // for removal, wait might take up to MAX_STATS_PROVIDER_POLL_WAIT_TIME_MS
+        // once that happened.
         // TODO: request with a valid token.
         Trace.traceBegin(TRACE_TAG_NETWORK, "provider.requestStatsUpdate");
-        final int registeredCallbackCount = mStatsProviderCbList.getRegisteredCallbackCount();
+        final int registeredCallbackCount = mStatsProviderCbList.size();
         mStatsProviderSem.drainPermits();
         invokeForAllStatsProviderCallbacks(
                 (cb) -> cb.mProvider.onRequestStatsUpdate(0 /* unused */));
@@ -1638,7 +1636,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
         @Override
         public void setStatsProviderLimitAsync(@NonNull String iface, long quota) {
-            Slog.v(TAG, "setStatsProviderLimitAsync(" + iface + "," + quota + ")");
+            if (LOGV) Slog.v(TAG, "setStatsProviderLimitAsync(" + iface + "," + quota + ")");
             invokeForAllStatsProviderCallbacks((cb) -> cb.mProvider.onSetLimit(iface, quota));
         }
     }
@@ -1929,7 +1927,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
             NetworkStatsProviderCallbackImpl callback = new NetworkStatsProviderCallbackImpl(
                     tag, provider, mStatsProviderSem, mAlertObserver,
                     mStatsProviderCbList);
-            mStatsProviderCbList.register(callback);
+            mStatsProviderCbList.add(callback);
             Log.d(TAG, "registerNetworkStatsProvider from " + callback.mTag + " uid/pid="
                     + getCallingUid() + "/" + getCallingPid());
             return callback;
@@ -1953,22 +1951,13 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
     private void invokeForAllStatsProviderCallbacks(
             @NonNull ThrowingConsumer<NetworkStatsProviderCallbackImpl, RemoteException> task) {
-        synchronized (mStatsLock) {
+        for (final NetworkStatsProviderCallbackImpl cb : mStatsProviderCbList) {
-            final int length = mStatsProviderCbList.beginBroadcast();
-            try {
-                for (int i = 0; i < length; i++) {
-                    final NetworkStatsProviderCallbackImpl cb =
-                            mStatsProviderCbList.getBroadcastItem(i);
             try {
                 task.accept(cb);
             } catch (RemoteException e) {
                 Log.e(TAG, "Fail to broadcast to provider: " + cb.mTag, e);
             }
         }
-            } finally {
-                mStatsProviderCbList.finishBroadcast();
-            }
-        }
     }
 
     private static class NetworkStatsProviderCallbackImpl extends INetworkStatsProviderCallback.Stub
@@ -1978,7 +1967,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         @NonNull final INetworkStatsProvider mProvider;
         @NonNull private final Semaphore mSemaphore;
         @NonNull final INetworkManagementEventObserver mAlertObserver;
-        @NonNull final RemoteCallbackList<NetworkStatsProviderCallbackImpl> mStatsProviderCbList;
+        @NonNull final CopyOnWriteArrayList<NetworkStatsProviderCallbackImpl> mStatsProviderCbList;
 
         @NonNull private final Object mProviderStatsLock = new Object();
 
@@ -1992,7 +1981,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
                 @NonNull String tag, @NonNull INetworkStatsProvider provider,
                 @NonNull Semaphore semaphore,
                 @NonNull INetworkManagementEventObserver alertObserver,
-                @NonNull RemoteCallbackList<NetworkStatsProviderCallbackImpl> cbList)
+                @NonNull CopyOnWriteArrayList<NetworkStatsProviderCallbackImpl> cbList)
                 throws RemoteException {
             mTag = tag;
             mProvider = provider;
@@ -2049,13 +2038,13 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         @Override
         public void binderDied() {
             Log.d(TAG, mTag + ": binderDied");
-            mStatsProviderCbList.unregister(this);
+            mStatsProviderCbList.remove(this);
         }
 
         @Override
         public void unregister() {
             Log.d(TAG, mTag + ": unregister");
-            mStatsProviderCbList.unregister(this);
+            mStatsProviderCbList.remove(this);
         }
 
     }