Client API: Allow data sources to handle Stop asynchronously
Exposes the ability to defer tracing session stop to the public
producer-side API. This feature was already part of the tracing
protocol but was not exposed to the public API surface.
Also makes some minor cleanups:
- Rename instance_state->started to trace_lambda_enabled
to better reflect what the field does.
- Rename {android_,}client_api_example as the code is not really
Android-specific.
Bug: 132678367
Bug: 137210068
Change-Id: I446d2ce9df1c9d4517a8b078813b9cc4138aef20diff --git a/test/client_api_example.cc b/test/client_api_example.cc
new file mode 100644
index 0000000..f43bd98
--- /dev/null
+++ b/test/client_api_example.cc
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#include "perfetto/tracing.h"
+
+#include <thread>
+
+#include "perfetto/trace/test_event.pbzero.h"
+#include "perfetto/trace/trace_packet.pbzero.h"
+
+// Deliberately not pulling any non-public perfetto header to spot accidental
+// header public -> non-public dependency while building this file.
+
+namespace {
+
+class MyDataSource : public perfetto::DataSource<MyDataSource> {
+ public:
+ void OnSetup(const SetupArgs& args) override {
+ // This can be used to access the domain-specific DataSourceConfig, via
+ // args.config->xxx_config_raw().
+ PERFETTO_ILOG("OnSetup called, name: %s", args.config->name().c_str());
+ }
+
+ void OnStart(const StartArgs&) override { PERFETTO_ILOG("OnStart called"); }
+
+ void OnStop(const StopArgs& args) override {
+ PERFETTO_ILOG("OnStop called");
+
+ // Demonstrates the ability to defer stop and handle it asynchronously,
+ // writing data at the very end of the trace.
+ auto stop_closure = args.HandleStopAsynchronously();
+ std::thread another_thread([stop_closure] {
+ sleep(2);
+ MyDataSource::Trace([](MyDataSource::TraceContext ctx) {
+ PERFETTO_LOG("Tracing lambda called while stopping");
+ auto packet = ctx.NewTracePacket();
+ packet->set_for_testing()->set_str("event recorded while stopping");
+ packet->Finalize(); // Required because of the Flush below.
+
+ // This explicit Flush() is required because the service doesn't issue
+ // any other flush requests after the Stop() signal.
+ ctx.Flush();
+ });
+ stop_closure();
+ });
+ another_thread.detach();
+ }
+};
+
+} // namespace
+
+PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS(MyDataSource);
+
+int main() {
+ perfetto::TracingInitArgs args;
+ args.backends = perfetto::kSystemBackend;
+ perfetto::Tracing::Initialize(args);
+
+ // DataSourceDescriptor can be used to advertise domain-specific features.
+ perfetto::DataSourceDescriptor dsd;
+ dsd.set_name("com.example.mytrace");
+ MyDataSource::Register(dsd);
+
+ for (;;) {
+ MyDataSource::Trace([](MyDataSource::TraceContext ctx) {
+ PERFETTO_LOG("Tracing lambda called");
+ auto packet = ctx.NewTracePacket();
+ packet->set_timestamp(42);
+ packet->set_for_testing()->set_str("event 1");
+ });
+ sleep(1);
+ }
+}
