Add events for RenderTreeMountStart and RenderTreeMountEnd.

Summary: This will enable us to see all mount related events happening between the start and end of a render Tree mount.

Reviewed By: LukeDefeo

Differential Revision: D51805336

fbshipit-source-id: f4e676d171eace7fa61ca08b032bb287653ddce1

Author: Fabio Carballo

litho-core/src/main/java/com/facebook/litho/BaseMountingView.java

@@ -97,6 +97,7 @@ public BaseMountingView(ComponentContext context, @Nullable AttributeSet attrs)
     mMountState.setEnsureParentMounted(true);
     mViewAttributeFlags = LithoMountData.getViewAttributeFlags(this);
   }
+
   /**
    * Sets the width that the BaseMountingView should take on the next measure pass and then requests
    * a layout. This should be called from animation-driving code on each frame to animate the size

litho-rendercore/src/main/java/com/facebook/rendercore/MountState.java

@@ -20,6 +20,7 @@
 import static com.facebook.rendercore.debug.DebugEventAttribute.Description;
 import static com.facebook.rendercore.debug.DebugEventAttribute.HashCode;
 import static com.facebook.rendercore.debug.DebugEventAttribute.Key;
+import static com.facebook.rendercore.debug.DebugEventAttribute.NumMountableOutputs;
 import static com.facebook.rendercore.debug.DebugEventAttribute.RenderUnitId;
 import static com.facebook.rendercore.debug.DebugEventAttribute.RootHostHashCode;
 import static com.facebook.rendercore.debug.DebugEventDispatcher.beginTrace;
@@ -34,6 +35,7 @@
 import androidx.collection.LongSparseArray;
 import androidx.core.util.Preconditions;
 import com.facebook.rendercore.debug.DebugEvent;
+import com.facebook.rendercore.debug.DebugEventDispatcher;
 import com.facebook.rendercore.extensions.ExtensionState;
 import com.facebook.rendercore.extensions.MountExtension;
 import com.facebook.rendercore.extensions.RenderCoreExtension;
@@ -43,6 +45,7 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
+import kotlin.Unit;
 
 public class MountState implements MountDelegateTarget {
 
@@ -127,13 +130,24 @@ public void mount(RenderTree renderTree) {
     if (traceIdentifier != null) {
       HashMap<String, Object> attributes = new HashMap<>();
       attributes.put(RootHostHashCode, mRootHost.hashCode());
+      attributes.put(NumMountableOutputs, renderTree.getMountableOutputCount());
 
       beginTrace(
           traceIdentifier,
           DebugEvent.RenderTreeMounted,
           String.valueOf(renderTree.getRenderStateId()),
           attributes);
     }
+
+    DebugEventDispatcher.dispatch(
+        DebugEvent.RenderTreeMountStart,
+        () -> String.valueOf(renderTree.getRenderStateId()),
+        attrs -> {
+          attrs.put(RootHostHashCode, mRootHost.hashCode());
+          attrs.put(NumMountableOutputs, renderTree.getMountableOutputCount());
+          return Unit.INSTANCE;
+        });
+
     try {
 
       if (mIsMounting) {
@@ -229,6 +243,15 @@ public void mount(RenderTree renderTree) {
         endTrace(traceIdentifier);
       }
       mIsMounting = false;
+
+      DebugEventDispatcher.dispatch(
+          DebugEvent.RenderTreeMountEnd,
+          () -> String.valueOf(renderTree.getRenderStateId()),
+          attrs -> {
+            attrs.put(RootHostHashCode, mRootHost.hashCode());
+            attrs.put(NumMountableOutputs, renderTree.getMountableOutputCount());
+            return Unit.INSTANCE;
+          });
     }
   }
 

litho-rendercore/src/main/java/com/facebook/rendercore/debug/DebugEvents.kt

@@ -45,6 +45,8 @@ sealed class DebugEvent(
     const val ViewOnLayout = "RenderCore.View.OnLayout"
     const val IncrementalMountStart = "RenderCore.IncrementalMount.Start"
     const val IncrementalMountEnd = "RenderCore.IncrementalMount.End"
+    const val RenderTreeMountStart = "RenderCore.RenderTreeMount.Start"
+    const val RenderTreeMountEnd = "RenderCore.RenderTreeMount.End"
   }
 
   /** Returns the value of attribute with [name]. */
@@ -97,6 +99,7 @@ object DebugEventAttribute {
   const val Key = "key"
   const val VisibleRect = "visibleRect"
   const val BoundsVisible = "areBoundsVisible"
+  const val NumMountableOutputs = "numMountableOutputs"
 }
 
 /** Base class for marker events */