Add double background pixel with timestamps of possible interfering e…

…vents (#3749)

Task/Issue URL: https://app.asana.com/0/0/1208997399449398/f

**Description**:
Add double background pixel with timestamps of possibly interfering
events

Core/Pixel.swift

@@ -165,6 +165,16 @@ public struct PixelParameters {
 
     public static let appState = "state"
     public static let appEvent = "event"
+
+    public static let firstBackgroundTimestamp = "firstBackgroundTimestamp"
+    public static let secondBackgroundTimestamp = "secondBackgroundTimestamp"
+    public static let didReceiveMemoryWarningTimestamp = "didReceiveMemoryWarningTimestamp"
+    public static let didReceiveMXPayloadTimestamp = "didReceiveMXPayloadTimestamp"
+    public static let didReceiveUNNotification = "didReceiveUNNotification"
+    public static let didStartRemoteMessagingClientBackgroundTask = "didStartRemoteMessagingClientBackgroundTask"
+    public static let didStartAppConfigurationFetchBackgroundTask = "didStartAppConfigurationFetchBackgroundTask"
+    public static let didPerformFetchTimestamp = "didPerformFetchTimestamp"
+    public static let numberOfBackgrounds = "numberOfBackgrounds"
 }
 
 public struct PixelValues {

Core/PixelEvent.swift

@@ -947,6 +947,7 @@ extension Pixel {
 
         // MARK: Lifecycle
         case appDidTransitionToUnexpectedState
+        case appDidConsecutivelyBackground
     }
 
 }
@@ -1891,6 +1892,7 @@ extension Pixel.Event {
 
         // MARK: Lifecycle
         case .appDidTransitionToUnexpectedState: return "m_debug_app-did-transition-to-unexpected-state"
+        case .appDidConsecutivelyBackground: return "m_debug_app-did-consecutively-background"
 
         }
     }

DuckDuckGo/AppConfigurationFetch.swift

@@ -85,6 +85,8 @@ class AppConfigurationFetch {
         return Date().timeIntervalSince(Self.lastConfigurationRefreshDate) > Constants.minimumConfigurationRefreshInterval
     }
 
+    static var didStartBackgroundTaskTimestamp: Date?
+
     enum BackgroundRefreshCompletionStatus {
 
         case expired
@@ -132,6 +134,7 @@ class AppConfigurationFetch {
 
     static func registerBackgroundRefreshTaskHandler() {
         BGTaskScheduler.shared.register(forTaskWithIdentifier: Constants.backgroundProcessingTaskIdentifier, using: nil) { (task) in
+            didStartBackgroundTaskTimestamp = Date()
             guard shouldRefresh else {
                 task.setTaskCompleted(success: true)
                 scheduleBackgroundRefreshTask()

DuckDuckGo/AppDelegate.swift

@@ -181,7 +181,8 @@ import os.log
             Configuration.setURLProvider(AppConfigurationURLProvider())
         }
 
-        crashCollection.startAttachingCrashLogMessages { pixelParameters, payloads, sendReport in
+        crashCollection.startAttachingCrashLogMessages { [weak self] pixelParameters, payloads, sendReport in
+            self?.didReceiveMXPayloadTimestamp = Date()
             pixelParameters.forEach { params in
                 Pixel.fire(pixel: .dbCrashDetected, withAdditionalParameters: params, includedParameters: [])
 
@@ -198,11 +199,11 @@ import os.log
 
             // Async dispatch because rootViewController may otherwise be nil here
             DispatchQueue.main.async {
-                guard let viewController = self.window?.rootViewController else { return }
+                guard let viewController = self?.window?.rootViewController else { return }
 
                 let crashReportUploaderOnboarding = CrashCollectionOnboarding(appSettings: AppDependencyProvider.shared.appSettings)
                 crashReportUploaderOnboarding.presentOnboardingIfNeeded(for: payloads, from: viewController, sendReport: sendReport)
-                self.crashReportUploaderOnboarding = crashReportUploaderOnboarding
+                self?.crashReportUploaderOnboarding = crashReportUploaderOnboarding
             }
         }
 
