Stackdriver Stats exporter: allow override of metric_service_stub. (#348)

Author: g-easy

examples/grpc/stackdriver.cc

@@ -58,6 +58,8 @@ void RegisterStackdriverExporters() {
   opencensus::exporters::trace::StackdriverOptions trace_opts;
   trace_opts.project_id = project_id;
 
-  opencensus::exporters::stats::StackdriverExporter::Register(stats_opts);
-  opencensus::exporters::trace::StackdriverExporter::Register(trace_opts);
+  opencensus::exporters::stats::StackdriverExporter::Register(
+      std::move(stats_opts));
+  opencensus::exporters::trace::StackdriverExporter::Register(
+      std::move(trace_opts));
 }

opencensus/exporters/stats/stackdriver/internal/stackdriver_exporter.cc

@@ -47,7 +47,7 @@ constexpr char kDefaultMetricNamePrefix[] = "custom.googleapis.com/opencensus/";
 
 class Handler : public ::opencensus::stats::StatsExporter::Handler {
  public:
-  explicit Handler(const StackdriverOptions& opts);
+  explicit Handler(StackdriverOptions&& opts);
 
   void ExportViewData(
       const std::vector<std::pair<opencensus::stats::ViewDescriptor,
@@ -64,26 +64,33 @@ class Handler : public ::opencensus::stats::StatsExporter::Handler {
       EXCLUSIVE_LOCKS_REQUIRED(mu_);
 
   const StackdriverOptions opts_;
-  const std::string project_id_;
-  const std::string metric_name_prefix_;
-  const std::unique_ptr<google::monitoring::v3::MetricService::Stub> stub_;
   mutable absl::Mutex mu_;
   std::unordered_map<std::string, opencensus::stats::ViewDescriptor>
       registered_descriptors_ GUARDED_BY(mu_);
 };
 
-Handler::Handler(const StackdriverOptions& opts)
-    : opts_(opts),
-      project_id_(absl::StrCat(kProjectIdPrefix, opts.project_id)),
-      metric_name_prefix_(opts.metric_name_prefix.empty()
-                              ? kDefaultMetricNamePrefix
-                              : opts.metric_name_prefix),
-      stub_(google::monitoring::v3::MetricService::NewStub(
-          ::grpc::CreateCustomChannel(kGoogleStackdriverStatsAddress,
-                                      ::grpc::GoogleDefaultCredentials(),
-                                      ::opencensus::common::WithUserAgent()))) {
+StackdriverOptions SetOptionDefaults(StackdriverOptions&& o) {
+  StackdriverOptions opts(std::move(o));
+
+  // Prepend prefix because we always use this with a prefix.
+  opts.project_id = absl::StrCat(kProjectIdPrefix, opts.project_id);
+
+  if (opts.metric_name_prefix.empty()) {
+    opts.metric_name_prefix = kDefaultMetricNamePrefix;
+  }
+
+  if (opts.metric_service_stub == nullptr) {
+    opts.metric_service_stub = google::monitoring::v3::MetricService::NewStub(
+        ::grpc::CreateCustomChannel(kGoogleStackdriverStatsAddress,
+                                    ::grpc::GoogleDefaultCredentials(),
+                                    ::opencensus::common::WithUserAgent()));
+  }
+  return opts;
 }
 
+Handler::Handler(StackdriverOptions&& opts)
+    : opts_(SetOptionDefaults(std::move(opts))) {}
+
 void Handler::ExportViewData(
     const std::vector<std::pair<opencensus::stats::ViewDescriptor,
                                 opencensus::stats::ViewData>>& data) {
@@ -95,7 +102,7 @@ void Handler::ExportViewData(
       continue;
     }
     const auto view_time_series =
-        MakeTimeSeries(metric_name_prefix_, opts_.monitored_resource,
+        MakeTimeSeries(opts_.metric_name_prefix, opts_.monitored_resource,
                        opts_.per_metric_monitored_resource, datum.first,
                        datum.second, opts_.opencensus_task);
     time_series.insert(time_series.end(), view_time_series.begin(),
@@ -113,15 +120,16 @@ void Handler::ExportViewData(
 
   for (int rpc_index = 0; rpc_index < num_rpcs; ++rpc_index) {
     auto request = google::monitoring::v3::CreateTimeSeriesRequest();
-    request.set_name(project_id_);
+    request.set_name(opts_.project_id);
     const int batch_end = std::min(static_cast<int>(time_series.size()),
                                    (rpc_index + 1) * kTimeSeriesBatchSize);
     for (int i = rpc_index * kTimeSeriesBatchSize; i < batch_end; ++i) {
       *request.add_time_series() = time_series[i];
     }
     ctx[rpc_index].set_deadline(
         absl::ToChronoTime(absl::Now() + opts_.rpc_deadline));
-    auto rpc(stub_->AsyncCreateTimeSeries(&ctx[rpc_index], request, &cq));
+    auto rpc(opts_.metric_service_stub->AsyncCreateTimeSeries(&ctx[rpc_index],
+                                                              request, &cq));
     rpc->Finish(&response, &status[rpc_index], (void*)(uintptr_t)rpc_index);
   }
 
