| /* |
| * Copyright (C) 2020 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| // This example demonstrates in-process tracing with Perfetto. |
| |
| #include "trace_categories.h" |
| |
| #include <chrono> |
| #include <fstream> |
| #include <thread> |
| |
| void InitializePerfetto() { |
| perfetto::TracingInitArgs args; |
| // The backends determine where trace events are recorded. For this example we |
| // are going to use the in-process tracing service, which only includes in-app |
| // events. |
| args.backends = perfetto::kInProcessBackend; |
| |
| perfetto::Tracing::Initialize(args); |
| perfetto::TrackEvent::Register(); |
| } |
| |
| std::unique_ptr<perfetto::TracingSession> StartTracing() { |
| // The trace config defines which types of data sources are enabled for |
| // recording. In this example we just need the "track_event" data source, |
| // which corresponds to the TRACE_EVENT trace points. |
| perfetto::TraceConfig cfg; |
| cfg.add_buffers()->set_size_kb(1024); |
| auto* ds_cfg = cfg.add_data_sources()->mutable_config(); |
| ds_cfg->set_name("track_event"); |
| |
| auto tracing_session = perfetto::Tracing::NewTrace(); |
| tracing_session->Setup(cfg); |
| tracing_session->StartBlocking(); |
| return tracing_session; |
| } |
| |
| void StopTracing(std::unique_ptr<perfetto::TracingSession> tracing_session) { |
| // Make sure the last event is closed for this example. |
| perfetto::TrackEvent::Flush(); |
| |
| // Stop tracing and read the trace data. |
| tracing_session->StopBlocking(); |
| std::vector<char> trace_data(tracing_session->ReadTraceBlocking()); |
| |
| // Write the result into a file. |
| // Note: To save memory with longer traces, you can tell Perfetto to write |
| // directly into a file by passing a file descriptor into Setup() above. |
| std::ofstream output; |
| output.open("example.pftrace", std::ios::out | std::ios::binary); |
| output.write(&trace_data[0], trace_data.size()); |
| output.close(); |
| } |
| |
| void DrawPlayer(int player_number) { |
| TRACE_EVENT("rendering", "DrawPlayer", "player_number", player_number); |
| // Sleep to simulate a long computation. |
| std::this_thread::sleep_for(std::chrono::milliseconds(500)); |
| } |
| |
| void DrawGame() { |
| // This is an example of an unscoped slice, which begins and ends at specific |
| // points (instead of at the end of the current block scope). |
| TRACE_EVENT_BEGIN("rendering", "DrawGame"); |
| DrawPlayer(1); |
| DrawPlayer(2); |
| TRACE_EVENT_END("rendering"); |
| |
| // Record the rendering framerate as a counter sample. |
| TRACE_COUNTER("rendering", "Framerate", 120); |
| } |
| |
| int main(int, const char**) { |
| InitializePerfetto(); |
| auto tracing_session = StartTracing(); |
| |
| // Give a custom name for the traced process. |
| perfetto::ProcessTrack process_track = perfetto::ProcessTrack::Current(); |
| perfetto::protos::gen::TrackDescriptor desc = process_track.Serialize(); |
| desc.mutable_process()->set_process_name("Example"); |
| perfetto::TrackEvent::SetTrackDescriptor(process_track, desc); |
| |
| // Simulate some work that emits trace events. |
| DrawGame(); |
| |
| StopTracing(std::move(tracing_session)); |
| return 0; |
| } |