@@ -919,7 +920,7 @@ import os.log
     func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
 
         Logger.lifecycle.debug(#function)
-
+        didPerformFetchTimestamp = Date()
         AppConfigurationFetch().start(isBackgroundFetch: true) { result in
             switch result {
             case .noData:
@@ -1166,6 +1167,21 @@ import os.log
             UIApplication.shared.shortcutItems = nil
         }
     }
+
+    var didReceiveMemoryWarningTimestamp: Date?
+    func applicationDidReceiveMemoryWarning(_ application: UIApplication) {
+        didReceiveMemoryWarningTimestamp = Date()
+    }
+    var didReceiveMXPayloadTimestamp: Date?
+    var didReceiveUNNotificationTimestamp: Date?
+    var didStartRemoteMessagingClientBackgroundTaskTimestamp: Date? {
+        remoteMessagingClient.didStartBackgroundTaskTimestamp
+    }
+    var didStartAppConfigurationFetchBackgroundTaskTimestamp: Date? {
+        AppConfigurationFetch.didStartBackgroundTaskTimestamp
+    }
+
+    var didPerformFetchTimestamp: Date?
 }
 
 extension AppDelegate: BlankSnapshotViewRecoveringDelegate {
@@ -1218,6 +1234,7 @@ extension AppDelegate: UNUserNotificationCenterDelegate {
     func userNotificationCenter(_ center: UNUserNotificationCenter,
                                 didReceive response: UNNotificationResponse,
                                 withCompletionHandler completionHandler: @escaping () -> Void) {
+        didReceiveUNNotificationTimestamp = Date()
         if response.actionIdentifier == UNNotificationDefaultActionIdentifier {
             let identifier = response.notification.request.identifier
 

DuckDuckGo/AppLifecycle/AppStateTransitions.swift

@@ -91,7 +91,7 @@ extension Background {
         case .openURL:
             return self
         case .backgrounding:
-            return DoubleBackground()
+            return DoubleBackground(previousDidEnterBackgroundTimestamp: timestamp, counter: 0)
         case .launching, .suspending:
             return handleUnexpectedEvent(event)
         }
@@ -102,15 +102,14 @@ extension Background {
 extension DoubleBackground {
 
     func apply(event: AppEvent) -> any AppState {
-        // report event so we know what events can be called at this moment, but do not let SM be stuck in this state just not to be flooded with these events
-        _ = handleUnexpectedEvent(event)
-
         switch event {
         case .activating(let application):
             return Active(application: application)
         case .suspending(let application):
             return Inactive(application: application)
-        case .launching, .backgrounding, .openURL:
+        case .backgrounding(let application):
+            return DoubleBackground(previousDidEnterBackgroundTimestamp: currentDidEnterBackgroundTimestamp, counter: counter)
+        case .launching, .openURL:
             return self
         }
 
@@ -121,9 +120,6 @@ extension DoubleBackground {
 extension InactiveBackground {
 
     func apply(event: AppEvent) -> any AppState {
-        // report event so we know what events can be called at this moment, but do not let SM be stuck in this state just not to be flooded with these events
-        _ = handleUnexpectedEvent(event)
-
         switch event {
         case .activating(let application):
             return Active(application: application)

