feat(instrumentation): Add FirstDraw spans to activity instrumentation

common/api/common.api

@@ -7,6 +7,8 @@ public final class io/opentelemetry/android/common/RumConstants {
 	public static final field OTEL_RUM_LOG_TAG Ljava/lang/String;
 	public static final field RUM_SDK_VERSION Lio/opentelemetry/api/common/AttributeKey;
 	public static final field SCREEN_NAME_KEY Lio/opentelemetry/api/common/AttributeKey;
+	public static final field SCREEN_VIEW_DEPTH_KEY Lio/opentelemetry/api/common/AttributeKey;
+	public static final field SCREEN_VIEW_NODES_KEY Lio/opentelemetry/api/common/AttributeKey;
 	public static final field START_TYPE_KEY Lio/opentelemetry/api/common/AttributeKey;
 	public static final field STORAGE_SPACE_FREE_KEY Lio/opentelemetry/api/common/AttributeKey;
 }

common/src/main/java/io/opentelemetry/android/common/RumConstants.kt

@@ -31,6 +31,12 @@ object RumConstants {
     @JvmField
     val BATTERY_PERCENT_KEY: AttributeKey<Double> = AttributeKey.doubleKey("battery.percent")
 
+    @JvmField
+    val SCREEN_VIEW_NODES_KEY: AttributeKey<Long> = AttributeKey.longKey("screen.view.nodes")
+
+    @JvmField
+    val SCREEN_VIEW_DEPTH_KEY: AttributeKey<Long> = AttributeKey.longKey("screen.view.depth")
+
     const val APP_START_SPAN_NAME: String = "AppStart"
 
     object Events {

instrumentation/activity/README.md

@@ -38,6 +38,20 @@ This instrumentation produces the following telemetry:
   * `screen.name`:  name of screen
   * `last.screen.name`:  name of screen, only when span contains the `activityPostResumed` event.
 
+### First Draw
+
+* Type: Span
+* Name: `FirstDraw`
+* Description: On activity PreCreated or Created (pre API 29) callback, a span will be created
+  to represent the time that the UI pipeline took to render that Activity's first frame. The span ends
+  at the first draw of the window
+  [DecorView](https://developer.android.com/reference/android/view/Window#getDecorView())
+* Attributes:
+  * `activity.name`:  name of activity
+  * `screen.name`:  name of screen
+  * `screen.view.nodes`: a recursive count of all View nodes under the window DecorView. This gives a measure of the amount of work being done in the *layout-and-measure* stage of the UI pipeline. A high count correlates with longer FirstDraw. System-defined layers are included in this count.
+  * `screen.view.depth`: the depth of the deepest-nested View under the window DecorView. This gives a measure of your UI complexity; more work must be done for a deeply-nested View heirarchy. A high count correlates with longer FirstDraw. System-defined layers (usually 4-6) are included when calculating the depth.
+
 ## Installation
 
 This instrumentation comes with the [android agent](../../android-agent) out of the box, so

instrumentation/activity/api/activity.api

@@ -38,6 +38,7 @@ public class io/opentelemetry/android/instrumentation/activity/ActivityTracer {
 public class io/opentelemetry/android/instrumentation/activity/ActivityTracerCache {
 	public fun <init> (Lio/opentelemetry/api/trace/Tracer;Lio/opentelemetry/android/internal/services/visiblescreen/VisibleScreenTracker;Lio/opentelemetry/android/instrumentation/activity/startup/AppStartupTimer;Lio/opentelemetry/android/instrumentation/common/ScreenNameExtractor;)V
 	public fun addEvent (Landroid/app/Activity;Ljava/lang/String;)Lio/opentelemetry/android/instrumentation/activity/ActivityTracer;
+	public fun endInitialDrawSpan (Landroid/app/Activity;)V
 	public fun initiateRestartSpanIfNecessary (Landroid/app/Activity;)Lio/opentelemetry/android/instrumentation/activity/ActivityTracer;
 	public fun startActivityCreation (Landroid/app/Activity;)Lio/opentelemetry/android/instrumentation/activity/ActivityTracer;
 	public fun startSpanIfNoneInProgress (Landroid/app/Activity;Ljava/lang/String;)Lio/opentelemetry/android/instrumentation/activity/ActivityTracer;

instrumentation/activity/src/main/java/io/opentelemetry/android/instrumentation/activity/ActivityCallbacks.kt

