CXXCBC-756: Move metric instrumentation points to Public API

CMakeLists.txt

@@ -213,6 +213,7 @@ set(couchbase_cxx_client_FILES
     core/impl/view_error_category.cxx
     core/impl/wildcard_query.cxx
     core/impl/crypto.cxx
+    core/impl/observability_recorder.cxx
     core/io/config_tracker.cxx
     core/io/dns_client.cxx
     core/io/dns_config.cxx

core/bucket.cxx

@@ -120,11 +120,13 @@ class bucket_impl
                         std::optional<key_value_error_map_info> error_info)
   {
     // TODO(SA): copy from mcbp_command, subject to refactor later
+#ifdef COUCHBASE_CXX_CLIENT_CREATE_OPERATION_SPAN_IN_CORE
     metrics::metric_attributes attrs{
       service_type::key_value, fmt::format("{}", req->command_), ec, name_, req->scope_name_,
       req->collection_name_,
     };
     meter_->record_value(std::move(attrs), req->dispatched_time_);
+#endif
 
     if (ec == asio::error::operation_aborted) {
       // TODO(SA): fix tracing

core/cluster.cxx

@@ -1266,6 +1266,11 @@ class cluster_impl : public std::enable_shared_from_this<cluster_impl>
     return tracer_;
   }
 
+  auto meter() const -> const std::shared_ptr<metrics::meter_wrapper>&
+  {
+    return meter_;
+  }
+
 private:
   void setup_observability()
   {
@@ -2474,4 +2479,10 @@ cluster::tracer() const -> const std::shared_ptr<tracing::tracer_wrapper>&
   return impl_->tracer();
 }
 
+auto
+cluster::meter() const -> const std::shared_ptr<metrics::meter_wrapper>&
+{
+  return impl_->meter();
+}
+
 } // namespace couchbase::core

core/cluster.hxx

@@ -44,6 +44,11 @@ namespace tracing
 class tracer_wrapper;
 } // namespace tracing
 
+namespace metrics
+{
+class meter_wrapper;
+} // namespace metrics
+
 namespace mcbp
 {
 class queue_request;
@@ -331,6 +336,7 @@ public:
   [[nodiscard]] auto to_string() const -> std::string;
 
   [[nodiscard]] auto tracer() const -> const std::shared_ptr<tracing::tracer_wrapper>&;
+  [[nodiscard]] auto meter() const -> const std::shared_ptr<metrics::meter_wrapper>&;
 
 private:
   std::shared_ptr<cluster_impl> impl_;