Update GaugeManager and SessionManager to separate app state changes and PerfSession changes

firebase-perf/firebase-perf.gradle

@@ -70,13 +70,15 @@ android {
         buildConfigField("String", "TRANSPORT_LOG_SRC", "String.valueOf(\"FIREPERF\")")
         buildConfigField("Boolean", "ENFORCE_DEFAULT_LOG_SRC", "Boolean.valueOf(false)")
         buildConfigField("String", "FIREPERF_VERSION_NAME", "String.valueOf(\"" + property("version") + "\")")
+        buildConfigField("Boolean", "ENFORCE_LEGACY_SESSIONS", "Boolean.valueOf(false)")
 
         if (project.hasProperty("fireperfBuildForAutopush")) {
             // This allows the SDK to be built for "Autopush" env when the mentioned flag
             // (-PfireperfBuildForAutopush) is passed in the gradle build command (of either the
             // SDK or the Test App).
             buildConfigField("String", "TRANSPORT_LOG_SRC", "String.valueOf(\"FIREPERF_AUTOPUSH\")")
             buildConfigField("Boolean", "ENFORCE_DEFAULT_LOG_SRC", "Boolean.valueOf(true)")
+            buildConfigField("Boolean", "ENFORCE_LEGACY_SESSIONS", "Boolean.valueOf(true)")
         }
 
         minSdkVersion project.minSdkVersion
@@ -118,7 +120,7 @@ dependencies {
     api("com.google.firebase:firebase-components:18.0.0")
     api("com.google.firebase:firebase-config:21.5.0")
     api("com.google.firebase:firebase-installations:17.2.0")
-    api("com.google.firebase:firebase-sessions:2.0.7") {
+    api(project(":firebase-sessions")) {
         exclude group: 'com.google.firebase', module: 'firebase-common'
         exclude group: 'com.google.firebase', module: 'firebase-common-ktx'
         exclude group: 'com.google.firebase', module: 'firebase-components'

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

@@ -51,12 +51,8 @@ public FirebasePerfEarly(
       uiExecutor.execute(new AppStartTrace.StartFromBackgroundRunnable(appStartTrace));
     }
 
-    // TODO: Bring back Firebase Sessions dependency to watch for updates to sessions.
+    // In the case of a cold start, we initialize gauge collection with a legacy PerfSession.
 
-    // 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.
     SessionManager.getInstance().initializeGaugeCollection();
   }
 }

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

@@ -30,6 +30,8 @@
 import com.google.firebase.perf.injection.modules.FirebasePerformanceModule;
 import com.google.firebase.platforminfo.LibraryVersionComponent;
 import com.google.firebase.remoteconfig.RemoteConfigComponent;
+import com.google.firebase.sessions.api.FirebaseSessionsDependencies;
+import com.google.firebase.sessions.api.SessionSubscriber;
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.Executor;
@@ -47,6 +49,11 @@ public class FirebasePerfRegistrar implements ComponentRegistrar {
   private static final String LIBRARY_NAME = "fire-perf";
   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);
+  }
+
   @Override
   @Keep
   public List<Component<?>> getComponents() {

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

@@ -34,14 +34,18 @@
 import com.google.firebase.perf.config.RemoteConfigManager;
 import com.google.firebase.perf.logging.AndroidLogger;
 import com.google.firebase.perf.logging.ConsoleUrlGenerator;
+import com.google.firebase.perf.logging.FirebaseSessionsEnforcementCheck;
 import com.google.firebase.perf.metrics.HttpMetric;
 import com.google.firebase.perf.metrics.Trace;
+import com.google.firebase.perf.session.FirebasePerformanceSessionSubscriber;
 import com.google.firebase.perf.session.SessionManager;
 import com.google.firebase.perf.transport.TransportManager;
 import com.google.firebase.perf.util.Constants;
 import com.google.firebase.perf.util.ImmutableBundle;
 import com.google.firebase.perf.util.Timer;
 import com.google.firebase.remoteconfig.RemoteConfigComponent;
+import com.google.firebase.sessions.api.FirebaseSessionsDependencies;
+import com.google.firebase.sessions.api.SessionSubscriber;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.net.URL;
@@ -92,6 +96,8 @@ public class FirebasePerformance implements FirebasePerformanceAttributable {
   // once during initialization and cache it.
   private final ImmutableBundle mMetadataBundle;
 
+  private final SessionSubscriber sessionSubscriber;
+
   /** Valid HttpMethods for manual network APIs */
   @StringDef({
     HttpMethod.GET,
@@ -136,11 +142,6 @@ public static FirebasePerformance getInstance() {
   // to false if it's been force disabled or it is set to null if neither.
   @Nullable private Boolean mPerformanceCollectionForceEnabledState = null;
 