@@ -7,6 +7,7 @@ package io.opentelemetry.android.instrumentation.activity
 
 import android.app.Activity
 import android.os.Bundle
+import io.opentelemetry.android.instrumentation.activity.draw.FirstDrawListener
 import io.opentelemetry.android.internal.services.visiblescreen.activities.DefaultingActivityLifecycleCallbacks
 
 class ActivityCallbacks(
@@ -17,6 +18,9 @@ class ActivityCallbacks(
         savedInstanceState: Bundle?,
     ) {
         tracers.startActivityCreation(activity).addEvent("activityPreCreated")
+        FirstDrawListener.registerFirstDraw(activity) {
+            tracers.endInitialDrawSpan(activity)
+        }
     }
 
     override fun onActivityCreated(

instrumentation/activity/src/main/java/io/opentelemetry/android/instrumentation/activity/ActivityTracer.java

@@ -31,6 +31,7 @@ public class ActivityTracer {
     private final String screenName;
     private final AppStartupTimer appStartupTimer;
     private final ActiveSpan activeSpan;
+    @Nullable private Span initialDrawSpan;
 
     private ActivityTracer(Builder builder) {
         this.initialAppActivity = builder.initialAppActivity;
@@ -50,7 +51,9 @@ ActivityTracer startSpanIfNoneInProgress(String spanName) {
     }
 
     ActivityTracer startActivityCreation() {
-        activeSpan.startSpan(this::makeCreationSpan);
+        Span creationSpan = makeCreationSpan();
+        activeSpan.startSpan(() -> creationSpan);
+        startInitialDrawSpan(creationSpan);
         return this;
     }
 
@@ -135,6 +138,19 @@ public ActivityTracer addEvent(String eventName) {
         return this;
     }
 
+    void startInitialDrawSpan(Span parentSpan) {
+        if (initialDrawSpan == null) {
+            initialDrawSpan = createSpanWithParent("FirstDraw", parentSpan);
+        }
+    }
+
+    void endInitialDrawSpan() {
+        if (initialDrawSpan != null) {
+            initialDrawSpan.end();
+            initialDrawSpan = null;
+        }
+    }
+
     static Builder builder(Activity activity) {
         return new Builder(activity);
     }

instrumentation/activity/src/main/java/io/opentelemetry/android/instrumentation/activity/ActivityTracerCache.java

@@ -79,6 +79,10 @@ public ActivityTracer startActivityCreation(Activity activity) {
         return getTracer(activity).startActivityCreation();
     }
 
+    public void endInitialDrawSpan(Activity activity) {
+        getTracer(activity).endInitialDrawSpan();
+    }
+
     private ActivityTracer getTracer(Activity activity) {
         ActivityTracer activityTracer =
                 tracersByActivityClassName.get(activity.getClass().getName());

instrumentation/activity/src/main/java/io/opentelemetry/android/instrumentation/activity/Pre29ActivityCallbacks.java

@@ -9,6 +9,7 @@
 import android.os.Bundle;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import io.opentelemetry.android.instrumentation.activity.draw.FirstDrawListener;
 import io.opentelemetry.android.internal.services.visiblescreen.activities.DefaultingActivityLifecycleCallbacks;
 
 public class Pre29ActivityCallbacks implements DefaultingActivityLifecycleCallbacks {
@@ -21,6 +22,12 @@ public Pre29ActivityCallbacks(ActivityTracerCache tracers) {
     @Override
     public void onActivityCreated(@NonNull Activity activity, @Nullable Bundle savedInstanceState) {
         tracers.startActivityCreation(activity).addEvent("activityCreated");
+        FirstDrawListener.INSTANCE.registerFirstDraw(
+                activity,
+                () -> {
+                    tracers.endInitialDrawSpan(activity);
+                    return null;
+                });
     }
 
