[profiler] opt-in tracing setting

CpuProfiler includes logic tracing that is only relevant in
the context of TracingCpuProfiler.
Adds a setting to disable tracing for SamplingCpuProfiler.

Change-Id: Idcac03dd3f368b5fcd48a532d5cfe60966a64003
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3433219
Auto-Submit: Corentin Pescheloche <cpescheloche@fb.com>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79190}

include/v8-profiler.h

@@ -306,15 +306,19 @@ class V8_EXPORT CpuProfilingOptions {
    *                             the profiler's sampling interval.
    * \param filter_context If specified, profiles will only contain frames
    *                       using this context. Other frames will be elided.
+   * \param enable_tracing Controls if profiles will log samples as traces
+   *                       events. Defaults to true.
    */
   CpuProfilingOptions(
       CpuProfilingMode mode = kLeafNodeLineNumbers,
       unsigned max_samples = kNoSampleLimit, int sampling_interval_us = 0,
-      MaybeLocal<Context> filter_context = MaybeLocal<Context>());
+      MaybeLocal<Context> filter_context = MaybeLocal<Context>(),
+      bool enable_tracing = true);
 
   CpuProfilingMode mode() const { return mode_; }
   unsigned max_samples() const { return max_samples_; }
   int sampling_interval_us() const { return sampling_interval_us_; }
+  bool enable_tracing() const { return enable_tracing_; }
 
  private:
   friend class internal::CpuProfile;
@@ -326,6 +330,7 @@ class V8_EXPORT CpuProfilingOptions {
   unsigned max_samples_;
   int sampling_interval_us_;
   CopyablePersistentTraits<Context>::CopyablePersistent filter_context_;
+  bool enable_tracing_;
 };
 
 /**

src/api/api.cc

@@ -9873,10 +9873,12 @@ CpuProfiler* CpuProfiler::New(Isolate* isolate,
 CpuProfilingOptions::CpuProfilingOptions(CpuProfilingMode mode,
                                          unsigned max_samples,
                                          int sampling_interval_us,
-                                         MaybeLocal<Context> filter_context)
+                                         MaybeLocal<Context> filter_context,
+                                         bool enable_tracing)
     : mode_(mode),
       max_samples_(max_samples),
-      sampling_interval_us_(sampling_interval_us) {
+      sampling_interval_us_(sampling_interval_us),
+      enable_tracing_(enable_tracing) {
   if (!filter_context.IsEmpty()) {
     Local<Context> local_filter_context = filter_context.ToLocalChecked();
     filter_context_.Reset(local_filter_context->GetIsolate(),

src/profiler/profile-generator.cc

@@ -463,11 +463,14 @@ class DeleteNodesCallback {
   void AfterChildTraversed(ProfileNode*, ProfileNode*) { }
 };
 
-ProfileTree::ProfileTree(Isolate* isolate, CodeEntryStorage* storage)
-    : next_node_id_(1),
+ProfileTree::ProfileTree(Isolate* isolate, CodeEntryStorage* storage,
+                         bool stream_nodes)
+    : pending_nodes_(0),
+      next_node_id_(1),
       isolate_(isolate),
       code_entries_(storage),
-      root_(new ProfileNode(this, CodeEntry::root_entry(), nullptr)) {}
+      root_(new ProfileNode(this, CodeEntry::root_entry(), nullptr)),
+      stream_nodes_(stream_nodes) {}
 
 ProfileTree::~ProfileTree() {
   DeleteNodesCallback cb;
@@ -579,19 +582,22 @@ CpuProfile::CpuProfile(CpuProfiler* profiler, const char* title,
       options_(options),
       delegate_(std::move(delegate)),
       start_time_(base::TimeTicks::Now()),
-      top_down_(profiler->isolate(), profiler->code_entries()),
+      top_down_(profiler->isolate(), profiler->code_entries(),
+                options_.enable_tracing()),
       profiler_(profiler),
       streaming_next_sample_(0),
       id_(++last_id_) {
-  // The startTime timestamp is not converted to Perfetto's clock domain and
-  // will get out of sync with other timestamps Perfetto knows about, including
-  // the automatic trace event "ts" timestamp. startTime is included for
-  // backward compatibility with the tracing protocol but the value of "ts"
-  // should be used instead (it is recorded nearly immediately after).
-  auto value = TracedValue::Create();
-  value->SetDouble("startTime", start_time_.since_origin().InMicroseconds());
-  TRACE_EVENT_SAMPLE_WITH_ID1(TRACE_DISABLED_BY_DEFAULT("v8.cpu_profiler"),
-                              "Profile", id_, "data", std::move(value));
+  if (options.enable_tracing()) {
+    // The startTime timestamp is not converted to Perfetto's clock domain and
+    // will get out of sync with other timestamps Perfetto knows about,
+    // including the automatic trace event "ts" timestamp. startTime is included
+    // for backward compatibility with the tracing protocol but the value of
+    // "ts" should be used instead (it is recorded nearly immediately after).
+    auto value = TracedValue::Create();
+    value->SetDouble("startTime", start_time_.since_origin().InMicroseconds());
+    TRACE_EVENT_SAMPLE_WITH_ID1(TRACE_DISABLED_BY_DEFAULT("v8.cpu_profiler"),
+                                "Profile", id_, "data", std::move(value));
+  }
 
