Use AQS for Firebase Performance sessions.

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

@@ -20,6 +20,7 @@
 import com.google.firebase.StartupTime;
 import com.google.firebase.perf.application.AppStateMonitor;
 import com.google.firebase.perf.config.ConfigResolver;
+import com.google.firebase.perf.logging.AndroidLogger;
 import com.google.firebase.perf.metrics.AppStartTrace;
 import com.google.firebase.perf.session.SessionManager;
 import java.util.concurrent.Executor;
@@ -51,12 +52,11 @@ public FirebasePerfEarly(
       uiExecutor.execute(new AppStartTrace.StartFromBackgroundRunnable(appStartTrace));
     }
 
-    // TODO: Bring back Firebase Sessions dependency to watch for updates to sessions.
-
     // In the case of cold start, we create a session and start collecting gauges as early as
     // possible.
     // There is code in SessionManager that prevents us from resetting the session twice in case
     // of app cold start.
+    AndroidLogger.getInstance().debug("Initializing Gauge Collection");
     SessionManager.getInstance().initializeGaugeCollection();
   }
 }

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

@@ -50,7 +50,6 @@ public class FirebasePerfRegistrar implements ComponentRegistrar {
   private static final String EARLY_LIBRARY_NAME = "fire-perf-early";
 
   static {
-    // Add Firebase Performance as a dependency of Sessions when this class is loaded into memory.
     FirebaseSessionsDependencies.addDependency(SessionSubscriber.Name.PERFORMANCE);
   }
 

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

@@ -170,6 +170,10 @@ public static FirebasePerformance getInstance() {
       return;
     }
 
+    // Prioritize registering the FirebaseSession dependency to have the session
+    // `setApplicationContext`.
+    FirebaseSessionsDependencies.register(
+        FirebasePerformanceSessionSubscriber.Companion.getInstance());
     TransportManager.getInstance()
         .initialize(firebaseApp, firebaseInstallationsApi, transportFactoryProvider);
 
@@ -193,6 +197,9 @@ public static FirebasePerformance getInstance() {
               ConsoleUrlGenerator.generateDashboardUrl(
                   firebaseApp.getOptions().getProjectId(), appContext.getPackageName())));
     }
+
+    SessionManagerKt sessionSubscriber = new SessionManagerKt(isPerformanceCollectionEnabled());
+    FirebaseSessionsDependencies.register(sessionSubscriber);
   }
 
   /**

firebase-perf/src/main/java/com/google/firebase/perf/config/ConfigResolver.java

@@ -116,7 +116,7 @@ public void setMetadataBundle(ImmutableBundle bundle) {
   /** Default API to call for whether performance monitoring is currently silent. */
   public boolean isPerformanceMonitoringEnabled() {
     Boolean isPerformanceCollectionEnabled = getIsPerformanceCollectionEnabled();
-    return (isPerformanceCollectionEnabled == null || isPerformanceCollectionEnabled == true)
+    return (isPerformanceCollectionEnabled == null || isPerformanceCollectionEnabled)
         && getIsServiceCollectionEnabled();
   }
 
@@ -131,7 +131,7 @@ public Boolean getIsPerformanceCollectionEnabled() {
     // return developer config.
     // 4. Else, return null. Because Firebase Performance will read highlevel Firebase flag in this
     // case.
-    if (getIsPerformanceCollectionDeactivated()) {
+    if (Boolean.TRUE.equals(getIsPerformanceCollectionDeactivated())) {
       // 1. If developer has deactivated Firebase Performance in Manifest, return false.
       return false;
     }
@@ -186,7 +186,7 @@ public void setIsPerformanceCollectionEnabled(Boolean isEnabled) {
     // 2. Otherwise, save this configuration in device cache.
 
     // If collection is deactivated, skip the action to save user configuration.
-    if (getIsPerformanceCollectionDeactivated()) {
+    if (Boolean.TRUE.equals(getIsPerformanceCollectionDeactivated())) {
       return;
     }
 

firebase-perf/src/main/java/com/google/firebase/perf/session/FirebasePerformanceSessionSubscriber.kt

@@ -1,46 +1,58 @@
-/*
- * 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.perf.session
 
+import com.google.firebase.perf.config.ConfigResolver
+import com.google.firebase.perf.logging.AndroidLogger
 import com.google.firebase.perf.session.gauges.GaugeManager
-import com.google.firebase.perf.v1.ApplicationProcessState
 import com.google.firebase.sessions.api.SessionSubscriber
-import java.util.UUID
 