-  private final FirebaseApp firebaseApp;
-  private final Provider<RemoteConfigComponent> firebaseRemoteConfigProvider;
-  private final FirebaseInstallationsApi firebaseInstallationsApi;
-  private final Provider<TransportFactory> transportFactoryProvider;
-
   /**
    * Constructs the FirebasePerformance class and allows injecting dependencies.
    *
@@ -166,23 +167,19 @@ public static FirebasePerformance getInstance() {
       ConfigResolver configResolver,
       SessionManager sessionManager) {
 
-    this.firebaseApp = firebaseApp;
-    this.firebaseRemoteConfigProvider = firebaseRemoteConfigProvider;
-    this.firebaseInstallationsApi = firebaseInstallationsApi;
-    this.transportFactoryProvider = transportFactoryProvider;
-
     if (firebaseApp == null) {
       this.mPerformanceCollectionForceEnabledState = false;
       this.configResolver = configResolver;
       this.mMetadataBundle = new ImmutableBundle(new Bundle());
+      this.sessionSubscriber = new FirebasePerformanceSessionSubscriber(false);
       return;
     }
+    FirebaseSessionsEnforcementCheck.setEnforcement(BuildConfig.ENFORCE_LEGACY_SESSIONS);
 
     TransportManager.getInstance()
         .initialize(firebaseApp, firebaseInstallationsApi, transportFactoryProvider);
 
     Context appContext = firebaseApp.getApplicationContext();
-    // TODO(b/110178816): Explore moving off of main thread.
     mMetadataBundle = extractMetadata(appContext);
 
     remoteConfigManager.setFirebaseRemoteConfigProvider(firebaseRemoteConfigProvider);
@@ -192,6 +189,9 @@ public static FirebasePerformance getInstance() {
     sessionManager.setApplicationContext(appContext);
 
     mPerformanceCollectionForceEnabledState = configResolver.getIsPerformanceCollectionEnabled();
+    sessionSubscriber = new FirebasePerformanceSessionSubscriber(isPerformanceCollectionEnabled());
+    FirebaseSessionsDependencies.register(sessionSubscriber);
+
     if (logger.isLogcatEnabled() && isPerformanceCollectionEnabled()) {
       logger.info(
           String.format(
@@ -282,7 +282,7 @@ public synchronized void setPerformanceCollectionEnabled(@Nullable Boolean enabl
       return;
     }
 
-    if (configResolver.getIsPerformanceCollectionDeactivated()) {
+    if (Boolean.TRUE.equals(configResolver.getIsPerformanceCollectionDeactivated())) {
       logger.info("Firebase Performance is permanently disabled");
       return;
     }
@@ -466,4 +466,9 @@ private static ImmutableBundle extractMetadata(Context appContext) {
   Boolean getPerformanceCollectionForceEnabledState() {
     return mPerformanceCollectionForceEnabledState;
   }
+
+  @VisibleForTesting
+  SessionSubscriber getSessionSubscriber() {
+    return sessionSubscriber;
+  }
 }

firebase-perf/src/main/java/com/google/firebase/perf/logging/FirebaseSessionsEnforcementCheck.kt

@@ -0,0 +1,36 @@
+/*
+ * 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.logging
+
+import com.google.firebase.perf.session.PerfSession
+import com.google.firebase.perf.session.isLegacy
+
+class FirebaseSessionsEnforcementCheck {
+  companion object {
+    /** When enabled, failed preconditions will cause assertion errors for debugging. */
+    @JvmStatic var enforcement: Boolean = false
+    private var logger: AndroidLogger = AndroidLogger.getInstance()
+
+    @JvmStatic
+    fun checkSession(session: PerfSession, failureMessage: String) {
+      if (session.isLegacy()) {
+        logger.debug("legacy session ${session.sessionId()}: $failureMessage")
+        assert(!enforcement) { failureMessage }
+      }
+    }
+  }
+}

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

@@ -0,0 +1,46 @@
+/*
+ * 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.logging.FirebaseSessionsEnforcementCheck
+import com.google.firebase.perf.session.gauges.GaugeManager
+import com.google.firebase.perf.v1.ApplicationProcessState
+import com.google.firebase.sessions.api.SessionSubscriber
+
+class FirebasePerformanceSessionSubscriber(override val isDataCollectionEnabled: Boolean) :
+  SessionSubscriber {
+
+  override val sessionSubscriberName: SessionSubscriber.Name = SessionSubscriber.Name.PERFORMANCE
+
+  override fun onSessionChanged(sessionDetails: SessionSubscriber.SessionDetails) {
+    val currentPerfSession = SessionManager.getInstance().perfSession()
+    FirebaseSessionsEnforcementCheck.checkSession(currentPerfSession, "onSessionChanged")
+
+    if (currentPerfSession.isLegacy() && currentPerfSession.isVerbose) {
+      GaugeManager.getInstance()
+        .logGaugeMetadata(sessionDetails.sessionId, ApplicationProcessState.FOREGROUND)
+      GaugeManager.getInstance()
+        .logExistingGaugeMetrics(sessionDetails.sessionId, ApplicationProcessState.FOREGROUND)
+    }
+
+    val updatedSession = PerfSession.createWithId(sessionDetails.sessionId)
+    SessionManager.getInstance().updatePerfSession(updatedSession)
+    GaugeManager.getInstance()
+      .logGaugeMetadata(updatedSession.sessionId(), ApplicationProcessState.FOREGROUND)
+    SessionManager.getInstance().updateGaugeCollectionOnNewSession()
+  }
+}