   DisallowHeapAllocation no_gc;
   if (options_.has_filter_context()) {
@@ -687,6 +693,7 @@ void BuildNodeValue(const ProfileNode* node, TracedValue* value) {
 }  // namespace
 
 void CpuProfile::StreamPendingTraceEvents() {
+  if (!options_.enable_tracing()) return;
   std::vector<const ProfileNode*> pending_nodes = top_down_.TakePendingNodes();
   if (pending_nodes.empty() && samples_.empty()) return;
   auto value = TracedValue::Create();
@@ -750,20 +757,23 @@ void CpuProfile::StreamPendingTraceEvents() {
 }
 
 void CpuProfile::FinishProfile() {
-  end_time_ = base::TimeTicks::Now();
   // Stop tracking context movements after profiling stops.
   context_filter_.set_native_context_address(kNullAddress);
-  StreamPendingTraceEvents();
-  auto value = TracedValue::Create();
-  // The endTime timestamp is not converted to Perfetto's clock domain and will
-  // get out of sync with other timestamps Perfetto knows about, including the
-  // automatic trace event "ts" timestamp. endTime is included for backward
-  // compatibility with the tracing protocol: its presence in "data" is used by
-  // devtools to identify the last ProfileChunk but the value of "ts" should be
-  // used instead (it is recorded nearly immediately after).
-  value->SetDouble("endTime", end_time_.since_origin().InMicroseconds());
-  TRACE_EVENT_SAMPLE_WITH_ID1(TRACE_DISABLED_BY_DEFAULT("v8.cpu_profiler"),
-                              "ProfileChunk", id_, "data", std::move(value));
+  if (options_.enable_tracing()) {
+    end_time_ = base::TimeTicks::Now();
+    StreamPendingTraceEvents();
+    auto value = TracedValue::Create();
+    // The endTime timestamp is not converted to Perfetto's clock domain and
+    // will get out of sync with other timestamps Perfetto knows about,
+    // including the automatic trace event "ts" timestamp. endTime is included
+    // for backward compatibility with the tracing protocol: its presence in
+    // "data" is used by devtools to identify the last ProfileChunk but the
+    // value of "ts" should be used instead (it is recorded nearly immediately
+    // after).
+    value->SetDouble("endTime", end_time_.since_origin().InMicroseconds());
+    TRACE_EVENT_SAMPLE_WITH_ID1(TRACE_DISABLED_BY_DEFAULT("v8.cpu_profiler"),
+                                "ProfileChunk", id_, "data", std::move(value));
+  }
 }
 
 void CpuProfile::Print() const {

src/profiler/profile-generator.h

@@ -355,7 +355,8 @@ class CodeEntryStorage;
 
 class V8_EXPORT_PRIVATE ProfileTree {
  public:
-  explicit ProfileTree(Isolate* isolate, CodeEntryStorage* storage = nullptr);
+  explicit ProfileTree(Isolate* isolate, CodeEntryStorage* storage = nullptr,
+                       bool stream_nodes = true);
   ~ProfileTree();
   ProfileTree(const ProfileTree&) = delete;
   ProfileTree& operator=(const ProfileTree&) = delete;
@@ -378,7 +379,9 @@ class V8_EXPORT_PRIVATE ProfileTree {
 