-class FirebasePerformanceSessionSubscriber(override val isDataCollectionEnabled: Boolean) :
+class FirebasePerformanceSessionSubscriber(private val dataCollectionEnabled: Boolean) :
   SessionSubscriber {
+  private val perfSessionToAqs: MutableMap<String, SessionSubscriber.SessionDetails?> =
+    mutableMapOf()
+
+  override val isDataCollectionEnabled: Boolean
+    get() = dataCollectionEnabled
 
-  override val sessionSubscriberName: SessionSubscriber.Name = SessionSubscriber.Name.PERFORMANCE
+  override val sessionSubscriberName: SessionSubscriber.Name
+    get() = SessionSubscriber.Name.PERFORMANCE
 
   override fun onSessionChanged(sessionDetails: SessionSubscriber.SessionDetails) {
-    val currentPerfSession = SessionManager.getInstance().perfSession()
-
-    // A [PerfSession] was created before a session was started.
-    if (currentPerfSession.aqsSessionId() == null) {
-      currentPerfSession.setAQSId(sessionDetails)
-      GaugeManager.getInstance()
-        .logGaugeMetadata(currentPerfSession.aqsSessionId(), ApplicationProcessState.FOREGROUND)
-      return
+    AndroidLogger.getInstance().debug("AQS Session Changed: $sessionDetails")
+    val currentInternalSessionId = SessionManager.getInstance().perfSession().internalSessionId
+
+    // There can be situations where a new [PerfSession] was created, but an AQS wasn't
+    // available (during cold start).
+    if (perfSessionToAqs[currentInternalSessionId] == null) {
+      perfSessionToAqs[currentInternalSessionId] = sessionDetails
+    } else {
+      val newSession = PerfSession.createNewSession()
+      SessionManager.getInstance().updatePerfSession(newSession)
+      perfSessionToAqs[newSession.internalSessionId] = sessionDetails
     }
 
-    val updatedSession = PerfSession.createWithId(UUID.randomUUID().toString())
-    updatedSession.setAQSId(sessionDetails)
-    SessionManager.getInstance().updatePerfSession(updatedSession)
-    GaugeManager.getInstance()
-      .logGaugeMetadata(updatedSession.aqsSessionId(), ApplicationProcessState.FOREGROUND)
+    // Always log GaugeMetadata when a session changes.
+    GaugeManager.getInstance().logGaugeMetadata(sessionDetails.sessionId)
+  }
+
+  fun reportPerfSession(perfSessionId: String) {
+    perfSessionToAqs[perfSessionId] = null
+  }
+
+  fun getAqsMappedToPerfSession(perfSessionId: String): String {
+    AndroidLogger.getInstance()
+      .debug("AQS for perf session $perfSessionId is ${perfSessionToAqs[perfSessionId]?.sessionId}")
+    return perfSessionToAqs[perfSessionId]?.sessionId ?: perfSessionId
+  }
+
+  fun clearSessionForTest() {
+    perfSessionToAqs.clear()
+  }
+
+  companion object {
+    val instance: FirebasePerformanceSessionSubscriber by lazy {
+      FirebasePerformanceSessionSubscriber(
+        ConfigResolver.getInstance().isPerformanceMonitoringEnabled
+      )
+    }
   }
 }

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

@@ -25,11 +25,13 @@
 import com.google.firebase.perf.v1.SessionVerbosity;
 import com.google.firebase.sessions.api.SessionSubscriber;
 import java.util.List;
+import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 
 /** Details of a session including a unique Id and related information. */
 public class PerfSession implements Parcelable {
 
+  private static final String SESSION_ID_PREFIX = "fireperf-session";
   private final String sessionId;
   private final Timer creationTime;
   @Nullable private String aqsSessionId;
@@ -39,11 +41,10 @@ public class PerfSession implements Parcelable {
   /*
    * Creates a PerfSession object and decides what metrics to collect.
    */
-  public static PerfSession createWithId(@NonNull String sessionId) {
-    String prunedSessionId = sessionId.replace("-", "");
+  public static PerfSession createNewSession() {
+    String prunedSessionId = SESSION_ID_PREFIX + UUID.randomUUID().toString().replace("-", "");
     PerfSession session = new PerfSession(prunedSessionId, new Clock());
     session.setGaugeAndEventCollectionEnabled(shouldCollectGaugesAndEvents());
-
     return session;
   }
 
