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