Use Dagger for dependency injection in Sessions (#6745)

Author: mrober

firebase-sessions/CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+* [changed] Use Dagger for dependency injection
 * [changed] Updated datastore dependency to `1.1.3` to
   fix [CVE-2024-7254](https://github.com/advisories/GHSA-735f-pc8j-v9w8).
 

firebase-sessions/firebase-sessions.gradle.kts

@@ -18,6 +18,7 @@
 
 plugins {
   id("firebase-library")
+  id("firebase-vendor")
   id("kotlin-android")
   id("kotlin-kapt")
 }
@@ -67,12 +68,18 @@ dependencies {
     exclude(group = "com.google.firebase", module = "firebase-common")
     exclude(group = "com.google.firebase", module = "firebase-components")
   }
-  implementation("com.google.android.datatransport:transport-api:3.2.0")
+
   api("com.google.firebase:firebase-annotations:16.2.0")
   api("com.google.firebase:firebase-encoders:17.0.0")
   api("com.google.firebase:firebase-encoders-json:18.0.1")
+
+  implementation("com.google.android.datatransport:transport-api:3.2.0")
+  implementation(libs.javax.inject)
   implementation(libs.androidx.annotation)
   implementation(libs.androidx.datastore.preferences)
+
+  vendor(libs.dagger.dagger) { exclude(group = "javax.inject", module = "javax.inject") }
+
   compileOnly(libs.errorprone.annotations)
 
   runtimeOnly("com.google.firebase:firebase-installations:18.0.0") {
@@ -85,6 +92,7 @@ dependencies {
   }
 
   kapt(project(":encoders:firebase-encoders-processor"))
+  kapt(libs.dagger.compiler)
 
   testImplementation(project(":integ-testing")) {
     exclude(group = "com.google.firebase", module = "firebase-common")

firebase-sessions/src/main/kotlin/com/google/firebase/sessions/EventGDTLogger.kt

@@ -21,6 +21,8 @@ import com.google.android.datatransport.Encoding
 import com.google.android.datatransport.Event
 import com.google.android.datatransport.TransportFactory
 import com.google.firebase.inject.Provider
+import javax.inject.Inject
+import javax.inject.Singleton
 
 /**
  * The [EventGDTLoggerInterface] is for testing purposes so that we can mock EventGDTLogger in other
@@ -38,19 +40,17 @@ internal fun interface EventGDTLoggerInterface {
  *
  * @hide
  */
-internal class EventGDTLogger(private val transportFactoryProvider: Provider<TransportFactory>) :
+@Singleton
+internal class EventGDTLogger
+@Inject
+constructor(private val transportFactoryProvider: Provider<TransportFactory>) :
   EventGDTLoggerInterface {
 
   // Logs a [SessionEvent] to FireLog
   override fun log(sessionEvent: SessionEvent) {
     transportFactoryProvider
       .get()
-      .getTransport(
-        AQS_LOG_SOURCE,
-        SessionEvent::class.java,
-        Encoding.of("json"),
-        this::encode,
-      )
+      .getTransport(AQS_LOG_SOURCE, SessionEvent::class.java, Encoding.of("json"), this::encode)
       .send(Event.ofData(sessionEvent))
   }
 

firebase-sessions/src/main/kotlin/com/google/firebase/sessions/FirebaseSessions.kt

@@ -20,18 +20,24 @@ import android.app.Application
 import android.util.Log
 import com.google.firebase.Firebase
 import com.google.firebase.FirebaseApp
+import com.google.firebase.annotations.concurrent.Background
 import com.google.firebase.app
 import com.google.firebase.sessions.api.FirebaseSessionsDependencies
 import com.google.firebase.sessions.settings.SessionsSettings
+import javax.inject.Inject
+import javax.inject.Singleton
 import kotlin.coroutines.CoroutineContext
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.launch
 
