Allow ComponentsLogger implementations to return null for event types they don't care about

Summary: Quality of life improvement for when people implement loggers that don't care about certain events.

Reviewed By: gmoeck

Differential Revision: D15915909

fbshipit-source-id: ce500e3a75f5412aea9a1ea7808c2635cd919a85

Author: astreet

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

@@ -33,7 +33,11 @@ enum LogLevel {
     FATAL
   }
 
-  /** Create a new performance event with the given event id and start counting the time. */
+  /**
+   * Create a new performance event with the given event id and start counting the time. If the
+   * logger doesn't care about this event id, it may return null.
+   */
+  @Nullable
   PerfEvent newPerformanceEvent(ComponentContext c, @FrameworkLogEvents.LogEventId int eventId);
 
   /** Write a {@link PerfEvent} to storage. This also marks the end of the event. */

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

@@ -37,7 +37,11 @@ private LogTreePopulator() {}
   @Nullable
   @CheckReturnValue
   public static PerfEvent populatePerfEventFromLogger(
-      ComponentContext c, ComponentsLogger logger, PerfEvent perfEvent) {
+      ComponentContext c, ComponentsLogger logger, @Nullable PerfEvent perfEvent) {
+    if (perfEvent == null) {
+      return null;
+    }
+
     final String logTag = c.getLogTag();
     if (logTag == null) {
       logger.cancelPerfEvent(perfEvent);

litho-it/src/test/java/com/facebook/litho/LayoutStateCalculateTest.java

@@ -59,6 +59,7 @@
 import android.graphics.Rect;
 import android.util.SparseArray;
 import android.view.accessibility.AccessibilityManager;
+import androidx.annotation.Nullable;
 import com.facebook.litho.config.ComponentsConfiguration;
 import com.facebook.litho.testing.TestComponent;
 import com.facebook.litho.testing.TestDrawableComponent;
@@ -67,6 +68,7 @@
 import com.facebook.litho.testing.TestSizeDependentComponent;
 import com.facebook.litho.testing.TestViewComponent;
 import com.facebook.litho.testing.Whitebox;
+import com.facebook.litho.testing.logging.TestComponentsLogger;
 import com.facebook.litho.testing.testrunner.ComponentsTestRunner;
 import com.facebook.litho.testing.util.InlineLayoutSpec;
 import com.facebook.litho.widget.Text;
@@ -2765,6 +2767,36 @@ protected Component onCreateLayout(final ComponentContext c) {
     ComponentsConfiguration.createPhantomLayoutOutputsForTransitions = false;
   }
 
+  @Test
+  public void testComponentsLoggerCanReturnNullPerfEventsDuringLayout() {
+    final Component component =
+        new InlineLayoutSpec() {
+          @Override
+          protected Component onCreateLayout(final ComponentContext c) {
+            return create(c).child(TestDrawableComponent.create(c)).wrapInView().build();
+          }
+        };
+
+    final ComponentsLogger logger =
+        new TestComponentsLogger() {
+          @Override
+          public @Nullable PerfEvent newPerformanceEvent(ComponentContext c, int eventId) {
+            return null;
+          }
+        };
+
+    final LayoutState layoutState =
+        LayoutState.calculate(
+            new ComponentContext(application, "test", logger),
+            component,
+            -1,
+            makeSizeSpec(100, EXACTLY),
+            makeSizeSpec(100, EXACTLY),
+            LayoutState.CalculateLayoutSource.TEST);
+
+    assertThat(layoutState.getMountableOutputCount()).isEqualTo(2);
+  }
+
   private void enableAccessibility() {
     final ShadowAccessibilityManager manager = Shadows.shadowOf(
         (AccessibilityManager)

litho-it/src/test/java/com/facebook/litho/LogTreePopulatorTest.java

@@ -150,5 +150,19 @@ public Map<String, String> getExtraAnnotations(TreeProps treeProps) {
     assertThat(res).isEqualTo("my_key:1337:other_key:value:");
   }
 
+  @Test
+  public void testSkipNullPerfEvent() {
+    final ComponentsLogger logger =
+        new TestComponentsLogger() {
+          @Nullable
+          @Override
+          public Map<String, String> getExtraAnnotations(TreeProps treeProps) {
+            return null;
+          }
+        };
+
+    assertThat(LogTreePopulator.populatePerfEventFromLogger(mContext, logger, null)).isNull();
+  }
+
   private static class MyKey {}
 }