Add TTI/TTFR tracking for Activities & Fragments (#2)

Add missing metrics tracking:
- [Time To Interactive
(TTI)](https://medium.com/booking-com-development/measuring-mobile-apps-performance-in-production-726e7e84072f#ad4d)
- [Time To First Render
(TTFR)](https://medium.com/booking-com-development/measuring-mobile-apps-performance-in-production-726e7e84072f#f862)

Usage example is also added to the `sampleApp`

Author: smbduknow

README.md

@@ -16,9 +16,13 @@ flexible with re-using the monitoring approaches already existing in your produc
 Library supports collecting following performance metrics:
 - App Cold Startup Time
 - Rendering performance per Activity
+- Time to Interactive & Time to First Render per screen
 
 We recommend to read our blogpost ["Measuring mobile apps performance in production"](https://medium.com/booking-com-development/measuring-mobile-apps-performance-in-production-726e7e84072f) 
-first to get some idea on how performance metrics work and why those were chosen.
+first to get some idea on what are these performance metrics, how they work and why those were chosen.
+
+> NOTE: You can also refer to the [SampleApp](sampleApp/src/main/java/com/booking/perfsuite/app) 
+> in this repo to see a simplified example of how the library can be used in the real app
 
 ### Dependency
 
@@ -98,6 +102,55 @@ Then metrics will be represented as [`RenderingMetrics`](src/main/java/com/booki
 
 Even though we support collecting widely used slow & frozen frames we [strongly recommend relying on `totalFreezeTimeMs` as the main rendering metric](https://medium.com/booking-com-development/measuring-mobile-apps-performance-in-production-726e7e84072f#2d5d)
 
+### Collecting Screen Time to Interactive (TTI)
+
+Implement the callbacks invoked every time when screen's
+[Time To Interactive (TTI)](https://medium.com/booking-com-development/measuring-mobile-apps-performance-in-production-726e7e84072f#ad4d) &
+[Time To First Render (TTFR)](https://medium.com/booking-com-development/measuring-mobile-apps-performance-in-production-726e7e84072f#f862)
+metrics are collected:
+
+```kotlin
+object MyTtiListener : BaseTtiTracker.Listener {
+
+    override fun onScreenCreated(screen: String) {}
+
+    override fun onFirstFrameIsDrawn(screen: String, duration: Long) {
+        // Log or report TTFR metrics for specific screen in a preferable way
+    }
+    override fun onFirstUsableFrameIsDrawn(screen: String, duration: Long) {
+        // Log or report TTI metrics for specific screen in a preferable way
+    }
+}
+```
+
+Then instantiate TTI tracker in `Application#onCreate` before any activity is created and using this listener:
+
+```kotlin
+// keep instances globally accessible or inject as singletons using any preferable DI framework
+val ttiTracker = BaseTtiTracker(AppTtiListener)
+val viewTtiTracker = ViewTtiTracker(ttiTracker)
+
+class MyApplication : Application() {
+
+    override fun onCreate() {
+        super.onCreate()
+        ActivityTtfrHelper.register(this, viewTtiTracker)
+    }
+}
+```
+
+That will enable automatic TTFR collection for every Activity in the app.
+For TTI collection you'll need to call `viewTtiTracker.onScreenIsUsable(..)` manually from the Activity, 
+when the meaningful data is visible to the user e.g.:
+
+```kotlin
+// call this e.g. when the data is received from the backend,
+// progress bar stops spinning and screen is fully ready for the user
+viewTtiTracker.onScreenIsUsable(activity.componentName, rootContentView)
+```
+
+See the [SampleApp](sampleApp/src/main/java/com/booking/perfsuite/app) for a full working example
+
 ## Additional documentation
 - [Measuring mobile apps performance in production](https://medium.com/booking-com-development/measuring-mobile-apps-performance-in-production-726e7e84072f) 
 - [App Startup Time documentation by Google](https://developer.android.com/topic/performance/vitals/launch-time)

gradle/libs.versions.toml

@@ -9,6 +9,7 @@ androidx-appcompat = "1.6.1"
 [libraries]
 androidx-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "androidx-ktx" }
 androidx-appcompat = { group = "androidx.appcompat", name = "appcompat", version.ref = "androidx-appcompat" }
+androidx-fragment = { group = "androidx.fragment", name = "fragment", version.ref = "androidx-appcompat" }
 
