Add AndroidClock which overrides nanoTime with `SystemClock.elaps…

android-agent/build.gradle.kts

@@ -5,6 +5,11 @@ plugins {
 
 android {
     namespace = "io.opentelemetry.android.agent"
+
+    testOptions {
+        unitTests.isReturnDefaultValues = true
+        unitTests.isIncludeAndroidResources = true
+    }
 }
 
 dependencies {

android-agent/src/main/kotlin/io/opentelemetry/android/agent/session/SessionIdTimeoutHandler.kt

@@ -6,6 +6,7 @@
 package io.opentelemetry.android.agent.session
 
 import io.opentelemetry.android.Incubating
+import io.opentelemetry.android.common.internal.tools.time.AndroidClock
 import io.opentelemetry.android.internal.services.applifecycle.ApplicationStateListener
 import io.opentelemetry.sdk.common.Clock
 import kotlin.time.Duration
@@ -37,7 +38,7 @@ internal class SessionIdTimeoutHandler(
     // for testing
     @OptIn(Incubating::class)
     internal constructor(sessionConfig: SessionConfig) : this(
-        Clock.getDefault(),
+        AndroidClock.INSTANCE,
         sessionConfig.backgroundInactivityTimeout,
     )
 

android-agent/src/main/kotlin/io/opentelemetry/android/agent/session/SessionManager.kt

@@ -6,6 +6,7 @@
 package io.opentelemetry.android.agent.session
 
 import io.opentelemetry.android.Incubating
+import io.opentelemetry.android.common.internal.tools.time.AndroidClock
 import io.opentelemetry.android.session.Session
 import io.opentelemetry.android.session.SessionObserver
 import io.opentelemetry.android.session.SessionProvider
@@ -17,7 +18,7 @@ import kotlin.random.Random
 import kotlin.time.Duration
 
 internal class SessionManager(
-    private val clock: Clock = Clock.getDefault(),
+    private val clock: Clock = AndroidClock.INSTANCE,
     private val sessionStorage: SessionStorage = InMemorySessionStorage(),
     private val timeoutHandler: SessionIdTimeoutHandler,
     private val idGenerator: SessionIdGenerator = DefaultSessionIdGenerator(Random.Default),

common/api/common.api

@@ -86,6 +86,18 @@ public final class io/opentelemetry/android/common/internal/features/networkattr
 	public static fun values ()[Lio/opentelemetry/android/common/internal/features/networkattributes/data/NetworkState;
 }
 
+public final class io/opentelemetry/android/common/internal/tools/time/AndroidClock : io/opentelemetry/sdk/common/Clock {
+	public static final field Companion Lio/opentelemetry/android/common/internal/tools/time/AndroidClock$Companion;
+	public fun <init> ()V
+	public static final fun getINSTANCE ()Lio/opentelemetry/android/common/internal/tools/time/AndroidClock;
+	public fun nanoTime ()J
+	public fun now ()J
+}
+
+public final class io/opentelemetry/android/common/internal/tools/time/AndroidClock$Companion {
+	public final fun getINSTANCE ()Lio/opentelemetry/android/common/internal/tools/time/AndroidClock;
+}
+
 public abstract interface class io/opentelemetry/android/common/internal/tools/time/SystemTime {
 	public static final field Companion Lio/opentelemetry/android/common/internal/tools/time/SystemTime$Companion;
 	public abstract fun getCurrentTimeMillis ()J

common/build.gradle.kts

@@ -11,6 +11,11 @@ android {
     defaultConfig {
         consumerProguardFiles("consumer-rules.pro")
     }
+
+    testOptions {
+        unitTests.isReturnDefaultValues = true
+        unitTests.isIncludeAndroidResources = true
+    }
 }
 
