Create network change notifier.

talk/app/webrtc/java/android/org/webrtc/NetworkMonitor.java

Index: talk/app/webrtc/java/android/org/webrtc/NetworkMonitor.java
diff --git a/talk/app/webrtc/java/android/org/webrtc/NetworkMonitor.java b/talk/app/webrtc/java/android/org/webrtc/NetworkMonitor.java
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+/*
+ * libjingle
+ * Copyright 2015 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *  3. The name of the author may not be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.webrtc;
+
+import static org.webrtc.NetworkMonitorAutoDetect.ConnectionType;
+import static org.webrtc.NetworkMonitorAutoDetect.INVALID_NET_ID;
+
+import android.content.Context;
+import android.util.Log;
+
+import java.util.ArrayList;
+
+/**
+ * Borrowed from Chromium's src/net/android/java/src/org/chromium/net/NetworkChangeNotifier.java
+ *
+ * Triggers updates to the underlying network state from OS networking events.
+ *
+ * WARNING: This class is not thread-safe.
+ */
+public class NetworkMonitor {
+  /**
+   * Alerted when the connection type of the network changes.
+   * The alert is fired on the UI thread.
+   */
+  public interface NetworkObserver {
+    public void onConnectionTypeChanged(ConnectionType connectionType);
+  }
+
+  private static final String TAG = "NetworkMonitor";
+  private static NetworkMonitor instance;
+
+  private final Context applicationContext;
+
+  // Native observers of the connection type changes.
+  private final ArrayList<Long> nativeNetworkObservers;
+  // Java observers of the connection type changes.
+  private final ArrayList<NetworkObserver> networkObservers;
+
+  // Object that detects the connection type changes.
+  private NetworkMonitorAutoDetect autoDetector;
+
+  private ConnectionType currentConnectionType = ConnectionType.CONNECTION_UNKNOWN;
+
+  private NetworkMonitor(Context context) {
+    assertIsTrue(context != null);
+    applicationContext =
+        context.getApplicationContext() == null ? context : context.getApplicationContext();
+
+    nativeNetworkObservers = new ArrayList<Long>();
+    networkObservers = new ArrayList<NetworkObserver>();
+  }
+
+  /**
+   * Initializes the singleton once.
+   * Called from the native code.
+   */
+  public static NetworkMonitor init(Context context) {
+    if (!isInitialized()) {
+      instance = new NetworkMonitor(context);
+    }
+    return instance;
+  }
+
+  public static boolean isInitialized() {
+    return instance != null;
+  }
+
+  /**
+   * Returns the singleton instance.
+   */
+  public static NetworkMonitor getInstance() {
+    return instance;
+  }
+
+  /**
+   * Enables auto detection of the current network state based on notifications from the system.
+   * Note that passing true here requires the embedding app have the platform ACCESS_NETWORK_STATE
+   * permission.
+   *
+   * @param shouldAutoDetect true if the NetworkMonitor should listen for system changes in
+   *  network connectivity.
+   */
+  public static void setAutoDetectConnectivityState(boolean shouldAutoDetect) {
+    getInstance().setAutoDetectConnectivityStateInternal(shouldAutoDetect);
+  }
+
+  private static void assertIsTrue(boolean condition) {
+    if (!condition) {
+      throw new AssertionError("Expected to be true");
+    }
+  }
+
+  // Called by the native code.
+  private void startMonitoring(long nativeObserver) {
+    Log.d(TAG, "Start monitoring from native observer " + nativeObserver);
+    nativeNetworkObservers.add(nativeObserver);
+    setAutoDetectConnectivityStateInternal(true);
+  }
+
+  // Called by the native code.
+  private void stopMonitoring(long nativeObserver) {
+    Log.d(TAG, "Stop monitoring from native observer " + nativeObserver);
+    setAutoDetectConnectivityStateInternal(false);
+    nativeNetworkObservers.remove(nativeObserver);
+  }
+
+  private ConnectionType getCurrentConnectionType() {
+    return currentConnectionType;
+  }
+
+  private int getCurrentDefaultNetId() {
+    return autoDetector == null ? INVALID_NET_ID : autoDetector.getDefaultNetId();
+  }
+
+  private void destroyAutoDetector() {
+    if (autoDetector != null) {
+      autoDetector.destroy();
+      autoDetector = null;
+    }
+  }
+
+  private void setAutoDetectConnectivityStateInternal(boolean shouldAutoDetect) {
+    if (!shouldAutoDetect) {
+      destroyAutoDetector();
+      return;
+    }
+    if (autoDetector == null) {
+      autoDetector = new NetworkMonitorAutoDetect(
+        new NetworkMonitorAutoDetect.Observer() {
+          @Override
+          public void onConnectionTypeChanged(ConnectionType newConnectionType) {
+            updateCurrentConnectionType(newConnectionType);
+          }
+        },
+        applicationContext);
+      final NetworkMonitorAutoDetect.NetworkState networkState =
+          autoDetector.getCurrentNetworkState();
+      updateCurrentConnectionType(autoDetector.getCurrentConnectionType(networkState));
+    }
+  }
+
+  private void updateCurrentConnectionType(ConnectionType newConnectionType) {
+    currentConnectionType = newConnectionType;
+    notifyObserversOfConnectionTypeChange(newConnectionType);
+  }
+
+  /**
+   * Alerts all observers of a connection change.
+   */
+  private void notifyObserversOfConnectionTypeChange(ConnectionType newConnectionType) {
+    for (long nativeObserver : nativeNetworkObservers) {
+      nativeNotifyConnectionTypeChanged(nativeObserver);
+    }
+    for (NetworkObserver observer : networkObservers) {
+      observer.onConnectionTypeChanged(newConnectionType);
+    }
+  }
+
+  /**
+   * Adds an observer for any connection type changes.
+   */
+  public static void addNetworkObserver(NetworkObserver observer) {
+    getInstance().addNetworkObserverInternal(observer);
+  }
+
+  private void addNetworkObserverInternal(NetworkObserver observer) {
+    networkObservers.add(observer);
+  }
+
+  /**
+   * Removes an observer for any connection type changes.
+   */
+  public static void removeNetworkObserver(NetworkObserver observer) {
+    getInstance().removeNetworkObserverInternal(observer);
+  }
+
+  private void removeNetworkObserverInternal(NetworkObserver observer) {
+    networkObservers.remove(observer);
+  }
+
+  /**
+   * Checks if there currently is connectivity.
+   */
+  public static boolean isOnline() {
+    ConnectionType connectionType = getInstance().getCurrentConnectionType();
+    return connectionType != ConnectionType.CONNECTION_UNKNOWN
+        && connectionType != ConnectionType.CONNECTION_NONE;
+  }
+
+  private native long nativeCreateNetworkMonitor();
+
+  private native void nativeNotifyConnectionTypeChanged(long nativePtr);
+
+  // For testing only.
+  static void resetInstanceForTests(Context context) {
+    instance = new NetworkMonitor(context);
+  }
+
+  // For testing only.
+  public static NetworkMonitorAutoDetect getAutoDetectorForTest() {
+    return getInstance().autoDetector;
+  }
+}