@@ -52,6 +53,11 @@ public static PerfSession createWithId(@NonNull String sessionId) {
   public PerfSession(String sessionId, Clock clock) {
     this.sessionId = sessionId;
     creationTime = clock.getTime();
+    // Every time a PerfSession is created, it sets the AQS to null. Once an AQS is received,
+    // SessionManagerKt verifies if this is an active session, and sets the AQS session ID.
+    // The assumption is that new PerfSessions *should* be limited to either App Start, or through
+    // AQS.
+    FirebasePerformanceSessionSubscriber.Companion.getInstance().reportPerfSession(sessionId);
   }
 
   private PerfSession(@NonNull Parcel in) {
@@ -63,7 +69,12 @@ private PerfSession(@NonNull Parcel in) {
 
   /** Returns the sessionId of the session. */
   public String sessionId() {
-    return sessionId;
+    return this.sessionId;
+  }
+
+  private String aqsSessionId() {
+    return FirebasePerformanceSessionSubscriber.Companion.getInstance()
+        .getAqsMappedToPerfSession(this.sessionId);
   }
 
   /** Returns the AQS sessionId for the given session. */
@@ -130,7 +141,7 @@ public boolean isSessionRunningTooLong() {
   public com.google.firebase.perf.v1.PerfSession build() {
     // TODO(b/394127311): Switch to using AQS.
     com.google.firebase.perf.v1.PerfSession.Builder sessionMetric =
-        com.google.firebase.perf.v1.PerfSession.newBuilder().setSessionId(sessionId);
+        com.google.firebase.perf.v1.PerfSession.newBuilder().setSessionId(aqsSessionId());
 
     // If gauge collection is enabled, enable gauge collection verbosity.
     if (isGaugeAndEventCollectionEnabled) {

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

@@ -19,6 +19,7 @@
 import androidx.annotation.Keep;
 import androidx.annotation.VisibleForTesting;
 import com.google.firebase.perf.application.AppStateMonitor;
+import com.google.firebase.perf.logging.AndroidLogger;
 import com.google.firebase.perf.session.gauges.GaugeManager;
 import com.google.firebase.perf.v1.ApplicationProcessState;
 import com.google.firebase.perf.v1.GaugeMetadata;
@@ -28,7 +29,7 @@
 import java.util.Iterator;
 import java.util.Objects;
 import java.util.Set;
-import java.util.UUID;
+import java.util.concurrent.Future;
 
 /** Session manager to generate sessionIDs and broadcast to the application. */
 @Keep // Needed because of b/117526359.
@@ -42,6 +43,7 @@ public class SessionManager {
   private final Set<WeakReference<SessionAwareObject>> clients = new HashSet<>();
 
   private PerfSession perfSession;
+  private Future syncInitFuture;
 
   /** Returns the singleton instance of SessionManager. */
   public static SessionManager getInstance() {
@@ -55,10 +57,7 @@ public final PerfSession perfSession() {
 
   private SessionManager() {
     // Generate a new sessionID for every cold start.
-    this(
-        GaugeManager.getInstance(),
-        PerfSession.createWithId(UUID.randomUUID().toString()),
-        AppStateMonitor.getInstance());
+    this(GaugeManager.getInstance(), PerfSession.createNewSession(), AppStateMonitor.getInstance());
   }
 
   @VisibleForTesting
@@ -74,7 +73,7 @@ public SessionManager(
    * (currently that is before onResume finishes) to ensure gauge collection starts on time.
    */
   public void setApplicationContext(final Context appContext) {
-    gaugeManager.initializeGaugeMetadataManager(appContext);
+    gaugeManager.initializeGaugeMetadataManager(appContext, ApplicationProcessState.FOREGROUND);
   }
 
   /**
@@ -102,6 +101,8 @@ public void updatePerfSession(PerfSession perfSession) {
       return;
     }
 
+    AndroidLogger.getInstance().debug("Perf Session Changed: " + perfSession);
+
     this.perfSession = perfSession;
 
     synchronized (clients) {
@@ -167,4 +168,9 @@ private void startOrStopCollectingGauges(ApplicationProcessState appState) {
   public void setPerfSession(PerfSession perfSession) {
     this.perfSession = perfSession;
   }
+
+  @VisibleForTesting
+  public Future getSyncInitFuture() {
+    return this.syncInitFuture;
+  }
 }

firebase-perf/src/main/java/com/google/firebase/perf/session/gauges/GaugeManager.java