@@ -153,14 +161,14 @@ bool Handler::MaybeRegisterView(
   }
 
   auto request = google::monitoring::v3::CreateMetricDescriptorRequest();
-  request.set_name(project_id_);
-  SetMetricDescriptor(project_id_, metric_name_prefix_, descriptor,
+  request.set_name(opts_.project_id);
+  SetMetricDescriptor(opts_.project_id, opts_.metric_name_prefix, descriptor,
                       request.mutable_metric_descriptor());
   ::grpc::ClientContext context;
   context.set_deadline(absl::ToChronoTime(absl::Now() + opts_.rpc_deadline));
   google::api::MetricDescriptor response;
-  ::grpc::Status status =
-      stub_->CreateMetricDescriptor(&context, request, &response);
+  ::grpc::Status status = opts_.metric_service_stub->CreateMetricDescriptor(
+      &context, request, &response);
   if (!status.ok()) {
     std::cerr << "CreateMetricDescriptor request failed: "
               << opencensus::common::ToString(status) << "\n";
@@ -173,9 +181,25 @@ bool Handler::MaybeRegisterView(
 }  // namespace
 
 // static
-void StackdriverExporter::Register(const StackdriverOptions& opts) {
+void StackdriverExporter::Register(StackdriverOptions&& opts) {
+  opencensus::stats::StatsExporter::RegisterPushHandler(
+      absl::WrapUnique(new Handler(std::move(opts))));
+}
+
+// static, DEPRECATED
+void StackdriverExporter::Register(StackdriverOptions& opts) {
+  // Copy opts but take ownership of metric_service_stub.
+  StackdriverOptions copied_opts;
+  copied_opts.project_id = opts.project_id;
+  copied_opts.opencensus_task = opts.opencensus_task;
+  copied_opts.rpc_deadline = opts.rpc_deadline;
+  copied_opts.monitored_resource = opts.monitored_resource;
+  copied_opts.per_metric_monitored_resource =
+      opts.per_metric_monitored_resource;
+  copied_opts.metric_name_prefix = opts.metric_name_prefix;
+  copied_opts.metric_service_stub = std::move(opts.metric_service_stub);
   opencensus::stats::StatsExporter::RegisterPushHandler(
-      absl::WrapUnique(new Handler(opts)));
+      absl::WrapUnique(new Handler(std::move(opts))));
 }
 
 // static, DEPRECATED
@@ -184,7 +208,7 @@ void StackdriverExporter::Register(absl::string_view project_id,
   StackdriverOptions opts;
   opts.project_id = std::string(project_id);
   opts.opencensus_task = std::string(opencensus_task);
-  Register(opts);
+  Register(std::move(opts));
 }
 
 }  // namespace stats

opencensus/exporters/stats/stackdriver/stackdriver_exporter.h

@@ -15,12 +15,14 @@
 #ifndef OPENCENSUS_EXPORTERS_STATS_STACKDRIVER_STACKDRIVER_EXPORTER_H_
 #define OPENCENSUS_EXPORTERS_STATS_STACKDRIVER_STACKDRIVER_EXPORTER_H_
 
+#include <memory>
 #include <string>
 
 #include "absl/base/macros.h"
 #include "absl/strings/string_view.h"
 #include "absl/time/time.h"
 #include "google/api/monitored_resource.pb.h"
+#include "google/monitoring/v3/metric_service.grpc.pb.h"
 
 namespace opencensus {
 namespace exporters {
@@ -71,14 +73,27 @@ struct StackdriverOptions {
   // If empty, the exporter will use "custom.googleapis.com/opencensus/" by
   // default.
   std::string metric_name_prefix;
+
+  // Optional: by default, the exporter connects to Stackdriver using gRPC. If
+  // this stub is non-null, the exporter will use this stub to send gRPC calls
+  // instead. Useful for testing.
+  std::unique_ptr<google::monitoring::v3::MetricService::Stub>
+      metric_service_stub;
 };
 
 // Exports stats for registered views (see opencensus/stats/stats_exporter.h) to
 // Stackdriver. StackdriverExporter is thread-safe.
 class StackdriverExporter {
  public:
   // Registers the exporter.
-  static void Register(const StackdriverOptions& opts);
+  static void Register(StackdriverOptions&& opts);
+
+  // Registers the exporter. Takes ownership of opts.metric_service_stub
+  // and resets it to nullptr.
+  ABSL_DEPRECATED(
+      "Register() without rvalue StackdriverOptions is deprecated and "
+      "will be removed on or after 2020-01-18")
+  static void Register(StackdriverOptions& opts);
 
   // TODO: Retire this:
   ABSL_DEPRECATED(