 [plugins]
 kotlin = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }

perfsuite/build.gradle.kts

@@ -24,4 +24,5 @@ android {
 
 dependencies {
     implementation(libs.androidx.ktx)
+    implementation(libs.androidx.fragment)
 }

perfsuite/src/main/java/com/booking/perfsuite/tti/BaseTtiTracker.kt

@@ -0,0 +1,116 @@
+package com.booking.perfsuite.tti
+
+import androidx.annotation.UiThread
+import com.booking.perfsuite.internal.nowMillis
+
+/**
+ * The most basic TTFR/TTI tracking implementation.
+ * This class can be used with any possible screen implementation
+ * (Activities, Fragments, Views, Jetpack Compose and etc.).
+ *
+ * To work properly it requires that methods are called respectively to the screen lifecycle events:
+ * 1. Call [onScreenCreated] at the earliest possible moment of the screen instantiation
+ * 2. Then call [onScreenViewIsReady] when the first screen frame is shown to the user,
+ *    that will indicate that TTFR metric is collected
+ * 3. Optionally call [onScreenIsUsable] when the usable content is shown to the user,
+ *    that will indicate that TTI metric is collected
+ *
+ * For more details please refer to the documentation:
+ * https://github.com/bookingcom/perfsuite-android?tab=readme-ov-file#additional-documentation
+ *
+ * @param listener implementation is used to handle screen TTI\TTFR metrics when they are ready
+ */
+@UiThread
+public class BaseTtiTracker(
+    private val listener: Listener
+) {
+
+    private val screenCreationTimestamp = HashMap<String, Long>()
+
+    /**
+     * Call this method immediately on screen creation as early as possible
+     *
+     * @param screen - unique screen identifier
+     * @param timestamp - the time the screen was created at.
+     */
+    public fun onScreenCreated(screen: String, timestamp: Long = nowMillis()) {
+        screenCreationTimestamp[screen] = timestamp
+        listener.onScreenCreated(screen)
+    }
+
+    /**
+     * Call this method when screen is rendered for the first time
+     *
+     * @param screen - unique screen identifier
+     */
+    public fun onScreenViewIsReady(screen: String) {
+        screenCreationTimestamp[screen]?.let { creationTimestamp ->
+            val duration = nowMillis() - creationTimestamp
+            listener.onFirstFrameIsDrawn(screen, duration)
+        }
+    }
+
+    /**
+     * Call this method when the screen is ready for user interaction
+     * (e.g. all data is ready and meaningful content is shown).
+     *
+     * The method is optional, whenever it is not called TTI won't be measured
+     *
+     * @param screen - unique screen identifier
+     */
+    public fun onScreenIsUsable(screen: String) {
+        screenCreationTimestamp[screen]?.let { creationTimestamp ->
+            val duration = nowMillis() - creationTimestamp
+            listener.onFirstUsableFrameIsDrawn(screen, duration)
+            screenCreationTimestamp.remove(screen)
+        }
+    }
+
+    /**
+     * Call this when user leaves the screen.
+     *
+     * This prevent us from producing outliers and avoid tracking cheap screen transitions
+     * (e.g. back navigation, when the screen is already created in memory),
+     * so we're able to track only real screen creation performance
+     */
+    public fun onScreenStopped(screen: String) {
+        screenCreationTimestamp.remove(screen)
+    }
+
+    /**
+     * Returns true if the screen is still in the state of collecting metrics.
+     * When result is false,that means that both TTFR/TTI metrics were already collected or
+     * discarded for any reason
+     */
+    public fun isScreenEnabledForTracking(screen: String): Boolean =
+        screenCreationTimestamp.containsKey(screen)
+
+    /**
+     * Listener interface providing TTFR/TTI metrics when they're ready
+     */
+    public interface Listener {
+
+        /**
+         * Called as early as possible after the screen [screen] is created.
+         *
+         * @param screen - screen key
+         */
+        public fun onScreenCreated(screen: String)
+
+        /**
+         * Called when the very first screen frame is drawn
+         *
+         * @param screen - screen key
+         * @param duration - elapsed time since screen's creation till the first frame is drawn
+         */
+        public fun onFirstFrameIsDrawn(screen: String, duration: Long)
+
+        /**
+         * Called when the first usable/meaningful screen frame is drawn
+         *
+         * @param screen - screen key
+         * @param duration - elapsed time since screen's creation till the usable frame is drawn
+         */
+        public fun onFirstUsableFrameIsDrawn(screen: String, duration: Long)
+    }
+}

