Fix background ANR from connectivity broadcast receiver

Replace the deprecated CONNECTIVITY_ACTION BroadcastReceiver
(ConnectionChangeReceiver) with a ConnectivityManager.NetworkCallback
(NetworkConnectionMonitor) registered on a background thread. Connectivity
checks and the EventBus dispatch no longer run on the main thread, and a
NetworkCallback is not a broadcast so it cannot trip the background-broadcast
ANR timeout. The monitor is registered once for the process lifetime, dropping
the unreliable foreground/background register/unregister workaround.

The ConnectionChangeEvent contract is preserved, so subscribers are unchanged
apart from the renamed enclosing type.

Sentry: JETPACK-ANDROID-PB9

Author: nbradbury

WordPress/src/main/java/org/wordpress/android/AppInitializer.kt

@@ -11,12 +11,9 @@ import android.app.NotificationManager
 import android.app.SyncNotedAppOp
 import android.content.ComponentCallbacks2
 import android.content.Context
-import android.content.ContextWrapper
-import android.content.IntentFilter
 import android.content.res.Configuration
 import android.database.SQLException
 import android.database.sqlite.SQLiteException
-import android.net.ConnectivityManager
 import android.net.http.HttpResponseCache
 import android.os.Build
 import android.os.Build.VERSION_CODES
@@ -67,7 +64,7 @@ import org.wordpress.android.fluxc.store.StatsStore
 import org.wordpress.android.fluxc.tools.FluxCImageLoader
 import org.wordpress.android.fluxc.utils.ErrorUtils.OnUnexpectedError
 import org.wordpress.android.modules.APPLICATION_SCOPE
-import org.wordpress.android.networking.ConnectionChangeReceiver
+import org.wordpress.android.networking.NetworkConnectionMonitor
 import org.wordpress.android.networking.OAuthAuthenticator
 import org.wordpress.android.networking.RestClientUtils
 import org.wordpress.android.push.GCMRegistrationScheduler
@@ -92,7 +89,6 @@ import org.wordpress.android.ui.uploads.UploadService
 import org.wordpress.android.ui.uploads.UploadStarter
 import org.wordpress.android.util.AppLog
 import org.wordpress.android.util.AppLog.T
-import org.wordpress.android.util.AppLog.T.MAIN
 import org.wordpress.android.util.AppThemeUtils
 import org.wordpress.android.util.BitmapLruCache
 import org.wordpress.android.util.BuildConfigWrapper
@@ -148,6 +144,9 @@ class AppInitializer @Inject constructor(
     @Inject
     lateinit var uploadStarter: UploadStarter
 
+    @Inject
+    lateinit var networkConnectionMonitor: NetworkConnectionMonitor
+
     @Inject
     lateinit var statsWidgetUpdaters: StatsWidgetUpdaters
 
@@ -339,6 +338,11 @@ class AppInitializer @Inject constructor(
         // Make the UploadStarter observe the app process so it can auto-start uploads
         uploadStarter.activateAutoUploading(ProcessLifecycleOwner.get() as ProcessLifecycleOwner)
 
+        // Monitor default-network connectivity for the whole process lifetime. Uses a NetworkCallback on a
+        // background thread instead of the deprecated CONNECTIVITY_ACTION broadcast, so it can't cause a
+        // background ANR. start() is idempotent, so it's safe if init() runs more than once.
+        networkConnectionMonitor.start(application)
+
         initAnalytics(SystemClock.elapsedRealtime() - startDate)
 
         updateNotificationSettings()
@@ -792,7 +796,6 @@ class AppInitializer @Inject constructor(
     inner class ApplicationLifecycleMonitor {
         private var lastPingDate: Date? = null
         private var applicationOpenedDate: Date? = null
-        private var connectionReceiverRegistered = false
         var firstActivityResumed = true
 
         private val isPushNotificationPingNeeded: Boolean
@@ -845,18 +848,6 @@ class AppInitializer @Inject constructor(
 