 /** Responsible for initializing AQS */
-internal class FirebaseSessions(
+@Singleton
+internal class FirebaseSessions
+@Inject
+constructor(
   private val firebaseApp: FirebaseApp,
   private val settings: SessionsSettings,
-  backgroundDispatcher: CoroutineContext,
+  @Background backgroundDispatcher: CoroutineContext,
   lifecycleServiceBinder: SessionLifecycleServiceBinder,
 ) {
 

firebase-sessions/src/main/kotlin/com/google/firebase/sessions/FirebaseSessionsComponent.kt

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2025 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.sessions
+
+import android.content.Context
+import com.google.android.datatransport.TransportFactory
+import com.google.firebase.FirebaseApp
+import com.google.firebase.annotations.concurrent.Background
+import com.google.firebase.annotations.concurrent.Blocking
+import com.google.firebase.inject.Provider
+import com.google.firebase.installations.FirebaseInstallationsApi
+import com.google.firebase.sessions.settings.SessionsSettings
+import dagger.Binds
+import dagger.BindsInstance
+import dagger.Component
+import dagger.Module
+import dagger.Provides
+import javax.inject.Singleton
+import kotlin.coroutines.CoroutineContext
+
+/** Dagger component to provide [FirebaseSessions] and its dependencies. */
+@Singleton
+@Component(modules = [FirebaseSessionsComponent.MainModule::class])
+internal interface FirebaseSessionsComponent {
+  val firebaseSessions: FirebaseSessions
+
+  val sessionDatastore: SessionDatastore
+  val sessionFirelogPublisher: SessionFirelogPublisher
+  val sessionGenerator: SessionGenerator
+  val sessionsSettings: SessionsSettings
+
+  @Component.Builder
+  interface Builder {
+    @BindsInstance fun appContext(appContext: Context): Builder
+
+    @BindsInstance
+    fun backgroundDispatcher(@Background backgroundDispatcher: CoroutineContext): Builder
+
+    @BindsInstance fun blockingDispatcher(@Blocking blockingDispatcher: CoroutineContext): Builder
+
+    @BindsInstance fun firebaseApp(firebaseApp: FirebaseApp): Builder
+
+    @BindsInstance
+    fun firebaseInstallationsApi(firebaseInstallationsApi: FirebaseInstallationsApi): Builder
+
+    @BindsInstance
+    fun transportFactoryProvider(transportFactoryProvider: Provider<TransportFactory>): Builder
+
+    fun build(): FirebaseSessionsComponent
+  }
+
+  @Module
+  interface MainModule {
+    @Binds @Singleton fun eventGDTLoggerInterface(impl: EventGDTLogger): EventGDTLoggerInterface
+
+    @Binds @Singleton fun sessionDatastore(impl: SessionDatastoreImpl): SessionDatastore
+
+    @Binds
+    @Singleton
+    fun sessionFirelogPublisher(impl: SessionFirelogPublisherImpl): SessionFirelogPublisher
+
+    @Binds
+    @Singleton
+    fun sessionLifecycleServiceBinder(
+      impl: SessionLifecycleServiceBinderImpl
+    ): SessionLifecycleServiceBinder
+
+    companion object {
+      @Provides @Singleton fun sessionGenerator() = SessionGenerator(timeProvider = WallClock)
+    }
+  }
+}

firebase-sessions/src/main/kotlin/com/google/firebase/sessions/FirebaseSessionsRegistrar.kt

@@ -16,6 +16,7 @@
 
 package com.google.firebase.sessions
 
+import android.content.Context
 import androidx.annotation.Keep
 import com.google.android.datatransport.TransportFactory
 import com.google.firebase.FirebaseApp
@@ -28,7 +29,6 @@ import com.google.firebase.components.Qualified.qualified
 import com.google.firebase.components.Qualified.unqualified
 import com.google.firebase.installations.FirebaseInstallationsApi
 import com.google.firebase.platforminfo.LibraryVersionComponent
-import com.google.firebase.sessions.settings.SessionsSettings
 import kotlinx.coroutines.CoroutineDispatcher
 
