Inject executors for Realtime so async code can be tested. (#4375)

Allows the executor to be injected for testing. This came up testing Add updated params to the Realtime listener callback. #4339.
Prepares Realtime to integrate with Firebase Executors.

Author: danasilver

firebase-config/src/main/java/com/google/firebase/remoteconfig/RemoteConfigComponent.java

@@ -44,6 +44,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.atomic.AtomicReference;
 
 /**
@@ -84,7 +85,9 @@ public class RemoteConfigComponent {
       new HashMap<>();
 
   private final Context context;
+  // TODO: Consolidate executors.
   private final ExecutorService executorService;
+  private final ScheduledExecutorService scheduledExecutorService;
   private final FirebaseApp firebaseApp;
   private final FirebaseInstallationsApi firebaseInstallations;
   private final FirebaseABTesting firebaseAbt;
@@ -105,6 +108,7 @@ public class RemoteConfigComponent {
     this(
         context,
         Executors.newCachedThreadPool(),
+        Executors.newSingleThreadScheduledExecutor(),
         firebaseApp,
         firebaseInstallations,
         firebaseAbt,
@@ -117,6 +121,7 @@ public class RemoteConfigComponent {
   protected RemoteConfigComponent(
       Context context,
       ExecutorService executorService,
+      ScheduledExecutorService scheduledExecutorService,
       FirebaseApp firebaseApp,
       FirebaseInstallationsApi firebaseInstallations,
       FirebaseABTesting firebaseAbt,
@@ -128,6 +133,7 @@ protected RemoteConfigComponent(
     this.firebaseInstallations = firebaseInstallations;
     this.firebaseAbt = firebaseAbt;
     this.analyticsConnector = analyticsConnector;
+    this.scheduledExecutorService = scheduledExecutorService;
 
     this.appId = firebaseApp.getOptions().getApplicationId();
     GlobalBackgroundListener.ensureBackgroundListenerIsRegistered(context);
@@ -272,7 +278,8 @@ synchronized ConfigRealtimeHandler getRealtime(
         configFetchHandler,
         context,
         namespace,
-        executorService);
+        executorService,
+        scheduledExecutorService);
   }
 
   private ConfigGetParameterHandler getGetHandler(

firebase-config/src/main/java/com/google/firebase/remoteconfig/internal/ConfigAutoFetch.java

@@ -32,7 +32,6 @@
 import java.net.HttpURLConnection;
 import java.util.Random;
 import java.util.Set;
-import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import org.json.JSONException;
@@ -58,12 +57,13 @@ public ConfigAutoFetch(
       HttpURLConnection httpURLConnection,
       ConfigFetchHandler configFetchHandler,
       Set<ConfigUpdateListener> eventListeners,
-      ConfigUpdateListener retryCallback) {
+      ConfigUpdateListener retryCallback,
+      ScheduledExecutorService scheduledExecutorService) {
     this.httpURLConnection = httpURLConnection;
     this.configFetchHandler = configFetchHandler;
     this.eventListeners = eventListeners;
     this.retryCallback = retryCallback;
-    this.scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
+    this.scheduledExecutorService = scheduledExecutorService;
     this.random = new Random();
   }
 

firebase-config/src/main/java/com/google/firebase/remoteconfig/internal/ConfigRealtimeHandler.java

@@ -27,6 +27,7 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
 import java.util.concurrent.FutureTask;
+import java.util.concurrent.ScheduledExecutorService;
 
 public class ConfigRealtimeHandler {
 
@@ -42,14 +43,16 @@ public class ConfigRealtimeHandler {
   private final Context context;
   private final String namespace;
   private final ExecutorService executorService;
+  private final ScheduledExecutorService scheduledExecutorService;
 
   public ConfigRealtimeHandler(
       FirebaseApp firebaseApp,
       FirebaseInstallationsApi firebaseInstallations,
       ConfigFetchHandler configFetchHandler,
       Context context,
       String namespace,
-      ExecutorService executorService) {
+      ExecutorService executorService,
+      ScheduledExecutorService scheduledExecutorService) {
 
     this.listeners = new LinkedHashSet<>();
     this.realtimeHttpClientTask = null;
@@ -60,6 +63,7 @@ public ConfigRealtimeHandler(
     this.context = context;
     this.namespace = namespace;
     this.executorService = executorService;
+    this.scheduledExecutorService = scheduledExecutorService;
   }
 
   private synchronized boolean canCreateRealtimeHttpClientTask() {
@@ -92,7 +96,8 @@ private synchronized void beginRealtime() {
               configFetchHandler,
               context,
               namespace,
-              listeners);
+              listeners,
+              scheduledExecutorService);
       this.realtimeHttpClientTask =
           this.executorService.submit(
               new RealtimeHttpClientFutureTask(

firebase-config/src/main/java/com/google/firebase/remoteconfig/internal/ConfigRealtimeHttpClient.java

