proxysql/deps/prometheus-cpp/registry_counters_reset.patch

diff --git core/include/prometheus/counter.h core/include/prometheus/counter.h
index 6ec01dd..6223106 100644
--- core/include/prometheus/counter.h
+++ core/include/prometheus/counter.h
@@ -46,6 +46,12 @@ class PROMETHEUS_CPP_CORE_EXPORT Counter {
   /// Collect is called by the Registry when collecting metrics.
   ClientMetric Collect() const;
 
+  /// \brief Reset this counter metric to a value of 'zero'.
+  ///
+  /// This function shall only be used in case of 'PROXYSQL STOP' operation
+  /// which invalidates all ProxySQL internal counters for a fresh start.
+  void Reset();
+
  private:
   Gauge gauge_{0.0};
 };
diff --git core/include/prometheus/family.h core/include/prometheus/family.h
index aa94683..925445a 100644
--- core/include/prometheus/family.h
+++ core/include/prometheus/family.h
@@ -135,6 +135,12 @@ class PROMETHEUS_CPP_CORE_EXPORT Family : public Collectable {
   /// \return Zero or more samples for each dimensional data.
   std::vector<MetricFamily> Collect() const override;
 
+  /// \brief Reset all the metrics hold within this specific family.
+  ///
+  /// This function shall only be used in case of 'PROXYSQL STOP' operation
+  /// which invalidates all ProxySQL internal counters for a fresh start.
+  void ResetMetrics();
+
  private:
   std::unordered_map<std::size_t, std::unique_ptr<T>> metrics_;
   std::unordered_map<std::size_t, std::map<std::string, std::string>> labels_;
diff --git core/include/prometheus/registry.h core/include/prometheus/registry.h
index c8fdeb2..e8a58c5 100644
--- core/include/prometheus/registry.h
+++ core/include/prometheus/registry.h
@@ -73,6 +73,12 @@ class PROMETHEUS_CPP_CORE_EXPORT Registry : public Collectable {
   /// \return Zero or more metrics and their samples.
   std::vector<MetricFamily> Collect() const override;
 
+  /// \brief Reset all the counters hold within the registry to a value of zero.
+  ///
+  /// This function shall only be used in case of 'PROXYSQL STOP' operation
+  /// which invalidates all ProxySQL internal counters for a fresh start.
+  void ResetCounters();
+
  private:
   template <typename T>
   friend class detail::Builder;
diff --git core/src/counter.cc core/src/counter.cc
index fc5b6f3..82fb8ae 100644
--- core/src/counter.cc
+++ core/src/counter.cc
@@ -8,6 +8,8 @@ void Counter::Increment(const double val) { gauge_.Increment(val); }
 
 double Counter::Value() const { return gauge_.Value(); }
 
+void Counter::Reset() { gauge_.Set(0.0); }
+
 ClientMetric Counter::Collect() const {
   ClientMetric metric;
   metric.counter.value = Value();
diff --git core/src/family.cc core/src/family.cc
index 83631ab..aa25edb 100644
--- core/src/family.cc
+++ core/src/family.cc
@@ -97,6 +97,17 @@ ClientMetric Family<T>::CollectMetric(std::size_t hash, T* metric) const {
   return collected;
 }
 
+
+template <>
+void Family<Counter>::ResetMetrics() {
+  auto reset_metric =
+      [](std::pair<const std::size_t, std::unique_ptr<Counter>>& metric) {
+          metric.second->Reset();
+      };
+
+  std::for_each(metrics_.begin(), metrics_.end(), reset_metric);
+}
+
 template class PROMETHEUS_CPP_CORE_EXPORT Family<Counter>;
 template class PROMETHEUS_CPP_CORE_EXPORT Family<Gauge>;
 template class PROMETHEUS_CPP_CORE_EXPORT Family<Histogram>;
diff --git core/src/registry.cc core/src/registry.cc
index 1a30a23..d3a660d 100644
--- core/src/registry.cc
+++ core/src/registry.cc
@@ -50,6 +50,12 @@ std::vector<MetricFamily> Registry::Collect() const {
   return results;
 }
 
+void Registry::ResetCounters(){
+	for (auto& family : this->counters_) {
+		family->ResetMetrics();
+	}
+}
+
 template <>
 std::vector<std::unique_ptr<Family<Counter>>>& Registry::GetFamilies() {
   return counters_;