commit 7459e82259b91dee3b18e3188d75c304db720e97
author Peter Kalauskas <peskal@google.com> Tue Apr 23 06:53:43 2024 -0700
committer Peter Kalauskas <peskal@google.com> Tue Apr 23 07:19:43 2024 -0700
tree e63d10379e35a0177e0f92c8cfcf08a394230be1
parent d739277b011db6f9f5cedede0a145a4ea55983aa

Trace coroutine section name generation

To assess whether coroutine tracing is slow due to context switching,
or if it is slow due to stack unwinding to generate default sections
names, create a new trace section so it can be measured.

Flag: ACONFIG com.android.systemui.coroutine_tracing DISABLED
Bug: 289353932
Test: capture and inspect perfetto trace
Change-Id: I77dcdab40574f1e339c570f6d9984a1bc6aa0644

packages/SystemUI/src/com/android/systemui/lifecycle/RepeatWhenAttached.kt

diff --git a/packages/SystemUI/src/com/android/systemui/lifecycle/RepeatWhenAttached.kt b/packages/SystemUI/src/com/android/systemui/lifecycle/RepeatWhenAttached.kt
index 5dafd94..c997617 100644
--- a/packages/SystemUI/src/com/android/systemui/lifecycle/RepeatWhenAttached.kt
+++ b/packages/SystemUI/src/com/android/systemui/lifecycle/RepeatWhenAttached.kt
@@ -17,6 +17,7 @@
 
 package com.android.systemui.lifecycle
 
+import android.os.Trace
 import android.view.View
 import android.view.ViewTreeObserver
 import androidx.annotation.MainThread
@@ -73,7 +74,7 @@
         Dispatchers.Main + createCoroutineTracingContext() + coroutineContext
     val traceName =
         if (Compile.IS_DEBUG && coroutineTracing()) {
-            traceSectionName()
+            inferTraceSectionName()
         } else {
             DEFAULT_TRACE_NAME
         }
@@ -197,16 +198,21 @@
     frame.className != CURRENT_CLASS_NAME && frame.className != JAVA_ADAPTER_CLASS_NAME
 
 /** Get a name for the trace section include the name of the call site. */
-private fun traceSectionName(): String {
-    val interestingFrame =
-        StackWalker.getInstance().walk { stream ->
-            stream.filter(::isFrameInteresting).limit(5).findFirst()
+private fun inferTraceSectionName(): String {
+    try {
+        Trace.traceBegin(Trace.TRACE_TAG_APP, "RepeatWhenAttachedKt#inferTraceSectionName")
+        val interestingFrame =
+            StackWalker.getInstance().walk { stream ->
+                stream.filter(::isFrameInteresting).limit(5).findFirst()
+            }
+        if (interestingFrame.isPresent) {
+            val f = interestingFrame.get()
+            return "${f.className}#${f.methodName}:${f.lineNumber} [$DEFAULT_TRACE_NAME]"
+        } else {
+            return DEFAULT_TRACE_NAME
         }
-    if (interestingFrame.isPresent) {
-        val frame = interestingFrame.get()
-        return "${frame.className}#${frame.methodName}:${frame.lineNumber} [$DEFAULT_TRACE_NAME]"
-    } else {
-        return DEFAULT_TRACE_NAME
+    } finally {
+        Trace.traceEnd(Trace.TRACE_TAG_APP)
     }
 }