RUMM-1064 AppStateListener.shared is added

DataDog · Mar 12, 2021 · ee69ce5 · ee69ce5
1 parent e80713d
commit ee69ce5
Show file tree

Hide file tree

Showing 3 changed files with 49 additions and 43 deletions.
diff --git a/Sources/Datadog/Core/System/AppStateListener.swift b/Sources/Datadog/Core/System/AppStateListener.swift
@@ -20,7 +20,7 @@ internal struct AppStateHistory: Equatable {
     }
 
     var initialState: Snapshot
-    var changes: [Snapshot]
+    private(set) var changes: [Snapshot]
     // NOTE: RUMM-1064 changes.last.date > finalDate case isn't handled as not realistic
     var finalDate: Date
     var finalState: Snapshot {
@@ -30,6 +30,11 @@ internal struct AppStateHistory: Equatable {
         )
     }
 
+    mutating func add(change: Snapshot) {
+        changes.append(change)
+        changes.sort()
+    }
+
     /// Limits or extrapolates app state history to the given range
     /// This is useful when you record between 0...3t but you are concerned of t...2t only
     /// - Parameter range: if outside of `initialState` and `finalState`, it extrapolates; otherwise it limits
@@ -51,7 +56,7 @@ internal struct AppStateHistory: Equatable {
     var foregroundDuration: TimeInterval {
         var duration: TimeInterval = 0.0
         var lastActiveStartDate: Date?
-        let allEvents = [initialState] + changes.sorted() + [finalState]
+        let allEvents = [initialState] + changes + [finalState]
         for event in allEvents {
             if let startDate = lastActiveStartDate {
                 duration += event.date.timeIntervalSince(startDate)
@@ -95,13 +100,7 @@ internal protocol AppStateListening {
 internal class AppStateListener: AppStateListening {
     typealias Snapshot = AppStateHistory.Snapshot
 
-    private static var isActive: Bool {
-        return UIApplication.managedShared?.applicationState == .active
-    }
-
-    private static func currentState(with date: Date) -> Snapshot {
-        return Snapshot(isActive: AppStateListener.isActive, date: date)
-    }
+    static var shared = AppStateListener()
 
     private let dateProvider: DateProvider
     private var _appStateHistory: AppStateHistory
@@ -112,9 +111,21 @@ internal class AppStateListener: AppStateListening {
         return _appStateHistory
     }
 
+    private static var isAppActive: Bool {
+        if Thread.isMainThread {
+            return UIApplication.managedShared?.applicationState == .active
+        } else {
+            return DispatchQueue.main.sync {
+                UIApplication.managedShared?.applicationState == .active
+            }
+        }
+    }
+
     init(dateProvider: DateProvider = SystemDateProvider()) {
         self.dateProvider = dateProvider
-        let currentState = AppStateListener.currentState(with: dateProvider.currentDate())
+
+        let isAppActive = AppStateListener.isAppActive
+        let currentState = Snapshot(isActive: isAppActive, date: dateProvider.currentDate())
         _appStateHistory = AppStateHistory(
             initialState: currentState,
             changes: [],
@@ -128,13 +139,13 @@ internal class AppStateListener: AppStateListening {
     @objc
     private func appWillResignActive() {
         objc_sync_enter(self)
-        _appStateHistory.changes.append(Snapshot(isActive: false, date: dateProvider.currentDate()))
+        _appStateHistory.add(change: Snapshot(isActive: false, date: dateProvider.currentDate()))
         objc_sync_exit(self)
     }
     @objc
     private func appDidBecomeActive() {
         objc_sync_enter(self)
-        _appStateHistory.changes.append(Snapshot(isActive: true, date: dateProvider.currentDate()))
+        _appStateHistory.add(change: Snapshot(isActive: true, date: dateProvider.currentDate()))
         objc_sync_exit(self)
     }
 }
diff --git a/Sources/Datadog/URLSessionAutoInstrumentation/Interception/TaskInterception.swift b/Sources/Datadog/URLSessionAutoInstrumentation/Interception/TaskInterception.swift
@@ -27,7 +27,7 @@ internal class TaskInterception {
     init(
         request: URLRequest,
         isFirstParty: Bool,
-        appStateListener: AppStateListening = AppStateListener()
+        appStateListener: AppStateListening = AppStateListener.shared
     ) {
         self.identifier = UUID()
         self.request = request

diff --git a/...tadogTests/Datadog/URLSessionAutoInstrumentation/Interception/AppStateListenerTests.swift b/...tadogTests/Datadog/URLSessionAutoInstrumentation/Interception/AppStateListenerTests.swift
@@ -105,22 +105,38 @@ class AppStateHistoryTests: XCTestCase {
 
     func testLimitingWithChanges() {
         let startDate = Date.mockDecember15th2019At10AMUTC()
-        let history = AppStateHistory(
+        let firstChanges = (0...100).map { _ in
+            AppStateHistory.Snapshot(
+                isActive: Bool.random(),
+                date: startDate + TimeInterval.random(in: 0...1_000)
+            )
+        }
+        let lastChanges = (0...100).map { _ in
+            AppStateHistory.Snapshot(
+                isActive: Bool.random(),
+                date: startDate + TimeInterval.random(in: 2_000...3_000)
+            )
+        }
+        var history = AppStateHistory(
             initialState: .init(isActive: true, date: startDate),
-            changes: [
-                .init(isActive: false, date: startDate + 3.0),
-                .init(isActive: true, date: startDate + 6.0),
-            ],
+            changes: firstChanges + lastChanges,
             finalDate: startDate + 9.0
         )
+        history.add(change: .init(isActive: true, date: startDate + 1_200))
+        history.add(change: .init(isActive: false, date: startDate + 1_500))
+        history.add(change: .init(isActive: true, date: startDate + 1_700))
+
         let limitedHistory = history.take(
-            between: (startDate + 5.0)...(startDate + 10.0)
+            between: (startDate + 1_250)...(startDate + 1_750)
         )
 
         let expectedHistory = AppStateHistory(
-            initialState: .init(isActive: false, date: startDate + 5.0),
-            changes: [.init(isActive: true, date: startDate + 6.0)],
-            finalDate: startDate + 10.0
+            initialState: .init(isActive: true, date: startDate + 1_250),
+            changes: [
+                .init(isActive: false, date: startDate + 1_500),
+                .init(isActive: true, date: startDate + 1_700),
+            ],
+            finalDate: startDate + 1_750
         )
         XCTAssertEqual(limitedHistory, expectedHistory)
     }
@@ -192,25 +208,4 @@ class AppStateListenerTests: XCTestCase {
             XCTAssertFalse(listener.history.changes.isEmpty)
         }
     }
-
-    // objc_sync 100 -> 0.046sec
-    // objc_sync 1_000 -> 8.430sec
-    // DispatchQueue 100 -> 0.340sec
-    // DispatchQueue 1_000 -> 8.630sec
-    func testWhenManyAppStateListenersAreCalledFromDifferentThreads_thenTheyWork() {
-        let iterationCount = 100
-        let listeners = (0..<iterationCount).map { _ in AppStateListener() }
-        DispatchQueue.concurrentPerform(iterations: iterationCount) { iteration in
-            // write
-            let nc = NotificationCenter.default
-            nc.post(
-                name: (Bool.random() ?
-                        UIApplication.willResignActiveNotification :
-                        UIApplication.didBecomeActiveNotification),
-                object: nil
-            )
-            // read
-            XCTAssertFalse(listeners[iteration].history.changes.isEmpty)
-        }
-    }
 }