Merging from Master. Also fixing the merge issues with #2546

Author: ramanpreetSinghKhinda

firebase-perf/src/main/java/com/google/firebase/perf/FirebasePerfRegistrar.java

@@ -52,12 +52,14 @@ public List<Component<?>> getComponents() {
             .add(Dependency.required(FirebaseInstallationsApi.class))
             .add(Dependency.requiredProvider(TransportFactory.class))
             .factory(FirebasePerfRegistrar::providesFirebasePerformance)
-            // Since the SDK is eager(auto starts at app start), we use "lazy" dependency for some
-            // components that are not required during initialization so as not to force initialize
-            // them at app startup (refer
-            // https://github.com/google/guice/wiki/InjectingProviders#providers-for-lazy-loading).
-            .eagerInDefaultApp()
             .build(),
+        /**
+         * Fireperf SDK is lazily by {@link FirebasePerformanceInitializer} during {@link
+         * com.google.firebase.perf.application.AppStateMonitor#onActivityResumed(Activity)}. we use
+         * "lazy" dependency for some components that are not required during initialization so as
+         * not to force initialize them at app startup (refer
+         * https://github.com/google/guice/wiki/InjectingProviders#providers-for-lazy-loading)*
+         */
         LibraryVersionComponent.create("fire-perf", BuildConfig.VERSION_NAME));
   }
 

firebase-perf/src/main/java/com/google/firebase/perf/FirebasePerformanceInitializer.java

@@ -0,0 +1,33 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.firebase.perf;
+
+import com.google.firebase.perf.application.AppStateMonitor;
+
+/**
+ * FirebasePerformanceInitializer to initialize FirebasePerformance during app cold start
+ *
+ * @hide
+ */
+/** @hide */
+public final class FirebasePerformanceInitializer implements AppStateMonitor.AppColdStartCallback {
+
+  /** @hide */
+  @Override
+  public void onAppColdStart() {
+    // Initialize FirebasePerformance when app cold starts.
+    FirebasePerformance.getInstance();
+  }
+}

firebase-perf/src/main/java/com/google/firebase/perf/application/AppStateMonitor.java

@@ -64,6 +64,7 @@ public class AppStateMonitor implements ActivityLifecycleCallbacks {
   private final WeakHashMap<Activity, Trace> activityToScreenTraceMap = new WeakHashMap<>();
   private final Map<String, Long> metricToCountMap = new HashMap<>();
   private final Set<WeakReference<AppStateCallback>> appStateSubscribers = new HashSet<>();
+  private Set<AppColdStartCallback> appColdStartSubscribers = new HashSet<>();
 
   /* Count for TRACE_STARTED_NOT_STOPPED */
   private final AtomicInteger tsnsCount = new AtomicInteger(0);
@@ -208,6 +209,7 @@ public synchronized void onActivityResumed(Activity activity) {
       updateAppState(ApplicationProcessState.FOREGROUND);
       if (isColdStart) {
         // case 1: app startup.
+        sendAppColdStartUpdate();
         isColdStart = false;
       } else {
         // case 2: app switch from background to foreground.
@@ -234,32 +236,45 @@ public ApplicationProcessState getAppState() {
   }
 
   /**
-   * Register a client to receive app state update.
+   * Register a subscriber to receive app state update.
    *
    * @param client an AppStateCallback instance.
    * @hide
    */
   /** @hide */
-  public void registerForAppState(WeakReference<AppStateCallback> client) {
+  public void registerForAppState(WeakReference<AppStateCallback> subscriber) {
     synchronized (appStateSubscribers) {
-      appStateSubscribers.add(client);
+      appStateSubscribers.add(subscriber);
     }
   }
 