     @Override

instrumentation/activity/src/main/java/io/opentelemetry/android/instrumentation/activity/draw/FirstDrawListener.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.android.instrumentation.activity.draw
+
+import android.app.Activity
+import android.os.Build
+import android.os.Handler
+import android.os.Looper
+import android.view.View
+import android.view.ViewTreeObserver
+
+internal object FirstDrawListener {
+    fun registerFirstDraw(
+        activity: Activity,
+        drawDoneCallback: () -> Unit,
+    ) {
+        val window = activity.window
+
+        // Wait until the decorView is created until we actually use it
+        window.onDecorViewReady {
+            val decorView = window.peekDecorView()
+            val versionsBeforeBugFix = Build.VERSION.SDK_INT < Build.VERSION_CODES.O
+            val decorViewAttached = decorView.viewTreeObserver.isAlive && decorView.isAttachedToWindow
+
+            // Before API version 26, draw listeners were not merged back into the real view tree observer
+            // Workaround is to wait until the view is attached before registering draw listeners
+            // Source: https://android.googlesource.com/platform/frameworks/base/+/9f8ec54244a5e0343b9748db3329733f259604f3
+            if (versionsBeforeBugFix && !decorViewAttached) {
+                decorView.addOnAttachStateChangeListener(
+                    object : View.OnAttachStateChangeListener {
+                        override fun onViewAttachedToWindow(v: View) {
+                            decorView.viewTreeObserver.addOnDrawListener(NextDrawListener(decorView, drawDoneCallback))
+                            decorView.removeOnAttachStateChangeListener(this)
+                        }
+
+                        override fun onViewDetachedFromWindow(v: View) = Unit
+                    },
+                )
+            } else {
+                decorView.viewTreeObserver.addOnDrawListener(NextDrawListener(decorView, drawDoneCallback))
+            }
+        }
+    }
+
+    /**
+     * ViewTreeObserver.removeOnDrawListener() cannot be called from the onDraw() callback,
+     * so remove it in next draw.
+     */
+    internal class NextDrawListener(
+        val view: View,
+        val drawDoneCallback: () -> Unit,
+        val handler: Handler = Handler(Looper.getMainLooper()),
+    ) : ViewTreeObserver.OnDrawListener {
+        var invoked = false
+
+        override fun onDraw() {
+            if (!invoked) {
+                invoked = true
+                drawDoneCallback()
+                handler.post {
+                    if (view.viewTreeObserver.isAlive) {
+                        view.viewTreeObserver.removeOnDrawListener(this)
+                    }
+                }
+            }
+        }
+    }
+}

instrumentation/activity/src/main/java/io/opentelemetry/android/instrumentation/activity/draw/WindowUtils.kt

@@ -0,0 +1,58 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.android.instrumentation.activity.draw
+
+import android.os.Build
+import android.view.ActionMode
+import android.view.SearchEvent
+import android.view.Window
+import androidx.annotation.RequiresApi
+
+internal fun Window.onDecorViewReady(callback: () -> Unit) {
+    if (peekDecorView() == null) {
+        onContentChanged {
+            callback()
+            return@onContentChanged false
+        }
+    } else {
+        callback()
+    }
+}
+
+internal fun Window.onContentChanged(callbackInvocation: () -> Boolean) {
+    val currentCallback = callback
+    val callback =
+        if (currentCallback is WindowDelegateCallback) {
+            currentCallback
+        } else {
+            val newCallback = WindowDelegateCallback(currentCallback)
+            callback = newCallback
+            newCallback
+        }
+    callback.onContentChangedCallbacks += callbackInvocation
+}
+
+internal class WindowDelegateCallback(
+    private val delegate: Window.Callback,
+) : Window.Callback by delegate {
+    val onContentChangedCallbacks = mutableListOf<() -> Boolean>()
+
+    override fun onContentChanged() {
+        onContentChangedCallbacks.removeAll { callback ->
+            !callback()
+        }
+        delegate.onContentChanged()
+    }
+
+    @RequiresApi(Build.VERSION_CODES.M)
+    override fun onSearchRequested(searchEvent: SearchEvent): Boolean = delegate.onSearchRequested(searchEvent)
+
+    @RequiresApi(Build.VERSION_CODES.M)
+    override fun onWindowStartingActionMode(
+        callback: ActionMode.Callback,
+        type: Int,
+    ): ActionMode? = delegate.onWindowStartingActionMode(callback, type)
+}

