RUM-16664: Centralize startup scenario classification in RumStartupScenario.build()

Author: sbarrio

features/dd-sdk-android-rum/src/main/kotlin/com/datadog/android/rum/internal/startup/RumAppStartupDetector.kt

@@ -20,6 +20,13 @@ internal interface RumAppStartupDetector {
          */
         fun onAppStartupDetected(scenario: RumStartupScenario)
         fun onNextActivityCreated(pendingScenario: RumStartupScenario, activity: Activity)
+
+        /**
+         * Called when an Activity is destroyed. Listeners that hold per-activity resources
+         * (e.g. a [com.datadog.android.rum.startup.RumFirstDrawTimeReporter.Handle]) should
+         * release them here to avoid memory leaks.
+         */
+        fun onActivityDestroyed(activity: Activity) = Unit
     }
 
     fun destroy()

features/dd-sdk-android-rum/src/main/kotlin/com/datadog/android/rum/internal/startup/RumAppStartupDetectorImpl.kt

@@ -16,7 +16,6 @@ import com.datadog.android.rum.startup.AppStartupActivityPredicate
 import java.lang.ref.WeakReference
 import java.util.Collections
 import java.util.WeakHashMap
-import kotlin.time.Duration.Companion.seconds
 
 internal class RumAppStartupDetectorImpl(
     private val application: Application,
@@ -54,6 +53,7 @@ internal class RumAppStartupDetectorImpl(
     override fun onActivityDestroyed(activity: Activity) {
         numberOfActivities--
         trackedActivities.remove(activity)
+        listener.onActivityDestroyed(activity)
 
         if (numberOfActivities == 0) {
             isChangingConfigurations = activity.isChangingConfigurations
@@ -102,34 +102,13 @@ internal class RumAppStartupDetectorImpl(
 
         if (isFirstTrackedActivityWithNoPendingStartup) {
             val processStartTime = appStartupTime()
-
-            val gapNs = now.nanoTime - processStartTime.nanoTime
-            val hasSavedInstanceStateBundle = savedInstanceState != null
-            val weakActivity = WeakReference(activity)
-
-            val scenario = if (isFirstActivityForProcess) {
-                if (gapNs > START_GAP_THRESHOLD_NS) {
-                    RumStartupScenario.WarmFirstActivity(
-                        hasSavedInstanceStateBundle = hasSavedInstanceStateBundle,
-                        activity = weakActivity,
-                        appStartActivityOnCreateGapNs = gapNs,
-                        initialTime = now
-                    )
-                } else {
-                    RumStartupScenario.Cold(
-                        hasSavedInstanceStateBundle = hasSavedInstanceStateBundle,
-                        activity = weakActivity,
-                        appStartActivityOnCreateGapNs = gapNs,
-                        initialTime = processStartTime
-                    )
-                }
-            } else {
-                RumStartupScenario.WarmAfterActivityDestroyed(
-                    hasSavedInstanceStateBundle = hasSavedInstanceStateBundle,
-                    activity = weakActivity,
-                    initialTime = now
-                )
-            }
+            val scenario = RumStartupScenario.build(
+                isFirstActivityForProcess = isFirstActivityForProcess,
+                hasSavedInstanceStateBundle = savedInstanceState != null,
+                activity = WeakReference(activity),
+                processStartTime = processStartTime,
+                activityOnCreateTime = now
+            )
 
             pendingScenario = scenario
             listener.onAppStartupDetected(scenario)
@@ -157,7 +136,4 @@ internal class RumAppStartupDetectorImpl(
         application.unregisterActivityLifecycleCallbacks(this)
     }
 
-    companion object {
-        private val START_GAP_THRESHOLD_NS = 10.seconds.inWholeNanoseconds
-    }
 }

features/dd-sdk-android-rum/src/main/kotlin/com/datadog/android/rum/internal/startup/RumStartupScenario.kt