 /**
@@ -42,87 +42,41 @@ internal class FirebaseSessionsRegistrar : ComponentRegistrar {
     listOf(
       Component.builder(FirebaseSessions::class.java)
         .name(LIBRARY_NAME)
-        .add(Dependency.required(firebaseApp))
-        .add(Dependency.required(sessionsSettings))
-        .add(Dependency.required(backgroundDispatcher))
-        .add(Dependency.required(sessionLifecycleServiceBinder))
-        .factory { container ->
-          FirebaseSessions(
-            container[firebaseApp],
-            container[sessionsSettings],
-            container[backgroundDispatcher],
-            container[sessionLifecycleServiceBinder],
-          )
-        }
+        .add(Dependency.required(firebaseSessionsComponent))
+        .factory { container -> container[firebaseSessionsComponent].firebaseSessions }
         .eagerInDefaultApp()
         .build(),
-      Component.builder(SessionGenerator::class.java)
-        .name("session-generator")
-        .factory { SessionGenerator(timeProvider = WallClock) }
-        .build(),
-      Component.builder(SessionFirelogPublisher::class.java)
-        .name("session-publisher")
-        .add(Dependency.required(firebaseApp))
-        .add(Dependency.required(firebaseInstallationsApi))
-        .add(Dependency.required(sessionsSettings))
-        .add(Dependency.requiredProvider(transportFactory))
+      Component.builder(FirebaseSessionsComponent::class.java)
+        .name("fire-sessions-component")
+        .add(Dependency.required(appContext))
         .add(Dependency.required(backgroundDispatcher))
-        .factory { container ->
-          SessionFirelogPublisherImpl(
-            container[firebaseApp],
-            container[firebaseInstallationsApi],
-            container[sessionsSettings],
-            EventGDTLogger(container.getProvider(transportFactory)),
-            container[backgroundDispatcher],
-          )
-        }
-        .build(),
-      Component.builder(SessionsSettings::class.java)
-        .name("sessions-settings")
-        .add(Dependency.required(firebaseApp))
         .add(Dependency.required(blockingDispatcher))
-        .add(Dependency.required(backgroundDispatcher))
-        .add(Dependency.required(firebaseInstallationsApi))
-        .factory { container ->
-          SessionsSettings(
-            container[firebaseApp],
-            container[blockingDispatcher],
-            container[backgroundDispatcher],
-            container[firebaseInstallationsApi],
-          )
-        }
-        .build(),
-      Component.builder(SessionDatastore::class.java)
-        .name("sessions-datastore")
         .add(Dependency.required(firebaseApp))
-        .add(Dependency.required(backgroundDispatcher))
+        .add(Dependency.required(firebaseInstallationsApi))
+        .add(Dependency.requiredProvider(transportFactory))
         .factory { container ->
-          SessionDatastoreImpl(
-            container[firebaseApp].applicationContext,
-            container[backgroundDispatcher],
-          )
+          DaggerFirebaseSessionsComponent.builder()
+            .appContext(container[appContext])
+            .backgroundDispatcher(container[backgroundDispatcher])
+            .blockingDispatcher(container[blockingDispatcher])
+            .firebaseApp(container[firebaseApp])
+            .firebaseInstallationsApi(container[firebaseInstallationsApi])
+            .transportFactoryProvider(container.getProvider(transportFactory))
+            .build()
         }
         .build(),
-      Component.builder(SessionLifecycleServiceBinder::class.java)
-        .name("sessions-service-binder")
-        .add(Dependency.required(firebaseApp))
-        .factory { container -> SessionLifecycleServiceBinderImpl(container[firebaseApp]) }
-        .build(),
       LibraryVersionComponent.create(LIBRARY_NAME, BuildConfig.VERSION_NAME),
     )
 
   private companion object {
-    private const val LIBRARY_NAME = "fire-sessions"
+    const val LIBRARY_NAME = "fire-sessions"
 
