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hamorillohamorillo
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Merge pull request #3372 from DataDog/hector.morilloprieto/RUM-15139
RUM-15139: Use rebased sessionReplaySampleRate for deterministic Session Replay sampling
2 parents 5ecd159 + 294bfe6 commit 6bc1364

14 files changed

Lines changed: 464 additions & 357 deletions

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‎dd-sdk-android-internal/api/apiSurface‎

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@@ -164,6 +164,10 @@ sealed class com.datadog.android.internal.profiling.ProfilerStopEvent
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constructor(TTIDRumContext? = null)
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data class com.datadog.android.internal.profiling.TTIDRumContext
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constructor(String, String, String, String?, String?, String?)
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object com.datadog.android.internal.sampling.DeterministicSampling
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fun combinedSampleRate(Float, Float): Float
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object com.datadog.android.internal.sampling.SessionSamplingIdProvider
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fun provideId(String): ULong
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interface com.datadog.android.internal.system.BuildSdkVersionProvider
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val version: Int
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val isAtLeastN: Boolean

‎dd-sdk-android-internal/api/dd-sdk-android-internal.api‎

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@@ -310,6 +310,16 @@ public final class com/datadog/android/internal/profiling/TTIDRumContext {
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public fun toString ()Ljava/lang/String;
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}
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public final class com/datadog/android/internal/sampling/DeterministicSampling {
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public static final field INSTANCE Lcom/datadog/android/internal/sampling/DeterministicSampling;
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public final fun combinedSampleRate (FF)F
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}
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public final class com/datadog/android/internal/sampling/SessionSamplingIdProvider {
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public static final field INSTANCE Lcom/datadog/android/internal/sampling/SessionSamplingIdProvider;
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public final fun provideId-I7RO_PI (Ljava/lang/String;)J
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}
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public abstract interface class com/datadog/android/internal/system/BuildSdkVersionProvider {
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public static final field Companion Lcom/datadog/android/internal/system/BuildSdkVersionProvider$Companion;
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public abstract fun getVersion ()I

‎dd-sdk-android-internal/src/main/java/com/datadog/android/internal/sampling/DeterministicSampling.kt‎

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/*
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* Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
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* This product includes software developed at Datadog (https://www.datadoghq.com/).
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* Copyright 2016-Present Datadog, Inc.
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*/
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package com.datadog.android.internal.sampling
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/**
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* Utilities for deterministic sampling calculations.
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*/
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object DeterministicSampling {
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private const val SAMPLE_ALL_RATE: Float = 100f
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/**
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* Returns the effective sampling rate when a child feature's [featureSampleRate] is applied
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* on top of a parent session's [rumSessionSampleRate].
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*
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* The combined rate represents the probability that both the session AND the child feature
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* are sampled in, preserving the deterministic guarantee: any session that passes the combined
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* threshold is guaranteed to have also passed the session-level threshold.
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*
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* @param rumSessionSampleRate The RUM session sampling rate (0–100).
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* @param featureSampleRate The child feature sampling rate (0–100).
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* @return The effective combined rate, clamped to [0, 100].
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*/
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fun combinedSampleRate(rumSessionSampleRate: Float, featureSampleRate: Float): Float =
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(rumSessionSampleRate * featureSampleRate / SAMPLE_ALL_RATE)
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.coerceIn(0f, SAMPLE_ALL_RATE)
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}

‎dd-sdk-android-internal/src/main/java/com/datadog/android/internal/sampling/SessionSamplingIdProvider.kt‎

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@@ -0,0 +1,28 @@
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/*
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* Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
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* This product includes software developed at Datadog (https://www.datadoghq.com/).
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* Copyright 2016-Present Datadog, Inc.
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*/
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package com.datadog.android.internal.sampling
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private const val HEX_RADIX = 16
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/**
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* Extracts a numeric identifier from a RUM session ID for use as input to a [DeterministicSampler].
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*/
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object SessionSamplingIdProvider {
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/**
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* Returns the last hyphen-delimited segment of [sessionId] parsed as an unsigned hexadecimal
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* long, or `0` if the input is malformed or the segment is not valid hex.
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*
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* For a UUID `aaaaaaaa-bbbb-cccc-dddd-1234567890ab` this returns `0x1234567890ab`.
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*/
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fun provideId(sessionId: String): ULong {
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return sessionId.split('-')
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.lastOrNull()
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?.toULongOrNull(HEX_RADIX)
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?: 0uL
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}
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}

‎dd-sdk-android-internal/src/test/java/com/datadog/android/internal/sampling/DeterministicSamplingTest.kt‎