@@ -9,6 +9,7 @@ package com.datadog.android.rum.internal.startup
 import android.app.Activity
 import com.datadog.android.rum.internal.domain.Time
 import java.lang.ref.WeakReference
+import kotlin.time.Duration.Companion.seconds
 
 internal sealed interface RumStartupScenario {
     val initialTime: Time
@@ -34,6 +35,49 @@ internal sealed interface RumStartupScenario {
         override val activity: WeakReference<Activity>,
         override val initialTime: Time
     ) : RumStartupScenario
+
+    companion object {
+        internal val START_GAP_THRESHOLD_NS = 10.seconds.inWholeNanoseconds
+
+        /**
+         * Builds the correct [RumStartupScenario] subtype from the raw timing data captured at
+         * Activity creation time. This is the single source of truth for the Cold / WarmFirstActivity
+         * / WarmAfterActivityDestroyed classification, shared by [RumAppStartupDetectorImpl] and
+         * [com.datadog.android.rum.internal.RumFeature].
+         */
+        fun build(
+            isFirstActivityForProcess: Boolean,
+            hasSavedInstanceStateBundle: Boolean,
+            activity: WeakReference<Activity>,
+            processStartTime: Time,
+            activityOnCreateTime: Time
+        ): RumStartupScenario {
+            return if (isFirstActivityForProcess) {
+                val gapNs = activityOnCreateTime.nanoTime - processStartTime.nanoTime
+                if (gapNs > START_GAP_THRESHOLD_NS) {
+                    WarmFirstActivity(
+                        hasSavedInstanceStateBundle = hasSavedInstanceStateBundle,
+                        activity = activity,
+                        appStartActivityOnCreateGapNs = gapNs,
+                        initialTime = activityOnCreateTime
+                    )
+                } else {
+                    Cold(
+                        hasSavedInstanceStateBundle = hasSavedInstanceStateBundle,
+                        activity = activity,
+                        appStartActivityOnCreateGapNs = gapNs,
+                        initialTime = processStartTime
+                    )
+                }
+            } else {
+                WarmAfterActivityDestroyed(
+                    hasSavedInstanceStateBundle = hasSavedInstanceStateBundle,
+                    activity = activity,
+                    initialTime = activityOnCreateTime
+                )
+            }
+        }
+    }
 }
 
 internal val RumStartupScenario.name: String get() = when (this) {

features/dd-sdk-android-rum/src/test/kotlin/com/datadog/android/rum/internal/startup/RumAppStartupDetectorImplTest.kt

@@ -195,6 +195,7 @@ internal class RumAppStartupDetectorImplTest {
                 )
             )
         }
+        verify(listener).onActivityDestroyed(activity)
         verifyNoMoreInteractions(listener)
     }
 
@@ -236,6 +237,7 @@ internal class RumAppStartupDetectorImplTest {
                 appStartActivityOnCreateGapNs = 3.seconds.inWholeNanoseconds
             )
         )
+        verify(listener).onActivityDestroyed(activity)
         verifyNoMoreInteractions(listener)
     }
 
@@ -342,6 +344,7 @@ internal class RumAppStartupDetectorImplTest {
             )
         }
 
+        verify(listener).onActivityDestroyed(activity)
         verifyNoMoreInteractions(listener)
     }
 
@@ -424,6 +427,8 @@ internal class RumAppStartupDetectorImplTest {
             )
         }
 
+        verify(listener).onActivityDestroyed(activity2)
+        verify(listener).onActivityDestroyed(activity)
         verifyNoMoreInteractions(listener)
     }
 
@@ -478,6 +483,7 @@ internal class RumAppStartupDetectorImplTest {
             )
         )
 
+        verify(listener).onActivityDestroyed(interstitialActivity)
         verifyNoMoreInteractions(listener)
     }
 
@@ -670,6 +676,7 @@ internal class RumAppStartupDetectorImplTest {
             )
         )
 
+        verify(listener).onActivityDestroyed(activity1)
         verifyNoMoreInteractions(listener)
     }