instrumentation/activity/src/test/java/io/opentelemetry/android/instrumentation/activity/ActivityCallbacksTest.kt

@@ -8,7 +8,9 @@ package io.opentelemetry.android.instrumentation.activity
 import android.app.Activity
 import io.mockk.every
 import io.mockk.mockk
+import io.mockk.mockkObject
 import io.opentelemetry.android.common.RumConstants
+import io.opentelemetry.android.instrumentation.activity.draw.FirstDrawListener
 import io.opentelemetry.android.instrumentation.activity.startup.AppStartupTimer
 import io.opentelemetry.android.instrumentation.common.ScreenNameExtractor
 import io.opentelemetry.android.internal.services.visiblescreen.VisibleScreenTracker
@@ -40,6 +42,9 @@ internal class ActivityCallbacksTest {
         val extractor = mockk<ScreenNameExtractor>(relaxed = true)
         every { extractor.extract(any<Activity>()) } returns "Activity"
         tracers = ActivityTracerCache(tracer, visibleScreenTracker, startupTimer, extractor)
+
+        mockkObject(FirstDrawListener)
+        every { FirstDrawListener.registerFirstDraw(any(), any()) } returns Unit
     }
 
     @Test

instrumentation/activity/src/test/java/io/opentelemetry/android/instrumentation/activity/ActivityTracerCacheTest.kt

@@ -141,4 +141,14 @@ internal class ActivityTracerCacheTest {
         assertSame(activityTracer, result)
         Mockito.verify(activityTracer).startActivityCreation()
     }
+
+    @Test
+    fun endInitialDrawSpan() {
+        Mockito.`when`(tracerCreator.apply(activity)).thenReturn(activityTracer)
+
+        val underTest = ActivityTracerCache(tracerCreator)
+
+        underTest.endInitialDrawSpan(activity)
+        Mockito.verify(activityTracer).endInitialDrawSpan()
+    }
 }

instrumentation/activity/src/test/java/io/opentelemetry/android/instrumentation/activity/Pre29ActivityLifecycleCallbacksTest.kt

@@ -8,7 +8,9 @@ package io.opentelemetry.android.instrumentation.activity
 import android.app.Activity
 import io.mockk.every
 import io.mockk.mockk
+import io.mockk.mockkObject
 import io.opentelemetry.android.common.RumConstants
+import io.opentelemetry.android.instrumentation.activity.draw.FirstDrawListener
 import io.opentelemetry.android.instrumentation.activity.startup.AppStartupTimer
 import io.opentelemetry.android.instrumentation.common.ScreenNameExtractor
 import io.opentelemetry.android.internal.services.visiblescreen.VisibleScreenTracker
@@ -39,6 +41,9 @@ internal class Pre29ActivityLifecycleCallbacksTest {
         val extractor = mockk<ScreenNameExtractor>(relaxed = true)
         every { extractor.extract(any<Activity>()) } returns "Activity"
         tracers = ActivityTracerCache(tracer, visibleScreenTracker, appStartupTimer, extractor)
+
+        mockkObject(FirstDrawListener)
+        every { FirstDrawListener.registerFirstDraw(any(), any()) } returns Unit
     }
 
     @Test