@@ -22,6 +22,7 @@
 import com.google.firebase.components.Lazy;
 import com.google.firebase.perf.config.ConfigResolver;
 import com.google.firebase.perf.logging.AndroidLogger;
+import com.google.firebase.perf.session.FirebasePerformanceSessionSubscriber;
 import com.google.firebase.perf.session.PerfSession;
 import com.google.firebase.perf.transport.TransportManager;
 import com.google.firebase.perf.util.Timer;
@@ -59,7 +60,7 @@ public class GaugeManager {
   private final TransportManager transportManager;
 
   @Nullable private GaugeMetadataManager gaugeMetadataManager;
-  @Nullable private ScheduledFuture gaugeManagerDataCollectionJob = null;
+  @Nullable private ScheduledFuture<?> gaugeManagerDataCollectionJob = null;
   @Nullable private String sessionId = null;
   private ApplicationProcessState applicationProcessState =
       ApplicationProcessState.APPLICATION_PROCESS_STATE_UNKNOWN;
@@ -94,8 +95,10 @@ private GaugeManager() {
   }
 
   /** Initializes GaugeMetadataManager which requires application context. */
-  public void initializeGaugeMetadataManager(Context appContext) {
+  public void initializeGaugeMetadataManager(
+      Context appContext, ApplicationProcessState applicationProcessState) {
     this.gaugeMetadataManager = new GaugeMetadataManager(appContext);
+    this.applicationProcessState = applicationProcessState;
   }
 
   /** Returns the singleton instance of this class. */
@@ -136,7 +139,6 @@ public void startCollectingGauges(
     final String sessionIdForScheduledTask = sessionId;
     final ApplicationProcessState applicationProcessStateForScheduledTask = applicationProcessState;
 
-    // TODO(b/394127311): Switch to using AQS.
     try {
       gaugeManagerDataCollectionJob =
           gaugeManagerExecutor
@@ -205,10 +207,9 @@ public void stopCollectingGauges() {
       gaugeManagerDataCollectionJob.cancel(false);
     }
 
-    // TODO(b/394127311): Switch to using AQS.
     // Flush any data that was collected for this session one last time.
     @SuppressWarnings("FutureReturnValueIgnored")
-    ScheduledFuture unusedFuture =
+    ScheduledFuture<?> unusedFuture =
         gaugeManagerExecutor
             .get()
             .schedule(
@@ -244,31 +245,32 @@ private void syncFlush(String sessionId, ApplicationProcessState appState) {
     }
 
     // Adding Session ID info.
-    // TODO(b/394127311): Switch to using AQS.
-    gaugeMetricBuilder.setSessionId(sessionId);
+    String aqsSessionId =
+        FirebasePerformanceSessionSubscriber.Companion.getInstance()
+            .getAqsMappedToPerfSession(sessionId);
+    gaugeMetricBuilder.setSessionId(aqsSessionId);
+    AndroidLogger.getInstance().debug("CFPR syncFlush: " + sessionId + " AQS: " + aqsSessionId);
 
     transportManager.log(gaugeMetricBuilder.build(), appState);
   }
 
   /**
    * Log the Gauge Metadata information to the transport.
    *
-   * @param aqsSessionId The {@link PerfSession#aqsSessionId()} ()} to which the collected Gauge Metrics
+   * @param aqsSessionId The {@link FirebasePerformanceSessionSubscriber#getAqsMappedToPerfSession(String)} to which the collected Gauge Metrics
    *     should be associated with.
-   * @param appState The {@link ApplicationProcessState} for which these gauges are collected.
    * @return true if GaugeMetadata was logged, false otherwise.
    */
-  public boolean logGaugeMetadata(String aqsSessionId, ApplicationProcessState appState) {
-    if (gaugeMetadataManager != null) {
-      GaugeMetric gaugeMetric =
-          GaugeMetric.newBuilder()
-              .setSessionId(aqsSessionId)
-              .setGaugeMetadata(getGaugeMetadata())
-              .build();
-      transportManager.log(gaugeMetric, appState);
-      return true;
-    }
-    return false;
+  public void logGaugeMetadata(String aqsSessionId) {
+    // TODO(b/394127311): This can now throw an NPE. Explore if there's anything that should be
+    // verified.
+    AndroidLogger.getInstance().debug("CFPR logGaugeMetadata: " + aqsSessionId);
+    GaugeMetric gaugeMetric =
+        GaugeMetric.newBuilder()
+            .setSessionId(aqsSessionId)
+            .setGaugeMetadata(getGaugeMetadata())
+            .build();
+    transportManager.log(gaugeMetric, this.applicationProcessState);
   }
 
   private GaugeMetadata getGaugeMetadata() {