From 695483c7ebd0f05a269ce8e194bb33c1515b9635 Mon Sep 17 00:00:00 2001
From: Marcin Oczeretko <marcinoc@google.com>
Date: Tue, 4 Jul 2023 14:56:47 +0000
Subject: [PATCH] Reduce memory churn from main thread looper tracing

Implement getTraceName() on two top Handlers on
the main thread Looper to avoid calls to getClass().getName()

Also avoids posting to main thread handler from the same thread in
FrameTracker callback

Bug: 285737625
Test: Manual - collect a trace and confirm main thread slice names
Change-Id: I7dbbd7702e339e8cf3e7c42d4df3762250e5aca5
---
 core/java/android/view/Choreographer.java     | 11 +++-
 core/java/android/view/ViewRootImpl.java      |  9 ++++
 .../android/internal/jank/FrameTracker.java   | 50 +++++++++----------
 3 files changed, 44 insertions(+), 26 deletions(-)

diff --git a/core/java/android/view/Choreographer.java b/core/java/android/view/Choreographer.java
index d80001def8759..eeb86e99d1b37 100644
--- a/core/java/android/view/Choreographer.java
+++ b/core/java/android/view/Choreographer.java
@@ -34,6 +34,7 @@ import android.os.Message;
 import android.os.SystemClock;
 import android.os.SystemProperties;
 import android.os.Trace;
+import android.os.TraceNameSupplier;
 import android.util.Log;
 import android.util.TimeUtils;
 import android.view.animation.AnimationUtils;
@@ -1300,7 +1301,7 @@ public final class Choreographer {
     }
 
     private final class FrameDisplayEventReceiver extends DisplayEventReceiver
-            implements Runnable {
+            implements Runnable, TraceNameSupplier {
         private boolean mHavePendingVsync;
         private long mTimestampNanos;
         private int mFrame;
@@ -1358,6 +1359,14 @@ public final class Choreographer {
             mHavePendingVsync = false;
             doFrame(mTimestampNanos, mFrame, mLastVsyncEventData);
         }
+
+        @androidx.annotation.NonNull
+        @Override
+        public String getTraceName() {
+            // Returning just a simple name.
+            // More detailed logging happens in onVsync() for TRACE_TAG_VIEW.
+            return "FrameDisplayEventReceiver";
+        }
     }
 
     private static final class CallbackRecord {
diff --git a/core/java/android/view/ViewRootImpl.java b/core/java/android/view/ViewRootImpl.java
index fe25fd20a5b92..6c0059635834b 100644
--- a/core/java/android/view/ViewRootImpl.java
+++ b/core/java/android/view/ViewRootImpl.java
@@ -5787,6 +5787,15 @@ public final class ViewRootImpl implements ViewParent,
     private static final int MSG_PAUSED_FOR_SYNC_TIMEOUT = 37;
 
     final class ViewRootHandler extends Handler {
+        @androidx.annotation.NonNull
+        @Override
+        public String getTraceName(@androidx.annotation.NonNull Message message) {
+            if (message.getCallback() == null) {
+                return getMessageName(message);
+            }
+            return super.getTraceName(message);
+        }
+
         @Override
         public String getMessageName(Message message) {
             switch (message.what) {
diff --git a/core/java/com/android/internal/jank/FrameTracker.java b/core/java/com/android/internal/jank/FrameTracker.java
index 506f19f7719a8..b53be9aceebfd 100644
--- a/core/java/com/android/internal/jank/FrameTracker.java
+++ b/core/java/com/android/internal/jank/FrameTracker.java
@@ -502,35 +502,35 @@ public class FrameTracker extends SurfaceControl.OnJankDataListener
         return vsyncId >= mBeginVsyncId;
     }
 
+    // This will be executed in the HardwareRendererObserver handler, which is the FrameTracker
+    // handler by construction.
     @Override
     public void onFrameMetricsAvailable(int dropCountSinceLastInvocation) {
-        postCallback(() -> {
-            if (mCancelled || mMetricsFinalized) {
-                return;
-            }
+        if (mCancelled || mMetricsFinalized) {
+            return;
+        }
 
-            // Since this callback might come a little bit late after the end() call.
-            // We should keep tracking the begin / end timestamp that we can compare with
-            // vsync timestamp to check if the frame is in the duration of the CUJ.
-            long totalDurationNanos = mMetricsWrapper.getMetric(FrameMetrics.TOTAL_DURATION);
-            boolean isFirstFrame = mMetricsWrapper.getMetric(FrameMetrics.FIRST_DRAW_FRAME) == 1;
-            long frameVsyncId =
-                    mMetricsWrapper.getTiming()[FrameMetrics.Index.FRAME_TIMELINE_VSYNC_ID];
+        // Since this callback might come a little bit late after the end() call.
+        // We should keep tracking the begin / end timestamp that we can compare with
+        // vsync timestamp to check if the frame is in the duration of the CUJ.
+        long totalDurationNanos = mMetricsWrapper.getMetric(FrameMetrics.TOTAL_DURATION);
+        boolean isFirstFrame = mMetricsWrapper.getMetric(FrameMetrics.FIRST_DRAW_FRAME) == 1;
+        long frameVsyncId =
+                mMetricsWrapper.getTiming()[FrameMetrics.Index.FRAME_TIMELINE_VSYNC_ID];
 
-            if (!isInRange(frameVsyncId)) {
-                return;
-            }
-            JankInfo info = findJankInfo(frameVsyncId);
-            if (info != null) {
-                info.hwuiCallbackFired = true;
-                info.totalDurationNanos = totalDurationNanos;
-                info.isFirstFrame = isFirstFrame;
-            } else {
-                mJankInfos.put((int) frameVsyncId, JankInfo.createFromHwuiCallback(
-                        frameVsyncId, totalDurationNanos, isFirstFrame));
-            }
-            processJankInfos();
-        });
+        if (!isInRange(frameVsyncId)) {
+            return;
+        }
+        JankInfo info = findJankInfo(frameVsyncId);
+        if (info != null) {
+            info.hwuiCallbackFired = true;
+            info.totalDurationNanos = totalDurationNanos;
+            info.isFirstFrame = isFirstFrame;
+        } else {
+            mJankInfos.put((int) frameVsyncId, JankInfo.createFromHwuiCallback(
+                    frameVsyncId, totalDurationNanos, isFirstFrame));
+        }
+        processJankInfos();
     }
 
     @UiThread