Allow metrics to be registered twice

Author: poodlewars

cpp/arcticdb/entity/metrics.cpp

@@ -30,8 +30,8 @@ namespace arcticdb {
         arcticdb::log::version().debug("PrometheusInstance created");
     }
 
-    void PrometheusInstance::configure(const MetricsConfig& config, const bool reconfigure) {
-        if (configured_ && !reconfigure) {
+    void PrometheusInstance::configure(const MetricsConfig& config) {
+        if (configured_) {
             arcticdb::log::version().warn("Prometheus already configured; Existing setting will be used");
             if (config.host != cfg_.host) {
                 arcticdb::log::version().warn("New Prometheus host is different from the existing: {} vs {}", config.host, cfg_.host);
@@ -108,35 +108,34 @@ namespace arcticdb {
         }
 
         std::scoped_lock lock{metrics_mutex_};
-        bool inserted{false};
         if (type == prometheus::MetricType::Counter) {
-            inserted = map_counter_.insert({name, &prometheus::BuildCounter()
+            map_counter_[name] = &prometheus::BuildCounter()
                     .Name(name)
                     .Help(help)
                     .Labels(labels)
-                    .Register(*registry_)}).second;
+                    .Register(*registry_);
         } else if (type == prometheus::MetricType::Gauge) {
-            inserted = map_gauge_.insert({name, &prometheus::BuildGauge()
+            map_gauge_[name] = &prometheus::BuildGauge()
                     .Name(name)
                     .Help(help)
                     .Labels(labels)
-                    .Register(*registry_)}).second;
+                    .Register(*registry_);
         } else if (type == prometheus::MetricType::Histogram) {
-            inserted = map_histogram_.insert({name, HistogramInfo{&prometheus::BuildHistogram()
-                    .Name(name)
-                    .Help(help)
-                    .Labels(labels)
-                    .Register(*registry_), buckets_list}}).second;
+            prometheus::Family<prometheus::Histogram>* histogram = &prometheus::BuildHistogram()
+                .Name(name)
+                .Help(help)
+                .Labels(labels)
+                .Register(*registry_);
+            map_histogram_[name] = HistogramInfo(histogram, buckets_list);
         } else if (type == prometheus::MetricType::Summary) {
-            inserted = map_summary_.insert({name, &prometheus::BuildSummary()
+            map_summary_[name] = &prometheus::BuildSummary()
                     .Name(name)
                     .Help(help)
                     .Labels(labels)
-                    .Register(*registry_)}).second;
+                    .Register(*registry_);
         } else {
             util::raise_rte("Unsupported metric type");
         }
-        util::check(inserted, "Expected to register metric {} but was already present", name);
 }
 
 void PrometheusInstance::incrementCounter(const std::string& name, double value, const Labels& labels) {

cpp/arcticdb/entity/metrics.hpp

@@ -150,7 +150,7 @@ class PrometheusInstance {
 
     int push();
 
-    void configure(const MetricsConfig& config, const bool reconfigure = false);
+    void configure(const MetricsConfig& config);
 
     // Intended for testing.
     std::vector<prometheus::MetricFamily> get_metrics();
@@ -160,13 +160,15 @@ class PrometheusInstance {
     private:
 
         struct HistogramInfo {
+            HistogramInfo() = default;
+
             HistogramInfo(prometheus::Family<prometheus::Histogram>* histogram,
                           prometheus::Histogram::BucketBoundaries buckets_list) : histogram_(histogram),
                           buckets_list_(std::move(buckets_list)) {
 
             }
 
-            prometheus::Family<prometheus::Histogram>* histogram_;
+            prometheus::Family<prometheus::Histogram>* histogram_ = nullptr;
             prometheus::Histogram::BucketBoundaries buckets_list_;
         };
 

cpp/arcticdb/entity/test/test_metrics.cpp

@@ -44,7 +44,7 @@ TEST(Metrics, RegisterTwice) {
     PrometheusInstance instance{};
     instance.configure(MetricsConfig{"host", "port", "job", "instance", "local", MetricsConfig::Model::PUSH});
     instance.registerMetric(prometheus::MetricType::Counter, "name", "help");
-    ASSERT_THROW(instance.registerMetric(prometheus::MetricType::Counter, "name", "help"), ArcticException);
+    instance.registerMetric(prometheus::MetricType::Counter, "name", "help");
 }
 
 TEST(Metrics, IncrementCounterSpecific) {