             AnalyticsTracker.track(Stat.APPLICATION_CLOSED, properties)
             AnalyticsTracker.endSession(false)
-            // Methods onAppComesFromBackground and onAppGoesToBackground are only workarounds to track when the app
-            // goes to or comes from background. The workarounds are not 100% reliable, so avoid unregistering the
-            // receiver twice.
-            if (connectionReceiverRegistered) {
-                connectionReceiverRegistered = false
-                try {
-                    application.unregisterReceiver(ConnectionChangeReceiver.getInstance())
-                    AppLog.d(MAIN, "ConnectionChangeReceiver successfully unregistered")
-                } catch (e: IllegalArgumentException) {
-                    AppLog.e(MAIN, "ConnectionChangeReceiver was already unregistered")
-                }
-            }
 
             // Disable the widgets if needed
             disableWidgetReceiversIfNeeded()
@@ -876,25 +867,6 @@ class AppInitializer @Inject constructor(
             }
             WordPress.appIsInTheBackground = false
 
-            // https://developer.android.com/reference/android/net/ConnectivityManager.html
-            // Apps targeting Android 7.0 (API level 24) and higher do not receive this broadcast if the broadcast
-            // receiver is declared in their manifest. Apps will still receive broadcasts if BroadcastReceiver is
-            // registered with Context.registerReceiver() and that context is still valid.
-            if (!connectionReceiverRegistered) {
-                connectionReceiverRegistered = true
-                if (Build.VERSION.SDK_INT >= VERSION_CODES.UPSIDE_DOWN_CAKE) {
-                    application.registerReceiver(
-                        ConnectionChangeReceiver.getInstance(),
-                        IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION),
-                        ContextWrapper.RECEIVER_EXPORTED
-                    )
-                } else {
-                    application.registerReceiver(
-                        ConnectionChangeReceiver.getInstance(),
-                        IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION)
-                    )
-                }
-            }
             AnalyticsUtils.refreshMetadata(accountStore, siteStore)
             applicationOpenedDate = Date()
             // This stat is part of a funnel that provides critical information. Before making ANY modification to this

WordPress/src/main/java/org/wordpress/android/networking/ConnectionChangeReceiver.java

@@ -0,0 +1,79 @@
+package org.wordpress.android.networking
+
+import android.content.Context
+import android.net.ConnectivityManager
+import android.net.Network
+import android.os.Handler
+import android.os.HandlerThread
+import org.greenrobot.eventbus.EventBus
+import org.wordpress.android.util.AppLog
+import org.wordpress.android.util.AppLog.T
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * Global monitor for changes to the device's default network connectivity.
+ *
+ * Uses [ConnectivityManager.NetworkCallback] registered on a background [HandlerThread] rather than the
+ * deprecated CONNECTIVITY_ACTION broadcast. Because a NetworkCallback is not a broadcast it is not subject to
+ * background-broadcast ANR timeouts, and all connectivity work runs off the main thread. A
+ * [ConnectionChangeEvent] is posted on EventBus whenever the connected state changes; EventBus marshals the
+ * `onEventMainThread` subscribers back onto the main thread.
+ */
+@Singleton
+class NetworkConnectionMonitor @Inject constructor() {
+    private var started = false
+    private var wasConnected = false
+    private var isFirstCallback = true
+
+    private var connectivityManager: ConnectivityManager? = null
+    private var handlerThread: HandlerThread? = null
+    private var networkCallback: ConnectivityManager.NetworkCallback? = null
+
+    class ConnectionChangeEvent(val isConnected: Boolean)
+
+    @Synchronized
+    fun start(context: Context) {
+        if (started) return
+        val manager = context.applicationContext
+            .getSystemService(Context.CONNECTIVITY_SERVICE) as? ConnectivityManager ?: return
+        connectivityManager = manager
+
+        val thread = HandlerThread("NetworkConnectionMonitor").apply { start() }
+        handlerThread = thread
+
+        val callback = object : ConnectivityManager.NetworkCallback() {
+            override fun onAvailable(network: Network) = onConnectivityChanged(true)
+            override fun onLost(network: Network) = onConnectivityChanged(false)
+        }
+        networkCallback = callback
+
+        manager.registerDefaultNetworkCallback(callback, Handler(thread.looper))
+        started = true
+    }
+
+    @Synchronized
+    fun stop() {
+        if (!started) return
+        networkCallback?.let { connectivityManager?.unregisterNetworkCallback(it) }
+        handlerThread?.quitSafely()
+        networkCallback = null
+        handlerThread = null
+        connectivityManager = null
+        started = false
+    }
+
+    /**
+     * Called on the monitor's background thread. Posts a [ConnectionChangeEvent] on the first callback and
+     * whenever the connected state actually changes, so subscribers aren't spammed when a network's
+     * capabilities change without a change in availability.
+     */
+    private fun onConnectivityChanged(isConnected: Boolean) {
+        if (isFirstCallback || isConnected != wasConnected) {
+            isFirstCallback = false
+            wasConnected = isConnected
+            AppLog.i(T.UTILS, "Connection status changed, isConnected=$isConnected")
+            EventBus.getDefault().post(ConnectionChangeEvent(isConnected))
+        }
+    }
+}

WordPress/src/main/java/org/wordpress/android/networking/NetworkConnectionMonitor.kt

@@ -62,7 +62,7 @@
 import org.wordpress.android.inappupdate.IInAppUpdateManager;
 import org.wordpress.android.inappupdate.InAppUpdateListener;
 import org.wordpress.android.ui.accounts.login.LoginAnalyticsListener;
-import org.wordpress.android.networking.ConnectionChangeReceiver;
+import org.wordpress.android.networking.NetworkConnectionMonitor;
 import org.wordpress.android.push.GCMMessageHandler;
 import org.wordpress.android.push.GCMMessageService;
 import org.wordpress.android.push.GCMRegistrationScheduler;
@@ -1490,7 +1490,7 @@ public void onEventMainThread(NotificationEvents.NotificationsUnseenStatus event
 
     @SuppressWarnings("unused")
     @Subscribe(threadMode = ThreadMode.MAIN)
-    public void onEventMainThread(ConnectionChangeReceiver.ConnectionChangeEvent event) {
+    public void onEventMainThread(NetworkConnectionMonitor.ConnectionChangeEvent event) {
         updateConnectionBar(event.isConnected());
     }
 

WordPress/src/main/java/org/wordpress/android/ui/main/WPMainActivity.java

@@ -119,7 +119,7 @@ import org.wordpress.android.fluxc.store.bloggingprompts.BloggingPromptsStore
 import org.wordpress.android.fluxc.tools.FluxCImageLoader
 import org.wordpress.android.imageeditor.preview.PreviewImageFragment
 import org.wordpress.android.imageeditor.preview.PreviewImageFragment.Companion.EditImageData.InputData
-import org.wordpress.android.networking.ConnectionChangeReceiver.ConnectionChangeEvent
+import org.wordpress.android.networking.NetworkConnectionMonitor.ConnectionChangeEvent
 import org.wordpress.android.support.ZendeskHelper
 import org.wordpress.android.ui.ActivityId
 import org.wordpress.android.ui.ActivityLauncher

WordPress/src/main/java/org/wordpress/android/ui/posts/EditPostActivity.kt

@@ -22,7 +22,7 @@
 import org.wordpress.android.fluxc.store.SiteStore.OnSiteChanged;
 import org.wordpress.android.fluxc.store.SiteStore.OnSiteDeleted;
 import org.wordpress.android.fluxc.store.SiteStore.OnSiteRemoved;
-import org.wordpress.android.networking.ConnectionChangeReceiver;
+import org.wordpress.android.networking.NetworkConnectionMonitor;
 import org.wordpress.android.ui.main.BaseAppCompatActivity;
 import org.wordpress.android.util.SiteUtils;
 import org.wordpress.android.util.ToastUtils;
@@ -119,7 +119,7 @@ public boolean onOptionsItemSelected(@NonNull MenuItem item) {
 