@@ -46,7 +46,6 @@
 import java.util.Map;
 import java.util.Random;
 import java.util.Set;
-import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.regex.Matcher;
@@ -93,11 +92,12 @@ public ConfigRealtimeHttpClient(
       ConfigFetchHandler configFetchHandler,
       Context context,
       String namespace,
-      Set<ConfigUpdateListener> listeners) {
+      Set<ConfigUpdateListener> listeners,
+      ScheduledExecutorService scheduledExecutorService) {
 
     this.listeners = listeners;
     this.httpURLConnection = null;
-    this.scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
+    this.scheduledExecutorService = scheduledExecutorService;
 
     // Retry parameters
     this.random = new Random();
@@ -303,7 +303,8 @@ public void onError(@NonNull FirebaseRemoteConfigException error) {
           }
         };
 
-    return new ConfigAutoFetch(httpURLConnection, configFetchHandler, listeners, retryCallback);
+    return new ConfigAutoFetch(
+        httpURLConnection, configFetchHandler, listeners, retryCallback, scheduledExecutorService);
   }
 
   // HTTP status code that the Realtime client should retry on.

firebase-config/src/test/java/com/google/firebase/remoteconfig/FirebaseRemoteConfigTest.java

@@ -82,6 +82,8 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -180,6 +182,9 @@ public final class FirebaseRemoteConfigTest {
 
   private FetchResponse firstFetchedContainerResponse;
 
+  private final ScheduledExecutorService scheduledExecutorService =
+      Executors.newSingleThreadScheduledExecutor();
+
   @Before
   public void setUp() throws Exception {
     DEFAULTS_MAP.put("first_default_key", "first_default_value");
@@ -304,15 +309,21 @@ public void onError(@NonNull FirebaseRemoteConfigException error) {
 
     listeners.add(listener);
     configAutoFetch =
-        new ConfigAutoFetch(mockHttpURLConnection, mockFetchHandler, listeners, mockRetryListener);
+        new ConfigAutoFetch(
+            mockHttpURLConnection,
+            mockFetchHandler,
+            listeners,
+            mockRetryListener,
+            scheduledExecutorService);
     configRealtimeHttpClient =
         new ConfigRealtimeHttpClient(
             firebaseApp,
             mockFirebaseInstallations,
             mockFetchHandler,
             context,
             "firebase",
-            listeners);
+            listeners,
+            scheduledExecutorService);
   }
 
   @Test

firebase-config/src/test/java/com/google/firebase/remoteconfig/RemoteConfigComponentTest.java

@@ -41,6 +41,8 @@
 import com.google.firebase.remoteconfig.internal.ConfigGetParameterHandler;
 import com.google.firebase.remoteconfig.internal.ConfigMetadataClient;
 import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -76,6 +78,7 @@ public class RemoteConfigComponentTest {
 
   private Context context;
   private ExecutorService directExecutor;
+  private ScheduledExecutorService scheduledExecutorService;
   private FirebaseApp defaultApp;
 
   @Before
@@ -84,6 +87,7 @@ public void setUp() {
 
     context = ApplicationProvider.getApplicationContext();
     directExecutor = MoreExecutors.newDirectExecutorService();
+    scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
 
     defaultApp = initializeFirebaseApp(context);
 
@@ -172,6 +176,7 @@ private RemoteConfigComponent getNewFrcComponent() {
     return new RemoteConfigComponent(
         context,
         directExecutor,
+        scheduledExecutorService,
         mockFirebaseApp,
         mockFirebaseInstallations,
         mockFirebaseAbt,
@@ -183,6 +188,7 @@ private RemoteConfigComponent getNewFrcComponentWithoutLoadingDefault() {
     return new RemoteConfigComponent(
         context,
         directExecutor,
+        scheduledExecutorService,
         mockFirebaseApp,
         mockFirebaseInstallations,
         mockFirebaseAbt,