perfsuite/src/main/java/com/booking/perfsuite/tti/ViewTtiTracker.kt

@@ -0,0 +1,76 @@
+package com.booking.perfsuite.tti
+
+import android.view.View
+import androidx.annotation.UiThread
+import com.booking.perfsuite.internal.doOnNextDraw
+
+/**
+ * Android View-based implementation of TTI\TTFR tracking. This class should be used with screens
+ * which are rendered using Android [View] class (Activities, Fragments, Views).
+ *
+ * For Android Views we always should measure time until the actual draw happens
+ * and [View.onDraw] is called.
+ * That's why when [onScreenViewIsReady] or [onScreenIsUsable] are called, the tracker actually
+ * waits until the next frame draw before finish collecting TTFR/TTI metrics.
+ *
+ * Technically this is a wrapper around [BaseTtiTracker] which helps to collect metrics respectively to
+ * how [View] rendering works.
+ * Therefore, please use [BaseTtiTracker] directly in case of using canvas drawing,
+ * Jetpack Compose or any other approach which is not based on Views.
+ *
+ * See also [com.booking.perfsuite.tti.helpers.ActivityTtfrHelper] and
+ * [com.booking.perfsuite.tti.helpers.FragmentTtfrHelper] for automatic TTFR collection
+ * in Activities and Fragments.
+ */
+@UiThread
+public class ViewTtiTracker(private val tracker: BaseTtiTracker) {
+
+    /**
+     * Call this method immediately on screen creation as early as possible
+     *
+     * @param screen - unique screen identifier
+     */
+    public fun onScreenCreated(screen: String) {
+        tracker.onScreenCreated(screen)
+    }
+
+    /**
+     * Call this when screen View is ready but it is not drawn yet
+     *
+     * @param screen - unique screen identifier
+     * @param rootView - root view of the screen, metric is ready when this view is next drawn
+     */
+    public fun onScreenViewIsReady(screen: String, rootView: View) {
+        if (tracker.isScreenEnabledForTracking(screen)) {
+            rootView.doOnNextDraw { tracker.onScreenViewIsReady(screen) }
+        }
+    }
+
+    /**
+     * Call this when the screen View is ready for user interaction.
+     * Only the first call after screen creation is considered, repeat calls are ignored
+     *
+     * @see BaseTtiTracker.onScreenIsUsable
+     *
+     * @param screen - unique screen identifier
+     * @param rootView - root view of the screen, metric is ready when this view is next drawn
+     *
+     *
+     */
+    public fun onScreenIsUsable(screen: String, rootView: View) {
+        if (tracker.isScreenEnabledForTracking(screen)) {
+            rootView.doOnNextDraw { tracker.onScreenIsUsable(screen) }
+        }
+    }
+
+    /**
+     * Call this when user leaves the screen.
+     *
+     * This prevent us from tracking cheap screen transitions (e.g. back navigation,
+     * when the screen is already created in memory), so we're able to track
+     * only real screen creation performance, removing outliers
+     */
+    public fun onScreenStopped(screen: String) {
+        tracker.onScreenStopped(screen)
+    }
+}