   Isolate* isolate() const { return isolate_; }
 
-  void EnqueueNode(const ProfileNode* node) { pending_nodes_.push_back(node); }
+  void EnqueueNode(const ProfileNode* node) {
+    if (stream_nodes_) pending_nodes_.push_back(node);
+  }
   size_t pending_nodes_count() const { return pending_nodes_.size(); }
   std::vector<const ProfileNode*> TakePendingNodes() {
     return std::move(pending_nodes_);
@@ -396,6 +399,7 @@ class V8_EXPORT_PRIVATE ProfileTree {
   Isolate* isolate_;
   CodeEntryStorage* const code_entries_;
   ProfileNode* root_;
+  bool stream_nodes_;
 };
 
 class CpuProfiler;

test/cctest/test-cpu-profiler.cc

@@ -2996,6 +2996,90 @@ TEST(TracingCpuProfiler) {
 #endif  // !V8_USE_PERFETTO
 }
 
+TEST(DisableTracing) {
+  v8::HandleScope scope(CcTest::isolate());
+  v8::Local<v8::Context> env = CcTest::NewContext({PROFILER_EXTENSION_ID});
+  v8::Context::Scope context_scope(env);
+
+  auto* tracing_controller =
+      static_cast<v8::platform::tracing::TracingController*>(
+          i::V8::GetCurrentPlatform()->GetTracingController());
+
+// Event checks throws if events are received from multiple ID
+#ifdef V8_USE_PERFETTO
+  std::ostringstream perfetto_output;
+  tracing_controller->InitializeForPerfetto(&perfetto_output);
+  CpuProfilerListener listener;
+  tracing_controller->SetTraceEventListenerForTesting(&listener);
+#else
+  CpuProfileEventChecker* event_checker = new CpuProfileEventChecker();
+  TraceBuffer* ring_buffer =
+      TraceBuffer::CreateTraceBufferRingBuffer(1, event_checker);
+  tracing_controller->Initialize(ring_buffer);
+#endif
+
+  i::Isolate* isolate = CcTest::i_isolate();
+
+  CodeEntryStorage storage;
+  CpuProfilesCollection* profiles = new CpuProfilesCollection(isolate);
+  ProfilerCodeObserver* code_observer =
+      new ProfilerCodeObserver(isolate, storage);
+
+  CpuProfiler profiler(isolate, kDebugNaming, kEagerLogging, profiles, nullptr,
+                       nullptr, code_observer);
+
+  TraceConfig* trace_config = new TraceConfig();
+  trace_config->AddIncludedCategory(
+      TRACE_DISABLED_BY_DEFAULT("v8.cpu_profiler"));
+
+  tracing_controller->StartTracing(trace_config);
+#ifdef V8_USE_PERFETTO
+  TrackEvent::Flush();
+#endif
+
+  // Start Non tracing profiler configured no to log events in tracing system
+  CpuProfilingOptions options(kLeafNodeLineNumbers, 0, 0,
+                              MaybeLocal<v8::Context>(), false);
+  profiler.StartProfiling("test", options);
+  CompileRun(
+      "function some_func() {}"
+
+      "some_func();");
+  profiler.StopProfiling("test");
+#ifdef V8_USE_PERFETTO
+  std::string profile_json = listener.result_json();
+  listener.Reset();
+#else
+  tracing_controller->StopTracing();
+
+  std::string profile_json = event_checker->result_json();
+  event_checker->Reset();
+#endif
+
+  CHECK_LT(0u, profile_json.length());
+  printf("Profile JSON: %s\n", profile_json.c_str());
+
+  std::string profile_checker_code = R"(
+        function checkProfile(json) {
+          const profile_header = json[0];
+          if (typeof profile_header['startTime'] !== 'number')
+            return false;
+          return json.some(event => (event.lines || []).some(line => line)) &&
+              json.filter(e => e.cpuProfile && e.cpuProfile.nodes)
+              .some(e => e.cpuProfile.nodes
+                  .some(n => n.callFrame.codeType == "JS"));
+        }
+        checkProfile()" + profile_json +
+                                     ")";
+  CompileRunChecked(CcTest::isolate(), profile_checker_code.c_str())->IsTrue();
+
+#ifndef V8_USE_PERFETTO
+  static_cast<v8::platform::tracing::TracingController*>(
+      i::V8::GetCurrentPlatform()->GetTracingController())
+      ->Initialize(nullptr);
+#endif  // !V8_USE_PERFETTO
+}
+
 TEST(Issue763073) {
   class AllowNativesSyntax {
    public: