metrics histogram example (#1330)

examples/common/metrics_foo_library/foo_library.cc

@@ -2,24 +2,59 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #ifndef ENABLE_METRICS_PREVIEW
+#  include "foo_library.h"
 #  include <chrono>
+#  include <map>
 #  include <thread>
 #  include "opentelemetry/metrics/provider.h"
 
 namespace nostd       = opentelemetry::nostd;
 namespace metrics_api = opentelemetry::metrics;
 
-void foo_library(const std::string &name)
+namespace
 {
-  // Get the Meter from the MeterProvider
+std::map<std::string, std::string> get_random_attr()
+{
+  static const std::vector<std::pair<std::string, std::string>> labels = {{"key1", "value1"},
+                                                                          {"key2", "value2"},
+                                                                          {"key3", "value3"},
+                                                                          {"key4", "value4"},
+                                                                          {"key5", "value5"}};
+  return std::map<std::string, std::string>{labels[rand() % (labels.size() - 1)],
+                                            labels[rand() % (labels.size() - 1)]};
+}
+}  // namespace
+
+void foo_library::counter_example(const std::string &name)
+{
+  std::string counter_name                    = name + "_counter";
   auto provider                               = metrics_api::Provider::GetMeterProvider();
   nostd::shared_ptr<metrics_api::Meter> meter = provider->GetMeter(name, "1.2.0");
-  auto double_counter                         = meter->CreateDoubleCounter(name);
-  double_counter->Add(28.5);
-  std::this_thread::sleep_for(std::chrono::milliseconds(500));
-  double_counter->Add(3.14);
-  std::this_thread::sleep_for(std::chrono::milliseconds(500));
-  double_counter->Add(23.5);
-  std::this_thread::sleep_for(std::chrono::milliseconds(5000));
+  auto double_counter                         = meter->CreateDoubleCounter(counter_name);
+
+  while (true)
+  {
+    double val = (rand() % 700) + 1.1;
+    double_counter->Add(val);
+    std::this_thread::sleep_for(std::chrono::milliseconds(500));
+  }
 }
+
+void foo_library::histogram_example(const std::string &name)
+{
+  std::string histogram_name                  = name + "_histogram";
+  auto provider                               = metrics_api::Provider::GetMeterProvider();
+  nostd::shared_ptr<metrics_api::Meter> meter = provider->GetMeter(name, "1.2.0");
+  auto histogram_counter                      = meter->CreateDoubleHistogram(histogram_name);
+  auto context                                = opentelemetry::context::Context{};
+  while (true)
+  {
+    double val                                = (rand() % 700) + 1.1;
+    std::map<std::string, std::string> labels = get_random_attr();
+    auto labelkv = opentelemetry::common::KeyValueIterableView<decltype(labels)>{labels};
+    histogram_counter->Record(val, labelkv, context);
+    std::this_thread::sleep_for(std::chrono::milliseconds(250));
+  }
+}
+
 #endif

examples/common/metrics_foo_library/foo_library.h

@@ -5,5 +5,10 @@
 #ifndef ENABLE_METRICS_PREVIEW
 #  include <string>
 
-void foo_library(const std::string &name);
+class foo_library
+{
+public:
+  static void counter_example(const std::string &name);
+  static void histogram_example(const std::string &name);
+};
 #endif

examples/metrics_simple/metrics_ostream.cc

@@ -3,6 +3,7 @@
 
 #ifndef ENABLE_METRICS_PREVIEW
 #  include <memory>
+#  include <thread>
 #  include "opentelemetry/exporters/ostream/metric_exporter.h"
 #  include "opentelemetry/metrics/provider.h"
 #  include "opentelemetry/sdk/metrics/aggregation/default_aggregation.h"
@@ -44,21 +45,57 @@ void initMetrics(const std::string &name)
       new metric_sdk::MeterProvider(std::move(exporters)));
   auto p = std::static_pointer_cast<metric_sdk::MeterProvider>(provider);
   p->AddMetricReader(std::move(reader));
+
+  // counter view
+  std::string counter_name = name + "_counter";
   std::unique_ptr<metric_sdk::InstrumentSelector> instrument_selector{
-      new metric_sdk::InstrumentSelector(metric_sdk::InstrumentType::kCounter, name)};
+      new metric_sdk::InstrumentSelector(metric_sdk::InstrumentType::kCounter, counter_name)};
   std::unique_ptr<metric_sdk::MeterSelector> meter_selector{
       new metric_sdk::MeterSelector(name, version, schema)};
-  std::unique_ptr<metric_sdk::View> view{
+  std::unique_ptr<metric_sdk::View> sum_view{
       new metric_sdk::View{name, "description", metric_sdk::AggregationType::kSum}};
-  p->AddView(std::move(instrument_selector), std::move(meter_selector), std::move(view));
+  p->AddView(std::move(instrument_selector), std::move(meter_selector), std::move(sum_view));
+
+  // histogram view
+  std::string histogram_name = name + "_histogram";
+  std::unique_ptr<metric_sdk::InstrumentSelector> histogram_instrument_selector{
+      new metric_sdk::InstrumentSelector(metric_sdk::InstrumentType::kHistogram, histogram_name)};
+  std::unique_ptr<metric_sdk::MeterSelector> histogram_meter_selector{
+      new metric_sdk::MeterSelector(name, version, schema)};
+  std::unique_ptr<metric_sdk::View> histogram_view{
+      new metric_sdk::View{name, "description", metric_sdk::AggregationType::kHistogram}};
+  p->AddView(std::move(histogram_instrument_selector), std::move(histogram_meter_selector),
+             std::move(histogram_view));
   metrics_api::Provider::SetMeterProvider(provider);
 }
 }  // namespace
-int main()
+
+int main(int argc, char **argv)
 {
+  std::string example_type;
+  if (argc >= 2)
+  {
+    example_type = argv[1];
+  }
+
   std::string name{"ostream_metric_example"};
   initMetrics(name);
-  foo_library(name);
+
+  if (example_type == "counter")
+  {
+    foo_library::counter_example(name);
+  }
+  else if (example_type == "histogram")
+  {
+    foo_library::histogram_example(name);
+  }
+  else
+  {
+    std::thread counter_example{&foo_library::counter_example, name};
+    std::thread histogram_example{&foo_library::histogram_example, name};
+    counter_example.join();
+    histogram_example.join();
+  }
 }
 #else
 int main() {}

exporters/ostream/src/metric_exporter.cc

@@ -59,6 +59,8 @@ sdk::common::ExportResult OStreamMetricExporter::Export(
 void OStreamMetricExporter::printInstrumentationInfoMetricData(
     const sdk::metrics::InstrumentationInfoMetrics &info_metric)
 {
+  // sout_ is shared
+  const std::lock_guard<opentelemetry::common::SpinLockMutex> locked(lock_);
   sout_ << "{";
   sout_ << "\n  name\t\t: " << info_metric.instrumentation_library_->GetName()
         << "\n  schema url\t: " << info_metric.instrumentation_library_->GetSchemaURL()