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/*
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* Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
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* This product includes software developed at Datadog (https://www.datadoghq.com/).
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* Copyright 2016-Present Datadog, Inc.
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*/
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package com.datadog.android.internal.sampling
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import com.datadog.android.internal.forge.Configurator
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import fr.xgouchet.elmyr.annotation.FloatForgery
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import fr.xgouchet.elmyr.junit5.ForgeConfiguration
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import fr.xgouchet.elmyr.junit5.ForgeExtension
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import org.assertj.core.api.Assertions.assertThat
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import org.junit.jupiter.api.Test
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import org.junit.jupiter.api.extension.ExtendWith
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@ExtendWith(ForgeExtension::class)
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@ForgeConfiguration(Configurator::class)
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internal class DeterministicSamplingTest {
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@Test
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fun `M return combined rate W combinedSampleRate() {valid rates}`() {
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assertThat(DeterministicSampling.combinedSampleRate(50f, 20f)).isEqualTo(10f)
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}
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@Test
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fun `M return 0 W combinedSampleRate() {featureRate is 0}`(
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@FloatForgery(min = 0f, max = 100f) sessionRate: Float
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) {
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assertThat(DeterministicSampling.combinedSampleRate(sessionRate, 0f)).isEqualTo(0f)
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}
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@Test
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fun `M return 0 W combinedSampleRate() {sessionRate is 0}`(
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@FloatForgery(min = 0f, max = 100f) featureRate: Float
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) {
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assertThat(DeterministicSampling.combinedSampleRate(0f, featureRate)).isEqualTo(0f)
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}
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@Test
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fun `M return featureRate W combinedSampleRate() {sessionRate is 100}`() {
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assertThat(DeterministicSampling.combinedSampleRate(100f, 75f)).isEqualTo(75f)
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}
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@Test
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fun `M return sessionRate W combinedSampleRate() {featureRate is 100}`() {
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assertThat(DeterministicSampling.combinedSampleRate(75f, 100f)).isEqualTo(75f)
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}
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@Test
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fun `M return 100 W combinedSampleRate() {both rates are 100}`() {
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assertThat(DeterministicSampling.combinedSampleRate(100f, 100f)).isEqualTo(100f)
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}
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@Test
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fun `M return product divided by 100 W combinedSampleRate() {random valid rates}`(
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@FloatForgery(min = 0f, max = 100f) sessionRate: Float,
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@FloatForgery(min = 0f, max = 100f) featureRate: Float
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) {
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val expected = sessionRate * featureRate / 100f
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assertThat(DeterministicSampling.combinedSampleRate(sessionRate, featureRate)).isEqualTo(expected)
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}
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@Test
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fun `M clamp to 100 W combinedSampleRate() {rates exceed valid range}`() {
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assertThat(DeterministicSampling.combinedSampleRate(200f, 100f)).isEqualTo(100f)
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}
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@Test
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fun `M clamp to 0 W combinedSampleRate() {negative rate}`() {
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assertThat(DeterministicSampling.combinedSampleRate(-50f, 50f)).isEqualTo(0f)
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}
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}

features/dd-sdk-android-rum/src/test/kotlin/com/datadog/android/rum/internal/sampling/SessionSamplingIdProviderTest.kt renamed to dd-sdk-android-internal/src/test/java/com/datadog/android/internal/sampling/SessionSamplingIdProviderTest.kt

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@@ -4,7 +4,7 @@
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* Copyright 2016-Present Datadog, Inc.
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*/
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7-
package com.datadog.android.rum.internal.sampling
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package com.datadog.android.internal.sampling
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import org.assertj.core.api.Assertions.assertThat
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import org.junit.jupiter.api.Test

‎detekt_custom_safe_calls.yml‎

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@@ -1135,6 +1135,7 @@ datadog:
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- "kotlin.Double.toInt()"
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- "kotlin.Double.toLong()"
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- "kotlin.Double.toULong()"
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- "kotlin.Float.coerceIn(kotlin.Float, kotlin.Float)"
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- "kotlin.Float.fromBits(kotlin.Int)"
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- "kotlin.Float.percent()"
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- "kotlin.Float.roundToInt()"

‎features/dd-sdk-android-rum/src/main/kotlin/com/datadog/android/rum/Rum.kt‎

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@@ -17,12 +17,12 @@ import com.datadog.android.api.feature.FeatureSdkCore
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import com.datadog.android.core.InternalSdkCore
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import com.datadog.android.core.sampling.DeterministicSampler
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import com.datadog.android.core.sampling.RateBasedSampler
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import com.datadog.android.internal.sampling.SessionSamplingIdProvider
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import com.datadog.android.rum.internal.RumAnonymousIdentifierManager
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import com.datadog.android.rum.internal.RumFeature
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import com.datadog.android.rum.internal.domain.scope.RumVitalAppLaunchEventHelper
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import com.datadog.android.rum.internal.metric.SessionEndedMetricDispatcher
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import com.datadog.android.rum.internal.monitor.DatadogRumMonitor
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import com.datadog.android.rum.internal.sampling.SessionSamplingIdProvider
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import com.datadog.android.rum.internal.startup.RumAppStartupTelemetryReporter
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import com.datadog.android.rum.internal.startup.RumSessionScopeStartupManager
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import com.datadog.android.telemetry.internal.TelemetryEventHandler