-    private val firebaseApp = unqualified(FirebaseApp::class.java)
-    private val firebaseInstallationsApi = unqualified(FirebaseInstallationsApi::class.java)
-    private val backgroundDispatcher =
-      qualified(Background::class.java, CoroutineDispatcher::class.java)
-    private val blockingDispatcher =
-      qualified(Blocking::class.java, CoroutineDispatcher::class.java)
-    private val transportFactory = unqualified(TransportFactory::class.java)
-    private val sessionsSettings = unqualified(SessionsSettings::class.java)
-    private val sessionLifecycleServiceBinder =
-      unqualified(SessionLifecycleServiceBinder::class.java)
+    val appContext = unqualified(Context::class.java)
+    val firebaseApp = unqualified(FirebaseApp::class.java)
+    val firebaseInstallationsApi = unqualified(FirebaseInstallationsApi::class.java)
+    val backgroundDispatcher = qualified(Background::class.java, CoroutineDispatcher::class.java)
+    val blockingDispatcher = qualified(Blocking::class.java, CoroutineDispatcher::class.java)
+    val transportFactory = unqualified(TransportFactory::class.java)
+    val firebaseSessionsComponent = unqualified(FirebaseSessionsComponent::class.java)
   }
 }

firebase-sessions/src/main/kotlin/com/google/firebase/sessions/SessionDatastore.kt

@@ -26,10 +26,13 @@ import androidx.datastore.preferences.core.emptyPreferences
 import androidx.datastore.preferences.core.stringPreferencesKey
 import androidx.datastore.preferences.preferencesDataStore
 import com.google.firebase.Firebase
+import com.google.firebase.annotations.concurrent.Background
 import com.google.firebase.app
 import com.google.firebase.sessions.ProcessDetailsProvider.getProcessName
 import java.io.IOException
 import java.util.concurrent.atomic.AtomicReference
+import javax.inject.Inject
+import javax.inject.Singleton
 import kotlin.coroutines.CoroutineContext
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.Flow
@@ -53,13 +56,16 @@ internal interface SessionDatastore {
 
   companion object {
     val instance: SessionDatastore
-      get() = Firebase.app[SessionDatastore::class.java]
+      get() = Firebase.app[FirebaseSessionsComponent::class.java].sessionDatastore
   }
 }
 
-internal class SessionDatastoreImpl(
-  private val context: Context,
-  private val backgroundDispatcher: CoroutineContext,
+@Singleton
+internal class SessionDatastoreImpl
+@Inject
+constructor(
+  private val appContext: Context,
+  @Background private val backgroundDispatcher: CoroutineContext,
 ) : SessionDatastore {
 
   /** Most recent session from datastore is updated asynchronously whenever it changes */
@@ -70,7 +76,7 @@ internal class SessionDatastoreImpl(
   }
 
   private val firebaseSessionDataFlow: Flow<FirebaseSessionsData> =
-    context.dataStore.data
+    appContext.dataStore.data
       .catch { exception ->
         Log.e(TAG, "Error reading stored session data.", exception)
         emit(emptyPreferences())
@@ -86,24 +92,19 @@ internal class SessionDatastoreImpl(
   override fun updateSessionId(sessionId: String) {
     CoroutineScope(backgroundDispatcher).launch {
       try {
-        context.dataStore.edit { preferences ->
+        appContext.dataStore.edit { preferences ->
           preferences[FirebaseSessionDataKeys.SESSION_ID] = sessionId
         }
       } catch (e: IOException) {
-        Log.w(
-          TAG,
-          "Failed to update session Id: $e",
-        )
+        Log.w(TAG, "Failed to update session Id: $e")
       }
     }
   }
 
   override fun getCurrentSessionId() = currentSessionFromDatastore.get()?.sessionId
 
   private fun mapSessionsData(preferences: Preferences): FirebaseSessionsData =
-    FirebaseSessionsData(
-      preferences[FirebaseSessionDataKeys.SESSION_ID],
-    )
+    FirebaseSessionsData(preferences[FirebaseSessionDataKeys.SESSION_ID])
 
   private companion object {
     private const val TAG = "FirebaseSessionsRepo"