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

@@ -0,0 +1,40 @@
+/*
+ * 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.util.Constants
+import java.util.UUID
+
+/** Identifies whether the [PerfSession] is legacy or not. */
+fun PerfSession.isLegacy(): Boolean {
+  return this.sessionId().isLegacy()
+}
+
+/** Identifies whether the string is from a legacy [PerfSession]. */
+fun String.isLegacy(): Boolean {
+  return this.startsWith(Constants.UNDEFINED_AQS_ID_PREFIX)
+}
+
+/** Creates a valid session ID for [PerfSession] that can be predictably identified as legacy. */
+fun createLegacySessionId(): String {
+  val uuid = UUID.randomUUID().toString().replace("-", "")
+  return uuid.replaceRange(
+    0,
+    Constants.UNDEFINED_AQS_ID_PREFIX.length,
+    Constants.UNDEFINED_AQS_ID_PREFIX
+  )
+}

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

@@ -28,20 +28,20 @@
 
 /** Details of a session including a unique Id and related information. */
 public class PerfSession implements Parcelable {
-
-  private final String sessionId;
   private final Timer creationTime;
-
-  private boolean isGaugeAndEventCollectionEnabled = false;
+  private final String sessionId;
+  private boolean isGaugeAndEventCollectionEnabled = true;
 
   /*
    * Creates a PerfSession object and decides what metrics to collect.
    */
-  public static PerfSession createWithId(@NonNull String sessionId) {
-    String prunedSessionId = sessionId.replace("-", "");
-    PerfSession session = new PerfSession(prunedSessionId, new Clock());
-    session.setGaugeAndEventCollectionEnabled(shouldCollectGaugesAndEvents());
-
+  public static PerfSession createWithId(@Nullable String aqsSessionId) {
+    String sessionId = aqsSessionId;
+    if (sessionId == null) {
+      sessionId = FirebaseSessionsHelperKt.createLegacySessionId();
+    }
+    PerfSession session = new PerfSession(sessionId, new Clock());
+    session.setGaugeAndEventCollectionEnabled(session.shouldCollectGaugesAndEvents());
     return session;
   }
 
@@ -59,7 +59,8 @@ private PerfSession(@NonNull Parcel in) {
     creationTime = in.readParcelable(Timer.class.getClassLoader());
   }
 
-  /** Returns the sessionId of the object. */
+  /** Returns the sessionId for the given session. */
+  @NonNull
   public String sessionId() {
     return sessionId;
   }
@@ -90,18 +91,6 @@ public boolean isVerbose() {
     return isGaugeAndEventCollectionEnabled;
   }
 
-  /** Checks if the current {@link com.google.firebase.perf.v1.PerfSession} is verbose or not. */
-  @VisibleForTesting
-  static boolean isVerbose(@NonNull com.google.firebase.perf.v1.PerfSession perfSession) {
-    for (SessionVerbosity sessionVerbosity : perfSession.getSessionVerbosityList()) {
-      if (sessionVerbosity == SessionVerbosity.GAUGES_AND_SYSTEM_EVENTS) {
-        return true;
-      }
-    }
-
-    return false;
-  }
-
   /**
    * Checks if it has been more than {@link ConfigResolver#getSessionsMaxDurationMinutes()} time
    * since the creation time of the current session.
@@ -163,11 +152,11 @@ public static com.google.firebase.perf.v1.PerfSession[] buildAndSort(
   }
 
   /** If true, Session Gauge collection is enabled. */
-  public static boolean shouldCollectGaugesAndEvents() {
+  public boolean shouldCollectGaugesAndEvents() {
     ConfigResolver configResolver = ConfigResolver.getInstance();
-
     return configResolver.isPerformanceMonitoringEnabled()
-        && Math.random() < configResolver.getSessionsSamplingRate();
+        && (Math.abs(this.sessionId.hashCode() % 100)
+            < configResolver.getSessionsSamplingRate() * 100);
   }
 
   /**
@@ -208,4 +197,16 @@ public PerfSession[] newArray(int size) {
           return new PerfSession[size];
         }
       };
+
+  /** Checks if the current {@link com.google.firebase.perf.v1.PerfSession} is verbose or not. */
+  @VisibleForTesting
+  static boolean isVerbose(@NonNull com.google.firebase.perf.v1.PerfSession perfSession) {
+    for (SessionVerbosity sessionVerbosity : perfSession.getSessionVerbosityList()) {
+      if (sessionVerbosity == SessionVerbosity.GAUGES_AND_SYSTEM_EVENTS) {
+        return true;
+      }
+    }
+
+    return false;
+  }
 }