‎features/dd-sdk-android-rum/src/main/kotlin/com/datadog/android/rum/internal/domain/RumContext.kt‎

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@@ -50,6 +50,7 @@ internal data class RumContext(
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companion object {
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val NULL_UUID = UUID(0, 0).toString()
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const val SAMPLE_ALL_RATE: Float = 100f
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// be careful when changing values below, they may be indirectly referenced (as string
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// literal) from other modules

‎features/dd-sdk-android-rum/src/main/kotlin/com/datadog/android/rum/internal/domain/scope/RumSessionScope.kt‎

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@@ -65,6 +65,7 @@ internal class RumSessionScope(
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6666
internal var sessionId = RumContext.NULL_UUID
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internal var sessionState: State = State.NOT_TRACKED
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internal val sessionSampleRate: Float = sessionSampler.getSampleRate() ?: RumContext.SAMPLE_ALL_RATE
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private var startReason: StartReason = StartReason.USER_APP_LAUNCH
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internal var isActive: Boolean = true
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private val sessionStartNs = AtomicLong(sdkCore.timeProvider.getDeviceElapsedTimeNanos())
@@ -88,7 +89,7 @@ internal class RumSessionScope(
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memoryVitalMonitor = memoryVitalMonitor,
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frameRateVitalMonitor = frameRateVitalMonitor,
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applicationDisplayed = applicationDisplayed,
91-
sampleRate = sessionSampler.getSampleRate() ?: 100f,
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sampleRate = sessionSampleRate,
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initialResourceIdentifier = networkSettledResourceIdentifier,
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slowFramesListener = slowFramesListener,
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lastInteractionIdentifier = lastInteractionIdentifier,
@@ -275,7 +276,7 @@ internal class RumSessionScope(
275276
renewSession(event.eventTime, StartReason.MAX_DURATION)
276277
}
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278-
updateSessionStateForSessionReplay(sessionState, sessionId)
279+
updateSessionStateForSessionReplay(sessionId)
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}
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private fun renewSession(time: Time, reason: StartReason) {
@@ -298,13 +299,16 @@ internal class RumSessionScope(
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sessionListener?.onSessionStarted(sessionId, !keepSession)
299300
}
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301-
private fun updateSessionStateForSessionReplay(state: State, sessionId: String) {
302-
val keepSession = (state == State.TRACKED)
302+
private fun updateSessionStateForSessionReplay(sessionId: String) {
303303
sdkCore.getFeature(Feature.SESSION_REPLAY_FEATURE_NAME)?.sendEvent(
304304
mapOf(
305305
SESSION_REPLAY_BUS_MESSAGE_TYPE_KEY to RUM_SESSION_RENEWED_BUS_MESSAGE,
306-
RUM_KEEP_SESSION_BUS_MESSAGE_KEY to keepSession,
307-
RUM_SESSION_ID_BUS_MESSAGE_KEY to sessionId
306+
RUM_SESSION_ID_BUS_MESSAGE_KEY to sessionId,
307+
RUM_SESSION_SAMPLE_RATE_BUS_MESSAGE_KEY to sessionSampleRate,
308+
// Kept for backward compatibility with older Session Replay modules that
309+
// don't yet consume sessionSampleRate.
310+
// RUM-15962: Remove with SDK v4 release (RUM-13454).
311+
RUM_KEEP_SESSION_BUS_MESSAGE_KEY to (sessionState == State.TRACKED)
308312
)
309313
)
310314
}
@@ -315,8 +319,11 @@ internal class RumSessionScope(
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316320
internal const val SESSION_REPLAY_BUS_MESSAGE_TYPE_KEY = "type"
317321
internal const val RUM_SESSION_RENEWED_BUS_MESSAGE = "rum_session_renewed"
318-
internal const val RUM_KEEP_SESSION_BUS_MESSAGE_KEY = "keepSession"
319322
internal const val RUM_SESSION_ID_BUS_MESSAGE_KEY = "sessionId"
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324+
// RUM-15962: Remove with SDK v4 release (RUM-13454).
325+
internal const val RUM_KEEP_SESSION_BUS_MESSAGE_KEY = "keepSession"
326+
internal const val RUM_SESSION_SAMPLE_RATE_BUS_MESSAGE_KEY = "sessionSampleRate"
320327
internal val DEFAULT_SESSION_INACTIVITY_NS = TimeUnit.MINUTES.toNanos(15)
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internal val DEFAULT_SESSION_MAX_DURATION_NS = TimeUnit.HOURS.toNanos(4)
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}

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