commit b8f2a2d5ada9bed7e430b3a5f64fa79e376ab905
author Vishnu Nair <vishnun@google.com> Thu Jan 13 08:10:10 2022 -0800
committer Vishnu Nair <vishnun@google.com> Wed Jan 19 16:58:02 2022 -0800
tree afb8d4133e92a51aefa561d7f4dcfe8a85fcb4be
parent 858a3b4c8dfa03a5952cad4b0b695ee2cb4c31e8

SF: Only create a starting entry if there are starting states

Test: atest TransactionTracingTest
Bug: 200284593
Change-Id: Ie260fb094117ec754778f8277602d10df6606fb2

services/surfaceflinger/Tracing/TransactionTracing.cpp

diff --git a/services/surfaceflinger/Tracing/TransactionTracing.cpp b/services/surfaceflinger/Tracing/TransactionTracing.cpp
index 5136295..a46b795 100644
--- a/services/surfaceflinger/Tracing/TransactionTracing.cpp
+++ b/services/surfaceflinger/Tracing/TransactionTracing.cpp
@@ -128,7 +128,9 @@
             mCommittedTransactions.clear();
         } // unlock mMainThreadLock
 
-        addEntry(committedTransactions, removedLayers);
+        if (!committedTransactions.empty() || !removedLayers.empty()) {
+            addEntry(committedTransactions, removedLayers);
+        }
     }
 }
 
@@ -275,6 +277,7 @@
 
 void TransactionTracing::updateStartingStateLocked(
         const proto::TransactionTraceEntry& removedEntry) {
+    mStartingTimestamp = removedEntry.elapsed_realtime_nanos();
     // Keep track of layer starting state so we can reconstruct the layer state as we purge
     // transactions from the buffer.
     for (const proto::LayerCreationArgs& addedLayer : removedEntry.added_layers()) {
@@ -303,13 +306,14 @@
 }
 
 void TransactionTracing::addStartingStateToProtoLocked(proto::TransactionTraceFile& proto) {
-    proto::TransactionTraceEntry* entryProto = proto.add_entry();
-    entryProto->set_elapsed_realtime_nanos(mStartingTimestamp);
-    entryProto->set_vsync_id(0);
     if (mStartingStates.size() == 0) {
         return;
     }
 
+    proto::TransactionTraceEntry* entryProto = proto.add_entry();
+    entryProto->set_elapsed_realtime_nanos(mStartingTimestamp);
+    entryProto->set_vsync_id(0);
+
     entryProto->mutable_added_layers()->Reserve(static_cast<int32_t>(mStartingStates.size()));
     for (auto& [layerId, state] : mStartingStates) {
         entryProto->mutable_added_layers()->Add(TransactionProtoParser::toProto(state.args));