Cancel dropped log events

Summary:
APIs may require that events are properly released instead of just dropped.
I recently added some restrictions to when MOUNT events, in particular, are
logged and this led to a bunch of events never getting properly canceled/released.

This adds the necessary interface to the ComponentsLogger and implements it
where necessary.

Reviewed By: IanChilds

Differential Revision: D9447798

fbshipit-source-id: 106191d9aabf0ccc8db098ae8edc93e3386d795a

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

@@ -39,6 +39,9 @@ enum LogLevel {
   /** Write a {@link PerfEvent} to storage. This also marks the end of the event. */
   void logPerfEvent(PerfEvent event);
 
+  /** Release a previously obtained {@link PerfEvent} without logging it. */
+  void cancelPerfEvent(PerfEvent event);
+
   /**
    * Emit a message that can be logged or escalated by the logger implementation.
    *

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

@@ -40,6 +40,7 @@ public static PerfEvent populatePerfEventFromLogger(
       ComponentContext c, ComponentsLogger logger, PerfEvent perfEvent) {
     final String logTag = c.getLogTag();
     if (logTag == null) {
+      logger.cancelPerfEvent(perfEvent);
       return null;
     }
 

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

@@ -386,22 +386,25 @@ && canMountIncrementally(component)) {
 
     suppressInvalidationsOnHosts(false);
 
-    logMountPerfEvent(componentTree, logger, mountPerfEvent);
+    if (logger != null) {
+      logMountPerfEvent(logger, mountPerfEvent);
+    }
 
     if (isTracing) {
       ComponentsSystrace.endSection();
     }
   }
 
-  private void logMountPerfEvent(
-      ComponentTree componentTree, ComponentsLogger logger, @Nullable PerfEvent mountPerfEvent) {
+  private void logMountPerfEvent(ComponentsLogger logger, @Nullable PerfEvent mountPerfEvent) {
     if (!mMountStats.isLoggingEnabled || mountPerfEvent == null) {
+      logger.cancelPerfEvent(mountPerfEvent);
       return;
     }
 
     // MOUNT events that don't mount any content are not valuable enough to log at the moment.
     // We will likely enable them again in the future. T31729233
     if (mMountStats.mountedCount == 0) {
+      logger.cancelPerfEvent(mountPerfEvent);
       return;
     }
 

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

@@ -71,7 +71,7 @@ public Map<String, String> getExtraAnnotations(TreeProps treeProps) {
 
   @Test
   public void testSkipOnEmptyTag() {
-    final BaseComponentsLogger logger =
+    final TestComponentsLogger logger =
         new TestComponentsLogger() {
           @Nullable
           @Override
@@ -91,7 +91,11 @@ public Map<String, String> getExtraAnnotations(TreeProps treeProps) {
     mContext.setTreeProps(treeProps);
 
     final ComponentContext noLogTagContext = new ComponentContext(RuntimeEnvironment.application);
-    LogTreePopulator.populatePerfEventFromLogger(noLogTagContext, logger, event);
+    final PerfEvent perfEvent =
+        LogTreePopulator.populatePerfEventFromLogger(noLogTagContext, logger, event);
+
+    assertThat(perfEvent).isNull();
+    assertThat(logger.getCanceledPerfEvents()).containsExactly(event);
 
     verifyNoMoreInteractions(event);
   }

litho-testing/src/main/java/com/facebook/litho/testing/logging/TestComponentsLogger.java

@@ -31,6 +31,7 @@
 public class TestComponentsLogger extends BaseComponentsLogger {
 
   private final List<PerfEvent> mLoggedPerfEvents = new LinkedList<>();
+  private final List<PerfEvent> mCanceledPerfEvents = new LinkedList<>();
   private final List<Pair<LogLevel, String>> mLoggedMessages = new LinkedList<>();
 
   @Override
@@ -43,6 +44,11 @@ public PerfEvent newPerformanceEvent(@FrameworkLogEvents.LogEventId int eventId)
     return new TestPerfEvent(eventId);
   }
 
+  @Override
+  public void cancelPerfEvent(PerfEvent event) {
+    mCanceledPerfEvents.add(event);
+  }
+
   @Override
   public void logPerfEvent(PerfEvent event) {
     mLoggedPerfEvents.add(event);
@@ -62,6 +68,10 @@ public List<PerfEvent> getLoggedPerfEvents() {
     return mLoggedPerfEvents;
   }
 
+  public List<PerfEvent> getCanceledPerfEvents() {
+    return mCanceledPerfEvents;
+  }
+
   public List<Pair<LogLevel, String>> getLoggedMessages() {
     return mLoggedMessages;
   }

sample-kotlin/src/main/java/com/fblitho/lithoktsample/logging/SampleComponentsLogger.kt

@@ -31,6 +31,10 @@ class SampleComponentsLogger : BaseComponentsLogger() {
         printEventData(event, PerfEventStore.release(event))
     }
 
+    override fun cancelPerfEvent(event: PerfEvent) {
+        PerfEventStore.release(event)
+    }
+
     override fun emitMessage(level: ComponentsLogger.LogLevel, message: String) {
         when (level) {
             ComponentsLogger.LogLevel.WARNING -> {