   /**
-   * Unregister the client to stop receiving app state update.
+   * Unregister the subscriber to stop receiving app state update.
    *
-   * @param client an AppStateCallback instance.
+   * @param subscriber an AppStateCallback instance.
+   * @hide
+   */
+  /** @hide */
+  public void unregisterForAppState(WeakReference<AppStateCallback> subscriber) {
+    synchronized (appStateSubscribers) {
+      appStateSubscribers.remove(subscriber);
+    }
+  }
+
+  /**
+   * Register a subscriber to receive app cold start update.
+   *
+   * @param subscriber the {@link AppColdStartCallback} instance.
    * @hide
    */
   /** @hide */
-  public void unregisterForAppState(WeakReference<AppStateCallback> client) {
+  public void registerForAppColdStart(AppColdStartCallback subscriber) {
     synchronized (appStateSubscribers) {
-      appStateSubscribers.remove(client);
+      appColdStartSubscribers.add(subscriber);
     }
   }
 
-  /** Send update state update to registered clients. */
+  /** Send update state update to registered subscribers. */
   private void updateAppState(ApplicationProcessState newState) {
     currentAppState = newState;
     synchronized (appStateSubscribers) {
@@ -277,6 +292,18 @@ private void updateAppState(ApplicationProcessState newState) {
     }
   }
 
+  /** Send cold start update to registered subscribers. */
+  private void sendAppColdStartUpdate() {
+    synchronized (appStateSubscribers) {
+      for (Iterator<AppColdStartCallback> i = appColdStartSubscribers.iterator(); i.hasNext(); ) {
+        AppColdStartCallback callback = i.next();
+        if (callback != null) {
+          callback.onAppColdStart();
+        }
+      }
+    }
+  }
+
   /**
    * Return app is in foreground or not.
    *
@@ -426,7 +453,7 @@ private boolean hasFrameMetricsAggregatorClass() {
   }
 
   /**
-   * An interface to be implemented by clients which needs to receive app state update.
+   * An interface to be implemented by subscribers which needs to receive app state update.
    *
    * @hide
    */
@@ -437,6 +464,15 @@ public static interface AppStateCallback {
     public void onUpdateAppState(ApplicationProcessState newState);
   }
 
+  /**
+   * An interface to be implemented by subscribers which needs to receive app cold start update.
+   *
+   * @hide
+   */
+  public static interface AppColdStartCallback {
+    public void onAppColdStart();
+  }
+
   /**
    * Screen trace name is prefix "_st_" concatenates with Activity's class name.
    *

firebase-perf/src/main/java/com/google/firebase/perf/provider/FirebasePerfProvider.java

@@ -28,6 +28,7 @@
 import androidx.annotation.Nullable;
 import com.google.android.gms.common.internal.Preconditions;
 import com.google.android.gms.common.util.VisibleForTesting;
+import com.google.firebase.perf.FirebasePerformanceInitializer;
 import com.google.firebase.perf.application.AppStateMonitor;
 import com.google.firebase.perf.config.ConfigResolver;
 import com.google.firebase.perf.metrics.AppStartTrace;
@@ -62,7 +63,10 @@ public void attachInfo(Context context, ProviderInfo info) {
     ConfigResolver configResolver = ConfigResolver.getInstance();
     configResolver.setContentProviderContext(getContext());
 
-    AppStateMonitor.getInstance().registerActivityLifecycleCallbacks(getContext());
+    AppStateMonitor appStateMonitor = AppStateMonitor.getInstance();
+    appStateMonitor.registerActivityLifecycleCallbacks(getContext());
+    appStateMonitor.registerForAppColdStart(new FirebasePerformanceInitializer());
+
     AppStartTrace appStartTrace = AppStartTrace.getInstance();
     appStartTrace.registerActivityLifecycleCallbacks(getContext());
 

firebase-perf/src/main/java/com/google/firebase/perf/session/PerfSession.java

@@ -20,7 +20,6 @@
 import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
 import com.google.firebase.perf.config.ConfigResolver;
-import com.google.firebase.perf.logging.AndroidLogger;
 import com.google.firebase.perf.util.Clock;
 import com.google.firebase.perf.util.Timer;
 import com.google.firebase.perf.v1.SessionVerbosity;
@@ -51,11 +50,6 @@ public static PerfSession create() {
     PerfSession session = new PerfSession(sessionId, new Clock());
     session.setGaugeAndEventCollectionEnabled(shouldCollectGaugesAndEvents());
 
