138 lines
4.8 KiB
C++
138 lines
4.8 KiB
C++
/*
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* Copyright (C) 2022 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 startup tracing with a custom data source.
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// Startup tracing can work only with kSystemBackend. Before running
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// this example, `traced` must already be running in a separate process.
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// Run system tracing: ninja -C out/default/ traced && ./out/default/traced
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// And then run this example: ninja -C out/default example_startup_trace &&
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// ./out/default/example_startup_trace
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#if defined(PERFETTO_SDK_EXAMPLE_USE_INTERNAL_HEADERS)
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#include "perfetto/tracing.h"
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#include "perfetto/tracing/core/data_source_descriptor.h"
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#include "perfetto/tracing/core/trace_config.h"
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#include "perfetto/tracing/data_source.h"
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#include "perfetto/tracing/tracing.h"
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#include "protos/perfetto/trace/test_event.pbzero.h"
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#else
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#include <perfetto.h>
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#endif
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#include <fstream>
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#include <iostream>
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#include <thread>
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namespace {
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// The definition of our custom data source. Instances of this class will be
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// automatically created and destroyed by Perfetto.
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class CustomDataSource : public perfetto::DataSource<CustomDataSource> {};
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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 system-wide tracing service, because the in-process
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// backend doesn't support startup tracing.
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args.backends = perfetto::kSystemBackend;
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perfetto::Tracing::Initialize(args);
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// Register our custom data source. Only the name is required, but other
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// properties can be advertised too.
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perfetto::DataSourceDescriptor dsd;
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dsd.set_name("com.example.startup_trace");
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CustomDataSource::Register(dsd);
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}
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// The trace config defines which types of data sources are enabled for
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// recording.
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perfetto::TraceConfig GetTraceConfig() {
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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("com.example.startup_trace");
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return cfg;
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}
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void StartStartupTracing() {
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perfetto::Tracing::SetupStartupTracingOpts args;
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args.backend = perfetto::kSystemBackend;
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perfetto::Tracing::SetupStartupTracingBlocking(GetTraceConfig(), args);
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}
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std::unique_ptr<perfetto::TracingSession> StartTracing() {
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auto tracing_session = perfetto::Tracing::NewTrace();
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tracing_session->Setup(GetTraceConfig());
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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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// Flush to make sure the last written event ends up in the trace.
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CustomDataSource::Trace(
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[](CustomDataSource::TraceContext ctx) { ctx.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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const char* filename = "example_startup_trace.pftrace";
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output.open(filename, std::ios::out | std::ios::binary);
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output.write(trace_data.data(),
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static_cast<std::streamsize>(trace_data.size()));
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output.close();
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PERFETTO_LOG(
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"Trace written in %s file. To read this trace in "
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"text form, run `./tools/traceconv text %s`",
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filename, filename);
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}
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} // namespace
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PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS(CustomDataSource);
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PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS(CustomDataSource);
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int main(int, const char**) {
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InitializePerfetto();
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StartStartupTracing();
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// Write an event using our custom data source before starting tracing
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// session.
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CustomDataSource::Trace([](CustomDataSource::TraceContext ctx) {
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auto packet = ctx.NewTracePacket();
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packet->set_timestamp(41);
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packet->set_for_testing()->set_str("Startup Event");
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});
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auto tracing_session = StartTracing();
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// Write an event using our custom data source.
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CustomDataSource::Trace([](CustomDataSource::TraceContext ctx) {
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auto packet = ctx.NewTracePacket();
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packet->set_timestamp(42);
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packet->set_for_testing()->set_str("Main Event");
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});
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StopTracing(std::move(tracing_session));
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return 0;
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}
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