DuckDuckGo/AppLifecycle/AppStates/Background.swift

@@ -18,15 +18,73 @@
 //
 
 import UIKit
+import Core
 
 struct Background: AppState {
 
+    let timestamp = Date()
+
     init(application: UIApplication) {
 
     }
 
 }
 
 struct DoubleBackground: AppState {
-
+
+    private let dateFormatter: ISO8601DateFormatter = {
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime]
+        return formatter
+    }()
+
+    let currentDidEnterBackgroundTimestamp: Date
+    var counter: Int
+
+    init(previousDidEnterBackgroundTimestamp: Date, counter: Int) {
+        self.currentDidEnterBackgroundTimestamp = Date()
+        self.counter = counter + 1
+
+        var parameters = [
+            PixelParameters.firstBackgroundTimestamp: dateFormatter.string(from: previousDidEnterBackgroundTimestamp),
+            PixelParameters.secondBackgroundTimestamp: dateFormatter.string(from: currentDidEnterBackgroundTimestamp)
+        ]
+
+        if counter < 5 {
+            parameters[PixelParameters.numberOfBackgrounds] = String(counter)
+        }
+
+        func isValid(timestamp: Date) -> Bool {
+            timestamp >= previousDidEnterBackgroundTimestamp && timestamp <= currentDidEnterBackgroundTimestamp
+        }
+
+        if let appDelegate = UIApplication.shared.delegate as? AppDelegate {
+            if let didReceiveMemoryWarningTimestamp = appDelegate.didReceiveMemoryWarningTimestamp,
+               isValid(timestamp: didReceiveMemoryWarningTimestamp) {
+                parameters[PixelParameters.didReceiveMemoryWarningTimestamp] = dateFormatter.string(from: didReceiveMemoryWarningTimestamp)
+            }
+            if let didReceiveMXPayloadTimestamp = appDelegate.didReceiveMXPayloadTimestamp,
+               isValid(timestamp: didReceiveMXPayloadTimestamp) {
+                parameters[PixelParameters.didReceiveMXPayloadTimestamp] = dateFormatter.string(from: didReceiveMXPayloadTimestamp)
+            }
+            if let didReceiveUNNotificationTimestamp = appDelegate.didReceiveUNNotificationTimestamp,
+               isValid(timestamp: didReceiveUNNotificationTimestamp) {
+                parameters[PixelParameters.didReceiveUNNotification] = dateFormatter.string(from: didReceiveUNNotificationTimestamp)
+            }
+            if let didStartRemoteMessagingClientBackgroundTaskTimestamp = appDelegate.didStartRemoteMessagingClientBackgroundTaskTimestamp,
+               isValid(timestamp: didStartRemoteMessagingClientBackgroundTaskTimestamp) {
+                parameters[PixelParameters.didStartRemoteMessagingClientBackgroundTask] = dateFormatter.string(from: didStartRemoteMessagingClientBackgroundTaskTimestamp)
+            }
+            if let didStartAppConfigurationFetchBackgroundTaskTimestamp = appDelegate.didStartAppConfigurationFetchBackgroundTaskTimestamp,
+               isValid(timestamp: didStartAppConfigurationFetchBackgroundTaskTimestamp) {
+                parameters[PixelParameters.didStartAppConfigurationFetchBackgroundTask] = dateFormatter.string(from: didStartAppConfigurationFetchBackgroundTaskTimestamp)
+            }
+            if let didPerformFetchTimestamp = appDelegate.didPerformFetchTimestamp,
+               isValid(timestamp: didPerformFetchTimestamp) {
+                parameters[PixelParameters.didPerformFetchTimestamp] = dateFormatter.string(from: didPerformFetchTimestamp)
+            }
+        }
+        Pixel.fire(pixel: .appDidConsecutivelyBackground, withAdditionalParameters: parameters)
+    }
+
 }

DuckDuckGo/RemoteMessagingClient.swift

@@ -48,6 +48,8 @@ final class RemoteMessagingClient: RemoteMessagingProcessing {
     let store: RemoteMessagingStoring
     let remoteMessagingAvailabilityProvider: RemoteMessagingAvailabilityProviding
 
+    var didStartBackgroundTaskTimestamp: Date?
+
     convenience init(
         bookmarksDatabase: CoreDataDatabase,
         appSettings: AppSettings,
@@ -113,7 +115,8 @@ extension RemoteMessagingClient {
         let remoteMessagingAvailabilityProvider = remoteMessagingAvailabilityProvider
         let store = store
 
-        BGTaskScheduler.shared.register(forTaskWithIdentifier: Constants.backgroundRefreshTaskIdentifier, using: nil) { task in
+        BGTaskScheduler.shared.register(forTaskWithIdentifier: Constants.backgroundRefreshTaskIdentifier, using: nil) { [weak self] task in
+            self?.didStartBackgroundTaskTimestamp = Date()
             guard Self.shouldRefresh else {
                 task.setTaskCompleted(success: true)
                 Self.scheduleBackgroundRefreshTask()