Add Sessions Internal API (#10665)

Author: samedson

FirebaseSessions.podspec

@@ -45,6 +45,7 @@ Pod::Spec.new do |s|
   s.dependency 'GoogleDataTransport', '~> 9.2'
   s.dependency 'GoogleUtilities/Environment', '~> 7.10'
   s.dependency 'nanopb', '>= 2.30908.0', '< 2.30910.0'
+  s.dependency 'PromisesSwift', '~> 2.1'
 
   s.pod_target_xcconfig = {
     'GCC_C_LANGUAGE_STANDARD' => 'c99',

FirebaseSessions/Sources/FirebaseSessions.swift

@@ -18,17 +18,13 @@ import Foundation
 @_implementationOnly import FirebaseCoreExtension
 @_implementationOnly import FirebaseInstallations
 @_implementationOnly import GoogleDataTransport
+@_implementationOnly import Promises
 
 private enum GoogleDataTransportConfig {
   static let sessionsLogSource = "1974"
   static let sessionsTarget = GDTCORTarget.FLL
 }
 
-@objc(FIRSessionsProvider)
-protocol SessionsProvider {
-  @objc static func sessions() -> Void
-}
-
 @objc(FIRSessions) final class Sessions: NSObject, Library, SessionsProvider {
   // MARK: - Private Variables
 
@@ -42,6 +38,19 @@ protocol SessionsProvider {
   private let appInfo: ApplicationInfo
   private let settings: SessionsSettings
 
+  /// Subscribers
+  /// `subscribers` are used to determine the Data Collection state of the Sessions SDK.
+  /// If any Subscribers has Data Collection enabled, the Sessions SDK will send events
+  private var subscribers: [SessionsSubscriber] = []
+  /// `subscriberPromises` are used to wait until all Subscribers have registered
+  /// themselves. Subscribers must have Data Collection state available upon registering.
+  private var subscriberPromises: [SessionsSubscriberName: Promise<Void>] = [:]
+
+  /// Notifications
+  static let SessionIDChangedNotificationName = Notification
+    .Name("SessionIDChangedNotificationName")
+  let notificationCenter = NotificationCenter()
+
   // MARK: - Initializers
 
   // Initializes the SDK and top-level classes
@@ -89,23 +98,104 @@ protocol SessionsProvider {
 
     super.init()
 
+    SessionsDependencies.dependencies.forEach { subscriberName in
+      self.subscriberPromises[subscriberName] = Promise<Void>.pending()
+    }
+
+    Logger.logDebug("Expecting subscriptions from: \(SessionsDependencies.dependencies)")
+
     self.initiator.beginListening {
-      // On each session start, first update Settings if expired
-      self.settings.updateSettings()
-      let session = self.sessionGenerator.generateNewSession()
-      // Generate a session start event only when session data collection is enabled and if the session is allowed to dispatch events
-      if self.settings.sessionsEnabled, session.shouldDispatchEvents {
-        let event = SessionStartEvent(sessionInfo: session, appInfo: self.appInfo)
-        DispatchQueue.global().async {
-          self.coordinator.attemptLoggingSessionStart(event: event) { result in
-          }
+      // Generating a Session ID early is important as Subscriber
+      // SDKs will need to read it immediately upon registration.
+      let sessionInfo = self.sessionGenerator.generateNewSession()
+
+      // Post a notification so subscriber SDKs can get an updated Session ID
+      self.notificationCenter.post(name: Sessions.SessionIDChangedNotificationName,
+                                   object: nil)
+
+      let event = SessionStartEvent(sessionInfo: sessionInfo, appInfo: self.appInfo)
+
+      // Wait until all subscriber promises have been fulfilled before
+      // doing any data collection.
+      all(self.subscriberPromises.values).then(on: .global(qos: .background)) { _ in
+        guard self.isAnyDataCollectionEnabled else {
+          Logger
+            .logDebug(
+              "Data Collection is disabled for all subscribers. Skipping this Session Event"
+            )
+          return
+        }
+
+        Logger.logDebug("Data Collection is enabled for at least one Subscriber")
+
+        // Fetch settings if they have expired. This must happen after the check for
+        // data collection because it uses the network, but it must happen before the
+        // check for sessionsEnabled from Settings because otherwise we would permanently
+        // turn off the Sessions SDK when we disabled it.
+        self.settings.updateSettings()
+
+        self.addEventDataCollectionState(event: event)
+
+        if !(self.settings.sessionsEnabled && sessionInfo.shouldDispatchEvents) {
+          Logger
+            .logDebug(
+              "Session Event logging is disabled sessionsEnabled: \(self.settings.sessionsEnabled), shouldDispatchEvents: \(sessionInfo.shouldDispatchEvents)"
+            )
+          return
+        }
+
+        self.coordinator.attemptLoggingSessionStart(event: event) { result in
         }
-      } else {
-        Logger.logDebug("Session logging is disabled by configuration settings.")
       }
     }
   }
 