 dependencies {

common/src/main/java/io/opentelemetry/android/common/internal/tools/time/AndroidClock.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.android.common.internal.tools.time
+
+import android.os.SystemClock
+import io.opentelemetry.sdk.common.Clock
+import javax.annotation.concurrent.ThreadSafe
+
+@ThreadSafe
+class AndroidClock internal constructor(
+    timeSinceEpochMillisProvider: () -> Long = System::currentTimeMillis,
+    private val timeHighPrecisionMillisProvider: () -> Long = SystemClock::elapsedRealtime,
+) : Clock by Clock.getDefault() {
+    private val baseline = timeSinceEpochMillisProvider() - timeHighPrecisionMillisProvider()
+
+    override fun nanoTime(): Long = baseline + timeHighPrecisionMillisProvider()
+
+    companion object {
+        @JvmStatic
+        val INSTANCE = AndroidClock()
+    }
+}

common/src/test/java/io/opentelemetry/android/common/internal/tools/time/AndroidClockTest.kt

@@ -0,0 +1,48 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.android.common.internal.tools.time
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+
+class AndroidClockTest {
+    @Test
+    fun `nanoTime returns baseline plus elapsed realtime`() {
+        val wallClock = 1000L
+        val elapsedRealtime = 500L
+
+        val clock =
+            AndroidClock(
+                timeSinceEpochMillisProvider = { wallClock },
+                timeHighPrecisionMillisProvider = { elapsedRealtime },
+            )
+
+        val expectedBaseline = wallClock - elapsedRealtime
+        val expectedNanoTime = expectedBaseline + elapsedRealtime
+
+        assertThat(clock.nanoTime()).isEqualTo(expectedNanoTime)
+    }
+
+    @Test
+    fun `nanoTime increases as elapsed realtime increases`() {
+        val wallClock = 1000L
+        var elapsedRealtime = 500L
+
+        val clock =
+            AndroidClock(
+                timeSinceEpochMillisProvider = { wallClock },
+                timeHighPrecisionMillisProvider = { elapsedRealtime },
+            )
+
+        val firstNanoTime = clock.nanoTime()
+        elapsedRealtime = 600L
+        val expectedBaseLine = wallClock - elapsedRealtime
+        val secondNanoTime = clock.nanoTime()
+
+        assertThat(secondNanoTime).isGreaterThan(elapsedRealtime + expectedBaseLine)
+        assertThat(secondNanoTime - firstNanoTime).isEqualTo(100L)
+    }
+}

instrumentation/activity/build.gradle.kts

@@ -11,6 +11,11 @@ android {
     defaultConfig {
         consumerProguardFiles("consumer-rules.pro")
     }
+
+    testOptions {
+        unitTests.isReturnDefaultValues = true
+        unitTests.isIncludeAndroidResources = true
+    }
 }
 
 dependencies {

instrumentation/activity/src/main/java/io/opentelemetry/android/instrumentation/activity/startup/AppStartupTimer.java

@@ -13,10 +13,10 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import io.opentelemetry.android.common.RumConstants;
+import io.opentelemetry.android.common.internal.tools.time.AndroidClock;
 import io.opentelemetry.android.internal.services.visiblescreen.activities.DefaultingActivityLifecycleCallbacks;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.Tracer;
-import io.opentelemetry.sdk.common.Clock;
 import java.util.concurrent.TimeUnit;
 
 public class AppStartupTimer {
@@ -26,7 +26,7 @@ public class AppStartupTimer {
     private static final long MAX_TIME_TO_UI_INIT = TimeUnit.MINUTES.toNanos(1);
 
     // exposed so it can be used for the rest of the startup sequence timing.
-    private final AnchoredClock startupClock = AnchoredClock.create(Clock.getDefault());
+    private final AnchoredClock startupClock = AnchoredClock.create(AndroidClock.getINSTANCE());
     private final long firstPossibleTimestamp = startupClock.now();
     @Nullable private volatile Span overallAppStartSpan = null;
     @Nullable private volatile Runnable completionCallback = null;