sdk: Add example code
Add SDK example code imported from https://github.com/skyostil/perfetto-sdk-example
Change-Id: Ic3a478091575d7129e39114d4b0c4280137b5f40
diff --git a/examples/sdk/example_custom_data_source.cc b/examples/sdk/example_custom_data_source.cc
new file mode 100644
index 0000000..2d475c1
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+++ b/examples/sdk/example_custom_data_source.cc
@@ -0,0 +1,103 @@
+/*
+ * 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 a custom tracing data source.
+
+#include <perfetto.h>
+
+#include <fstream>
+#include <thread>
+
+// The definition of our custom data source. Instances of this class will be
+// automatically created and destroyed by Perfetto.
+class CustomDataSource : public perfetto::DataSource<CustomDataSource> {
+ public:
+ void OnSetup(const SetupArgs&) override {
+ // Use this callback to apply any custom configuration to your data source
+ // based on the TraceConfig in SetupArgs.
+ }
+
+ // Optional callbacks for tracking the lifecycle of the data source.
+ void OnStart(const StartArgs&) override {}
+ void OnStop(const StopArgs&) override {}
+};
+
+PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS(CustomDataSource);
+PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS(CustomDataSource);
+
+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);
+
+ // Register our custom data source. Only the name is required, but other
+ // properties can be advertised too.
+ perfetto::DataSourceDescriptor dsd;
+ dsd.set_name("com.example.custom_data_source");
+ CustomDataSource::Register(dsd);
+}
+
+std::unique_ptr<perfetto::TracingSession> StartTracing() {
+ // The trace config defines which types of data sources are enabled for
+ // recording. In this example we enable the custom data source we registered
+ // above.
+ perfetto::TraceConfig cfg;
+ cfg.add_buffers()->set_size_kb(1024);
+ auto* ds_cfg = cfg.add_data_sources()->mutable_config();
+ ds_cfg->set_name("com.example.custom_data_source");
+
+ 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) {
+ // Flush to make sure the last written event ends up in the trace.
+ CustomDataSource::Trace(
+ [](CustomDataSource::TraceContext ctx) { ctx.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_custom_data_source.pftrace",
+ std::ios::out | std::ios::binary);
+ output.write(&trace_data[0], trace_data.size());
+ output.close();
+}
+
+int main(int, const char**) {
+ InitializePerfetto();
+ auto tracing_session = StartTracing();
+
+ // Write an event using our custom data source.
+ CustomDataSource::Trace([](CustomDataSource::TraceContext ctx) {
+ auto packet = ctx.NewTracePacket();
+ packet->set_timestamp(42);
+ packet->set_for_testing()->set_str("Hello world!");
+ });
+
+ StopTracing(std::move(tracing_session));
+ return 0;
+}