+  // MARK: - Data Collection
+
+  var isAnyDataCollectionEnabled: Bool {
+    for subscriber in subscribers {
+      if subscriber.isDataCollectionEnabled {
+        return true
+      }
+    }
+    return false
+  }
+
+  func addEventDataCollectionState(event: SessionStartEvent) {
+    subscribers.forEach { subscriber in
+      event.set(subscriber: subscriber.sessionsSubscriberName,
+                isDataCollectionEnabled: subscriber.isDataCollectionEnabled)
+    }
+  }
+
+  // MARK: - SessionsProvider
+
+  var currentSessionDetails: SessionDetails {
+    return SessionDetails(sessionId: sessionGenerator.currentSession?.sessionId)
+  }
+
+  func register(subscriber: SessionsSubscriber) {
+    Logger
+      .logDebug(
+        "Registering Sessions SDK subscriber with name: \(subscriber.sessionsSubscriberName), data collection enabled: \(subscriber.isDataCollectionEnabled)"
+      )
+
+    notificationCenter.addObserver(
+      forName: Sessions.SessionIDChangedNotificationName,
+      object: nil,
+      queue: nil
+    ) { notification in
+      subscriber.onSessionChanged(self.currentSessionDetails)
+    }
+    // Immediately call the callback because the Sessions SDK starts
+    // before subscribers, so subscribers will miss the first Notification
+    subscriber.onSessionChanged(currentSessionDetails)
+
+    // Fulfil this subscriber's promise
+    subscribers.append(subscriber)
+    subscriberPromises[subscriber.sessionsSubscriberName]?.fulfill(())
+  }
+
   // MARK: - Library conformance
 
   static func componentsToRegister() -> [Component] {
@@ -119,8 +209,4 @@ protocol SessionsProvider {
         return self.init(appID: app.options.googleAppID, installations: installations)
       }]
   }
-
-  // MARK: - SessionsProvider conformance
-
-  static func sessions() {}
 }

FirebaseSessions/Sources/Public/SessionsDependencies.swift

@@ -0,0 +1,32 @@
+//
+// Copyright 2022 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.
+
+import Foundation
+
+// Sessions Dependencies determines when a dependent SDK is
+// installed in the app. The Sessions SDK uses this to figure
+// out which dependencies to wait for to getting the data
+// collection state.
+//
+// This is important because the Sessions SDK starts up before
+// dependent SDKs
+@objc(FIRSessionsDependencies)
+public class SessionsDependencies: NSObject {
+  static var dependencies: Set<SessionsSubscriberName> = .init()
+
+  @objc public static func addDependency(name: SessionsSubscriberName) {
+    SessionsDependencies.dependencies.insert(name)
+  }
+}

FirebaseSessions/Sources/Public/SessionsProvider.swift

@@ -0,0 +1,23 @@
+//
+// Copyright 2022 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.
+
+import Foundation
+
+// Sessions Provider is the Session SDK's internal
+// interface for other 1P SDKs to talk to.
+@objc(FIRSessionsProvider)
+public protocol SessionsProvider {
+  @objc func register(subscriber: SessionsSubscriber)
+}

FirebaseSessions/Sources/Public/SessionsSubscriber.swift

@@ -0,0 +1,56 @@
+//
+// Copyright 2022 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.
+
+import Foundation
+
+/// Sessions Subscriber is an interface that dependent SDKs
+/// must implement.
+@objc(FIRSessionsSubscriber)
+public protocol SessionsSubscriber {
+  func onSessionChanged(_ session: SessionDetails)
+  var isDataCollectionEnabled: Bool { get }
+  var sessionsSubscriberName: SessionsSubscriberName { get }
+}
+
+/// Session Payload is a container for Session Data passed to Subscribers
+/// whenever the Session changes
+@objc(FIRSessionDetails)
+public class SessionDetails: NSObject {
+  var sessionId: String?
+
+  public init(sessionId: String?) {
+    self.sessionId = sessionId
+    super.init()
+  }
+}
+
+/// Session Subscriber Names are used for identifying subscribers
+@objc(FIRSessionsSubscriberName)
+public enum SessionsSubscriberName: Int, CustomStringConvertible {
+  case Unknown
+  case Crashlytics
+  case Performance
+
+  public var description: String {
+    switch self {
+    case .Crashlytics:
+      return "Crashlytics"
+    case .Performance:
+      return "Performance"
+    default:
+      return "Unknown"
+    }
+  }
+}