perfsuite/src/main/java/com/booking/perfsuite/tti/helpers/ActivityTtfrHelper.kt

@@ -0,0 +1,65 @@
+package com.booking.perfsuite.tti.helpers
+
+import android.app.Activity
+import android.app.Application
+import android.app.Application.ActivityLifecycleCallbacks
+import android.os.Bundle
+import com.booking.perfsuite.tti.ViewTtiTracker
+
+/**
+ * This class helps to automatically track TTFR metric for every activity by handling
+ * [android.app.Application.ActivityLifecycleCallbacks]
+ *
+ * @param tracker TTI tracker instance
+ * @param screenNameProvider function used to generate unique screen name/identifier for activity.
+ *      If it returns null, then activity won't be tracked.
+ *      By default it uses the implementation based on Activity's class name
+ */
+public class ActivityTtfrHelper(
+    private val tracker: ViewTtiTracker,
+    private val screenNameProvider: (Activity) -> String? = { it.javaClass.name }
+) : ActivityLifecycleCallbacks {
+
+    public companion object {
+
+        /**
+         * Registers [ActivityTtfrHelper] instance with the app as
+         * [android.app.Application.ActivityLifecycleCallbacks] to collect TTFR metrics for
+         * every activity
+         *
+         * Call this method at the app startup, before the first activity is created
+         *
+         * @param application current [Application] instance
+         * @param tracker configured for the app [ViewTtiTracker] instance
+         */
+        @JvmStatic
+        public fun register(application: Application, tracker: ViewTtiTracker) {
+            val activityHelper = ActivityTtfrHelper(tracker)
+            application.registerActivityLifecycleCallbacks(activityHelper)
+        }
+    }
+
+    override fun onActivityPreCreated(activity: Activity, savedInstanceState: Bundle?) {
+        val screenKey = screenNameProvider(activity) ?: return
+        tracker.onScreenCreated(screenKey)
+    }
+
+    override fun onActivityStarted(activity: Activity) {
+        val screenKey = screenNameProvider(activity) ?: return
+        val rootView = activity.window.decorView
+        tracker.onScreenViewIsReady(screenKey, rootView)
+    }
+
+    override fun onActivityStopped(activity: Activity) {
+        val screenKey = screenNameProvider(activity) ?: return
+        tracker.onScreenStopped(screenKey)
+    }
+
+    override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) { }
+    override fun onActivityResumed(activity: Activity) { }
+    override fun onActivityPaused(activity: Activity) { }
+    override fun onActivitySaveInstanceState(activity: Activity, outState: Bundle) { }
+    override fun onActivityDestroyed(activity: Activity) { }
+
+
+}

perfsuite/src/main/java/com/booking/perfsuite/tti/helpers/FragmentTtfrHelper.kt

@@ -0,0 +1,42 @@
+package com.booking.perfsuite.tti.helpers
+
+import android.os.Bundle
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.FragmentManager
+import com.booking.perfsuite.tti.ViewTtiTracker
+
+/**
+ * This class helps to automatically track TTFR metric for every fragment
+ * within the particular activity or particular parent fragment by handling
+ * [androidx.fragment.app.FragmentManager.FragmentLifecycleCallbacks]
+ *
+ * @param tracker TTI tracker instance
+ * @param screenNameProvider function used to generate unique screen name/identifier for fragment.
+ *      If it returns null, then fragment won't be tracked.
+ *      By default it uses the implementation based on Fragment's class name
+ */
+public class FragmentTtfrHelper(
+    private val tracker: ViewTtiTracker,
+    private val screenNameProvider: (Fragment) -> String? = { it.javaClass.name }
+) : FragmentManager.FragmentLifecycleCallbacks() {
+
+    override fun onFragmentPreCreated(
+        fm: FragmentManager,
+        fragment: Fragment,
+        savedInstanceState: Bundle?
+    ) {
+        val screenKey = screenNameProvider(fragment) ?: return
+        tracker.onScreenCreated(screenKey)
+    }
+
+    override fun onFragmentStarted(fm: FragmentManager, fragment: Fragment) {
+        val screenKey = screenNameProvider(fragment) ?: return
+        val rootView = fragment.view ?: return
+        tracker.onScreenViewIsReady(screenKey, rootView)
+    }
+
+    override fun onFragmentStopped(fm: FragmentManager, fragment: Fragment) {
+        val screenKey = screenNameProvider(fragment) ?: return
+        tracker.onScreenStopped(screenKey)
+    }
+}