Add custom stats to gRPC example. (#132)

Author: g-easy

examples/grpc/README.md

@@ -13,7 +13,7 @@ Usage:
 ```shell
 bazel build :all
 ../../bazel-bin/examples/grpc/hello_server 9001
-../../bazel-bin/examples/grpc/hello_client [::]:9001
+../../bazel-bin/examples/grpc/hello_client "[::]:9001"
 ```
 
 You can see the Prometheus stats on http://127.0.0.1:8080/metrics

examples/grpc/hello_client.cc

@@ -38,11 +38,15 @@ using examples::HelloService;
 }  // namespace
 
 int main(int argc, char** argv) {
-  if (argc != 2) {
-    std::cerr << "Usage: " << argv[0] << " host:port\n";
+  if (argc < 2) {
+    std::cerr << "Usage: " << argv[0] << " host:port [name]\n";
     return 1;
   }
   const std::string hostport = argv[1];
+  std::string name = "world";
+  if (argc >= 3) {
+    name = argv[2];
+  }
 
   // Register the OpenCensus gRPC plugin to enable stats and tracing in gRPC.
   opencensus::RegisterGrpcPlugin();
@@ -69,7 +73,7 @@ int main(int argc, char** argv) {
     grpc::ClientContext ctx;
     HelloRequest request;
     HelloReply reply;
-    request.set_name("world");
+    request.set_name(name);
     std::cout << "Sending request: \"" << request.ShortDebugString() << "\"\n";
 
     grpc::Status status = stub->SayHello(&ctx, request, &reply);

examples/grpc/hello_server.cc

@@ -32,6 +32,7 @@
 #include "opencensus/exporters/trace/stackdriver/stackdriver_exporter.h"
 #include "opencensus/exporters/trace/stdout/stdout_exporter.h"
 #include "opencensus/plugins/grpc/grpc_plugin.h"
+#include "opencensus/stats/stats.h"
 #include "opencensus/trace/sampler.h"
 #include "opencensus/trace/span.h"
 #include "opencensus/trace/trace_config.h"
@@ -43,6 +44,22 @@ using examples::HelloReply;
 using examples::HelloRequest;
 using examples::HelloService;
 
+ABSL_CONST_INIT const char kLettersMeasureName[] =
+    "example.org/measure/letters";
+
+opencensus::stats::MeasureInt64 LettersMeasure() {
+  static const opencensus::stats::MeasureInt64 measure =
+      opencensus::stats::MeasureInt64::Register(
+          kLettersMeasureName, "Number of letters in processed names.", "By");
+  return measure;
+}
+
+opencensus::stats::TagKey CaseKey() {
+  static const opencensus::stats::TagKey key =
+      opencensus::stats::TagKey::Register("example_uppercased");
+  return key;
+}
+
 // A helper function that performs some work in its own Span.
 void PerformWork(opencensus::trace::Span* parent) {
   auto span = opencensus::trace::Span::StartSpan("internal_work", parent);
@@ -67,7 +84,10 @@ class HelloServiceImpl final : public HelloService::Service {
     PerformWork(&span);
     span.AddAnnotation("Sleeping.");
     absl::SleepFor(absl::Milliseconds(30));
-    // TODO: Record() custom stats.
+    // Record custom stats.
+    opencensus::stats::Record(
+        {{LettersMeasure(), request->name().size()}},
+        {{CaseKey(), isupper(request->name()[0]) ? "upper" : "lower"}});
     std::cerr << "SayHello RPC handled.\n";
     return grpc::Status::OK;
   }
@@ -106,6 +126,21 @@ int main(int argc, char** argv) {
   prometheus::Exposer exposer("127.0.0.1:8080");
   exposer.RegisterCollectable(exporter);
 
+  // Init custom measure.
+  LettersMeasure();
+
+  // Add a View for custom stats.
+  const opencensus::stats::ViewDescriptor letters_view =
+      opencensus::stats::ViewDescriptor()
+          .set_name("example.org/view/letters_view")
+          .set_description("number of letters in names greeted over time")
+          .set_measure(kLettersMeasureName)
+          .set_aggregation(opencensus::stats::Aggregation::Sum())
+          .add_column(CaseKey());
+  opencensus::stats::View view(letters_view);
+  assert(view.IsValid());
+  letters_view.RegisterForExport();
+
   // Start the RPC server. You shouldn't see any output from gRPC before this.
   std::cerr << "gRPC starting.\n";
   HelloServiceImpl service;