FirebaseSessions/Sources/SessionGenerator.swift

@@ -62,7 +62,7 @@ class SessionGenerator {
     return newSession
   }
 
-  func currentSession() -> SessionInfo? {
+  var currentSession: SessionInfo? {
     return thisSession
   }
 }

FirebaseSessions/Sources/SessionStartEvent.swift

@@ -65,9 +65,9 @@ class SessionStartEvent: NSObject, GDTCOREventDataObject {
     proto.application_info.apple_app_info.mcc_mnc = makeProtoString(appInfo.mccMNC)
 
     proto.session_data.data_collection_status
-      .crashlytics = firebase_appquality_sessions_DataCollectionState_COLLECTION_UNKNOWN
+      .crashlytics = firebase_appquality_sessions_DataCollectionState_COLLECTION_SDK_NOT_INSTALLED
     proto.session_data.data_collection_status
-      .performance = firebase_appquality_sessions_DataCollectionState_COLLECTION_UNKNOWN
+      .performance = firebase_appquality_sessions_DataCollectionState_COLLECTION_SDK_NOT_INSTALLED
   }
 
   func setInstallationID(installationId: String) {
@@ -78,6 +78,19 @@ class SessionStartEvent: NSObject, GDTCOREventDataObject {
     proto.session_data.data_collection_status.session_sampling_rate = samplingRate
   }
 
+  func set(subscriber: SessionsSubscriberName, isDataCollectionEnabled: Bool) {
+    let dataCollectionState = makeDataCollectionProto(isDataCollectionEnabled)
+    switch subscriber {
+    case .Crashlytics:
+      proto.session_data.data_collection_status.crashlytics = dataCollectionState
+    case .Performance:
+      proto.session_data.data_collection_status.performance = dataCollectionState
+    default:
+      Logger
+        .logWarning("Attempted to set Data Collection status for unknown Subscriber: \(subscriber)")
+    }
+  }
+
   // MARK: - GDTCOREventDataObject
 
   func transportBytes() -> Data {
@@ -96,6 +109,15 @@ class SessionStartEvent: NSObject, GDTCOREventDataObject {
 
   // MARK: - Data Conversion
 
+  func makeDataCollectionProto(_ isDataCollectionEnabled: Bool)
+    -> firebase_appquality_sessions_DataCollectionState {
+    if isDataCollectionEnabled {
+      return firebase_appquality_sessions_DataCollectionState_COLLECTION_ENABLED
+    } else {
+      return firebase_appquality_sessions_DataCollectionState_COLLECTION_DISABLED
+    }
+  }
+
   private func makeProtoStringOrNil(_ string: String?) -> UnsafeMutablePointer<pb_bytes_array_t>? {
     guard let string = string else {
       return nil

FirebaseSessions/Tests/Unit/SessionGeneratorTests.swift

@@ -76,7 +76,7 @@ class SessionGeneratorTests: XCTestCase {
   // with the Sessions SDK, we may want to move to a lazy solution where
   // sessionID can never be empty
   func test_sessionID_beforeGenerateReturnsNothing() throws {
-    XCTAssertNil(generator.currentSession())
+    XCTAssertNil(generator.currentSession)
   }
 
   func test_generateNewSessionID_generatesValidID() throws {

FirebaseSessions/Tests/Unit/SessionStartEventTests.swift

@@ -208,11 +208,11 @@ class SessionStartEventTests: XCTestCase {
     testProtoAndDecodedProto(sessionEvent: event) { proto in
       XCTAssertEqual(
         proto.session_data.data_collection_status.performance,
-        firebase_appquality_sessions_DataCollectionState_COLLECTION_UNKNOWN
+        firebase_appquality_sessions_DataCollectionState_COLLECTION_SDK_NOT_INSTALLED
       )
       XCTAssertEqual(
         proto.session_data.data_collection_status.crashlytics,
-        firebase_appquality_sessions_DataCollectionState_COLLECTION_UNKNOWN
+        firebase_appquality_sessions_DataCollectionState_COLLECTION_SDK_NOT_INSTALLED
       )
     }
   }

Package.swift

@@ -1089,6 +1089,7 @@ let package = Package(
         "FirebaseInstallations",
         "FirebaseCoreExtension",
         "FirebaseSessionsObjC",
+        .product(name: "Promises", package: "Promises"),
         .product(name: "GoogleDataTransport", package: "GoogleDataTransport"),
         .product(name: "GULEnvironment", package: "GoogleUtilities"),
       ],