Merge "Avoid capturing always on tracing when generating layers trace" into main
diff --git a/services/surfaceflinger/Tracing/TransactionTracing.h b/services/surfaceflinger/Tracing/TransactionTracing.h
index ddbf3e4..6a66fff 100644
--- a/services/surfaceflinger/Tracing/TransactionTracing.h
+++ b/services/surfaceflinger/Tracing/TransactionTracing.h
@@ -218,6 +218,13 @@
     friend class Singleton<TransactionTracing>;
     std::function<void(const std::string& prefix, bool overwrite)> mWriterFunction =
             [](const std::string&, bool) {};
+    std::atomic<bool> mEnabled{true};
+
+    void doInvoke(const std::string& filename, bool overwrite) {
+        if (mEnabled) {
+            mWriterFunction(filename, overwrite);
+        }
+    };
 
 public:
     void setWriterFunction(
@@ -225,12 +232,15 @@
         mWriterFunction = std::move(function);
     }
     void invoke(const std::string& prefix, bool overwrite) {
-        mWriterFunction(TransactionTracing::getFilePath(prefix), overwrite);
+        doInvoke(TransactionTracing::getFilePath(prefix), overwrite);
     }
     /* pass in a complete file path for testing */
     void invokeForTest(const std::string& filename, bool overwrite) {
-        mWriterFunction(filename, overwrite);
+        doInvoke(filename, overwrite);
     }
+    /* hacky way to avoid generating traces when converting transaction trace to layers trace. */
+    void disable() { mEnabled.store(false); }
+    void enable() { mEnabled.store(true); }
 };
 
 } // namespace android
diff --git a/services/surfaceflinger/Tracing/tools/LayerTraceGenerator.cpp b/services/surfaceflinger/Tracing/tools/LayerTraceGenerator.cpp
index 3f46e6c..617ea2c 100644
--- a/services/surfaceflinger/Tracing/tools/LayerTraceGenerator.cpp
+++ b/services/surfaceflinger/Tracing/tools/LayerTraceGenerator.cpp
@@ -40,9 +40,24 @@
 namespace android {
 using namespace ftl::flag_operators;
 
+namespace {
+class ScopedTraceDisabler {
+public:
+    ScopedTraceDisabler() { TransactionTraceWriter::getInstance().disable(); }
+    ~ScopedTraceDisabler() { TransactionTraceWriter::getInstance().enable(); }
+};
+} // namespace
+
 bool LayerTraceGenerator::generate(const perfetto::protos::TransactionTraceFile& traceFile,
                                    std::uint32_t traceFlags, LayerTracing& layerTracing,
                                    bool onlyLastEntry) {
+    // We are generating the layers trace by replaying back a set of transactions. If the
+    // transactions have unexpected states, we may generate a transaction trace to debug
+    // the unexpected state. This is silly. So we disable it by poking the
+    // TransactionTraceWriter. This is really a hack since we should manage our depenecies a
+    // little better.
+    ScopedTraceDisabler fatalErrorTraceDisabler;
+
     if (traceFile.entry_size() == 0) {
         ALOGD("Trace file is empty");
         return false;
diff --git a/services/surfaceflinger/tests/unittests/TransactionTraceWriterTest.cpp b/services/surfaceflinger/tests/unittests/TransactionTraceWriterTest.cpp
index 4a83d44..d071ce9 100644
--- a/services/surfaceflinger/tests/unittests/TransactionTraceWriterTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TransactionTraceWriterTest.cpp
@@ -105,4 +105,16 @@
     verifyTraceFile();
 }
 
+// Check we cannot write to file if the trace write is disabled.
+TEST_F(TransactionTraceWriterTest, canDisableTraceWriter) {
+    TransactionTraceWriter::getInstance().disable();
+    TransactionTraceWriter::getInstance().invokeForTest(mFilename, /* overwrite */ true);
+    EXPECT_NE(access(mFilename.c_str(), F_OK), 0);
+
+    TransactionTraceWriter::getInstance().enable();
+    TransactionTraceWriter::getInstance().invokeForTest(mFilename, /* overwrite */ true);
+    EXPECT_EQ(access(mFilename.c_str(), F_OK), 0);
+    verifyTraceFile();
+}
+
 } // namespace android
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