-    AndroidLogger.getInstance()
-        .debug(
-            "Creating a new %s Session: %s",
-            session.isVerbose() ? "Verbose" : "Non Verbose", sessionId);
-
     return session;
   }
 

firebase-perf/src/main/java/com/google/firebase/perf/transport/TransportManager.java

@@ -108,7 +108,6 @@ public class TransportManager implements AppStateCallback {
       new ConcurrentLinkedQueue<>();
 
   private final AtomicBoolean isTransportInitialized = new AtomicBoolean(false);
-  private final ApplicationInfo.Builder applicationInfoBuilder;
 
   private FirebaseApp firebaseApp;
   @Nullable private FirebasePerformance firebasePerformance;
@@ -120,6 +119,7 @@ public class TransportManager implements AppStateCallback {
   private ConfigResolver configResolver;
   private RateLimiter rateLimiter;
   private AppStateMonitor appStateMonitor;
+  private ApplicationInfo.Builder applicationInfoBuilder;
 
   private boolean isForegroundState = false;
 
@@ -136,8 +136,6 @@ private TransportManager() {
             TimeUnit.SECONDS,
             new LinkedBlockingQueue<>());
 
-    this.applicationInfoBuilder = ApplicationInfo.newBuilder();
-
     cacheMap = new ConcurrentHashMap<>();
     cacheMap.put(KEY_AVAILABLE_TRACES_FOR_CACHING, MAX_TRACE_METRICS_CACHE_SIZE);
     cacheMap.put(
@@ -219,6 +217,7 @@ private void syncInit() {
   private void finishInitialization() {
     appStateMonitor.registerForAppState(new WeakReference<>(instance));
 
+    applicationInfoBuilder = ApplicationInfo.newBuilder();
     applicationInfoBuilder
         .setGoogleAppId(firebaseApp.getOptions().getApplicationId())
         .setAndroidAppInfo(

firebase-perf/src/test/java/com/google/firebase/perf/FirebasePerfRegistrarTest.java

@@ -48,6 +48,6 @@ public void testGetComponents() {
             Dependency.required(FirebaseInstallationsApi.class),
             Dependency.requiredProvider(TransportFactory.class));
 
-    assertThat(firebasePerfComponent.isEagerInDefaultApp()).isTrue();
+    assertThat(firebasePerfComponent.isLazy()).isTrue();
   }
 }

firebase-perf/src/test/java/com/google/firebase/perf/FirebasePerformanceTestBase.java

@@ -48,19 +48,19 @@ public class FirebasePerformanceTestBase {
   protected static final String FAKE_FIREBASE_DB_URL = "https://fir-perftestapp.firebaseio.com";
   protected static final String FAKE_FIREBASE_PROJECT_ID = "fir-perftestapp";
 
-  protected Context context;
+  protected Context appContext;
 
   @Before
   public void setUpFirebaseApp() {
-    context = ApplicationProvider.getApplicationContext();
+    appContext = ApplicationProvider.getApplicationContext();
     FirebaseOptions options =
         new FirebaseOptions.Builder()
             .setApplicationId(FAKE_FIREBASE_APPLICATION_ID)
             .setApiKey(FAKE_FIREBASE_API_KEY)
             .setDatabaseUrl(FAKE_FIREBASE_DB_URL)
             .setProjectId(FAKE_FIREBASE_PROJECT_ID)
             .build();
-    FirebaseApp.initializeApp(context, options);
+    FirebaseApp.initializeApp(appContext, options);
   }
 
   @After