     @SuppressWarnings("unused")
     @Subscribe(threadMode = ThreadMode.MAIN)
-    public void onEventMainThread(ConnectionChangeReceiver.ConnectionChangeEvent event) {
+    public void onEventMainThread(NetworkConnectionMonitor.ConnectionChangeEvent event) {
         SiteSettingsFragment siteSettingsFragment = getSettingsFragment();
         if (siteSettingsFragment != null) {
             if (!event.isConnected()) {

WordPress/src/main/java/org/wordpress/android/ui/prefs/BlogPreferencesActivity.java

@@ -69,7 +69,7 @@ import org.wordpress.android.models.ReaderPost
 import org.wordpress.android.models.ReaderPostDiscoverData
 import org.wordpress.android.models.ReaderTag
 import org.wordpress.android.models.ReaderTagType
-import org.wordpress.android.networking.ConnectionChangeReceiver.ConnectionChangeEvent
+import org.wordpress.android.networking.NetworkConnectionMonitor.ConnectionChangeEvent
 import org.wordpress.android.ui.ActionableEmptyView
 import org.wordpress.android.ui.ActivityLauncher
 import org.wordpress.android.ui.EmptyViewMessageType

WordPress/src/main/java/org/wordpress/android/ui/reader/ReaderPostListFragment.kt

@@ -16,7 +16,7 @@ import org.wordpress.android.R
 import org.wordpress.android.WordPress
 import org.wordpress.android.databinding.SuggestUsersActivityBinding
 import org.wordpress.android.fluxc.model.SiteModel
-import org.wordpress.android.networking.ConnectionChangeReceiver.ConnectionChangeEvent
+import org.wordpress.android.networking.NetworkConnectionMonitor.ConnectionChangeEvent
 import org.wordpress.android.ui.main.BaseAppCompatActivity
 import org.wordpress.android.ui.suggestion.FinishAttempt.NotExactlyOneAvailable
 import org.wordpress.android.ui.suggestion.FinishAttempt.OnlyOneAvailable

WordPress/src/main/java/org/wordpress/android/ui/suggestion/SuggestionActivity.kt

@@ -6,7 +6,7 @@ import androidx.lifecycle.ViewModel
 import org.wordpress.android.R
 import org.wordpress.android.analytics.AnalyticsTracker
 import org.wordpress.android.fluxc.model.SiteModel
-import org.wordpress.android.networking.ConnectionChangeReceiver.ConnectionChangeEvent
+import org.wordpress.android.networking.NetworkConnectionMonitor.ConnectionChangeEvent
 import org.wordpress.android.ui.suggestion.FinishAttempt.NotExactlyOneAvailable
 import org.wordpress.android.ui.suggestion.FinishAttempt.OnlyOneAvailable
 import org.wordpress.android.ui.suggestion.SuggestionType.Users

WordPress/src/main/java/org/wordpress/android/ui/suggestion/SuggestionViewModel.kt

@@ -18,7 +18,7 @@ import org.mockito.kotlin.whenever
 import org.wordpress.android.R
 import org.wordpress.android.analytics.AnalyticsTracker
 import org.wordpress.android.fluxc.model.SiteModel
-import org.wordpress.android.networking.ConnectionChangeReceiver.ConnectionChangeEvent
+import org.wordpress.android.networking.NetworkConnectionMonitor.ConnectionChangeEvent
 import org.wordpress.android.ui.suggestion.FinishAttempt.NotExactlyOneAvailable
 import org.wordpress.android.ui.suggestion.FinishAttempt.OnlyOneAvailable
 import org.wordpress.android.ui.suggestion.SuggestionType.Users