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/*
* 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 system-wide tracing with Perfetto.
#include "trace_categories.h"
#include <chrono>
#include <condition_variable>
#include <fstream>
#include <thread>
class Observer : public perfetto::TrackEventSessionObserver {
public:
Observer() { perfetto::TrackEvent::AddSessionObserver(this); }
~Observer() { perfetto::TrackEvent::RemoveSessionObserver(this); }
void OnStart(const perfetto::DataSourceBase::StartArgs&) override {
std::unique_lock<std::mutex> lock(mutex);
cv.notify_one();
}
void WaitForTracingStart() {
PERFETTO_LOG("Waiting for tracing to start...");
std::unique_lock<std::mutex> lock(mutex);
cv.wait(lock, [] { return perfetto::TrackEvent::IsEnabled(); });
PERFETTO_LOG("Tracing started");
}
std::mutex mutex;
std::condition_variable cv;
};
void InitializePerfetto() {
perfetto::TracingInitArgs args;
// The backends determine where trace events are recorded. For this example we
// are going to use the system-wide tracing service, so that we can see our
// app's events in context with system profiling information.
args.backends = perfetto::kSystemBackend;
perfetto::Tracing::Initialize(args);
perfetto::TrackEvent::Register();
}
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() {
TRACE_EVENT("rendering", "DrawGame");
DrawPlayer(1);
DrawPlayer(2);
}
int main(int, const char**) {
InitializePerfetto();
Observer observer;
observer.WaitForTracingStart();
// Simulate some work that emits trace events.
// Note that we don't start and stop tracing here; for system-wide tracing
// this needs to be done through the "perfetto" command line tool or the
// Perfetto UI (https://ui.perfetto.dev).
DrawGame();
// Make sure the last event is closed for this example.
perfetto::TrackEvent::Flush();
return 0;
}