ceph/src/jaegertracing/opentelemetry-cpp/examples/multithreaded/main.cc

   1 // Copyright The OpenTelemetry Authors
   2 // SPDX-License-Identifier: Apache-2.0
   3
   4 #include "opentelemetry/sdk/resource/resource.h"
   5 #include "opentelemetry/sdk/trace/simple_processor.h"
   6 #include "opentelemetry/sdk/trace/tracer_provider.h"
   7 #include "opentelemetry/trace/provider.h"
   8 #include "opentelemetry/trace/scope.h"
   9
  10 // Using an exporter that simply dumps span data to stdout.
  11 #include "opentelemetry/exporters/ostream/span_exporter.h"
  12
  13 #include <algorithm>
  14 #include <thread>
  15
  16 namespace trace_api = opentelemetry::trace;
  17 namespace trace_sdk = opentelemetry::sdk::trace;
  18 namespace nostd     = opentelemetry::nostd;
  19
  20 namespace
  21 {
  22 void initTracer()
  23 {
  24   auto exporter = std::unique_ptr<trace_sdk::SpanExporter>(
  25       new opentelemetry::exporter::trace::OStreamSpanExporter);
  26   auto processor = std::unique_ptr<trace_sdk::SpanProcessor>(
  27       new trace_sdk::SimpleSpanProcessor(std::move(exporter)));
  28   auto provider = nostd::shared_ptr<trace_api::TracerProvider>(new trace_sdk::TracerProvider(
  29       std::move(processor), opentelemetry::sdk::resource::Resource::Create({})));
  30   // Set the global trace provider
  31   trace_api::Provider::SetTracerProvider(provider);
  32 }
  33
  34 nostd::shared_ptr<trace_api::Tracer> get_tracer()
  35 {
  36   auto provider = trace_api::Provider::GetTracerProvider();
  37   return provider->GetTracer("foo_library");
  38 }
  39 }  // namespace
  40
  41 void run_threads()
  42 {
  43   auto thread_span = get_tracer()->StartSpan(__func__);
  44
  45   std::vector<std::thread> threads;
  46   for (int thread_num = 0; thread_num < 5; ++thread_num)
  47   {
  48     // This shows how one can effectively use Scope objects to correctly
  49     // parent spans across threads.
  50     threads.push_back(std::thread([=] {
  51       trace_api::Scope scope(thread_span);
  52       auto thread_span =
  53           get_tracer()->StartSpan(std::string("thread ") + std::to_string(thread_num));
  54     }));
  55   }
  56
  57   std::for_each(threads.begin(), threads.end(), [](std::thread &th) { th.join(); });
  58 }
  59
  60 int main()
  61 {
  62   initTracer();
  63
  64   auto root_span = get_tracer()->StartSpan(__func__);
  65   trace_api::Scope scope(root_span);
  66
  67   run_threads();
  68 }