[SDK] Fix MetricProducer interface (#3413)

Author: yashykt

sdk/include/opentelemetry/sdk/metrics/export/metric_producer.h

@@ -82,15 +82,11 @@ struct ResourceMetrics
 class MetricProducer
 {
 public:
-  MetricProducer(std::unique_ptr<MetricFilter> metric_filter = nullptr)
-      : metric_filter_(std::move(metric_filter))
-  {}
+  MetricProducer()          = default;
   virtual ~MetricProducer() = default;
 
   MetricProducer(const MetricProducer &)  = delete;
   MetricProducer(const MetricProducer &&) = delete;
-  void operator=(const MetricProducer &)  = delete;
-  void operator=(const MetricProducer &&) = delete;
 
   enum class Status
   {
@@ -111,8 +107,6 @@ class MetricProducer
    * partial failure.
    */
   virtual Result Produce() noexcept = 0;
-
-  std::unique_ptr<MetricFilter> metric_filter_;
 };
 
 }  // namespace metrics

sdk/src/metrics/state/metric_collector.cc

@@ -76,7 +76,7 @@ MetricProducer::Result MetricCollector::Produce() noexcept
     ScopeMetrics scope_metrics;
     scope_metrics.metric_data_ = std::move(metric_data);
     scope_metrics.scope_       = meter->GetInstrumentationScope();
-    if (!this->metric_filter_)
+    if (!metric_filter_)
     {
       resource_metrics.scope_metric_data_.emplace_back(std::move(scope_metrics));
       return true;
@@ -93,7 +93,7 @@ MetricProducer::Result MetricCollector::Produce() noexcept
       opentelemetry::nostd::string_view unit = metric.instrument_descriptor.unit_;
 
       MetricFilter::MetricFilterResult metric_filter_result =
-          this->metric_filter_->TestMetric(scope, name, type, unit);
+          metric_filter_->TestMetric(scope, name, type, unit);
       if (metric_filter_result == MetricFilter::MetricFilterResult::kAccept)
       {
         filtered_scope_metrics.metric_data_.emplace_back(std::move(metric));
@@ -109,7 +109,7 @@ MetricProducer::Result MetricCollector::Produce() noexcept
       {
         const PointAttributes &attributes = point_data_attr.attributes;
         MetricFilter::AttributesFilterResult attributes_filter_result =
-            this->metric_filter_->TestAttributes(scope, name, type, unit, attributes);
+            metric_filter_->TestAttributes(scope, name, type, unit, attributes);
         if (attributes_filter_result == MetricFilter::AttributesFilterResult::kAccept)
         {
           filtered_point_data_attrs.emplace_back(std::move(point_data_attr));